Catalyst for synthesizing bisphenol A-bis (diphenyl phosphate) and synthesis method

Abstract

The invention belongs to the field of organic synthesis, and relates to a catalyst for synthesizing bisphenol A-bis (diphenyl phosphate) and a synthesis method, a titanium-magnesium composite catalyst and two-stage trickle bed cascade reaction process is adopted, and the titanium-magnesium composite catalyst is filled in two stages of trickle beds. Phosphorus oxychloride and a bisphenol A solution are introduced into the first-stage trickle bed reactor, nitrogen is introduced at the same time, a reaction is conducted at the temperature of 80-100 DEG C, an intermediate is obtained, and the molar ratio of phosphorus oxychloride to bisphenol A is 2: 1; the intermediate and molten phenol are introduced into the second-stage trickle bed reactor, nitrogen is introduced into the second-stage trickle bed reactor at the same time, a reaction is conducted at the temperature of 140-160 DEG C, and the molar ratio of phenol to bisphenol A is (4-5): 1. The titanium-magnesium composite catalyst is combined with the tandem trickle bed reaction process, and the prepared product is high in purity, low in impurity content and low in chromaticity.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis, specifically relating to a catalyst and synthesis method for synthesizing bisphenol A-bis(diphenyl phosphate). Background Technology

[0002] Bisphenol A-bis(diphenyl phosphate), abbreviated as BDP, is a condensation-polymerized aryl phosphate ester with characteristics such as halogen-free, low smoke, environmental friendliness, and high limiting oxygen index. It is widely used in various polymer engineering plastics such as PC, ABS, and nylon. With increasing environmental requirements in plastic processing, halogen-free flame retardants have become a new trend, and BDP, due to its outstanding flame retardant properties, thermal stability, and good compatibility, has a broad market prospect. Traditional processes often use Lewis acid catalysis (such as magnesium chloride and aluminum chloride), but these methods have the following problems: 1. High rate of byproduct polymer formation leads to insufficient product purity; 2. Post-reaction processing is prone to emulsification, resulting in significant yield loss; 3. The product's color intensity is too high (APHA > 50), requiring an additional decolorization step. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a catalyst and synthesis method for synthesizing bisphenol A-bis(diphenyl phosphate), which can solve the problems of high impurity content and poor color in the preparation of bisphenol A-bis(diphenyl phosphate) by the prior art.

[0004] This invention is achieved through the following technical solution: The first aspect of the present invention is to provide a catalyst for the synthesis of bisphenol A-bis(diphenyl phosphate), which is a titanium-magnesium composite catalyst. The preparation method of the titanium-magnesium composite catalyst is as follows: titanium tetrachloride is pre-cooled to -5-0°C, and magnesium chloride is added under stirring; the temperature is gradually increased to 75-85°C, a silane modifier is added, the temperature is maintained for 0.5-1.5 hours, and the titanium-magnesium composite catalyst is obtained after washing. The volume-to-mass ratio of titanium tetrachloride to magnesium chloride is 2.5-3.5 L / kg.

[0005] Furthermore, the silane modifier is bis(trifluoromethanesulfonyl)dimethylsilane, and the amount of bis(trifluoromethanesulfonyl)dimethylsilane used is 1-5% of the mass of magnesium chloride.

[0006] The second aspect of the present invention is to provide a highly efficient catalytic synthesis method for bisphenol A-bis(diphenyl phosphate), which employs a two-stage trickle bed tandem reaction process, wherein both stages of the trickle bed are filled with a titanium-magnesium composite catalyst.

[0007] The first-stage trickle bed reactor is fed with phosphorus oxychloride and bisphenol A solution, and nitrogen gas is introduced at the same time. The reaction is carried out at 80-100℃ to obtain an intermediate. The molar ratio of phosphorus oxychloride to bisphenol A is 2:1. The intermediate and molten phenol are introduced into the second-stage trickle bed reactor, and nitrogen is introduced at the same time. The reaction is carried out at 140-160℃, and the molar ratio of phenol to bisphenol A is 4-5:1. The liquid product from the second-stage trickle bed reactor is passed through a falling film evaporator to remove phenol and obtain crude bisphenol A-bis(diphenyl phosphate). The crude bisphenol A-bis(diphenyl phosphate) is then washed sequentially with acid washing solution, alkali washing solution, and water until the pH of the aqueous layer reaches 7. The oil phase after phase separation is then dehydrated by distillation to obtain the bisphenol A-bis(diphenyl phosphate) product.

[0008] Furthermore, the flow rate of phosphorus oxychloride is 0.5-1 kg / h, and the flow rate of bisphenol A solution is 2-3 kg / h.

[0009] Furthermore, the solvent of the bisphenol A solution is bisphenol A-bis(diphenyl phosphate), and the mass percentage of bisphenol A is 20-30%.

