RU2825310C1 - Plant for producing propylene oxide and method of producing propylene oxide - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: present invention relates to an apparatus for producing propylene oxide by epoxidation of propylene using peroxide in the presence of titanosilicate, as well as to versions of the method of producing propylene oxide. Proposed plant comprises at least three reactors configured to store titanosilicate and feed propylene and peroxide as raw material, a feed line configured to feed a reaction material which is not yet supplied to each reactor, to each reactor, and a discharge line which is connected to each reactor and is configured to discharge the reaction mixture containing propylene oxide from each reactor. Plant also includes a switching mechanism configured to switch the state of each reactor between an operating state in which a feedstock for the reaction is fed and an epoxidation reaction is carried out, and an idle state, wherein feed of raw material for reaction is switched off, made with possibility to change reactor in idle state in turn, and also made with possibility to perform switching so that only reactors in working state are connected hydraulically, in series or in parallel, with provision of feed of raw material for reaction into reactors in working condition. Besides, the apparatus includes a sampling mechanism configured to take a portion of the reaction mixture from each discharge line connected to each reactor. Each reactor comprises a feed zone into which a reaction material is supplied, and a discharge zone from which the reaction mixture is discharged, and further comprises thermometers which measure the internal temperature of the supply zone and the discharge zone, respectively.

EFFECT: creation of installation and method of producing propylene oxide, by means of which it is possible to determine easily the catalyst replacement time for each reactor.

20 cl, 32 dwg, 2 tbl, 3 ex

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Japanese Patent Application No. 2020-057674, the disclosure of which is incorporated herein by reference in its entirety.

AREA OF TECHNOLOGY

The present invention relates to a plant for producing propylene oxide and a method for producing propylene oxide.

LEVEL OF TECHNOLOGY

A method for producing propylene oxide is known to be the epoxidation of propylene using peroxide in the presence of a catalyst (see patent literature 1 and 2).

As an apparatus for producing propylene oxide in such a manner, an apparatus including: a plurality of reactors in which a catalyst is stored; a feed line that feeds propylene and peroxide as raw materials for a reaction into each reactor; a discharge line that discharges a reaction mixture containing propylene oxide from each reactor; and connecting lines that connect the reactors to each other to allow the reaction mixture, which is discharged from each reactor and which contains the reaction raw materials, to be supplied to a plurality of other reactors, are known (see Patent Literature 3).

In the production of propylene oxide using such production equipment, one or more reactors of a plurality of reactors are put into an inoperative state in which the feedstock for the reaction is shut off, and a plurality of other reactors are put into an operational state in which the feedstock for the reaction is supplied and the epoxidation reaction is carried out. Thus, the formation of propylene oxide is carried out in a plurality of reactors in an operational state.

When the formation of propylene oxide continues in this manner, the activity of the catalyst decreases, so that the epoxidation reaction cannot be carried out efficiently. Therefore, the catalyst whose activity has been decreased (deactivated) must be replaced in each reactor. Specifically, from a plurality of reactors in the operating state, the reactor in which the catalyst has been deactivated is switched to the inoperative state, and the reactor in the inoperative state is switched to the operating state. Then, the catalyst in the reactor switched to the inoperative state is replaced, while the formation of propylene oxide is carried out in the plurality of reactors in the operating state. In this way, the catalyst can be replaced without stopping the formation of propylene oxide, and thus efficient operation can be carried out.

However, it is difficult to determine in advance the time until catalyst deactivation for each reactor, and therefore it is difficult to determine the catalyst replacement time for each reactor.

LIST OF CITIONS

Patent literature

Patent Literature 1: JP 2005-97175 A

Patent Literature 2: JP 2005-97185 A

Patent Literature 3: JP 2001-526280 T

ESSENCE OF THE INVENTION

Technical problem

Accordingly, the object of the present invention is to provide a plant for producing propylene oxide and a method for producing propylene oxide, by means of which the catalyst replacement time for each reactor can be easily determined.

Solution to the problem

The propylene oxide producing plant of the present invention is a propylene oxide producing plant which produces propylene oxide by epoxidizing propylene using peroxide in the presence of titanosilicate, wherein the plant comprises:

at least three reactors in which titanosilicate is stored and into which propylene and peroxide are fed as reaction feedstock;

a feed line that feeds reaction feedstock that has not yet been fed to each reactor into each reactor;

a discharge line that is connected to each reactor and that discharges the reaction mixture containing propylene oxide from each reactor;

a switching mechanism which is capable of switching the state of each reactor between an operating state, when the feedstock for the reaction is supplied and the epoxidation reaction is carried out, and an inoperative state, when the feedstock for the reaction is turned off, i.e., capable of changing the reactor in the inoperative state in turn, and which performs the switching in such a way that only the reactors in the operating state are hydraulically connected in series or parallel, which allows the feedstock for the reaction to be supplied to the reactors in the operating state; and

a sampling mechanism that takes a portion of the reaction mixture from each discharge line connected to each reactor.

It can be configured such that the propylene oxide production plant of the present invention further comprises

a connecting line which hydraulically connects the reactors to each other and which feeds the reaction mixture discharged from one of the connected reactors to another reactor, where the reaction mixture contains the feedstock for the reaction, where

The switching mechanism connects only the reactors in working condition in series by a connecting line or lines.

It may be configured such that each reactor includes: a feed zone into which the feedstock for the reaction is fed; and a discharge zone from which the reaction mixture is discharged, and

additionally includes thermometers that measure the internal temperature in the feeding and unloading areas, respectively.

It may be configured such that each reactor comprises a titanosilicate bed formed by accumulating titanosilicate, and

additionally includes a thermometer that measures the internal temperature of the titanosilicate layer.

It may be configured such that each reactor includes: a feed zone into which the feedstock for the reaction is fed; and a discharge zone which discharges the reaction mixture, and

additionally includes pressure gauges that measure the internal pressure in the feed and discharge zones, respectively.

At least three reactors can be of approximately the same size.

It can be configured so that each reactor has a cylindrical shape, and when the inner diameter of the reactor is taken to be D (m) and the height of the reactor is taken to be L (m), L/D is from 0.5 to 20.

Each reactor may include a pressure relief valve capable of relieving internal pressure.

It may be configured such that the sampling mechanism includes a sampling line that branches off from each discharge line connected to each reactor and that receives a portion of the reaction mixture, and

the internal diameter of the sampling line is smaller than the internal diameter of the discharge line to which the sampling line is connected.

It may be configured such that the sampling line includes a sealing portion capable of forming a tightly sealed region for retaining the reaction mixture, and has a sampling opening on the sealing portion.

Titanosilicate can be silylated titanosilicate.

Titanosilicate may be titanosilicate silylated with 1,1,1,3,3,3-hexamethyldisilazane.

Peroxide can be organic peroxide.

The organic peroxide may be at least selected from the group consisting of cumene hydroperoxide, ethylbenzene hydroperoxide and tert-butyl hydroperoxide.

The method for producing propylene oxide according to the present invention uses the above-described apparatus for producing propylene oxide and comprises:

(1) the first stage of replacing titanosilicate in the reactor in an inoperative state, while feeding the feedstock for the reaction into the reactors in an operational state and carrying out epoxidation;

(2) a second step of using a switching mechanism to switch a reactor from an inoperative state in which the titanosilicate has been replaced to an operative state, and to switch one or more reactors of the plurality of reactors in an operative state to an inoperative state, and to supply a reaction feedstock to the reactors in an operative state and to carry out epoxidation; and

(3) the stage of sampling a part of the reaction mixture using a sampling mechanism and checking the deactivation state of the titanosilicate, where

the first stage and the second stage are repeated, and thus the epoxidation is carried out while the reactor, which is to be put out of operation, is changed in turn to replace the titanosilicate.

The method for producing propylene oxide according to the present invention uses the above-described apparatus for producing propylene oxide and comprises:

(1) the first stage of replacing titanosilicate in a reactor in an inoperative state, by connecting only the reactors in the operational state in series with a connecting line or lines and feeding the reaction feedstock to the reactors in the operational state and performing epoxidation;

(2) a second step of using a switching mechanism to switch a reactor from an inoperative state in which the titanosilicate has been replaced to an operative state, and to switch one or more reactors from a plurality of reactors in an operative state to an inoperative state, and to connect in series by a connecting line or lines only the reactors in an operative state, and to supply the reaction feedstock to the reactors in an operative state, and to carry out epoxidation; and

(3) the stage of sampling a part of the reaction mixture using a sampling mechanism and checking the deactivation state of the titanosilicate, where

the first stage and the second stage are repeated, and thus the epoxidation is carried out while the reactor, which is to be put out of operation, is changed in turn to replace the titanosilicate.

The time of switching one or more reactors to the non-operating state in the second stage can be determined from the deactivation status of the titanosilicate.

The method for producing propylene oxide according to the present invention may further include a step of separating alcohol from the reaction mixture.

It can be configured such that the second stage includes a first feeding stage consisting of transferring the reactor from the non-working state in which the titanosilicate exchange has been carried out to the working state, and feeding the feedstock for the reaction, in order, propylene, then peroxide, and

at the first stage of feeding, the ratio of the total volume flow rate (β) of propylene fed before the peroxide is fed into the reactor switched from the non-working state to the working state to the volume (α) of titanosilicate stored in the reactor switched from the non-working state to the working state (β/α) is from 5 to 6000.

In the first stage of feeding, the temperature of the titanosilicate layer at the outlet of the reactor can be set from 40 to 150°C, when the peroxide is fed into the reactor, and the reactor is transferred from the non-working state to the working state.

At the first stage of feeding, the temperature of the titanosilicate layer at the reactor outlet can be set from 40 to 150°C when feeding only propylene into the reactor.

BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 is a schematic diagram showing a state of connection of reactors in a propylene oxide producing apparatus according to one embodiment of the present invention.

Fig. 2A is a schematic diagram showing a state of connection of reactors in an operating state in a propylene oxide production plant according to the same embodiment.

Fig. 2B is a schematic diagram showing a state after switching the state of the reactor connection in the operating state from the state in Fig. 2A.

Fig. 3A is a schematic diagram showing a state after switching the state of the reactor connection in the operating state from the state in Fig. 2B in the propylene oxide production apparatus of the same embodiment.

Fig. 3B is a schematic diagram showing a state after switching the state of the reactor connection in the operating state from the state in Fig. 3A.

Fig. 4 is a schematic diagram showing a state after switching the state of the reactor connection in the operating state from the state in Fig. 3B in the propylene oxide production apparatus of the same embodiment.

Fig. 5A is a schematic diagram showing a state of connection of reactors in an operating state in a propylene oxide production plant according to the same embodiment.

Fig. 5B is a schematic diagram showing a state after switching the state of the reactor connection in the operating state from the state in Fig. 5A.

Fig. 6A is a schematic diagram showing a state after switching the state of the reactor connection in the operating state from the state in Fig. 5B in the propylene oxide production apparatus of the same embodiment.

Fig. 6B is a schematic diagram showing a state after switching the state of the reactor connection in the operating state from the state in Fig. 6A.

Fig. 7A is a schematic diagram showing a state after switching the state of the reactor connection in the operating state from the state in Fig. 6B in the propylene oxide production apparatus of the same embodiment.

Fig. 7B is a schematic diagram showing a state after switching the state of the reactor connection in the operating state from the state in Fig. 7A.

Fig. 8 is a schematic diagram showing a state after switching the state of the reactor connection in the operating state from the state in Fig. 7B in the propylene oxide production plant of the same embodiment.

Fig. 9A is a schematic diagram showing a state of connection of reactors in an operating state in a propylene oxide production plant according to the same embodiment.

Fig. 9B is a schematic diagram showing a state after switching the state of the reactor connection in the operating state from the state in Fig. 9A.

Fig. 10A is a schematic diagram showing a state after switching the state of the reactor connection in the operating state from the state in Fig. 9B in the propylene oxide production apparatus of the same embodiment.

Fig. 10B is a schematic diagram showing a state after switching the reactor connection state to the working state from the state in Fig. 10A.

Fig. 11 is a schematic diagram showing a state after switching the state of the reactor connection in the operating state from the state in Fig. 10B in the propylene oxide production apparatus of the same embodiment.

Fig. 12A is a schematic diagram showing a state of connection of reactors in an operating state in a propylene oxide production plant according to another embodiment.

Fig. 12B is a schematic diagram showing a state of connection of reactors in an operating state in a propylene oxide production plant of another embodiment.

Fig. 13A is a schematic diagram showing a state of connection of reactors in an operating state in a propylene oxide production plant of another embodiment.

Fig. 13B is a schematic diagram showing a state of connection of reactors in an operating state in a propylene oxide production plant of another embodiment.

Fig. 14A is a schematic diagram showing the state of the reactor connection in the working state for Working Example 1 of Test 1 in the Examples.

Fig. 14B is a schematic diagram showing a state after switching the state of the reactor connection in the operating state from the state in Fig. 14A.

Fig. 14C is a schematic diagram showing a state after switching the state of the reactor connection in the operating state from the state in Fig. 14B.

Fig. 15A is a schematic diagram showing a state after switching the state of the reactor connection in the working state from the state in Fig. 14C for Working Example 1 of Test 1 in the Examples.

Fig. 15B is a schematic diagram showing a state after switching the state of the reactor connection in the operating state from the state in Fig. 15A.

Fig. 15C is a schematic diagram showing a state after switching the state of the reactor connection in the operating state from the state in Fig. 15B.

