A kind of preparation method of epichlorohydrin

Abstract

The present invention relates to the technical field of fine chemical products, and in particular to a method for preparing epichlorohydrin. Comprise the following steps: (1) at room temperature, extract dichlorohydrin hydrochloric acid water using an organic solvent, stratify to obtain an organic phase one and an aqueous phase one, and collect the organic phase one; (2) transfer the organic phase one into a cyclization reactor, heat to a set temperature, and under stirring, add the prepared alkali solution into the cyclization reactor to obtain a cyclization reaction liquid; (3) transfer the cyclization reaction liquid into a liquid separator and stratify to obtain an organic phase two and an aqueous phase two, and the aqueous phase two is extracted 2-3 times using an organic solvent, and the organic phase obtained by extraction is incorporated into the organic phase two; (4) the organic phase two is transferred to a distillation tower for rectification to obtain epichlorohydrin, an organic solvent and a rectifying kettle residue. The present invention realizes the integration and continuity of dichlorohydrin separation, cyclization and epichlorohydrin separation.

Description

Technical Field

[0001] The invention relates to the technical field of fine chemical products, and in particular to a method for preparing epichlorohydrin. Background Art

[0002] Epichlorohydrin is an important organic chemical raw material and fine chemical product. It is the main raw material for the production of epoxy resin, epichlorohydrin rubber, nitroglycerin explosives, fiberglass, and electrical insulation products. It can also be used to produce adhesives, cation exchange resins, etc.

[0003] The production method of epichlorohydrin includes propylene high temperature chlorination method, propylene acetate method and glycerol method, all of which are to prepare dichloropropanol first, and then dichloropropanol undergoes cyclization reaction under alkaline conditions to generate epichlorohydrin. At present, the cyclization reaction of dichloropropanol is mostly based on refined dichloropropanol as raw material and aqueous phase as reaction solvent. As the concentration of epichlorohydrin in the reaction solution continues to increase, epichlorohydrin will react with water to generate by-products such as dichloropropanol. This not only causes the yield of epichlorohydrin to decrease, but also increases the difficulty of subsequent separation. At present, the method for solving this problem mainly includes reducing the reaction temperature, controlling the cyclization reaction time, using organic solvents as reaction solvents, and adopting reaction-distillation coupling technology.

[0004] Patent CN102603680B uses a microchannel reactor, and an aqueous solution of dichloropropanol and hydrogen chloride reacts with sodium hydroxide at 90°C for 10s. The conversion rate of dichloropropanol and the selectivity of epichlorohydrin are 98% and 99.4%, respectively. As the reaction temperature increases and the time is prolonged, the conversion rate of dichloropropanol increases, but the selectivity of epichlorohydrin decreases. Patents CN103709124B and CN103539763B respectively use reaction-distillation coupling technology and thin film evaporator coupling technology to distill out the epichlorohydrin generated by the reaction in time. Patent CN106632149B uses a two-step saponification method. First, dichloropropanol is cyclized at normal pressure, and then the generated oil layer is distilled to obtain epichlorohydrin. Finally, the residual water in the distillation kettle is washed and then secondary cyclization is carried out under negative pressure.

[0005] Patent CN101230052B discloses a method for preparing epichlorohydrin from a non-aqueous system. The method adds an organic solvent, dichloropropanol, an inorganic base, and a phase transfer catalyst into a reactor and reacts at 80-140°C for 2-8 hours. When the water is equimolar with the dichloropropanol, the reaction reaches the end point, the generated salt is filtered out, and the epichlorohydrin is separated by rectification. Patent CN101481365B discloses a method for preparing epichlorohydrin from a dichloropropanol hydrochloric acid aqueous solution. The method first uses an organic solvent to extract the dichloropropanol hydrochloric acid aqueous solution, and then the organic phase is subjected to a cyclization reaction with a solid base, and water is distilled off during the reaction until the reaction ends when no water is produced. Patent CN103351363A discloses a method for preparing epichlorohydrin. The patent uses ethyl acetate as a solvent. The epichlorohydrin generated by the cyclization of dichloropropanol and alkaline water can be transferred to ethyl acetate in a timely manner to avoid the continued ring-opening reaction of epichlorohydrin.