[0010] Furthermore, the effluent from the first-stage trickle bed reactor undergoes gas-liquid separation, with the liquid entering the second-stage trickle bed reactor and the gas being transported to the alkali spray absorption tower.

[0011] Furthermore, the nitrogen flow rate in the first-stage trickle bed reactor is controlled at 0.4-0.6 L / h.

[0012] Furthermore, the flow rate of the intermediate is controlled at 2-4 kg / h and the flow rate of molten phenol is controlled at 1-1.2 kg / h in the second-stage trickle bed reactor.

[0013] Furthermore, the effluent from the second-stage trickle bed reactor is separated by a gas-liquid separator, with the liquid entering a falling film evaporator and the gas being transported to an alkali spray absorption tower.

[0014] Furthermore, the falling film evaporator has a vacuum degree of -0.08 to -0.1 MPa and a temperature controlled at 120~140℃.

[0015] The relevant chemical reaction formulas involved in this invention are as follows:

[0016]

[0017] Traditional methods for preparing the flame retardant BDP often use Lewis acids such as anhydrous magnesium chloride or anhydrous aluminum chloride as catalysts. These catalysts tend to emulsify during water washing, increasing the difficulty of post-processing. Furthermore, these catalysts have very low solubility in the product, and their residue can lead to low light transmittance and poor color. This invention uses a titanium-magnesium composite catalyst combined with a series trickle-bed reaction process. The reaction is heterogeneous, eliminating the need for acid washing to remove the catalyst. Simultaneously, due to the high catalyst activity, the reaction conversion rate and selectivity are high, resulting in a product with high purity, low impurity content, and low color.

[0018] Advantages and beneficial effects of the present invention: 1. This invention uses a titanium-magnesium composite catalyst combined with a series trickle bed reaction process to produce a product with high purity, low impurity content, and low color.

[0019] 2. This invention uses a titanium-magnesium composite catalyst, which improves reaction efficiency, effectively reduces the amount of phosphorus oxychloride used, avoids the need for distillation to recover phosphorus oxychloride during the process, and improves production efficiency.

[0020] 3. This invention uses product BDP as a solvent to dissolve the raw material bisphenol A, enabling the material to be transported by a pump, thereby achieving continuous operation and shortening the production cycle. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a dual-trickling bed reaction system; Figure 2 This is a liquid chromatogram of BDP, the product of Example 1 of the present invention; Figure 3 H is the product BDP of Example 1 of this invention. 1 NMR spectrum; Figure 4 The thermogravimetric spectrum of BDP, the product of Example 1 of this invention; Figure 1 In the diagram: 1 is the #1 trickle bed reactor, 2 is the #1 gas-liquid separator, 3 is the #2 trickle bed reactor, 4 is the #2 gas-liquid separator, and 5 is the falling film evaporator. Detailed Implementation

[0022] The following examples further illustrate the above-described content of the present invention, but it should not be construed as limiting the scope of the subject matter of the present invention to the following examples. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention.

[0023] Example 1 Catalyst preparation 30L of titanium tetrachloride was added to a 100L enamel-lined reactor. Chilled water was circulated through the jacket, and the mixture was stirred and cooled to -5℃. 10kg of spherical magnesium chloride was added to the pre-cooled titanium tetrachloride. After thorough stirring, the temperature was increased to 25℃ at a rate of 1℃ / 5min, and stirred for 1 hour. The mixture was then heated to 80℃, and 0.365kg of bis(trifluoromethylsulfonyl)dimethylsilane was added. After heating for 1 hour, the mixture was cooled to room temperature. The supernatant was filtered off, and the mixture was washed three times with 100L of hexane until clear. The solution was then dried to obtain a light green spherical solid catalyst.

