A method for separating and purifying 3-chloropropene

Abstract

The present application relates to a kind of methods for separating and purifying 3-chloropropene.The method comprises the following steps: 1) the raw material chloropropene is separated by rectification to obtain refined chloropropene.2) the liquid in the tower pot enters the dimerization reactor to make 1,5-hexadiene polymerize.3) the polymerization reaction liquid is separated by rectification, and the light component is recycled into the chloropropene refining tower;The raw material chloropropene refining method of the present application described in the present application can reduce the content of 1,5-hexadiene in 3-chloropropene, improve the effect of epoxidation reaction;By increasing polymerization reaction, 1,5-hexadiene is effectively separated, and the consumption of 3-chloropropene in the chloropropene refining process is reduced.

Description

Technical Field

[0001] This invention belongs to the field of epichlorohydrin separation and recovery technology, specifically relating to a hydrogen peroxide method for refining epichlorohydrin raw material 3-chloropropene and a polymerization catalyst. Background Technology

[0002] Epichlorohydrin (ECH) is mainly used in the production of epoxy resins, glycerin, chlorohydrin rubber and other derivatives. It can also be used as a solvent, plasticizer, flame retardant and surfactant. It is an important organic chemical raw material and an important intermediate in petrochemicals, with a wide range of applications.

[0003] Epichlorohydrin is the epoxy monomer with the largest market capacity after EO and PO, with a global demand of 2.5 million tons per year. China's apparent consumption is approximately 900,000-1,000,000 tons per year, growing at a rate of 5%-6% annually. Epoxy resin, as the largest downstream product of epichlorohydrin, shows a strong positive correlation between consumption and economic development. Developed countries consume approximately 1.5 kg of epoxy resin per capita, while China's per capita consumption is only 0.9 kg, indicating significant potential for the development of the Chinese epoxy resin market. Among the current mainstream epichlorohydrin production processes, the hydrogen peroxide process is the most researched due to its environmental friendliness and its status as an innovative process encouraged by the government.

[0004] Chinese patent CN 201110319618.0 discloses a method for purifying epichlorohydrin containing olefin impurities. To eliminate the difficult-to-separate impurity 1,2-epoxy-5-hexene in the product, halogen is introduced into the crude epichlorohydrin after allyl chloride separation. This causes the 1,2-epoxy-5-hexene impurity to undergo addition reactions with other high-boiling-point substances, increasing the boiling point difference between 1,2-epoxy-5-hexene and epichlorohydrin, which are then separated using conventional separation methods. While this method can efficiently remove the 1,2-epoxy-5-hexene impurity from epichlorohydrin, it introduces a relatively large amount of halogen, increasing raw material costs, significantly enhancing corrosiveness, and making operation more difficult.

[0005] Chinese patent CN 201480022879.8 describes a method for removing 1,2-epoxy-5-hexene from epichlorohydrin. This patent also involves adding halogen to convert 1,2-epoxy-5-hexene into other addition products. The patent controls the molar ratio of halogen to 1,2-epoxy-5-hexene at 0.5-1:1 to minimize the 1,2-epoxy-5-hexene content in the product. However, this patent, which also relies on adding halogen to reduce the 1,2-epoxy-5-hexene content, cannot completely avoid the problems of raw material costs and corrosiveness.

[0006] The hydrogen peroxide method for epichlorohydrin production involves three steps: high-temperature chlorination of propylene to produce allyl chloride; a cyclization reaction of allyl chloride and hydrogen peroxide in the presence of a catalyst to generate epichlorohydrin; and epichlorohydrin separation and purification. During the high-temperature chlorination of propylene to produce allyl chloride, 1,5-hexadiene is generated as a byproduct with a content >1000 ppm. This byproduct undergoes a cyclization reaction to generate 1,2-epoxy-5-hexene, which has the same boiling point as epichlorohydrin and cannot be separated by distillation. High-quality epichlorohydrin requires a content >99.9%, but when the 1,5-hexadiene content in the raw material is >1000 ppm, high-quality epichlorohydrin cannot be obtained, affecting downstream applications. Therefore, developing a suitable separation method to address the formation of 1,5-hexadiene is crucial for obtaining high-quality epichlorohydrin. Summary of the Invention

[0007] This invention addresses the problem of high 1,5-hexadiene content affecting product purity in the hydrogen peroxide-based epichlorohydrin process by developing a method for separating and purifying 3-chloropropene. The method achieves 3-chloropropene purification through distillation and polymerization. First, conventional distillation is used to initially separate 1,5-hexadiene at a relatively low temperature, reducing the loss of 3-chloropropene.

