A catalyst for preparing epichlorohydrin, preparation method and application thereof

Abstract

The present invention provides a catalyst for preparing epichlorohydrin, a preparation method thereof and an application thereof. The catalyst comprises WO3, titanium silicon molecular sieve, α-Al2O3, calcium silicate and SiO2. The catalyst is formed by extrusion, has high mechanical strength, and good heat transfer and mass transfer performance; the catalysts with different titanium silicon molecular sieve contents are loaded in layers, and have excellent mechanical strength, activity, selectivity and stability when used for epoxidation of 3-chloropropene.

Description

Technical Field

[0001] The invention belongs to the field of catalysts, and in particular relates to a catalyst for preparing epichlorohydrin, a preparation method thereof and an application thereof. Background Art

[0002] Epichlorohydrin is an important organic chemical intermediate, mainly used in the production of epoxy resin. It is also a raw material for manufacturing a variety of adhesives, medicines, pesticides, plasticizers, ion exchange resins and other products. It can also be used as a solvent for coatings, paints, rubber, resins and cellulose ethers, and has broad market prospects.

[0003] The glycerol method consists of two steps of hydrochlorination and saponification, with fewer by-products and mild operating conditions. However, this method still produces wastewater and waste residue, and the production capacity of epichlorohydrin is greatly limited by the raw material glycerol, and the price of the raw material fluctuates greatly.

[0004] The hydrogen peroxide oxidation method uses titanium silicon molecular sieve to catalyze hydrogen peroxide to directly oxidize 3-chloropropylene to prepare epichlorohydrin. This process uses H2O2 as an oxidant, and the production process is simple and less polluting. The only by-product is water. It has the advantages of high selectivity, green environmental protection and relatively safe process. However, the oxidation reaction rate of 3-chloropropylene with hydrogen peroxide in this process is fast, the heat release is large, the temperature difference of the catalyst bed is large, and side reactions are prone to occur. In addition, due to the decomposition of hydrogen peroxide to produce oxygen, the system has the risk of explosion; the liquid phase reaction is a great test on the mechanical strength of the catalyst; the raw material chloropropylene and the product epichlorohydrin are unstable, and side reactions such as hydrolysis, etherification, and polymerization are prone to occur, and the catalyst is easily deactivated.

[0005] Catalyst is one of the core technologies for preparing epichlorohydrin by oxidizing 3-chloropropene with hydrogen peroxide. 3-chloropropene epoxidation catalysts have been reported in many patents, mainly of two types: heteropolyacid salt catalysts and titanium silicon molecular sieve catalysts.

[0006] CN102746257A, CN10839541A and the like disclose methods for preparing epichlorohydrin by catalytic oxidation of 3-chloropropylene by heteropolyacid salts. The heteropolyacid salt catalysts have the disadvantages of high unit consumption, difficulty in recovery and severe corrosion.

[0007] CN1830564A discloses a method for preparing an integral TS-1 catalyst for epoxidation of allyl chloride, wherein a molecular sieve synthesis liquid and a porous ceramic carrier are placed together in a crystallization kettle for crystallization. The catalyst has a low content of titanium silicon molecular sieve, and has low catalyst activity and selectivity (epichlorohydrin selectivity is about 60%).

[0008] CN1114495C discloses the preparation and application of a composite catalyst. The composite catalyst of spherical or irregular particles prepared by extrusion or spray molding is used for epoxidation of 3-chloropropylene to prepare epichlorohydrin. The hydrogen peroxide conversion rate is 72.5% and the epichlorohydrin selectivity is 96.7% after 1h of reaction at 40°C. This patent solves the problem of separation of titanium silicon molecular sieve and product by molding titanium silicon molecular sieve, but molding does not improve the reaction activity and selectivity.

[0009] CN101371989B discloses a titanium silicon molecular sieve catalyst and its preparation method and application. The patent adopts nano-alumina, titanium silicon molecular sieve and aluminum sol extrusion molding. At a reaction temperature of 50°C, the hydrogen peroxide conversion rate is about 97%, and the epichlorohydrin selectivity is about 98%. The presence of alumina with more acidic sites in the catalyst will lead to ineffective decomposition of hydrogen peroxide, promote the occurrence of side reactions such as etherification, and have an adverse effect on the stability of the catalyst.

