Device and method for synthesizing epichlorohydrin by continuous oxidation method

Abstract

The invention belongs to the technical field of synthesis and devices of organic matters, and particularly relates to a continuous oxidation method epoxy chloropropane synthesis device and method. The continuous oxidation-process epoxy chloropropane synthesis method comprises the following steps: respectively dissolving a raw material chloropropene and a raw material hydrogen peroxide in a solvent, and respectively pumping obtained feed liquids into a micro-mixer to obtain a mixed material; conveying the mixed material into a micro-packed bed for reaction, adding water, and extracting to obtain a dichloromethane solution containing epoxy chloropropane; and washing the dichloromethane solution containing the epichlorohydrin by using a saturated sodium thiosulfate solution, drying and filtering an organic phase, and carrying out reduced pressure distillation on a crude product to obtain a pure product. The continuous oxidation-process epoxy chloropropane synthesis method provided by the invention is simple in process and high in reaction efficiency, and the synthesized epoxy chloropropane is high in purity and high in yield. According to the continuous synthesis device for epoxy chloropropane, the utilization rate of the catalyst is increased, the safety is high, and side reactions are reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of organic matter synthesis and devices, and specifically relates to a continuous oxidation process epichlorohydrin synthesis device and method. Background Art

[0002] Epichlorohydrin, also known as 3-chloro-1,2-epoxypropane, referred to as ECH, has a chemical formula of C3H5ClO. It is a colorless liquid with an organic compound with a chloroform-like odor. It is volatile, flammable and highly active. Epichlorohydrin is an important organic chemical raw material and petrochemical intermediate. It is mainly used in the production of epoxy resins, curing agent triglycidyl isocyanurate (TGIC) and cationic etherifying agents; it can also be used in the production of chlorohydrin rubber, ion exchange resins, surfactants and plasticizers, etc. It can also be used as a solvent for cellulose esters and resins, and is widely used in the fields of chemical industry, electronic appliances, etc. It can also be used as a pharmaceutical synthesis intermediate. For example, the synthesis of drugs such as β-adrenergic blocking drug Atilol, anesthetic baclofen, and diet drug L-carnitine requires the use of chiral epichlorohydrin as a raw material.

[0003] At present, the industrial production process of epichlorohydrin mainly includes three methods: propylene high temperature chlorination method, propylene acetate method and glycerol method. Among the above methods, propylene high temperature chlorination method is the most important production method at present, but it uses non-renewable resources as raw materials, which is not only costly but also not environmentally friendly. Therefore, in recent years, the glycerol method using biomass as raw materials has gradually developed and achieved industrial production on a certain scale. However, the last step of the production process of propylene high temperature chlorination method and glycerol method is the saponification reaction of dichloropropanol (DCH), which will produce a large amount of chlorine-containing wastewater and chloride salt waste residue. Therefore, considering the economic benefits and environmental problems of ECH production, it is necessary not only to improve the existing production process, but also to develop new synthesis methods and routes. In recent years, the direct epoxidation of allyl chloride has been increasingly valued by the industry and academia due to its mild reaction conditions, green reaction and low environmental pollution.

[0004] The direct epoxidation of allyl chloride to prepare epichlorohydrin is generally studied using hydrogen peroxide, peracid, alkoxy hydroperoxide, molecular oxygen, etc. as oxygen sources. Among them, hydrogen peroxide as an oxidant has been a hot topic in the research of catalytic epoxidation of olefins in recent years. At present, the main catalytic systems are titanium silicalite catalytic system and phosphotungstic acid heteropolyacid catalytic system. The titanium silicalite catalytic system has the advantages of mild reaction conditions and high selectivity for the target product, so it is the preferred catalytic system. Traditional autoclave reactors have large liquid holding capacity, potential safety hazards, and are difficult to achieve continuous production. Batch operations are cumbersome and it is difficult to increase production capacity. Therefore, it is urgent to develop a new process for the safe and efficient continuous synthesis of epichlorohydrin.