Fig. 16 is a schematic diagram showing a state after switching the state of the reactor connection in the working state from the state in Fig. 15C for the working example 1 of the test 1 in the examples.

Fig. 17A is a schematic diagram showing the state of the reactor connection in the working state for Working Example 2 of Test 1 in the Examples.

Fig. 17B is a schematic diagram showing a state after switching the state of the reactor connection in the operating state from the state in Fig. 17A.

Fig. 17C is a schematic diagram showing a state after switching the state of the reactor connection in the operating state from the state in Fig. 17B.

DETAILED DESCRIPTION OF THE PREFERRED IMPLEMENTATION OPTION

Next, a description will be given of one embodiment of the present invention, but the present invention is not limited to the following embodiment. It should be noted that in the following drawings, the same or corresponding parts are designated by the same reference numerals, and the description is not repeated.

The propylene oxide producing apparatus (hereinafter also referred to simply as “production equipment”) 100 of the present embodiment produces propylene oxide by epoxidizing propylene using peroxide in the presence of titanosilicate, as shown in Fig. 1.

In particular, the production equipment 100 according to the present embodiment includes: four reactors 1 in which titanosilicate is stored as a catalyst and into which propylene and peroxide are fed as reaction raw materials; a feed line 2 that feeds reaction raw materials that have not yet been fed into each reactor 1 into each reactor 1; a discharge line 3 that is connected to each reactor 1 and that discharges a reaction mixture containing propylene oxide from each reactor; and a connecting line 4 that hydraulically connects the reactors 1 to each other and that feeds a reaction mixture discharged from one of the connected reactors 1 to another reactor 1, where the reaction mixture contains reaction raw materials. Furthermore, the production equipment 100 includes: a sampling mechanism 5 that samples a portion of the reaction mixture from each discharge line 3 connected to each reactor 1; and a switching mechanism 6 which is capable of switching the state of each reactor 1 between an operating state when the raw material for the reaction is supplied and the epoxidation reaction is carried out, and a non-operating state when the supply of raw material for the reaction is turned off.

The sizes of the four reactors 1 are not particularly limited, and, for example, the four reactors are preferably approximately the same size. Approximately the same size means that, for example, each reactor 1 has a volume of 0.5-1.5 times, preferably 0.6-1.4 times, the average volume of the four reactors 1.

In addition, the shape of the reactor 1 is not particularly limited, and the reactor 1 preferably has, for example, a cylindrical shape. In this case, when the inner diameter (maximum value of the diameter) of the reactor 1 is taken to be D (m), and the height (height of the inner space) of the reactor 1 is taken to be L (m), L/D is preferably from 0.5 to 20, more preferably from 0.4 to 15.

As one aspect, an aspect is given in which the volume of each reactor 1 is from 0.6 to 1.4 of the average volume of four reactors 1, and L/D is from 0.5 to 20. As one aspect, an aspect is given in which the volume of each reactor 1 is from 0.6 to 1.4 of the average volume of four reactors 1, and L/D is from 0.4 to 15.

In addition, each reactor 1 includes: a feed zone 1a, into which a raw material for the reaction is fed; a discharge zone 1b, from which the reaction mixture is discharged; and a titanosilicate layer 1c, formed using the stored titanosilicate. In addition, each reactor 1 includes a pressure relief valve (not shown), capable of releasing the internal pressure.

The feed zone 1a is hydraulically connected to the feed line 2 and the connecting line 4. Thus, the feed zone 1a is configured in such a way that at least one of the types of reaction feedstock (not yet fed to the reactor 1), which is fed from the feed line 2, and the reaction feedstock (unloaded from the reactor 1), which is fed from the connecting lines 4, can be fed to the reactor 1.

The discharge zone 1b is hydraulically connected to the discharge line 3 and the connecting line 4. Thus, the discharge zone 1b is configured in such a way that the reaction mixture can be discharged into the discharge line 3 and the connecting line 4.

The titanosilicate layer 1c may be a fluidized bed (in the form of a slurry) or a fixed bed, but is preferably a fixed bed in the case of a large-scale industrial operation.

In addition, the production equipment 100 may include thermometers (not shown) that measure the internal temperature of the feed zone 1a and the discharge zone 1b. Alternatively, the production equipment 100 may include a thermometer (not shown) that measures the internal temperature of the titanosilicate layer 1c. Alternatively, the production equipment 100 may include thermometers (not shown) that measure the internal temperature of the feed zone 1a, the discharge zone 1b and the titanosilicate layer 1c, respectively.

When the production equipment 100 includes thermometers that measure the internal temperature of the feeding zone 1a and the unloading zone 1b, each of the feeding zone 1a and the unloading zone 1b includes a temperature measuring zone (not shown) in which the thermometer is installed.

The temperature measuring zones of the feed zone 1a and the discharge zone 1b may include a zone of a protective tube (not shown) extending inside the feed zone 1a and the discharge zone 1b. Then, the temperatures in the feed zone 1a and the discharge zone 1b can be measured through the zones of the protective tube by inserting thermocouples of the thermometers into the zones of the protective tube. Alternatively, the temperature measuring zones of the feed zone 1a and the discharge zone 1b can be configured in such a way that the thermocouples of the thermometers can be inserted directly inside the feed zone 1a and the discharge zone 1b.

When the production equipment 100 includes a thermometer that measures the internal temperature of the titanosilicate layer 1c, the titanosilicate layer 1c includes a temperature measuring zone (not shown) in which the thermometer is installed. The temperature measuring zone of the titanosilicate layer 1c can be provided in the raw material unloading zone for the reaction in the titanosilicate layer 1c, or one or more temperature measuring zones of the titanosilicate layer 1c can be provided between the feeding zone and the raw material unloading zone for the reaction in the titanosilicate layer 1c in addition to the unloading zone. Alternatively, one or more temperature measuring zones of the titanosilicate layer 1c can be provided between the feeding zone and the raw material unloading zone for the reaction in the titanosilicate layer 1c.

The temperature measurement zone of the titanosilicate layer 1c may include a protective tube zone (not shown) located in the titanosilicate layer 1c. Then, the temperature in the titanosilicate layer 1c can be measured through the protective tube zone by inserting thermocouples of the thermometer into the protective tube zone. Alternatively, the temperature measurement zone of the titanosilicate layer 1c can be configured in such a way that the thermocouples of the thermometer can be inserted directly into the titanosilicate layer 1c.

In addition, the production equipment 100 may include pressure gauges (not shown) that measure the internal pressure in the feed zone 1a and the discharge zone 1b. In this case, each of the feed zones 1a and the discharge zones 1b includes a pressure measuring zone in which a pressure gauge is installed.

The amount of titanosilicate stored in each reactor 1 is not particularly limited and is, for example, preferably 10% by mass or more, more preferably 20% by mass or more of the total amount of titanosilicate that is used in the entire epoxidation step that is carried out using three reactors 1.

The titanosilicate is not particularly limited as long as it is a known titanosilicate as an epoxidation catalyst. The titanosilicate refers to a compound in which a part of Si in a porous silicate (SiO2) is replaced by Ti. The compound has a bond represented by -Si-O-Ti. Examples of the compound include compounds obtained by supporting a titanium compound on a silica support, compounds obtained by forming a composite with silica by a co-precipitation method or a sol-gel method, and zeolite compounds including titanium.

More specific examples include: the catalysts described in JP 2004-195379 A, JP 373184 B and JP 3797107 B and the like; the catalysts described in US 2005014960 B, CN 102311363 B and the like; the Ti-supported silicon dioxide described in US 2007260074 B; Ti-MCM-41 described in US 5783167 B and the like; Ti-MCM-48 described in JP H-7-300312 A and the like; Ti-HMS, described in Nature 368 (1994) p321, CN 101348472 B, CN 101307039 B, CN 101279960 B, CN 102872847 B, CN 103030611 B and the like; Ti-SBA-15, described in Chemistry of Material 14, 1657-1664, (2002) and the like; Ts-1, described in Journal of Catalysis 130, 1-8, (1991) and the like; TS-2, described in Applied Catalysis 58, L1-L4, (1991) and the like; Ti-Beta, described in Journal of Catalysis 199, 41-47, (2001) and the like; Ti-ZSM-12, described in Zeolites 15, 236-242, (1995) and the like; TAPS0-5, described in Zeolites 15, 228-235, (1995) and the like; Ti-MOR, described in The Journal of Physical Chemistry B 102, 9297-9303 (1998) and the like; Ti-ITQ-7, described in Chemical Communications 761-762, (2000) and the like; Ti-UTD-1, described in Zeolites 15, 519-525, (1995) and the like; and Ti-MWW and its precursors (e.g., JP 2005-262164 A), described in Chemistry Letters 2000 p774 and the like.

In addition, silylated titanosilicate is preferably used as the titanosilicate. The silylation treatment is carried out by contacting the titanosilicate with a silylating agent to convert the hydroxy group present on the surface of the titanosilicate into a silyl group.

Examples of the silylating agent include organic silanes, organic silylamines, organic silylamides and their derivatives, and organic silazanes and other silylating agents.

Examples of organic silanes include chlorotrimethylsilane, dichlorodimethylsilane, chlorobromodimethylsilane, nitrotrimethylsilane, chlorotriethylsilane, iododimethylbutylsilane, chlorodimethylphenylsilane, chlorodimethylsilane, dimethyl n-propylchlorosilane, dimethylisopropylchlorosilane, tert-butyldimethylchlorosilane, tripropylchlorosilane, dimethyloctylchlorosilane, lan, trihexylchlorosilane, dimethylethylchlorosilane, dimethyloctadecylchlorosilane, n-butyldimethylchlorosilane, bromomethyldimethylchlorosilane, chloromethyldimethylchlorosilane , 3-chloropropyldimethylchlorosilane, dimethoxymethylchlorosilane, methylphenylchlorosilane, methylphenylvinylchlorosilane, benzyldimethylchlorosilane, diphenylchlorosilane, diphenylmethylchlorosilane, diphenylvinylchlorosilane, tribezylchlorosilane, methoxytrimethylsilane, dimethoxydimethylsilane, trimethoxymethylsilane, ethoxytrimethylsilane, diethoxydimethylsilane, triethoxymethylsilane, trimethoxyethylsilane, dimethoxydiethylsilane, methoxytriethylsilane, , diethoxydiethylsilane, triethoxyethylsilane, methoxytriphenylsilane, dimethoxydiphenylsilane, trimethoxyphenylsilane, ethoxytriphenylsilane, diethoxydiphenylsilane, triethoxyphenylsilane, dichlorotetramethyldisiloxane, 3- cyanopropyldimethylchlorosilane, 1,3-dichloro-1,1,3,3-tetramethyldisiloxane and 1,3-dimethoxy-1,1,3,3-tetramethyldisiloxane.

Examples of organic silylamines include N-trimethylsilylimidazole, N-tert-butyldimethylsilylimidazole, N-dimethylethylsilylimidazole, N-dimethyl-n-propylsilylimidazole, N-dimethylisopropylsilylimidazole, N-trimethylsilyldimethylamine, N-trimethylsilyldiethylamine, N-trimethylsilylpyrrole, N-trimethylsilylpyrrolidine, N-trimethylsilylpiperidine, 1-cyanoethyl(diethylamino)dimethylsilane, and pentafluorophenyldimethylsilylamine.

Examples of organic silylamides and their derivatives include N,O-bis(trimethylsilyl)acetamide, N,O-bis(trimethylsilyl)trifluoroacetamide, N-(trimethylsilyl)acetamide, N-methyl-N-(trimethylsilyl)acetamide, N-methyl-N-(trimethylsilyl)trifluoroacetamide, N-methyl-N-(trimethylsilyl)heptafluorobutyramide, N-(tert-butyldimethylsilyl)-N-trifluoroacetamide, and N,O-bis(diethylhydrosilyl)trifluoroacetamide.

Examples of organic silazanes include 1,1,1,3,3,3-hexamethyldisilazane, heptamethyldisilazane, 1,1,3,3-tetramethyldisilazane, 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisilazane, 1,3-divinyl-1,1,3,3-tetramethyldisilazane, and 1,3-diphenyl-1,1,3,3-tetramethyldisilazane.

Examples of other silylating agents include N-methoxy-N,O-bis(trimethylsilyl)trifluoroacetamide, N-methoxy-N,O-bis(trimethylsilyl)carbamate, N,O-bis(trimethylsilyl)sulfamate, trimethylsilyl trifluoromethanesulfonate, and N,N'-bis(trimethylsilyl)urea.

A preferred silylating agent is an organic silazane, more preferably 1,1,1,3,3,3-hexamethyldisilazane.

The feed line 2 is hydraulically connected to the feed zone 1a of each reactor 1. In addition, the feed line 2 is configured in such a way that propylene and peroxide, which are the raw materials for the reaction, can be fed in a mixed state or separately from each other into the reactor 1.

In addition, the feed line 2 includes a temperature control means (not shown) that controls the temperature of the reaction feedstock. The temperature control means is not particularly limited, and, for example, a heat exchanger, a heater, a cooler or the like can be used.

The discharge line 3 is connected hydraulically to the discharge zone 1b of each reactor 1. In addition, the discharge line 3 is formed in such a way that it branches off from the connecting line 4. In addition, the discharge line 3 is configured in such a way that the reaction mixture discharged from each reactor 1 does not enter other reactors 1. In other words, the discharge line 3 discharges the reaction mixture outside the region where the epoxidation of propylene is carried out in the reactor 1 (in particular, for example, into a distillation unit that separates the formed alcohol from the reaction mixture).

