A method for catalytic decomposition of hydrogen peroxide in aqueous methanol

Abstract

The present application relates to the field of hydrogen peroxide decomposition, and discloses a method for catalytically decomposing hydrogen peroxide in methanol aqueous solution. The method for catalytically decomposing hydrogen peroxide in methanol aqueous solution comprises the following steps: in the presence of a catalyst, decomposing the methanol aqueous solution containing hydrogen peroxide, and the decomposition reaction conditions include: the temperature is 30-100 DEG C; wherein, the catalyst comprises titanium silicalite with MFI topology and alumina; the content of the titanium silicalite with MFI topology is 40-90 mass% and the content of the alumina is 10-60 mass% based on the total amount of the catalyst; and the side pressure crushing strength of the catalyst is 70-150 N / cm. The method selects the catalyst containing the titanium silicalite with MFI topology and the alumina, can reduce the mass fraction of hydrogen peroxide, and avoids a large amount of loss of active components in a long-period operation process, and the decomposition activity remains stable.

Description

Technical Field

[0001] This invention relates to the technical field of hydrogen peroxide decomposition, and more specifically to a method for catalytically decomposing hydrogen peroxide in an aqueous methanol solution. Background Technology

[0002] Epichlorohydrin is an important basic organic chemical raw material and intermediate, widely used in the synthesis of various industrial products such as epoxy resins, chlorohydrin rubber, pharmaceuticals, pesticides, surfactants, and plasticizers.

[0003] Patent application CN101747297A discloses a method for the continuous and stable synthesis of epichlorohydrin over a long period of time via an epoxidation reaction of 3-chloropropene with hydrogen peroxide in the presence of a titanium silicate molecular sieve catalyst and methanol solvent, achieving a hydrogen peroxide conversion rate higher than 97% and an epichlorohydrin selectivity higher than 95%. However, during long-term operation, the hydrogen peroxide conversion rate typically remains between 97% and 99%, resulting in the epoxidation reaction product containing 0.05% to 0.5% by mass of hydrogen peroxide.

[0004] Patent application CN106140186A discloses a hydrogen peroxide decomposition catalyst and a method for decomposing hydrogen peroxide in the products of a hydrogen peroxide epoxidation reaction of 3-chloropropene and hydrogen peroxide. The catalyst contains 1%-20% by mass of Group IVB metal oxides, 1%-20% by mass of Group VIB metal oxides, 1%-20% by mass of Group IB metal oxides, and 40%-97% by mass of Group IIIA metal oxides. The decomposition of hydrogen peroxide in the epoxidation reaction products is carried out at a temperature of 0-50℃ and a pressure of 0.1-2.0 MPa, reducing the hydrogen peroxide content in the epoxidation reaction products to below 0.02% by mass. However, this patent does not disclose the lateral pressure breakage strength of the catalyst. Studies have found that catalysts prepared using the method disclosed in patent application CN106140186A have lateral pressure breakage strengths below 70 N / cm, making them prone to breakage and failing to meet the strength requirements of industrial fixed-bed reactors for catalyst loading.

[0005] Patent application CN114471591A discloses a hydrogen peroxide decomposition catalyst and its application in the catalytic decomposition of hydrogen peroxide in methanol-water solutions. The hydrogen peroxide decomposition catalyst contains a certain amount of Group IVB, Group VIB, Group IB, and Group IIIA metal oxides. The catalyst exhibits a side-compression crushing strength exceeding 70 N / cm and can reduce the mass fraction of hydrogen peroxide in methanol-water solutions to below 0.02%. However, this patent does not disclose the changes in catalyst component content during long-term operation. Research has found that catalysts prepared using the method disclosed in patent application CN114471591A are prone to loss of Group VIB metal elements (such as chromium, molybdenum, and tungsten) and Group IB metal elements (such as copper) during long-term use, making it difficult to meet the catalyst lifetime requirements of industrial fixed-bed reactors. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of existing technologies in the decomposition of hydrogen peroxide, which cannot simultaneously retain the active components of the catalyst and have a low mass fraction of hydrogen peroxide after decomposition. This invention provides a method for catalytically decomposing hydrogen peroxide in methanol aqueous solution. This method uses a catalyst containing titanium silicate molecular sieves with MFI topology and alumina, which can reduce the mass fraction of hydrogen peroxide in the reaction feedstock. At the same time, it avoids a large loss of components during long-term operation and maintains stable decomposition activity.

[0007] To achieve the above objectives, the present invention provides a method for the catalytic decomposition of hydrogen peroxide in an aqueous methanol solution, wherein the method comprises:

[0008] In the presence of a catalyst, an aqueous methanol solution containing hydrogen peroxide is subjected to a decomposition reaction, wherein the conditions for the decomposition reaction include a temperature of 30-100°C.