[0006] In summary, the current method of cyclizing dichloropropanol to generate epichlorohydrin under alkaline conditions still has the following problems: (1) using refined dichloropropanol as a raw material, it is necessary to go through extraction and distillation steps to obtain refined dichloropropanol, which has high energy consumption and complicated steps; (2) the reaction-distillation method has high reaction temperature, large energy consumption and low efficiency; (3) the solubility of solid base in organic solvent is poor, the cyclization temperature is high and the time is long; (4) the inorganic salt generated by cyclization is insoluble in organic solvent, which reduces the solubility of the base in the organic solvent, thereby affecting the rate of the cyclization reaction. Summary of the invention

[0007] In view of the technical problems of high energy consumption, high cyclization temperature and long time in the existing production method of epichlorohydrin, the present invention provides a simple and efficient method for preparing epichlorohydrin from dichloropropanol hydrochloric acid water (dichloropropanol-hydrogen chloride-water mixed solution), which realizes the integration and continuous separation of dichloropropanol separation, cyclization and epichlorohydrin. The present invention first uses an organic solvent to extract dichloropropanol hydrochloric acid water, and the obtained organic phase directly reacts with alkali liquid to obtain epichlorohydrin, and the cyclized liquid is allowed to stand for stratification to achieve the separation of epichlorohydrin and the aqueous phase. The organic solvent is not only an extractant for separating dichloropropanol, but also a solvent and phase transfer reagent for the cyclization reaction, and also an extractant for separating epichlorohydrin.

[0008] The technical solution of the present invention is as follows:

[0009] A method for preparing epichlorohydrin comprises the following steps:

[0010] (1) extracting dichloropropanol hydrochloric acid water with an organic solvent at room temperature, allowing the mixture to stand for stratification to obtain an organic phase 1 and an aqueous phase 1, and collecting the organic phase 1;

[0011] (2) transferring the organic phase 1 into a cyclization reaction kettle, heating it to a set temperature, adding the prepared alkali solution into the cyclization reaction kettle under stirring, and stopping the reaction after a certain reaction time to obtain a cyclization reaction liquid;

[0012] The cyclization reaction equation is as follows:

[0013]

[0014] (3) transferring the cyclization reaction solution to a liquid separator and allowing it to stand for stratification to obtain an organic phase II and an aqueous phase II, extracting the aqueous phase II 2-3 times with an organic solvent, and incorporating the extracted organic phase into the organic phase II;

[0015] (4) The organic phase 2 is transferred to a distillation tower for distillation to obtain epichlorohydrin, an organic solvent and distillation still residue.

[0016] Furthermore, the dichloropropane hydrochloride water in step (1) is an azeotropic condensate formed by dichloropropane, HCl and water, wherein the mass concentration of dichloropropane is 32%-36%.

[0017] Furthermore, in step (1), the mass ratio of dichloropropane hydrochloride water to the organic solvent is 1:0.6-1.

[0018] Furthermore, the organic solvent in step (1) is one or more of dichloromethane, dichloroethane, chloroform and carbon tetrachloride, preferably dichloromethane and dichloroethane.

[0019] Furthermore, in step (2), the set temperature of the cyclization reactor is 30 to 70°C.

[0020] Furthermore, the alkali solution in step (2) is one or more of sodium hydroxide solution, potassium hydroxide solution, and calcium hydroxide solution.

[0021] Furthermore, the mass concentration of the alkali solution in step (2) is 14% to 20%.

[0022] Furthermore, in step (2), the molar ratio of the organic phase 1 to the hydroxide in the base is 1:1.05-1.3.

[0023] Furthermore, the reaction time of step (2) is 10 to 60 min, and the stirring speed is 110 to 130 r / min.

[0024] Furthermore, the organic solvent in step (3) is one or more of dichloromethane, dichloroethane, chloroform, and carbon tetrachloride, preferably dichloromethane and dichloroethane, and the standing time for stratification is 20 to 30 minutes.

