Method for recycling phosphoric acid catalyst for bisphenol F synthesis

Abstract

The invention belongs to the technical field of catalysts, and discloses a method for recycling a phosphoric acid catalyst for bisphenol F synthesis. Comprising the following steps: (1) reacting phenol, an acid catalyst and a formaldehyde aqueous solution to obtain a bisphenol F reaction solution; (2) the bisphenol F reaction liquid enters a liquid separation system I, and an oil phase I and a water phase I are obtained under certain conditions; (3) the oil phase I enters a multi-stage extraction water washing system for extraction water washing to obtain extraction water washing liquid; (4) the extraction water washing liquid enters a liquid separation system II, and an oil phase II and a water phase II are obtained; and (5) uniformly mixing the water phase I and the water phase II in a storage tank, feeding the mixture into an evaporation system for evaporation and concentration, directly feeding recycled phosphoric acid into a reaction system, and feeding distilled condensate into a clean water recycling section. The phosphoric acid catalyst can be completely recycled, and the method has the advantages of being short in technological process, small in waste water amount and free of solid waste.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and more particularly to a method for recycling and reusing a phosphoric acid catalyst for bisphenol F synthesis. Background Art

[0002] Currently, under high phenol-formaldehyde ratio conditions, bisphenol F monomers are synthesized by the acid-catalyzed reaction of phenol and formaldehyde. The use of a phosphoric acid catalyst has the advantages of fewer side reactions, high bisphenol F monomer yield (>95%), high para-BPF content (40-45%), and low oligomer content. After the bisphenol F synthesis reaction is completed, the phosphoric acid catalyst will cause side reactions during the subsequent product separation and purification process, resulting in an increase in oligomers and a decrease in the bisphenol F monomer yield. Therefore, after the bisphenol F synthesis reaction is completed, the phosphoric acid catalyst needs to be removed in a timely manner.

[0003] The existing technology uses an alkali neutralization method to remove the residual phosphoric acid catalyst, which has the disadvantages of a long catalyst recovery process, incomplete removal of phosphoric acid, a large amount of wastewater, and the generation of phosphate / phenolate solid waste.

[0004] Therefore, it is an urgent problem for those skilled in the art to develop a method with a short process flow, less wastewater, no solid waste generation, and all phosphoric acid catalysts can be recycled and reused. Summary of the Invention

[0005] In view of this, the present invention provides a method for recycling and reusing a phosphoric acid catalyst for bisphenol F synthesis, which adopts a multi-stage extraction and water washing integrated process, omits the alkali neutralization reaction, and has the advantages of a short process flow, less wastewater, no solid waste generation, and all phosphoric acid catalysts can be recycled and reused.

[0006] In order to achieve the above object, the present invention provides a method for recycling and reusing a phosphoric acid catalyst for bisphenol F synthesis, comprising the following steps:

[0007] (1) Mix phenol, an acid catalyst, and an aqueous formaldehyde solution, and carry out a condensation reaction under certain conditions to obtain a bisphenol F reaction solution;

[0008] (2) The bisphenol F reaction solution enters the liquid separation system I, and at a certain liquid separation temperature and time, an oil phase I containing bisphenol F, unreacted phenol, a small amount of oligomers, and a small amount of phosphoric acid solution is obtained, and at the same time, an aqueous phase I containing a certain amount of phenol and a large amount of phosphoric acid aqueous solution is obtained;

[0009] (3) The oil phase I enters the multi-stage extraction and water washing system, and is extracted and washed with a solvent / water mixture to obtain an extraction and water washing solution;

[0010] (4) The extracted and washed liquid enters the liquid separation system II, and after standing, an oil phase II containing bisphenol F, unreacted phenol, and a small amount of oligomers is obtained for subsequent separation and purification section; meanwhile, an aqueous phase II containing a small amount of phenol and a large amount of phosphoric acid aqueous solution is obtained;

[0011] (5) The aqueous phase I and the aqueous phase II are mixed evenly in a storage tank, and then enter an evaporation system for evaporation and concentration. The recovered phosphoric acid directly enters the reaction system, and the distillation condensate enters the clear water recycling section.

