A regeneration process of catalyst for epoxidation of epichlorohydrin by hydrogen peroxide

Abstract

The present application relates to a kind of catalysts for regenerating hydrogen peroxide method epoxy chloropropane epoxidation process, comprising the following steps: 1) by inert gas, reactor is raised to a certain pressure, liquid methanol solvent is passed into reactor, the temperature of reactor is gradually increased to 120-180 DEG C, preliminary high temperature elution is carried out to catalyst;2) when the nitrogen content of the inlet and outlet of reactor is consistent, aluminum-containing substance is added in methanol, and the catalyst is continuously heat treated;3) at the same temperature, the aluminum-containing substance is switched to chlorine-containing solvent to continue cleaning the catalyst;4) after switching the chlorine-containing solvent to methanol, the washing temperature is reduced to the required reaction temperature, and the epoxidation reaction is operated.The regeneration process of the present application can effectively remove the phosphorus-containing substances and oligomers deposited on the surface of the catalyst, and the catalyst activity can be restored to the level of fresh catalyst, and the service life of the catalyst is better than that of the catalyst regenerated by calcination.

Description

Technical Field

[0001] This invention belongs to the field of epichlorohydrin production technology, specifically relating to a regeneration process for a catalyst used in the hydrogen peroxide-based epichlorohydrin epoxidation process. 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 CN 201910621470.2 describes an olefin epoxidation method. In a reactor with a height-to-diameter ratio of 100-1000, a liquid mixture of raw materials hydrogen peroxide, olefins, methanol, and alkaline additives is contacted with a titanium-silicon molecular sieve catalyst to undergo an epoxidation reaction. The reaction temperature is increased from 20-50℃ to 55-85℃, and the heating rate of the liquid heat transfer medium is 0.001-0.2℃ / hour. After running for 1640 hours, the conversion rate and selectivity decreased from 99.8% and 97.5% to 99.5% and 95.5%, respectively, and the catalyst activity still showed a significant decrease.

[0006] Because epichlorohydrin has poor stability in the presence of allyl chloride and methanol, it is prone to etherification reaction to form oligomers. As the operating time increases, the reaction temperature needs to be continuously increased to ensure the hydrogen peroxide conversion rate. Furthermore, the continuous formation of oligomers blocks the catalyst pores, causing a significant decrease in catalyst activity. Further increasing the reaction temperature will significantly increase the etherification byproducts and reduce the yield of epichlorohydrin.

[0007] Typically, when faced with the problem of decreased or deactivated catalyst activity, the catalyst needs to be removed from the reactor for regeneration, such as calcination. However, the process of disassembling and reassembling the catalyst is cumbersome and can easily cause catalyst breakage, with the breakage rate often exceeding 10% of the total catalyst volume.

[0008] Therefore, developing a simple and efficient catalyst regeneration method is particularly important for extending catalyst lifespan. Summary of the Invention

[0009] To address the issue of catalyst deactivation in existing technologies, a simple and efficient catalyst regeneration process has been developed, restoring the catalyst activity to almost the same level as fresh catalysts. This catalyst regeneration method effectively removes oligomers and phosphorus-containing substances deposited on the catalyst surface during long-term operation. Through this regeneration method, the catalyst activity can be restored to a level comparable to that of calcined regenerated catalysts. Furthermore, due to the effective removal of phosphorus-containing substances, the catalyst's service life is superior to that of calcined regenerated catalysts.

[0010] To achieve the above-mentioned objectives, the technical solution of the present invention is as follows:

[0011] A catalyst regeneration process for epichlorohydrin epoxidation using hydrogen peroxide includes the following steps:

[0012] 1) After the epichlorohydrin epoxidation reaction by hydrogen peroxide method is completed, the reactor is raised to a certain pressure by inert gas, methanol is introduced into the reactor, the reactor temperature is raised to a certain temperature, and the catalyst is initially eluted at high temperature.

[0013] 2) When the nitrogen content at the inlet and outlet of the reactor remains constant, add aluminum-containing substances to the methanol and continue to heat-treat the catalyst.

