Method for preparing epichlorohydrin by hydrogen peroxide method

Abstract

The invention relates to a method for preparing epichlorohydrin by a hydrogen peroxide method. The preparation method comprises the steps of pre-reaction, circular reaction, catalyst separation, backwashing, oil-water separation and the like. Some technical defects existing in the prior art are overcome, and the production process is simple, low in equipment investment, stable and reliable. Therefore, the production process disclosed by the invention has a very good industrial application prospect.

Description

[Technical field]

[0001] The present invention belongs to the technical field of organic chemical raw material production. More specifically, the present invention relates to a method for preparing epichlorohydrin by a hydrogen peroxide method. [Background technology]

[0002] Epichlorohydrin, as an important organic chemical raw material, is widely used in the production of epoxy resins, epichlorohydrin rubber, cation exchange resins and a variety of fine chemicals. With the growing market demand for downstream products such as epoxy resins, the production technology of epichlorohydrin has also continued to attract attention from the industry.

[0003] At present, the main methods for industrial production of epichlorohydrin include propylene high-temperature chlorination method, propylene acetate-allyl alcohol method and glycerol method. However, these methods all have certain problems in the production process. For example, although the propylene high-temperature chlorination method is mature in technology, the equipment is severely corroded, the energy consumption quota is high, and the sewage discharge is large, which does not meet the current green and environmentally friendly production requirements; although the propylene acetate-allyl alcohol method uses less raw materials chlorine and lime and has a higher yield, it has many reaction steps, relatively high equipment investment, and acetic acid is highly corrosive, which has high requirements for equipment materials; although the glycerol method is green and environmentally friendly, the cost of the raw material glycerol is high, and the technical difficulty lies in the selection of an efficient catalyst.

[0004] In recent years, in order to solve the above technical problems, researchers have begun to explore a new process for preparing epichlorohydrin by hydrogen peroxide. As an environmentally friendly oxidant, hydrogen peroxide has the advantages of mild reaction conditions, environmental friendliness, and easy separation of products. Using hydrogen peroxide as a raw material to prepare epichlorohydrin can not only reduce production costs, but also reduce environmental pollution, which is in line with the current development trend of green chemistry. Specifically, the process for preparing epichlorohydrin by hydrogen peroxide usually involves using 3-chloropropylene as a raw material and carrying out an epoxidation reaction with hydrogen peroxide as an oxidant under the action of a catalyst. In this reaction process, by controlling conditions such as reaction temperature, pressure, catalyst type and dosage, the reaction process can be optimized and the yield and selectivity of epichlorohydrin can be improved.

[0005] However, despite the many advantages of preparing epichlorohydrin by hydrogen peroxide, the process still has some technical bottlenecks, such as catalyst selection and stability, reaction condition optimization, product separation and purification, etc. Therefore, developing a new process for preparing epichlorohydrin by hydrogen peroxide with high efficiency, environmental protection and economy is of great significance for improving the production efficiency of epichlorohydrin, reducing production costs and reducing environmental pollution.

[0006] CN115894400B discloses a process for preparing epichlorohydrin by direct oxidation of chloropropylene in a liquid-solid circulating fluidized bed reactor, but the process device has a complex structure, is difficult to operate, and is not easy to achieve industrial production. The effective utilization rate of hydrogen peroxide is 96.0%, which is low. Excessive hydrogen peroxide is ineffectively decomposed, and the large amount of oxygen produced by decomposition brings great trouble to the process safety. CN110204512B discloses a process for catalytic production of epichlorohydrin using a phase transfer catalyst. The catalyst used in the process is a phosphotungstic heteropoly acid salt. This type of catalyst has high requirements for the production system, a large amount of catalyst, is difficult to recover, and has serious loss, which increases the production cost of epichlorohydrin.

[0007] Aiming at the technical defects of the prior art, the inventor has finally completed the present invention through a large number of experimental studies and analytical summaries based on the summary of the prior art. [Summary of the invention]

[0008] [Technical issues to be solved]

[0009] The object of the present invention is to provide a method for preparing epichlorohydrin by a hydrogen peroxide method.

[0010] [Technical solution]

[0011] The present invention is achieved through the following technical solutions.

[0012] The invention relates to a method for preparing epichlorohydrin by a hydrogen peroxide method.

[0013] The preparation steps of the preparation method are as follows:

[0014] A. Pre-reaction

[0015] Hydrogen peroxide, allyl chloride and solvent are added from one side of the top of the pre-reactor 1, and nitrogen is introduced from the same side of the top, and a catalyst is added from the opposite side of the top of the pre-reactor 1, and a pipeline for exhaust gas is installed on the top of the pre-reactor 1; hydrogen peroxide and allyl chloride react for 30 to 90 minutes at a temperature of 20 to 40° C. and under stirring in the presence of the catalyst to obtain a pre-reaction liquid;

[0016] B. Cyclic reaction

[0017] The pre-reaction liquid obtained in step A is sent from the bottom of the pre-reaction kettle 1 to the top of the circulating reaction kettle 3 through a pipeline by the pre-reaction liquid pump 2, and nitrogen is introduced from the top of the circulating reaction kettle 3, and a pipeline for discharging tail gas is installed on the top of the circulating reaction kettle 3; the pre-reaction liquid is reacted at a temperature of 20 to 40° C. and stirred for 60 to 120 minutes to obtain a mixture solution containing epichlorohydrin, allyl chloride, a catalyst, a solvent and water;

[0018] C. Catalyst separation

[0019] The mixed solution obtained in step B is discharged from the bottom of the circulating reactor 3, and is sent to the bottom of the ceramic membrane filter 5 by the circulating reaction pump 4, and filtered and separated by the ceramic membrane filter 5 to obtain a concentrated solution containing the catalyst and a clear solution without the catalyst; when the catalyst contained in the concentrated solution still has catalytic activity, the concentrated solution is returned to the top of the circulating reactor 3 through the A pipe port and the B pipe port of the membrane filter three-way switch 9 located at the top of the ceramic membrane filter 5 through the pipeline; when the catalyst contained in the concentrated solution has no catalytic activity, the concentrated solution containing the deactivated catalyst is discharged from the pipeline through the A pipe port and the C pipe port of the membrane filter three-way switch 9; the clear liquid is sent to the clear liquid storage tank 7 for storage through the pipeline located at the upper end of the side wall of the ceramic membrane filter 5 through the A pipe port and the B pipe port of the three-way switch 10 on the clear liquid storage tank, and the clear liquid contains epichlorohydrin, allyl chloride, solvent and water;

[0020] D. Backwash

[0021] When the filtration efficiency of the ceramic membrane filter 5 is reduced by less than 40%, under the condition of closing the three-way switch 10 on the clear liquid storage tank, the clear liquid in the clear liquid storage tank 7 is sent from the bottom of the clear liquid storage tank 7 through the A pipe port and the B pipe port of the lower three-way switch 11 of the clear liquid storage tank and the pipeline by the backwashing pump 6 to the lower part of the ceramic membrane filter 5, so that the clear liquid backwashes the ceramic membrane filter 5 until the filtration efficiency of the ceramic membrane filter 5 reaches more than 90%, and then the backwashing is stopped, and then the three-way switch 10 on the clear liquid storage tank is opened, and the backwashing liquid collected in the upper part of the ceramic membrane filter 5 is sent to the clear liquid storage tank 7 through the pipeline and the A pipe port and the B pipe port of the three-way switch 10 on the clear liquid storage tank;

[0022] E. Oil-water separation

[0023] The clear liquid obtained in step C is sent from the bottom of the clear liquid storage tank 7 through the A pipe port and the C pipe port of the three-way switch 11 under the clear liquid storage tank and the pipeline to the upper part of the liquid phase separator 8, and the water phase and the oil phase are separated under the condition of continuous feeding and discharging. The water phase is sent from the upper part of the liquid phase separator 8 to the light component refining process through the pipeline, and is refined by multi-stage vacuum distillation to obtain the unreacted allyl chloride and the solvent for recovery, and also to obtain the epichlorohydrin product. The oil phase is sent from the bottom of the liquid phase separator 8 to the heavy component refining process through the pipeline, and is refined by vacuum distillation after stripping to obtain the epichlorohydrin product.

