KR20170129909A - Integrated Method and Apparatus for the Production of Aryl Carbonates - Google Patents

Abstract

In one embodiment, a method for making an alkyl aryl carbonate comprises providing a purified dialkyl carbonate stream and a first purified alkanol stream; Reacting the purified dialkyl carbonate stream to produce a diaryl carbonate stream and (i) an aromatic alcohol stream and a second dialkyl carbonate stream, or (ii) a second dialkyl carbonate stream, and the second dialkyl carbonate Separating the aromatic alcohol from the stream to produce an aromatic alcohol stream comprising said aromatic alcohol; Directing a first portion of the aromatic alcohol stream to a dialkyl carbonate purification unit; Reacting the second dialkyl carbonate stream, the second portion of the aromatic alcohol stream and the first aromatic alcohol feed stream to produce an alkanol stream and an alkyl aryl carbonate stream; And purifying the alkanol stream and the first partial stream in the dialkyl carbonate purification unit to provide the purified dialkyl carbonate stream and the first purified alkanol stream, And extracting the carbonate with an aromatic alcohol.

Description

Integrated Method and Apparatus for the Production of Aryl Carbonates

Cross-reference to related application

We claim the benefit of European Application No. 15382137, filed March 23, 2015. Related Applications are incorporated herein by reference in their entirety.

This disclosure generally relates to methods and apparatus for the production of arylcarbonates such as alkylaryl carbonates and diaryl carbonates, and particularly to methods and apparatus for the production of aryl carbonates.

Diaryl carbonates, such as diphenyl carbonate (DPC), are important reactants in the production of polycarbonates. Polycarbonates can be prepared by polymerization of diaryl carbonates, such as aromatic dihydroxy compounds with DPC, such as bisphenol A (BPA). Polycarbonates are valuable materials because of their physical and optical properties. As the use of polycarbonate increases, the efficient production of diaryl carbonates has become of greater importance. The phosgene-free process comprises reacting a dialkyl carbonate, such as dimethyl carbonate (DMC), with an aromatic alcohol, such as phenol, in the presence of an ester exchange catalyst to form an alkylaryl carbonate (e.g., phenylmethyl carbonate (PMC) And a first step of producing an alcohol (alkanol) (for example, methanol or ethanol). In the second step, the two molecules of the alkylaryl carbonate undergo a disproportionation reaction to produce one molecule of diaryl carbonate (e.g., DPC) and one molecule of the starting material dialkyl carbonate (e.g., DMC).

Phosgene-free industrial methods for preparing dialkyl carbonate starting materials include oxidative carbonylation of alkanols, alkylnitrate carbonylations, direct synthesis from CO ₂ and epoxidation carbonylation of alcohols. In the epoxidation carbonylation process, an alkylene oxide (e.g., ethylene oxide) is reacted with carbon dioxide in the presence of a catalyst to produce an alkylene carbonate (e.g., ethylene carbonate or propylene carbonate) (E. G., Dimethyl carbonate) and alkylene glycols (e. G., Ethylene glycol) by transesterification with water (e. G., Methanol or ethanol), which by itself is a valuable by-product.

Despite intensive work to develop and improve such phosgene-free industrial processes, there is a need for methods and apparatus for the production of diaryl carbonates with reduced energy consumption while still producing high quality diaryl carbonates, especially DPC. There is a continuing need. This would be a further advantage if the method and apparatus could be adopted at lower investment costs.

Methods and systems for making aryl carbonates are disclosed herein.

In one embodiment, a method for preparing an alkyl aryl carbonate comprises reacting an alkylene carbonate and an alkanol in a dialkyl carbonate reactor in the presence of a first ester exchange catalyst to produce a first alkylene carbonate and an unreacted alkanol, A dialkyl carbonate product stream, and an alkylene glycol product stream comprising an alkylene glycol and an unreacted alkanol; Purifying the first dialkyl carbonate product stream in a dialkyl carbonate purification unit to provide a purified dialkyl carbonate stream and a first purified alkanol stream; Reacting the purified dialkyl carbonate stream in a diaryl carbonate reactor in the presence of a second ester exchange catalyst to produce a diaryl carbonate product stream comprising a diaryl carbonate product by disproportionation, and (i) An aromatic alcohol product stream, a second dialkyl carbonate product stream comprising said dialkyl carbonate and alkyl aryl ether, or (ii) a second dialkyl carbonate product stream comprising said dialkyl carbonate, an aromatic alcohol product and an alkyl aryl ether Separating the aromatic alcohol product from the second dialkyl carbonate product stream to produce an aromatic alcohol product stream comprising the aromatic alcohol product; (X wt%) as the first partial stream of the aromatic alcohol product stream to the dialkyl carbonate purification unit and adding a predetermined amount (100 wt% -X wt%) of the aromatic alcohol product stream as the second partial stream, To an alkyl aryl carbonate reactor wherein X wt% is greater than 0; Reacting the second dialkyl carbonate product stream, the second partial stream and the first aromatic alcohol feed stream in an alkylaryl carbonate reactor in the presence of a second transesterification catalyst to produce an alkanol product and an unreacted dialkyl carbonate, Producing an alkylaryl carbonate product stream comprising an alkanol product stream, and an alkyl aryl carbonate product and an unreacted aromatic alcohol; And purifying the alkanol product stream and the first partial stream in the dialkyl carbonate purification unit to provide the purified dialkyl carbonate stream and the first purified alkanol stream, And extracting the dialkyl carbonate using an aromatic alcohol.

In another embodiment, a system for the production of an alkyl aryl carbonate comprises a dialkyl carbonate reactor, an alkylaryl carbonate reactor, a dialkyl carbonate purification unit, and a diaryl carbonate reactor. The dialkyl carbonate reactor comprises an alkanol inlet, an alkylene carbonate inlet, an alkylene diol outlet, and a first alkanol / dialkyl carbonate outlet in fluid communication with a dialkyl carbonate inlet of the dialkyl carbonate purification unit. The dialkyl carbonate purification unit comprises a dialkyl carbonate inlet, a first purified alkanol outlet, a purified dialkyl carbonate outlet; And a unit aromatic alcohol inlet. The diaryl carbonate reactor comprises a purified dialkyl carbonate inlet in fluid communication with the purified dialkyl carbonate outlet, an alkylaryl ether / dialkyl carbonate outlet in fluid communication with the alkylaryl ether / dialkyl carbonate inlet of the alkylaryl carbonate reactor, a dialkyl carbonate / A unit aromatic alcohol inlet of the carbonate refining unit, and optionally an aromatic alcohol outlet in fluid communication with the reactor aromatic alcohol inlet of the alkylaryl carbonate reactor, and a diaryl outlet. The alkylaryl carbonate reactor comprises a reactor aromatic alcohol inlet, an alkylaryl ether / dialkyl carbonate inlet in fluid communication with the alkylaryl ether / dialkyl carbonate outlet of the diaryl carbonate reactor, an alkanol / dialkyl carbonate inlet of the dialkyl carbonate purification unit A second alkanol / dialkyl carbonate outlet in fluid communication, and an alkyl aryl carbonate outlet.

In another embodiment, a system for the production of alkyl aryl carbonate comprises a dialkyl carbonate reactor, an alkylaryl carbonate reactor, a dialkyl carbonate purification unit, a diaryl carbonate reactor; And an aromatic alcohol separation unit. The dialkyl carbonate reactor comprises an alkanol inlet, an alkylene carbonate inlet, an alkylene diol outlet, and a first alkanol / dialkyl carbonate outlet in fluid communication with a dialkyl carbonate inlet of the dialkyl carbonate purification unit. The dialkyl carbonate purification unit comprises a dialkyl carbonate inlet, a first purified alkanol outlet, a purified dialkyl carbonate outlet; And a unit aromatic alcohol inlet. The diaryl carbonate reactor comprises a refined dialkyl carbonate inlet in fluid communication with the purified dialkyl carbonate outlet, an aromatic alcohol separation unit wherein the aromatic alcohol separation unit comprises an aromatic outlet in fluid communication with the unit aromatic alcohol inlet, An alkylaryl ether / dialkyl carbonate outlet in fluid communication with a separation inlet of a separate alkylaryl ether / dialkyl carbonate outlet in communication, and a diaryl outlet. The alkylaryl carbonate reactor comprises a reactor aromatic alcohol inlet, a second alkanol / dialkyl carbonate outlet in fluid communication with the alkanol / dialkyl carbonate inlet of the dialkyl carbonate purification unit, and an alkyl aryl carbonate outlet.

The above-described and other features are illustrated by the following drawings and detailed description.

The following drawings are illustrative and non-limiting implementations:
Figure 1 diagrammatically illustrates one embodiment of a prior art plant design for the production of dialkyl and diaryl carbonates;
Figure 2 diagrammatically illustrates an embodiment of a plant design for the production of dialkyl carbonates, alkyl aryl carbonates and diaryl carbonates;
Figure 3 diagrammatically illustrates one embodiment of a plant design of dialkyl carbonate, alkyl aryl carbonate and diaryl carbonate.