The connecting line 4 is hydraulically connected to the discharge zone 1b of one of the reactors 1, connected by the connecting line 4, and the feed zone 1a of the other reactor 1. In the present embodiment, each reactor 1 is connected to all the other reactors 1 by the connecting lines 4. Thus, the production equipment is configured in such a way that the reaction mixture (in particular, the reaction raw material contained in the reaction mixture), which is discharged from each reactor 1, can be supplied to all the other reactors. 1. In addition, the connecting line 4 is formed in such a way that it branches from the discharge line 3. In addition, the connecting line 4 includes a temperature control means (not shown) that controls the temperature of the reaction mixture flowing in the connecting line 4. The temperature control means are not particularly limited, and, for example, a heat exchanger, a heater, a cooler or the like can be used.

The sampling mechanism 5 includes: a sampling line 5a, which branches off from each discharge line 3 connected to each reactor 1 and which receives a portion of the reaction mixture; and a sampling valve 5b, which allows the reaction mixture to be taken into the sampling line 5a. The inner diameter of each sampling line 5a is preferably smaller than the inner diameter of the discharge line 3 to which the sampling line 5a is connected. In addition, the sampling line 5a includes a sealing zone 5c capable of being sealed to retain the reaction mixture, and a sampling port (not shown) formed by the sealing zone 5c. In particular, the sampling line 5a includes shut-off valves 5d on the inlet side and the outlet side in the direction of the flow of the reaction mixture in such a way that the sealing zone 5c is located between the shut-off valves 5d, and when the two shut-off valves 5d are closed, thereby forming a tightly closed area.

The switching mechanism 6 is capable of switching the reactor 1 in the non-working state in turn and performs the switching in such a way that only the reactors 1 in the working state are connected hydraulically, in series or in parallel, thereby ensuring the supply of raw material for the reaction to the reactors 1 in the working state. In particular, the switching mechanism 6 consists of a plurality of switching valves 6a, which open and close the feeding lines 2, the discharge lines 3 and the connecting lines 4. When each switching valve 6a is opened or closed, the reactor 1 in the non-working state can be changed, one after another, and the switching can be performed in such a way that only the reactors 1 in the working state are connected hydraulically, in series or in parallel, and the raw material for the reaction can be supplied to the reactors 1 in the working state.

Next, a description will be given of the epoxidation step of propylene using the production equipment 100, which is configured as described above.

As shown in Fig. 2A, when performing the epoxidation step in the present embodiment, the switching mechanism 6 is used such that one reactor 1 (hereinafter also referred to as the "fourth reactor 1D") is in an inoperative state, and the remaining three reactors 1 (hereinafter also referred to as the "first reactor 1A, the second reactor 1B and the third reactor 1C") are in an operative state, and only the reactors 1 in an operative state (the first reactor 1A, the second reactor 1B and the third reactor 1C) are connected in series by connecting lines 4. Then, the reaction feedstock is supplied to the sequentially connected reactors 1 in an operative state, and the epoxidation step is performed.

Specifically, the feedstock for the reaction is supplied from the feed line 2 to the first reactor 1A, which is located ahead of the first to third reactors 1A-1C connected in series. Thus, propylene is epoxidized in the first reactor 1A and propylene oxide is formed, and the reaction mixture containing propylene oxide is discharged into the connecting line 4 from the first reactor 1A. When the epoxidation reaction is carried out again in the first reactor 1A, the feedstock for the reaction to the first reactor 1A is preferably carried out in the following order: propylene, then peroxide, and then the propylene and peroxide are mixed.

The reaction mixture discharged from the first reactor 1A is fed to the second reactor 1B connected to the first reactor 1A by a connecting line 4. The reaction mixture discharged from the first reactor 1A contains propylene and peroxide, which are raw materials for the reaction. Therefore, when the reaction mixture discharged from the first reactor 1A is fed to the second reactor 1B, propylene in the reaction mixture is epoxidized in the second reactor 1B and propylene oxide is formed.

The reaction mixture discharged from the second reactor 1B is then fed to another reactor 1C (hereinafter also referred to as the "third reactor 1C") connected to the second reactor 1B by a connecting line 4. Thus, propylene in the reaction mixture discharged from the second reactor 1B is epoxidized in the third reactor 1C and propylene oxide is formed. Then, the reaction mixture containing propylene oxide is discharged into the discharge line 3 from the third reactor 1C.

As described above, in the present embodiment, the reaction feedstock supplied from the feed line 2 passes through a plurality of reactors 1 (specifically, passes through the first reactors 1A to the third reactors 1C in sequence), and thus an epoxidation step is carried out.

It should be noted that, after the epoxidation step, a step of separating and recovering unreacted propylene from the reaction mixture in the discharge line 3 may be further carried out to recycle the unreacted propylene as a reaction feedstock for the epoxidation step. Distillation can be used as a method for separating and recovering unreacted propylene. In distillation, conditions are usually used under which propylene easily evaporates. The distillation conditions vary depending on the temperature and composition of the reaction solution (reaction mixture) supplied to the distillation column. For example, generally, the pressure in the distillation column is preferably 0 to 5 MPa, more preferably 0 to 3 MPa in terms of relative pressure. In addition, the temperature at the top of the column is preferably -50 to 150°C, more preferably -30 to 140°C. The temperature at the bottom of the column is preferably from 50 to 200°C, more preferably from 80 to 200°C. In addition, a stepwise distillation method of propylene using a plurality of distillation columns can be used.

The unreacted propylene separated and recovered in this way can be mixed with the propylene, which must be fresh and fed to the epoxidation reactor.

The epoxidation reaction temperature in each reactor 1 is, for example, preferably 0 to 200°C; the temperature is preferably 25 to 200°C from the viewpoint of the reaction rate and the economical use of the catalyst; and the temperature is preferably 40 to 150°C from the viewpoint of the reaction selectivity. The temperature is a temperature that is measured in the reaction raw material discharge zone in the titanosilicate layer 1c in the reactor 1 (hereinafter also referred to as the "titanosilicate layer outlet temperature"). When the epoxidation reaction temperature is in the above-described ranges, a favorable reaction rate is achieved, and therefore the amount of catalyst required to obtain the desired reaction amount can be reduced. In addition, when the epoxidation reaction temperature is in the above-described ranges, a decrease in the reaction selectivity can be suppressed. In this way, the amount of the compound formed having a carbon number of 4 in particular is reduced, and consequently the loss of active ingredients during the removal of this substance and the energy required to remove this substance can be reduced.

The pressure in each reactor 1 during the epoxidation reaction is preferably adjusted so that the reaction mixture can remain in a liquid state. The pressure in each reactor 1 is not particularly limited and is, for example, preferably 100 to 10,000 kPa. It should be noted that the pressure in each reactor 1 is calculated as the difference between the internal pressure in the feed zone 1a of each reactor 1 and the internal pressure in the discharge zone 1b of each reactor 1.

The temperature of the reaction mixture in the discharge zone 1b of the first reactor 1A is not particularly limited and is, for example, preferably 90°C or higher, more preferably 100°C or higher. The temperature is obtained by measuring the internal temperature of the discharge zone 1b of the first reactor 1A using a thermometer.

Due to the release of heat by the epoxidation reaction, the temperature of the reaction mixture in the discharge zone 1b of the first reactor 1A can be adjusted, for example, by adjusting at least one of the temperatures of the reaction feedstock in the feed zone 1a of the first reactor 1A (the reaction feedstock that is fed from the feed line 2 to the reactor 1) and the temperature in the first reactor 1A (in particular, the temperature at the outlet of the titanosilicate bed). The temperature of the reaction mixture in the feed zone 1a of the first reactor 1A is the temperature that is measured in the temperature measuring zone included in the feed zone 1a of the first reactor 1A, and the temperature at the outlet of the titanosilicate bed in the first reactor 1A is the temperature that is measured in the temperature measuring zone 1c of the titanosilicate bed.

The temperature of the reaction mixture in the discharge zone 1b of the third reactor 1C is preferably lower than 140°C, more preferably 139°C or lower, still more preferably 138°C or lower. Here, there is a possibility that the reaction mixture contains methyl formate formed together with propylene oxide as an impurity, but by setting the temperature of the reaction mixture in the discharge zone 1b of the third reactor 1C in the above-described ranges, the concentration of methyl formate in the reaction mixture can be reduced.

In addition, the temperature of the reaction mixture in the discharge zone 1b of the third reactor 1C is preferably 115°C or higher, more preferably 117°C or higher, still more preferably 120°C or higher, from the viewpoint of increasing the epoxidation reaction rate. The temperature is obtained by measuring the internal temperature of the discharge zone 1b of the third reactor 1C using a thermometer.

The temperature of the reaction mixture in the discharge zone 1b of the third reactor 1C can be adjusted by adjusting at least one of the temperature of the reaction mixture in the feed zone 1a of the third reactor 1C and the temperature in the third reactor 1C (in particular, the temperature of the titanosilicate layer at the outlet of the third reactor 1C). The temperature of the reaction mixture in the feed zone 1a of the third reactor 1C is the temperature that is measured in the temperature measuring zone included in the feed zone 1a of the third reactor 1C, and the temperature at the outlet of the titanosilicate layer in the third reactor 1C is the temperature that is measured in the temperature measuring zone of the titanosilicate layer 1c.

In addition, the difference obtained by subtracting the temperature of the reaction mixture in the feed zone 1a of the third reactor 1C from the temperature of the reaction mixture in the discharge zone 1b of the third reactor 1C is preferably 30°C or lower, more preferably 15°C or lower.

The peroxide which is a raw material for the reaction in the epoxidation step is not particularly limited, and for example, hydrogen peroxide, organic peroxide or the like can be used. The organic peroxide is not particularly limited, and for example, at least one selected from the group consisting of cumene hydroperoxide, ethylbenzene hydroperoxide and tert-butyl hydroperoxide can be used, and in particular, cumene hydroperoxide is preferably used.

When cumene hydroperoxide is used as the peroxide, the molar ratio of propylene to cumene hydroperoxide (propylene/cumene hydroperoxide) is not particularly limited and is, for example, preferably 2/1 to 50/1. When the molar ratio is 2/1 or more, epoxidation can be carried out at a favorable reaction rate, and therefore the epoxidation reaction can be carried out efficiently. When the molar ratio is 50/1 or less, it is possible to reduce the supply of excess propylene to the reactor 1, and therefore it is possible to reduce the energy consumption required in the step of recovering and recycling propylene.

The epoxidation reaction in each reactor 1 can be carried out in a liquid phase using a solvent. Preferably, the solvent is a liquid at the temperature and pressure during the epoxidation reaction and is substantially inactive with respect to the reaction feedstock and the reaction products. For example, a substance present in the peroxide solution fed from the feed line 2 can be used as a solvent. In particular, when the peroxide is ethylbenzene hydroperoxide or cumene hydroperoxide, ethylbenzene or cumene present in the peroxide solution fed from the feed line 2 can be used as a solvent. In addition, examples of other solvents include monocyclic aromatic solvents (in particular, such as benzene, toluene, chlorobenzene and ortho-dichlorobenzene) and alkanes (in particular, such as octane, decane and dodecane).

The content of propylene oxide in the reaction mixture obtained in the epoxidation step in each reactor 1 is preferably from 1 to 31% by weight, more preferably from 1 to 23% by weight.

When using cumene hydroperoxide as the peroxide, the reaction mixture (which is fed to the reactor 1 via the connecting line 4 and discharged from the discharge line 3) contains propylene oxide and cumyl alcohol. The content of cumyl alcohol in the reaction mixture obtained in the epoxidation step in each reactor 1 is preferably from 5 to 80 mass %, more preferably from 5 to 60 mass %, even more preferably from 5 to 40 mass %. In the present document, cumyl alcohol means 2-phenyl-2-propanol.

It should be noted that after the above-described epoxidation step, there follows a step (hereinafter also referred to as "alcohol separation step") of separating alcohol (in particular, cumyl alcohol in the case where cumene hydroperoxide is used as the peroxide) from the reaction mixture (which is discharged from the discharge line 3). By carrying out the alcohol separation step, it is possible to obtain crude propylene oxide in which the alcohol has been separated from the reaction mixture (which is discharged from the discharge line 3). The reaction mixture, which is the object of the alcohol separation step, can be obtained by separating unreacted propylene after the epoxidation step.

Examples of the method for separating alcohol in the alcohol separating step include a method using a distillation column (preferably, multiple distillation columns). In such a method, the pressure in the distillation column is preferably 100 to 5000 kPa, more preferably 100 to 3000 kPa. Further, in such a method, the temperature at the top of the column is preferably -50 to 150°C, more preferably 0 to 130°C. In this case, the temperature at the bottom of the column is preferably 50 to 230°C, more preferably 60 to 210°C.

The content of propylene oxide in the crude propylene oxide obtained by carrying out the alcohol separation step is not particularly limited and is, for example, preferably 99% by mass or more based on 100% by mass of the crude propylene oxide.

An alcohol conversion step may be carried out, which consists of converting the alcohol separated in the alcohol recovery step into another compound. Examples of an alcohol conversion step include:

the stage of alcohol hydrogenolysis in the presence of a catalyst to obtain a hydrocarbon;

a stage of dehydration of the alcohol in the presence of a catalyst and subsequent interaction of the resulting product with hydrogen to obtain a hydrocarbon; and

the stage of interaction of alcohol and peroxide in the presence of a catalyst to obtain dialkyl peroxide.