[0010] The above patent does not mention the effects of catalyst formulation and process on the activity, selectivity and stability of 3-chloropropene epoxidation.

[0011] At present, the catalyst for oxidizing 3-chloropropylene with hydrogen peroxide prepared by the prior art has the problems of high catalyst production cost, low activity, poor selectivity and stability. Therefore, it is necessary to develop a catalyst with excellent activity, selectivity, stability and low production cost. Summary of the invention

[0012] The purpose of the present invention is to provide a catalyst for preparing epichlorohydrin by oxidizing 3-chloropropylene with hydrogen peroxide and a preparation method thereof. The catalyst prepared by this patent has excellent activity and selectivity.

[0013] To achieve the above object, the present invention adopts the following technical solution:

[0014] A catalyst for preparing epichlorohydrin by oxidizing 3-chloropropylene with hydrogen peroxide, wherein the catalyst comprises the following components based on the total mass of the catalyst as 100wt%:

[0015]

[0016] During the preparation of the catalyst of the present invention, alpha-alumina and calcium silicate with special particle sizes are added, which effectively improves the mass transfer performance of the catalyst, reduces the acidity of the catalyst, inhibits the occurrence of side reactions such as polymerization and etherification, and is beneficial to improving the activity, selectivity and stability of the catalyst; the prepared catalysts with different contents of titanium silicate molecular sieves are loaded in layers, which effectively controls the hot spot temperature of the bed, and is beneficial to the selectivity and stability of the catalyst; the titanium silicate molecular sieve is expensive, and the addition of alpha-alumina and calcium silicate in the catalyst not only improves the catalyst performance, but also effectively reduces the production cost of the catalyst; the titanium silicate molecular sieve has high activity, but the pores are small and easy to deactivate, and W has certain epoxidation activity. The introduction of W can not only improve the activity of the catalyst, but also allyl chloride can be converted to a certain extent before entering the pores of the molecular sieve, which is beneficial to improving the stability of the catalyst.

[0017] Another object of the present invention is to provide a method for preparing the catalyst.

[0018] A method for preparing the catalyst according to claim 1, the method comprising the following steps:

[0019] S1: mixing titanium silicon molecular sieve, calcium silicate, α-Al2O3 and sesbania powder as an extrusion aid to obtain a mixed powder;

[0020] S2: mixing the tungsten compound-containing aqueous solution with silica sol to obtain a mixed solution;

[0021] S3: kneading the mixed powder of S1 and the mixed solution of S2, extruding and cutting into particles;

[0022] S4: Drying and calcining the particles of S3 to obtain a catalyst.

[0023] In the present invention, the titanium content in the titanium silicon molecular sieve described in S1 is 1.0-3.0 wt%.

[0024] In the present invention, the particle size of the α-alumina described in S1 is 80-150 mesh.

[0025] In the present invention, the particle size of the calcium silicate described in S1 is 50-100 nm; preferably, the mass of the calcium silicate is 5.0-50.0% of the mass of the titanium silicon molecular sieve.

[0026] In the present invention, the silica sol described in S2 is an ammonia type silica sol, preferably the concentration of the silica sol is 20-40wt%, and the particle size is 20-30nm. The silica sol in S2 is a binder required for the extrusion process, and is converted into SiO2 after calcination.

[0027] In the present invention, the tungsten-containing compound described in S2 is ammonium metatungstate and / or sodium metatungstate; preferably, the concentration of the aqueous solution of the tungsten-containing compound is 10-60wt%.

[0028] In the present invention, the particles described in S3 are pentagonal, and the diameter of the circumscribed circle of the particles is 1.0-3.0 mm and the length is 1.0-3.0 mm.

[0029] In the present invention, the drying temperature in step S4 is 100-120° C., and the drying time is 4-12 hours; the roasting temperature is 350-600° C., and the roasting time is 2-8 hours.