[0012] Preferably, in step (1), the molar ratio of the phenol to formaldehyde is 5:1 to 15:1, and the molar ratio of the phenol to the acid catalyst is 5:1 to 15:1;

[0013] The concentration of the aqueous formaldehyde solution is 27 - 37%;

[0014] The acid catalyst is phosphoric acid;

[0015] The temperature of the condensation reaction is 40 - 90 °C, and the reaction time is 0.5 - 7 h.

[0016] Preferably, in step (2), the temperature of the liquid separation is 50 - 90 °C, and the liquid separation time is 0.5 - 3 h.

[0017] Preferably, in step (3), the solvent is one or a mixture of solvents such as benzene, toluene, xylene, n - hexane, cyclohexane, and methyl isobutyl ketone;

[0018] The volume ratio of the solvent to water is 0.5:1 to 5:1; the volume ratio of the oil phase I to the solvent is 0.2:1 to 2:1;

[0019] The extraction and washing temperature is 40 °C - 90 °C; the number of multi - stage extractions is 2 - 6 times.

[0020] The inventive concept of the above technical means is as follows:

[0021] The solvent selected in the present invention is immiscible with phosphoric acid, completely miscible with organic components such as phenol and bisphenol F in the reaction solution, phosphoric acid is completely miscible with water, and the solvent is completely immiscible with water. Based on the above concept, the solvent can easily extract the organic matter in the reaction solution into the oil phase. Under the dual effects of the immiscibility of phosphoric acid with the solvent but complete miscibility with water, and the immiscibility of the solvent with water but complete miscibility with organic matter, it is convenient to make the phosphoric acid in the reaction solution enter the water phase easily, and at the same time, the organic phase in the reaction solution enters the solvent to form an oil phase, so as to remove the phosphoric acid in the oil phase II by multi - stage extraction and washing.

[0022] Preferably, in step (4), the residual phosphoric acid content in the oil phase II is less than 5 ppm - 50 ppm.

[0023] Preferably, in step (5), in the recovered phosphoric acid, the recovery rate of phosphoric acid is greater than 99.5% - 99.9%, and the concentration of phosphoric acid is 70% - 86%.

[0024] As can be seen from the above technical solutions, compared with the prior art, the beneficial effects obtained by the present invention are as follows:

[0025] (1) In the prior art, the oil phase I coming out of the liquid separation system I enters the alkali neutralization system, and the alkali will neutralize phosphoric acid and part of the raw material phenol, generating solid waste of phosphate and phenolate, resulting in incomplete recovery of phosphoric acid in the oil phase. In the present invention, a multi-stage extraction and water washing system is adopted to recover almost all phosphoric acid without generating solid waste salts.

[0026] (2) In the prior art, the method of using alkali to neutralize phosphoric acid to remove residual phosphoric acid is adopted, but the phenolic substances in the reaction solution also belong to weak acids and can compete with the alkali in the reaction, resulting in incomplete reaction of part of the phosphoric acid and the risk of residual phosphoric acid. The present invention adopts a solvent that has a strong extraction effect on phenol and is immiscible with water. The residual phosphoric acid is completely dissolved in water, and the phosphoric acid in the oil phase I can be completely removed, realizing the complete recovery and reuse of phosphoric acid.

[0027] (3) In the prior art, a set of evaporation system is required for the concentration of recovered phosphoric acid, a new neutralization reaction system is added, and a new evaporation system is required for the salt-containing aqueous phase obtained after the neutralization reaction, resulting in a longer process flow. The present invention does not have a neutralization reaction. After extraction and water washing, the aqueous phase only contains phosphoric acid, and only one set of phosphoric acid recovery evaporation system is required, simplifying the process flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0029] Figure 1 It is a simplified flow chart of a method for producing bisphenol F.

[0030] Figure 2 It is a simplified flow chart of a method for producing bisphenol F according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0032] Example 1

[0033] In the reaction system, a certain amount of phenol was added to a reactor equipped with a stirrer, heated until the phenol was completely melted, a certain amount of acid catalyst was added, and after stirring evenly, 37% formaldehyde solution was added dropwise. After reacting for a certain time at a certain temperature, the yield of bisphenol F and the content of 4,4'-BPF were detected. The results are shown in Tables 1 to 4.