[0014] 3) At the same temperature, switch methanol to a chlorine-containing solvent to continue cleaning the catalyst;

[0015] 4) After cleaning, switch the chlorine-containing solvent to methanol and lower the washing temperature to the reaction temperature required for the epichlorohydrin epoxidation by hydrogen peroxide method, and start the epoxidation reaction feed.

[0016] In one specific implementation, the pressure in step 1) is 1.3-2.0 MPa, the temperature is 130-180°C, and the initial high-temperature elution time is 16-72 h; preferably, the pressure is 1.4-1.8 MPa, the temperature is 140-170°C, and the initial high-temperature elution time is 30-60 h.

[0017] In one specific implementation, the inert gas in step 1) is selected from any one of nitrogen, argon, helium and carbon dioxide, preferably nitrogen.

[0018] In one specific implementation, the aluminum-containing substance in step 2) is selected from one or more of aluminum isopropoxide, aluminum sec-butoxide, aluminum nitrate, and aluminum sulfate.

[0019] In one specific implementation, the amount of aluminum-containing material used in step 2) is 0.5-5 wt% of the mass of methanol, with the remainder being methanol, and the total feed amount is the same as in step 1).

[0020] In one specific implementation, in step 2), the water content in the solution containing aluminum added to methanol is <1 ppm, the pressure is 1.3-2.0 MPa, the reaction temperature is 130-180℃, and the heat treatment time is 8-24 h.

[0021] In one specific implementation scheme, the chlorine-containing substance in step 3) is selected from at least one of chloromethane, dichloroethane, trichloroethane, trichloropropane, tetrachloropropane, and pentachloropropane.

[0022] In one specific implementation, the amount of chlorine-containing substance used in step 3) is 2-10 wt% of the mass of methanol in step 1), with the remainder being methanol, and the total feed amount is the same as in step 1).

[0023] In one specific implementation, step 3) involves a pressure of 1.3-2.0 MPa, a reaction temperature of 130-180°C, and a cleaning time of 8-24 hours. In actual processes, this step can also be achieved by liquid chromatography to detect that the methanol polymer content at the reactor outlet is <0.1 wt%, then switching to methanol, continuing to introduce methanol to lower the reaction temperature to the desired temperature, and lowering the pressure to the desired pressure before feeding the reaction material. Typically, by controlling the cleaning time to 8-24 hours, the detected methanol polymer content at the reactor outlet is generally less than 0.1 wt%.

[0024] In one specific implementation, the amount of methanol introduced in step 4) is the same as in step 1), the remainder is methanol, and the total feed amount is consistent with that in step 1).

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1) The addition of aluminum-containing substances in the regeneration process of the present invention can effectively react with the phosphorus-containing substances of hydrogen peroxide stabilizer deposited on the catalyst surface, allowing the phosphorus-containing substances to enter the washing liquid from the catalyst surface, thereby eliminating the influence of phosphorus residue on catalyst activity.

[0027] 2) In the regeneration process of the present invention, the addition of chlorine-containing substances to the washing liquid can dissolve the chloropropylene polymer and epichlorohydrin etherified oligomer deposited on the catalyst surface and pores during the reaction process, eliminate the influence of heavy component deposition on the catalyst, and restore the catalyst activity to the level of a fresh catalyst.

[0028] 3) The catalyst regeneration process of this invention can achieve catalyst regeneration within the existing epoxidation reactor without disassembling the catalyst. Using the method described in this invention, the catalyst activity can be restored to the level of a fresh catalyst, achieving the same regeneration effect as external roasting, greatly saving catalyst regeneration time. Simultaneously, the catalyst regeneration method of this invention reduces losses during catalyst disassembly. Therefore, the regeneration process of this invention has high efficiency and significantly improves economic efficiency. Detailed Implementation

[0029] 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.

[0030] 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℃.

[0031] The methanol is produced by the company's methanol plant, and the product purity is >99.5%.

[0032] Aluminum isopropoxide was supplied by Aladdin Reagent Co., Ltd., and the product purity is >98%.