[0024] According to a preferred embodiment of the present invention, in step A, the molar ratio of hydrogen peroxide to allyl chloride is 1:1-5; the molar ratio of hydrogen peroxide to solvent is 1:1-4; and the amount of catalyst used is 0.5%-5.0% based on the total weight of hydrogen peroxide and allyl chloride.

[0025] According to another preferred embodiment of the present invention, in step A, the solvent is one or more solvents selected from methanol, ethanol, n-propanol, isopropanol, acetone or acetonitrile.

[0026] According to another preferred embodiment of the present invention, in step A, the concentration of the hydrogen peroxide is 20% to 50% by weight of hydrogen peroxide.

[0027] According to another preferred embodiment of the present invention, in step A and step B, the flow rate of nitrogen is 10-1000 ml / min.

[0028] According to another preferred embodiment of the present invention, in step A, the catalyst is TS-1, TS-2 type titanium silicon molecular sieve or Ti-MCM-41, Ti-SBA-15 type mesoporous molecular sieve.

[0029] According to another preferred embodiment of the present invention, in step A and step B, the pre-reactor 1 and the circulation reactor 3 are a reactor formed by connecting an upper semicircular structure, a middle cylindrical structure and a lower conical structure.

[0030] According to another preferred embodiment of the present invention, in step C, the ceramic membrane filter 5 is a filter with a cylindrical barrel structure, and a tubular ceramic membrane filter medium with a pore size of 1 to 10 nm is filled in the barrel.

[0031] According to another preferred embodiment of the present invention, in step D, the clear liquid storage tank 7 is a vertical storage tank formed by connecting an upper circular structure, a middle cylindrical structure and a lower circular structure.

[0032] According to another preferred embodiment of the present invention, in step D, the liquid phase separator 8 is a vertical separation tank structure, which is composed of an elliptical head at the upper end, a cylindrical tank body structure in the middle and a U-shaped tube discharge port at the lower end.

[0033] The present invention will be described in more detail below.

[0034] The inventors have proposed an innovative process for preparing epichlorohydrin by hydrogen peroxide method, which achieves efficient, environmentally friendly and economical production of epichlorohydrin by optimizing the selection of catalysts and their stability, improving reaction conditions and perfecting product separation technology. This method not only has broad market application prospects, but also can provide strong technical support for the green development of related industries.

[0035] The present invention relates to a method for preparing epichlorohydrin by hydrogen peroxide method. The specific process flow of the preparation method is shown in the attached Figure 1 .

[0036] The preparation steps of the preparation method are as follows:

[0037] A. Pre-reaction

[0038] Hydrogen peroxide, allyl chloride and solvent are added from one side of the top of the pre-reactor 1, and nitrogen is introduced from the same side of the top, and a catalyst is added from the opposite side of the top of the pre-reactor 1, and a pipeline for exhaust gas is installed on the top of the pre-reactor 1; hydrogen peroxide and allyl chloride react for 30 to 90 minutes at a temperature of 20 to 40° C. and under stirring in the presence of the catalyst to obtain a pre-reaction liquid;

[0039] In the present invention, the main purpose of the pre-reaction step is to mix the hydrogen peroxide, propylene chloride reactants and the catalyst evenly to ensure that the reactants can carry out their oxidation reaction under optimized conditions; the main function of introducing nitrogen from the top of the pre-reaction kettle 1 is to inert the atmosphere in the pre-reaction kettle 1 to prevent the oxygen generated by the hydrogen peroxide from mixing with other organic vapors to form an explosive gas.

[0040] In this step, the molar ratio of hydrogen peroxide to allyl chloride is 1:1-5; the molar ratio of hydrogen peroxide to solvent is 1:1-4; and the amount of catalyst used is 0.5%-5.0% based on the total weight of hydrogen peroxide and allyl chloride.

[0041] The molar ratio of hydrogen peroxide to allyl chloride is 1:1-5; if the molar ratio of hydrogen peroxide to allyl chloride is greater than 1:1, more hydrogen peroxide will remain in the reaction solution, resulting in waste of hydrogen peroxide and a higher risk of subsequent product separation; if the molar ratio of hydrogen peroxide to allyl chloride is less than 1:5, the allyl chloride content in the reaction system is high, the hydrogen peroxide concentration is low, and the oxidation reaction is not thorough. Therefore, it is reasonable that the molar ratio of hydrogen peroxide to allyl chloride is 1:1-5, preferably 1:1.8-4.2, and more preferably 1:2.2-3.8.

[0042] The molar ratio of hydrogen peroxide to solvent is 1:1 to 4. If the molar ratio of hydrogen peroxide to solvent is less than 1:4, the concentration of hydrogen peroxide in the reaction system is low, and the oxidation reaction is not thorough, resulting in a waste of hydrogen peroxide; if the molar ratio of hydrogen peroxide to solvent is greater than 1:1, the amount of solvent used in the oxidation reaction is low, resulting in a slow reaction rate and affecting production efficiency. Therefore, the molar ratio of hydrogen peroxide to solvent is suitable to be 1:1 to 4, preferably 1:1.4 to 3.6, and more preferably 1:1.8 to 3.2.

[0043] The amount of catalyst used is 0.5% to 5.0% based on the total weight of hydrogen peroxide and allyl chloride. If the amount of catalyst used is higher than 5.0%, it will lead to ineffective decomposition of excessive hydrogen peroxide, affecting the effective utilization rate of hydrogen peroxide, and too much catalyst will easily cause clogging of the ceramic membrane filter, affecting production efficiency; if the amount of catalyst used is lower than 0.5%, it will lead to too long reaction time, increase subsequent reaction time, and increase production costs. Therefore, the amount of catalyst used is suitable to be 0.5% to 5%, preferably 1.0% to 4.5%, and more preferably 1.6% to 3.8%.

[0044] The concentration of hydrogen peroxide used in the present invention is 20% to 50% based on the weight of hydrogen peroxide. If the concentration is higher than 50%, the concentration of hydrogen peroxide is too high, which increases production risks and reduces the effective utilization rate of hydrogen peroxide; if the concentration of hydrogen peroxide is lower than 20%, the oxidation reaction proceeds slowly and introduces a large amount of wastewater, increasing production costs. Therefore, it is reasonable for the concentration of hydrogen peroxide to be 20% to 50%, preferably 27% to 35%.