[0005] For example, the patent CN116514741A discloses a process for producing epichlorohydrin by microinterface reaction, wherein liquid chloropropylene is mixed with hydrogen peroxide and then enters a tube-type fixed bed reactor loaded with rare earth modified titanium silicon molecular sieve, and gaseous chloropropylene is broken into micron-sized bubbles by a microinterface generator and then enters a tube-type fixed bed reactor; in the fixed bed reactor, liquid chloropropylene and gaseous chloropropylene undergo epoxidation reaction with hydrogen peroxide to generate materials containing epichlorohydrin and water; the materials enter a three-phase separator to achieve three-phase separation of gas phase, oil phase and water phase; the oil phase enters a light removal distillation tower and a heavy removal distillation tower in turn, and epichlorohydrin is obtained at the top of the heavy removal distillation tower, and the yield and selectivity of epichlorohydrin are high, realizing industrial continuous production. However, the silicon titanium molecular sieve used needs to be modified, which increases the processing cost, and gasifies the chloropropylene to increase the micromixing effect, which not only increases energy loss but also increases waste gas generation, and increases the consumption of chloropropylene.

[0006] For example, CN110156725A, CN112062736A, and CN110078684A all disclose using a microchannel reactor as a reaction device to achieve continuous synthesis of epichlorohydrin. However, the gradient feeding method adopted in CN110156725A increases the production steps and the reaction steps are complicated; the post-treatment steps of CN112062736A are complicated and require filtering the catalyst through a membrane separator; the subsequent slurry-like catalytic recovery and regeneration of CN110078684A is difficult, and the water-soluble manganese complex catalyst used is not a mature product on the market, and the quality cannot be guaranteed. In addition, the cost of purchasing the corresponding synthesis reagents is high, and it is also necessary to produce them by oneself, which greatly increases the production cost. Summary of the invention

[0007] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a continuous oxidation process for synthesizing epichlorohydrin, which has a simple process, high reaction efficiency, and the synthesized epichlorohydrin has high purity and high yield.

[0008] The present invention also provides a synthesis device for continuous synthesis of epichlorohydrin, which improves the utilization rate of the catalyst, has high safety, and reduces side reactions.

[0009] The continuous oxidation process for synthesizing epichlorohydrin of the present invention comprises the following steps:

[0010] (1) dissolving the raw material allyl chloride in a solvent to prepare a feed liquid 1; dissolving the raw material hydrogen peroxide in a solvent to prepare a feed liquid 2;

[0011] (2) pumping liquid 1 and liquid 2 into a micro mixer respectively to obtain a mixed material;

[0012] (3) transporting the mixed material to a micro-packed bed filled with TS-1 catalyst for reaction, and maintaining the reaction temperature in a constant temperature water bath to obtain a liquid containing epichlorohydrin;

[0013] (4) adding deionized water to the liquid containing epichlorohydrin, mixing, extracting with dichloromethane, separating the liquids and retaining the organic phase to obtain a dichloromethane solution containing epichlorohydrin;

[0014] (5) washing the dichloromethane solution containing epichlorohydrin with a saturated sodium thiosulfate solution, retaining the organic phase, drying and filtering the organic phase, and removing the organic solvent from the filtrate by rotary evaporation to obtain a crude product of epichlorohydrin;

[0015] (6) The crude epichlorohydrin is subjected to reduced pressure distillation to obtain pure epichlorohydrin.

[0016] In step (1), the molar ratio of allyl chloride to hydrogen peroxide is 1:(1-1.5); and the solvent is acetone or methanol.

[0017] In step (1), the molar concentration of allyl chloride in the feed solution 1 is 1.72-2.82 mol / L, and the mass fraction of hydrogen peroxide in the feed solution 2 is 35-50%.

[0018] In step (2), the flow rate of the feed liquid 1 and the feed liquid 2 pumped into the micro mixer is 0.15-2 mL / min.

[0019] The reaction temperature in step (3) is 27-39° C., and the reaction time is 3.5-6 min.