[0009] The catalyst comprises a titanium-silicon molecular sieve with an MFI topology and alumina; based on the total amount of catalyst, the content of the titanium-silicon molecular sieve with the MFI topology is 40-90% by mass, and the content of the alumina is 10-60% by mass; the lateral crushing strength of the catalyst is 70-150 N / cm.

[0010] The method provided by this invention uses a catalyst containing titanium-silicon molecular sieves with MFI topology and alumina to decompose hydrogen peroxide. This not only reduces the mass fraction of hydrogen peroxide in methanol aqueous solution containing hydrogen peroxide to below 0.02%, improving the decomposition efficiency of hydrogen peroxide, but also shows no significant loss of components in the catalyst and maintains stable decomposition activity during long-term (preferably more than 200 hours) operation.

[0011] The method provided by this invention can decompose methanol aqueous solution containing hydrogen peroxide before discharge, effectively eliminating the potential environmental hazards of high hydrogen peroxide wastewater, and is both environmentally friendly and safe. Detailed Implementation

[0012] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0013] This invention provides a method for the catalytic decomposition of hydrogen peroxide in an aqueous methanol solution, wherein the method includes:

[0014] In the presence of a catalyst, an aqueous methanol solution containing hydrogen peroxide is subjected to a decomposition reaction, wherein the conditions for the decomposition reaction include a temperature of 30-100°C.

[0015] The catalyst comprises a titanium-silicon molecular sieve with an MFI topology and alumina; based on the total amount of catalyst, the content of the titanium-silicon molecular sieve with the MFI topology is 40-90% by mass, and the content of the alumina is 10-60% by mass; the lateral crushing strength of the catalyst is 70-150 N / cm.

[0016] Existing titanium-silicon molecular sieves with MFI topology are typically used in epoxidation reactions. This is primarily because the main active sites of these sieves are isolated four-coordinate framework titanium. Hydrogen peroxide interacts with this isolated framework titanium to form a Ti-OOH intermediate, which then undergoes an epoxidation reaction with the olefin to generate the relevant epoxidation products. However, there are currently no reports on the direct use of titanium-silicon molecular sieves for hydrogen peroxide decomposition. The method provided in this invention uses a catalyst containing titanium-silicon molecular sieves with MFI topology and alumina. When used to decompose hydrogen peroxide, this method not only improves the decomposition efficiency, reducing the mass fraction of hydrogen peroxide in methanol-water solutions to below 0.02%, but also shows no significant loss of components during long-term operation (preferably more than 200 hours), maintaining stable decomposition activity.

[0017] The method provided by this invention can decompose methanol aqueous solution containing hydrogen peroxide before discharge, effectively eliminating the potential environmental hazards of high hydrogen peroxide wastewater, and is both environmentally friendly and safe.

[0018] In this invention, the lateral crushing strength of the catalyst was measured using a ZQJ-II intelligent particle strength tester manufactured by Dalian Intelligent Testing Machine Factory, with reference to the HG / T2782-1996 standard. The measured lateral crushing strength was the average value of 20 particles.

[0019] In this invention, the content of each component in the catalyst is determined by inductively coupled plasma (ICP).

[0020] In this invention, preferably, based on the total amount of catalyst, the content of the titanium-silicon molecular sieve with the MFI topology is 50-85% by mass, and the content of alumina is 15-50% by mass. The advantage of this preferred embodiment is that the content of titanium-silicon molecular sieve in the catalyst is further increased, thereby improving the hydrogen peroxide decomposition efficiency.

[0021] In this invention, preferably, the lateral crushing strength of the catalyst is 75-120 N / cm. The advantage of this preferred embodiment is that the catalyst has high strength, which facilitates catalyst loading in industrial plants and allows for long-term use.

[0022] In this invention, the source of alumina is not particularly limited, as long as alumina can be provided. Preferably, the alumina is provided by aluminum hydroxide powder and / or aluminum sol.

[0023] In this invention, preferably, the titanium-silicon molar ratio of the titanium-silicon molecular sieve with the MFI topology is 1:20-1:100. The advantage of this preferred embodiment is that the titanium-silicon molecular sieve has a high titanium species content, thereby improving the efficiency of the catalyst in decomposing hydrogen peroxide.

[0024] In this invention, there is no particular limitation on the shape of the catalyst, and any shape conventionally defined in the art can be adapted to this invention.