When the alcohol is cumyl alcohol, the hydrocarbon is cumene. When the alcohol is cumyl alcohol, the dialkyl peroxide is dicumyl peroxide. In other words, when the isolated alcohol is, for example, cumyl alcohol, the alcohol conversion step is the step of converting cumyl alcohol to cumene and/or dicumyl peroxide.

In one aspect, the alcohol conversion step comprises: a step of dehydrating cumyl alcohol in the presence of a catalyst in a cumyl alcohol-containing residual mixture obtained in the alcohol separation step to obtain an α-methylstyrene-containing mixture (hereinafter referred to as a "dehydration step"); and a step of contacting the α-methylstyrene-containing mixture obtained in the dehydration step and hydrogen with each other in the presence of a catalyst to react the α-methylstyrene in the mixture with hydrogen to thereby obtain a conversion mixture containing cumene (hereinafter referred to as a "hydrogenation step").

In another aspect, the alcohol conversion step is a step of contacting the residual mixture containing cumyl alcohol obtained in the alcohol separation step and hydrogen with each other in the presence of a catalyst for reacting the cumyl alcohol in the residual mixture with hydrogen, thereby obtaining a cumene-containing conversion mixture (hereinafter referred to as the "hydrogenolysis step").

Below, a description will be given of a variant where the alcohol conversion stage includes a dehydration stage and a hydrogenation stage.

Examples of the catalyst used in the dehydration step (hereinafter referred to as the "dehydration catalyst") include acids such as sulfuric acid, phosphoric acid and p-toluenesulfonic acid, and metal oxides such as activated alumina, titanium dioxide, zirconia, aluminosilicate and zeolite. From the viewpoint of improving the reaction efficiency, the catalyst is preferably a solid catalyst, more preferably activated alumina.

The dehydration reaction in the dehydration step is usually carried out by contacting cumyl alcohol and a dehydration catalyst with each other. In one embodiment, the hydrogenation reaction in the hydrogenation step is carried out after the dehydration reaction, and therefore the cumyl alcohol and the dehydration catalyst can be contacted with each other in the presence of hydrogen. The dehydration reaction can be carried out in a liquid phase in the presence of a solvent. The solvent must be substantially inactive with respect to the raw material and the reaction products. The solvent can be a substance present in the residual mixture containing cumyl alcohol used. For example, when the residual mixture containing cumyl alcohol contains cumene, this cumene can be used as a solvent and there is no need to use another solvent. Typically, the dehydration reaction temperature is preferably from 50 to 450 °C, more preferably from 150 to 300 °C. Typically, the dehydration reaction pressure is preferably 10 to 10,000 kPaG, more preferably 500 to 4,000 kPaG, still more preferably 1,000 to 2,000 kPaG.

Examples of the catalyst used in the hydrogenation step (hereinafter referred to as the "hydrogenation catalyst") include catalysts containing a metal of Group 10 or Group 11 in the periodic table, and specific examples include nickel-containing catalysts, palladium-containing catalysts, platinum-containing catalysts and copper-containing catalysts. From the viewpoint of suppressing the nuclear hydrogenation reaction of the aromatic ring and a high yield, the catalyst is preferably a nickel-containing catalyst, a palladium-containing catalyst or a copper-containing catalyst. The nickel-containing catalyst is preferably nickel, nickel-alumina, nickel-silica or nickel-carbon, the palladium-containing catalyst is preferably palladium-alumina, palladium-silica or palladium-carbon, and the copper-containing catalyst is preferably copper, Raney copper, copper-chromium, copper-zinc, copper-chromium-zinc, copper-silica or copper-alumina. These catalysts can be used individually or several of these catalysts can be used in combination.

The hydrogenation reaction in the hydrogenation step is carried out by contacting α-methylstyrene and hydrogen with a hydrogenation catalyst. In one embodiment, the hydrogenation reaction is carried out after the dehydration reaction, but in this aspect, a part of the water generated in the dehydration reaction may be separated by oil-water separation and the like, or may be contacted with the hydrogenation catalyst together with α-methylstyrene instead of separation. The amount of hydrogen required for the hydrogenation reaction may be equimolar to the amount of α-methylstyrene, but an excess amount of hydrogen is usually used because the mixture containing α-methylstyrene obtained in the dehydration step contains hydrogen consuming components other than α-methylstyrene. In addition, generally the hydrogen/α-methylstyrene molar ratio is preferably 1/1 to 20/1, more preferably 1/1 to 10/1, still more preferably 1/1 to 3/1, since the reaction proceeds faster as the partial pressure of hydrogen increases. The excess hydrogen remaining after the hydrogenation reaction can be used by recycling after separation from the reaction solution (conversion mixture). The hydrogenation reaction can be carried out in the liquid phase in the presence of a solvent, or in the gas phase. The solvent must be substantially inactive with respect to the feedstock and the reaction products. The solvent may be a substance present in the mixture containing α-methylstyrene. For example, when the mixture containing α-methylstyrene contains cumene, this cumene can be used as a solvent, and there is no need to use another solvent. Usually, the hydrogenation reaction temperature is preferably 0 to 500°C, more preferably 30 to 400°C, still more preferably 50 to 300°C. Usually, the hydrogenation reaction pressure is preferably 100 to 10,000 kPa-g, more preferably 500 to 4,000 kPa-g, still more preferably 1,000 to 2,000 kPa-g.

The dehydration reaction and the hydrogenation reaction can be preferably carried out in the form of a slurry or a fixed bed. In the case of a large-scale industrial operation, it is preferable to use a fixed bed. In addition, the dehydration reaction and the hydrogenation reaction can be carried out in reaction forms such as a batch process, a semi-continuous process or a continuous process. Separate reactors or a single reactor can be used for the dehydration reaction and the hydrogenation reaction. Reactors for a continuous process include an adiabatic reactor and an isothermal reactor, but an adiabatic reactor is preferable because an isothermal reactor needs heat removal equipment.

Examples of the catalyst used in the hydrogenolysis step (hereinafter referred to as the "hydrogenolysis catalyst") include catalysts containing a metal of Group 9, 10, 11 or 12 in the periodic table, and specific examples include cobalt-containing catalysts, nickel-containing catalysts, palladium-containing catalysts, copper-containing catalysts and zinc-containing catalysts. From the viewpoint of suppressing the formation of by-products, the catalyst is preferably a nickel-containing catalyst, a palladium-containing catalyst or a copper-containing catalyst. Examples of the nickel-containing catalyst include nickel, nickel-alumina, nickel-silica and nickel-carbon, examples of the palladium-containing catalyst include palladium-alumina, palladium-silica and palladium-carbon, and examples of the copper-containing catalyst include copper, Raney copper, copper-chromium, copper-zinc, copper-chromium-zinc, copper-silica and copper-alumina. The hydrogenolysis reaction can be carried out in the liquid phase in the presence of a solvent or in the gas phase. The solvent must be substantially inactive with respect to the feedstock and the reaction products. The solvent may be a substance present in the residual mixture containing cumyl alcohol used. For example, when the residual mixture containing cumyl alcohol contains cumene, this cumene can be used as a solvent and there is no need to use another solvent. The amount of hydrogen required for the hydrogenolysis reaction may be equimolar to the amount of cumyl alcohol, but an excess amount of hydrogen is usually used since hydrogen-containing components other than cumyl alcohol are contained in the mixture containing cumyl alcohol obtained in the alcohol separation step. In addition, usually the hydrogen/cumyl alcohol molar ratio is preferably adjusted to 1/1 to 20/1, more preferably 1/1 to 10/1, still more preferably 1/1 to 3/1, since the reaction proceeds more rapidly as the partial pressure of hydrogen increases. Excess hydrogen remaining after the hydrogenolysis reaction can be used by recycling after separation from the reaction solution. Usually, the hydrogenolysis reaction temperature is preferably 0 to 500°C, more preferably 50 to 450°C, still more preferably 150 to 300°C. Usually, the hydrogenolysis reaction pressure is preferably 100 to 10,000 kPaG, more preferably 500 to 4,000 kPaG, still more preferably 1,000 to 2,000 kPaG. The hydrogenolysis reaction can be preferably carried out in the form of a suspension or a fixed bed. In the case of a large-scale industrial operation, it is preferable to use a fixed bed. In addition, the hydrogenolysis reaction can be carried out in a reaction form such as a batch process, a semi-continuous process, or a continuous process.

Typically, the cumene content in the cumene-containing conversion mixture is preferably 90% or more based on 100% by weight of the cumene-containing conversion mixture.

Next, a description will be given of a method for replacing titanosilicate stored in each reactor 1 in the production equipment 100 configured as described above.

When titanosilicate in one reactor 1 of three reactors in the working state has been deactivated, reactor 1 in which titanosilicate has been deactivated is switched to the non-working state, and reactor 1 already in the non-working state is switched to the working state by switching mechanism 6. In addition, by switching mechanism 6, only reactors 1 in the working state (specifically, reactor 1 switched to the working state and reactors 1 in the working state from the very beginning) are connected in series by connecting lines 4, and the reaction feedstock is supplied to the reactors 1 in the working state. In particular, the reaction feedstock is supplied from the feed line 2 to the reactor 1 which is located in front of the reactors connected in series, and the reaction mixture is supplied from the connecting lines 4 to the other reactors 1 connected in series. Thus, the titanosilicate stored in reactor 1 switched to the non-operating state is replaced, while the epoxidation of propylene is carried out in reactors 1 in the operating state (i.e., while the epoxidation step described above is carried out).

By repeating the above step, the reactor 1 to be put into the non-operating state is changed in turn to replace the titanosilicate. In other words, when replacing the titanosilicate stored in each reactor 1 in the production equipment 100, the titanosilicate is exchanged in the reactor 1 to be exchanged, while the epoxidation of propylene is carried out in a plurality of reactors 1 not to be exchanged.

A more specific description of the method for replacing the titanosilicate stored in each reactor 1 will be given below.

<During deactivation of titanosilicate in the third reactor 1C>

As shown in Fig. 2A, the first reactor 1A, the second reactor 1B and the third reactor 1C are connected in series by connecting lines 4, and the epoxidation step is carried out as described above, where the fourth reactor 1D is in an inoperative state, and thus, when the titanosilicate in the third reactor 1C is deactivated, first, a gradual switching is carried out by the above-described switching mechanism 6 so that propylene fed to the first reactor 1A from the feed line 2 is fed to the fourth reactor 1D, and the switching is carried out by the above-described switching mechanism 6 so that propylene discharged from the fourth reactor 1 enters the first reactor 1A through the connecting line 4, as shown in Fig. 2B. Thus, propylene discharged from the fourth reactor 1D is fed to the first reactor 1A.

The time for feeding propylene from the fourth reactor 1D to the first reactor 1A is not particularly limited and may be, for example, from 6 to 720 hours, preferably from 72 hours to 340 hours.

In addition, the temperature of the titanosilicate layer (the temperature at the outlet of the titanosilicate layer) when feeding propylene from the fourth reactor 1D to the first reactor 1A is not particularly limited and is, for example, preferably from 40°C to 150°C, more preferably from 40°C to 90°C.

In addition, when feeding propylene from the fourth reactor 1D to the first reactor 1A, the ratio of the total volume flow rate (β) of propylene fed before feeding the peroxide to the volume (α) of titanosilicate stored in the reactor 1 switched from the non-working state to the working state (β/α) is not particularly limited and is, for example, preferably 5 to 6000, more preferably 600 to 3000.

Next, as shown in Fig. 3A, switching is carried out by the above-described switching mechanism 6 in such a way that part of the peroxide supplied to the first reactor 1A from the feed line 2 is supplied to the fourth reactor 1D. Thus, propylene is epoxidized in the fourth reactor 1D. Then, the reaction mixture discharged from the fourth reactor 1D is supplied to the first reactor 1A via the connecting line 4.

The temperature of the titanosilicate layer (the temperature at the outlet of the titanosilicate layer) after feeding the peroxide into the fourth reactor 1D is not particularly limited and is, for example, preferably 150°C or lower, more preferably 80°C to 140°C.

In addition, by means of the above-described switching mechanism 6, the switching is carried out in such a way that a part of the reaction mixture supplied from the second reactor 1B to the third reactor 1C via the connecting line 4 is discharged from the second reactor 1B to the discharge line 3, the amount of the reaction mixture discharged to the discharge line 3 from the second reactor 1B is gradually increased, and the amount of the reaction mixture discharged from the second reactor 1B to the third reactor 1C is gradually reduced until the supply of the reaction mixture from the second reactor 1B to the third reactor 1C is turned off. Thus, the third reactor 1C is transferred to an inoperative state, as shown in Fig. 3B.

Then, by means of the above-described switching mechanism 6, the amount of peroxide supplied to the fourth reactor 1D from the feed line 2 is gradually increased, and the amount of peroxide supplied to the first reactor 1A from the feed line 2 is gradually decreased to shut off the supply of peroxide to the first reactor 1A from the feed line 2, as shown in Fig. 4.

Thus, the titanosilicate in the third reactor 1C, which is in an inoperative state, is replaced by a non-deactivated one, while the epoxidation of propylene is carried out (i.e., the above-described epoxidation stage is carried out) in the fourth reactor 1D, the first reactor 1A and the second reactor 1B.