[0020] The TS-1 catalyst described in step (3) is a titanium silicon molecular sieve catalyst, which is in the form of spherical particles with a diameter of 1-2 mm. The length of the micro-packed bed is 30 cm, the inner diameter of the tubular is 1 cm, and the material is 316L stainless steel.

[0021] In step (4), the volume ratio of the liquid containing epichlorohydrin to deionized water is 1:(0.5-1).

[0022] In step (5), the volume ratio of the dichloromethane solution containing epichlorohydrin to the saturated sodium thiosulfate solution is 1:(0.25-0.5); and the rotary evaporation temperature is 30-35°C.

[0023] The temperature of the reduced pressure distillation in step (6) is 70-80°C.

[0024] The synthesis device used in the continuous oxidation process for synthesizing epichlorohydrin includes a horizontal flow pump, a preheater, a micro mixer, and a micro packed bed. The feed liquid pipeline and the feed liquid pipeline are respectively connected to the two horizontal flow pumps, the outlets of the two horizontal flow pumps are connected to the micro mixer through two channels, and preheaters are respectively provided on the two pipelines entering the inlet of the micro mixer, and the outlet of the micro mixer is connected to the micro packed bed.

[0025] Specifically, the continuous oxidation process for synthesizing epichlorohydrin comprises the following steps:

[0026] (1) dissolving the raw material allyl chloride in solvent acetone or methanol to prepare a feed liquid 1 having a molar concentration of allyl chloride of 1.72-2.82 mol / L; dissolving the raw material hydrogen peroxide in solvent acetone or methanol to prepare a feed liquid 2 having a mass fraction of hydrogen peroxide of 35-50%. The molar ratio of allyl chloride to hydrogen peroxide is 1:(1-1.5).

[0027] (2) Feed liquid 1 and feed liquid 2 are respectively pumped into a micro mixer at a flow rate of 0.15-2 mL / min through a horizontal flow pump and mixed evenly to obtain a mixed material.

[0028] (3) The mixed material is transported to a micro-packed bed filled with TS-1 catalyst for reaction. TS-1 catalyst is a titanium silicon molecular sieve catalyst in the form of spherical particles with a diameter of 1-2 mm. The filling amount is preferably 30%-50% of the volume of the micro-packed bed to ensure catalytic efficiency and reduce mechanical loss. The length of the micro-packed bed is 30 cm, the inner diameter of the tubular is 1 cm, and the material is 316L stainless steel. During the reaction, a constant temperature water bath is used to maintain the reaction temperature at 27-39°C, and the reaction time is 3.5-6 minutes to obtain a liquid containing epichlorohydrin.

[0029] (4) adding deionized water to the liquid containing epichlorohydrin and mixing the mixture, wherein the volume ratio of the deionized water to the liquid containing epichlorohydrin is 1:(0.5-1), then extracting the mixture with dichloromethane, retaining the organic phase after separation, and obtaining a dichloromethane solution containing epichlorohydrin.

[0030] (5) washing the dichloromethane solution containing epichlorohydrin with a saturated sodium thiosulfate solution. During the washing process, the volume ratio of the dichloromethane solution containing epichlorohydrin to the saturated sodium thiosulfate solution is 1:(0.25-0.5). After washing, the organic phase is retained to achieve the purpose of removing hydrogen peroxide in the organic phase, and the organic phase is dried and filtered. The filtrate is subjected to rotary evaporation at 30-35° C. to remove the organic solvent to obtain a crude product of epichlorohydrin.

[0031] (6) The crude epichlorohydrin is subjected to reduced pressure distillation at 70-80°C to obtain pure epichlorohydrin.