[0025] In this invention, the preparation method of the catalyst is not particularly limited, and it can be prepared by methods conventionally defined in the art, such as the preparation method of titanium-silicon molecular sieve catalyst disclosed in CN102259023A. It will not be described in detail in this invention.

[0026] In this invention, the method is applicable to the decomposition of hydrogen peroxide in any methanol-water solution containing hydrogen peroxide, and the content of hydrogen peroxide is not particularly limited. Preferably, based on the total amount of the methanol-water solution containing hydrogen peroxide, the content of hydrogen peroxide in the methanol-water solution containing hydrogen peroxide is 0.02-1% by mass, more preferably 0.05-0.6% by mass.

[0027] In this invention, the method is applicable to the decomposition of hydrogen peroxide in any methanol-water solution containing hydrogen peroxide, and the content of methanol is not particularly limited. Preferably, based on the total amount of the methanol-water solution containing hydrogen peroxide, the methanol content in the methanol-water solution containing hydrogen peroxide is 5-95% by mass, more preferably 20-80% by mass.

[0028] In this invention, preferably, the methanol-water solution containing hydrogen peroxide may also contain other water-soluble impurities. The type of water-soluble impurities is not specifically limited in this invention; for example, they may be 1-chloro-3-methoxy-2-propanol, 3-chloro-1,2-propanediol, etc. The content of water-soluble impurities is not particularly limited in this invention. Preferably, based on the total amount of the methanol-water solution containing hydrogen peroxide, the total content of the water-soluble impurities is less than 1% by mass.

[0029] In this invention, the source of the methanol-water solution containing hydrogen peroxide is not particularly limited. Preferably, the methanol-water solution containing hydrogen peroxide is provided by at least one of the following: epoxidation reaction of 3-chloropropene with hydrogen peroxide, epoxidation reaction of propylene with hydrogen peroxide, and hydrogen peroxide production reaction by anthraquinone process; more preferably, it is provided by epoxidation reaction of 3-chloropropene with hydrogen peroxide.

[0030] In this invention, the temperature range for the decomposition reaction is relatively wide. Preferably, the conditions for the decomposition reaction include a temperature of 40-90℃, for example, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90℃, or any value between two groups, and more preferably 50-80℃. Using the catalyst provided by this invention to catalyze the decomposition of methanol-water solutions containing hydrogen peroxide allows for milder reaction conditions and improves industrial production value.

[0031] In this invention, the pressure range for the decomposition reaction is relatively wide. Preferably, the conditions for the decomposition reaction include a pressure of 0.1-1 MPa, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 MPa, and any value between two groups, and more preferably 0.1-0.5 MPa. Using the catalyst provided by this invention to catalytically decompose methanol-water solutions containing hydrogen peroxide allows for milder reaction conditions and improves industrial value.

[0032] In this invention, the distribution form of the catalyst is not particularly limited. For example, it can be dispersed in the reactor as particles, moving with the methanol-water solution containing hydrogen peroxide, or it can be distributed in the reactor as a bed. According to a preferred embodiment of the invention, the decomposition reaction is carried out in a reaction vessel. According to another preferred embodiment of the invention, the decomposition reaction is carried out in a fixed-bed reactor. Preferably, the decomposition reaction is carried out in a fixed-bed reactor. The advantage of carrying the decomposition reaction in the above-mentioned reactors is that it facilitates the loading of catalysts for industrial plants and long-term operation.

[0033] In this invention, the decomposition reaction takes place in the reactor when the catalyst is dispersed in particulate form and moves with the methanol-water solution containing hydrogen peroxide. Preferably, the amount of catalyst used is 0.1-5% of the mass of the methanol-water solution containing hydrogen peroxide, more preferably 0.1-1%. Preferably, the residence time of the methanol-water solution containing hydrogen peroxide in the reactor is 0.01-24 h, more preferably 0.1-10 h.

[0034] In this invention, when the catalyst is distributed in the reactor in the form of a bed, the decomposition reaction is carried out in a fixed-bed reactor. Preferably, the feed liquid hourly space velocity (LHSV) of the methanol-water solution containing hydrogen peroxide is 0.01-20 h⁻¹. -1 Further preferably 0.1-10h -1 .

[0035] In a preferred embodiment of this invention, the method further includes mixing the products generated by the decomposition reaction with an optional inert gas and then feeding them together into a gas-liquid separator to remove non-condensable gases. This operation is a conventionally defined impurity removal method in the art, and this invention does not specifically limit it; those skilled in the art can adjust it according to actual needs.