[0024] Synthesis of Bisphenol A-bis(diphenyl phosphate) (BDP) 5 kg of the above-mentioned catalyst was loaded into Trickle Bed Reactor 1 (first-stage Trickle Bed Reactor), and the reactor was preheated to 95°C. 6 kg of the above-mentioned catalyst was loaded into Trickle Bed Reactor 3, and the reactor was preheated to 150°C. 22.8 kg of bisphenol A was added to 69.6 kg of bisphenol A-bis(diphenyl phosphate), and the mixture was heated to 80°C and stirred thoroughly until the bisphenol A was completely dissolved. This was used as feed a, and phosphorus oxychloride was used as feed b. Both feeds were fed into Trickle Bed Reactor 1 via metering pumps for esterification. The feed rate for feed a was 2.31 kg / h (2.5 mol / h for bisphenol A), and the feed rate for feed b was 0.765 kg / h (5 mol / h). Simultaneously, nitrogen gas was introduced into Trickle Bed Reactor 1 via a mass flow meter at a flow rate of 0.5 L / h. The effluent from Trickle Bed Reactor 1 is separated by Gas-Liquid Separator 2 (1#). The gas is removed by alkali spray absorption, and the liquid material (2.8925 kg / h) and molten phenol (material c) are fed into Trickle Bed Reactor 3 (2# Trickle Bed Reactor, second-stage). The feed rate of material c is 1.13 kg / h (12 mol / h). The temperature inside the second-stage trickle bed reactor is controlled at 150℃. Simultaneously, nitrogen gas is introduced into Trickle Bed Reactor 3 through a mass flow meter at a flow rate of 1.0 L / h. The effluent from Trickle Bed Reactor 3 is separated by Gas-Liquid Separator 4 (2#). The gas is removed by alkali spray absorption, and the liquid material passes through Falling Film Evaporator 5 to remove phenol. The vacuum degree is -0.09 MPa, and the temperature is 130℃, yielding crude BDP. The crude product is then washed sequentially with 3 wt% hydrochloric acid aqueous solution and 4 wt% sodium hydroxide aqueous solution, and finally washed with water until the pH of the aqueous layer reaches 7. After water washing and phase separation, the oil phase was dehydrated by distillation to obtain 135.5 kg of BDP product, of which the BDP content was 99.5% and the color number (APHA) was 25. After deducting the BDP added as solvent, the BDP yield was 93.7%.

[0025] Example 2 Using the same catalyst as in Example 1, 4 kg of catalyst was preheated to 80°C in Trickle Bed Reactor 1 (No. 1); 5 kg of catalyst was preheated to 140°C in Trickle Bed Reactor 3 (No. 2). A feedstock a (24 kg BDP + 6 kg bisphenol A) with a bisphenol A content of 20% by mass was prepared. The feed flow rate of feedstock a was 3 kg / h (bisphenol A 2.63 mol / h), the flow rate of feedstock b (phosphorus oxychloride) was 0.805 kg / h (5.26 mol / h), and the nitrogen flow rate was 0.4 L / h. After separation from the feedstock in Trickle Bed Reactor 1, the liquid (3.61 kg / h) and feedstock c (molten phenol, flow rate 1 kg / h, phenol:bisphenol A molar ratio = 4:1) entered Trickle Bed Reactor 3 (No. 2), with a nitrogen flow rate of 0.8 L / h. The feedstock from Trickle Bed Reactor 3 was dephenolized in a falling film evaporator 5 (vacuum degree -0.08 MPa, temperature 120°C) to obtain the crude product. Acid washing (2wt% hydrochloric acid), alkali washing (3wt% sodium hydroxide), and water washing until pH=7 were performed. Distillation and dehydration yielded 41.37 kg of BDP product. Analysis: BDP content 98.8%, color number APHA 35, yield 92.1% (excluding solvent).

[0026] Example 3 Using the same catalyst as in Example 1, 6 kg of catalyst was preheated to 100°C in Trickle Bed Reactor 1 (No. 1), and 7 kg of catalyst was preheated to 160°C in Trickle Bed Reactor 3 (No. 2). A feedstock (35 kg BDP + 15 kg BDP) containing 30% bisphenol A was prepared. Feedstock a was fed at a rate of 2.2 kg / h (2.89 mol / h of bisphenol A), feedstock b (phosphorus oxychloride) at a rate of 0.884 kg / h (5.78 mol / h), and nitrogen flow rate was 0.6 L / h. 2.87 kg / h of liquid from Trickle Bed Reactor 1 and feedstock c (phenol flow rate 1.14 kg / h, phenol:bisphenol A molar ratio = 4.2:1) were fed into Trickle Bed Reactor 3, with a nitrogen flow rate of 1.2 L / h. Falling film evaporation conditions: vacuum -0.1 MPa, temperature 140°C. After washing and purification, 78.58 kg of BDP product was obtained. Analysis: BDP content 99.2%, color number APHA 28, yield 93.8% (excluding solvent).

[0027] Comparative Example 1 Magnesium chloride was used as a catalyst. The magnesium chloride was purchased from Sinopharm Reagent. The same two-stage trickle-bed tandem reaction process as in Example 1 was employed to obtain 129 kg of BDP product. Analysis: BDP content 97.8%, color number APHA50, yield 81.3% (excluding solvent).

[0028] Comparative Example 2 Titanium silicate molecular sieve was used as a catalyst. The titanium silicate molecular sieve was purchased from Nankai Catalyst Factory. The same two-stage trickle bed series reaction process as in Example 1 was used to obtain 131.8 kg of BDP product. Analysis: BDP content 97.9%, color number APHA55, yield 85.4% (excluding solvent).