As noted above, epoxidation carbonylation processes can be used, for example, in the preparation of dialkyl carbonates, wherein an alkylene oxide is reacted with carbon dioxide in the presence of a catalyst to produce an alkylene carbonate, To produce dialkyl carbonates and alkylene glycols. The dialkyl carbonate can then be reacted with an aromatic alcohol in the presence of an ester exchange catalyst to produce an alkylaryl carbonate and an alkanol. Diaryl carbonates can then be prepared using disproportionation of alkyl aryl carbonates. One illustrative prior art system 100 is shown schematically in Figure 1, which is shown in Figure 1 to perform transesterification of an alkylene carbonate in stream I with an alkanol in stream J to produce a dialkyl carbonate stream A An alkylcarbonate reactor 110; An alkyl aryl carbonate reactor (140) for performing an ester exchange of the dialkyl carbonate to produce an alkyl aryl carbonate stream (B); And a diaryl carbonate reactor 180 for carrying out the disproportionation of the alkyl aryl polycarbonate to produce the diaryl carbonate stream C. The various limitations and conditions associated with this method have led to relatively complicated devices for performing them.

For example, a molar excess of alkanol is typically used to overcome this thermodynamic limitation, since the yield of the transesterification reaction is strongly limited by the equilibrium conversion rate. Unreacted alkanols in dialkyl carbonate stream A can be recovered and recycled as distillate stream D in a separate distillation unit 120, but need to be highly pure. Furthermore, distillation to purify the alcohol and to produce the dialkyl carbonate stream H can not be efficiently achieved at atmospheric pressure, where alkanol and dialkyl carbonate form an azeotropic mixture at low temperatures and pressures (e.g., Methanol or ethanol and dimethyl carbonate form an azeotropic mixture at 63 degrees centigrade (C) and 1 bar (absolute (abs)). Thus, operation at higher pressures is required to enrich the methanol or ethanol content in the purification column as described, for example, in US 8,049,028. Another example is to transalkylate a dialkyl carbonate stream with an aromatic alcohol to produce an alkyl aryl carbonate. In this process, the dialkyl carbonate stream H is transesterified in the alkylaryl carbonate reactor 140, and the by-product stream E containing the unreacted dialkyl carbonate, alkanol is distilled again under pressure in the high pressure distillation column 150, The pure alkanol stream F and the unreacted dialkyl carbonate stream G are recovered. In some embodiments, the byproduct stream E further comprises a minor amount (less than 2 weight percent (wt%)) of aromatic alcohol or a greater amount, such as 5 to 30 wt% of the by-

Methods and apparatus for the production of alkyl aryl carbonates have been found to be able to improve the overall efficiency of the process, including reducing energy consumption and initial capital costs. In particular, the improvement can include the incorporation of dialkyl carbonate and alkyl aryl carbonate manufacturing methods by combining the purification column used in the production of the dialkyl carbonate and alkylaryl carbonate plant into a single distillation column. That is, the output stream from the dialkyl carbonate production column and the alkyl aryl carbonate production column distillate is sent to a single separation unit. The output from this unit is a dialkyl carbonate-rich stream, which can be advantageously used directly in the production of alkyl aryl carbonates and purified alkanols. The purity of the alkanol can be adjusted by adjusting the operating conditions of the separation unit. Thus, the number of distillation columns required for refining the product and recycling the unreacted reactants can be reduced. When used in the preparation of diaryl carbonates, the overall process is more efficient and has a reduced cost.

A method for the production of an alkyl aryl carbonate may comprise directing a purified dialkyl carbonate stream from a dialkyl carbonate purification unit to a diaryl carbonate reactor wherein the diaryl carbonate reactor comprises an aromatic alcohol product comprising an aromatic alcohol It was also found that the stream could be further purified. At least a portion of the aromatic alcohol from the diaryl carbonate reactor may be added to the single diaryl carbonate purification unit and the alkyl aryl carbonate reactor. In this way, the aromatic alcohols prepared in the diaryl carbonate reactor can be used to destroy the azeotrope mixture formed between the dialkyl carbonate and the alkyl alcohol (which is otherwise difficult to separate).

A more complete understanding of the components, methods, and apparatus described herein may be gained with reference to the accompanying FIGS. 2 and 3, which are schematic representations based on convenience and ease of demonstration of this disclosure, And are not intended to represent the relative sizes and dimensions of the components thereof and / or to limit or limit the scope of the exemplary embodiments. Although specific terms are used in the following description for clarity, these terms are intended to refer only to the specific structures of the embodiments selected for illustration in the figures and are not intended to limit or limit the scope of the disclosure contents.

Figures 2 and 3 schematically illustrate systems 200 and 300 that include three reactors (e.g., a reactive distillation column) and one dialkyl refining unit for purifying distillates from two different reacting columns Respectively. Previously, two or more columns (one in a dialkyl carbonate manufacturing facility and one in an alkyl aryl carbonate or diaryl carbonate manufacturing facility) were typically required. For example, the locations of the various streams / lines as described herein as present in the "top", "middle", "bottom", or "sides" of a particular column may be determined by the actual location at which the material is introduced or recovered, It will be understood by those skilled in the art that it will be understood that it is relative to the conditions under which it is held. For example, a stream injected into the "bottom" of a column may actually be injected into multiple stages of the drainage contain- ing the reboiler of that column, and the line / The stream may actually exit the various stages below the upper stage, including the condenser of that column. Accordingly, these terms are included herein for ease of reference for describing general directions for various columns and lines / streams, and these terms are not intended to be limited to one exact position. It should also be understood that although Figures 2 and 3 and the accompanying description may illustrate a single container, e. G. A reaction container, a refill container or a mixing container, for illustrative purposes, it is understood that multiple containers in series or parallel, do.

The system 300 as shown in FIG. 3 is similar to the system 300 shown in FIG. 3, except that the aromatic alcohol can be separated from the diaryl carbonate reactor 380 and the zeolite of the dialkyl carbonate and alkanol introduced into the dialkyl carbonate purification unit 360 Is similar to the system 200 except that it can be used to destroy the mixture. These aromatic alcohols can operate in a loop that can cycle through the first partial stream 30, the purified dialkyl carbonate stream 16, and the aromatic alcohol product stream 28. Instead of removing the aromatic alcohol product stream 28 from the middle portion of the diaryl carbonate reactor 380, the aromatic alcohol may be removed along with the second dialkyl carbonate product stream 34, followed by additional separation units, e.g., It can be separated in a distillation column. 3 also shows that the purified dialkyl carbonate stream 16 of the dialkyl carbonate purge unit 360 is fed to the diaryl carbonate reactor 380 and the diaryl carbonate reactor 380 is fed to the aromatic alcohol product stream 28 It is noted that only one or the other of the above conditions may be applied to the system 200

Reactors 210, 310, 240, 340, 280, and 380 may each independently be a reactive distillation column, each having a rectifying section and a reaction section where a chemical reaction takes place. Generally, the reaction section of the column is provided with at least one reactive distillation stage equipped with a packing or a fixed internal structure (wherein the "internal structure" refers to the portion in the distillation column where the gas and liquid are actually brought into contact with one another) can do. For example, the reaction section of the reactive distillation column may provide five or more, such as 5 to 60, reactive stages, specifically 10 or more, such as 10 to 40 distillation stages. Known dumped packings and / or packed packings may be used. In particular, packings with large surface area, good wetting and residence times of the liquid phase, such as, for example, Novolax rings, CY packings may be used. Fixed internal structures, such as tray columns, may also be used, and specific examples include sieve trays, valve trays, and bubble-cap trays.

Systems 200 and 300 as shown in Figures 2 and 3, respectively, additionally include a dialkyl carbonate purge unit 260, a dialkyl carbonate purge unit 360 and optional alkylene glycol purge units 230 and 330, Lt; / RTI > Each of said purification units may be independently a high pressure distillation column. These columns can perform separation of materials based on boiling point without propelling concurrent chemical reactions. The dialkyl carbonate reactor 210, the alkyl aryl carbonate reactor 240 and the diaryl carbonate reactor 280 and the dialkyl carbonate purge unit 260 and the alkylene glycol purifier unit 230 may comprise reactants and / Can be interconnected by a series of feed / recycle lines that serve to transport the stream. The dialkyl carbonate reactor 310, the alkylaryl carbonate reactor 340 and the diaryl carbonate reactor 380 and the dialkyl carbonate purification unit 360 and the alkylene glycol purification unit 330 contain reactants and / Lt; RTI ID = 0.0 > supply / recycle < / RTI > The direction of flow for each line is specified in the figure. A variety of valves, heaters, and other accessories may optionally be included with the feed / recycle line shown in the figure when customizing the design to a particular installation.

Figures 2 and 3 can be used according to the preparation of diaryl carbonates, specifically DPC, according to embodiments disclosed herein. Although the description of the method relates to a continuous method, any one or more of the steps may be performed in a batch manner. In operation of the method, the alkylene carbonate stream 18 comprises an alkylene carbonate, such as ethylene carbonate or propylene carbonate (EC), and the alkanol stream 20 comprises an alkanol, such as methanol or ethanol, Can be new, can be recycled, or a combination thereof. If the catalyst is homogeneous, the catalyst may be supplied with the alkylene carbonate or alkanol, or may be fed at a different location than the two. If the catalyst is heterogeneous, the catalyst may be packed in the desired amount at the desired location in the reactor. In one embodiment, the catalyst is a heterogeneous catalyst immobilized on a catalyst bed.