[0036] According to a preferred embodiment of the present invention, the method includes the following steps: in the presence of a catalyst, a methanol aqueous solution containing hydrogen peroxide is subjected to a decomposition reaction, wherein the conditions of the decomposition reaction include: a temperature of 30-100°C and a pressure of 0.1-1 MPa; then the products generated by the decomposition reaction are mixed with an optional inert gas and fed together into a gas-liquid separator to remove non-condensable gases therein.

[0037] The methanol-water solution containing hydrogen peroxide is an epoxidation product obtained by epoxidation of 3-chloropropene and hydrogen peroxide. The epoxidation reaction is carried out in the presence of the catalyst described in this invention. Based on the total amount of the methanol-water solution containing hydrogen peroxide, the hydrogen peroxide content in the methanol-water solution containing hydrogen peroxide is 0.02-1% by mass, and the methanol content is 5-95% by mass. The epoxidation reaction also includes separation, extraction, etc., to obtain the methanol-water solution containing hydrogen peroxide. This invention does not particularly limit the specific operation method and conditions.

[0038] The catalysts used for the decomposition and epoxidation reactions include titanium-silicon molecular sieves with MFI topology and alumina. The titanium-silicon molar ratio of the titanium-silicon molecular sieve with MFI topology is 1:20-1:100. Based on the total amount of catalyst, the content of the titanium-silicon molecular sieve with MFI topology is 40-90% by mass, and the content of alumina is 10-60% by mass. The lateral crushing strength of the catalyst is 70-150 N / cm.

[0039] The method of this invention can decompose most of the residual hydrogen peroxide in methanol aqueous solution before discharge, effectively eliminating the potential environmental hazards of high hydrogen peroxide wastewater, improving the environmental protection and safety of the epichlorohydrin production process by the epoxidation reaction of 3-chloropropene and hydrogen peroxide, and preventing the large loss of components during long-term operation of the catalyst, maintaining stable decomposition activity. Compared with the prior art, it can better meet the industrial requirements for catalyst life.

[0040] The present invention will be described in detail below through embodiments.

[0041] In this invention, the titanium-silicon molecular sieve used in the examples and comparative examples was produced by Hunan Jianchang Petrochemical Co., Ltd., with the brand name HTS; starch and citric acid were both analytical grade reagents, and water was deionized water.

[0042] To illustrate the technical solution of the present invention, a simulation experiment was conducted. In the examples and comparative examples, hydrogen peroxide was an analytical grade reagent with a mass content of 30%; methanol was an analytical grade reagent with a mass content greater than 99.5%.

[0043] In this invention, in the embodiments, the lateral crushing strength of the catalyst was measured using a ZQJ-II intelligent particle strength tester manufactured by Dalian Intelligent Testing Machine Factory, with reference to the HG / T2782-1996 standard. The measured lateral crushing strength was the average value of 20 particles.

[0044] In this invention, the hydrogen peroxide content in the reactor feed and discharge is determined by indirect iodometric titration.

[0045] Preparation Examples 1-3 and Comparative Preparation Example 1 are used to illustrate the preparation of the catalyst.

[0046] Preparation Example 1

[0047] 175.00 g of HTS raw powder (titanium-silicon molar ratio of 1:30) and 152.13 g of aluminum hydroxide powder (produced by Shandong Zibo Taiguang Chemical Co., Ltd., with an alumina content of 71.9% and a BET specific surface area of ​​358 m²) were mixed. 2 70.00 g of starch and 12.10 g of guar gum powder (produced by Lankao Plant Gum Factory, Henan Province) were mixed in a kneader for 20 min; then 292.88 g of aluminum sol with an alumina content of 22.4% (produced by Hunan Jianchang Petrochemical Co., Ltd.), 14.15 g of octylphenol polyoxyethylene (15) ether (OP-15, produced by Xingtai Kewang Chemical Additives Co., Ltd., Hebei Province) and 15.00 g of deionized water were added sequentially and kneaded into a dough. The total mass of starch, guar gum powder and OP-15 in the dough was 55.0% of the mass of HTS raw powder. Kneading was continued for 70 min to obtain an extrudable plastic molded body; the dough was then extruded using a twin-screw extruder. The perforated plate was extruded into wet, slender, solid cylindrical strips. After being dried at room temperature for 24 hours, the strips were placed in a box-type resistance furnace and heated from room temperature to 120°C at a heating rate of 5°C / min and held for 5 hours. Then, the temperature was increased to 550°C at a heating rate of 3°C / min and held for 15 hours. After natural cooling, cylindrical strip catalyst A1 was obtained. The mass content of the titanium silicate molecular sieve in the shaped catalyst was 50%, the alumina content was 50%, the mass ratio of alumina from aluminum hydroxide powder to alumina from aluminum sol was 1.67, and its lateral crushing strength was 95.4 N / cm.