[0045] The catalyst used in the present invention is TS-1, TS-2 type titanium silicon molecular sieve or Ti-MCM-41, Ti-SBA-15 type mesoporous molecular sieve, which are all products currently sold on the market, such as the titanium silicon molecular sieve product sold by Tianjin Nanhua Catalyst Co., Ltd. under the trade name NKF-8 (TS-1) zeolite molecular sieve, the titanium silicon molecular sieve product sold by Zhuoran Environmental Protection Technology Co., Ltd. under the trade name TS-2 molecular sieve, and the mesoporous molecular sieve sold by Dalian Zeer Catalytic Materials Co., Ltd. under the trade names of Ti-MCM-41 molecular sieve catalyst and Ti-SBA-15 molecular sieve catalyst.

[0046] The solvent used in this step is one or more solvents selected from methanol, ethanol, n-propanol, isopropanol, acetone or acetonitrile, which are all products currently sold on the market, such as the product sold under the trade name of isopropanol by Suzhou Haibai Chemical Co., Ltd., the product sold under the trade name of n-propanol by Shandong Aowei Chemical Co., Ltd., the product sold under the trade name of ethanol by Jining Bocheng Chemical Co., Ltd., the product sold under the trade name of n-butanol by Shanghai McLean Biochemical Technology Co., Ltd., the product sold under the trade name of methanol by Sinopharm Chemical Reagent Co., Ltd., and the product sold under the trade name of acetone by Sinopharm Chemical Reagent Co., Ltd.

[0047] The flow rate of nitrogen used in this step is 10 to 1000 ml / min. If the flow rate of nitrogen is lower than 10 ml / min, the oxygen generated by the ineffective decomposition of hydrogen peroxide in the system cannot be removed from the system in time, and an explosive mixture is easily formed in the system; if the flow rate of nitrogen is higher than 1000 ml / min, the gas flow rate is too large, which is easy to cause excessive loss of allyl chloride; therefore, the flow rate of nitrogen is appropriately 10 to 1000 ml / min, preferably 100 to 800 ml / min, and more preferably 200 to 600 ml / min;

[0048] In this step, hydrogen peroxide and allyl chloride react with a catalyst at a temperature of 20 to 40° C. and under stirring for 30 to 90 minutes to obtain a pre-reaction solution; when the reaction time is within the range, if the reaction temperature is lower than 20° C., the reaction rate is slow and the hydrogen peroxide cannot react to a concentration below the appropriate concentration; if the reaction temperature is higher than 40° C., the hydrogen peroxide is ineffectively decomposed violently and side reactions are likely to occur, thereby reducing the product yield; therefore, a reaction temperature of 20 to 40° C. is appropriate, preferably 26 to 34° C.; when the reaction temperature is within the range, if the reaction time is shorter than 30 minutes, the reaction time is too short and the hydrogen peroxide cannot react to a concentration below the appropriate concentration; if the reaction time is longer than 90 minutes, this step takes a long time and cannot effectively shorten the reaction time of the next step, thereby increasing the production cost; therefore, a reaction time of 30 to 90 minutes is desirable, preferably 40 to 80 minutes, and more preferably 48 to 72 minutes.

[0049] The pre-reactor 1 used in the present invention is a reactor formed by connecting an upper semicircular structure, a middle cylindrical structure and a lower conical structure. An agitator is arranged at the center of the upper semicircular structure in an overlapping manner with the central axis of the cylindrical barrel, and material inlets and outlets are arranged on both sides of the center of the upper semicircular structure, and a material outlet is arranged at the top of the conical lower end. The structure of the circulating reactor 3 used in the subsequent steps is basically the same, so it will not be repeated below.

[0050] The equipments such as the pre-reactor 1 and the circulating reactor 3 used in the present invention are all products currently sold on the market. For example, the pre-reactor 1 and the circulating reactor 3 are both products sold by Jinxi Chemical Machinery Group Co., Ltd. under the trade name of reactor.

[0051] B. Cyclic reaction

[0052] The pre-reaction liquid obtained in step A is sent from the bottom of the pre-reaction kettle 1 to the top of the circulating reaction kettle 3 through a pipeline by the pre-reaction liquid pump 2, and nitrogen is introduced from the top of the circulating reaction kettle 3, and a pipeline for discharging tail gas is installed on the top of the circulating reaction kettle 3; the pre-reaction liquid is reacted at a temperature of 20 to 40° C. and stirred for 60 to 120 minutes to obtain a mixture solution containing epichlorohydrin, allyl chloride, a catalyst, a solvent and water;

[0053] In the present invention, the main purpose of the circulation reaction is to react the residual hydrogen peroxide in the mixture solution obtained in step A as completely as possible, reduce the risk of subsequent wastewater treatment, recover the catalyst, and achieve solid-liquid separation. The main purpose of introducing nitrogen from the top of the circulation reactor 3 is to inert the atmosphere in the circulation reactor 3 to prevent the oxygen generated by the hydrogen peroxide from mixing with other steam to form an explosive gas.

[0054] In this step, the cyclic reaction is carried out at a temperature of 20 to 40 ° C for 60 to 120 minutes. When the cyclic reaction time is within the range, if the cyclic reaction temperature is higher than 40 ° C, it may cause a large amount of decomposition of hydrogen peroxide, reduce the utilization rate of hydrogen peroxide, and release heat seriously, increasing production risks; if the cyclic reaction temperature is lower than 20 ° C, the cyclic reaction will be slowed down, the reaction time will be greatly extended, and the production cost will be increased. Therefore, it is appropriate for the cyclic reaction temperature to be 20 to 40 ° C, preferably 26 to 34 ° C. When the cyclic reaction time is within the range, if the cyclic reaction time is longer than 120 minutes, it may lead to the formation of ether by-products, increase the difficulty of subsequent product separation, and reduce product purity; if the cyclic reaction time is shorter than 60 minutes, hydrogen peroxide is not completely reacted, resulting in waste of hydrogen peroxide, and also increasing the difficulty of subsequent wastewater treatment. Therefore, it is reasonable for the cyclic reaction time to be 60 to 120 minutes, preferably 60 to 120 minutes, and more preferably 72 to 105 minutes.

[0055] The nitrogen flow rate of this step is 10 to 1000 ml / min. If the nitrogen flow rate is lower than 10 ml / min, the oxygen generated by the ineffective decomposition of hydrogen peroxide in the system cannot be removed from the system in time, and an explosive mixture is easily formed in the system; if the nitrogen flow rate is higher than 1000 ml / min, the gas flow rate is too large, which is easy to cause excessive loss of allyl chloride; therefore, a nitrogen flow rate of 10 to 1000 ml / min is appropriate, preferably 100 to 800 ml / min, and more preferably 200 to 600 ml / min;

[0056] According to conventional gas chromatography internal standard method analysis, the mixture solution contains 20-30% epichlorohydrin and 15-25% allyl chloride by weight.

[0057] The pre-reaction liquid pump 2 used in the present invention is, for example, a product sold by Shanghai Kaishi Pump Industry Group Co., Ltd. under the trade name KSW series horizontal centrifugal pump.