[0032] The reaction formula of epichlorohydrin synthesis stage in the present invention is:

[0033]

[0034] Micro-reaction continuousization refers to the process of continuously producing chemicals and drugs in microreactor pipes with sizes in the micrometer and millimeter levels. The continuous flow microreactor has good heat and mass transfer performance and low liquid holdup, and is safe, environmentally friendly, efficient and low in energy consumption. The continuous oxidation method for synthesizing epichlorohydrin of the present invention uses micro-reaction technology to achieve the continuous synthesis of olefin epoxidation reaction, and transforms the kettle synthesis process that originally required a long time and complicated steps into a continuous synthesis process. The process is simple, the reaction time is short, the temperature control of the equipment is more accurate, the explosion risk of peroxides is avoided, and the subsequent purification steps can be reduced to reduce product loss.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) The continuous oxidation method for synthesizing epichlorohydrin of the present invention realizes the continuous synthesis of epichlorohydrin. Compared with the traditional kettle synthesis process, the process is simple and the reaction time is short.

[0037] (2) The continuous oxidation method for synthesizing epichlorohydrin of the present invention has a continuous reaction, is easy to monitor and control the reaction process, and uses a micro-mixer for reaction. Its smaller characteristic size enhances the heat and mass transfer effect of the reaction materials, makes the temperature control of the equipment more precise, reduces side reactions, improves product selectivity, and avoids the safety risk of explosion of peroxides.

[0038] (3) The continuous synthesis device of epichlorohydrin of the present invention can achieve rapid and efficient mixing of two fluids in a micromixer, instantly achieving a uniform reaction environment, high reaction efficiency, and easy scale-up; the use of a micropacked bed can effectively reduce the mechanical loss of the catalyst, improve the catalyst utilization rate, and eliminate the step of filtering the catalyst from the reaction liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic diagram of the continuous synthesis of epichlorohydrin according to the present invention.

[0040] In the figure: 1. Horizontal flow pump; 2. Preheater; 3. Micro mixer; 4. Micro packed bed. DETAILED DESCRIPTION

[0041] The present invention will be further described below in conjunction with specific embodiments.

[0042] like Figure 1As shown, the synthesis device used in the continuous oxidation process for epichlorohydrin synthesis comprises a horizontal flow pump 1, a preheater 2, a micro mixer 3, and a micro packed bed 4. The pipeline of the feed liquid 1 and the pipeline of the feed liquid 2 are respectively connected to the horizontal flow pump 1 of the two routes, and the outlets of the horizontal flow pumps 1 of the two routes are connected to the micro mixer 3 through two routes, and the preheater 2 is respectively provided on the two routes of the pipeline entering the inlet of the micro mixer 3, and the outlet of the micro mixer 3 is connected to the micro packed bed 4. The filling amount of the TS-1 catalyst in the micro packed bed 4 is preferably 95% of the volume of the micro packed bed.

[0043] The micro mixer 3 is a T-type micro mixer with a specification of 0.25 mm.

[0044] The micro-packed bed 4 is an empty column tube of a liquid chromatography column with an inner diameter of 10 mm.

[0045] The following examples and comparative examples are all based on the above Figure 1 carried out.

[0046] The TS-1 catalyst used below is a titanium silicon molecular sieve catalyst in the form of spherical particles with a diameter of 1-2 mm to ensure catalytic efficiency and reduce mechanical loss. The length of the micro-packed bed is 30 cm, the inner diameter of the tubular is 1 cm, and the material is 316L stainless steel.

[0047] Example 1

[0048] The continuous oxidation process for synthesizing epichlorohydrin comprises the following steps:

[0049] (1) The raw material allyl chloride is dissolved in the solvent methanol to prepare a feed liquid 1 with a molar concentration of allyl chloride of 2.16 mol / L; the raw material hydrogen peroxide is dissolved in the solvent methanol to prepare a feed liquid 2 with a mass fraction of hydrogen peroxide of 35%. The molar ratio of allyl chloride to hydrogen peroxide is 1:1.2.

[0050] (2) Feed liquid 1 and feed liquid 2 were respectively pumped into a micro mixer at a flow rate of 0.42 mL / min through a horizontal flow pump and mixed evenly to obtain a mixed material.

[0051] (3) The mixed material was transported to a micro-packed bed filled with TS-1 catalyst for reaction. During the reaction, the temperature of the water bath was set to 33° C. and the reaction time was 3.5 min. A liquid containing epichlorohydrin was obtained. The conversion rate was 97.8% and the yield was 96.17% as measured by high performance gas chromatography.

