RU2619461C2 - Method for producing of bisphenol a - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: present invention relates to the process for producing bisphenol A by the condensation reaction of acetone and phenol in the presence of strongly acidic sulfonated ion exchange resins, which consists in the following: the reaction mixture containing acetone, phenol and reaction products of phenol with acetone is contacted with the ion exchange catalyst in at least two reactors until the total water content is 2.5 cg / g, and phenol and acetone is introduced into the reactor (1) and the post-reaction mixture is introduced from the reactor (1) mixed (2) with postcrystallizational solutions from molds ( 8), and acetone in a mixer is introduced into the reactor (3); the post-reaction mixture after the reactor (3) is mixed in a mixer (4) with part of phenol solution (no more than 40 cg/g) obtained by contacting of dewatering mixture containing not more than 1.0% of water with the ion exchange catalyst in at least one reactor (5); the post-reaction mixture from the mixer (4) is fed to the adsorber (6) at a temperature not exceeding 150°C and a flow rate of 10 m/h with a phenol solution pH stabilizer as a continuous layer with a grain size of not more than 1.2mm, comprising carboxyl and / or hydroxyl and / or amide groups, while the post-reaction mixture reaches pH of 5-6 after the adsorber (6); concentrating of the post-reaction mixture from the adsorber (6) is carried out in the fractionation column (7) by partial or complete evaporation of volatile substances such as distillate containing phenol, acetone and water, at the boiling point at normal pressure of not more than 200°C and crystallization of bisphenol A is performed from distillation residue; at least 60% of the phenol solution from the reactor (5) is fed to the adsorber (9) at a temperature of no more than 150°C and a flow rate of 10 m / h, with phenol solution pH stabilizer as a continuous layer having a grain size of not more than 1.2 mm, comprising carboxyl and / or hydroxyl and/or amide groups, until the mixture reaches pH of 5 -6 units after the adsorber (9), and the obtained solution is mixed with the distillate from the fractionation column (7), containing phenol, acetone and water, and fed to fractionation column (10); phenol separated in the column (10) is recycled to the reactor (1), acetone - to the reactor (1) and/or (3), and the aqueous fraction is removed from the apparatus as waste water.

EFFECT: invention provides obtaining of bisphenol, a with the use of pH level stabilizer of phenol solutions , thus enhancing the durability of a condensation catalyst and improving the thermal stability of the end product.

6 cl, 1 dwg, 1 ex

Description

The present invention relates to a method for producing bisphenol A used for the manufacture of plastics, primarily polycarbonates and mixtures thereof, used for the manufacture of structural elements in the automotive industry, in the manufacture of medical equipment and sports equipment, as well as in the production of consumer goods.

Moreover, bisphenol A [2,2-bis- (4-hydroxyphenyl) propane], also known as the p, p-isomer of DPP or DPP, is also used for the manufacture of epoxy resins, unsaturated polyester resins, polysulfone resins and polyetherimides, as well as additives to plastics - in particular, agents that reduce their flammability, for example, tetrabromobisphenol A and phenyl phosphate DPP and thermal stabilizers poly (vinyl chloride).

Bisphenol A can be obtained by condensation of acetone with phenol in the presence of a strongly acidic catalyst, for example, aprotic acids or Lewis acids. Currently, the preferred method of producing bisphenol A is the condensation of acetone with phenol, carried out in the presence of an ion exchange catalyst such as a sulfonated copolymer of styrene with divinylbenzene, and an additional promoter that increases the efficiency and selectivity of the reaction (thiol compounds, for example 2,2-dimethyl-1,3- thiazolidine and 2-aminoethanethiol).

The bisphenol A synthesis unit is a multi-stage system of flow reactors with a constant catalyst bed connected in series through heat exchangers to maintain a given temperature range in each reactor. Individual embodiments differ in the method of dispensing acetone and post-crystallization solutions obtained at the stage of isolation and purification of DPP.