[0058] C. Catalyst separation

[0059] The mixed solution obtained in step B is discharged from the bottom of the circulating reactor 3, and is sent to the bottom of the ceramic membrane filter 5 by the circulating reaction pump 4, and filtered and separated by the ceramic membrane filter 5 to obtain a concentrated solution containing the catalyst and a clear solution without the catalyst; when the catalyst contained in the concentrated solution still has catalytic activity, the concentrated solution is returned to the top of the circulating reactor 3 through the A pipe port and the B pipe port of the membrane filter three-way switch 9 located at the top of the ceramic membrane filter 5 through the pipeline; when the catalyst contained in the concentrated solution has no catalytic activity, the concentrated solution containing the deactivated catalyst is discharged from the pipeline through the A pipe port and the C pipe port of the membrane filter three-way switch 9; the clear liquid is sent to the clear liquid storage tank 7 for storage through the pipeline located at the upper end of the side wall of the ceramic membrane filter 5 through the A pipe port and the B pipe port of the three-way switch 10 on the clear liquid storage tank, and the clear liquid contains epichlorohydrin, allyl chloride, solvent and water;

[0060] In the present invention, the catalyst separation step is mainly intended to separate the mixture solution containing epichlorohydrin, allyl chloride, catalyst, solvent and water obtained in step B into solid-liquid separation.

[0061] The circulating reaction pump 4 used in the present invention is a horizontal centrifugal pump, which is a product currently sold on the market, for example, a product sold by Shanghai Kaishi Pump Industry Group Co., Ltd. under the trade name KSW series horizontal centrifugal pumps.

[0062] The ceramic membrane filter 5 used in the present invention is a filter with a cylindrical barrel structure, in which a filter medium of a tubular ceramic membrane with a pore size of 1 to 10 nm is filled. The ceramic membrane is a precision ceramic filter material with a porous structure made of materials such as aluminum oxide, titanium oxide, and zirconium oxide through high-temperature sintering. The ceramic membrane used in the present invention is a product currently sold on the market, such as the product sold by Zibo Dongqiang Membrane Technology Co., Ltd. under the trade name DQCM series tubular ceramic membrane.

[0063] The ratio of diameter to length of the ceramic membrane filter 5 used in the present invention is 1:3-8. It is a product currently sold on the market, such as the product sold by Zibo Dongqiang Membrane Technology Co., Ltd. under the trade name of ceramic filter element filter.

[0064] The clear liquid storage tank 7 used in the present invention is a vertical storage tank formed by connecting an upper circular structure, a middle cylindrical structure and a lower circular structure. The diameters of the upper circular structure and the lower circular structure are the same as the diameter of the middle cylindrical structure. The ratio of the diameter to the height of the clear liquid storage tank 7 is 1:3 to 5. The clear liquid storage tank 7 used in the present invention is a product currently sold on the market, such as a product sold by Wuxi Hengnuo Chemical Equipment Manufacturing Co., Ltd. under the trade name of liquid storage tank.

[0065] The membrane filter three-way switch 9 used in the present invention is a three-way switch having three mutually perpendicular pipe openings, which can control the flow direction of the reactants. The membrane filter three-way switch used in the present invention is a product currently sold on the market, such as a product sold by Shanghai Kangwei Automatic Valve Co., Ltd. under the trade name of a ball three-way shunt valve. The upper three-way switch 10 of the clear liquid storage tank and the lower three-way switch 11 of the clear liquid storage tank used later are the same as the membrane filter three-way switch 9, so they are not described in detail below.

[0066] The circulating reaction pump 4 used in the present invention is a product sold by Shanghai Kaishi Pump Industry Group Co., Ltd. under the trade name KSW series horizontal centrifugal pump.

[0067] According to conventional gas chromatography internal standard method analysis, the clear liquid obtained in this step contains 20-30% epichlorohydrin and 15-25% allyl chloride by weight.

[0068] D. Backwash

[0069] When the filtration efficiency of the ceramic membrane filter 5 is reduced by less than 40%, under the condition of closing the three-way switch 10 on the clear liquid storage tank, the clear liquid in the clear liquid storage tank 7 is sent from the bottom of the clear liquid storage tank 7 through the A pipe port and the B pipe port of the lower three-way switch 11 of the clear liquid storage tank and the pipeline by the backwashing pump 6 to the lower part of the ceramic membrane filter 5, so that the clear liquid backwashes the ceramic membrane filter 5 until the filtration efficiency of the ceramic membrane filter 5 reaches more than 90%, and then the backwashing is stopped, and then the three-way switch 10 on the clear liquid storage tank is opened, and the backwashing liquid collected in the upper part of the ceramic membrane filter 5 is sent to the clear liquid storage tank 7 through the pipeline and the A pipe port and the B pipe port of the three-way switch 10 on the clear liquid storage tank;

[0070] In the present invention, the main purpose of this backwashing step is to improve the separation efficiency of the catalyst and the reaction liquid and to prevent the catalyst particles from clogging the ceramic membrane filter 5, thereby causing an increase in the pressure of the entire reaction system.

[0071] In the present invention, the filtration efficiency of the ceramic membrane filter 5 should be understood to be calculated by the amount of clear liquid filtered out by the ceramic filter in the same filtration time.

[0072] The clear liquid storage tank 7 used in the present invention is, for example, a product sold by Wuxi Hengnuo Chemical Equipment Manufacturing Co., Ltd. under the trade name of liquid storage tank, and the backwash pump 6 is a product sold by Shanghai Kaishi Pump Industry Group Co., Ltd. under the trade name of KSW series horizontal centrifugal pump.

[0073] E. Oil-water separation

[0074] The clear liquid obtained in step C is sent from the bottom of the clear liquid storage tank 7 through the A pipe port and the C pipe port of the three-way switch 11 under the clear liquid storage tank and the pipeline to the upper part of the liquid phase separator 8, and the water phase and the oil phase are separated under the condition of continuous feeding and discharging. The water phase is sent from the upper part of the liquid phase separator 8 to the light component refining process through the pipeline, and is refined by multi-stage vacuum distillation to obtain the unreacted allyl chloride and the solvent for recovery, and also to obtain the epichlorohydrin product. The oil phase is sent from the bottom of the liquid phase separator 8 to the heavy component refining process through the pipeline, and is refined by vacuum distillation after stripping to obtain the epichlorohydrin product.

[0075] In this step, the main purpose of the oil-water separation step is to separate the oil phase and the water phase of the clear liquid product obtained in step C to facilitate subsequent product purification.

[0076] The liquid phase separator 8 is a vertical separation tank structure, which is connected by an elliptical head at the upper end, a cylindrical tank structure in the middle, and a U-shaped pipe outlet at the lower end. Its feed port is arranged in the middle and upper part of the cylindrical tank body, the water phase outlet is arranged in the upper part of the other side of the tank body, and the oil phase outlet is arranged at the bottom of the tank body. The liquid phase separator 8 used in the present invention is a product currently sold on the market, such as a product sold by Wuxi Lebiao Filtration Equipment Co., Ltd. under the trade name of oil-water coalescing separator.