<During deactivation of titanosilicate in the first reactor 1A>

As shown in Fig. 5A, the first reactor 1A, the second reactor 1B and the third reactor 1C are connected in series by connecting lines 4, and the epoxidation step is carried out as described above, where the fourth reactor 1D is in an inoperative state, and thus, when the titanosilicate in the first reactor 1A is deactivated, the switching is first performed gradually by the above-described switching mechanism 6 in such a way that propylene fed to the first reactor 1A from the feed line 2 is fed to the fourth reactor 1D, and the switching is carried out by the above-described switching mechanism 6 in such a way that propylene discharged from the fourth reactor 1D enters the first reactor 1A through the connecting line 4, as shown in Fig. 5B. Thus, propylene discharged from the fourth reactor 1D is fed to the first reactor 1A.

The time of feeding propylene from the fourth reactor 1D to the first reactor 1A can be set in the same manner as described in the section <When deactivating titanosilicate in the third reactor 1C>.

In addition, the temperature of the titanosilicate bed (the temperature at the outlet of the titanosilicate bed) when feeding propylene from the fourth reactor 1D to the first reactor 1A can be set in the same manner as described in the section <When deactivating titanosilicate in the third reactor 1C>.

In addition, the ratio of the total volume flow rate (β) of propylene fed before the peroxide is fed to the volume (α) of titanosilicate stored in reactor 1 converted from the inoperative state to the operative state (β/α) can be set in the same manner as described in the section <When deactivating titanosilicate in the third reactor 1C>.

Next, as shown in Fig. 6A, switching is carried out by switching mechanism 6 in such a way that part of the peroxide fed to the first reactor 1A from feed line 2 is fed to the fourth reactor 1D and to the second reactor 1B. Thus, propylene is epoxidized in the fourth reactor 1D. Then, the reaction mixture discharged from the fourth reactor 1D is fed to the first reactor 1A through connecting line 4.

The temperature of the titanosilicate bed (the temperature at the outlet of the titanosilicate bed) after feeding the peroxide into the fourth reactor 1D can be set in the same manner as described in the section <When deactivating titanosilicate in the third reactor 1C>.

Then, by means of the above-described switching mechanism 6, the amount of peroxide supplied to the fourth reactor 1D and the second reactor 1B from the feed lines 2 is gradually increased, and the amount of peroxide supplied to the first reactor 1A from the feed line 2 is gradually decreased to shut off the supply of peroxide to the first reactor 1A from the feed line 2, as shown in Fig. 6B.

Next, as shown in Fig. 7A and Fig. 7B, by means of the above-described switching mechanism 6, switching is performed in such a manner that the reaction mixture discharged from the fourth reactor 1D is supplied to the second reactor 1B through the connecting line 4, the supply of the reaction mixture from the fourth reactor 1D to the second reactor 1B is gradually increased, the supply of the reaction mixture from the first reactor 1A to the second reactor 1B is gradually reduced, and then the supply of the reaction mixture from the fourth reactor 1D to the first reactor 1A is gradually reduced to cut off the supply of the reaction mixture to the first reactor 1A. Thus, the first reactor 1A is put into an inoperative state.

Then, by means of the above-described switching mechanism 6, the amount of peroxide supplied to the fourth reactor 1D from the feed line 2 is gradually increased, and the amount of peroxide supplied to the second reactor 1B from the feed line 2 is gradually decreased to shut off the supply of peroxide to the second reactor 1B from the feed line 2, as shown in Fig. 8.

Thus, the titanosilicate in the first reactor 1A, which is in an inactive state, is replaced by a non-deactivated one, while the epoxidation of propylene is carried out (i.e. the above-described epoxidation stage is carried out) in the fourth reactor 1D, the second reactor 1B and the third reactor 1C.

<During deactivation of titanosilicate in the second reactor 1B>

As shown in Fig. 9A, the first reactor 1A, the second reactor 1B and the third reactor 1C are connected in series by connecting lines 4, and the epoxidation step is carried out as described above, wherein the fourth reactor 1D is in an inoperative state, and thus, when the titanosilicate in the second reactor 1B is deactivated, switching is first carried out gradually by the switching mechanism 6 in such a way that propylene fed to the first reactor 1A from the feed line 2 is fed to the fourth reactor 1D, and switching is carried out by the switching mechanism 6 in such a way that propylene discharged from the fourth reactor 1D is fed to the first reactor 1A through the connecting line 4, as shown in Fig. 9B. Thus, propylene discharged from the fourth reactor 1D is fed to the first reactor 1A. The time of feeding propylene from the fourth reactor 1D to the first reactor 1A can be set in the same manner as described in the section <When deactivating titanosilicate in the third reactor 1C>.

In addition, the temperature of the titanosilicate bed (the temperature at the outlet of the titanosilicate bed) when feeding propylene from the fourth reactor 1D to the first reactor 1A can be set in the same manner as described in the section <When deactivating titanosilicate in the third reactor 1C>.

In addition, the ratio of the total volume flow rate (β) of propylene fed before the peroxide is fed to the volume (α) of titanosilicate stored in reactor 1 converted from the inoperative state to the operative state (β/α) can be set in the same manner as described in the section <When deactivating titanosilicate in the third reactor 1C>.

Next, as shown in Fig. 10A, switching is performed by the above-described switching mechanism 6 in such a way that a part of the peroxide supplied to the first reactor 1A from the feed line 2 is supplied to the fourth reactor 1D, and switching is performed by the above-described switching mechanism 6 in such a way that the reaction mixture discharged from the first reactor 1A is supplied to the third reactor 1C. Thus, propylene is epoxidized in the fourth reactor 1D. Then, the reaction mixture discharged from the fourth reactor 1D is supplied to the first reactor 1A through the connecting line 4, and the reaction mixture discharged from the first reactor 1A is supplied to the third reactor 1C through the connecting line 4.

The temperature of the titanosilicate bed (the temperature at the outlet of the titanosilicate bed) after feeding the peroxide into the fourth reactor 1D can be set in the same manner as described in the section <When deactivating titanosilicate in the third reactor 1C>.

Next, by means of the above-described switching mechanism 6, the feed of the reaction mixture from the first reactor 1A to the third reactor 1C is gradually increased, the feed of the reaction mixture from the first reactor 1A to the second reactor 1B is gradually reduced, and then the feed of the reaction mixture from the second reactor 1B to the third reactor 1C is gradually reduced to shut off the feed of the reaction mixture to the second reactor 1B. Thus, the second reactor 1B is put into an inoperative state, as shown in Fig. 10B.

Then, by means of the above-described switching mechanism 6, the supply of peroxide to the fourth reactor 1D from the supply line 2 is gradually increased, and the supply of peroxide to the first reactor 1A from the supply line 2 is gradually reduced to shut off the supply of peroxide to the first reactor 1A from the supply line 2, as shown in Fig. 11.

Thus, the titanosilicate in the second reactor 1B, which is in an inoperative state, is replaced by non-deactivated titanosilicate, while the epoxidation of propylene is carried out (i.e. the above-described epoxidation step is carried out) in the fourth reactor 1D, the first reactor 1A and the third reactor 1C.

As described above, when replacing titanosilicate in each reactor 1, a part of the reaction mixture in the discharge line 3 is sampled by the sampling mechanism 5 to check the deactivation status of titanosilicate (sampling step), as shown in Fig. 1, and the reactor 1 in the operating state is switched to the non-operating state in accordance with the deactivation status.

The deactivation status of titanosilicate can be determined by the content (hereinafter also referred to as "initial content") of a given component in the reaction mixture discharged from the reactor 1 shortly after being put into operation, and the content (hereinafter also referred to as "post-use content") of a given component in the reaction mixture discharged from the reactor 1 used for a given time after being put into operation. For example, the deactivation status of titanosilicate can be understood by determining the activity k (specifically, the activity k0 based on the initial content and the activity ke based on the post-use content) of titanosilicate, which will be mentioned below.

When determining the initial content and the content after use, the sampling valve 5b of the sampling line 5a is opened to take a part of the reaction mixture into the sampling line 5a from the discharge line 3. Then, in a state where the reaction mixture flows into the sealing zone 5c of the sampling line 5a, the two sealing valves 5d, 5d are closed to form a tightly sealed area. Then, a sample of the reaction mixture is taken from the sampling port of the sealing zone 5c to determine the content (initial content or content after use) of a predetermined component in the sampled reaction mixture. The component whose content is to be determined is not particularly limited as long as it is a component related to the deactivation status of titanosilicate, and examples thereof include peroxide. When determining the peroxide content, a known method can be used, and iodometry or near infrared (NIR) measurement or liquid chromatography (LC) can be used (however, when the measured sample contains propylene, it is necessary to correct the measurement result for the concentration excluding propylene).

The moment of switching the reactor 1 from the working state to the non-working state preferably falls at the time when the activity coefficient ke, calculated from the content (content after use) of peroxide in the reaction mixture discharged from the reactor 1 in the working state, to the activity k0, calculated from the content (initial content) of peroxide in the reaction mixture discharged when switching the reactor 1 to the working state from the non-working state, (ke/k0), becomes from 1/2 to 1/50, more preferably from 1/5 to 1/20. It should be noted that the activity k (the k0 described above and the ke described above) of titanosilicate is determined as follows.

The activation energy Ea (kJ/mol) of titanosilicate is determined by constructing an Arrhenius plot for the titanosilicate used.

The contact time t is calculated using the following equation (1).

t (time) = (volume of titanosilicate) / { (mass of supplied propylene) / ρC3' + (mass of supplied peroxide) / ρOX + (mass of supplied solvent for peroxide) / ρs} ∙∙∙ (1)

The “volume of titanosilicate” in equation (1) is calculated using the following equation (2).

Volume of titanosilicate (L) = (cross-sectional area of reactor 1 at the location of titanosilicate layer 1c) × (height of titanosilicate layer 1c) ∙∙∙(2)

In equation (1) and the following equations (3) and (4), “ρ” means density, and the density of peroxide ρOX (g/ml)=0.985, the density of the solvent diluting the peroxide ρs (g/ml)=0.886, and the density of propylene ρC3' (g/ml)=0.367.

The molar concentration A of peroxide and the molar concentration B of propylene are determined by the following equations (3) and (4).

Molar concentration A of peroxide (mol/L)={(FOX) × (peroxide concentration) × 1000}/{(FOX/ρOX+Fs/ρs+FC3'/ρC3') × (molecular weight of peroxide)} ∙∙∙(3)

Molar concentration B of propylene (mol/l)=(FC3') × 1000/{(FOX/ρOX+Fs/ρs+FC3'/ρC3') × (molecular weight of propylene)} ∙∙∙(4)

In equations (3) and (4), "FOX" represents the mass (kg) of peroxide fed, "Fs" represents the mass (kg) of solvent fed, a solvent that dilutes the peroxide, and "FC3'" represents the mass (kg) of propylene fed.

The conversion X (%) of peroxide is determined by the following equation (5).

Conversion of X peroxide (%) = {(concentration of peroxide at the reactor inlet) - (concentration of peroxide at the reactor outlet)}/(concentration of peroxide at the reactor inlet) × 100 ∙∙∙(5)

In equation (5), the “reactor inlet” represents the feed zone 1a, and the “reactor outlet” represents the discharge zone 1b.

The "peroxide concentration at the reactor inlet" may be obtained by sampling a portion of the reaction mixture from feed zone 1a to determine the peroxide content of the sampled reaction mixture, or may be obtained by determining the peroxide content of the reaction feed that comes from feed line 2.

The "peroxide concentration at the reactor outlet" can be obtained by sampling a portion of the reaction mixture from sampling line 5a to determine the peroxide content in the sampled reaction mixture.

The average temperature Tav by integration using the trapezoid formula is determined by the following equation (6).

Average temperature Tav by integration using the trapezoid formula = {(T1+T2) × L2 + (T2+T3) × L3 + ∙∙∙+ (T(z-1) + Tz) × Lz}/2/(L2+L3+ ∙∙∙+ Lz) ∙∙∙(6)

In equation (6), “T1” represents the temperature of feed zone 1a of reactor 1.

In equation (6), “Tz” represents the temperature of the discharge zone 1b of reactor 1.

In equation (6), “T2, T3, ∙∙∙T(z-1)” represent temperatures that are measured at a plurality of temperature measurement zones located at intervals in the height direction of the titanosilicate layer 1c, and the height of the temperature measurement zone decreases in the specified order.

In equation (6), “L2” is the length between the uppermost part of the titanosilicate layer 1c and the temperature measurement zone where the temperature is T2.

In equation (6), each of “L3 ∙∙∙L(z-1)” represents the length between temperature measurement zones adjacent to each other in the vertical direction in the temperature measurement zones corresponding to “T2, T3, ∙∙∙T(z-1)”, respectively.

In equation (6), “Lz” is the length between the lowest part of the titanosilicate layer 1c and the temperature measurement zone corresponding to T(z-1).

Then, the activity k is determined from the above-described “molar concentration of peroxide A”, “molar concentration of propylene B”, “contact time t”, “conversion of peroxide X”, “activation energy of titanosilicate Ea” and “average temperature Tav by integration using the trapezoidal formula” according to the following equation (7).

Activity k=[1/(BA) × ln{(B-AX/100)/(A-AX/100)}]/t × exp{-Ea × 1000/8.13 × (Tav+273)/( 80+273)} ∙∙∙( 7)

When switching the reactor 1 in the idle state in which titanosilicate has been replaced to the operative state to start feeding the raw material, the raw material for the reaction is preferably fed in the following order: propylene, then peroxide. In this case, the ratio of the total volumetric flow rate (β) of propylene fed to the reactor 1 switched from the idle state to the operative state before feeding the peroxide to the volume (α) of titanosilicate stored in the reactor 1 switched from the idle state to the operative state (β/α) is preferably from 5 to 6000, more preferably from 600 to 3000. The volume of titanosilicate can be determined from (cross-sectional area of the reactor) × (height of the titanosilicate layer 1c). The volumetric flow rate of the fed propylene can be calculated using the mass and density of the fed propylene.