[0052] (4) adding deionized water to the liquid containing epichlorohydrin and mixing, wherein the volume ratio of deionized water to the liquid containing epichlorohydrin is 1:0.5, extracting with 0.5 times the volume of dichloromethane of the reaction liquid, retaining the organic phase after separation, and obtaining a dichloromethane solution containing epichlorohydrin.

[0053] (5) washing the dichloromethane solution containing epichlorohydrin with a saturated sodium thiosulfate solution. During the washing process, the volume ratio of the dichloromethane solution containing epichlorohydrin to the saturated sodium thiosulfate solution is 1:0.25. After washing, the organic phase is retained to achieve the purpose of removing hydrogen peroxide in the organic phase, and the organic phase is dried and filtered. The filtrate is subjected to rotary evaporation at 35° C. to remove the organic solvent to obtain a crude product of epichlorohydrin.

[0054] (6) The crude epichlorohydrin was subjected to reduced pressure distillation at 80°C to obtain pure epichlorohydrin with a purity of 99.80% and an actual yield of 92.35%.

[0055] (7) After running continuously for 72 hours, the catalyst was taken out, dried and weighed. The weight change was less than 1%. After being calcined in a muffle furnace for regeneration, the catalyst was continuously loaded into the packed bed and the reaction was continued for 8 hours. The average yield was detected every hour and was 95.50%.

[0056] Example 2

[0057] The continuous oxidation process for synthesizing epichlorohydrin comprises the following steps:

[0058] (1) dissolving the raw material allyl chloride in the solvent methanol to prepare a feed solution 1 with a molar concentration of allyl chloride of 2.6 mol / L; dissolving the raw material hydrogen peroxide in the solvent methanol to prepare a feed solution 2 with a mass fraction of hydrogen peroxide of 35%. The molar ratio of allyl chloride to hydrogen peroxide is 1:1.2.

[0059] (2) Feed liquid 1 and feed liquid 2 were respectively pumped into a micro mixer at a flow rate of 0.42 mL / min through a horizontal flow pump and mixed evenly to obtain a mixed material.

[0060] (3) The mixed material was transported to a micro-packed bed filled with TS-1 catalyst for reaction. During the reaction, the temperature of the water bath was set to 27° C. and the reaction time was 6 min. A liquid containing epichlorohydrin was obtained. The conversion rate was 95.4% and the yield was 92.9% as measured by high performance gas chromatography.

[0061] (4) adding deionized water to the liquid containing epichlorohydrin and mixing, wherein the volume ratio of deionized water to the liquid containing epichlorohydrin is 1:0.5, extracting with 0.5 times the volume of dichloromethane of the reaction liquid, retaining the organic phase after separation, and obtaining a dichloromethane solution containing epichlorohydrin.

[0062] (5) washing the dichloromethane solution containing epichlorohydrin with a saturated sodium thiosulfate solution. During the washing process, the volume ratio of the dichloromethane solution containing epichlorohydrin to the saturated sodium thiosulfate solution is 1:0.25. After washing, the organic phase is retained to achieve the purpose of removing hydrogen peroxide in the organic phase, and the organic phase is dried and filtered. The filtrate is subjected to rotary evaporation at 30° C. to remove the organic solvent to obtain a crude product of epichlorohydrin.

[0063] (6) The crude epichlorohydrin was subjected to reduced pressure distillation at 70°C to obtain pure epichlorohydrin with a purity of 99.89% and an actual yield of 90.12%.

[0064] (7) After running continuously for 72 hours, the catalyst was taken out, dried and weighed. The weight change was less than 0.8%. After being calcined in a muffle furnace for regeneration, the catalyst was continuously loaded into the packed bed and the reaction was continued for 8 hours. The average yield was detected every hour and was 93.4%.