The embodiment of such a reactor system described in US Pat. condensation.

In many embodiments, the return of post-crystallization solutions in the form of unreacted phenol and DPP, the crystallization of which did not occur before the start of the concentration stage, significantly reduces the consumption of raw materials. Another advantage resulting from the return of the mother liquor to the synthesis step is the limitation of the formation of 2- (2-hydroxyphenyl) -2- (4-hydroxyphenyl) propane (the so-called o, p-isomer of DPP), since the system in this case much closer to the state of balance between the p, p-isomer of the TPP and o, the p-isomer of the TPP. In processes in which the use of a multistage system of flow reactors with a constant layer is provided, the mother liquor can be returned in several ways, when the return occurs at the first stage of the condensation reaction or at subsequent stages of such a reaction. The greatest advantage of such a limitation on the formation of the o, p-isomer of DPP is achieved by returning the mother liquor to the first stage of synthesis, therefore, the patent literature contains mainly solutions providing that the return of a part of the mother liquor to different stages of synthesis is only a possible option without indicating the resulting advantages (US 6858759).

In the synthesis of bisphenol from phenol and acetone, the reaction of the formation of the p, p-isomer of DPP is accompanied by a number of side reactions in which the o, p-isomers of DPP, o, the o-isomers of DPP, codimers, p-isopropenylphenol, p-isopropylphenol, linear dimers, cyclic dimers, trisphenol, and many other unidentified compounds to date. By-products can accumulate in process streams, which is a well-known and widely occurring phenomenon on an industrial scale that affects product quality degradation. The essence of modern technology for the production of DPP is to control the content of by-products in the streams so that the conditions for the isolation and purification of DPP from the post-reaction mixture are as stable as possible.

A very important stage of the synthesis is the stage of separation of pure DPP from the reaction mixture.

Most often, acetone, water and a small amount of phenol are removed by vacuum distillation. The DPP phenol adduct crystallizes upon cooling of the residues. Phenol is subjected to vacuum distillation to obtain DPP from individual crystals of the adduct.

Many methods have been described for the isolation of more pure bisphenol. EP 0330146 describes a crystallization process for the adduct of bisphenol A / phenol. A method has also been patented which consists in crystallization of the crude bisphenol A obtained from the melt obtained by separation by distillation of unreacted acetone, water and phenol from the products of the condensation reaction.

WO 0035847 discloses suspension crystallization of the DPP-phenol adduct, separation of it from the mother liquor by filtration, decomposition of the adduct by vacuum distillation of phenol and fractional crystallization of the resulting crude DPP.

The available patent information sources describe different methods for purifying DFP:

- isolation of DPP in the form of an adduct of DPP-phenol from the reaction medium and purification by washing with pure phenol or a mixture of phenol with water;

- crystallization of crude DPP from organic solvents or a mixture of organic solvents;

- distillation in high vacuum.

Distillation of the post-reaction mixture formed as a result of the synthesis of DPP is carried out with the aim of removing unreacted components and water. At high temperatures, the decomposition of DPP into phenol and isopropenylphenol takes place, which in turn are subject to further reactions and increase the proportion of by-products, including non-ferrous metal complexes with phenols, resulting in intense staining of the crude DPP. A method for limiting the decomposition reaction of DPP is the neutralization of acid impurities present in the post-reaction mixture by introducing neutralizing compounds (alkali metal carbonates and hydroxides), passing the crude DPP through a cation exchange resin (Na, K, Li, Ca, Mg) or inorganic ion exchangers (US 6512148 )

Ways to reduce the formation of by-products known from the patent descriptions include, in particular, an isomerization reaction, namely the conversion of the o, p-isomer of DPP to p, the p-isomer of DPP (JP 08333290), in which the advantage is that after crystallization adduct of DPP / phenol, concentration of o, p-isomer of DPP exceeds its equilibrium content; and also the process of catalytic decomposition that occurs under the influence of acid (WO 0040531) and alkaline (PL 181992) catalysts.