[0048] Preparation Example 2

[0049] 210.00 g of HTS raw powder (titanium-silicon molar ratio of 1:50) and 112.90 g of aluminum hydroxide powder (produced by Shandong Zibo Taiguang Chemical Co., Ltd., with an alumina content of 71.9% and a BET specific surface area of ​​358 m²) were added. 2 113.75 g of starch and 8.75 g of guar gum powder (produced by Lankao Plant Gum Factory, Henan Province) were mixed in a kneader for 30 min; then 261.18 g of aluminum sol with an alumina content of 22.5% (produced by Hunan Jianchang Petrochemical Co., Ltd.), 17.50 g of octylphenol polyoxyethylene (15) ether (OP-15, produced by Xingtai Kewang Chemical Additives Co., Ltd., Hebei Province) and 21.00 g of deionized water were added sequentially and kneaded into a dough. The total mass of starch, guar gum powder and OP-15 in the dough was 66.7% of the mass of the HTS raw powder. Kneading was continued for 90 min to obtain an extrudable plastic molded body; the dough was then extruded using a twin-screw extruder. The perforated plate was extruded into wet, slender, solid cylindrical strips. After being dried at room temperature for 36 hours, the strips were placed in a box-type resistance furnace and heated from room temperature to 120°C at a heating rate of 3°C / min and held for 3 hours. Then, the temperature was increased to 560°C at a heating rate of 5°C / min and held for 20 hours. After natural cooling, cylindrical strip catalyst A2 was obtained. The mass content of the titanium silicate molecular sieve in the shaped catalyst was 60%, the alumina content was 40%, the mass ratio of alumina from aluminum hydroxide powder to alumina from aluminum sol was 1.38, and its lateral crushing strength was 98.8 N / cm.

[0050] Preparation Example 3

[0051] 262.50 g of HTS raw powder (titanium-silicon molar ratio of 1:70) and 68.35 g of aluminum hydroxide powder (produced by Shandong Zibo Taiguang Chemical Co., Ltd., alumina content of 74.2%, BET specific surface area of ​​445 m²) were added. 2 78.75 g of starch and 8.75 g of guar gum powder (produced by Lankao Plant Gum Factory, Henan Province) were mixed in a kneader for 60 min; then 164.39 g of aluminum sol with an alumina content of 22.4% (produced by Hunan Jianchang Petrochemical Co., Ltd.), 17.50 g of octylphenol polyoxyethylene (15) ether (OP-15, produced by Xingtai Kewang Chemical Additives Co., Ltd., Hebei Province) and 21.00 g of deionized water were added sequentially and kneaded into a dough. The total mass of starch, guar gum powder and OP-15 in the dough was 40.0% of the mass of HTS raw powder. Kneading was continued for 120 min to obtain an extrudable plastic molded body; the dough was then extruded using a twin-screw extruder. The perforated plate was extruded into wet, slender, solid cylindrical strips. After being dried at room temperature for 24 hours, the strips were placed in a box-type resistance furnace and heated from room temperature to 120°C at a heating rate of 3°C / min and held for 2 hours. Then, the temperature was increased to 270°C at a heating rate of 5°C / min and held for 1 hour. Finally, the temperature was increased to 560°C at a heating rate of 4°C / min and held for 24 hours. After natural cooling, cylindrical strip catalyst A3 was obtained. The mass content of the titanium silicate molecular sieve in the shaped catalyst was 75%, the alumina content was 25%, the mass ratio of alumina from aluminum hydroxide powder to alumina from aluminum sol was 1.38, and its lateral crushing strength was 81.2 N / cm.

[0052] Comparative Preparation Example 1

[0053] Hydrogen peroxide decomposition catalyst B1 was prepared according to the method provided in CN114471591.

[0054] 139.73 g of aluminum hydroxide powder (alumina content 71.56% by mass, produced by Shandong Zibo Taiguang Chemical Co., Ltd.), 241.97 g of titanium dioxide (chemically pure reagent), 90.00 g of starch (analytical reagent), 10.00 g of guar gum powder (produced by Henan Lankao Plant Gum Factory), 264.26 g of aluminum sol with an alumina content of 22.69% by mass (produced by Hunan Jianchang Petrochemical Co., Ltd.), 20.00 g of octylphenol polyoxyethylene (15) ether (OP-15, produced by Hebei Xingtai Kewang Chemical Additives Co., Ltd.), and 3.00 g of dilute nitric acid with a nitric acid content of 2% by mass were fully kneaded in a multifunctional catalyst molding machine (produced by South China University of Technology Science and Technology Industrial Plant) to obtain a wet plastic body, which was then extruded into strips. Solid cylindrical strips are dried at 8-16℃ for 66 hours, then placed in a drying oven at 55℃ for 8 hours. After that, they are placed in a box-type resistance furnace and heated from 8℃ to 120℃ at a heating rate of 9℃ / min and held for 3 hours. Then, they are heated to 600℃ at a heating rate of 10℃ / min and held for 30 hours. After natural cooling, a cylindrical strip composite metal oxide containing 60.01% by mass of titanium dioxide and 39.99% by mass of aluminum oxide is obtained.