[0008] The present invention also provides a selective polymerization catalyst for 1,5-hexadiene, which can achieve highly selective polymerization of 1,5-hexadiene, further improve the dechlorination of 1,5-hexadiene in the raw materials, and reduce the consumption of 3-chloropropene.

[0009] To achieve the above-mentioned objectives, the technical solution of the present invention is as follows:

[0010] A method for separating and purifying 3-chloropropene includes the following steps:

[0011] 1) The 3-chloropropene feedstock is purified by the first purification column to obtain the overhead liquid and the bottom liquid. The overhead liquid is crude 3-chloropropene. The 1,5-hexadiene content in the epoxidized feedstock 3-chloropropene is reduced by the first distillation column.

[0012] 2) Crude 3-chloropropene is introduced into the polymerization reactor. In the presence of the polymerization catalyst, 1,5-hexadiene undergoes a dimerization reaction, converting 1,5-hexadiene into a dimer. Due to the steric hindrance effect of chlorine, the conversion rate of 3-chloropropene is extremely low.

[0013] 3) The dimerization reaction liquid is separated in the second distillation column to obtain the bottom liquid and the top liquid. The bottom liquid has a high content of 1,5-hexadiene dimer. Part of it is recycled back to the feed inlet of the first distillation column to recover 3-chloropropene, and part of it is treated as waste liquid. The top liquid is 3-chloropropene with a low content of 1,5-hexadiene after purification.

[0014] In step 1) of this invention, the content of 1,5-hexadiene in the 3-chloropropene raw material is 500-5000 ppm.

[0015] In step 1) of this invention, the first refining column is an atmospheric distillation operation, the bottom temperature of the distillation column is 60-80℃, the top temperature of the distillation column is 35-52℃, the theoretical number of separation plates is 30-50, and the reflux ratio is 0.5-2.5.

[0016] In step 2) of this invention, the dimerization reaction temperature is 80-120℃, the pressure is 1-3.5 MPa, and the reaction solution throughput is 0.3-1.5 h. -1 .

[0017] In step 3) of the present invention, the second refining column is an atmospheric distillation column, the bottom temperature of the distillation column is 70-100℃, the top temperature of the distillation column is 35-50℃, the theoretical separation plate number is 15-30, and the reflux ratio is 0.5-2.0.

[0018] In step 2) of this invention, the method for preparing the polymerization catalyst includes the following steps:

[0019] 1) Place ZSM-5 in an aqueous solution of oxalic acid and nickel oxalate, and then place it in a crystallization kettle. Crystallize at 110-140℃ for 48 hours to obtain the carrier.

[0020] 2) Add nickel salt, copper salt and zirconium salt to deionized water to prepare a 0.5-1.5M salt solution for later use;

[0021] 3) The carrier is immersed in a salt solution, and the immersion solution is adsorbed in a crystallization kettle at 120-150℃. Then, it is aged at 120-150℃ for 4-6 hours, and then further aged at 150-180℃ for 4-6 hours. After filtration, it is dried.

[0022] This method can reduce the content of 1,5-hexadiene in 3-chloropropene to <200 ppm, and preferably reduce the content of 1,5-hexadiene to <100 ppm.

[0023] In step 2) of this invention, the nickel salt is selected from one or more of nickel nitrate, nickel carbonate, nickel acetate and nickel oxalate.

[0024] In step 2) of this invention, the copper salt is selected from one or more of copper nitrate, copper chloride, copper acetate, and copper sulfate.

[0025] In step 2) of this invention, the zirconium salt is selected from one or more of zirconium nitrate, zirconium oxychloride, zirconium acetate, or zirconium sulfate.

[0026] In step 1) of this invention, the amount of nickel oxalate used is 1-3 wt%, based on the weight of the catalyst.

[0027] The dimerizing catalyst of the present invention comprises the following components: nickel oxide 5-15 wt%; zirconium oxide 1-5 wt%; copper oxide 2-8 wt%, based on the weight of the catalyst.