[0077] According to conventional gas chromatography internal standard method analysis, the crude oil phase product prepared by the present invention contains 10-40% epichlorohydrin, 10-40% allyl chloride, 10-40% solvent and 0.1-1.0% water by weight; the crude water phase product prepared by the present invention contains 0.5-2.0% epichlorohydrin, 0.2-1.0% allyl chloride, 10-50% solvent, 10-50% water by weight.

[0078] The hydrogen peroxide conversion rate and the hydrogen peroxide effective utilization rate of the preparation method of the present invention are calculated according to the following formulas:

[0079] Hydrogen peroxide conversion rate = hydrogen peroxide input molar amount - hydrogen peroxide remaining molar amount / hydrogen peroxide input molar amount x 100%;

[0080] Effective utilization rate of hydrogen peroxide = molar amount of epichlorohydrin produced / molar amount of hydrogen peroxide consumed x 100%.

[0081] [Beneficial Effects]

[0082] The beneficial effects of the present invention are: the preparation method of the present invention can realize the preparation of epichlorohydrin from 3-chloropropylene through hydrogen peroxide oxidation reaction; the present invention solves some technical defects existing in the prior art, and the production process is simple, stable and reliable. Therefore, the production method of the present invention has very good industrial application prospects.

Brief Description of the Drawings

[0083] Figure 1 This is a process flow chart of producing epichlorohydrin from 3-chloropropylene of the present invention;

[0084] In the figure:

[0085] 1-pre-reaction kettle; 2-first pre-reaction liquid pump; 3-circulation reaction kettle; 4-second circulation reaction pump; 5-ceramic membrane filter; 6-backwash pump; 7-clear liquid storage tank; 8-liquid phase separator; 9-membrane filter three-way switch; 10-upper three-way switch of clear liquid storage tank; 11-lower three-way switch of clear liquid storage tank. [Specific implementation method]

[0086] The present invention will be better understood through the following examples.

[0087] Example 1: Preparation of epichlorohydrin by hydrogen peroxide method of the present invention

[0088] The implementation steps of this embodiment are as follows:

[0089] A. Pre-reaction

[0090] According to the molar ratio of hydrogen peroxide to allyl chloride of 1:3 and the molar ratio of hydrogen peroxide to solvent of 1:2; hydrogen peroxide, allyl chloride and ethanol solvent with a concentration of 40% by weight of hydrogen peroxide were added to one side of the top of a pre-reactor 1 sold by Jinxi Chemical Machinery Group Co., Ltd. under the trade name Reactor, and nitrogen was introduced at a flow rate of 350 ml / min from the same side of the top, and TS-1 titanium silicon molecular sieve catalyst sold by Tianjin Nanhua Catalyst Co., Ltd. was added from the opposite side of the top of the pre-reactor 1 at a concentration of 3.5% by total weight of hydrogen peroxide and allyl chloride, and a pipeline for exhausting exhaust gas was installed on the top of the pre-reactor 1; hydrogen peroxide and allyl chloride were reacted at a temperature of 40°C and stirred for 30 minutes in the presence of the catalyst to obtain a pre-reaction liquid;

[0091] B. Cyclic reaction

[0092] The pre-reaction liquid obtained in step A is sent from the bottom of the pre-reaction kettle 1 through a pipeline by a pre-reaction liquid pump 2 sold by Shanghai Kaishi Pump Industry Group Co., Ltd. under the trade name KSW series horizontal centrifugal pump to the top of the circulating reactor 3 sold by Jinxi Chemical Machinery Group Co., Ltd. under the trade name reactor, and nitrogen is introduced from the top of the circulating reactor 3 at a flow rate of 350 ml / min, and a pipeline for discharging tail gas is installed at the top of the circulating reactor 3; the pre-reaction liquid is reacted at a temperature of 40° C. and stirred for 60 minutes to obtain a mixture solution containing epichlorohydrin, allyl chloride, a catalyst, a solvent and water;

[0093] C. Catalyst separation

[0094] The mixed solution obtained in step B is discharged from the bottom of the circulating reactor 3, and is sent to the bottom of a ceramic membrane filter 5 filled with a tubular ceramic membrane filter medium with a pore size of 1 to 10 nm by a circulating reaction pump 4 sold by Shanghai Kaishi Pump Industry Group Co., Ltd. under the trade name KSW series horizontal centrifugal pump, and filtered and separated by the ceramic membrane filter 5 to obtain a concentrated solution containing a catalyst and a clear solution without a catalyst; the catalyst contained in the concentrated solution also has catalytic activity, and the concentrated solution is returned to the top of the circulating reactor 3 through the A pipe port and the B pipe port of the membrane filter three-way switch 9 located at the top of the ceramic membrane filter 5 through the pipeline; the clear liquid is sent to the clear liquid storage tank 7 for storage through the A pipe port and the B pipe port of the three-way switch 10 on the clear liquid storage tank from the pipeline located at the upper end of the side wall of the ceramic membrane filter 5. The clear liquid contains epichlorohydrin, allyl chloride, solvent and water;

[0095] D. Backwash

[0096] When the filtration efficiency of the ceramic membrane filter 5 is reduced by less than 40%, under the condition of closing the three-way switch 10 on the clear liquid storage tank, the clear liquid in the clear liquid storage tank 7 sold by Wuxi Hengnuo Chemical Equipment Manufacturing Co., Ltd. under the trade name of liquid storage tank is sent from the bottom of the clear liquid storage tank 7 through the A pipe port and the B pipe port of the three-way switch 11 under the clear liquid storage tank and the pipeline by the backwash pump 6 sold by Shanghai Kaishi Pump Industry Group Co., Ltd. under the trade name of KSW series horizontal centrifugal pump to the lower part of the ceramic membrane filter 5, so that the clear liquid backwashes the ceramic membrane filter 5 until the filtration efficiency of the ceramic membrane filter 5 reaches 90.2% and the backwashing is stopped. Then the three-way switch 10 on the clear liquid storage tank is opened, and the backwashing liquid collected in the upper part of the ceramic membrane filter 5 is sent to the clear liquid storage tank 7 through the pipeline and the A pipe port and the B pipe port of the three-way switch 10 on the clear liquid storage tank;

[0097] E. Oil-water separation

[0098] The clear liquid obtained in step C is sent from the bottom of the clear liquid storage tank 7 through the A pipe port and the C pipe port of the three-way switch 11 under the clear liquid storage tank and the pipeline to the upper part of the liquid phase separator 8, and the water phase and the oil phase are separated under the condition of continuous feeding and discharging. The water phase is sent to the light component refining process through a pipeline from the upper part of the liquid phase separator 8 sold by Wuxi Lebiao Filtration Equipment Co., Ltd. under the trade name of oil-water coalescing separator, and is refined by a multi-stage vacuum distillation method to obtain a product containing unreacted allyl chloride and the solvent for recovery, and also to obtain an epichlorohydrin product; the oil phase is sent from the bottom of the liquid phase separator 8 through a pipeline to the heavy component refining process, and is refined by a vacuum distillation method after stripping to obtain the epichlorohydrin product.

[0099] The results of this embodiment are shown in Table 1 according to the method described in the specification of this application.