[0033] Aluminum sec-butoxide was supplied by Aladdin Reagent Co., Ltd., with a purity of 97%.

[0034] The dichloroethane was supplied by Beijing Inokai Technology Co., Ltd., and the product purity is >99.9%.

[0035] The trichloroethane was supplied by Beijing Inokai Technology Co., Ltd., and the product purity was 99%.

[0036] Example 1

[0037] After loading 20g of catalyst and running for 3000h until the catalyst was fully utilized, the feed of allyl chloride and hydrogen peroxide was cut off. The methanol feed rate was maintained at 0.5g / min, and the temperature was gradually increased to 130℃ at a rate of 3℃ / min. Nitrogen gas was then introduced into the reaction system to pressurize the entire system to 1.3 MPa. Timing was then started, and the catalyst was washed with methanol at the same flow rate for 72h. Once the nitrogen content in the methanol at the reactor inlet and outlet was found to be consistent, the methanol was switched to aluminum-containing methanol.

[0038] The mass ratio of aluminum isopropoxide to methanol in aluminum-containing methanol was 0.5:100. The water content in the aluminum-containing methanol solution was measured to be 0.2 ppm. The washing process was continued at 130℃, 1.3 MPa, and a flow rate of 0.5 g / min for 24 h. After the P content in the methanol at the inlet and outlet of the reactor was found to be consistent, the methanol was switched to chlorinated methanol.

[0039] The mass ratio of dichloroethane to methanol in chlorinated methanol is 2:100. The reactor is washed at 130℃, 1.3 MPa, and a flow rate of 0.5 g / min for 24 h. After the polymer content of methanol at the reactor outlet is detected by liquid chromatography as <0.1 wt%, methanol is switched to methanol. Methanol is then introduced to reduce the reaction temperature to the required reaction temperature and the pressure is reduced to the required pressure before the reaction is started.

[0040] The epoxidation reaction conditions are as follows:

[0041] The reaction started at 20°C and 0.3 MPa, with a methanol to hydrogen peroxide molar ratio of 2.5:1 and a chloropropene to hydrogen peroxide molar ratio of 8:1.

[0042] The activity of the regenerated catalyst was evaluated by hydrogen peroxide conversion and epichlorohydrin selectivity under different operating times and reaction temperatures, as shown in Table 1.

[0043] Table 1 Catalyst activity after regeneration

[0044]

[0045] Example 2

[0046] After loading 20g of catalyst and running for 3000h until the catalyst was fully utilized, the feed of allyl chloride and hydrogen peroxide was cut off. The methanol feed rate was maintained at 0.5g / min, and the temperature was gradually increased to 145℃ at a rate of 4℃ / min. Nitrogen gas was then introduced into the reaction system to pressurize the entire system to 1.5 MPa. Timing was then started, and the catalyst was washed with methanol at the same flow rate for 60h. Once the nitrogen content in the methanol at the reactor inlet and outlet was consistent, the methanol was switched to aluminum-containing methanol.

[0047] The mass ratio of aluminum isopropoxide to methanol in aluminum-containing methanol was 1.5:100. The water content in the aluminum-containing methanol solution was measured to be 0.3 ppm. The washing process was continued at 145℃, 1.5 MPa, and a flow rate of 0.5 g / min for 16 h. After the P content in the methanol at the inlet and outlet of the reactor was found to be consistent, the methanol was switched to chlorinated methanol.

[0048] The mass ratio of trichloroethane to methanol in chlorinated methanol is 4:100. The reactor is washed at 145℃, 1.5 MPa, and a flow rate of 0.5 g / min for 16 h. After the polymer content of methanol at the reactor outlet is detected by liquid chromatography as <0.1 wt%, methanol is switched to methanol. Methanol is then introduced to reduce the reaction temperature to the required reaction temperature and the pressure is reduced to the required pressure before the reactor is fed into the reaction.

[0049] The regenerated catalyst activity was evaluated according to the method described in Example 1, and the results are shown in Table 2.