[0025] Furthermore, in step (4), the distillation pressure is atmospheric pressure, and the organic solvent obtained by distillation is recycled as a solvent or an extractant for the cyclization reaction and an extractant for the chlorination reaction.

[0026] Furthermore, the distillation residue in step (4) is recovered and used as a raw material for the cyclization reaction in step (2).

[0027] The beneficial effects of the present invention are:

[0028] 1. The present invention uses dichloropropanol hydrochloric acid water as a raw material, which overcomes the problem that dichloropropanol in the prior art needs to be distilled before undergoing cyclization reaction. The present invention realizes the integration and continuous separation of dichloropropanol, cyclization and epichlorohydrin separation, while saving energy and reducing consumption.

[0029] 2. The selectivity of the cyclization reaction of dichloropropanol in the present invention is high, and only epichlorohydrin and unreacted raw materials are contained in the reaction solution, without by-products such as monochloropropanol and glycerol.

[0030] 3. The organic solvent in the present invention can be used as an extractant for dichloropropanol, and can efficiently extract dichloropropanol from dichloropropanol hydrochloric acid water, thereby realizing the separation of dichloropropanol and hydrogen chloride, and reducing the amount of alkali used in the cyclization reaction; as a phase transfer agent, the epichlorohydrin generated by the cyclization of dichloropropanol can be quickly transferred to the organic phase, thereby avoiding the ring-opening reaction of epichlorohydrin in long-term contact with water, and improving the efficiency of the cyclization reaction and the yield of epichlorohydrin; as an extractant for epichlorohydrin, epichlorohydrin can be efficiently extracted from the cyclization reaction liquid. The utilization rate is high and it is easy to recycle.

[0031] 4. In the present invention, the mixed solution of epichlorohydrin and organic solvent can be distilled to obtain high-purity epichlorohydrin product, and the organic solvent can be recycled as an extractant and a cyclization solvent.

[0032] 5. The reaction conditions of the present invention are mild, the process is simple, the energy consumption is low, the efficiency is high, and continuous production can be easily realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 It is the gas phase spectrum of the dichloropropanol cyclization reaction liquid obtained by the method of the present invention. DETAILED DESCRIPTION

[0035] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0036] Example 1

[0037] Weigh 37.60 kg of dichloropropanol hydrochloric acid water (mass concentration of dichloropropanol is 35.00%), use 7.52 kg of dichloromethane × 3 to extract three times at room temperature, collect 34.50 kg of organic phase and 25.40 kg of aqueous phase, and quantitatively analyze by gas chromatography, the mass fraction of dichloropropanol in the organic phase is 35.21%, and the extraction rate of dichloropropanol is 92.30%.

[0038] Add the organic phase 1 to the cyclization reactor, start stirring and heat to 30° C. Weigh 4.05 kg of sodium hydroxide and 17.00 kg of water to prepare a sodium hydroxide aqueous solution, pump the alkali solution into the cyclization reactor, continue stirring and reacting for 15 minutes after adding, and the stirring speed is 120 r / min.

[0039] The reaction solution was transferred to a static kettle and allowed to stand for 20 minutes, and the organic phase 2 and the aqueous phase 2 were obtained by stratification. The aqueous phase 2 was extracted three times with 3.00 kg of dichloromethane × 3, and the organic phase obtained by extraction was incorporated into the organic phase 2. The organic phase 2 was distilled under normal pressure to obtain 30.08 kg of dichloromethane (recovery rate 95.30%), which was recycled as a solvent or extractant for the cyclization reaction and an extractant for the chlorination reaction, and 8.43 kg of epichlorohydrin (yield 96.80%). The residue in the distillation kettle was recovered and used as a raw material for the cyclization reaction.

[0040] Example 2

[0041] Weigh 37.60 kg of dichloropropanol hydrochloric acid water (mass concentration of dichloropropanol is 35.00%), use 12.53 kg of dichloromethane × 3 to extract three times at room temperature, collect 50.47 kg of organic phase and 24.82 kg of aqueous phase, and quantitatively analyze by gas chromatography, the mass fraction of dichloropropanol in the organic phase is 25.68%, and the extraction rate of dichloropropanol is 98.50%.