[0065] Example 3

[0066] The continuous oxidation process for synthesizing epichlorohydrin comprises the following steps:

[0067] (1) dissolving the raw material allyl chloride in the solvent methanol to prepare a feed solution 1 with a molar concentration of allyl chloride of 2.6 mol / L; dissolving the raw material hydrogen peroxide in the solvent methanol to prepare a feed solution 2 with a mass fraction of hydrogen peroxide of 50%. The molar ratio of allyl chloride to hydrogen peroxide is 1:1.2.

[0068] (2) Feed liquid 1 and feed liquid 2 were respectively pumped into a micro mixer at a flow rate of 0.42 mL / min through a horizontal flow pump and mixed evenly to obtain a mixed material.

[0069] (3) The mixed material was transported to a micro-packed bed filled with TS-1 catalyst for reaction. During the reaction, the temperature of the water bath was set to 33° C. and the reaction time was 6 min. A liquid containing epichlorohydrin was obtained. The conversion rate was 98.8% and the yield was 96.08% as measured by high performance gas chromatography.

[0070] (4) adding deionized water to the liquid containing epichlorohydrin and mixing, wherein the volume ratio of deionized water to the liquid containing epichlorohydrin is 1:0.75, extracting with 0.75 times the volume of dichloromethane of the reaction liquid, retaining the organic phase after separation, and obtaining a dichloromethane solution containing epichlorohydrin.

[0071] (5) washing the dichloromethane solution containing epichlorohydrin with a saturated sodium thiosulfate solution. During the washing process, the volume ratio of the dichloromethane solution containing epichlorohydrin to the saturated sodium thiosulfate solution is 1:0.25. After washing, the organic phase is retained to achieve the purpose of removing hydrogen peroxide in the organic phase, and the organic phase is dried and filtered. The filtrate is subjected to rotary evaporation at 33° C. to remove the organic solvent to obtain a crude product of epichlorohydrin.

[0072] (6) The crude epichlorohydrin is subjected to reduced pressure distillation at 75°C to obtain pure epichlorohydrin. The purity of the product can reach 99.67% and the actual yield is 92.6%.

[0073] (7) After running continuously for 72 hours, the catalyst was taken out, dried and weighed. The weight change was less than 0.95%. After being calcined in a muffle furnace for regeneration, the catalyst was continuously loaded into the packed bed and the reaction was continued for 8 hours. The average yield was detected every hour and was 96.4%.

[0074] Example 4

[0075] The continuous oxidation process for synthesizing epichlorohydrin comprises the following steps:

[0076] (1) dissolving the raw material allyl chloride in solvent acetone or methanol to prepare a feed solution 1 with a molar concentration of allyl chloride of 1.72 mol / L; dissolving the raw material hydrogen peroxide in solvent acetone or methanol to prepare a feed solution 2 with a mass fraction of hydrogen peroxide of 50%. The molar ratio of allyl chloride to hydrogen peroxide is 1:1.5.

[0077] (2) Feed liquid 1 and feed liquid 2 were respectively pumped into a micro mixer at a flow rate of 1.0 mL / min through a horizontal flow pump and mixed evenly to obtain a mixed material.

[0078] (3) The mixed material was transported to a micro-packed bed filled with TS-1 catalyst for reaction. During the reaction, the temperature of the water bath was set to 33° C. and the reaction time was 6 min. A liquid containing epichlorohydrin was obtained. The conversion rate was 100% and the yield was 97.20% as measured by high performance gas chromatography.

[0079] (4) adding deionized water to the liquid containing epichlorohydrin and mixing, wherein the volume ratio of deionized water to the liquid containing epichlorohydrin is 1:1, extracting with dichloromethane of 1 times the volume of the reaction liquid, retaining the organic phase after separation, and obtaining a dichloromethane solution containing epichlorohydrin.

[0080] (5) washing the dichloromethane solution containing epichlorohydrin with a saturated sodium thiosulfate solution. During the washing process, the volume ratio of the dichloromethane solution containing epichlorohydrin to the saturated sodium thiosulfate solution is 1:0.25. After washing, the organic phase is retained to achieve the purpose of removing hydrogen peroxide in the organic phase, and the organic phase is dried and filtered. The filtrate is subjected to rotary evaporation at 35° C. to remove the organic solvent to obtain a crude product of epichlorohydrin.