[0030] Another object of the present invention is to provide a method for preparing epichlorohydrin by oxidizing 3-chloropropylene with hydrogen peroxide.

[0031] A method for preparing epichlorohydrin by oxidizing 3-chloropropylene with hydrogen peroxide, the method using the above catalyst, or the catalyst prepared by the above preparation method, the catalyst is loaded from bottom to top in the reactor according to the titanium silicon molecular sieve content in the catalyst from high to low, and the catalyst is loaded in 3-6 layers.

[0032] In the method of the present invention, the catalyst loading method is: the catalyst is loaded in the reaction tube in equal proportions from the bottom to the top of the reactor according to the titanium silicon molecular sieve content from high to low, and the catalyst is loaded in 3-6 layers. The catalyst with low titanium silicon molecular sieve content is loaded on the upper part of the reactor bed, which is beneficial to controlling the heat release of the reaction, reducing the hot spot temperature of the bed, and is beneficial to the reaction selectivity and catalyst stability; the catalyst with high titanium silicon molecular sieve content is loaded on the bottom of the reactor, which is beneficial to improving the conversion rate of hydrogen peroxide and reducing the safety risks of subsequent separation and wastewater treatment processes.

[0033] In one embodiment, the process conditions for the catalyst to be used in the oxidation of 3-chloropropylene with hydrogen peroxide to produce epichlorohydrin are:

[0034] The catalyst was evaluated using a fixed bed tubular reactor (using jacketed circulating water for heat transfer), with an inner diameter of 40 mm, a catalyst loading of 100 cm3, and an initial circulating water temperature of 20 °C. The molar ratio of raw materials of allyl chloride, methanol, and hydrogen peroxide was (2-5): (5-10): 1, the reaction pressure was 1.0 MPaG, and the H2O2 space velocity was 0.2 h -1 After the reaction feed has stabilized for 2-4 hours, samples were taken for analysis.

[0035] Compared with the prior art, the beneficial effects of the present invention are:

[0036] The prepared catalyst has weak acidity and good mass transfer performance, and the catalysts with different titanium silicon molecular sieve contents are loaded in stages, and have excellent activity, selectivity and stability. The H2O2 conversion rate is greater than 99.5%, and the epichlorohydrin selectivity is greater than 98.5%. After running for 2000 hours, the H2O2 conversion rate is still greater than 99.0%. DETAILED DESCRIPTION

[0037] In order to understand the technical features and contents of the present invention in detail, the preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described in the embodiments, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described here.

[0038] <Source of raw materials>

[0039] Methanol, analytical grade, purity >99.5%, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0040] 50% hydrogen peroxide, industrial grade, Beijing Inokai Technology Co., Ltd.;

[0041] Ammonium metatungstate, analytical grade, Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0042] Sodium tungstate, analytical grade, Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0043] Allyl chloride, analytical grade, Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0044] Titanium silicate molecular sieve, model NKF-8, Tianjin Nanhua Catalyst Co., Ltd.;

[0045] Calcium silicate, Beijing Inokai Technology Co., Ltd., particle size 50-100 nm;

[0046] α-alumina powder, Beijing Inokai Technology Co., Ltd., particle size 80-150 mesh;

[0047] Silica sol, pH 8-9, Shandong Better New Materials Co., Ltd.;

[0048] Sesbania powder, model SG1, Beijing Inokai Technology Co., Ltd.

[0049] <Test Method>

[0050] The H2O2 utilization rate and epichlorohydrin selectivity were calculated after analysis using an Agilent 7820A gas chromatograph. The test conditions included: a PONA column, a FID detector, a vaporization chamber temperature of 220°C, a detector temperature of 240°C, high-purity N2 as the carrier gas, and a flow rate of 30 ml / min.

[0051] The hydrogen peroxide content was detected by iodine titration: 0.5 g of the reaction solution was added with 1 g of potassium iodide, mixed evenly for 5 minutes in the dark, and then potentiometric titration was performed with sodium thiosulfate.