[0055] The mass ratio of aluminum hydroxide powder, titanium dioxide, acidic aluminum sol, starch and guar gum powder, OP-15 and 2% nitric acid is 100:173.2:189.1:71.6:14.3:2.1.

[0056] A cylindrical bar composite metal oxide containing 60.01% by mass titanium dioxide and 39.99% by mass aluminum oxide was impregnated for 24 hours in a sealed container at 35°C with 250.00 g of an aqueous solution containing 12.42 g of ammonium molybdate tetrahydrate and 17.00 g of copper nitrate trihydrate. The impregnated material was then dried at 85°C and 105°C for 12 hours each, and then calcined at 550°C for 20 hours. After natural cooling, a cylindrical bar hydrogen peroxide decomposition catalyst B1 containing 54.32% by mass titanium dioxide, 6.11% by mass molybdenum trioxide, 3.38% by mass copper oxide, and 36.19% by mass aluminum oxide was obtained. The catalyst had a lateral crushing strength of 115.1 N / cm.

[0057] Example 1

[0058] The hydrogen peroxide decomposition catalyst A1 prepared in Preparation Example 1 was used to decompose hydrogen peroxide in a methanol-water solution in a stirred tank reactor. The catalyst was shaped into short strips 3-5 mm long. The methanol-water solution contained 48.001% by mass of methanol, 0.504% by mass of hydrogen peroxide, and the balance water. The decomposition reaction conditions were: stirring speed 600 r / min, decomposition temperature 60℃, decomposition pressure 0.4 MPa, catalyst dosage 5% of the mass of the methanol-water solution, and decomposition time 30 min. Samples of the feed and discharge liquids were taken separately, and iodine was produced by reacting hydrogen peroxide with potassium iodide in ammonium molybdate and acidic medium according to the method disclosed in CN106140186A. The iodine was then titrated with a standard solution of sodium thiosulfate to determine the mass fraction of hydrogen peroxide.

[0059] The mass fraction of hydrogen peroxide before decomposition was determined to be 0.504%, and the mass fraction of hydrogen peroxide after decomposition was 0.005%, with a decomposition rate of 99.0%.

[0060] Example 2

[0061] The hydrogen peroxide decomposition catalyst A1 prepared in Preparation Example 1 was used to decompose hydrogen peroxide in a methanol-water solution in a fixed-bed reactor. The catalyst was shaped into short strips 3-5 mm long. The methanol-water solution contained 47.281% by mass of methanol, 0.508% by mass of hydrogen peroxide, and the balance being water. The decomposition reaction conditions were: a feed space-time velocity of 1 h⁻¹ for the methanol-water solution. -1 The decomposition temperature was 60℃, the decomposition pressure was 0.1MPa, and the continuous feeding time was 24h. Liquid samples from the feed and discharge were taken separately, and the mass fraction of hydrogen peroxide was determined according to the method in Example 1.

[0062] After continuous feeding for 24 hours, the mass fraction of hydrogen peroxide before decomposition was 0.508%, and the mass fraction of hydrogen peroxide after decomposition was 0.008%, with a decomposition rate of 98.4%.

[0063] Example 3

[0064] The hydrogen peroxide decomposition catalyst A1 prepared in Preparation Example 1 was used to decompose hydrogen peroxide in a methanol-water solution in a fixed-bed reactor. The catalyst was shaped into short strips 3-5 mm in length. The methanol-water solution contained 46.244% by mass methanol, 0.645% by mass chloropropanediol monomethyl ether, 0.167% by mass 3-chloro-1,2-propanediol, and 0.512% by mass hydrogen peroxide, with the balance being water. The decomposition reaction conditions were: a feed space-time of 3 h⁻¹ for the methanol-water solution. -1The decomposition temperature was 75℃, the decomposition pressure was 0.1MPa, and the continuous feeding time was 24h. Liquid samples from the feed and discharge were taken separately, and the mass fraction of hydrogen peroxide was determined according to the method in Example 1.