Bisphenol A is an unstable compound, subject to a gradual decomposition reaction under the influence of temperature, light, in the presence of acids, alkalis and oxygen. The decomposition of the bisphenol A molecule is due to the instability of the bond of the Quaternary carbon atom with phenolic hydroxyl. The decomposition products contained in DPP even in small amounts during the synthesis of polycarbonates slow down the increase in molecular weight and worsen the mechanical and optical properties of the polymer. Many TPP contaminants are formed as a result of the decomposition reaction during heat treatment and purification of DPP.

It is possible to limit the formation of color complex compounds and increase the stability of DPP through the use of stabilizers.

Stabilizers are chemical compounds introduced into the material in small quantities (1-2%). A variety of types and structures of chemical compounds used as stabilizers, allows you to choose a stabilizer suitable for the type of material being stabilized and the intended conditions for its storage, use or processing. The addition of phosphoric acid (1) to the crude DPP before distillation purification limits the formation of non-ferrous metal complex compounds with phenol and DPP derivatives during heat treatment (EP 0816319). A noticeable stabilizing effect has the method of crystallization of DPP from phenol at a temperature of 185-220 ° C in an oxygen-free atmosphere (JP 6025045) or the introduction of additives, for example boric acid, alkyl titanates, phthalic anhydride, phosphoric acid salt (V) and (lll) with alkali metals ( CS 272518).

The aim of the invention was to develop a method for producing bisphenol A, in which the catalytic system is characterized by increased durability, and the synthesis product is characterized by increased thermal stability.

During the production of bisphenol A from phenol and acetone in a multi-stage reaction system using sulfonated ion-exchange resins as catalysts for the reaction, the presence of polycyclic by-products in postsynthetic flows affects the reaction kinetics and catalyst durability as a result of deposition on the catalyst surface and a decrease in the availability of reactants for active centers. It was unexpectedly found that the addition of a stabilizer of the pH level of phenolic solutions slows down side processes, increasing the durability of the condensation catalyst, and improves the thermal stability of the final product.

The essence of the invention is as follows:

- a reaction mixture containing acetone, phenol and phenol-acetone reaction products is contacted with an ion exchange catalyst in at least two reactors until the total water content reaches 2.5 g / g, with acetone and phenol being introduced into reactor 1, and reactor 3 introduces a post-reaction mixture from reactor 1, mixed in a mixer 2 with post-crystallization solutions from crystallizers 8, as well as with acetone;

- the post-reaction mixture after reactor 3 is mixed in mixer 4 with a part of phenol solution, not more than 40 g / g, obtained as a result of contact of the dehydration mixture containing not more than 1.0% water with an ion-exchange catalyst in at least one reactor 5;

- the post-reaction mixture from the mixer 4 is contacted in the adsorber 6 at a temperature of not more than 150 ° C with a flow velocity of not more than 10 m / h with a stabilizer of the pH level of phenol solutions having the form of a constant layer with a grain size of not more than 1.2 mm, having a carboxyl, and / or hydroxyl functional and / or amide groups until the post-reaction mixture reaches a pH of 5-6 units after adsorber 6;

- the post-reaction mixture (after adsorber 6) is concentrated in distillation column 7 by evaporation of part or all of the volatile components, such as distillate containing phenol, acetone and water, having a boiling point (at normal pressure) of not more than 200 ° C, and bisphenol A crystallizes from the residue of distillation;

- at least 60% phenol solution from the reactor 5 is contacted in the adsorber 9 at a temperature of not more than 150 ° C with a flow velocity of not more than 10 m / h with a stabilizer of the pH level of phenol solutions having the form of a constant layer with a grain size of not more than 1.2 mm containing carboxyl and / or hydroxyl and / or amide groups until the mixture reaches a pH value of 5-6 units after adsorber 9, and the resulting solution is mixed with distillate from a distillation column 7 containing phenol, acetone and water, and sent to distillation column 10;

- phenol, which is released in column 10, is returned to reactor 1, and acetone is returned to reactor 1 and / or 3, and the aqueous fraction is removed from the plant in the form of waste water.