[0100] Example 2: Preparation of epichlorohydrin by hydrogen peroxide method of the present invention

[0101] The implementation steps of this embodiment are as follows:

[0102] A. Pre-reaction

[0103] According to the molar ratio of hydrogen peroxide to allyl chloride of 1:1 and the molar ratio of hydrogen peroxide to solvent of 1:1; hydrogen peroxide, allyl chloride and n-propanol solvent with a concentration of 20% by weight of hydrogen peroxide are added to one side of the top of a pre-reactor 1 sold by Jinxi Chemical Machinery Group Co., Ltd. under the trade name Reactor, and nitrogen is introduced at a flow rate of 10 ml / min from the same side of the top, and TS-2 titanium silicon molecular sieve catalyst sold by Zhuoran Environmental Protection Technology Co., Ltd. is added from the opposite side of the top of the pre-reactor 1 at a concentration of 0.5% by total weight of hydrogen peroxide and allyl chloride, and a pipeline for exhausting exhaust gas is installed on the top of the pre-reactor 1; hydrogen peroxide and allyl chloride react at a temperature of 28° C. and under stirring for 70 minutes in the presence of the catalyst to obtain a pre-reaction liquid;

[0104] B. Cyclic reaction

[0105] The pre-reaction liquid obtained in step A is sent from the bottom of the pre-reaction kettle 1 through a pipeline by a pre-reaction liquid pump 2 sold by Shanghai Kaishi Pump Industry Group Co., Ltd. under the trade name KSW series horizontal centrifugal pump to the top of the circulating reactor 3 sold by Jinxi Chemical Machinery Group Co., Ltd. under the trade name reactor, and nitrogen is introduced from the top of the circulating reactor 3 at a flow rate of 10 ml / min, and a pipeline for discharging tail gas is installed at the top of the circulating reactor 3; the pre-reaction liquid is reacted at a temperature of 28° C. and stirred for 100 minutes to obtain a mixture solution containing epichlorohydrin, allyl chloride, a catalyst, a solvent and water;

[0106] C. Catalyst separation

[0107] The mixture solution obtained in step B is discharged from the bottom of the circulating reactor 3, and is sent to the bottom of a ceramic membrane filter 5 filled with a tubular ceramic membrane filter medium with a pore size of 1 to 10 nm by a circulating reaction pump 4 sold by Shanghai Kaishi Pump Industry Group Co., Ltd. under the trade name KSW series horizontal centrifugal pump, and filtered and separated by the ceramic membrane filter 5 to obtain a concentrated solution containing a catalyst and a clear solution without a catalyst; the catalyst contained in the concentrated solution has no catalytic activity, and the concentrated solution containing the deactivated catalyst is discharged from the pipeline through the A and C pipe ports of the membrane filter three-way switch 9; the clear liquid is sent to the clear liquid storage tank 7 for storage through the pipe located at the upper end of the side wall of the ceramic membrane filter 5 through the A and B pipe ports of the three-way switch 10 on the clear liquid storage tank, and the clear liquid contains epichlorohydrin, allyl chloride, solvent and water;

[0108] D. Backwash

[0109] When the filtration efficiency of the ceramic membrane filter 5 is reduced by less than 40%, under the condition of closing the three-way switch 10 on the clear liquid storage tank, the clear liquid in the clear liquid storage tank 7 sold by Wuxi Hengnuo Chemical Equipment Manufacturing Co., Ltd. under the trade name of liquid storage tank is sent from the bottom of the clear liquid storage tank 7 through the A pipe port and the B pipe port of the three-way switch 11 under the clear liquid storage tank and the pipeline by the backwash pump 6 sold by Shanghai Kaishi Pump Industry Group Co., Ltd. under the trade name of KSW series horizontal centrifugal pump to the lower part of the ceramic membrane filter 5, so that the clear liquid backwashes the ceramic membrane filter 5 until the filtration efficiency of the ceramic membrane filter 5 reaches 90.5%. The backwashing is stopped, and then the three-way switch 10 on the clear liquid storage tank is opened, and the backwashing liquid collected in the upper part of the ceramic membrane filter 5 is sent to the clear liquid storage tank 7 through the pipeline and the A pipe port and the B pipe port of the three-way switch 10 on the clear liquid storage tank;

[0110] E. Oil-water separation

[0111] The clear liquid obtained in step C is sent from the bottom of the clear liquid storage tank 7 through the A pipe port and the C pipe port of the three-way switch 11 under the clear liquid storage tank and the pipeline to the upper part of the liquid phase separator 8, and the water phase and the oil phase are separated under the condition of continuous feeding and discharging. The water phase is sent to the light component refining process through a pipeline from the upper part of the liquid phase separator 8 sold by Wuxi Lebiao Filtration Equipment Co., Ltd. under the trade name of oil-water coalescing separator, and is refined by a multi-stage vacuum distillation method to obtain a product containing unreacted allyl chloride and the solvent for recovery, and also to obtain an epichlorohydrin product; the oil phase is sent from the bottom of the liquid phase separator 8 through a pipeline to the heavy component refining process, and is refined by a vacuum distillation method after stripping to obtain the epichlorohydrin product.

[0112] The results of this embodiment are shown in Table 1 according to the method described in the specification of this application.

[0113] Example 3: Preparation of epichlorohydrin by hydrogen peroxide method of the present invention

[0114] The implementation steps of this embodiment are as follows:

[0115] A. Pre-reaction

[0116] According to the molar ratio of hydrogen peroxide to allyl chloride of 1:5 and the molar ratio of hydrogen peroxide to solvent of 1:3; hydrogen peroxide, allyl chloride and isopropanol solvent with a concentration of 30% by weight of hydrogen peroxide are added to one side of the top of a pre-reactor 1 sold by Jinxi Chemical Machinery Group Co., Ltd. under the trade name Reactor, and nitrogen is introduced at a flow rate of 1000 ml / min from the same side of the top, and Ti-MCM-41 type mesoporous molecular sieve catalyst sold by Dalian Zeer Catalytic Materials Co., Ltd. is added from the opposite side of the top of the pre-reactor 1 according to 5.0% of the total weight of hydrogen peroxide and allyl chloride, and a pipeline for exhausting exhaust gas is installed on the top of the pre-reactor 1; hydrogen peroxide and allyl chloride react at a temperature of 20°C and under stirring for 90 minutes in the presence of the catalyst to obtain a pre-reaction liquid;

[0117] B. Cyclic reaction

[0118] The pre-reaction liquid obtained in step A is sent from the bottom of the pre-reaction kettle 1 through a pipeline by a pre-reaction liquid pump 2 sold by Shanghai Kaishi Pump Industry Group Co., Ltd. under the trade name KSW series horizontal centrifugal pump to the top of the circulating reactor 3 sold by Jinxi Chemical Machinery Group Co., Ltd. under the trade name reactor, and nitrogen is introduced from the top of the circulating reactor 3 at a flow rate of 700 ml / min, and a pipeline for discharging tail gas is installed at the top of the circulating reactor 3; the pre-reaction liquid is reacted at a temperature of 20° C. and stirred for 120 minutes to obtain a mixture solution containing epichlorohydrin, allyl chloride, a catalyst, a solvent and water;

