A process for the preparation of epichlorohydrin

Abstract

The present application relates to a kind of preparation methods of epichlorohydrin, comprising the following steps: using two-stage fixed bed series reaction process, first reactor lower inlet upper outlet, second reactor upper inlet lower outlet;Chloropropene, hydrogen peroxide and organic acid from first reactor, the first reactor discharge and basic material into second reactor.By increasing the residence time in the first reactor, the conversion rate of hydrogen peroxide in the first reactor is increased, and the use of basic additives in the second reactor can reduce the acidity, increase the feed line speed, reduce the residence time, and reduce the amount of byproduct generation.The synthesis method of epichlorohydrin described in the present application can maintain high hydrogen peroxide conversion rate and epichlorohydrin selectivity, and has longer catalyst running life.

Description

Technical Field

[0001] This invention belongs to the field of epichlorohydrin production technology, specifically relating to a hydrogen peroxide method for synthesizing epichlorohydrin. 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 CN200710120615.8 discloses a titanium-silicon molecular sieve catalyst and its forming method. The raw material 3-chloropropene and an aqueous hydrogen peroxide solution are reacted with methanol in the presence of a solvent to produce epichlorohydrin via an epoxidation reaction. The reaction conditions described in this patent are as follows: the reaction is carried out in a jacketed tube fixed-bed reactor, with ammonia added as an alkaline additive. The reaction temperature is gradually increased from 50°C to 72°C at a heating rate of 0.04-0.08°C / hour. The hydrogen peroxide conversion rate is 98.4%, the average epichlorohydrin selectivity is 95.9%, and the longest single-pass reaction time reaches 466 hours.

[0005] Chinese patent CN202010992565.8 discloses a continuous synthesis process for epichlorohydrin using hydrogen peroxide. This synthesis process uses a ring reactor with the catalyst pre-loaded into the reactor. This process can achieve continuous operation, reduce the use and recovery of methanol, and eliminate the need for catalyst recovery. However, this process cannot reduce catalyst wear, resulting in increased catalyst loss.

[0006] As the hydrogen peroxide-based epichlorohydrin process increases with operating time, the reaction temperature needs to be continuously increased to ensure the hydrogen peroxide conversion rate. Furthermore, the continuous generation of oligomers blocks the catalyst pores, causing a significant decrease in catalyst activity. Further increasing the reaction temperature leads to a significant increase in etherification byproducts, resulting in a decrease in epichlorohydrin yield and impacting the long-term operation of the catalyst.

[0007] Therefore, it is particularly important to develop a simple, easy-to-implement, long-cycle, and highly active hydrogen peroxide-based epichlorohydrin process. Summary of the Invention

[0008] To address the low activity and susceptibility to catalyst deactivation in existing processes, a method for preparing epichlorohydrin has been developed. Using the method described in this invention, a high hydrogen peroxide conversion rate is achieved at a relatively low temperature. The synthesis method described in this invention employs a two-stage reactor connected in series. The first stage reactor operates at a lower temperature, while the second stage reactor incorporates an alkaline auxiliary agent. This synthesis method exhibits higher epichlorohydrin selectivity, significantly reduced byproduct formation, and a longer catalyst lifespan.

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

[0010] A method for preparing epichlorohydrin includes the following steps: employing a two-stage fixed-bed reaction process in series, with the first reactor having bottom-inlet and top-outlet, and the second reactor having top-inlet and bottom-outlet; allyl chloride, hydrogen peroxide, and organic acids enter from the first reactor, and the effluent from the first reactor and alkaline substances enter the second reactor.

[0011] The residence time in the first reactor is increased to increase the hydrogen peroxide conversion rate, while the feed line velocity in the second reactor is increased to reduce the residence time and reduce the amount of by-products generated.

[0012] The synthesis method of the present invention involves loading a catalyst into a two-stage fixed-bed reactor, wherein the catalyst is TS-1 molecular sieve produced by Nankai Molecular Sieve Catalyst Plant.