[0042] Add the organic phase 1 to the cyclization reactor, start stirring and heat to 45° C. Weigh 4.20 kg of sodium hydroxide and 21.00 kg of water to prepare a sodium hydroxide aqueous solution, pump the alkali solution into the cyclization reactor, continue stirring and reacting for 15 minutes after adding, and the stirring speed is 120 r / min.

[0043] The reaction solution was transferred to a static kettle and allowed to stand for 25 minutes, and the organic phase 2 and the aqueous phase 2 were obtained by separation. The aqueous phase 2 was extracted three times with 3.00 kg of dichloromethane × 3, and the organic phase obtained by extraction was incorporated into the organic phase 2. The organic phase 2 was distilled under normal pressure to obtain 43.35 kg of dichloromethane (97.20% recovery rate), which was recycled as a solvent or extractant for the cyclization reaction and an extractant for the chlorination reaction, and 9.09 kg of epichlorohydrin (98.30% yield), and the residue in the distillation kettle was recovered as a raw material for the cyclization reaction.

[0044] Example 3

[0045] Weigh 37.60 kg of dichloropropanol hydrochloric acid water (mass concentration of dichloropropanol is 35.00%), extract three times with 12.53 kg of dichloroethane at room temperature, let stand for 20 min, collect 49.82 kg of organic phase and 25.35 kg of aqueous phase, and quantitatively analyze by gas chromatography, the mass fraction of dichloropropanol in the organic phase is 24.68%, and the extraction rate of dichloropropanol is 93.50%.

[0046] Add the organic phase 1 to the cyclization reactor, start stirring and heat to 70° C. Weigh 5.00 kg of sodium hydroxide and 20.00 kg of water to prepare a sodium hydroxide aqueous solution, pump the alkali solution into the cyclization reactor, continue stirring and reacting for 15 minutes after adding, and the stirring speed is 120 r / min.

[0047] The reaction solution was transferred to a standing kettle and allowed to stand for 25 minutes, and the organic phase 2 and the aqueous phase 2 were separated by stratification. The aqueous phase 2 was extracted three times with 4.00 kg of ethylene dichloride × 3, and the organic phase obtained by extraction was incorporated into the organic phase 2. The organic phase 2 was distilled under normal pressure to obtain 48.61 kg of ethylene dichloride (98.00% recovery rate), which was recycled as a solvent or extractant for the cyclization reaction and an extractant for the chlorination reaction, and 8.57 kg of epichlorohydrin (97.10% yield), and the residue in the distillation kettle was recovered as a raw material for the cyclization reaction.

[0048] Example 4

[0049] Weigh 37.60 kg of dichloropropanol hydrochloric acid water (mass concentration of dichloropropanol is 35.00%), extract three times with 12.53 kg of chloroform at room temperature, let stand for 20 min, collect 50.17 kg of organic phase and 24.83 kg of aqueous phase, and quantitatively analyze by gas chromatography, the mass fraction of dichloropropanol in the organic phase is 25.05%, and the extraction rate of dichloropropanol is 95.50%.

[0050] Add the organic phase 1 to the cyclization reactor, start stirring and heat to 60° C. Weigh 4.28 kg of sodium hydroxide and 25.00 kg of water to prepare a sodium hydroxide aqueous solution, pump the alkali solution into the cyclization reactor, continue stirring and reacting for 20 minutes after adding, and the stirring speed is 110 r / min.

[0051] The reaction solution was transferred to a standing kettle and allowed to stand for 230 minutes, and the organic phase 2 and the aqueous phase 2 were separated by stratification. The aqueous phase 2 was extracted twice with 6.00 kg of chloroform, and the organic phase obtained by extraction was incorporated into the organic phase 2. The organic phase 2 was distilled under normal pressure to obtain 48.86 kg of chloroform (98.50% recovery rate), which was recycled as a solvent or extractant for the cyclization reaction and an extractant for the chlorination reaction, and 8.57 kg of epichlorohydrin (95.10% yield), and the residue in the distillation kettle was recovered as a raw material for the cyclization reaction.