The alkylene carbonate and alkanol may be continuously fed into the dialkyl carbonate reactor 210, 310 (which is a reactive distillation column as shown). Ester exchange is carried out in the presence of a catalyst to produce diols, specifically ethylene glycol, and dialkyl carbonates, specifically dimethyl carbonate. It is recognized that conditions in the reactor, such as temperature, pressure, and molar ratio of reactant feed, can be selected and optimized to reduce or otherwise control the concentration of the product without undue experimentation.

The high boiling point reaction mixture (alkylene glycol product stream 22) containing the diol can be continuously withdrawn from the lower portion of the dialkyl carbonate reactors 210 and 310 in liquid form and the dialkyl carbonate product & The low boiling point reaction mixture (first dialkyl carbonate product stream (2)) containing the reactive alkanol can be continuously withdrawn from the upper portion of the gaseous column (210, 310).

The first dialkyl carbonate product stream (2) may be fed into a dialkyl carbonate purification unit (260, 360) (e.g., a distillation column as described in more detail below) (The first purified alkanol stream 12) containing the lower portion of the column and the lower column component (the purified dialkyl carbonate stream 16) containing the dialkyl carbonate as the main component. The first purified alkanol stream 12 may optionally be recycled to the dialkyl carbonate reactor 210,310 and the purified dialkyl carbonate 16 may be recycled to the alkylaryl carbonate reactor 240 Or the diaryl carbonate reactor 380 (as illustrated in Figure 3).

Optionally, the alkylene glycol product stream 22 may be fed to an alkylene glycol purification unit 230, 330 to provide a purified alkylene glycol stream 8 and a second purified alkanol stream 14. Here, the unreacted alkanol can be separated from the produced diol and recycled, for example, to the dialkyl carbonate reactor 210, 310.

The reaction for preparing the alkyl aryl carbonate, specifically methyl phenyl carbonate, can be carried out in an alkyl aryl carbonate reactor (240, 340), for example a reactive distillation column as shown. The first aromatic alcohol feed stream 24 may comprise an ester exchange catalyst and an aromatic alcohol, such as phenol, which may be new, or may be recycled, or a combination thereof. For example, the recycled aromatic alcohol (dialkyl carbonate product stream 26) may be used in addition to or in place of the new aromatic alcohol. The other starting material, dialkyl carbonate (purified dialkyl carbonate stream 16) may comprise recycled material from the dialkyl carbonate purification unit 260.

The purified dialkyl carbonate stream 16 may be fed, for example, to the bottom of an alkyl aryl carbonate reactor 240, specifically a reboiler. The purified dialkyl carbonate stream 16 may be liquid or vapor depending on the type of reboiler used. For example, if an external reboiler, such as a kettle reboiler, is used, the purified dialkyl carbonate stream 16 may be fed to the alkylaryl carbonate reactor 240 as a vapor.

The first aromatic alcohol feed stream 24 may be fed as a liquid, for example, to an intermediate section of an alkylaryl carbonate reactor 240, 340, more specifically at a location at or near the top of the reactive distillation section. The feed rate of the stream fed into the alkylaryl carbonate reactor (240, 340) is such that the molar ratio of dialkyl carbonate to aromatic alcohol introduced into the alkylaryl carbonate reactor (240, 340) is between 0.1 and 10, Specifically, it may be from 0.5 to 3.

The alkyl aryl carbonate reactor 340 may be operated in the presence of excess phenol. For example, the feed rate of the stream introduced into the alkylaryl carbonate reactor 340 may be controlled such that the molar ratio of dialkyl carbonate to aromatic alcohol introduced into the alkylaryl carbonate reactor 340 is from 1: 3 to 1: 1.5, 2.5 to 1: 1.5. In this way it has surprisingly been found that the alkylaryl carbonate reactor 340 can operate at reduced pressures of 50 to 150 kilopascals (kPa) (g), specifically 80 to 125 kPa (g). The alkylaryl carbonate reactor 340 can operate at a temperature of 140 degrees Celsius or more, 140 to 500 degrees Celsius, specifically 200 to 450 degrees Celsius, more specifically 350 to 350 degrees Celsius.

The dialkyl carbonate can be provided in excess via the purified dialkyl carbonate stream (16) since the dialkyl carbonate can serve both as a reactant and as a stripping agent, Thereby facilitating the removal of the alkanol. Such removal can increase the rate of production of the alkyl aryl carbonate in the alkyl aryl carbonate reactor (240, 340). The transesterification reaction may be carried out in an alkyl aryl carbonate reactor (240, 340), for example at a temperature above 100 ° C, specifically above 130 ° C, more specifically above 140 ° C. Examples of the temperature range for carrying out the reaction include 100 占 폚 to 300 占 폚, specifically 110 占 폚 to 270 占 폚, more specifically 120 占 폚 to 250 占 폚. The operating pressure at the top of the alkylaryl carbonate reactor 240, 340 is greater than or equal to 0.5 bar g (50 kPa (g)), specifically greater than or equal to 2 bar g (200 kPa (g) Specifically, it may be 3 bar (g) (300 kPa (g)) or more.

The reactant product and the unreacted starting material may be removed from the alkylaryl carbonate reactors 240, 340 in a continuous manner via the alkanol product stream 10 and the alkyl aryl carbonate product stream 4. The alkanol product stream 10 which may be withdrawn from the top of the alkylaryl carbonate reactor 240, 340 is the unreacted dialkyl carbonate and the alkanol produced in the transesterification reaction as well as other reactants and by-products such as aromatic alcohols . In one embodiment, the alkylaryl carbonate reactor 240, 340 has a rectification section and a reaction section. The rectifying section is the upper section of the reactors 240, 340 above at least one feed point of the reactants, and may include, for example, a packing or a tray. The chemical reaction is generally considered not to occur in the rectification section. The presence of the rectifying section may affect the amount of aromatic alcohol in the alkanol product stream 10. Alternatively, the alkanol product stream 10 optionally passes through a rectification column (not shown), which is initially for processing and recovery. The rectification section and the optional rectification column may also be equipped with a packing or a fixed internal structure to provide, for example, three or more, specifically five or more, and more particularly, five to fifty distillation stages. For example, dumped packings and / or packed packings may be used. The temperature profile of the optional rectification column (not shown in FIGS. 2 and 3) may be at least 10 ° C, in particular at least 50 ° C. An example of a temperature range for a temperature profile in an arbitrary rectification column is 10 占 폚 to 200 占 폚, specifically 50 占 폚 to 110 占 폚. The operating pressure in an optional rectification column may be greater than or equal to 0.1 bar (g) (10 kPa (g)), specifically greater than 0.5 bar (g) (50 kPa (g)). Examples of pressure ranges include 0.1 to 10 bar (g) (1000 kPa (g)), specifically 0.5 to 3 bar (g) (50 to 300 kPa (g)).

The alkylaryl carbonate product stream (4), which may be withdrawn from the bottom of the alkylaryl carbonate reactor (240, 340), for example, from the reboiler of the alkylaryl carbonate reactor (240, 340), may be an unreacted starting material, Ether and an alkyl aryl carbonate prepared in an alkyl aryl carbonate reactor (240, 340) in combination with a catalyst. As shown in Figures 2 and 3, the alkylaryl carbonate product stream (4) is suitable for use in the preparation of diaryl carbonates as described subsequently. It should be understood, however, that alkylaryl carbonates prepared as described herein can be used for other purposes, for example as a solvent or in the preparation of other compounds or polymers. In the preparation of diaryl carbonates, such as DPC, the alkylaryl carbonate product stream (4) is fed to a diaryl carbonate reactor (280, 380), for example a reactive distillation column as shown, To produce the product diaryl carbonate (e. G. Diphenyl carbonate). The diaryl carbonate reactor 280, 380 may be operated under conditions effective to further propel the reaction towards the desired diaryl carbonate product while separating other materials from the product (which may be used for recycle).

The alkanol product stream 10 comprises a dialkyl carbonate and an azeotrope of essentially all of the alkanols in the alkanol produced in the process, as well as minor or greater amounts of aromatic alcohols as described above. The alkanol product stream 10 may be fed to a dialkyl carbonate purification unit 260, 360 wherein the alkanol is separated as the column top component (first purified alkanol stream 12) and dialkyl carbonate Is separated as the column bottom component (purified dialkyl carbonate stream 16).

Two streams can be removed from the diaryl carbonate reactor 280 and two or three streams from the diaryl carbonate reactor 380 can be removed. For example, at least three streams: the diaryl carbonate product stream 6, the aromatic alcohol product stream 28, and the second dialkyl carbonate product stream 34 may be removed from the diaryl carbonate reactor 380 . One of the streams is a diaryl carbonate product stream 6 which can be removed from the bottom of the diaryl carbonate reactor 280, 380 and is produced with the remaining catalyst, some unreacted alkyl aryl carbonate and high- (E. G. 99 wt.% Or more) diaryl carbonate in the diaryl carbonate. The diaryl carbonate product stream 6 may optionally be further distilled and purified (if further purification is desired). Furthermore, since the reaction in the above method is carried out using a halogen-free catalyst and a starting material, the dialkyl carbonate prepared in the above method can be prepared so as not to contain a halogen. For example, the dialkyl carbonate in the diaryl carbonate product stream (6) may be present in an amount of 97 wt% with a halogen content of less than 0.5 weight percent (ppm) or less than 0.1 ppm (weight) or less than 1 weight percent (ppb) Or 99 wt% or 99.9 wt% or more.