[0013] The synthesis method described in this invention uses a bottom-in, top-out feeding method, which helps to remove any oxygen that may be generated from the reactor. A vent valve is designed at the connection point of the two reactors at their highest points to release any inert gases that may be generated, thus eliminating potential safety risks.

[0014] The synthesis method of the present invention involves adding a small amount of organic acid at the inlet of the first reactor. The organic acid is selected from one of benzenesulfonic acid, methanesulfonic acid, ethanesulfonic acid, o-toluenesulfonic acid, and p-toluenesulfonic acid. The amount added is 10-150 ppm, based on the feed amount of the reaction liquid in the first reactor.

[0015] The synthesis method described in this invention uses a first reactor with a reaction temperature of 20-60℃ and a pressure of 0-1 MPa.

[0016] The molar ratio of allyl chloride to hydrogen peroxide in the feed to the first reactor is 1.5-5:1.

[0017] The first reactor is fed with methanol as a solvent, and the molar ratio of methanol to hydrogen peroxide is 4-8:1.

[0018] The alkaline substance described in this invention is selected from one or more of ammonia, trimethylamine, N-methylaniline, N-ethylaniline, and 2,6-diethylaniline. The pH of the feed to the second reactor is controlled at 6-7.5 by adding the alkaline substance.

[0019] In the synthesis method described in this invention, the reaction temperature of the second reactor is 30-70℃ and the pressure is 0-1 MPa.

[0020] The molar ratio of allyl chloride to hydrogen peroxide in the feed to the second reactor is 2.5-10:1.

[0021] The second reactor uses methanol as a solvent. The solvent is added to the second reactor, and the molar ratio of methanol to hydrogen peroxide is 12-30:1.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1) The first reactor adopts a bottom-in, top-out feeding method, which can maintain a high hydrogen peroxide conversion rate with a lower methanol usage.

[0024] 2) Adding organic acids to the first reactor can increase the hydrogen peroxide conversion rate at a lower reaction temperature. Low temperature is beneficial to reduce the formation of etherification byproducts.

[0025] 3) The second reactor adopts a top-in, bottom-out feeding method, and increases the amount of solvent methanol and adds alkaline additives. Under neutral conditions and at a higher linear velocity, the reaction can suppress the formation of etherification byproducts, improve the epichlorohydrin yield and extend the catalyst life.

[0026] 4) The first reactor adopts a bottom-in, top-out feed design, and an vent valve is designed at the high point to prevent hydrogen peroxide decomposition and oxygen production from reaching the explosion limit, thus ensuring the safety of the reaction. Detailed Implementation

[0027] 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.

[0028] 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℃.

[0029] The methanol is produced by the company's methanol plant, and the product purity is >99.5%.

[0030] Allyl chloride is supplied by Aladdin Reagent Co., Ltd., and the product purity is >99%.

[0031] The hydrogen peroxide was supplied by Inokai Reagent Co., Ltd., with a purity of 50%.

[0032] The organic acids are supplied by Beijing Inokai Technology Co., Ltd., and the product purity is >99%.

[0033] The alkaline additive was provided by Beijing Inokai Technology Co., Ltd., and the product purity is 99%.

[0034] Example 1

[0035] 100g of TS-1 catalyst was loaded, divided into two sections of 50g each. The reactor operated with a bottom-in, top-out feed configuration. The molar ratio of allyl chloride to hydrogen peroxide was 2, and the molar ratio of methanol to hydrogen peroxide was 4. The reaction pressure was 0.3 MPa. Benzenesulfonic acid was added at the inlet at a rate of 10 ppm, based on the total mass of the feed. The initial temperature was 20°C.

[0036] The secondary reactor operates using a top-in, bottom-out feeding method. The molar ratio of allyl chloride to hydrogen peroxide in the feed is 2.7, and the molar ratio of methanol to hydrogen peroxide in the feed is 13.3. The reaction pressure is 0.3 MPa, and ammonia is added at the inlet to control the feed pH at 6.5. The initial temperature is 30°C.