[0065] After continuous feeding for 24 hours, the mass fraction of hydrogen peroxide before decomposition was 0.512%, and the mass fraction of hydrogen peroxide after decomposition was 0.003%, with a decomposition rate of 99.4%.

[0066] Example 4

[0067] The catalytic decomposition of hydrogen peroxide in methanol-water solution was carried out using the method of Example 3, except that the catalyst used was catalyst A2 prepared in Preparation Example 2, and the feed mass space-time velocity of the methanol-water solution was 6 h⁻¹. -1 The decomposition temperature is 80℃ and the decomposition pressure is 0.3MPa.

[0068] After continuous feeding for 24 hours, the mass fraction of hydrogen peroxide before decomposition was 0.512%, and the mass fraction of hydrogen peroxide after decomposition was 0.004%, with a decomposition rate of 99.2%.

[0069] Example 5

[0070] The catalytic decomposition of hydrogen peroxide in methanol-water solution was carried out using the method of Example 3, except that the catalyst used was catalyst A3 prepared in Preparation Example 3, and the feed mass space-time velocity of the methanol-water solution was 10 h⁻¹. -1 The decomposition temperature is 100℃ and the decomposition pressure is 0.5MPa.

[0071] After continuous feeding for 24 hours, the mass fraction of hydrogen peroxide before decomposition was 0.512%, and the mass fraction of hydrogen peroxide after decomposition was 0.002%, with a decomposition rate of 99.6%.

[0072] Example 6

[0073] The method of Example 3 was used to catalytically decompose hydrogen peroxide in methanol aqueous solution, except that the continuous feeding time was 200 h.

[0074] After continuous feeding for 200 hours, the mass fraction of hydrogen peroxide before decomposition was 0.512%, and the mass fraction of hydrogen peroxide after decomposition was 0.005%, with a decomposition rate of 99.0%.

[0075] The mass content of catalyst components before and after the experiment was analyzed using X-ray fluorescence spectrometry (XRF). Before the experiment, the catalyst contained 5.45% titanium (as TiO2), 44.55% silicon (as SiO2), and 50.00% aluminum (as Al2O3). After 200 hours of continuous feeding, the catalyst contained 5.37% titanium (as TiO2), 44.48% silicon (as SiO2), and 50.15% aluminum (as Al2O3).

[0076] Example 7

[0077] The catalytic decomposition of hydrogen peroxide in a methanol-water solution was carried out using the method of Example 3, except that the methanol-water solution contained 20% by mass of methanol, 0.204% by mass of hydrogen peroxide, and the balance being water.

[0078] After continuous feeding for 24 hours, the mass fraction of hydrogen peroxide before decomposition was 0.204%, and the mass fraction of hydrogen peroxide after decomposition was 0.001%, with a decomposition rate of 99.5%.

[0079] Comparative Example 1

[0080] The catalytic decomposition of hydrogen peroxide in methanol aqueous solution was carried out using the method of Example 3, except that the catalyst used was catalyst B1 prepared in Comparative Preparation Example 1.

[0081] After continuous feeding for 24 hours, the mass fraction of hydrogen peroxide before decomposition was 0.512%, and the mass fraction of hydrogen peroxide after decomposition was 0.003%, with a decomposition rate of 99.4%.

[0082] Comparative Example 2

[0083] The catalytic decomposition of hydrogen peroxide in methanol aqueous solution was carried out using the method of Example 6, except that the catalyst used was catalyst B1 prepared in Comparative Preparation Example 1.

[0084] After continuous feeding for 200 hours, the mass fraction of hydrogen peroxide before decomposition was 0.512%, and the mass fraction of hydrogen peroxide after decomposition was 0.174%, with a decomposition rate of 66.0%.

[0085] The mass content of catalyst components before and after the experiment was analyzed using X-ray fluorescence spectrometry (XRF). Before the experiment, the catalyst contained 54.32% titanium (as TiO2), 6.11% molybdenum (as MoO3), 3.38% copper (as CuO), and 36.19% aluminum (as Al2O3). After 200 hours of continuous feeding, the catalyst contained 56.72% titanium (as TiO2), 2.14% molybdenum (as MoO3), 1.09% copper (as CuO), and 40.05% aluminum (as Al2O3).