The dialkyl carbonate product streams 26 and 34 can be removed from the top of the diaryl carbonate reactor 280 and 380 respectively and consist essentially of all (eg, 99 wt% or more) unreacted aromatic alcohol starting material, Dialkyl carbonates and some by-products alkyl aryl ethers. In one embodiment, the dialkyl carbonate product stream (26, 34) is recycled individually or in combination with the first aromatic alcohol feed stream (24) to the alkyl aryl carbonate reactor (240, 340).

The diaryl carbonate reactor (280, 380) can be operated at a temperature above 90 ° C, specifically above 100 ° C, more specifically above 110 ° C. Examples of the temperature range include 100 占 폚 to 140 占 폚, specifically 120 占 폚 to 250 占 폚, and 110 占 폚 to 240 占 폚. The operating pressure in columns 280 and 380 is greater than or equal to 10 mbar (g) (1 kPa (g)), specifically greater than 50 mbar (g) (5 kPa (g) 10 kPa (g)). Examples of pressure ranges are from 50 mbar to 3 bar g, from 5 mbar to 1 bar g and from 5 mbar to 100 bar, (g) to 900 mbar (g) (20 to 90 kPa (g)).

Both the first dialkyl carbonate product stream 2 from the dialkyl carbonate reactors 210 and 310 and the alkanol product stream 10 from the alkyl aryl carbonate reactors 240 and 340 are fed to the same purification unit, To the carbonate purification unit 260, 360, which separates the dialkyl carbonate and the alkanol to produce a first purified alkanol stream 12 and a purified dialkyl carbonate 16.

In one embodiment, the dialkyl carbonate purification unit 260, 360 is a continuous multi-stage distillation column comprising a stripping section and an enrichment section. The continuous multi-stage distillation column may include a tray or packing as the inner structure (i.e., the portion in the distillation column where the gas and liquid are actually brought into contact with each other) in each of the stripping section and the enrichment section. Examples of trays include bubble-cap trays, sieve trays, ripple trays, ballast trays, valve trays, countercurrent trays, Unifrax trays, Superfrac trays, Maxfrac trays, A double flow tray, a grid plate tray, a turbogrid plate tray, a Kittel tray, and the like. Examples of packings are random packing, such as Raschig ring, Lessing ring, Pall ring, Berl saddle, Intalox saddle, Dixon packing, McMahon packing or Heli-Pak or structured packings such as Mellapak, Gempak, Techno-pack, Flexipac, Sulzer Sulzer packing, Goodroll packing or grilling the Glitschgrid. A multi-stage distillation column having both a tray portion and a packed portion may also be used. The internal structure in both the stripping section and the enrichment section of the continuous multi-stage distillation column may be a tray. Each body portion and down Commodore (downcomer) sieve tray, for example, per square meter of 150 to 1200 holes (hole) in the body portion having a portion (hole / m ^2), or the body portion 200 to 1100 holes / m ^2, Or a sieve tray having 250 to 1000 holes / m < ² > may be used, wherein the cross sectional area per hole of each sieve tray is 0.5 to 5 square centimeters (cm ² ), or 0.7 to 4 cm ² , or 0.9 to 3 cm ² .

Effective conditions for operation of the continuous multi-stage distillation column include the type of internal structure in the distillation column and the number of stages, the type, composition and amount of the feed stream (2) and alkanol product stream (10) The purity of the obtained dialkyl carbonate, and the like. For example, the column bottom temperature may be 150 to 250 占 폚, or 170 to 230 占 폚, or 180 to 220 占 폚. The column bottom pressure is dependent on the composition in the column and the column bottom temperature used, but the continuous multi-stage distillation column dialkyl carbonate purification unit 260, 360 is typically operated at an applied pressure, for example under 1 bar to 15 bar . The reflux ratio for the continuous multi-stage distillation column may be from 0.5 to 5, or from 0.8 to 3, or from 1 to 2.5.

If the first dialkyl carbonate product stream (2) and the alkanol product stream (10) are fed to the dialkyl carbonate purification unit (260,360), the streams may be fed individually or in combination prior to entry into the column . Any feed stream may be fed in gaseous form or in liquid form. In one embodiment, the feed (s) are heated or cooled to a temperature close to the liquid temperature near the feed inlet of the dialkyl carbonate purge units 260, 360, e.g., 1 to 10 占 폚. The location at which the feed (s) are introduced into the column may be between the stripping section and the enriching section. The alkyl aryl carbonate reactor 240, 340 may have a reboiler and reflux device to heat the distillate.

The concentration of alkanol in the first purified alkanol stream 12 exiting the dialkyl carbonate purification unit 260, 360 is greater than or equal to 80 wt% based on the total weight of the first purified alkanol stream 12, Or 85 wt% or more, or 90 wt% or more. The concentration of the dialkyl carbonate in the stream 16 exiting the dialkyl carbonate purification unit 260, 360 can be 97 wt% or more, or 99 wt% or more, or 99.9 wt% or more. The content of unreacted alkanol in stream 16 may be up to 3 wt%, or up to 1 wt%, or up to 0.1 wt%.

Figure 3 illustrates that the purified dialkyl carbonate stream 16 of the dialkyl carbonate purifier unit 360 can be fed to the diaryl carbonate reactor 380. The purified dialkyl carbonate stream 16 may be liquid or vapor depending on the type of reboiler used. For example, if an external reboiler, e. G. Kettle reboiler, is used, the purified dialkyl carbonate stream 16 may be fed to the diaryl carbonate reactor 380 as a vapor. The concentration of the dialkyl carbonate in the purified dialkyl carbonate stream 16 exiting the dialkyl carbonate purification unit 360 may be at least 50 wt%, or at least 60 wt%, or at least 70 wt%. The content of unreacted alkanol in the stream 16 exiting the dialkyl carbonate purification unit 360 may be up to 50 wt%, or up to 40 wt%, or up to 30 wt%.

The diaryl carbonate product stream (6) may be removed from the bottom of the diaryl carbonate reactor (280, 380). As noted above, the diaryl carbonate product stream 6 may comprise essentially all diaryl carbonates among the diaryl carbonates prepared with the residual catalyst, unreacted alkyl aryl carbonate and high-boiling by-products. The diaryl carbonate product stream 6 may optionally be further distilled and purified (if further purification is desired).

The second dialkyl carbonate product stream 34 can be removed from the top of the diaryl carbonate reactor 380 and can include dialkyl carbonate and some byproduct alkyl aryl ethers, such as anisole. The second dialkyl carbonate product stream 34 can be recycled individually or in combination with the first aromatic alcohol feed stream 24 to the alkyl aryl carbonate reactor 340. The first aromatic alcohol feed stream 24 may comprise an alkyl aryl ether and may be recycled to the bottom inlet of the alkyl aryl carbonate reactor 340 separated from the aromatic alcohol inlet (first aromatic alcohol feed stream 24) .

All or a portion of the aromatic alcohol product stream 28 may be directed to one or both of the dialkyl carbonate purification unit 360 and the alkyl aryl carbonate reactor 340. For example, an aromatic alcohol product stream 28 of 0 to 100 wt%, specifically 50 to 100 wt%, more specifically 80 to 100 wt%, may be passed through the dialkyl carbonate purification unit 360 ). The aromatic alcohol product stream 28 from 0 to 100 wt%, specifically from 0 to 50 wt%, and more specifically from 20 to 50 wt%, can be directed to the alkyl aryl carbonate reactor 340 as the second partial stream 32 . The second partial stream 32 may be added directly to the alkylaryl carbonate reactor 340 or may be combined with the first aromatic alcohol feed stream 24 prior to entering the alkyl aryl carbonate reactor 340, It is noted that the first partial stream 30 may be added directly to the dialkyl carbonate purification unit 360 or may be combined with one or more input streams prior to entering the dialkyl carbonate purification unit 360. For example, an aromatic alcohol may be added as the second aromatic alcohol feed stream 38. When the dialkyl carbonate purification unit 360 is an extractive distillation column, the aromatic alcohol fed from the stream 30 to the dialkyl carbonate purification unit 360 acts as a solvent to extract the dialkyl carbonate when it travels through the column . Stream 30 may be fed into the top of the dialkyl purification column, where the aromatic alcohol may flow down the column and be collected from the bottom with the extracted dialkyl carbonate.

One or both of the first aromatic alcohol feed stream 24 and the second aromatic alcohol feed stream 38 may comprise recovered aromatic alcohols recovered from the molten polycarbonate polymer. The molten polymerisation system may comprise first and second oligomerization vessels, and first and second polymerization vessels, all present in series with one another. The recovered aromatic alcohol prepared in the first oligomerization vessel may comprise not less than 99.7 wt%, in particular 99.9 wt% or more, of aromatic alcohol, based on the total weight of recovered aromatic alcohols. The recovered aromatic alcohol may be produced in one or more of a second oligomerization vessel, a first polymerization vessel and a second polymerization vessel and may comprise 99.7 wt%, based on the total weight of the purified aromatic alcohol, It is possible to produce a purified recovered aromatic alcohol containing an aromatic alcohol.

One or both of the polycarbonate polymerization vessel and the new aromatic alcohol not from the recovered aromatic alcohol may be added to one or both of the first aromatic alcohol feed stream 24 and the second aromatic alcohol feed stream 38 . The new aromatic alcohol may be added in an amount of less than 1,000 kilograms per hour (kg / hr), specifically less than 500 kg / hr, more specifically less than 350 kg / hr. The recovered aromatic alcohol may be added in an amount of 1 to 40 tons (hour / hr) (t / hr), specifically 10 to 30 t / hr, more specifically 10 to 20 t / hr.