[0037] During the continuous reaction process, the conversion rate of hydrogen peroxide is increased by raising the reaction temperature of the first and second reactions, ensuring that the conversion rate of hydrogen peroxide is >97%.

[0038] The activity and stability of the catalyst were evaluated by different operating times, as shown in Table 1.

[0039] Table 1 Catalyst activity at different reaction times

[0040]

[0041] Example 2

[0042] 100g of TS-1 catalyst was loaded, divided into two sections of 50g each. The reactor operated with a bottom-in, top-out feed configuration. The molar ratio of allyl chloride to hydrogen peroxide was 2.5, and the molar ratio of methanol to hydrogen peroxide was 4. The reaction pressure was 0.5 MPa. Methanesulfonic acid was added at the inlet at a rate of 30 ppm, based on the total mass of the feed. The initial temperature was 20°C.

[0043] The secondary reactor operates using a top-in, bottom-out feeding method. The molar ratio of allyl chloride to hydrogen peroxide in the feed is 3.7, and the molar ratio of methanol to hydrogen peroxide in the feed is 14.5. The reaction pressure is 0.5 MPa, and trimethylamine is added at the inlet. The feed pH is controlled at 6.0. The initial temperature is 30°C.

[0044] During the continuous reaction process, the conversion rate of hydrogen peroxide is increased by raising the reaction temperature of the first and second reactions, ensuring that the conversion rate of hydrogen peroxide is >97%.

[0045] The activity and stability of the catalyst were evaluated by different operating times, as shown in Table 2.

[0046] Table 2 Catalyst activity at different reaction times

[0047]

[0048] Example 3

[0049] 100g of TS-1 catalyst was loaded, divided into two sections of 50g each. The reactor operated with a bottom-in, top-out feed configuration. The molar ratio of allyl chloride to hydrogen peroxide was 3.0, and the molar ratio of methanol to hydrogen peroxide was 6.0. The reaction pressure was 0.5 MPa. Ethylene sulfonic acid was added at the inlet at a rate of 50 ppm, based on the total mass of the feed. The initial temperature was 20°C.

[0050] The secondary reactor operates using a top-in, bottom-out feeding method. The molar ratio of allyl chloride to hydrogen peroxide in the feed is 5.0, and the molar ratio of methanol to hydrogen peroxide in the feed is 20.0. The reaction pressure is 0.5 MPa, and N-methylaniline is added at the inlet. The feed pH is controlled at 7.0. The initial temperature is 30°C.

[0051] During the continuous reaction process, the conversion rate of hydrogen peroxide is increased by raising the reaction temperature of the first and second reactions, ensuring that the conversion rate of hydrogen peroxide is >97%.

[0052] The activity and stability of the catalyst were evaluated by different operating times, as shown in Table 3.

[0053] Table 3 Catalyst activity at different reaction times

[0054]

[0055] Example 4

[0056] 100g of TS-1 catalyst was loaded, divided into two sections of 50g each. The reactor operated with a bottom-in, top-out feed configuration. The molar ratio of allyl chloride to hydrogen peroxide was 3.5, and the molar ratio of methanol to hydrogen peroxide was 6.0. The reaction pressure was 0.7 MPa. O-toluenesulfonic acid was added at the inlet at a rate of 100 ppm, based on the total mass of the feed. The initial temperature was 20°C.

[0057] The secondary reactor operates using a top-in, bottom-out feeding method. The molar ratio of allyl chloride to hydrogen peroxide in the feed is 6.5, and the molar ratio of methanol to hydrogen peroxide in the feed is 22.2. The reaction pressure is 0.7 MPa, and N-ethylaniline is added at the inlet. The feed pH is controlled at 7.5. The initial temperature is 30°C.

[0058] During the continuous reaction process, the conversion rate of hydrogen peroxide is increased by raising the reaction temperature of the first and second reactions, ensuring that the conversion rate of hydrogen peroxide is >97%.