[0034] Table 1 corresponds to a molar ratio of phenol to formaldehyde of 10:1, a molar ratio of phenol to acid catalyst of 10:1, and a reaction time of 3 h.

[0035] Influence of reaction temperature in Table 1

[0036]

[0037] Table 2 corresponds to a molar ratio of phenol to formaldehyde of 10:1, a molar ratio of phenol to acid catalyst of 10:1, and a reaction temperature of 65 °C.

[0038] Influence of reaction time in Table 2

[0039]

[0040] Table 3 corresponds to a molar ratio of phenol to acid catalyst of 10:1, a reaction temperature of 65 °C, and a reaction time of 3 h.

[0041] Influence of phenol-formaldehyde ratio in Table 3

[0042]

[0043] Table 4 corresponds to a molar ratio of phenol to formaldehyde of 10:1, a reaction temperature of 65 °C, and a reaction time of 3 h.

[0044] Influence of phenol-acid ratio in Table 4

[0045]

[0046] Example 2

[0047] After the synthesis reaction of bisphenol F is completed (corresponding molar ratios of phenol / acetic acid catalyst of 10:1, phenol / formaldehyde of 10:1, reaction temperature of 65 °C, and reaction time of 3 h), it enters the liquid separation system I. While maintaining heating at 65 °C, the reaction solution is allowed to stand and separate into layers. The lower layer of phosphoric acid is directly separated by liquid separation. After separation, the aqueous phase I containing the phosphoric acid solution is obtained, the phosphoric acid concentration is measured, and the phosphoric acid recovery rate is calculated. The results are shown in Table 5, and the average phosphoric acid recovery rate for a single liquid separation is 83.7%.

[0048] Table 5 Single-stage phosphoric acid recovery rate of liquid separation system I

[0049] Number of experiments Static temperature / °C Phosphoric acid recovery rate / % 1 65 82.1 2 65 83.5 3 65 85.4

[0050] Example 3

[0051] The organic phase reaction liquid oil phase I obtained from the liquid separation section enters the multi-stage extraction and water washing system. At a certain temperature, a solvent is added as the extractant and pure water for extraction and washing (a total of 3 extractions), and then it enters the liquid separation system II. After standing, the aqueous phase raffinate is taken and the phosphoric acid concentration is measured, and the phosphoric acid recovery rate is calculated. The results of the phosphoric acid recovery rate in the first stage of extraction are shown in Table 6.

[0052] Table 6 Single-stage phosphoric acid recovery rate in the multi-stage extraction and water washing system

[0053]

[0054] Example 4

[0055] In the reaction system, after reacting for 3 h under the conditions of a reaction temperature of 65 °C, a phenol / formaldehyde ratio of 10:1, and a phenol / acetic acid ratio of 10:1, the oil phase I obtained by entering the liquid separation system I enters the multi-stage extraction and water washing system. Extraction and washing are carried out three times at a temperature of 65 °C, with a solvent / water volume ratio of 1:1 and an oil phase I / solvent volume ratio of 1:1. Then it enters the liquid separation system II. After standing at 65 °C, the oil phase II is obtained, and the residual phosphoric acid content is measured. The extraction and liquid separation results under different solvent conditions are shown in Table 7.

[0056] Table 7 Influence of different solvents on the residual phosphoric acid in the oil phase

[0057] Solvent None Cyclohexane Toluene Xylene Ethyl acetate Residual phosphoric acid / ppm >10000 500～1000 50～150 5-100 1000～2000

[0058] Example 5

[0059] The phosphoric acid recovered by the evaporation system is used for the synthesis of bisphenol F: A certain amount of phenol is added to a reactor equipped with a stirrer and heated until the phenol is completely melted. The recovered phosphoric acid with a certain concentration is added, and after stirring evenly, a 37% formaldehyde solution is added dropwise. After reacting for 3 h under the conditions of a reaction temperature of 65 °C, a phenol / formaldehyde ratio of 10:1, and a phenol / acetic acid ratio of 10:1, the yield of bisphenol F and the content of 4,4'-BPF are detected. The results are shown in Table 8.