The feed propylene may contain impurities such as propane or butane. The density usually varies with the concentration of impurities, and the above volumetric flow rate of propylene is calculated assuming a density of 0.5027 g/ml.

In addition, as described above, the temperature at the outlet of the titanosilicate layer in the reactor 1 when only propylene is fed into the reactor 1 switched to the operating state is preferably from 40 to 150°C, more preferably from 40 to 90.

In addition, as described above, the temperature of the titanosilicate layer at the outlet of the reactor 1 at the time of feeding the peroxide after feeding the propylene into the reactor 1 switched to the operating state is preferably from 40 to 150°C, more preferably from 80 to 140°C.

The production equipment 100 of the present embodiment, as described above, is a propylene oxide production plant that produces propylene oxide by epoxidizing propylene using peroxide in the presence of titanosilicate, wherein the plant includes: at least three reactors 1 in which titanosilicate is stored and into which propylene and peroxide are fed as reaction feedstock; a feed line that feeds reaction feedstock that has not yet been fed into each reactor into each reactor; a discharge line 3 that is connected to each reactor 1 and that discharges a reaction mixture containing propylene oxide from each reactor 1; a switching mechanism 6 which is capable of switching the state of each reactor 1 between an operating state when a raw material for the reaction is supplied and the epoxidation reaction is carried out, and a non-operating state when the supply of raw material for the reaction is turned off, which is capable of changing the reactor 1 in the non-operating state in turn, and which performs the switching in such a way that only the reactors 1 in the operating state are hydraulically connected in series or in parallel, thereby ensuring the supply of raw material for the reaction to the reactors 1 in the operating state; and a sampling mechanism 5 which samples a part of the reaction mixture from each discharge line 3 connected to each reactor 1.

According to this configuration, the reactors 1 in the non-operating state are changed in turn, and titanosilicate can be replaced while epoxidation of propylene is carried out in the reactors 1 in the operating state. In this way, titanosilicate can be replaced during the formation of propylene oxide, and therefore propylene oxide can be efficiently produced.

In addition, since the production equipment includes a sampling mechanism 5, the components of each reaction mixture discharged from each reactor 1 can be determined. In this way, the decrease in the activity of titanosilicate (deactivation state) can be understood, and therefore the replacement time of titanosilicate for each reactor 1 can be easily determined.

In addition, the production equipment 100 of the present embodiment includes a connecting line 4 that hydraulically connects the reactors 1 to each other and supplies the reaction mixture that is discharged from one of the connected reactors 1 and that contains the raw material for the reaction, to the other reactor 1, and a switching mechanism 6 connects only the reactors 1 in the operating state in series with the connecting line or lines 4.

According to such a configuration, only the reactors 1 in the operating state can be connected in series by the connecting line 4. In this way, the reaction feedstock is supplied to the reactors 1 in the operating state and thus supplied to a plurality of reactors 1, and therefore the formation of propylene oxide can be efficiently carried out.

In addition, each reactor 1 includes: a feed zone 1a, into which raw materials for the reaction are fed; and a discharge zone 1b, from which the reaction mixture is discharged, and the production equipment 100 includes thermometers that measure the internal temperature of the feed zone 1a and the discharge zone 1b, respectively.

In this document, the epoxidation reaction between peroxide and propylene is an exothermic reaction. Therefore, the decrease in the temperature difference between the discharge zone 1b and the feed zone 1a indicates a decrease in the activity of titanosilicate. Therefore, the decrease in the activity of titanosilicate can be determined from the temperatures measured by thermometers.

In addition, each reactor 1 includes a titanosilicate layer 1c formed by the stored titanosilicate, and the production equipment 100 includes a thermometer that measures the internal temperature of the titanosilicate layer 1c.

As described above, the epoxidation reaction between peroxide and propylene is an exothermic reaction. Therefore, the decrease in the temperature difference between the discharge zone 1b and the feed zone 1a indicates a decrease in the activity of titanosilicate. Therefore, the decrease in the activity of titanosilicate can be determined from the temperature measured by the thermometer.

In addition, each reactor 1 includes: a feed zone 1a, into which raw materials for the reaction are fed; and a discharge zone 1b, which discharges the reaction mixture, and the production equipment 100 includes pressure gauges that measure the internal pressure in the feed zone 1a and the discharge zone 1b, respectively.

According to this configuration, the change in the pressure loss of titanosilicate can be recorded from the pressures measured by the pressure gauges. By detecting the increase in pressure loss due to crushing of the catalyst, clogging of the material, or the like using the pressure gauges, it is possible to prevent the failure of equipment such as a pump used to supply raw materials for the reaction. The switching point of the reactor in the case where the decrease in the activity of titanosilicate is not the cause of switching can be easily determined from the pressure gauges.

In addition, in the production equipment 100 of the present embodiment, at least three reactors 1 have approximately the same size.

The production equipment 100 operates by switching the reactor 1 to the non-operating state and the reactor 1 to the operating state, so when the sizes of the reactors 1 are different, the adjustment of the holding time and temperature is difficult, therefore, it is difficult to control the operation, but when the sizes of the reactors 1 are approximately the same, the controllability of the operation can be improved.

In addition, each reactor 1 has a cylindrical shape, and when the inner diameter of the reactor 1 is taken to be D (m) and the height of the reactor 1 is taken to be L (m), L/D is from 0.5 to 20.

According to this configuration, since L/D is in the above-described ranges, the flow deviation of the liquid in the titanosilicate layer is suppressed, and therefore the decrease in the propylene oxide formation efficiency due to the flow deviation can be suppressed.

In addition, each reactor 1 includes a pressure relief valve capable of releasing internal pressure.

According to such a configuration, since each reactor 1 includes a pressure relief valve, the pressure in the reactor 1 can be released outside the reactor 1 even if the pressure in the reactor 1 increases to an unintended pressure. Thus, it is possible to prevent a breakdown of the reactor 1 or a decrease in the efficiency of propylene oxide formation caused by the internal pressure of the reactor 1.

In addition, the sampling mechanism 5 includes a sampling line 5a, which branches off from each discharge line 3 connected to each reactor 1, and which takes a portion of the reaction mixture, where the internal diameter of the sampling line 5a is smaller than the internal diameter of the discharge line 3 to which the sampling line 5a is connected.

According to this configuration, since the inner diameter of the sampling line 5a is smaller than the inner diameter of the discharging line 3 to which the sampling line 5a is connected, the flow rate of the reaction mixture flowing through the sampling line 5a is smaller than the flow rate of the reaction mixture flowing in the discharging line 3, and therefore sampling can be performed more safely than sampling the reaction mixture from the discharging line 3.

In addition, the sampling line 5a includes a sealing zone 5c capable of forming a tightly closed area for holding the reaction mixture, and has an opening for sampling on the sealing zone 5c.

According to such a configuration, since the sampling port is located in the sealing zone 5c included in the sampling line 5a, it is possible to take a sample of the reaction mixture retained in the sealing zone 5c. Therefore, sampling can be performed more safely than sampling from the reaction mixture flowing through the sampling line 5a.

In addition, the titanosilicate is preferably a silylated titanosilicate.

According to this configuration, the surface of titanosilicate becomes hydrophobic due to silylation, and therefore propylene, which is the raw material for the reaction, easily diffuses into titanosilicate, so that the reaction rate increases.

In addition, the titanosilicate is preferably a titanosilicate silylated with 1,1,1,3,3,3-hexamethyldisilazane.

1,1,1,3,3,3-Hexamethyldisilazane is a relatively inexpensive and easy to handle silylating agent, so silylated titanosilicate can be prepared relatively inexpensively and easily.

In addition, peroxide can be an organic peroxide.

Furthermore, the organic peroxide may be at least selected from the group consisting of cumene hydroperoxide, ethylbenzene hydroperoxide and tert-butyl hydroperoxide.

The method for producing propylene oxide according to the present embodiment is a method for producing propylene oxide by using the apparatus for producing propylene oxide described above and repeating (1) the first step of replacing titanosilicate in the reactor 1 in the non-working state while simultaneously feeding the reaction feedstock to the reactors 1 in the working state and performing epoxidation, and (2) the second step of switching the reactor 1 from the non-working state in which the titanosilicate has been exchanged to the working state, and switching one or more reactors 1 of the plurality of reactors 1 from the working state to the non-working state by means of the switching mechanism 6, and feeding the reaction feedstock to the reactors 1 in the working state and performing epoxidation, thereby performing epoxidation while changing the reactor 1 in the non-working state in turn to replace the titanosilicate, and the method further includes (3) the step of sampling from the sampling zone by means of the sampling mechanism 5 and checking the deactivation state of the titanosilicate.

According to such a configuration, by performing the above-described first step and second step, the reactor 1 in the non-operating state is replaced in turn, and titanosilicate can be replaced while epoxidation of propylene is carried out in the reactors 1 in the operating state. In this way, titanosilicate can be replaced during the formation of propylene oxide, and therefore propylene oxide can be efficiently produced.

In addition, since the production method includes a sampling step, the components of each reaction mixture discharged from each reactor 1 can be determined. In this way, the decrease in the activity of titanosilicate (deactivation state) can be determined, and therefore the replacement time of titanosilicate for each reactor 1 can be easily determined.

The method for producing propylene oxide according to the present embodiment is a method for producing propylene oxide using the propylene oxide production apparatus described above and repeating

(1) the first stage of replacing titanosilicate in reactor 1 in the non-working state with a series connection of only reactors 1 in the working state by a connecting line or lines 4 and feeding the reaction feedstock to reactors 1 in the working state and performing epoxidation, and

(2) a second step of switching the reactor 1 in the non-working state, in which the titanosilicate has been replaced, to the working state, switching one or more reactors 1 of the plurality of reactors 1 in the working state to the non-working state, connecting in series only the reactors 1 in the working state by the connecting line or lines 4, and feeding the reaction feedstock to the reactors 1 in the working state by means of the switching mechanism 6 and performing epoxidation, thereby performing epoxidation while switching the reactor 1 to the non-working state in turn to replace the titanosilicate, and the method further comprises

(3) the step of sampling a part of the reaction mixture using the sampling mechanism 5 and checking the deactivation status of the titanosilicate.

According to such a configuration, since the production method includes a first stage and a second stage, at least two reactors 1 in the operating state are connected in series by a connecting line 4, a reaction feedstock is supplied to at least one reactor 1 in the operating state from a feeding line 2, and a reaction feedstock is supplied to at least one reactor 1 in the operating state from a connecting line 4, where propylene, which is a reaction feedstock, passes through a plurality of reactors 1 and is epoxidized, and therefore propylene oxide can be efficiently produced.

In addition, since the production method includes a sampling step, the components of each reaction mixture discharged from each reactor 1 can be determined. In this way, the decrease in the activity of titanosilicate (deactivation state) can be determined, and therefore the replacement time of titanosilicate for each reactor 1 can be easily determined.

In the method for producing propylene oxide according to the present embodiment, the time for switching one or more reactors 1 to the non-operating state in the second stage is preferably determined in accordance with the deactivation status of the titanosilicate.

According to such a configuration, by determining the time of switching one or more reactors 1 to the non-operating state in the second stage according to the deactivation status of titanosilicate checked in the sampling stage, the replacement time of titanosilicate can be easily determined for each reactor 1.

The method for producing propylene oxide according to the present embodiment may include a step of separating alcohol from the reaction mixture.

In the method for producing propylene oxide according to the present embodiment, the second step includes a first feeding step consisting in switching the reactor 1 from the non-working state in which the titanosilicate has been exchanged to the working state and feeding the raw material for the reaction in the following order: propylene, then peroxide, and in the first feeding step, the ratio of the total volume flow rate (β) of propylene fed before the moment of feeding the peroxide into the reactor 1 switched from the non-working state to the working state to the volume (α) of titanosilicate stored in the reactor 1 transferred from the non-working state to the working state (β/α) is preferably set from 5 to 6000, more preferably from 600 to 3000.

According to such a configuration, in the alcohol conversion step, when converting the alcohol obtained by isolating from the reaction mixture obtained in the epoxidation step into another compound, it is possible to increase the conversion of the alcohol.

In the method for producing propylene oxide according to the present embodiment, the temperature of the titanosilicate layer at the outlet of the reactor 1, when feeding peroxide into the reactors 1 and switching the reactor 1 from the non-working state to the working state at the first feeding stage, is preferably set at a level of from 40 to 150°C.

According to such a configuration, the outlet temperature of the titanosilicate layer is preferably 40°C or higher from the viewpoint of ensuring efficient epoxidation reaction. The outlet temperature of the titanosilicate layer is preferably 150°C or lower from the viewpoint of suppressing the formation of a by-product in the epoxidation reaction. Examples of the by-product include substances formed by decomposing peroxide and substances obtained by converting propylene oxide, which is a product.

In the method for producing propylene oxide according to the present embodiment, the temperature of the titanosilicate at the outlet of the reactor 1 is preferably set at a level of 40 to 150°C during the feeding of only propylene into the reactor 1 in the first feeding stage.