[0052] Selectivity of epichlorohydrin = the number of moles of allyl chloride corresponding to epichlorohydrin produced / the number of moles of allyl chloride converted × 100%;

[0053] Hydrogen peroxide conversion rate = number of moles of hydrogen peroxide converted / number of moles of hydrogen peroxide input × 100%;

[0054] Hydrogen peroxide utilization rate = moles of epichlorohydrin and hydrogen peroxide corresponding to by-products / moles of converted hydrogen peroxide × 100%.

[0055] Extruder model: F-26, manufacturer: Guangzhou Huagong Optoelectronics Technology Co., Ltd.;

[0056] Kneading machine model: FNH-1L powder kneading machine, manufacturer: Guangzhou Huagong Optoelectronic Technology Co., Ltd.;

[0057] The fixed bed tubular reactor has an inner diameter of 40 mm and a length of 1.2 m. Manufacturer: Yantai Keli Chemical Equipment Co., Ltd.

[0058] Example 1

[0059] Catalyst C1 preparation:

[0060] S1: 60.0 g of titanium silicate molecular sieve (Ti content 2.0%), 60.0 g of α-alumina, 28.0 g of calcium silicate and 3.0 g of sesbania powder were fully mixed in a kneader FNH-1L for 20 minutes to obtain mixed powder A1.

[0061] S2: 17.78 g of 40 wt % sodium tungstate aqueous solution was added to 156.7 g (30 wt %, 20-30 nm) of silica sol, and the mixture was stirred in a 500 ml glass flask to obtain a mixed solution B1.

[0062] S3: The mixed powder A1 of step (1) and the mixed solution B1 of step (2) are fully kneaded in a kneading machine FNH-1L for 30 minutes (A1 is mixed with B1, and so on), extruded and cut into pellets. The pellets are five-tooth shaped, with a diameter of 2.5 mm and a length of 2.5 mm.

[0063] S4: The above particles were dried at 120° C. for 4 h and calcined at 550° C. for 4 h to obtain catalyst C1, which contained 30 wt % of titanium silicon molecular sieve.

[0064] Catalyst C2 preparation:

[0065] S1: 96.0 g of titanium silicate molecular sieve (Ti content 2.0%), 40.0 g of α-alumina, 20.0 g of calcium silicate and 3.0 g of sesbania powder were fully mixed in a kneader FNH-1L for 20 minutes to obtain mixed powder A2.

[0066] S2: 10.67 g of 40 wt % sodium tungstate aqueous solution was added to 136.7 g (30 wt %, 20-30 nm) of silica sol, and the mixture was stirred in a 500 ml glass flask to obtain a mixed solution B2.

[0067] S3: The mixed powder A2 of step (1) and the mixed solution B2 of step (2) are fully kneaded in a kneading machine FNH-1L for 30 minutes, extruded and cut into pellets. The pellets are five-tooth shaped, with a diameter of 2.5 mm and a length of 2.5 mm.

[0068] S4: The above particles were dried at 120°C for 4 hours and calcined at 550°C for 4 hours to obtain catalyst C2, which contained 48 wt% of titanium silicon molecular sieve.

[0069] Catalyst C3 preparation:

[0070] S1: 130.0 g of titanium silicate molecular sieve (Ti content 2.0%), 20.0 g of α-alumina, 10.0 g of calcium silicate and 3.0 g of sesbania powder were fully mixed in a kneader FNH-1L for 20 minutes to obtain a mixed powder A3.

[0071] S2: 3.56 g of 40 wt % sodium tungstate aqueous solution was added to 195.0 g (20 wt %, 20-30 nm) of silica sol, and the mixture was stirred in a 500 ml glass flask to obtain a mixed solution B3.

[0072] S3: The mixed powder A3 of step (1) and the mixed solution B3 of step (2) are fully kneaded in a kneading machine FNH-1L for 30 minutes, extruded and cut into pellets. The pellets are five-tooth shaped, with a diameter of 2.5 mm and a length of 2.5 mm.

[0073] S4: The above particles were dried at 120°C for 4 hours and calcined at 550°C for 4 hours to obtain catalyst C3, which contained 65 wt% of titanium silicon molecular sieve.