Preferably, the dehydration mixture containing not more than 1 g / g of water is contacted in the reactor 5 with an ion exchange catalyst at a temperature of not more than 95 ° C. at a flow velocity of not more than 2.0 m / h.

Preferably, the dehydration mixture is contacted in reactors 1 and 3 with an ion exchange catalyst at a temperature of not more than 85 ° C. at a flow velocity of not more than 6 m / h.

Preferably, a reaction mixture or a dehydration mixture can be sent to each of the reactors, depending on needs.

Preferably, a pH stabilizer of a phenolic solution with a molar ratio of hydroxyl (—OH) to carboxyl (—COOH) functional groups of not more than 1: 1 is used.

Preferably, a pH stabilizer of a phenolic solution with a molar ratio of amide (-CONH ₂ ) and carboxyl (-COOH) functional groups of not more than 1: 2 is used.

Example

The schematic diagram of the DPP synthesis unit is shown in the figure.

The synthesis of bisphenol is carried out in a reaction system consisting of 3 ion-exchange reactors with a volume of 0.5 dm ³ each. The same catalyst is placed in the reactors.

The characteristics of the ion exchange catalyst used for the condensation reaction of phenol with acetone are presented in table 1.

The reaction mixture is fed into reactors 1 and 3, and a dehydration mixture is fed into reactor 5.

In the reactor 1 is continuously fed a reaction mixture consisting of acetone, water and phenol in an amount of 1.0 kg / l.

The composition of the reaction mixture at the inlet to the reactor 1 and the synthesis conditions are presented in table 2.

As a result of the condensation reaction of phenol with acetone in an acidic medium, a mixture is obtained, the composition of which is presented in table 3.

The reaction mixture from reactor 1 is mixed with post-crystallization solutions from crystallizers 8 obtained by isolating the synthesis product of the p, p-isomer of DPP through a combination of suspension and fractional crystallizations. Mixing of solutions is carried out in a mixer with a capacity of 5.0 dm ³ , equipped with an anchor mixer with a rotation speed of 120 rpm and a heating casing with temperature control in the range of 25-100 ° C. Post-crystallization solutions are mixed in a mixer 2 with the reaction solution from reactor 1 at a temperature of 72.5 ° C, after which the solution obtained by mixing the streams is cooled to a temperature of 55 ° C and 80.8 g of acetone is added to it. After thorough mixing, the mixture is dosed into the reactor 3.

The composition and number of individual solutions are presented in table 4

The solution obtained by mixing the streams is cooled to a temperature of 55 ° C and 80.8 g of acetone is added to it. After thorough mixing, the mixture is dosed into the reactor 3.

The synthesis conditions for bisphenol in reactor 3 are presented in table 5.

At the same time, in the reactor 5, the ion exchange catalyst is dehydrated. A dehydration mixture consisting of 0.3% water and 99.7% phenol is fed to reactor 5.

Table 6 presents the conditions for dehydration of the ion-exchange catalyst in the reactor 5.

The phenol solution from reactor 5 is divided into two parts in a proportion of 32% and 68%. A smaller stream of 174.7 g / h (0.174 kg / h) is mixed with the post-reaction solution from reactor 3 (2.127 kg / h). Mixing of solutions is carried out in mixer 4 with a volume of 3.0 dm ³ at a temperature of 72 ° C; it turns out 2,301 kg / h of a mixture, which is then dosed into an adsorber 6 filled with a stabilizer of the pH level of phenol solutions. In the adsorber 6 is placed 0.5 DM polymer filling with a grain size in the range of 0.2-1.1 mm with carboxylic (-COOH) and hydroxyl (-OH) functional groups.

The adsorber filling characteristic is presented in table 7.