According to this configuration, it is possible to prevent evaporation of propylene in reactor 1 and improve thermal efficiency.

It should be noted that the apparatus for producing propylene oxide and the method for producing propylene oxide of the present invention are not limited to the above-described embodiment, within which various modifications can be made without departing from the essence of the present invention. In addition, configurations, methods, and the like other than those described above can be arbitrarily adopted and combined, and the configuration, method, and the like of one embodiment described above can be applied to the configurations, methods, and the like in other embodiments.

For example, in the above-described embodiment, all the reactors 1 in the operating state are configured to be connected in series by a connecting line or lines 4 and carry out the epoxidation step, but the present invention is not limited to these, and, for example, as shown in Fig. 12A, all the reactors 1 in the operating state may be configured to be connected in parallel (in other words, in a connected state in which the reaction mixture is not fed from one reactor 1 to another reactor 1).

In addition, in the above-described embodiment, all of the plurality of reactors in the operating state are configured to be connected in series by the connecting line or lines 4 and perform the epoxidation step, but the present invention is not limited to these, and, for example, as shown in Fig. 12B to Fig. 13B, the plurality of reactors in the operating state may be configured such that the zones where the reactors 1 are connected in series by the connecting line or lines 4 and the zones where the reactors 1 are connected in parallel by the connecting line or lines 4 are mixed.

Further, in the above-described embodiment, all the reactors 1 are configured to have approximately the same dimensions, but the present invention is not limited thereto, and, for example, all the reactors 1 may be configured such that all the reactors 1 have different dimensions.

In addition, in the above-described embodiment, the feedstock for the reaction is supplied to each reactor 1 via one of the feed lines 2 and the connecting lines 4 in the epoxidation stage, but the present invention is not limited to them, and for example, the feedstock for the reaction can be supplied to the reactor 1 from both the feed line 2 and the connecting line 4.

In addition, in the above-described embodiment, a sampling port is provided on the sampling line 5a branching from the discharge line 3, but the present invention is not limited to these, and, for example, the configuration can be made such that the sampling port is provided on the discharge line 3 itself for sampling the reaction mixture directly from the discharge line 3.

In addition, in the above-described embodiment, a specific reactor 1 is configured to be the first reactor 1 among the plurality of reactors 1 connected in series, but the present invention is not limited thereto, and, for example, any reactor of the plurality of reactors 1 can be set as the main reactor 1 among the plurality of reactors 1 connected in series in the production equipment 100.

EXAMPLES

Hereinafter, the present invention will be described in more detail using working examples and experimental examples, but the present invention is not limited to the following working examples and experimental examples.

[Test 1]

1. Production facilities and materials used

•Reactors 1: Five reactors 1 are used in the above-described embodiment.

•Peroxide solution: Cumene solution (CUM) containing cumene hydroperoxide (CMHP).

• Propylene solution

2. Working example 1

In working example 1, the connection states between the reactors 1 are switched in the following order: the four-reactor operation shown in Fig. 14A, the five-reactor operation shown in Fig. 15C, and the four-reactor operation shown in Fig. 16. Specifically, the connection states are as follows.

<Working with four reactors>

As shown in Fig. 14A, one of the five reactors 1 is put into the non-operating state, and four reactors 1 are put into the operating state and are connected in series by connecting lines 4. Then, the CUM solution and the propylene solution are fed into the first or the frontmost reactor 1 and an epoxidation step is carried out as in the above-described embodiment, and thus propylene oxide (PO) is obtained.

In addition, samples of the reaction mixture are taken from sampling lines 5a, branching off from discharge lines 3, which are connected to reactors 1 corresponding to the third reactor 1 and the fourth reactor 1 of the series-connected reactors 1, and receiving part of the reaction mixture.

It should be noted that the ratio (outer diameter of discharge line 3)/(outer diameter of sampling line 5a) is equal to 13.

The conversion of SMNR in the third reactor 1, based on the SMNR supplied to the first reactor 1, is 98.1%. In addition, the conversion of SMNR in the fourth reactor 1, based on the SMNR supplied to the first reactor 1, is 99.3%.

<Working with three reactors>

The reactor 1 corresponding to the fourth reactor 1 of the four operating reactors is cut off from the other reactors 1 to switch the fourth reactor 1 to an inoperative state, as shown in Fig. 17B. Then, the CUM solution and the propylene solution are fed to the first reactor 1 and an epoxidation step is carried out as in the above-described embodiment, and thus propylene oxide (PO) is obtained.

In addition, samples of the reaction mixture are taken from the sampling line 5a, branching off from the discharge line 3, connected to the reactor 1, corresponding to the third reactor 1 of the reactors 1 connected in series, and receiving part of the reaction mixture.

The conversion of CMHP in the fourth reactor 1, based on the CMHP fed to the first reactor 1, is 98.1% (see Table 1 below).

<Four Reactor Operation>

As shown in Fig. 17C, the reactor 1 in the non-operating state is switched to the operating state, and four reactors 1 in the operating state are connected in series by connecting lines 4 so that the reactor 1 in the non-operating state switched to the operating state is used as the fourth reactor 1. Then, a CUM solution and a propylene solution are supplied to the first reactor 1 and an epoxidation step is carried out as in the above-described embodiment, and thus propylene oxide (PO) is obtained.

In addition, samples of the reaction mixture are taken from the sampling line 5a, branching off from the discharge line 3, connected to the reactor 1, corresponding to the fourth reactor 1 of the reactors 1 connected in series, and receiving part of the reaction mixture.

The conversion of SMNR in the fourth reactor 1, based on the SMNR fed to the first reactor 1, is 99.9%. In addition, the conversion of SMNR in the fifth reactor 1, based on the SMNR fed to the first reactor 1, is 100.0% (see Table 1 below).

<Working with four reactors>

As shown in Fig. 16, a reactor 1 corresponding to a fourth reactor 1 of five operating reactors 1 is cut off from the other reactors 1 to switch the reactor 1 to an inoperative state, and the switching is performed in such a manner that the reaction mixture discharged from the third reactor 1 is supplied to the fifth reactor 1, and thus the fifth reactor 1 is used as the fourth reactor 1. Then, a CUM solution and a propylene solution are supplied to the first reactor 1, and an epoxidation step is carried out as in the above-described embodiment, and thus propylene oxide (PO) is obtained.

In addition, samples of the reaction mixture were taken from the sampling line 5a, branching off from the discharge line 3, connected to the reactor 1, corresponding to the fourth reactor 1 of the reactors 1 connected in series, and receiving a portion of the reaction mixture.

The conversion of SMNR in the fourth reactor 1, based on the SMNR fed to the first reactor 1, is 99.9%.

3. Working example 2

In working example 2, the connection states between the reactors 1 are switched in the following order: the four-reactor operation shown in Fig. 17A, the three-reactor operation shown in Fig. 17B, and the four-reactor operation shown in Fig. 17C. Specifically, the connection states are as follows.

<Working with four reactors>

As shown in Fig. 17A, four reactors 1 in the operating state are connected in series by connecting lines 4. Then, a CUM solution and a propylene solution are fed into the first reactor 1 and an epoxidation step is carried out as in the above-described embodiment, and thus propylene oxide (PO) is obtained.

In addition, samples of the reaction mixture are taken from sampling lines 5a, branching off from discharge lines 3, connected to reactors 1, corresponding to the third reactor 1 and the fourth reactor 1 of the series-connected reactors 1, and receiving part of the reaction mixture.

It should be noted that the ratio (outer diameter of discharge line 3)/(outer diameter of sampling line 5a) is equal to 13.

The conversion of SMNR in the third reactor 1, based on the SMNR supplied to the first reactor 1, is 98.1%. In addition, the conversion of SMNR in the fourth reactor 1, based on the SMNR supplied to the first reactor 1, is 99.3%.

<Working with three reactors>

The reactor 1 corresponding to the fourth reactor 1 of the four operating reactors is cut off from the other reactors 1 to switch the fourth reactor 1 to an inoperative state, as shown in Fig. 17B. Then, the CUM solution and the propylene solution are fed to the first reactor 1 and an epoxidation step is carried out as in the above-described embodiment, and thus propylene oxide (PO) is obtained.

In addition, samples of the reaction mixture are taken from the sampling line 5a, branching off from the discharge line 3, connected to the reactor 1, corresponding to the third reactor 1 of the reactors 1 connected in series, and receiving part of the reaction mixture.

The conversion of CMHP in the fourth reactor 1, based on the CMHP fed to the first reactor 1, is 98.1% (see Table 1 below).

<Four Reactor Operation>

As shown in Fig. 17C, the reactor 1 in the non-operating state is switched to the operating state, and four reactors 1 in the operating state are connected in series by connecting lines 4 so that the reactor 1 in the non-operating state switched to the operating state is used as the second reactor 1. Then, a CUM solution and a propylene solution are supplied to the first reactor 1 and an epoxidation step is carried out as in the above-described embodiment, and thus propylene oxide (PO) is obtained.

In addition, samples of the reaction mixture are taken from the sampling line 5a, branching off from the discharge line 3, connected to the reactor 1, corresponding to the fourth reactor 1 of the reactors 1 connected in series, and receiving part of the reaction mixture.

The conversion of SMNR in the fourth reactor 1, based on the SMNR fed to the first reactor 1, is 99.9%.

[Table 1]

Transformation of the SMNR Working example 1
(when working with five reactors) 100% Working example 2
(when working with three reactors) 98%

[Test 2]

<Conversion of cumyl alcohol (CMA) and conversion of α-methylstyrene (AMS)>

= Experimental example 1 =

1. Stage of epoxidation reaction

A metal reactor (the metal reactor includes a protective tube with an outer diameter of 6 mm, wherein the protective tube includes a thermometer therein) with an inner diameter of 16 mm is filled with a catalyst (3.5 g or 10 ml of titanosilicate prepared according to Example 1 in JP 2004-195379 A). The catalyst is held in the form of a fixed bed having a filling length of 6 cm.

Propylene is fed at a rate of 0.8 g/min simultaneously with the start of heating the reactor in the electric furnace. The pressure in the reactor is increased by feeding propylene, and the PCV (flow controller) at the outlet is adjusted so that the pressure becomes 6 MPa-g. The temperature of the catalyst bed at the outlet reaches 120°C after 60 minutes. After that, the temperature of the electric furnace is adjusted so that the temperature of the catalyst bed at the outlet is 120°C, and propylene is fed for a total of 406 minutes. The ratio of the volume of propylene fed at this time/the volume of titanosilicate is 64.6.

After this, 3 wt.% CMHP/CUM/CMA is fed at a rate of 2.25 g/min. The temperature at the outlet of the catalyst bed after 60 minutes from the start of feeding 3 wt.% CMHP/CUM/CMA is 130°C. After this, the reaction is continued for 4 hours, and the operation is carried out until the temperature at the outlet of the catalyst bed reaches 130°C.

The entire volume of the solution from the start of feeding 3% by weight CMHP/CUM/CMA until the end of feeding is restored. The mass of the restored solution is 506 g.

Titration with HPO is performed and the concentration of CMHP is found to be 0.06%.

2. Simple distillation stage

A flask is charged with 490 g of the solution obtained in the epoxidation reaction stage. A Liebig condenser is attached to the flask to cool the distilled solution, and a receiver is installed to collect the distillate. The temperature of the Liebig condenser is set to -5 °C. The flask into which the reaction solution is charged is immersed in an oil bath and heated, and the temperature of the oil bath is increased until the temperature of the reaction solution reaches 160 °C. When the temperature reaches 160 °C, the temperature is maintained for 20 minutes, after which the flask is removed from the oil bath. The solution in the flask is cooled naturally, after which the solution cooled almost to room temperature is restored, and its weight is found to be 477 g. The proportion of distillate in the loaded solution is 2.7%.

3. Dehydration and hydrogenation stage

A metal reactor (the metal reactor includes a protective tube with an outer diameter of 3 mm, where the protective tube includes a thermometer inside it) with an inner diameter of 14 mm is filled with a catalyst (the mass of the catalyst is 3.0 g, the catalyst contains aluminum oxide and 0.05% by weight of palladium). The method of holding the catalyst is a fixed bed.

Liquid cumene is fed into the reactor to fill the reactor with liquid cumene. After that, the reactor is heated in an electric furnace so that the temperature of the inlet part of the catalyst bed reaches 220 °C, at which time gaseous nitrogen and liquid cumene are fed into the reactor at a rate of 84 NmL/min and 24 g/hour, respectively. After the temperature of the inlet zone of the catalyst bed is stabilized at 220 °C, gaseous nitrogen is switched to a hydrogen-containing gas to feed the hydrogen-containing gas at a rate of 72 NmL/min. The solution obtained in the simple distillation step is fed as a feed solution instead of liquid cumene into the reactor at a rate of 24 g/hour by switching the liquid feed lines substantially simultaneously with the switch to the hydrogen-containing gas. The liquid (reaction solution) discharged from the reactor between 165 and 180 minutes after the start of feeding the hydrogen gas is recovered. The concentrations of cumyl alcohol and α-methylstyrene are analyzed by gas chromatography for each feed solution and reaction solution.

The conversion of cumyl alcohol and the conversion of α-methylstyrene calculated from the concentrations of cumyl alcohol and the concentrations of α-methylstyrene in the feed solution and the reaction solution are 33% and 79%, respectively. Table 2 shows the results of the analysis. It should be noted that the average temperature of the catalyst bed measured during the reduction of the reaction solution is 224°C.