[0119] C. Catalyst separation

[0120] The mixed solution obtained in step B is discharged from the bottom of the circulating reactor 3, and is sent to the bottom of a ceramic membrane filter 5 filled with a tubular ceramic membrane filter medium with a pore size of 1 to 10 nm by a circulating reaction pump 4 sold by Shanghai Kaishi Pump Industry Group Co., Ltd. under the trade name KSW series horizontal centrifugal pump, and filtered and separated by the ceramic membrane filter 5 to obtain a concentrated solution containing a catalyst and a clear solution without a catalyst; the catalyst contained in the concentrated solution also has catalytic activity, and the concentrated solution is returned to the top of the circulating reactor 3 through the A pipe port and the B pipe port of the membrane filter three-way switch 9 located at the top of the ceramic membrane filter 5 through the pipeline; the clear liquid is sent to the clear liquid storage tank 7 for storage through the A pipe port and the B pipe port of the three-way switch 10 on the clear liquid storage tank from the pipeline located at the upper end of the side wall of the ceramic membrane filter 5. The clear liquid contains epichlorohydrin, allyl chloride, solvent and water;

[0121] D. Backwash

[0122] When the filtration efficiency of the ceramic membrane filter 5 is reduced by less than 40%, under the condition of closing the three-way switch 10 on the clear liquid storage tank, the clear liquid in the clear liquid storage tank 7 sold by Wuxi Hengnuo Chemical Equipment Manufacturing Co., Ltd. under the trade name of liquid storage tank is sent from the bottom of the clear liquid storage tank 7 through the A pipe port and the B pipe port of the three-way switch 11 under the clear liquid storage tank and the pipeline by the backwash pump 6 sold by Shanghai Kaishi Pump Industry Group Co., Ltd. under the trade name of KSW series horizontal centrifugal pump to the lower part of the ceramic membrane filter 5, so that the clear liquid backwashes the ceramic membrane filter 5 until the filtration efficiency of the ceramic membrane filter 5 reaches 90.2543% and the backwashing is stopped, and then the three-way switch 10 on the clear liquid storage tank is opened, and the backwashing liquid collected in the upper part of the ceramic membrane filter 5 is sent to the clear liquid storage tank 7 through the pipeline and the A pipe port and the B pipe port of the three-way switch 10 on the clear liquid storage tank;

[0123] E. Oil-water separation

[0124] The clear liquid obtained in step C is sent from the bottom of the clear liquid storage tank 7 through the A pipe port and the C pipe port of the three-way switch 11 under the clear liquid storage tank and the pipeline to the upper part of the liquid phase separator 8, and the water phase and the oil phase are separated under the condition of continuous feeding and discharging. The water phase is sent to the light component refining process through a pipeline from the upper part of the liquid phase separator 8 sold by Wuxi Lebiao Filtration Equipment Co., Ltd. under the trade name of oil-water coalescing separator, and is refined by a multi-stage vacuum distillation method to obtain a product containing unreacted allyl chloride and the solvent for recovery, and also to obtain an epichlorohydrin product; the oil phase is sent from the bottom of the liquid phase separator 8 through a pipeline to the heavy component refining process, and is refined by a vacuum distillation method after stripping to obtain the epichlorohydrin product.

[0125] The results of this embodiment are shown in Table 1 according to the method described in the specification of this application.

[0126] Example 4: Preparation of epichlorohydrin by hydrogen peroxide method of the present invention

[0127] The implementation steps of this embodiment are as follows:

[0128] A. Pre-reaction

[0129] According to the molar ratio of hydrogen peroxide to allyl chloride of 1:2 and the molar ratio of hydrogen peroxide to solvent of 1:4; hydrogen peroxide, allyl chloride and acetone solvent with a concentration of 50% by weight of hydrogen peroxide are added to one side of the top of the pre-reactor 1 sold by Jinxi Chemical Machinery Group Co., Ltd. under the trade name Reactor, and nitrogen is introduced at a flow rate of 700 ml / min from the same side of the top, and Ti-SBA-15 type mesoporous molecular sieve catalyst sold by Dalian Zeer Catalytic Materials Co., Ltd. is added from the opposite side of the top of the pre-reactor 1 according to 2.0% of the total weight of hydrogen peroxide and allyl chloride, and a pipeline for exhausting exhaust gas is installed on the top of the pre-reactor 1; hydrogen peroxide and allyl chloride are reacted at a temperature of 34°C and under stirring for 50 minutes in the presence of the catalyst to obtain a pre-reaction liquid;

[0130] B. Cyclic reaction

[0131] The pre-reaction liquid obtained in step A is sent from the bottom of the pre-reaction kettle 1 through a pipeline by a pre-reaction liquid pump 2 sold by Shanghai Kaishi Pump Industry Group Co., Ltd. under the trade name KSW series horizontal centrifugal pump to the top of the circulating reactor 3 sold by Jinxi Chemical Machinery Group Co., Ltd. under the trade name reactor, and nitrogen is introduced from the top of the circulating reactor 3 at a flow rate of 1000 ml / min, and a pipeline for discharging tail gas is installed at the top of the circulating reactor 3; the pre-reaction liquid is reacted at a temperature of 34° C. and stirred for 80 minutes to obtain a mixture solution containing epichlorohydrin, allyl chloride, a catalyst, a solvent and water;

[0132] C. Catalyst separation

[0133] The mixture solution obtained in step B is discharged from the bottom of the circulating reactor 3, and is sent to the bottom of a ceramic membrane filter 5 filled with a tubular ceramic membrane filter medium with a pore size of 1 to 10 nm by a circulating reaction pump 4 sold by Shanghai Kaishi Pump Industry Group Co., Ltd. under the trade name KSW series horizontal centrifugal pump, and filtered and separated by the ceramic membrane filter 5 to obtain a concentrated solution containing a catalyst and a clear solution without a catalyst; the catalyst contained in the concentrated solution has no catalytic activity, and the concentrated solution containing the deactivated catalyst is discharged from the pipeline through the A and C pipe ports of the membrane filter three-way switch 9; the clear liquid is sent to the clear liquid storage tank 7 for storage through the pipe located at the upper end of the side wall of the ceramic membrane filter 5 through the A and B pipe ports of the three-way switch 10 on the clear liquid storage tank, and the clear liquid contains epichlorohydrin, allyl chloride, solvent and water;

[0134] D. Backwash

[0135] When the filtration efficiency of the ceramic membrane filter 5 is reduced by less than 40%, under the condition of closing the three-way switch 10 on the clear liquid storage tank, the clear liquid in the clear liquid storage tank 7 sold by Wuxi Hengnuo Chemical Equipment Manufacturing Co., Ltd. under the trade name of liquid storage tank is sent from the bottom of the clear liquid storage tank 7 through the A pipe port and the B pipe port of the three-way switch 11 under the clear liquid storage tank and the pipeline by the backwash pump 6 sold by Shanghai Kaishi Pump Industry Group Co., Ltd. under the trade name of KSW series horizontal centrifugal pump to the lower part of the ceramic membrane filter 5, so that the clear liquid backwashes the ceramic membrane filter 5 until the filtration efficiency of the ceramic membrane filter 5 reaches 90% and the backwashing is stopped, and then the three-way switch 10 on the clear liquid storage tank is opened, and the backwashing liquid collected in the upper part of the ceramic membrane filter 5 is sent to the clear liquid storage tank 7 through the pipeline and the A pipe port and the B pipe port of the three-way switch 10 on the clear liquid storage tank;