[0050] Table 2 Catalyst activity after regeneration

[0051]

[0052] Example 3

[0053] After loading 20g of catalyst and running for 3000h until the catalyst was fully utilized, the feed of allyl chloride and hydrogen peroxide was cut off. The methanol feed rate was maintained at 0.5g / min, and the temperature was gradually increased to 160℃ at a rate of 4℃ / min. Nitrogen gas was then introduced into the reaction system to pressurize the entire system to 1.8 MPa. Timing was then started, and the catalyst was washed with methanol at the same flow rate for 48h. Once the nitrogen content in the methanol at the reactor inlet and outlet was consistent, the methanol was switched to aluminum-containing methanol.

[0054] The mass ratio of aluminum sec-butoxide to methanol in aluminum-containing methanol was 3.5:100. The water content in the aluminum-containing methanol solution was detected to be 0.6 ppm. The washing was continued at 160℃, 1.8 MPa, and a flow rate of 0.5 g / min for 12 h. After the P content in the methanol at the inlet and outlet of the reactor was found to be consistent, the methanol was switched to chlorinated methanol.

[0055] The mass ratio of dichloroethane to methanol in chlorinated methanol is 7:100. The reactor is washed at 160℃, 1.8 MPa, and a flow rate of 0.5 g / min for 12 h. After the polymer content of methanol at the reactor outlet is detected by liquid chromatography as <0.1 wt%, methanol is switched to methanol. Methanol is then introduced to reduce the reaction temperature to the required reaction temperature and the pressure is reduced to the required pressure before the reaction is started.

[0056] The regenerated catalyst activity was evaluated according to the method described in Example 1, and the results are shown in Table 3.

[0057] Table 3 Catalyst activity after regeneration

[0058]

[0059] Example 4

[0060] After loading 20g of catalyst and running for 3000h until the catalyst was fully utilized, the feed of allyl chloride and hydrogen peroxide was cut off. The methanol feed rate was maintained at 0.5g / min, and the temperature was gradually increased to 180℃ at a rate of 5℃ / min. Nitrogen gas was then introduced into the reaction system to pressurize the entire system to 2.0 MPa. Timing was then started, and the catalyst was washed with methanol at the same flow rate for 16h. Once the nitrogen content in the methanol at the reactor inlet and outlet was confirmed to be consistent, the methanol was switched to aluminum-containing methanol.

[0061] The mass ratio of aluminum sec-butoxide to methanol in aluminum-containing methanol was 5.0:100. The water content in the aluminum-containing methanol solution was measured to be 0.9 ppm. The washing process was continued at 180℃, 2.0 MPa, and a flow rate of 0.5 g / min for 8 hours. After the P content in the methanol at the inlet and outlet of the reactor was found to be consistent, the methanol was switched to chlorinated methanol.

[0062] The mass ratio of pentachloropropane to methanol in chlorinated methanol is 10:100. The washing process is maintained at 180℃, 2.0 MPa, and a flow rate of 0.5 g / min for 8 hours. After the polymer content of methanol at the reactor outlet is detected by liquid chromatography as <0.1 wt%, methanol is switched to methanol. Methanol is then introduced to reduce the reaction temperature to the required reaction temperature and the pressure is reduced to the required pressure before the feed reaction.

[0063] The regenerated catalyst activity was evaluated according to the method described in Example 1, and the results are shown in Table 4.

[0064] Table 4 Catalyst activity after regeneration

[0065]

[0066] Comparative Example 1

[0067] After loading 20g of catalyst and running for 3000h until the catalyst was fully utilized, the feed of allyl chloride and hydrogen peroxide was cut off. The methanol feed rate was maintained at 0.5g / min, and the temperature was gradually increased to 180℃ at a rate of 5℃ / min. Nitrogen gas was then introduced into the reaction system to pressurize the entire system to 2.0 MPa. Timing was then started, and the catalyst was washed with methanol at the same flow rate for 16h. Once the nitrogen content in the methanol at the reactor inlet and outlet was confirmed to be consistent, the reaction temperature and pressure were reduced to the required levels before the reaction was resumed.

[0068] The regenerated catalyst activity was evaluated according to the method described in Example 1, and the results are shown in Table 5.