[0060] Table 8 Influence of Recycled Phosphoric Acid Concentration on the Bisphenol F Reaction

[0061] Serial number Phosphoric acid concentration BPF yield / % 4,4’-BPF content / % 1 70％ 89.3 45.6 2 75％ 92.6 44.7 3 80％ 99.5 43.2

[0062] Comparative Example

[0063] Add a certain amount of phenol into a reactor equipped with a stirrer, heat it until the phenol completely melts, add a certain amount of recycled phosphoric acid, stir evenly, then dropwise add 37% formaldehyde solution. After reacting for 3 h under the conditions of a reaction temperature of 65 °C, a phenol-formaldehyde ratio of 12:1, and a phenol-acid ratio of 10:1, keep it standing and separating at 65 °C, directly separate the liquid. For the lower-layer phosphoric acid solution and the upper-layer oil phase, wash it three times with water of equal volume, collect the phosphoric acid solution, detect the phosphoric acid content, and calculate the phosphoric acid recovery rate. After washing with water, neutralize the oil phase with alkali, determine the reaction end point by potentiometric titration, then wash it three times with water of equal volume, collect the salt solution, rotary evaporate and dry it, weigh the salt mass, and calculate the salt production amount for synthesizing 100 g of bisphenol F. The results are shown in Table 9.

[0064] Table 9 Influence of Recycled Phosphoric Acid Concentration on the Bisphenol F Reaction

[0065]

[0066]

[0067] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for recovering and reusing a phosphoric acid catalyst for synthesizing bisphenol F, characterized in that: The following steps are involved: (1) mixing phenol, an acid catalyst and a formaldehyde aqueous solution, and reacting them under certain conditions to obtain a bisphenol F reaction solution; (2) the bisphenol F reaction liquid enters the liquid separation system I, and at a certain liquid separation temperature and time, an oil phase I and a water phase I are obtained at the same time; (3) the oil phase I enters a multi-stage extraction and water washing system, and is extracted and washed with a solvent / water mixture to obtain an extraction water washing liquid; (4) The extracted water washing liquid enters the liquid separation system II, and is left to stand to obtain the oil phase II, which is used for the subsequent separation and refining process; at the same time, the water phase II is obtained; (5) The aqueous phase I and the aqueous phase II are mixed evenly in a storage tank, and then sent to an evaporation system for evaporation and concentration. The recovered phosphoric acid directly enters the reaction system, and the distillation condensate enters the clean water reuse section.

2. The method for recovering and reusing the phosphoric acid catalyst for bisphenol F synthesis according to claim 1, characterized in that: In step (1), the molar ratio of phenol to formaldehyde is 5:1 to 15:1, and the molar ratio of phenol to acid catalyst is 5:1 to 15:1; The acid catalyst is phosphoric acid; The concentration of the formaldehyde aqueous solution is 27-37%; The temperature of the condensation reaction is 40-90° C., and the reaction time is 0.5-7 hours.

3. The method for recovering and reusing the phosphoric acid catalyst for bisphenol F synthesis according to claim 1, characterized in that: In step (2), the separation temperature is 50 to 90° C., and the separation time is 0.5 to 3 h.

4. The method for recovering and reusing the phosphoric acid catalyst for bisphenol F synthesis according to claim 1, characterized in that: In step (3), the solvent is one or more mixed solvents selected from benzene, toluene, xylene, n-hexane, cyclohexane, and methyl isobutyl ketone; The volume ratio of the solvent to water is 0.5:1 to 5:1; the volume ratio of the oil phase I to the solvent is 0.2:1 to 2:1; The extraction water washing temperature is 40° C. to 90° C.; the number of multi-stage extractions is 2 to 6 times.

5. The method for recovering and reusing the phosphoric acid catalyst for bisphenol F synthesis according to claim 1, characterized in that: In step (4), the residual phosphoric acid content in the oil phase II is less than 5ppm to 50ppm.

6. The method for recovering and reusing the phosphoric acid catalyst for bisphenol F synthesis according to claim 1, characterized in that: In step (5), the phosphoric acid recovery rate of the recovered phosphoric acid is greater than 99.5% to 99.9%, and the phosphoric acid concentration is 70% to 86%.

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