[0074] Catalyst performance evaluation:

[0075] The catalyst was evaluated using a fixed-bed tubular reactor (using jacketed circulating water for heat transfer). The inner diameter of the reaction tube was 40 mm. From top to bottom, the first / second / third layers of catalyst were each loaded with 33.3 cm of catalyst C1 / C2 / C3. The molar ratio of raw materials, propylene chloride, methanol and H2O2 was 2:10:1. The initial setting temperature of the circulating water was 20 °C, the reaction pressure was 1.0 MPaG, and the space velocity was 0.2 h in terms of H2O2. -1 (The concentration of H2O2 in hydrogen peroxide is 50 wt%). After the reaction feed was stable for 4 hours, a sample was taken for analysis. The reaction results are shown in Table 1.

[0076] Example 2

[0077] Catalyst F1 preparation:

[0078] S1: 70.0 g of titanium silicate molecular sieve (Ti content 1.5%), 60.0 g of α-alumina, 24.0 g of calcium silicate and 3.0 g of sesbania powder were fully mixed in a kneader FNH-1L for 20 minutes to obtain a mixed powder D1.

[0079] S2: 23.52 g of 20 wt % aqueous solution of ammonium metatungstate was added to 138.7 g (30 wt %, 20-30 nm) of silica sol, and the mixture was stirred in a 500 ml glass flask to obtain a mixed solution E1.

[0080] S3: The mixed powder D1 of step (1) and the mixed solution E1 of step (2) are fully kneaded in a kneading machine FNH-1L for 30 minutes, extruded and cut into pellets. The pellets are five-tooth shaped, with a diameter of 2.0 mm and a length of 2.0 mm.

[0081] S4: The above particles were dried at 110° C. for 8 h and calcined at 500° C. for 4 h to obtain catalyst F1, which contained 35 wt % of titanium silicon molecular sieve.

[0082] Catalyst F2 preparation:

[0083] S1: 100.0 g of titanium silicate molecular sieve (Ti content 1.5%), 32.0 g of α-alumina, 20.0 g of calcium silicate and 3.0 g of sesbania powder were fully mixed in a kneader FNH-1L for 20 minutes to obtain a mixed powder D2.

[0084] S2: 13.90 g of 20 wt % aqueous solution of ammonium metatungstate was added to 151.3 g (30 wt %, 20-30 nm) of silica sol, and the mixture was stirred in a 500 ml glass flask to obtain a mixed solution E2.

[0085] S3: The mixed powder D2 of step (1) and the mixed solution E2 of step (2) are fully kneaded in a kneading machine FNH-1L for 30 minutes, extruded and cut into pellets. The pellets are five-tooth shaped, with a diameter of 2.0 mm and a length of 2.0 mm.

[0086] S4: The above particles are dried at 120° C. for 4 h and calcined at 550° C. for 4 h to obtain catalyst F2, which contains 50 wt % of titanium silicon molecular sieve.

[0087] Catalyst F3 preparation:

[0088] S1: 126.0 g of titanium silicate molecular sieve (Ti content 1.5%), 24.0 g of α-alumina, 10.0 g of calcium silicate and 3.0 g of sesbania powder were fully mixed in a kneader FNH-1L for 20 minutes to obtain a mixed powder D3.

[0089] S2: 8.55 g of 20 wt % aqueous solution of ammonium metatungstate was added to 153.6 g (25 wt %, 20-30 nm) of silica sol, and the mixture was stirred in a 500 ml glass flask to obtain a mixed solution E3.

[0090] S3: The mixed powder D3 of step (1) and the mixed solution E3 of step (2) are fully kneaded in a kneading machine FNH-1L for 30 minutes, extruded and cut into pellets. The pellets are five-tooth shaped, with a diameter of 2.0 mm and a length of 2.0 mm.

[0091] S4: The above particles were dried at 120°C for 4 hours and calcined at 550°C for 4 hours to obtain catalyst F3, which contained 63 wt% of titanium silicon molecular sieve.

[0092] The catalyst was evaluated using a fixed bed tubular reactor (using jacketed circulating water for heat transfer) with an inner diameter of 40 mm. The first / second / third layers of catalyst from top to bottom were each loaded with 33.3 cm of catalyst F1 / F2 / F3. Other evaluation conditions were the same as in Example 1. The reaction results are shown in Example 2-1 in Table 1.