[0136] E. Oil-water separation

[0137] The clear liquid obtained in step C is sent from the bottom of the clear liquid storage tank 7 through the A pipe port and the C pipe port of the three-way switch 11 under the clear liquid storage tank and the pipeline to the upper part of the liquid phase separator 8, and the water phase and the oil phase are separated under the condition of continuous feeding and discharging. The water phase is sent to the light component refining process through a pipeline from the upper part of the liquid phase separator 8 sold by Wuxi Lebiao Filtration Equipment Co., Ltd. under the trade name of oil-water coalescing separator, and is refined by a multi-stage vacuum distillation method to obtain a product containing unreacted allyl chloride and the solvent for recovery, and also to obtain an epichlorohydrin product; the oil phase is sent from the bottom of the liquid phase separator 8 through a pipeline to the heavy component refining process, and is refined by a vacuum distillation method after stripping to obtain the epichlorohydrin product.

[0138] The results of this embodiment are shown in Table 1 according to the method described in the specification of this application.

[0139] Table 1: Implementation results of Examples 1-4

[0140]

Claims

1. A method for preparing epichlorohydrin by hydrogen peroxide method, characterized in that The preparation steps of the preparation method are as follows: A. Pre-reaction Hydrogen peroxide, allyl chloride and a solvent are added from one side of the top of the pre-reaction kettle (1), and nitrogen is introduced from the same side of the top. A catalyst is added from the opposite side of the top of the pre-reaction kettle (1), and a pipe for discharging tail gas is installed on the top of the pre-reaction kettle (1); hydrogen peroxide and allyl chloride react for 30 to 90 minutes at a temperature of 20 to 40° C. and under stirring in the presence of the catalyst to obtain a pre-reaction liquid; B. Cyclic reaction The pre-reaction liquid obtained in step A is sent from the bottom of the pre-reaction kettle (1) to the top of the circulation reactor (3) through a pipeline by a pre-reaction liquid pump (2), and nitrogen is introduced from the top of the circulation reactor (3), and a pipeline for discharging tail gas is installed at the top of the circulation reactor (3); the pre-reaction liquid is reacted at a temperature of 20 to 40° C. and stirred for 60 to 120 minutes to obtain a mixture solution containing epichlorohydrin, allyl chloride, a catalyst, a solvent and water; C. Catalyst separation The mixed solution obtained in step B is discharged from the bottom of the circulating reactor (3), and is sent to the bottom of the ceramic membrane filter (5) by the circulating reaction pump (4), and filtered and separated by the ceramic membrane filter (5) to obtain a concentrated solution containing the catalyst and a clear solution without the catalyst; when the catalyst contained in the concentrated solution still has catalytic activity, the concentrated solution is returned to the top of the circulating reactor (3) through the pipeline through the A pipe port and the B pipe port of the membrane filter three-way switch (9) located at the top of the ceramic membrane filter (5); when the catalyst contained in the concentrated solution has no catalytic activity, the concentrated solution containing the deactivated catalyst is discharged from the pipeline through the A pipe port and the C pipe port of the membrane filter three-way switch (9); the clear solution is sent to the clear solution storage tank (7) through the pipeline located at the upper end of the side wall of the ceramic membrane filter (5) through the A pipe port and the B pipe port of the three-way switch (10) on the clear solution storage tank for storage, and the clear solution contains epichlorohydrin, allyl chloride, solvent and water; D. Backwash When the filtration efficiency of the ceramic membrane filter (5) decreases by less than 40%, under the condition of closing the three-way switch (10) on the clear liquid storage tank, the clear liquid in the clear liquid storage tank (7) is sent from the bottom of the clear liquid storage tank (7) through the A pipe opening and the B pipe opening of the three-way switch (11) below the clear liquid storage tank and the pipeline by the backwashing pump (6) to the lower part of the ceramic membrane filter (5), so that the clear liquid backwashes the ceramic membrane filter (5) until the filtration efficiency of the ceramic membrane filter (5) reaches more than 90%, and then the backwashing is stopped, and then the three-way switch (10) on the clear liquid storage tank is opened, and the backwashing liquid collected in the upper part of the ceramic membrane filter (5) is sent to the clear liquid storage tank (7) through the pipeline and the A pipe opening and the B pipe opening of the three-way switch (10) on the clear liquid storage tank; E. Oil-water separation The clear liquid obtained in step C is sent from the bottom of the clear liquid storage tank (7) through the A and C pipe ports of the three-way switch (11) below the clear liquid storage tank and a pipeline to the upper part of the liquid phase separator (8), and the water phase and the oil phase are separated under the condition of continuous feeding and discharging. The water phase is sent from the upper part of the liquid phase separator (8) through a pipeline to the light component refining process, and is refined by a multi-stage vacuum distillation method to obtain a product containing unreacted allyl chloride and solvent for recovery, and an epichlorohydrin product is also obtained. The oil phase is sent from the bottom of the liquid phase separator (8) through a pipeline to the heavy component refining process, and is refined by a vacuum distillation method after stripping to obtain the epichlorohydrin product.

2. The preparation method according to claim 1, characterized in that In step A, the molar ratio of hydrogen peroxide to allyl chloride is 1:1-5; the molar ratio of hydrogen peroxide to solvent is 1:1-4; and the amount of catalyst used is 0.5%-5.0% based on the total weight of hydrogen peroxide and allyl chloride.

3. The preparation method according to claim 1 or 2, characterized in that In step A, the solvent is one or more solvents selected from methanol, ethanol, n-propanol, isopropanol, acetone or acetonitrile.

4. The preparation method according to claim 1 or 2, characterized in that In step A, the concentration of the hydrogen peroxide is 20% to 50% by weight of hydrogen peroxide.

5. The preparation method according to claim 1, characterized in that In step A and step B, the flow rate of nitrogen is 10-1000 ml / min.

6. The preparation method according to claim 1, characterized in that In step A, the catalyst is TS-1, TS-2 type titanium silicon molecular sieve or Ti-MCM-41, Ti-SBA-15 type mesoporous molecular sieve.

7. The preparation method according to claim 1, characterized in that In step A and step B, the pre-reactor (1) and the circulation reactor (3) are reactors formed by connecting an upper semicircular structure, a middle cylindrical structure and a lower conical structure.

8. The preparation method according to claim 1, characterized in that In step C, the ceramic membrane filter (5) is a filter with a cylindrical barrel structure, in which a tubular ceramic membrane filter medium with a pore size of 1 to 10 nm is filled.

9. The preparation method according to claim 1, characterized in that In step D, the clear liquid storage tank (7) is a vertical storage tank formed by connecting an upper circular structure, a middle cylindrical structure and a lower circular structure.

10. The preparation method according to claim 1, characterized in that In step D, the liquid phase separator (8) is a vertical separation tank structure, which is composed of an elliptical head at the upper end, a cylindrical tank body structure in the middle and a U-shaped pipe outlet at the lower end.

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