[0059] The activity and stability of the catalyst were evaluated by different operating times, as shown in Table 4.

[0060] Table 4 Catalyst activity at different reaction times

[0061]

[0062] Example 5

[0063] 100g of TS-1 catalyst was loaded, divided into two sections of 50g each. The reactor operated with a bottom-in, top-out feed configuration. The molar ratio of allyl chloride to hydrogen peroxide was 4.5, and the molar ratio of methanol to hydrogen peroxide was 8.0. The reaction pressure was 1.0 MPa. 150 ppm of p-toluenesulfonic acid was added at the inlet, based on the total mass of the feed. The initial temperature was 20°C.

[0064] The secondary reactor operates using a top-in, bottom-out feeding method. The molar ratio of allyl chloride to hydrogen peroxide in the feed is 9.8, and the molar ratio of methanol to hydrogen peroxide in the feed is 30.0. The reaction pressure is 1.0 MPa. 2,6-Diethylaniline is added at the inlet, and the feed pH is controlled at 6.5. The initial temperature is 30°C.

[0065] During the continuous reaction process, the conversion rate of hydrogen peroxide is increased by raising the reaction temperature of the first and second reactions, ensuring that the conversion rate of hydrogen peroxide is >97%.

[0066] The activity and stability of the catalyst were evaluated by different operating times, as shown in Table 5.

[0067] Table 5 Catalyst activity at different reaction times

[0068]

[0069] Example 6

[0070] 100g of TS-1 catalyst was loaded, divided into two sections of 50g each. The reactor operated with a bottom-in, top-out feed configuration. The molar ratio of allyl chloride to hydrogen peroxide was 5.0, and the molar ratio of methanol to hydrogen peroxide was 8.0. The reaction pressure was 0.5 MPa. Benzenesulfonic acid was added at the inlet at a rate of 30 ppm, based on the total feed mass. The initial temperature was 20°C.

[0071] The secondary reactor operates using a top-in, bottom-out feeding method. The molar ratio of allyl chloride to hydrogen peroxide in the feed is 8.3, and the molar ratio of methanol to hydrogen peroxide in the feed is 21.8. The reaction pressure is 0.5 MPa, and ammonia is added at the inlet to control the feed pH at 6.5. The initial temperature is 30°C.

[0072] During the continuous reaction process, the conversion rate of hydrogen peroxide is increased by raising the reaction temperature of the first and second reactions, ensuring that the conversion rate of hydrogen peroxide is >97%.

[0073] The activity and stability of the catalyst were evaluated by different operating times, as shown in Table 6.

[0074] Table 6 Catalyst activity at different reaction times

[0075]

[0076] Comparative Example 1

[0077] 100g of TS-1 catalyst was loaded into a single reactor, using a bottom-in, top-out feeding method. The molar ratio of allyl chloride to hydrogen peroxide in the feed was 3.0, and the molar ratio of methanol to hydrogen peroxide in the feed was 6. The reaction pressure was 0.5 MPa. The initial temperature was 20℃, and the hydrogen peroxide conversion rate was maintained >97% by gradually increasing the reaction temperature.

[0078] The activity and stability of the catalyst were evaluated by different operating times, as shown in Table 7.

[0079] Table 7 Catalyst activity at different reaction times

[0080]

[0081] Comparative Example 2

[0082] 100g of TS-1 catalyst was loaded, divided into two sections of 50g each. The reactor operated with a bottom-in, top-out feed configuration. The molar ratio of allyl chloride to hydrogen peroxide was 3.0, and the molar ratio of methanol to hydrogen peroxide was 6. The reaction pressure was 0.5 MPa. Ethylene sulfonic acid was added at the inlet at a rate of 50 ppm, based on the total mass of the feed. The initial temperature was 20°C.