[0028] The polymerization catalyst is expanded and modified by nickel oxalate and oxalic acid. After modification, the internal pores of the catalyst are larger. After nickel oxalate is loaded into the catalyst pores, the binding force between the salt and the support inside the pores can be effectively increased during the subsequent impregnation process. Furthermore, the addition of zirconium additive can further improve the polymerization reaction activity. While increasing the diffusion rate, the high-selectivity polymerization of 1,5-hexadiene is achieved, and the removal of 1,5-hexadiene is effectively realized.

[0029] The method of this invention can effectively reduce the 1,5-hexadiene content in 3-chloropropene. First, 3-chloropropene is concentrated and enriched in a first distillation column under relatively low distillation conditions. Then, 3-chloropropene and 1,5-hexadiene are separated under milder conditions, reducing separation energy consumption. Subsequently, a polymer catalyst is creatively used to selectively polymerize 1,5-hexadiene. The pore-expansion effect during molecular sieve crystallization and impregnation increases the catalyst pore size, accelerating the diffusion rate of 1,5-hexadiene. Furthermore, the initial loading of nickel oxalate effectively increases the binding force between the salt and the internal support during subsequent impregnation. The addition of zirconium additive further enhances the polymerization activity, resulting in highly selective polymerization of 1,5-hexadiene. Finally, the 1,5-hexadiene polymer and 3-chloropropene are further separated in a second distillation column, increasing the yield of 3-chloropropene during the separation process.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] 1) The separation method of this invention can obtain 3-chloropropene with low 1,5-hexadiene impurity content, which not only improves the epoxidation reaction activity, but also eliminates the need for further separation of 1,2-epoxy-5-hexene in the product after the epoxidation reaction, thus obtaining a superior grade of epichlorohydrin.

[0032] 2) A selective polymerization reaction was creatively introduced and used in conjunction with distillation separation. When the concentration of 1,5-hexadiene in the bottom liquid of the column increases, a specially treated molecular sieve is used to selectively react 1,5-hexadiene to generate a dimer, thereby increasing the boiling point of the 1,5-hexadiene dimer and 3-chloropropene, further recovering 3-chloropropene from the bottom liquid and improving the recovery rate of 3-chloropropene in the purification process. Detailed Implementation

[0033] To better understand the technical solution of the present invention, the following embodiments will further illustrate the method provided by the present invention. However, the present invention is not limited to the listed embodiments, but should also include any other well-known modifications within the scope of the claims of the present invention.

[0034] Chromatographic analysis conditions: Analysis was performed using a PONA (30m × 0.25mm × 0.25μm) column. Specific operating conditions were: 50℃ for 2 minutes, then increased to 200℃ at a rate of 15℃ / min and held for 5 minutes. The injector temperature was 220℃, and the detector temperature was 240℃.

[0035] The methanol is produced by the company's methanol plant, and the product purity is >99.5%.

[0036] Allyl chloride is supplied by Aladdin Reagent Co., Ltd., and the product purity is >99%.

[0037] Nickel sulfate was supplied by Xilong Chemical Reagent Co., Ltd., and the product purity is >98%.

[0038] Copper nitrate trihydrate is supplied by Xilong Chemical Co., Ltd., and the product purity is >98%.

[0039] Zirconium nitrate pentahydrate was supplied by Xilong Chemical Reagent Co., Ltd., with a purity >98%.

[0040] The ammonia solution was supplied by Xilong Chemical Reagent Co., Ltd., with a purity of 25-28%.

[0041] ZSM-5 was supplied by China Catalyst Co., Ltd.

[0042] Example 1

[0043] Dissolve 1.97g of nickel oxalate and 16.80g of oxalic acid in 500ml of water, place 91g of ZSM-5 in the prepared oxalic acid / nickel oxalate aqueous solution, and place it in a rotary crystallizer for crystallization treatment at 110℃ for 48h.

[0044] Weigh 19.52g of nickel nitrate hexahydrate, 2.62g of zirconium oxychloride octahydrate, and 6.04g of copper nitrate trihydrate, dissolve them in 200.5g of water to prepare a 0.5M salt solution, mix well and set aside.