The post-reaction mixture from reactor 3, as well as part of the phenol solution, is sent to mixer 4, and then all together is passed through a stabilizer layer in adsorber 6 at a speed of 4.2 m / h at a temperature of 72 ° C. The mixture after adsorber 6 with a pH of 5.5 is concentrated by vacuum distillation at a pressure of 21 kPa in a column 7 filled in the form of glass rings, with a ratio of distillate and irrigation 3.0: 1. In the boiler of the column, the fluid temperature is maintained at 135 ° C. As a result of vacuum distillation, the mixture after adsorber 6 is divided into two streams:

- a stream of concentrated products to isolate the p, p-isomer of DPP

- distillate

Table 8 presents the composition of the flows of concentration of solutions of the synthesis products

For the second part of the phenol solution from reactor 5 (68%, 0.372 kg / h), stabilization is performed by contacting it with a pH stabilizer in the adsorber 9 with a filling volume of 0.2 dm ³ .

The stabilization of the phenol solution is carried out at a temperature of 72 ° C using a filling identical to that used to stabilize the pH level of the stream containing the synthesis products in adsorber 6 (signs of adsorber filling are presented in table 7). The mixture is continuously fed into the adsorber 9 at a flow rate of 1.2 m / h. The phenol solution after adsorber 9 with a pH of 5.5 units in an amount of 0.372 kg / h is then mixed with distillate (0.496 kg / h) from distillation column 7 (the composition of the distillate is shown in table 8).

The mixture in an amount of 0.868 kg / h, the following composition: water 5.27%, acetone 5.02% and phenol 89.71% is subjected to distillation in order to separate post-reaction water, so that phenol and acetone can be returned to the reaction system. The separation of the mixture of acetone, water and phenol is carried out in a system of two columns 10 with a structural filler, and in the first column, the mixture is divided into phenol and a fraction of water and acetone, and in the second, acetone is separated from this fraction. The composition of the individual flows of the distillation separation of a solution of acetone, water and phenol is presented in Table 9. p, the p-isomer of DPP is the main synthesis product, is isolated in crystallizers 8 by a two-stage crystallization method, which consists of a combination of suspension and fractional crystallizations.

For suspension crystallization of the adduct of bisphenol A / phenol, a concentrated mixture of the products shown in table 8 is used in an amount of 1.804 kg / h. The crystallization operation is carried out in the mold 8.

In a mixing mold with a heating and cooling jacket and the ability to precisely control the temperature of the liquid in the range from 20 to 100 ° C, at a temperature of 80 ° C the following flows are mixed:

- a stream of concentrated products to isolate the p, p-isomer of the DPP column 7 in an amount of 1.804 kg / h;

- part of the post-crystallization solutions that underwent isomerization of the o, p-isomer of DPP in the amount of 0.620 kg / h;

- effluent after fractional crystallization from the melt in an amount of 0.021 kg / h

After thoroughly mixing the components and obtaining a homogeneous composition, the contents of the mold are cooled at a rate of 7 ° C per hour in the range from 80 ° C to 52 ° C.

Crystallization of the adduct of bisphenol A / phenol from the solution is completed when the temperature reaches 52 ° C. The crystals of the adduct of bisphenol A / phenol are separated from the post-crystallization solutions by filtration. For phase separation, a filter press with a baffle with a filter mesh size of 10 μm is used. Filtration is carried out in an inert atmosphere of nitrogen at a temperature of 52 ° C.