It should be noted that the conversion of cumyl alcohol and the conversion of α-methylstyrene are calculated according to the following equation (10) and equation (11).

Conversion of cumyl alcohol = {(concentration of cumyl alcohol in the initial solution) - (concentration of cumyl alcohol in the reaction solution)} / (concentration of cumyl alcohol in the initial solution) × 100 ∙∙∙(10)

Conversion of α-methylstyrene = {(concentration of cumyl alcohol in the feed solution) - (concentration of cumyl alcohol in the reaction solution) + (concentration of α-methylstyrene in the feed solution) - (concentration of α-methylstyrene in the reaction solution)}/{(concentration of cumyl alcohol in the feed solution) - (concentration of cumyl alcohol in the reaction solution) + (concentration of α-methylstyrene in the feed solution)} × 100 ∙∙∙(11)

= Experimental example 2 =

1. Stage of epoxidation reaction

Titanosilicate is used in an amount of 3.5 g, and the reactor is filled with titanosilicate under the same conditions as in Experimental Example 1.

Propylene is fed at a rate of 0.8 g/min simultaneously with the start of heating the reactor in the electric furnace. The pressure in the reactor is increased by feeding propylene, and the PCV (flow controller) at the outlet is adjusted so that the pressure becomes 6 MPa-g. The temperature of the catalyst bed at the outlet reaches 40°C after 10 minutes. After that, the temperature of the electric furnace is adjusted so that the temperature of the catalyst bed at the outlet is 40°C, and propylene is fed for a total of 405 minutes. The ratio of the volume of propylene supplied at this time/the volume of titanosilicate is 64.5. Except for the above, the epoxidation reaction step is carried out in the same manner as in Experimental Example 1.

The mass of the reconstituted solution is 513 g.

The reconstituted solution is titrated with HPO and the CMHP concentration is found to be 0.14%.

2. Simple distillation stage

A flask is charged with 485 g of the solution obtained in the epoxidation reaction stage. A Liebig condenser is attached to the flask to cool the distilled solution, and a receiver is installed to collect the distillate. The temperature of the Liebig condenser is set to -5 °C. The flask into which the reaction solution is charged is immersed in an oil bath and heated, and the temperature of the oil bath is increased until the temperature of the reaction solution reaches 160 °C. When the temperature reaches 160 °C, the temperature is maintained for 15 minutes, after which the flask is removed from the oil bath. The solution in the flask is cooled naturally, and then the solution cooled almost to room temperature is restored, and its weight is found to be 471 g. The proportion of distillate in the charged solution is 2.9%.

3. Dehydration and hydrogenation stage

The dehydration and hydrogenation step were carried out under the same conditions as in Experimental Example 1. Then, the liquid (reaction solution) discharged from the reactor between 165 and 180 minutes after the start of feeding the hydrogen gas was reduced. The concentrations of cumyl alcohol and α-methylstyrene in the feed solution and the reaction solution were analyzed in the same manner as in Experimental Example 1. The conversion of cumyl alcohol and the conversion of α-methylstyrene calculated from the concentrations of cumyl alcohol and the concentration of α-methylstyrene in the feed solution and the reaction solution were 32% and 79%, respectively. The average temperature of the catalyst bed measured during the extraction of the reaction solution was 225°C.

= Experimental example 3 =

1. Stage of epoxidation reaction

Titanosilicate is used in an amount of 3.6 g, and the reactor is filled with titanosilicate under the same conditions as in Experimental Example 1.

Propylene is fed at a rate of 0.8 g/min simultaneously with the start of heating the reactor in the electric furnace. The pressure in the reactor is increased by feeding propylene, and the PCV (flow controller) at the outlet is adjusted so that the pressure becomes 6 MPa-g. When propylene is fed for 26 minutes, the temperature of the catalyst bed at the outlet reaches 93°C. The ratio of the volume of propylene fed at this time/the volume of titanosilicate is 4.1. After that, 3 wt. % CMHP/CUM/CMA is fed at a rate of 2.25 g/min. The start time of feeding 3 wt. % CMHP/CUM/CMA is defined as the start of the reaction 0 min.

After 60 minutes from the start of feeding 3% by weight of CMHP/CUM/CMA, the temperature of the catalyst bed at the outlet is 130°C. The temperature of the electric furnace is adjusted so that the temperature of the catalyst bed at the outlet is 130°C, and the reaction is carried out for 4 hours.

The entire volume of the solution is recovered from the start of feeding 3% by weight of CMHP/CUM/CMA until the feeding is stopped. The mass of the solution recovered is 540 g. The recovered solution is titrated with HPO and the concentration of CMHP is found to be 0.08%.

2. Simple distillation stage

A flask is charged with 519 g of the solution obtained in the epoxidation reaction stage. A Liebig condenser is attached to the flask to cool the distilled solution, and a receiver is installed to collect the distillate. The temperature of the Liebig condenser is set to -5 °C. The flask into which the reaction solution is charged is immersed in an oil bath and heated, and the temperature of the oil bath is increased until the temperature of the reaction solution reaches 161 °C. When the temperature reaches 161 °C, the temperature is maintained for 20 minutes, after which the flask is removed from the oil bath. The solution in the flask is cooled naturally, and then the solution cooled to almost room temperature is restored, and its weight is found to be 507 g. The proportion of distillate in the charged solution is 2.3%.

3. Dehydration and hydrogenation stage

The dehydration and hydrogenation step were carried out under the same conditions as in Experimental Example 1. Then, the liquid (reaction solution) discharged from the reactor between 165 and 180 minutes after the start of feeding the hydrogen gas was reduced. The concentrations of cumyl alcohol and α-methylstyrene in the feed solution and the reaction solution were analyzed in the same manner as in Experimental Example 1. The conversion of cumyl alcohol and the conversion of α-methylstyrene calculated from the concentrations of cumyl alcohol and the concentration of α-methylstyrene in the feed solution and the reaction solution were 27% and 64%, respectively. The average temperature of the catalyst bed measured during the extraction of the reaction solution was 223°C.

[Table 2]

Experimental example 1 Experimental example 2 Experimental example 3 Conversion of cumyl alcohol 33% 32% 27% Conversion of α-methylstyrene 79% 79% 64%

<Conclusion>

The ratio of the total volume flow rate (β) of propylene supplied before feeding the peroxide into the reactor to the volume (α) of titanosilicate stored in the reactor (β/α) in the epoxidation reaction step is "64.6" in Experimental Example 1, "64.5" in Experimental Example 2, and "4.1" in Experimental Example 3. As can be seen from Table 2 above, the conversion of cumyl alcohol and the conversion of α-methylstyrene are higher in Experimental Examples 1 and 2 than in Experimental Example 3. That is, by carrying out the epoxidation reaction step by setting the ratio to 5 or more, the respective conversions in the dehydration and hydrogenation steps can be improved.

LIST OF REFERENCE SIGNS

1: Reactor

1a: Feeding area

1b: Unloading area

1c: Titanosilicate layer

2: Serving line

3: Unloading line

4: Connecting line

5: Sampling mechanism

5a: Sampling line

5b: Sampling valve

5c: Compaction zone

5d: Shut-off valve

6: Switching mechanism

6a: Changeover valve

10: Epoxidation reaction zone

100: Production equipment

Claims (46)

1. An installation for producing propylene oxide, designed with the possibility of producing propylene oxide by epoxidizing propylene using peroxide in the presence of titanosilicate, wherein the installation includes: at least three reactors designed with the possibility of storing titanosilicate and feeding it as raw material for the reaction of propylene and peroxide; a feed line configured to feed reaction feedstock that has not yet been fed to each reactor into each reactor; a discharge line which is connected to each reactor and is configured to discharge the reaction mixture containing propylene oxide from each reactor; a switching mechanism configured to switch the state of each reactor between an operating state in which the feedstock for the reaction is supplied and the epoxidation reaction is carried out, and a non-operating state in which the feedstock for the reaction is turned off, configured to alternate the reactor in the non-operating state in turn and configured to perform the switching in such a way that only the reactors in the operating state are hydraulically connected, in series or in parallel, with the feedstock for the reaction being supplied to the reactors in the operating state; and a sampling mechanism configured to sample a portion of the reaction mixture from each discharge line connected to each reactor, where each reactor contains: a feed zone into which the raw material for the reaction is fed; and an unloading zone from which the reaction mixture is unloaded, and additionally contains thermometers that measure the internal temperature of the feed zone and the unloading zone, respectively. 2. The apparatus according to claim 1, further comprising a connecting line that hydraulically connects the reactors to each other and that feeds the reaction mixture discharged from one of the connected reactors to another reactor, where the reaction mixture contains feedstock for the reaction, where The switching mechanism connects only the reactors in working condition, in series, by a connecting line or lines. 3. An installation according to any of paragraphs 1, 2, in which each reactor contains a titanosilicate layer formed by the stored titanosilicate, and The installation additionally contains a thermometer that measures the internal temperature of the titanosilicate layer. 4. An installation according to any one of paragraphs 1-3, in which each reactor comprises a feed zone into which the feedstock for the reaction is fed; and a discharge zone from which the reaction mixture is discharged, and The installation additionally contains pressure gauges that measure the internal pressure in the feed zone and the discharge zone, respectively. 5. An installation according to any one of claims 1 to 4, wherein at least three reactors have substantially the same size. 6. An installation according to any one of paragraphs 1-5, in which each reactor has a cylindrical shape, and when the internal diameter of the reactor is taken equal to D (m) and the height of the reactor is taken equal to L (m), L/D is from 0.5 to 20. 7. An installation according to any one of claims 1 to 6, wherein each reactor comprises a pressure relief valve capable of releasing the internal pressure. 8. An installation according to any one of paragraphs 1-7, in which the sampling mechanism includes a sampling line that branches off from each discharge line connected to each reactor and that receives a portion of the reaction mixture, and the diameter of the sampling line is smaller than the internal diameter of the discharge line to which the sampling line is connected. 9. The apparatus according to claim 8, wherein the sampling line comprises a sealing zone capable of forming a hermetically sealed area for holding the reaction mixture, and has an opening for sampling in the sealing zone. 10. An installation according to any one of claims 1 to 9, wherein the titanosilicate is a silylated titanosilicate. 11. The installation according to claim 10, wherein the titanosilicate is a titanosilicate silylated with 1,1,1,3,3,3-hexamethyldisilazane. 12. An installation according to any one of claims 1 to 11, wherein the peroxide is an organic peroxide. 13. The apparatus for producing propylene oxide according to claim 12, wherein the organic peroxide is at least selected from the group consisting of cumene hydroperoxide, ethylbenzene hydroperoxide and tert-butyl hydroperoxide. 14. A method for producing propylene oxide using a plant for producing propylene oxide according to claim 1, comprising: (1) the first stage of replacing titanosilicate in the reactor in a non-working state when feeding raw materials for the reaction to the reactors in a working state and carrying out epoxidation; (2) a second step of switching the reactor from the non-operating state in which the titanosilicate has been replaced to the operating state, and switching one or more reactors from the plurality of reactors in the operating state to the non-operating state by a switching mechanism, and feeding the reaction feedstock to the reactors in the operating state and performing epoxidation; and (3) the stage of sampling a part of the reaction mixture using a sampling mechanism and checking the deactivation state of the titanosilicate, where the first stage and the second stage are repeated, and thus the epoxidation is carried out while the reactor, which is to be put out of operation, is changed in turn to replace the titanosilicate. 15. A method for producing propylene oxide using a plant for producing propylene oxide according to item 2, comprising: (1) the first stage of replacing titanosilicate in a reactor in an inoperative state by connecting in series only the reactors in the operational state by a connecting line or lines, and feeding the feedstock for the reaction to the reactors in the operational state, and carrying out epoxidation; (2) a second step of switching the reactor from the non-operating state in which the titanosilicate has been replaced to the operating state, switching one or more reactors from a plurality of reactors in the operating state to the non-operating state, sequentially connecting only the reactors in the operating state by a connecting line or lines, and feeding the reaction feedstock to the reactors in the operating state by a switching mechanism and performing epoxidation; and (3) the stage of sampling a part of the reaction mixture using a sampling mechanism and checking the deactivation state of the titanosilicate, where the first stage and the second stage are repeated, and thus the epoxidation is carried out while the reactor, which is to be put out of operation, is changed in turn to replace the titanosilicate. 16. The method according to claim 14 or 15, wherein the time of switching one or more reactors to a non-operating state in the second stage is determined in accordance with the deactivation status of the titanosilicate. 17. The method according to any one of paragraphs 14-16, further comprising the step of isolating alcohol from the reaction mixture. 18. The method according to claim 14 or 15, wherein the second stage includes the first stage of feeding the reactor from the non-working state, in which the titanosilicate has been replaced, to the working state and feeding the starting materials for the reaction in the following order: propylene, then peroxide, and at the first stage of feeding, the ratio of the total volume flow rate (β) of propylene fed before the peroxide is fed into the reactor switched from the non-working state to the working state, to the volume (α) of titanosilicate stored in the reactor switched from the non-working state to the working state (β/α), is from 5 to 6000. 19. The method according to claim 18, wherein at the first stage of feeding the temperature of the titanosilicate layer at the outlet of the reactor is set at a level of 40 to 150°C when the peroxide is fed into the reactor, and the reactor is switched from an inoperative state to an operational state. 20. The method according to claim 18, wherein at the first stage of feeding the temperature of the titanosilicate layer at the outlet of the reactor is set at a level of 40 to 150°C when only propylene is fed into the reactor.

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