The purification system for the production of the alkyl aryl carbonate may comprise a dialkyl carbonate reactor 310, an alkyl aryl carbonate reactor 340, a dialkyl carbonate purification unit 360 and a diaryl carbonate reactor 380. The dialkyl carbonate reactor 310 may include an alkanol inlet, an alkylene carbonate inlet, an alkylene diol outlet, and a first alkanol / dialkyl carbonate outlet. The first alkanol / dialkyl carbonate outlet may be in fluid communication with the inlet of the dialkyl carbonate purification unit 360. The dialkyl carbonate purification unit 360 may comprise a dialkyl carbonate inlet, a first purified alkanol outlet, and a purified dialkyl carbonate outlet.

The diaryl carbonate reactor 380 may include a purified dialkyl carbonate inlet, an alkyl aryl ether / dialkyl carbonate outlet, an aromatic alcohol outlet, and a diaryl outlet. The purified dialkyl carbonate inlet can be in fluid communication with the purified dialkyl carbonate outlet. The alkyl aryl ether / dialkyl carbonate outlet may be in fluid communication with the inlet of the alkyl aryl carbonate reactor 340. The aromatic alcohol outlet may be in fluid communication with the inlet of the dialkyl carbonate purification unit 360 and / or the aromatic alcohol inlet of the alkyl aryl carbonate reactor 340.

The alkyl aryl carbonate reactor 340 may include an aromatic alcohol inlet, an alkyl aryl ether / dialkyl carbonate inlet, a second alkanol / dialkyl carbonate outlet, and an alkyl aryl carbonate outlet. The alkyl aryl ether / dialkyl carbonate inlet may be in fluid communication with the alkyl aryl ether / dialkyl carbonate outlet of the diaryl carbonate reactor 380. The second alkanol / dialkyl carbonate outlet may be in fluid communication with the inlet of the dialkyl carbonate purification unit 360. The alkyl aryl carbonate outlet may be in fluid communication with the inlet of the diaryl carbonate reactor 380. The aromatic alcohol outlet may be in fluid communication with the inlet of the alkyl aryl carbonate reactor 340. The purified alkanol outlet may be in fluid communication with the inlet of the dialkyl carbonate reactor 310.

The methods and processes described above can be used to prepare diaryl carbonates and diaryl carbonates from alkylene carbonates, alkanol and aromatic alcohol starting materials.

Examples of alkylene carbonates include ethylene carbonate, propylene carbonate, 1,3-dioxycyclohex-2-one, 1,3-dioxacyclohept-2-one and combinations comprising at least one of the foregoing. Ethylene carbonate or propylene carbonate may be particularly advantageous due to the ease of procurement, and ethylene carbonate is preferred.

The alkanols which may be used include all isomers of linear and branched C _1-12 aliphatic alcohols and C _4-8 cycloaliphatic alcohols, each of which is unsubstituted or substituted by 1 to 3 halogens, C _1-6 alkoxy, Cyano, C _1-6 alkoxycarbonyl, C _6-12 aryloxycarbonyl, C _1-6 acyloxy or nitro group, provided that the valency of any substituted carbon is not exceeded. Examples of the alkanol include methanol, ethanol, 1-propanol, 2-propanol, allyl alcohol, 1-butanol, 2-butanol, Cyclohexanol, cycloheptanol, cyclohexanol, 3-methylcyclopentanol, 3-ethylcycloheptanol, 2-heptanol, But are not limited to, cyclopentanol, 3-methylcyclohexanol, 2-ethylcyclohexanol (isomer), 2,3-dimethylcyclohexanol, 1,3-diethylcyclohexanol, 2-phenethyl alcohol, and 3-phenyl propanol. In a specific embodiment, the alkanol is methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol or 3-butanol. Although ethanol or methanol may be used, methanol is preferred.

The ratio between the amounts of alkylene carbonate and alkanol will depend on the type and amount of the transesterification catalyst and the reaction conditions. In order to increase the conversion of the alkylene carbonate, the alkanol is used in excess of at least twice the number of moles of alkylene carbonate, for example, the molar ratio of alkanol to alkylene carbonate is from 2 to 20, , More specifically from 5 to 12. Catalysts for ester exchange are known and include, for example.

The transesterification can be carried out in the presence of a homogeneous or heterogeneous catalyst. Examples of catalysts include alkali metals and alkaline earth metals such as lithium, sodium, potassium, magnesium, calcium and barium; Basic compounds of alkali metals and alkaline earth metals, such as hydrides, hydroxides, alkoxides, aryl oxides and amides; Basic compounds of alkali metals and alkaline earth metals such as carbonates, bicarbonates, and organic acid salts; Tertiary amines such as triethylamine, tributylamine, trihexylamine and benzyldiethylamine; Nitrogen-containing heteroaromatic compounds such as N-alkyl pyrrole, N-alkyl indole, oxazole, N-alkyl imidazole, N-alkyl pyrazole, oxadiazole, pyridine, quinoline, isoquinoline, acridine, Pyridine, pyrazine, and triazine; Cyclic amidines such as diazobicycloundecene (DBU) and diazobicyclononene (DBN); Tin compounds such as tributylmethoxy tin, dibutyl diethoxy tin, dibutyl phenoxy tin, diphenyl methoxy tin, dibutyl tin acetate, tributyl tin chloride and tin 2-ethyl hexanoate; Zinc compounds such as dimethoxy zinc, diethoxy zinc, ethylene dioxy zinc and dibutoxy zinc; Aluminum compounds such as aluminum trimethoxide, aluminum triisopropoxide and aluminum tributoxide; Titanium compounds such as tetramethoxy titanium, tetraethoxy titanium, tetrabutoxy titanium, dichlorodimethoxy titanium, tetraisopropoxy titanium, titanium acetate and titanium acetylacetonate; Phosphorus compounds such as trimethylphosphine, triethylphosphine, tributylphosphine, triphenylphosphine, tributylmethylphosphonium halide, trioctylbutylphosphonium halide and triphenylmethylphosphonium halide; Zirconium compounds such as zirconium halide, zirconium acetylacetonate, zirconium alkoxide and zirconium acetate; And lead and lead-containing compounds such as lead oxides such as PbO, PbO ₂ and Pb ₃ O ₄ , lead sulfides such as PbS, Pb ₂ S ₃ and PbS ₂ , and lead hydroxides such as Pb OH) ₂ , Pb ₃ O ₂ (OH) ₂ , Pb ₂ [PbO ₂ (OH) ₂ ] and Pb ₂ O (OH) ₂ . Specifically, the catalysts mentioned include at least one of titanium compounds such as titanium tetraphenoxide, titanium isopropylate, titanium tetrachloride, organotin compounds, and compounds of copper, lead, zinc, iron and zirconium, Combinations. The amount of catalyst used may be from 0.005 to 20 wt%, specifically from 0.01 to 10 wt%, based on the total weight of the alkylene carbonate and the alkanol.

Aromatic alcohols for the transesterification of alkyl aryl carbonates include C _6-12 aromatic alcohols which are unsubstituted or substituted with one to three halogen, C _1-6 alkoxy, cyano, C _1-6 alkoxycarbonyl, C _6-12 aryloxycarbonyl, C _1-6 acyloxy or nitro group with the proviso that the valency of any substituted carbon is not exceeded. Examples are phenol o-, m- or p-cresol, o-, m- or p-chlorophenol, o-, m- or p-methoxyphenol, 2,6- dimethylphenol, 2,4- Dimethylphenol, 1-naphthol and 2-naphthol. Specifically, phenol may be mentioned. The catalyst used for such transesterification includes those described above in the method for producing the dialkyl carbonate. Specifically, the catalysts referred to include titanium compounds such as titanium tetraphenoxide, titanium isopropylate, titanium tetrachloride, organotin compounds, and compounds of copper, lead, zinc, iron and zirconium, Combinations.

In one embodiment, the alkylene carbonate is ethylene carbonate or propylene carbonate, the alkanol is methanol or ethanol, and the aromatic alcohol is phenol. The alkyl aryl ether may be methoxybenzene.

The diaryl carbonate produced can be used for the production of polycarbonate. In one embodiment, the dihydroxy compound can be used as a reactant with a diaryl carbonate, such as diphenol carbonate, as a carbonate source.