[0081] (6) The crude epichlorohydrin was subjected to reduced pressure distillation at 80°C to obtain pure epichlorohydrin with a purity of 99.79% and an actual yield of 94.06%.

[0082] (7) After running continuously for 72 hours, the catalyst was taken out, dried and weighed. The weight change was less than 1.1%. After being calcined in a muffle furnace for regeneration, the catalyst was continuously loaded into the packed bed and the reaction was continued for 8 hours. The average yield was detected every hour and was 96.6%.

[0083] Example 5

[0084] The continuous oxidation process for synthesizing epichlorohydrin comprises the following steps:

[0085] (1) dissolving the raw material allyl chloride in solvent acetone or methanol to prepare a feed solution 1 with a molar concentration of allyl chloride of 2.82 mol / L; dissolving the raw material hydrogen peroxide in solvent acetone or methanol to prepare a feed solution 2 with a mass fraction of hydrogen peroxide of 50%. The molar ratio of allyl chloride to hydrogen peroxide is 1:1.5.

[0086] (2) Feed liquid 1 and feed liquid 2 were respectively pumped into a micro mixer at a flow rate of 2.0 mL / min through a horizontal flow pump and mixed evenly to obtain a mixed material.

[0087] (3) The mixed material was transported to a micro-packed bed filled with TS-1 catalyst for reaction. During the reaction, the temperature of the water bath was set to 33° C. and the reaction time was 3.5 min. A liquid containing epichlorohydrin was obtained. The conversion rate was 98.2% and the yield was 97.87% as measured by high performance gas chromatography.

[0088] (4) adding deionized water to the liquid containing epichlorohydrin and mixing, wherein the volume ratio of deionized water to the liquid containing epichlorohydrin is 1:0.5, extracting with 0.5 times the volume of dichloromethane of the reaction liquid, retaining the organic phase after separation, and obtaining a dichloromethane solution containing epichlorohydrin.

[0089] (5) washing the dichloromethane solution containing epichlorohydrin with a saturated sodium thiosulfate solution. During the washing process, the volume ratio of the dichloromethane solution containing epichlorohydrin to the saturated sodium thiosulfate solution is 1:0.25. After washing, the organic phase is retained to achieve the purpose of removing hydrogen peroxide in the organic phase, and the organic phase is dried and filtered. The filtrate is subjected to rotary evaporation at 30° C. to remove the organic solvent to obtain a crude product of epichlorohydrin.

[0090] (6) The crude epichlorohydrin was subjected to reduced pressure distillation at 70°C to obtain pure epichlorohydrin with an actual yield of 93.7%.

[0091] (7) After running continuously for 72 hours, the catalyst was taken out, dried and weighed. The weight change was less than 0.9%. After being calcined in a muffle furnace for regeneration, the catalyst was continuously loaded into the packed bed and the reaction was continued for 8 hours. The average yield was detected every hour and was 96.9%.

[0092] Comparative Example 1

[0093] This comparative example is the same as Example 1, except that the spherical TS-1 with a diameter of 1-2.0 mm in step (1) is replaced with a spherical TS-1 with a diameter of 2.1-3 mm, and other preparation conditions are the same. Then, a liquid containing epichlorohydrin is obtained, and its conversion rate is 87.3% and its yield is 71.6% as measured by high performance gas chromatography.

[0094] Comparative Example 2

[0095] This comparative example is the same as Example 3, except that the water bath temperature in step (3) is set at 43°C instead of 33°C, and other preparation conditions are the same. Then, a liquid containing epichlorohydrin is obtained, and its conversion rate is 99.8% and its yield is 76.2% as measured by high performance gas chromatography.