[0093] The catalyst was evaluated using a fixed-bed tubular reactor (using jacketed circulating water for heat transfer). The inner diameter of the reaction tube was 40 mm. From top to bottom, the first / second / third layers of catalyst were each loaded with 33.3 cm of catalyst F1 / F2 / F3. The molar ratio of raw materials, propylene chloride, methanol and H2O2 was 3:8:1. The initial setting temperature of the circulating water was 20 °C, the reaction pressure was 1.0 MPaG, and the space velocity was 0.3 h in terms of H2O2. -1 (The concentration of H2O2 in hydrogen peroxide is 50 wt%). After the reaction feed is stable for 4 hours, a sample is taken for analysis. The reaction results are shown in Example 2-2 in Table 1.

[0094] The catalyst was evaluated using a fixed-bed tubular reactor (using jacketed circulating water for heat transfer). The inner diameter of the reaction tube was 40 mm. The first / second / third layers of catalyst from top to bottom were each loaded with 33.3 cm of catalyst F1 / F2 / F3. The molar ratio of raw materials, propylene chloride, methanol and H2O2 was 4:9:1. The initial setting temperature of the circulating water was 20 °C, the reaction pressure was 1.0 MPaG, and the space velocity in terms of H2O2 was 0.3 h -1 (The concentration of H2O2 in hydrogen peroxide is 50 wt%). After the reaction feed is stable for 4 hours, a sample is taken for analysis. The reaction results are shown in Example 2-3 in Table 1.

[0095] Example 3

[0096] Catalyst I1 preparation:

[0097] S1: 66.0 g of titanium silicate molecular sieve (Ti content: 2.5%), 64.0 g of α-alumina, 20.0 g of calcium silicate and 3.0 g of sesbania powder were fully mixed in a kneader FNH-1L for 20 minutes to obtain a mixed powder G1.

[0098] S2: 11.97 g of 50 wt % aqueous solution of ammonium metatungstate was added to 148.0 g (30 wt %, 20-30 nm) of silica sol, and the mixture was stirred in a 500 ml glass flask to obtain a mixed solution H1.

[0099] S3: The mixed powder G2 of step (1) and the mixed solution H2 of step (2) are fully kneaded in a kneading machine FNH-1L for 30 minutes, extruded and cut into pellets. The pellets are five-tooth shaped, with a diameter of 2.0 mm and a length of 2.0 mm.

[0100] S4: The above particles were dried at 100°C for 12 hours and calcined at 500°C for 8 hours to obtain catalyst I1, which contained 33 wt% of titanium silicon molecular sieve.

[0101] Catalyst I2 preparation:

[0102] S1: 76.0 g of titanium silicate molecular sieve (Ti content 2.5%), 52.0 g of α-alumina, 16.0 g of calcium silicate and 3.0 g of sesbania powder were fully mixed in a kneader FNH-1L for 20 minutes to obtain a mixed powder G2.

[0103] S2: 9.41 g of a 50 wt % aqueous solution of ammonium metatungstate was added to 172.0 g (30 wt %, 20-30 nm) of silica sol, and the mixture was stirred in a 500 ml glass flask to obtain a mixed solution H2.

[0104] S3: The mixed powder G2 of step (1) and the mixed solution H2 of step (2) are fully kneaded in a kneading machine FNH-1L for 30 minutes, extruded and cut into pellets. The pellets are five-tooth shaped, with a diameter of 2.0 mm and a length of 2.0 mm.

[0105] S4: The above particles were dried at 100°C for 12 hours and calcined at 500°C for 8 hours to obtain catalyst I2, which contained 38 wt% of titanium silicon molecular sieve.

[0106] Catalyst I3 preparation:

[0107] S1: 96.0 g of titanium silicate molecular sieve (Ti content: 2.5%), 40.0 g of α-alumina, 20.0 g of calcium silicate and 3.0 g of sesbania powder were fully mixed in a kneader FNH-1L for 20 minutes to obtain a mixed powder G3.