Generally, in the melt polymerization process, the polycarbonate can be prepared by co-reacting the dihydroxy reactant and the diaryl carbonate in the molten state in the presence of an ester exchange catalyst. The reaction may be carried out in a conventional polymerization equipment such as a continuous stirred reactor (CSTR), a plug flow reactor, a wire wetting fall polymerizer, a free fall polymerizer, a wiped film polymerizer, A BANBURY mixer, a uniaxial or twin screw extruder, or a combination of the foregoing. The volatile monohydric phenol is removed from the molten reactant by distillation, and the polymer is isolated as a molten residue. The melt polymerization may be carried out as a batch process or as a continuous process. In either case, the molten polymerization conditions used may include two or more separate reaction steps, for example a first reaction step in which the starting dihydroxyaromatic compound and diaryl carbonate are converted to oligomeric polycarbonate, and a second reaction step in which the oligomer And a second reaction step in which the polycarbonate is converted to a high molecular weight polycarbonate. Such "staged" polymerization reaction conditions are particularly suitable for use in continuous polymerization systems, wherein the starting monomers are oligomerized in a first reaction vessel, and the oligomeric polycarbonate formed therein is continuously delivered to one or more downstream reactors, Wherein the oligomeric polycarbonate is converted to a high molecular weight polycarbonate. Typically, in the oligomerization step, the oligomeric polycarbonate produced has a number average molecular weight of 1,000 to 7,500 Daltons. In one or more subsequent polymerization stages, the number average molecular weight (Mn) of the polycarbonate is increased to 8,000 to 25,000 daltons (using a polycarbonate standard). Typically, no solvent is used in the process, and the reactants dihydroxyaromatic compound and diaryl carbonate are in a molten state. The reaction temperature may be 100 ° C to 350 ° C, specifically 180 ° C to 310 ° C. The pressure can be atmospheric, supra-atmospheric pressure, or an atmospheric pressure to an initial pressure of 15 torr in the initial stage of the reaction, and may be a reduced pressure, such as 0.2 to 15 torr, at a later stage. The reaction time is generally from 0.1 hour to 10 hours.

The transesterification catalyst (s) can be used in the polycarbonate polymerization. The transesterification catalyst may comprise an alkali catalyst and a quaternary catalyst. The quaternary catalyst comprises one or both of a quaternary ammonium compound and a quaternary phosphonium compound. The alkali catalyst comprises a source of one or both of an alkali ion and an alkaline earth metal ion.

Alkylaryl carbonates, diaryl carbonates, methods for making polycarbonates, as well as some embodiments of apparatus for use in the method are presented below.

Embodiment 1: As a method for producing an alkyl aryl carbonate, an alkylene carbonate and an alkanol are reacted in a dialkyl carbonate reactor in the presence of a first transesterification catalyst to obtain a first diol containing a dialkyl carbonate and an unreacted alkanol Producing an alkylene glycol product stream comprising an alkyl carbonate product stream and an alkylene glycol and an unreacted alkanol; Purifying the first dialkyl carbonate product stream in a dialkyl carbonate purification unit to provide a purified dialkyl carbonate stream and a first purified alkanol stream; Reacting the purified dialkyl carbonate stream in a diaryl carbonate reactor in the presence of a second ester exchange catalyst to produce a diaryl carbonate product stream comprising a diaryl carbonate product by disproportionation, and (i) An aromatic alcohol product stream, a second dialkyl carbonate product stream comprising said dialkyl carbonate and alkyl aryl ether, or (ii) a second dialkyl carbonate product stream comprising said dialkyl carbonate, an aromatic alcohol product and an alkyl aryl ether Separating the aromatic alcohol product from the second dialkyl carbonate product stream to produce an aromatic alcohol product stream comprising the aromatic alcohol product; (X wt%) as the first partial stream of the aromatic alcohol product stream to the dialkyl carbonate purification unit and adding a predetermined amount (100 wt% -X wt%) of the aromatic alcohol product stream as the second partial stream, To an alkyl aryl carbonate reactor wherein X wt% is greater than 0; Reacting the second dialkyl carbonate product stream, the second partial stream and the first aromatic alcohol feed stream in an alkylaryl carbonate reactor in the presence of a second transesterification catalyst to produce an alkanol product and an unreacted dialkyl carbonate, Producing an alkylaryl carbonate product stream comprising an alkanol product stream, and an alkyl aryl carbonate product and an unreacted aromatic alcohol; And purifying the alkanol product stream and the first partial stream in the dialkyl carbonate purification unit to provide the purified dialkyl carbonate stream and the first purified alkanol stream; Wherein the purifying step comprises extracting the dialkyl carbonate with the aromatic alcohol.

Embodiment 2: In Embodiment 1, at least a portion of the first purified alkanol stream is directed to the alkylaryl carbonate reactor, the dialkyl carbonate reactor, or both the alkylaryl carbonate reactor and the dialkyl carbonate reactor ≪ / RTI >

Embodiment 3: The method of embodiment 1 or 2 further comprising purifying the alkylene glycol product stream in an alkylene glycol purification unit to provide a purified alkylene glycol stream and a second purified alkanol stream Way.

Embodiment 4: The method of embodiment 3 further comprising recycling the second purified alkanol stream to the dialkyl carbonate reactor.

Embodiment 5: A method as in any one of embodiments 1-4 further comprising removing the aromatic alcohol product stream from the intermediate stage of the diaryl carbonate reactor.

Embodiment 6 In any one of embodiments 1-5, the dialkyl carbonate purification unit is an extractive distillation column, optionally wherein the distillation column has a temperature of 63 to 250 < 0 > C and 100 to 300 kPa (g) Wherein the pressure is maintained at a pressure at the top of the column.

Embodiment 7: In any one of embodiments 1-6, wherein the combination comprising the dialkyl carbonate reactor, the alkylaryl carbonate reactor, the diaryl carbonate reactor, or a combination comprising at least one of the foregoing is a reactive distillation column; Or the dialkyl carbonate reactor, the alkylaryl carbonate reactor and the diaryl carbonate reactor are reactive distillation columns.

Embodiment 8: In any one of embodiments 1-7, wherein the dialkyl carbonate reactor is operated at a temperature of 65 [deg.] C to 150 [deg.] C and a pressure at the top of the first reactive distillation column of 50 to 300 kPa (g) Wherein the alkylaryl carbonate reactor is maintained at a temperature of 120 ° C to 270 ° C and a pressure at the top of the second reactive distillation column of 200 to 700 kPa (g), wherein the first reactive distillation column Column. ≪ / RTI >

Embodiment 9: A method for producing an alkyl aryl carbonate, comprising: reacting an alkylene carbonate and an alkanol in a dialkyl carbonate reactive distillation column in the presence of a first ester exchange catalyst to prepare a dialkyl carbonate and an unreacted alkanol ; Recovering from the dialkyl carbonate reactor a first dialkyl carbonate product stream comprising the dialkyl carbonate and the unreacted alkanol and an alkylene glycol and an alkylene glycol product stream comprising the alkanol, Wherein the alkyl carbonate reactor comprises a reactive distillation column; Purifying the first dialkyl carbonate product stream in a dialkyl purification unit to provide a purified dialkyl carbonate stream and a first purified alkanol stream; Reacting the purified dialkyl carbonate stream in a diaryl carbonate reactor in the presence of a second transesterification catalyst to produce an alkyl aryl carbonate, an aromatic alcohol, an alkyl aryl ether, and an unreacted dialkyl carbonate, wherein the diaryl carbonate reactor Comprises a diaryl carbonate reactive distillation column; From the diaryl carbonate reactor a second dialkyl carbonate product stream comprising the unreacted dialkyl carbonate and the alkyl aryl ether, a diaryl carbonate product stream comprising a diaryl carbonate, and an aromatic alcohol product comprising the aromatic alcohol Recovering the stream; Directing from 0 to 100 wt% of the aromatic alcohol product stream as the first fraction stream to the dialkyl carbonate purification unit and from 0 to 100 wt% of the aromatic alcohol product stream as the second fraction stream to the alkylaryl carbonate reactor ; The second dialkyl carbonate product stream, the second partial stream and the first aromatic alcohol feed stream are reacted in an alkylaryl carbonate reactor in the presence of a second transesterification catalyst to form an alkylaryl carbonate, an alkanol and an unreacted dialkyl carbonate Wherein the alkylaryl carbonate reactor comprises a reactive distillation column; Recovering from the alkyl aryl carbonate reactor an alkanol product stream comprising the alkanol and the unreacted dialkyl carbonate, and an alkyl aryl carbonate product stream comprising the alkyl aryl carbonate; And purifying the alkanol product stream in the dialkyl carbonate purification unit to provide the purified dialkyl carbonate stream and the first purified alkanol stream.

Embodiment 10: The method of embodiment 9, comprising recycling the first purified alkanol stream to the alkylaryl carbonate reactor; Recycling the first purified alkanol stream to the dialkyl carbonate reactor; Purifying the purified alkylene glycol stream in an alkylene glycol purification unit to provide a purified alkane diol stream and a second purified alkanol stream and recycling the second purified alkanol stream to the alkylene glycol purification unit step; And recycling the second partial stream to the bottom of the alkylaryl carbonate reactor.

Embodiment 11: A method as in any one of embodiments 1-10 further comprising reacting the alkylaryl carbonate product stream in the diaryl carbonate reactor.

Embodiment 12: A method according to any one of Embodiments 1 to 11, further comprising the step of polymerizing an aromatic dihydroxy compound and the diaryl carbonate in the presence of a catalyst to prepare a polycarbonate.

Embodiment 13: In any one of embodiments 1-12, the alkylene carbonate comprises a combination comprising ethylene carbonate, propylene carbonate, or one or both of the foregoing, wherein the alkanol is selected from the group consisting of methanol, ethanol , Or a combination comprising one or both of the foregoing, wherein the dialkyl carbonate comprises a combination comprising dimethyl carbonate, diethyl carbonate, or one or both of the foregoing, wherein the aromatic alcohol comprises phenol And wherein the alkyl aryl carbonate comprises methyl phenyl carbonate, ethyl phenyl carbonate, or a combination comprising one or both of the foregoing.