[0052] Example 5

[0053] Weigh 37.60 kg of dichloropropanol hydrochloric acid water (mass concentration of dichloropropanol is 35.00%), extract three times with 12.53 kg of carbon tetrachloride × 3 at room temperature, let stand for 20 min, collect 50.20 kg of organic phase and 24.92 kg of aqueous phase, and quantitatively analyze by gas chromatography, the mass fraction of dichloropropanol in the organic phase is 25.30%, and the extraction rate of dichloropropanol is 96.50%.

[0054] Add the organic phase 1 to the cyclization reactor, start stirring and heat to 40° C. Weigh 4.00 kg of sodium hydroxide and 24.00 kg of water to prepare a calcium hydroxide aqueous solution, pump the alkali solution into the cyclization reactor, continue stirring and reacting for 50 minutes after adding, and the stirring speed is 110 r / min.

[0055] The reaction solution was transferred to a static kettle and allowed to stand for 30 minutes, and the organic phase 2 and the aqueous phase 2 were obtained by stratification. The aqueous phase 2 was extracted three times with 5.00 kg of carbon tetrachloride × 3, and the organic phase obtained by extraction was incorporated into the organic phase 2. The organic phase 2 was distilled under normal pressure to obtain 50.81 kg of carbon tetrachloride (96.60% recovery rate), which was recycled as a solvent or extractant for the cyclization reaction and the extractant for the chlorination reaction, and 8.75 kg of epichlorohydrin (96.10% yield), and the residue in the distillation kettle was recovered as a raw material for the cyclization reaction.

[0056] Example 6

[0057] Weigh 37.60 kg of dichloropropanol hydrochloric acid water (mass concentration of dichloropropanol is 35.00%), extract three times with 12.53 kg of dichloroethane at room temperature, let stand for 20 min, collect 49.85 kg of organic phase and 25.30 kg of aqueous phase, and quantitatively analyze by gas chromatography, the mass fraction of dichloropropanol in the organic phase is 24.55%, and the extraction rate of dichloropropanol is 93.00%.

[0058] Add the organic phase 1 to the cyclization reactor, start stirring and heat to 50° C. Weigh 5.75 kg of sodium hydroxide and 23.00 kg of water to prepare a potassium hydroxide aqueous solution, pump the alkali solution into the cyclization reactor, continue stirring and reacting for 25 minutes after adding, and the stirring speed is 130 r / min.

[0059] The reaction solution was transferred to a static kettle and allowed to stand for 20 minutes, and the organic phase 2 and the aqueous phase 2 were separated by stratification. The aqueous phase 2 was extracted three times with 4.00 kg of ethylene dichloride × 3, and the organic phase obtained by extraction was incorporated into the organic phase 2. The organic phase 2 was distilled under normal pressure to obtain 47.86 kg of ethylene dichloride (96.50% recovery rate), which was recycled as a solvent or extractant for the cyclization reaction and an extractant for the chlorination reaction, and 8.45 kg of epichlorohydrin (96.30% yield), and the residue in the distillation kettle was recovered as a raw material for the cyclization reaction.

[0060] In other embodiments, the mass concentration of dichloropropanol in dichloropropanol hydrochloric acid water can be any value in the range of 32%-36%, such as 32%, 33%, 34%, 36%, and the dichloropropanol hydrochloric acid water can be extracted with an organic solvent twice. Figure 1 The gas phase spectrum of the dichloropropanol cyclization reaction liquid obtained by the method of the present invention shows that the dichloropropanol cyclization reaction of the present invention has high selectivity, only one product, epichlorohydrin, and no by-products such as monochloropropanol and glycerol, and has the advantages of mild reaction conditions, low energy consumption, simple process, high efficiency, etc.

[0061] Comparative Example 1

[0062] Weigh 37.60 kg of dichloropropanol hydrochloric acid water (mass concentration of dichloropropanol is 35.00%), extract three times with 12.53 kg of ethyl acetate × 3 at room temperature, let stand for 20 min, collect 43.14 kg of organic phase and 32.01 kg of aqueous phase, and quantitatively analyze by gas chromatography, the mass fraction of dichloropropanol in the organic phase is 12.96%, and the extraction rate of dichloropropanol is 42.50%.