[0083] The secondary reaction operates using a top-in, bottom-out feeding method. The molar ratio of allyl chloride to hydrogen peroxide in the feed is 5.0, and the molar ratio of methanol to hydrogen peroxide in the feed is 20.0. The reaction pressure is 0.5 MPa, and the initial temperature is 30°C.

[0084] During the continuous reaction process, the conversion rate of hydrogen peroxide is increased by raising the reaction temperature of the first and second reactions, ensuring that the conversion rate of hydrogen peroxide is >97%.

[0085] The activity and stability of the catalyst were evaluated by different operating times, as shown in Table 8.

[0086] Table 8 Catalyst activity at different reaction times

[0087]

[0088] Comparative Example 3

[0089] 100g of TS-1 catalyst was loaded, divided into two sections of 50g each. The reactor operated with a bottom-in, top-out feed configuration. The molar ratio of allyl chloride to hydrogen peroxide was 3.0, and the molar ratio of methanol to hydrogen peroxide was 6. The reaction pressure was 0.5 MPa. The initial temperature was 20℃.

[0090] The secondary reactor operates using a top-in, bottom-out feeding method. The molar ratio of allyl chloride to hydrogen peroxide in the feed is 4.3, and the molar ratio of methanol to hydrogen peroxide in the feed is 16.7. The reaction pressure is 0.5 MPa, and N-methylaniline is added at the inlet. The feed pH is controlled at 7.0. The initial temperature is 30°C.

[0091] During the continuous reaction process, the conversion rate of hydrogen peroxide is increased by raising the reaction temperature of the first and second reactions, ensuring that the conversion rate of hydrogen peroxide is >97%.

[0092] The activity and stability of the catalyst were evaluated by different operating times, as shown in Table 9.

[0093] Table 9 Catalyst activity at different reaction times

[0094]

[0095] Although the present invention has been described in detail through the preferred embodiments described above, it should be understood that the above description should not be considered as a limitation of the present invention. Those skilled in the art will understand that modifications or adjustments can be made to the present invention based on the teachings of this specification. These modifications or adjustments should also be within the scope defined by the claims of the present invention.

Claims

1. A process for the preparation of epichlorohydrin comprising the steps of: The reaction process is carried out by using two-stage fixed bed series connection, the first reactor is lower inlet and upper outlet, and the second reactor is upper inlet and lower outlet; chloropropylene, hydrogen peroxide and organic acid enter the first reactor, the first reactor effluent and alkaline substance enter the second reactor; the organic acid is selected from one of benzene sulfonic acid, methane sulfonic acid, ethane sulfonic acid, o-toluene sulfonic acid and p-toluene sulfonic acid; the alkaline substance is selected from one or more of ammonia, trimethylamine, N-methylaniline, N-ethylaniline and 2,6-diethylaniline; the two-stage fixed bed reactor is filled with catalyst, and the catalyst is TS-1 molecular sieve.

2. The method of claim 1, wherein, The addition amount of the organic acid is 10-150 ppm, based on the feed amount of the first reactor.

3. The method of claim 1, wherein, The reaction temperature of the first reactor is 20-60 ℃, and the pressure is 0-1 Mpa.

4. The method of claim 1, wherein, The molar ratio of chloropropylene to hydrogen peroxide in the first reactor feed is 1.5-5:

1.

5. The method of claim 1, wherein, The pH of the second reactor feed is controlled to 6-7.5 by adding alkaline substance.

6. The method of claim 1, wherein, The reaction temperature of the second reactor is 30-70 ℃, and the pressure is 0-1 Mpa.

7. The method of claim 1, wherein, The molar ratio of chloropropylene to hydrogen peroxide in the second reactor feed is 2.5-10:

1.

8. The method of claim 1, wherein, Methanol is used as the solvent for the first reactor feed, and the molar ratio of methanol to hydrogen peroxide is 4-8:1; methanol is used as the solvent for the second reactor, and additional solvent is added to the second reactor, and the molar ratio of methanol to hydrogen peroxide is 12-30:1.

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