Embodiment 14: In any one of embodiments 1-13, the method further comprises adding the recovered aromatic alcohol to either or both of the first aromatic alcohol feed stream and the second aromatic alcohol feed stream Wherein the recovered aromatic alcohol is recovered from the molten polycarbonate polymer and comprises at least 99.7 wt% of aromatic alcohol based on the total weight of the recovered aromatic alcohol and wherein the recovered aromatic alcohol is a second oligomer Wherein the method further comprises purifying the recovered aromatic alcohol prior to the addition step when recovered from at least one of the polymerization vessel, the first polymerization vessel and the second polymerization vessel.

Embodiment 15: In any one of embodiments 1-14, the diaryl carbonate product comprises a metal compound, the metal compound comprises molybdenum of up to 500 ppb; Vanadium below 33 ppb; Chromium of 33 ppb or less; 75 ppb or less of titanium; Niobium of less than 375 ppb; Nickel of 33 ppb or less; 10 ppb or less zirconium; And 10 ppb or less of iron (all based on the total weight of the diaryl carbonate product and the metal compound).

Embodiment 16: The method of any one of embodiments 1-15, wherein X is 20 wt% or more, specifically 50 wt% or more, more specifically 90 wt% or more.

Embodiment 17: A system for the production of an alkyl aryl carbonate comprising a dialkyl carbonate reactor, an alkylaryl carbonate reactor, a dialkyl carbonate purification unit and a diaryl carbonate reactor; Wherein the dialkyl carbonate reactor comprises a first alkanol / dialkyl carbonate outlet in fluid communication with an alkanol inlet, an alkylene carbonate inlet, an alkylene diol outlet, and a dialkyl carbonate inlet of the dialkyl carbonate purification unit; The dialkyl carbonate purification unit comprises the dialkyl carbonate inlet, a first purified alkanol outlet, a purified dialkyl carbonate outlet; And a unit aromatic alcohol inlet; The diaryl carbonate reactor having a purified dialkyl carbonate inlet in fluid communication with the purified dialkyl carbonate outlet, an alkyl aryl ether / dialkyl carbonate outlet in fluid communication with the alkyl aryl ether / dialkyl carbonate inlet of the alkyl aryl carbonate reactor An aromatic alcohol inlet port in fluid communication with the unit aromatic alcohol inlet of said dialkyl carbonate purifying unit and optionally with an aromatic alcohol inlet of the reactor of said alkylaryl carbonate reactor, and a diaryl outlet; Wherein the alkylaryl carbonate reactor comprises an alkylaryl ether / dialkyl carbonate inlet in fluid communication with the reactor aromatic alcohol inlet, an alkylaryl ether / dialkyl carbonate outlet of the diaryl carbonate reactor, an alkanol / alkylaryl carbonate inlet of the dialkyl carbonate purification unit, A second alkanol / dialkyl carbonate outlet in fluid communication with the dialkyl carbonate inlet, and an alkyl aryl carbonate outlet.

Embodiment 18: The system of embodiment 17 wherein said aromatic alcohol outlet is in fluid communication with said reactor aromatic alcohol inlet.

Embodiment 19: A system for the production of an alkyl aryl carbonate, comprising: a dialkyl carbonate reactor, an alkylaryl carbonate reactor, a dialkyl carbonate purification unit, a diaryl carbonate reactor; And an aromatic alcohol separation unit; Wherein the dialkyl carbonate reactor comprises a first alkanol / dialkyl carbonate outlet in fluid communication with an alkanol inlet, an alkylene carbonate inlet, an alkylene diol outlet, and a dialkyl carbonate inlet of the dialkyl carbonate purification unit; The dialkyl carbonate purification unit comprises the dialkyl carbonate inlet, a first purified alkanol outlet, a purified dialkyl carbonate outlet; And a unit aromatic alcohol inlet; The diaryl carbonate reactor having a purified dialkyl carbonate inlet in fluid communication with the purified dialkyl carbonate outlet, an aromatic alcohol separation unit wherein the aromatic alcohol separation unit comprises an aromatic outlet in fluid communication with the unit aromatic alcohol inlet, An alkylaryl ether / dialkyl carbonate outlet in fluid communication with a separation inlet of the alkylaryl ether / dialkyl carbonate outlet in fluid communication with the alcohol inlet, and a diaryl outlet; Wherein the alkylaryl carbonate reactor comprises an alkylaryl carbonate reactor comprising a reactor aromatic alcohol inlet, a second alkanol / dialkyl carbonate outlet in fluid communication with the alkanol / dialkyl carbonate inlet of the dialkyl carbonate purification unit, A system for the production of aryl carbonates.

[0062] Embodiment 20: The system of embodiments 17-19, wherein the alkylaryl carbonate outlet is in fluid communication with an alkylaryl carbonate inlet of the diaryl carbonate reactor.

[0216] Embodiment 21: The system as in any one of embodiments 17-20, wherein the purified alkanol outlet is in fluid communication with an alkanol inlet of the dialkyl carbonate reactor.

In general, this embodiment may alternatively comprise (e.g., include), consist of, or consist essentially of any suitable ingredient disclosed herein. This embodiment may additionally or alternatively be used with compositions of the prior art or without any components, materials, components, adjuvants or paper that are not otherwise required to achieve the functions and / or purposes of the present embodiments, By weight.

The trace amount used herein is an amount of less than 0.01 wt% based on the total weight of the product. (For example, a range of "up to 25 wt% or more specifically from 5 wt% to 20 wt%" includes each end point), and the endpoints include independently endpoints , "5 wt% to 25 wt% ", and the like). "Combination" includes blends, mixtures, alloys, reaction products, and the like. Also, the terms "first "," second ", etc. used herein are used to distinguish one element from another, rather than indicating any order, quantity, or importance. The singular forms of the term and "above" are not to be construed as limiting the quantity, and should be construed to include both singular and plural unless otherwise stated or contradicted by context. "Or" means "and / or" unless expressly stated otherwise. As used herein, the suffix "(s)" is intended to include both the singular and the plural of the term modifying it, and accordingly includes at least one of the terms (e.g., . Reference throughout this specification to "one embodiment "," another embodiment ", "an embodiment ", etc., means that a particular element (e.g., feature, structure and / or characteristic) Quot; is included in at least one embodiment described herein and may or may not be present in other embodiments. It is also to be understood that the described elements may be combined in any suitable manner in various implementations.

Although specific implementations have been described, alternatives, modifications, changes, enhancements, and substantial equivalents that may or may not be presently anticipated may come to mind to the applicant or other ordinarily skilled artisan. Accordingly, it is intended that the appended claims, which may be both submitted and amended, include all such alternatives, modifications, variations, improvements and substantial equivalents.

Claims (20)