[0108] S2: 7.70 g of a 50 wt % aqueous solution of ammonium metatungstate was added to 161.6 g (25 wt %, 20-30 nm) of silica sol, and the mixture was stirred in a 500 ml glass flask to obtain a mixed solution H3.

[0109] S3: The mixed powder G3 of step (1) and the mixed solution H3 of step (2) are fully kneaded in a kneading machine FNH-1L for 30 minutes, extruded and cut into pellets. The pellets are five-tooth shaped, with a diameter of 2.0 mm and a length of 2.0 mm.

[0110] S4: The above particles were dried at 100°C for 12 hours and calcined at 500°C for 8 hours to obtain catalyst I3, which contained 48 wt% of titanium silicon molecular sieve.

[0111] Catalyst I4 preparation:

[0112] S1: 104.0 g of titanium silicate molecular sieve (Ti content: 2.5%), 32.0 g of α-alumina, 12.0 g of calcium silicate and 3.0 g of sesbania powder were fully mixed in a kneader FNH-1L for 20 minutes to obtain a mixed powder G4.

[0113] S2: 6.41 g of 50 wt % aqueous solution of ammonium metatungstate was added to 196.0 g (25 wt %, 20-30 nm) of silica sol, and the mixture was stirred in a 500 ml glass flask to obtain a mixed solution H4.

[0114] S3: The mixed powder G4 of step (1) and the mixed solution H4 of step (2) are fully kneaded in a kneading machine FNH-1L for 30 minutes, extruded and cut into pellets. The pellets are five-tooth shaped, with a diameter of 2.0 mm and a length of 2.0 mm.

[0115] S4: The above particles were dried at 100°C for 10 h and calcined at 500°C for 4 h to obtain catalyst I4, which contained 52 wt% of titanium silicon molecular sieve.

[0116] Catalyst I5 preparation:

[0117] S1: 116.0 g of titanium silicate molecular sieve (Ti content: 2.5%), 24.0 g of α-alumina, 24.0 g of calcium silicate and 3.0 g of sesbania powder were fully mixed in a kneader FNH-1L for 20 minutes to obtain a mixed powder G5.

[0118] S2: 2.57 g of 50 wt % aqueous solution of ammonium metatungstate was added to 116.0 g (25 wt %, 20-30 nm) of silica sol, and the mixture was stirred in a 500 ml glass flask to obtain a mixed solution H5.

[0119] S3: The mixed powder G5 of step (1) and the mixed solution H5 of step (2) are fully kneaded in a kneading machine FNH-1L for 30 minutes, extruded and cut into pellets. The pellets are five-tooth shaped, with a diameter of 2.0 mm and a length of 2.0 mm.

[0120] S4: The above particles were dried at 100°C for 8 hours and calcined at 500°C for 6 hours to obtain catalyst I5, which contained 58 wt% of titanium silicon molecular sieve.

[0121] The catalyst was evaluated using a fixed bed tubular reactor (using jacketed circulating water for heat transfer) with an inner diameter of 40 mm. From top to bottom, the first / second / third / fourth / fifth catalyst layer was each loaded with 20.0 cm of catalyst I1 / I2 / I3 / I4 / I5. Other evaluation conditions were the same as in Example 1.

[0122] Comparative Example 1

[0123] The catalyst bed was fully filled with the first layer catalyst C1 prepared in Example 1.

[0124] The catalyst evaluation method is the same as in Example 1.

[0125] Comparative Example 2

[0126] The catalyst bed was fully loaded with the third layer catalyst C3 prepared in Example 1.

[0127] The catalyst evaluation method is the same as in Example 1.

[0128] Comparative Example 3

[0129] No α-alumina was added during the catalyst extrusion molding, and the rest was the same as in Example 1.

[0130] Comparative Example 4

[0131] No calcium silicate was added during the catalyst extrusion molding, and the rest was the same as in Example 1.

[0132] Comparative Example 5

[0133] No aqueous ammonium metatungstate solution was added during the catalyst extrusion molding, and the other conditions were the same as in Example 1.