Part of the post-crystallization solutions is returned to the reaction system, to mixer 2, and for the rest of the solutions (0.886 kg / h), concentration is carried out, then the о, p-isomer of DPP is isomerized to p, p-isomer of DPP, after which the solution enriched in p, p the isomer of DPP, completely returns to the stage of suspension crystallization. The crystals of the adduct in the amount of 0.483 kg / h are transferred to the evaporation unit, and then melted at a temperature of 110 ° C and the composition is equalized. The crude p, p-isomer of DPP is obtained by thermal decomposition of the adduct at a temperature of more than 120 ° C and the gradual distillation of phenol. Phenol distillation is carried out at a reduced pressure of 25 mm Hg. In the process of phenol distillation, the temperature gradually rises from 110 ° C to 165 ° C at a rate of 50 ° C per hour. Decomposition of the adduct is completed when the phenol content of bisphenol A decreases to 0.07%. As a result of the decomposition of the adduct, 0.315 kg / h of crude bisphenol A is obtained, which is then purified by fractional crystallization in a tube crystallizer. After purification by fractional crystallization, the final product is obtained - 0.294 kg / h of bisphenol A with the parameters shown in table 10.

Claims (12)

1. The method of producing bisphenol A through the condensation reaction of acetone with phenol in the presence of strongly acidic sulfonated ion-exchange resins, characterized in that: - a reaction mixture containing acetone, phenol and phenol-acetone reaction products is brought into contact with an ion exchange catalyst in at least two reactors until the total water content is not more than 2.5 g / g, and acetone and phenol are introduced into the reactor (1), and the post-reaction mixture from the reactor (1) mixed in the mixer (2) with the post-crystallization solutions from crystallizers (8) and acetone is introduced into the reactor (3); - the post-reaction mixture after the reactor (3) is mixed in a mixer (4) with a part of a phenol solution of not more than 40 g / g, obtained as a result of contact of the dehydration mixture containing not more than 1.0% water with an ion-exchange catalyst in at least one reactor (5); - the post-reaction mixture from the mixer (4) is brought into contact in the adsorber (6) at a temperature of not more than 150 ° C and with a flow velocity of not more than 10 m / h with a stabilizer of the pH level of a phenol solution in the form of a constant layer with a grain size of not more than 1, 2 mm, including carboxyl and / or hydroxyl and / or amide groups, until the post-reaction mixture reaches a pH of 5-6 units after the adsorber (6); - carry out the concentration of the post-reaction mixture from the adsorber (6) in the distillation column (7) by partial or complete evaporation of volatile substances such as distillate containing phenol, acetone and water at a boiling point at normal pressure of not more than 200 ° C, and crystallize bisphenol A from the distillation residue; - at least 60% phenol solution from the reactor (5) is brought into contact in the adsorber (9) at a temperature of not more than 150 ° C and a flow velocity of not more than 10 m / h with a pH stabilizer of the phenol solution in the form of a constant layer with grain size not more than 1.2 mm containing carboxyl and / or hydroxyl and / or amide groups until the mixture reaches a pH value of 5-6 units after the adsorber (9), and the resulting solution is mixed with distillate from a distillation column (7) containing phenol, acetone and water, and sent to a distillation column (10); - phenol isolated in the column (10) is returned to the reactor (1), acetone to the reactor (1) and / or (3), and the aqueous fraction is removed from the installation in the form of waste water. 2. The method according to p. 1, characterized in that the dehydration mixture containing not more than 1 sg / g of water is brought into contact with the ion exchange catalyst in the reactor (5) at a temperature of not more than 95 ° C and with a flow rate of not more than 2, 0 m / h 3. The method according to p. 1, characterized in that the reaction mixture in the reactors (1) and (3) is brought into contact with the ion exchange catalyst at a temperature of not more than 85 ° C and with a flow velocity of not more than 6 m / h. 4. The method according to p. 1, characterized in that in each of the reactors, depending on the needs, you can send the reaction mixture or dehydration mixture. 5. The method according to p. 1, characterized in that they use a pH stabilizer solution of phenol with a molar ratio of hydroxyl (-OH) groups and carboxyl (-COOH) groups of not more than 1: 1. 6. The method according to p. 1, characterized in that they use a pH stabilizer of a phenol solution with a molar ratio of amide (-CONH2) groups and carboxyl (-COOH) groups of not more than 1: 2.

Images