A method for preparing an alkyl aryl carbonate,
Alkylene carbonate and an alkanol in a dialkyl carbonate reactor in the presence of a first ester exchange catalyst to form a first dialkyl carbonate product stream comprising a dialkyl carbonate and an unreacted alkanol and a first dialkyl carbonate product stream comprising an alkylene glycol and an unreacted alkanol ≪ / RTI > to produce an alkylene glycol product stream;
Purifying the first dialkyl carbonate product stream in a dialkyl carbonate purification unit to provide a purified dialkyl carbonate stream and a first purified alkanol stream;
Reacting the purified dialkyl carbonate stream in a diaryl carbonate reactor in the presence of a second ester exchange catalyst to produce a diaryl carbonate product stream comprising a diaryl carbonate product by disproportionation, and (i) An aromatic alcohol product stream, a second dialkyl carbonate product stream comprising said dialkyl carbonate and alkyl aryl ether, or (ii) a second dialkyl carbonate product stream comprising said dialkyl carbonate, an aromatic alcohol product and an alkyl aryl ether Separating the aromatic alcohol product from the second dialkyl carbonate product stream to produce an aromatic alcohol product stream comprising the aromatic alcohol product;
(X wt%) as the first partial stream of the aromatic alcohol product stream to the dialkyl carbonate purification unit and adding a predetermined amount (100 wt% -X wt%) of the aromatic alcohol product stream as the second partial stream, To an alkyl aryl carbonate reactor wherein X wt% is greater than 0;
Reacting the second dialkyl carbonate product stream, the second partial stream and the first aromatic alcohol feed stream in an alkylaryl carbonate reactor in the presence of a second transesterification catalyst to produce an alkanol product and an unreacted dialkyl carbonate, Producing an alkylaryl carbonate product stream comprising an alkanol product stream, and an alkyl aryl carbonate product and an unreacted aromatic alcohol;
Purifying said alkanol product stream and said first partial stream in said dialkyl carbonate purification unit to provide said purified dialkyl carbonate stream and said first purified alkanol stream
Wherein the refining step comprises extracting the dialkyl carbonate with the aromatic alcohol. ≪ Desc / Clms Page number 19 > The method of claim 1, further comprising the step of directing at least a portion of the first purified alkanol stream to the alkylaryl carbonate reactor, the dialkyl carbonate reactor, or both the alkylaryl carbonate reactor and the dialkyl carbonate reactor ≪ / RTI > 3. The method of claim 1 or 2, further comprising purifying the alkylene glycol product stream in an alkylene glycol purification unit to provide a purified alkylene glycol stream and a second purified alkanol stream. 4. The method of claim 3, further comprising recycling the second purified alkanol stream to the dialkyl carbonate reactor. 5. The process according to any one of claims 1 to 4, comprising removing the aromatic alcohol product stream from the intermediate stage of the diaryl carbonate reactor. 6. The process according to any one of claims 1 to 5, wherein the dialkyl carbonate purification unit is an extractive distillation column. 7. The process according to any one of claims 1 to 6, wherein the combination comprising the dialkyl carbonate reactor, the alkylaryl carbonate reactor, the diaryl carbonate reactor or a combination comprising at least one of the foregoing is a reactive distillation column; Or the dialkyl carbonate reactor, the alkylaryl carbonate reactor and the diaryl carbonate reactor are reactive distillation columns. 8. A process according to any one of claims 1 to 7, wherein the dialkyl carbonate reactor is maintained at a temperature of 65 DEG C to 150 DEG C and at a pressure at the top of the first reactive distillation column of 50 to 300 kPa (g) 1 reactive distillation column wherein said alkylaryl carbonate reactor is maintained at a temperature of 120 ° C to 270 ° C and a pressure at the top of a second reactive distillation column of 200 to 700 kPa (g) How to do it. A method for preparing an alkyl aryl carbonate,
Reacting an alkylene carbonate and an alkanol in a dialkyl carbonate reactive distillation column in the presence of a first ester exchange catalyst to produce a dialkyl carbonate and an unreacted alkanol;
Recovering from the dialkyl carbonate reactor a first dialkyl carbonate product stream comprising the dialkyl carbonate and the unreacted alkanol and an alkylene glycol and an alkylene glycol product stream comprising the alkanol, Wherein the alkyl carbonate reactor comprises a reactive distillation column;
Purifying the first dialkyl carbonate product stream in a dialkyl purification unit to provide a purified dialkyl carbonate stream and a first purified alkanol stream;
Reacting the purified dialkyl carbonate stream in a diaryl carbonate reactor in the presence of a second transesterification catalyst to produce an alkyl aryl carbonate, an aromatic alcohol, an alkyl aryl ether, and an unreacted dialkyl carbonate, wherein the diaryl carbonate reactor Comprises a diaryl carbonate reactive distillation column;
From the diaryl carbonate reactor a second dialkyl carbonate product stream comprising the unreacted dialkyl carbonate and the alkyl aryl ether, a diaryl carbonate product stream comprising a diaryl carbonate, and an aromatic alcohol product comprising the aromatic alcohol Recovering the stream;
Directing from 0 to 100 wt% of the aromatic alcohol product stream as the first fraction stream to the dialkyl carbonate purification unit and from 0 to 100 wt% of the aromatic alcohol product stream as the second fraction stream to the alkylaryl carbonate reactor ;
The second dialkyl carbonate product stream, the second partial stream and the first aromatic alcohol feed stream are reacted in an alkylaryl carbonate reactor in the presence of a second transesterification catalyst to form an alkylaryl carbonate, an alkanol and an unreacted dialkyl carbonate Wherein the alkylaryl carbonate reactor comprises a reactive distillation column;
Recovering from the alkyl aryl carbonate reactor an alkanol product stream comprising the alkanol and the unreacted dialkyl carbonate, and an alkyl aryl carbonate product stream comprising the alkyl aryl carbonate; And
Purifying said alkanol product stream in said dialkyl carbonate purification unit to provide said purified dialkyl carbonate stream and said first purified alkanol stream
≪ / RTI > 10. The method of claim 9,
Recycling the first purified alkanol stream to the alkylaryl carbonate reactor;
Recycling the first purified alkanol stream to the dialkyl carbonate reactor;
Purifying the purified alkylene glycol stream in an alkylene glycol purification unit to provide a purified alkane diol stream and a second purified alkanol stream and recycling the second purified alkanol stream to the alkylene glycol purification unit step; And
Recycling the second partial stream to the bottom of the alkylaryl carbonate reactor
≪ / RTI > 11. The process according to any one of claims 1 to 10, further comprising reacting the alkylaryl carbonate product stream in the diaryl carbonate reactor. 12. The method according to any one of claims 1 to 11, further comprising the step of polymerizing the aromatic dihydroxy compound and the diaryl carbonate in the presence of a catalyst to prepare a polycarbonate. 13. The process of any one of claims 1 to 12 wherein the alkylene carbonate comprises ethylene carbonate, propylene carbonate, or a combination comprising one or both of the foregoing, wherein the alkanol is selected from the group consisting of methanol, ethanol, Or a combination comprising both, wherein the dialkyl carbonate comprises a combination comprising dimethyl carbonate, diethyl carbonate, or one or both of the foregoing, wherein the aromatic alcohol comprises phenol, Wherein the alkyl aryl carbonate comprises methyl phenyl carbonate, ethyl phenyl carbonate, or a combination comprising one or both of the foregoing. 14. The process according to any one of claims 1 to 13, wherein the process further comprises the step of adding the recovered aromatic alcohol to either or both of the first aromatic alcohol feed stream and the second aromatic alcohol feed stream Wherein the recovered aromatic alcohol is recovered from the molten polycarbonate polymer and comprises at least 99.7 wt% of aromatic alcohol based on the total weight of the recovered aromatic alcohol and the recovered aromatic alcohol is recovered from the second oligomerization vessel, Wherein the method further comprises purifying the recovered aromatic alcohol prior to the addition step when recovered from at least one of the first polymerization vessel and the second polymerization vessel. 15. The process according to any one of claims 1 to 14, wherein the diaryl carbonate product comprises a metal compound, the metal compound is molybdenum of up to 500 ppb; Vanadium below 33 ppb; Chromium of 33 ppb or less; 75 ppb or less of titanium; Niobium of less than 375 ppb; Nickel of 33 ppb or less; 10 ppb or less zirconium; And 10 ppb or less of iron (all based on the total weight of the diaryl carbonate product and the metal compound). A system for the production of an alkyl aryl carbonate,
A dialkyl carbonate reactor, an alkylaryl carbonate reactor, a dialkyl carbonate purification unit, and a diaryl carbonate reactor;
Wherein the dialkyl carbonate reactor comprises a first alkanol / dialkyl carbonate outlet in fluid communication with an alkanol inlet, an alkylene carbonate inlet, an alkylene diol outlet, and a dialkyl carbonate inlet of the dialkyl carbonate purification unit;
The dialkyl carbonate purification unit comprises the dialkyl carbonate inlet, a first purified alkanol outlet, a purified dialkyl carbonate outlet; And a unit aromatic alcohol inlet;
The diaryl carbonate reactor having a purified dialkyl carbonate inlet in fluid communication with the purified dialkyl carbonate outlet, an alkyl aryl ether / dialkyl carbonate outlet in fluid communication with the alkyl aryl ether / dialkyl carbonate inlet of the alkyl aryl carbonate reactor An aromatic alcohol inlet port in fluid communication with the unit aromatic alcohol inlet of said dialkyl carbonate purifying unit and optionally with an aromatic alcohol inlet of the reactor of said alkylaryl carbonate reactor, and a diaryl outlet;
Wherein the alkylaryl carbonate reactor comprises an alkylaryl ether / dialkyl carbonate inlet in fluid communication with the reactor aromatic alcohol inlet, an alkylaryl ether / dialkyl carbonate outlet of the diaryl carbonate reactor, an alkanol / alkylaryl carbonate inlet of the dialkyl carbonate purification unit, A second alkanol / dialkyl carbonate outlet in fluid communication with the dialkyl carbonate inlet, and an alkyl aryl carbonate outlet.
A system for the production of alkyl aryl carbonate. 17. The system of claim 16, wherein the aromatic alcohol outlet is in fluid communication with the reactor aromatic alcohol inlet. A system for the production of an alkyl aryl carbonate,
A dialkyl carbonate reactor, an alkylaryl carbonate reactor, a dialkyl carbonate purification unit, a diaryl carbonate reactor, and an aromatic alcohol separation unit;
Wherein the dialkyl carbonate reactor comprises a first alkanol / dialkyl carbonate outlet in fluid communication with an alkanol inlet, an alkylene carbonate inlet, an alkylene diol outlet, and a dialkyl carbonate inlet of the dialkyl carbonate purification unit;
The dialkyl carbonate purification unit comprises the dialkyl carbonate inlet, a first purified alkanol outlet, a purified dialkyl carbonate outlet; And a unit aromatic alcohol inlet;
The diaryl carbonate reactor having a purified dialkyl carbonate inlet in fluid communication with the purified dialkyl carbonate outlet, an aromatic alcohol separation unit wherein the aromatic alcohol separation unit comprises an aromatic outlet in fluid communication with the unit aromatic alcohol inlet, An alkylaryl ether / dialkyl carbonate outlet in fluid communication with a separation inlet of the alkylaryl ether / dialkyl carbonate outlet in fluid communication with the alcohol inlet, and a diaryl outlet;
Wherein the alkylaryl carbonate reactor comprises a reactor aromatic alcohol inlet, a second alkanol / dialkyl carbonate outlet in fluid communication with the alkanol / dialkyl carbonate inlet of the dialkyl carbonate purification unit, and an alkyl aryl carbonate outlet.
A system for the production of alkyl aryl carbonate. 19. The system of any one of claims 16 to 18, wherein the alkylaryl carbonate outlet is in fluid communication with an alkylaryl inlet of the diaryl carbonate reactor. 20. The system of any one of claims 16 to 19, wherein the purified alkanol outlet is in fluid communication with an alkanol inlet of the dialkyl carbonate reactor.

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