[0045] After crystallization, the support was placed in a rotatable crystallization vessel. A 0.5M salt solution was poured into the crystallization vessel. The impregnation solution was evenly adsorbed onto the surface of the support by turning the vessel. After the catalyst was matured at 120℃ for 6 hours, the temperature was raised to 150℃ for 6 hours for further crystallization. After drying at 120℃ for 4 hours, polymerization catalyst A was obtained.

[0046] Example 2

[0047] Dissolve 3.94g of nickel oxalate and 15.59g of oxalic acid in 500ml of water, place 80g of ZSM-5 in the prepared oxalic acid / nickel oxalate aqueous solution, and place it in a rotary crystallization kettle for crystallization treatment at 125℃ for 48h.

[0048] Weigh out 39.03g of nickel nitrate hexahydrate, 7.86g of zirconium oxychloride octahydrate, and 15.1g of copper nitrate trihydrate, dissolve them in 291.8g of water to prepare a 0.75M salt solution, mix thoroughly and set aside.

[0049] After crystallization, the support was placed in a rotatable crystallization vessel. A 0.75M salt solution was poured into the crystallization vessel. The impregnation solution was evenly adsorbed onto the surface of the support by turning the vessel. After the catalyst was matured at 135℃ for 5 hours, the temperature was raised to 165℃ for 5 hours for further crystallization. Finally, it was dried at 120℃ for 4 hours to obtain polymerization catalyst B.

[0050] Example 3

[0051] Dissolve 5.91g of nickel oxalate and 14.38g of oxalic acid in 500ml of water, place 65g of ZSM-5 in the prepared oxalic acid / nickel oxalate aqueous solution, and place it in a rotary crystallizer for crystallization treatment at 140℃ for 48h.

[0052] Weigh out 58.55g of nickel nitrate hexahydrate, 13.1g of zirconium oxychloride octahydrate, and 24.16g of copper nitrate trihydrate, dissolve them in 342.0g of water to prepare a 1.0M salt solution, mix well and set aside.

[0053] After crystallization, the support was placed in a rotatable crystallization vessel. A 1.0M salt solution was poured into the crystallization vessel. The impregnation solution was evenly adsorbed onto the surface of the support by turning the vessel. After the catalyst was matured at 150℃ for 4 hours, the temperature was raised to 180℃ for 4 hours for further crystallization. Finally, it was dried at 120℃ for 4 hours to obtain polymerization catalyst C.

[0054] Example 4

[0055] Crude 3-chloropropene feedstock with a 1,5-hexadiene content of 1560 ppm is fed into the first distillation column. The bottom temperature of the first distillation column is 60°C, the top temperature is 39°C, the theoretical number of plates is 50, and the reflux ratio is 0.5. The top of the distillation column contains purified crude chloropropene, which is sent to the dimerization reactor. The 1,5-hexadiene content in the crude chloropropene is reduced to 815 ppm. The bottom liquid is discharged as waste liquid.

[0056] The dimerization reactor uses catalyst A, the reaction temperature is 80℃, the reaction pressure is 3.5 MPa, and the reaction liquid throughput is 0.3 h⁻¹. -1 The dimerization reaction liquid enters the second distillation column.

[0057] The second distillation column has a bottom temperature of 70°C, a top temperature of 41°C, a theoretical plate number of 15, and a reflux ratio of 0.5. The overhead liquid is purified 3-chloropropene, with the 1,5-hexadiene content reduced to 85 ppm. One-third of the bottom liquid is discharged as waste, and two-thirds is recycled back to the inlet of the first distillation column to recover 3-chloropropene.

[0058] Example 5

[0059] Crude 3-chloropropene feedstock with a 1,5-hexadiene content of 1560 ppm was fed into the first distillation column. The bottom temperature of the first distillation column was 70°C, the top temperature was 40°C, the theoretical number of plates was 40, and the reflux ratio was 1.5. The top of the distillation column contained purified crude 3-chloropropene, which was then sent to the dimerization reactor. The 1,5-hexadiene content in the crude 3-chloropropene was reduced to 862 ppm. The bottom liquid was discharged as waste. The dimerization reactor used catalyst B, with a reaction temperature of 100°C, a reaction pressure of 2.0 MPa, and a reaction volume of 1.0 h⁻¹. -1 The dimerization reaction liquid enters the second distillation column.