[0069] Table 5 Catalyst activity after regeneration

[0070]

[0071] Comparative Example 2

[0072] After loading 20g of catalyst and running for 3000h, the catalyst was removed, dried at 120℃ for 12h, and then placed in a muffle furnace for calcination. The calcination conditions were 450℃ for 4h and a heating rate of 2℃ / h.

[0073] The catalyst was regenerated and then loaded into the reactor. The regenerated catalyst activity was evaluated according to the method described in Example 1. The results are shown in Table 6.

[0074] Table 6 Catalyst activity after regeneration

[0075]

[0076]

[0077] It is evident that, through the regeneration process of this invention, the catalyst activity can be restored to a fresh level, comparable to that of a calcined regenerated catalyst. Due to the effective removal of phosphorus-containing substances, the catalyst's service life is superior to that of a calcined regenerated catalyst.

[0078] 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 catalyst regeneration process for epichlorohydrin epoxidation using hydrogen peroxide, characterized in that, Includes the following steps: Step 1) After the epichlorohydrin epoxidation reaction by hydrogen peroxide is completed, the reactor is raised to a certain pressure by inert gas, methanol is introduced into the reactor, the reactor temperature is raised to a certain temperature, and the catalyst is initially eluted at high temperature. Step 2) When the nitrogen content at the inlet and outlet of the reactor remains constant, add aluminum-containing substances to the methanol and continue to heat-treat the catalyst. Step 3) At the same temperature, switch the aluminum-containing material from Step 2) to a chlorine-containing material to continue cleaning the catalyst; Step 4) After cleaning, the solvent for the chlorine-containing substances in Step 3) is switched to methanol, and the washing temperature is lowered to the reaction temperature required for the epichlorohydrin epoxidation by hydrogen peroxide method. The epoxidation reaction is then started.

2. The catalyst regeneration process according to claim 1, characterized in that, The pressure mentioned in step 1) is 1.3-2.0 MPa, the temperature is 130-180℃, and the initial high-temperature elution time is 16-72 h.

3. The catalyst regeneration process according to claim 2, characterized in that, The pressure mentioned in step 1) is 1.4-1.8 MPa, the temperature is 140-170℃, and the initial high-temperature elution time is 30-60 h.

4. The catalyst regeneration process according to claim 1, characterized in that, In step 1), the inert gas is selected from any one of nitrogen, argon, and helium.

5. The catalyst regeneration process according to claim 4, characterized in that, In step 1), the inert gas is nitrogen.

6. The catalyst regeneration process according to claim 1, characterized in that, In step 2), the aluminum-containing substance is selected from one or more of aluminum isopropoxide, aluminum sec-butoxide, aluminum nitrate, and aluminum sulfate.

7. The catalyst regeneration process according to claim 1, characterized in that, The amount of aluminum-containing material used in step 2) is 0.5-5 wt% of the mass of methanol, with the remainder being methanol, and the total feed amount is the same as in step 1).

8. The catalyst regeneration process according to claim 1, characterized in that, Step 2) Add the aluminum-containing substance to the methanol solution with a water content of <1ppm, pressure of 1.3-2.0Mpa, reaction temperature of 130-180℃, and heat treatment time of 8-24h.

9. The catalyst regeneration process according to claim 1, characterized in that, The chlorine-containing substance mentioned in step 3) is selected from at least one of chloromethane, dichloroethane, trichloroethane, trichloropropane, tetrachloropropane, and pentachloropropane.

10. The catalyst regeneration process according to claim 1, characterized in that, In step 3), the amount of chlorine-containing substance used is 2-10 wt% of the mass of methanol, with the remainder being methanol, and the total feed amount is the same as in step 1).

11. The catalyst regeneration process according to claim 1, characterized in that, In step 3), the pressure is 1.3-2.0 MPa, the reaction temperature is 130-180℃, and the cleaning time is 8-24 hours.

12. The catalyst regeneration process according to claim 1, characterized in that, The amount of methanol introduced in step 4) is the same as in step 1).

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