[0063] Add the organic phase 1 to the cyclization reactor, start stirring and heat to 45° C. Weigh 1.87 kg of sodium hydroxide and 9.37 kg of water to prepare a sodium hydroxide aqueous solution, pump the alkali solution into the cyclization reactor, continue stirring and reacting for 15 minutes after adding, and the stirring speed is 120 r / min.

[0064] The reaction solution was transferred to a standing kettle and allowed to stand for 25 minutes, and the organic phase 2 and the aqueous phase 2 were separated by stratification. The aqueous phase 2 was extracted three times with 2.00 kg of ethyl acetate × 3, and the organic phase obtained by extraction was incorporated into the organic phase 2. The organic phase 2 was distilled under normal pressure to obtain 42.81 kg of ethyl acetate (98.20% recovery rate), which was recycled as a solvent or extractant for the cyclization reaction and the extractant for the chlorination reaction, and 3.65 kg of epichlorohydrin (91.00% yield), and the residue in the distillation kettle was recovered as a raw material for the cyclization reaction.

[0065] Although the present invention has been described in detail with reference to the accompanying drawings and in combination with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily think of changes or substitutions within the technical scope disclosed by the present invention, and these shall be within the scope of protection of the present invention.

Claims

1. A method for preparing epichlorohydrin, It is characterized in that The steps include: (1) At room temperature, extracting dichloropropanol hydrochloric acid water with an organic solvent, standing and stratifying to obtain an organic phase 1 and an aqueous phase 1, and collecting the organic phase 1; the organic solvent is one or more of dichloromethane, dichloroethylene, chloroform, and carbon tetrachloride; (2) transferring the organic phase into a cyclization reaction kettle, heating it to a set temperature, adding the prepared alkali solution into the cyclization reaction kettle under stirring, and stopping the reaction after a certain reaction time to obtain a cyclization reaction liquid; the set temperature of the cyclization reaction kettle is 30-70°C; The molar ratio of the organic phase 1 to the hydroxide in the alkali is 1:1.05-1.3, the reaction time is 10-60 min, and the stirring speed is 110-130 r / min; The organic solvent can act as a phase transfer agent to transfer the epichlorohydrin generated by the cyclization of dichloropropanol to the organic phase, thus preventing the ring-opening reaction of epichlorohydrin from occurring during long-term contact with water. (3) The cyclization reaction solution is transferred to a liquid separator and allowed to stand for stratification to obtain an organic phase II and an aqueous phase II. The aqueous phase II is extracted 2-3 times with an organic solvent, and the organic phase obtained by the extraction is incorporated into the organic phase II; (4) The organic phase 2 is transferred to a distillation tower for distillation to obtain epichlorohydrin, organic solvent and distillation still residue.

2. The preparation method according to claim 1, It is characterized in that The dichloropropane hydrochloride water in step (1) is an azeotropic condensate formed by dichloropropane, HCl and water, wherein the mass concentration of dichloropropane is 32%-36%.

3. The preparation method according to claim 1, It is characterized in that In step (1), the mass ratio of dichloropropane hydrochloride water to the organic solvent is 1:0.6-1.

4. The preparation method according to claim 1, It is characterized in that The alkali solution in step (2) is one or more of sodium hydroxide solution, potassium hydroxide solution, and calcium hydroxide solution, and the mass concentration of the alkali solution is 14% to 20%.

5. The preparation method according to claim 1, It is characterized in that The organic solvent in step (3) is one or more of dichloromethane, dichloroethane, chloroform, and carbon tetrachloride, and the standing time for stratification is 20 to 30 minutes.

6. The preparation method according to claim 1, It is characterized in that The distillation pressure in step (4) is normal pressure, and the organic solvent obtained by distillation is recycled as a solvent for the cyclization reaction or an extractant and an extractant for the chlorination reaction.

7. The preparation method according to claim 1, It is characterized in that The residue from the distillation still in step (4) is recovered and used as a raw material for the cyclization reaction in step (2).

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