[0096] Comparative Example 3

[0097] This comparative example is the same as Example 3, except that the molar ratio of allyl chloride to hydrogen peroxide in step (1) is 1:1.5, while the molar ratio of allyl chloride to hydrogen peroxide is 1:2, and other preparation conditions are the same. Then, a liquid containing epichlorohydrin is obtained, and its conversion rate is 100% and the yield is 80.7% as measured by high performance gas chromatography.

Claims

1. A continuous oxidation process for synthesizing epichlorohydrin, characterized in that: The following steps are involved: (1) dissolving the raw material allyl chloride in a solvent to prepare a feed liquid 1; dissolving the raw material hydrogen peroxide in a solvent to prepare a feed liquid 2; (2) pumping feed liquid 1 and feed liquid 2 into a micro mixer respectively to obtain a mixed material; (3) transporting the mixed material to a micro-packed bed filled with TS-1 catalyst for reaction, and maintaining the reaction temperature in a constant temperature water bath to obtain a liquid containing epichlorohydrin; (4) adding deionized water to the liquid containing epichlorohydrin, mixing, extracting with dichloromethane, separating the liquids and retaining the organic phase to obtain a dichloromethane solution containing epichlorohydrin; (5) washing the dichloromethane solution containing epichlorohydrin with a saturated sodium thiosulfate solution, retaining the organic phase, and drying, filtering, and rotary evaporating the organic phase to obtain a crude product of epichlorohydrin; (6) The crude epichlorohydrin is subjected to reduced pressure distillation to obtain pure epichlorohydrin.

2. The continuous oxidation process for synthesizing epichlorohydrin according to claim 1, characterized in that: In step (1), the molar ratio of allyl chloride to hydrogen peroxide is 1:(1-1.5); and the solvent is acetone or methanol.

3. The continuous oxidation process for synthesizing epichlorohydrin according to claim 1, characterized in that: In step (1), the molar concentration of allyl chloride in the feed solution 1 is 1.72-2.82 mol / L, and the mass fraction of hydrogen peroxide in the feed solution 2 is 35-50%.

4. The continuous oxidation process for synthesizing epichlorohydrin according to claim 1, characterized in that: In step (2), the flow rate of the feed liquid 1 and the feed liquid 2 pumped into the micro mixer is 0.15-2 mL / min.

5. The continuous oxidation process for synthesizing epichlorohydrin according to claim 1, characterized in that: The reaction temperature in step (3) is 27-39° C., and the reaction time is 3.5-6 min.

6. The continuous oxidation process for synthesizing epichlorohydrin according to claim 1, characterized in that: The TS-1 catalyst described in step (3) is a titanium silicon molecular sieve catalyst, which is in the form of spherical particles with a diameter of 1-2 mm. The length of the micro-packed bed is 30 cm, the inner diameter of the tubular is 1 cm, and the material is 316L stainless steel.

7. The continuous oxidation process for epichlorohydrin synthesis according to claim 1, characterized in that: In step (4), the volume ratio of the liquid containing epichlorohydrin to deionized water is 1:(0.5-1).

8. The continuous oxidation process for synthesizing epichlorohydrin according to claim 1, characterized in that: In step (5), the volume ratio of the dichloromethane solution containing epichlorohydrin to the saturated sodium thiosulfate solution is 1:(0.25-0.5); and the rotary evaporation temperature is 30-35°C.

9. The continuous oxidation process for synthesizing epichlorohydrin according to claim 1, characterized in that: The temperature of the reduced pressure distillation in step (6) is 70-80°C.

10. A synthesis device used in the continuous oxidation process for epichlorohydrin synthesis according to any one of claims 1 to 9, characterized in that: The invention comprises a horizontal flow pump (1), a preheater (2), a micro mixer (3), and a micro packed bed (4). The pipeline of the feed liquid 1 and the pipeline of the feed liquid 2 are respectively connected to the horizontal flow pumps (1) of the two routes. The outlets of the horizontal flow pumps (1) of the two routes are connected to the micro mixer (3) through two routes. The preheater (2) is respectively arranged on the two pipelines entering the inlet of the micro mixer (3). The outlet of the micro mixer (3) is connected to the micro packed bed (4).

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