[0060] The second distillation column has a bottom temperature of 85°C, a top temperature of 42°C, a theoretical plate number of 25, and a reflux ratio of 1.0. The overhead liquid is purified 3-chloropropene, with the 1,5-hexadiene content reduced to 92 ppm. One-third of the bottom liquid is discharged as waste, and two-thirds is recycled back to the inlet of the first distillation column to recover 3-chloropropene.

[0061] Example 6

[0062] Crude 3-chloropropene feedstock with a 1,5-hexadiene content of 1560 ppm was fed into the first distillation column. The bottom temperature of the first distillation column was 80°C, the top temperature was 42°C, the theoretical number of plates was 30, and the reflux ratio was 2.5. The top of the distillation column contained purified crude chloropropene, which was then sent to the dimerization reactor. The 1,5-hexadiene content in the crude chloropropene was reduced to 877 ppm. The bottom liquid was discharged as waste. The dimerization reactor used catalyst C, with a reaction temperature of 120°C, a reaction pressure of 1.0 MPa, and a reaction volume of 1.5 h⁻¹. -1 The dimerization reaction liquid enters the second distillation column.

[0063] The second distillation column has a bottom temperature of 100°C, a top temperature of 43°C, a theoretical number of plates of 35, and a top reflux ratio of 2.0.

[0064] The overhead liquid is refined 3-chloropropene, with the 1,5-hexadiene content reduced to 99 ppm. One-third of the bottom liquid is discharged as waste liquid, and two-thirds is recycled back to the inlet of the first distillation column to recover 3-chloropropene.

[0065] Comparative Example 1

[0066] A distillation column was used to process crude 3-chloropropene feedstock with a 1,5-hexadiene content of 1700 ppm. The column bottom temperature was 80°C, the top temperature was 42°C, the theoretical number of plates was 30, and the reflux ratio was 2.5. The purified chloropropene at the top of the distillation column was sent to the epoxidation unit. The 1,5-hexadiene content in the purified chloropropene was reduced to 800 ppm. Subsequently, it entered the epoxidation reactor, where the 1,2-epoxy-5-hexene concentration was 830 ppm. Through the separation process, epichlorohydrin was obtained with a purity of only 99.8%, which was insufficient to obtain a high-grade epichlorohydrin.

[0067] Comparative Example 2

[0068] Weigh out 58.55g of nickel nitrate hexahydrate, 13.1g of zirconium oxychloride octahydrate, and 24.16g of copper nitrate trihydrate, dissolve them in 342.0g of water to prepare a 1.0M salt solution, mix well and set aside.

[0069] 65g of ZSM-5 support was placed in a rotating crystallization vessel, and a 1.0M salt solution was poured into the crystallization vessel. The impregnation solution was evenly adsorbed onto the surface of the support by turning the vessel. After the catalyst was matured at 150℃ for 4 hours, the temperature was raised to 180℃ for 4 hours for further crystallization, and then dried at 120℃ for 4 hours to obtain polymerization catalyst D.

[0070] Crude 3-chloropropene feedstock with a 1,5-hexadiene content of 1560 ppm was fed into the first distillation column. The bottom temperature of the first distillation column was 80°C, the top temperature was 42°C, the theoretical number of plates was 30, and the reflux ratio was 2.5. The top of the distillation column contained purified crude chloropropene, which was then sent to the dimerization reactor. The 1,5-hexadiene content in the crude chloropropene was reduced to 877 ppm. The bottom liquid was discharged as waste. The dimerization reactor used catalyst D, with a reaction temperature of 120°C, a reaction pressure of 1.0 MPa, and a reaction volume of 1.5 h⁻¹. -1 The dimerization reaction liquid enters the second distillation column.

[0071] The second distillation column has a bottom temperature of 100°C, a top temperature of 43°C, a theoretical number of plates of 35, and a top reflux ratio of 2.0.

[0072] The overhead liquid is refined 3-chloropropene, with the 1,5-hexadiene content reduced to 670 ppm. One-third of the bottom liquid is discharged as waste liquid, and two-thirds is recycled back to the inlet of the first distillation column to recover 3-chloropropene.