[0029] Comparative Example 3 Using the same catalyst as in Example 1, 69.6 kg of bisphenol A-bis(diphenyl phosphate), 22.8 kg of bisphenol A and 0.5 kg of titanium-magnesium composite catalyst were sequentially added to the first reactor. The air in the first reactor was replaced with nitrogen. The material in the first reactor was then heated to 80°C, and 30.6 kg of phosphorus oxychloride was added dropwise. After the addition was completed, the reaction was maintained at this temperature for 5 hours. The material discharged from the first reactor was filtered to obtain the BDP intermediate. 115.7 kg of BDP intermediate, 47 kg of phenol, and 0.8 kg of titanium-magnesium composite catalyst were sequentially added to the second reactor. The air in the first reactor was replaced with nitrogen. The material in the first reactor was then heated to 150°C and reacted for 6 hours. The material from the second reactor was filtered to obtain crude BDP. The crude product was then washed sequentially with 3wt% hydrochloric acid aqueous solution and 4wt% sodium hydroxide aqueous solution, and finally washed with water until the pH of the aqueous layer reached 7. The oil phase after water washing and phase separation was dehydrated by distillation to obtain 132.5 kg of BDP product, with a BDP content of 98.2% and a color number (APHA) of 55. After deducting the amount of BDP added as solvent, the BDP yield was 86.9%.

[0030] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the inventive concept, and these all fall within the protection scope of the present invention.

Claims

1. A catalyst for the synthesis of bisphenol A-bis(diphenyl phosphate), characterized in that, The titanium-magnesium composite catalyst is prepared by pre-cooling titanium tetrachloride to -5 to 0°C, adding magnesium chloride under stirring; gradually heating to 75-85°C, adding silane modifier, maintaining the temperature for 0.5-1.5 hours, and washing to obtain the titanium-magnesium composite catalyst. The volume-to-mass ratio of titanium tetrachloride to magnesium chloride is 2.5-3.5 L / kg.

2. The catalyst according to claim 1, characterized in that, The silane modifier is bis(trifluoromethanesulfonyl)dimethylsilane, and the amount of bis(trifluoromethanesulfonyl)dimethylsilane used is 1-5% of the mass of magnesium chloride.

3. A method for synthesizing bisphenol A-bis(diphenyl phosphate) using the catalyst according to any one of claims 1-2, characterized in that, A two-stage trickle bed series reaction process is adopted, and titanium-magnesium composite catalysts are packed in both trickle beds; The first-stage trickle bed reactor is fed with phosphorus oxychloride and bisphenol A solution, and nitrogen gas is introduced at the same time. The reaction is carried out at 80-100℃ to obtain an intermediate. The molar ratio of phosphorus oxychloride to bisphenol A is 2:

1. The intermediate and molten phenol are introduced into the second-stage trickle bed reactor, and nitrogen is introduced at the same time. The reaction is carried out at 140-160℃, and the molar ratio of phenol to bisphenol A is 4-5:

1. The liquid product from the second-stage trickle bed reactor is passed through a falling film evaporator to remove phenol and obtain crude bisphenol A-bis(diphenyl phosphate). The crude bisphenol A-bis(diphenyl phosphate) is then washed sequentially with acid washing solution, alkali washing solution, and water until the pH of the aqueous layer reaches 7. The oil phase after phase separation is then dehydrated by distillation to obtain the bisphenol A-bis(diphenyl phosphate) product.

4. The synthesis method according to claim 3, characterized in that, The flow rate of phosphorus oxychloride is 0.5-1 kg / h, and the flow rate of bisphenol A solution is 2-3 kg / h.

5. The synthesis method according to claim 3, characterized in that, The solvent for the bisphenol A solution is bisphenol A-bis(diphenyl phosphate), and the mass percentage of bisphenol A is 20-30%.

6. The synthesis method according to claim 3, characterized in that, The effluent from the first-stage trickle bed reactor undergoes gas-liquid separation, with the liquid entering the second-stage trickle bed reactor and the gas being transported to the alkali spray absorption tower.

7. The synthesis method according to claim 3, characterized in that, In the first-stage trickle bed reactor, the nitrogen flow rate is controlled at 0.4-0.6 L / h, and in the second-stage trickle bed reactor, the nitrogen flow rate is controlled at 0.8-1.2 L / h.

8. The synthesis method according to claim 3, characterized in that, In the second-stage trickle bed reactor, the flow rate of the intermediate is controlled at 2-4 kg / h, and the flow rate of molten phenol is 1-1.2 kg / h.

9. The synthesis method according to claim 3, characterized in that, The effluent from the second-stage trickle bed reactor is separated by a gas-liquid separator. The liquid enters the falling film evaporator, while the gas is transported to the alkali spray absorption tower.

10. The synthesis method according to claim 9, characterized in that, The falling film evaporator has a vacuum of -0.08 to -0.1 MPa and a temperature controlled at 120~140℃.

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