[0134] Table 1 Catalyst evaluation results

[0135]

[0136] As shown in Table 1, the catalysts described in Examples 1 / 2 / 3 have good activity, selectivity and stability, while the catalysts described in Comparative Examples 1 to 4 have low activity, poor selectivity or poor stability. The above results show that the catalyst prepared by the present invention has smooth pores, good heat transfer and mass transfer performance, and the catalyst composite loading is used for H2O2 oxidation of 3-chloropropylene to prepare epichlorohydrin, and has not only excellent activity and selectivity, but also good stability.

[0137] Comparison between Example 1 and Comparative Example 1 shows that the H2O2 conversion rate is low when only a catalyst with a low titanium silicon molecular sieve content is used.

[0138] Comparison between Example 1 and Comparative Example 2 shows that when only a catalyst with a high content of titanium silicon molecular sieve is used, the hot spot temperature of the bed is high, which will lead to low effective utilization of hydrogen peroxide, poor selectivity of epichlorohydrin, and poor catalyst stability.

[0139] Comparison between Example 1 and Comparative Example 3 shows that adding α-alumina (80-150 mesh) to the catalyst is beneficial to improving the heat transfer and mass transfer performance of the catalyst and increasing the activity, selectivity and stability of the catalyst.

[0140] Comparison between Example 1 and Comparative Example 4 shows that the introduction of calcium silicate into the catalyst improves the selectivity and stability of the catalyst.

[0141] Comparison between Example 1 and Comparative Example 5 shows that the introduction of W into the catalyst improves the activity and stability of the catalyst.

Claims

1. A catalyst for preparing epichlorohydrin by oxidizing 3-chloropropylene with hydrogen peroxide, characterized in that: Taking the total mass of the catalyst as 100wt%, the catalyst comprises the following components: Wherein, the particle size of the α-Al2O3 is 80-150 mesh.

2. A method for preparing the catalyst according to claim 1, characterized in that: The method comprises the following steps: S1: mixing titanium silicon molecular sieve, calcium silicate, α-Al2O3 and sesbania powder as an extrusion aid to obtain a mixed powder; S2: mixing the tungsten compound-containing aqueous solution with the silica sol to obtain a mixed solution; S3: kneading the mixed powder of S1 and the mixed solution of S2, extruding and cutting into particles; S4: Drying and calcining the particles of S3 to obtain a catalyst.

3. The method according to claim 2, characterized in that The titanium content of the titanium silicon molecular sieve described in S1 is 1.0-3.0wt%; And / or, the particle size of the α-alumina described in S1 is 80-150 mesh; And / or, the calcium silicate particle size described in S1 is 50-100 nm.

4. The method according to claim 3, characterized in that The mass of the calcium silicate in S1 is 5.0-50.0% of the mass of the titanium silicate molecular sieve.

5. The method according to claim 2, characterized in that: The silica sol described in S2 is an ammonia type silica sol; And / or, the tungsten-containing compound described in S2 is ammonium metatungstate and / or sodium tungstate.

6. The method according to claim 5, characterized in that The concentration of the silica sol described in S2 is 20-40wt% and the particle size is 20-30nm; S2 The concentration of the aqueous solution containing tungsten compound is 10-60wt%.

7. The method according to claim 2, characterized in that The particles described in S3 are pentagonal in shape, and the diameter of the circumscribed circle of the particles is 1.0-3.0 mm and the length is 1.0-3.0 mm.

8. The method according to claim 2, characterized in that: The drying temperature in S4 is 100-120°C, and the drying time is 4-12h; the roasting temperature is 350-600°C, and the roasting time is 2-8h; And / or, S4 prepares catalysts with titanium silicon molecular sieve contents of 30-45%, 45-55% and 55-65%, respectively.

9. A method for preparing epichlorohydrin by oxidizing 3-chloropropylene with hydrogen peroxide, the method using the catalyst of claim 1, or the catalyst prepared by the preparation method of any one of claims 2 to 8, characterized in that: The catalyst is loaded in the reactor from bottom to top according to the titanium silicon molecular sieve content in the catalyst from high to low, and the catalyst is loaded in 3-6 layers.

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