[0086] As can be seen from Preparation Examples 1-3 combined with Examples 1-7 and Comparative Examples 1-2, using the method of the present invention and selecting the catalyst with the specific composition and strength of the present invention, after a continuous feeding time of 24-200 hours, the mass fraction of hydrogen peroxide in the methanol aqueous solution can be reduced from 0.5% to below 0.01%, preferably to below 0.005%, with stable catalyst component content and no significant loss or reduction. In contrast, although the comparative method can reduce the mass fraction of hydrogen peroxide in the methanol aqueous solution to below 0.01% in a shorter continuous feeding time, as the continuous feeding time increases, active components such as molybdenum and copper are significantly lost, leading to a significant decrease in the hydrogen peroxide decomposition rate. After 200 hours, the mass fraction of hydrogen peroxide in the methanol aqueous solution reaches 0.174%, which is insufficient to meet the industrial requirements for catalyst strength.

[0087] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for the catalytic decomposition of hydrogen peroxide in an aqueous methanol solution, characterized in that, The method includes the following steps: In the presence of a catalyst, an aqueous methanol solution containing hydrogen peroxide is subjected to a decomposition reaction, wherein the conditions for the decomposition reaction include a temperature of 30-100°C. The catalyst comprises a titanium-silicon molecular sieve with an MFI topology and alumina; based on the total amount of catalyst, the mass fraction of the titanium-silicon molecular sieve with the MFI topology is 40-90%, and the mass fraction of the alumina is 10-60%; the lateral crushing strength of the catalyst is 70-150 N / cm. The methanol-water solution containing hydrogen peroxide is provided by at least one of the following reactions: epoxidation of 3-chloropropene with hydrogen peroxide, epoxidation of propylene with hydrogen peroxide, and hydrogen peroxide production via the anthraquinone process. Based on the total amount of the methanol-water solution containing hydrogen peroxide, the mass fraction of hydrogen peroxide in the methanol-water solution containing hydrogen peroxide is 0.02-1%.

2. The method according to claim 1, wherein, Based on the total amount of catalyst, the mass fraction of the titanium silicate molecular sieve with MFI topology is 50-85%, and the mass fraction of alumina is 15-50%.

3. The method according to claim 1, wherein, The catalyst has a lateral crushing strength of 75-120 N / cm.

4. The method according to any one of claims 1-3, wherein, The alumina is provided by aluminum hydroxide powder and / or aluminum sol.

5. The method according to any one of claims 1-3, wherein, The titanium-silicon molecular sieve with the MFI topology has a titanium-silicon molar ratio of 1:20 to 1:

100.

6. The method according to any one of claims 1-3, wherein, Based on the total amount of the methanol-water solution containing hydrogen peroxide, the mass fraction of hydrogen peroxide in the methanol-water solution containing hydrogen peroxide is 0.05-0.6%.

7. The method according to any one of claims 1-3, wherein, Based on the total amount of the methanol-water solution containing hydrogen peroxide, the mass fraction of methanol in the methanol-water solution containing hydrogen peroxide is 5-95%.

8. The method according to claim 7, wherein, Based on the total amount of the methanol-water solution containing hydrogen peroxide, the mass fraction of methanol in the methanol-water solution containing hydrogen peroxide is 20-80%.

9. The method according to any one of claims 1-3, wherein, The methanol-water solution containing hydrogen peroxide is provided by an epoxidation reaction of 3-chloropropene with hydrogen peroxide.

10. The method according to any one of claims 1-3, wherein, The conditions for the decomposition reaction include a temperature of 40-90℃.

11. The method according to claim 10, wherein, The conditions for the decomposition reaction include a temperature of 50-80℃.

12. The method according to any one of claims 1-3, wherein, The conditions for the decomposition reaction include a pressure of 0.1-1 MPa.

13. The method according to claim 12, wherein, The conditions for the decomposition reaction include a pressure of 0.1-0.5 MPa.

14. The method according to any one of claims 1-3, wherein, The decomposition reaction is carried out in a reaction vessel; Alternatively, the decomposition reaction may be carried out in a fixed-bed reactor.

15. The method according to claim 14, wherein, The amount of catalyst used is 0.1-5% of the mass of the methanol aqueous solution containing hydrogen peroxide.

16. The method according to claim 15, wherein, The amount of catalyst used is 0.1-1% of the mass of the methanol aqueous solution containing hydrogen peroxide.

17. The method of claim 14, wherein, The residence time of the methanol-water solution containing hydrogen peroxide in the reactor is 0.01-24 h.

18. The method according to claim 17, wherein, The residence time of the methanol-water solution containing hydrogen peroxide in the reactor is 0.1-10 h.

19. The method of claim 14, wherein, The feed liquid hourly space velocity (LHSV) of the methanol-water solution containing hydrogen peroxide is 0.01-20 h⁻¹. -1 .

20. The method according to claim 19, wherein, The feed liquid hourly space velocity (LHSV) of the methanol-water solution containing hydrogen peroxide is 0.1-10 h⁻¹. -1 .