[0073] Comparative Example 3

[0074] Weigh 58.55g of nickel nitrate hexahydrate and 24.16g of copper nitrate trihydrate, dissolve them in 342.0g of water to make a 1.0M salt solution, mix well and set aside.

[0075] 65g of ZSM-5 support was placed in a rotating crystallization vessel, and a 1.0M salt solution was poured into the crystallization vessel. The impregnation solution was evenly adsorbed onto the surface of the support by turning the vessel. After the catalyst was matured at 150℃ for 4 hours, the temperature was raised to 180℃ for 4 hours for further crystallization, and then dried at 120℃ for 4 hours to obtain polymerization catalyst E.

[0076] Crude 3-chloropropene feedstock with a 1,5-hexadiene content of 1560 ppm was fed into the first distillation column. The bottom temperature of the first distillation column was 80°C, the top temperature was 42°C, the theoretical number of plates was 30, and the reflux ratio was 2.5. The top of the distillation column contained purified crude 3-chloropropene, which was then sent to the dimerization reactor. The 1,5-hexadiene content in the crude 3-chloropropene was reduced to 877 ppm. The bottom liquid was discharged as waste. The dimerization reactor used catalyst E, with a reaction temperature of 120°C, a reaction pressure of 1.0 MPa, and a reaction volume of 1.5 h⁻¹. -1 The dimerization reaction liquid enters the second distillation column.

[0077] The second distillation column has a bottom temperature of 100°C, a top temperature of 43°C, a theoretical number of plates of 35, and a top reflux ratio of 2.0.

[0078] The overhead liquid is refined 3-chloropropene, with the 1,5-hexadiene content reduced to 620 ppm. One-third of the bottom liquid is discharged as waste liquid, and two-thirds is recycled back to the inlet of the first distillation column to recover 3-chloropropene.

Claims

1. A method for separating and purifying 3-chloropropene, comprising the steps of: 1) purifying 3-chloropropene raw material by using a first rectifying column to obtain a column top liquid and a column bottom liquid, the column top liquid being crude 3-chloropropene; 2) introducing the crude 3-chloropropene into a polymerization reactor, and allowing 1,5-hexadiene to undergo dimerization in the presence of a polymerization catalyst; 3) separating the dimerization liquid in a second rectifying column to obtain a column bottom liquid and a column top liquid, part of the column bottom liquid being recycled back to the feed inlet of the first rectifying column to recover 3-chloropropene, and part being treated as waste liquid, the column top liquid being 3-chloropropene with low 1,5-hexadiene content; wherein in the step 2), the polymerization catalyst is prepared by the steps of: 1) placing ZSM-5 in oxalic acid and aqueous nickel oxalate solution, and placing in a crystallization kettle, and performing crystallization treatment at 110-140℃ for 48h to obtain a carrier; 2) adding nickel salt, copper salt and zirconium salt into deionized water to prepare a 0.5-1.5M salt solution for standby; 3) immersing the carrier in the salt solution, adsorbing and immersing the liquid in a crystallization kettle at 120-150℃, then aging at 120-150℃ for 4-6h, and further aging at 150-180℃ for 4-6h, filtering and drying. In the step 1), the 1,5-hexadiene raw material content in the 3-chloropropene raw material is 500-5000ppm. In the step 1), the first rectifying column is operated under normal pressure, the column bottom temperature of rectification separation is 60-80℃, the column top temperature of rectification separation is 35-52℃, the theoretical separation plate number is 30-50, and the reflux ratio is 0.5-2.

5. In the step 3), the second rectifying column is operated under normal pressure, the column bottom temperature of rectification separation is 70-100℃, the column top temperature of rectification separation is 35-50℃, the theoretical separation plate number is 15-30, and the reflux ratio is 0.5-2.

0. The polymerization catalyst comprises the following components: 5-15wt% of nickel oxide, 1-5wt% of zirconium oxide, and 2-8wt% of copper oxide, based on the weight of the catalyst. ​ ​ ​ 2. The method of claim 1, wherein, ​ 3. The method of claim 1, wherein, ​ 4. The method of claim 1, wherein, In the step 2), the dimerization temperature is 80-120℃, the pressure is 1-3.5Mpa, and the reaction liquid treatment amount is 0.3-1.5h -1 .

5. The method of claim 1, wherein, ​ 6. The method of claim 1, wherein, ​