阅读说明：本技术 一种薄层纳米片型多级孔ts-1分子筛催化剂的制备方法及其应用 (Preparation method and application of thin-layer nanosheet type hierarchical pore TS-1 molecular sieve catalyst ) 是由 徐林 邓生财 黄杰军 丁克鸿 胡金良 于 2020-11-25 设计创作，主要内容包括：本发明提供了一种高稳定性、高活性的纳米片型多级孔核壳结构TS-1分子筛催化剂的制备方法及其应用。TS-1催化剂核层为纳米片型多级孔TS-1分子筛,催化剂壳层为纯硅分子筛Silicalite-1。通过多级孔TS-1纳米片型分子筛催化剂的构建,可消除传统颗粒型钛硅分子筛孔道存在的内扩散限制问题,通过表面构建纯硅分子筛Silicalite-1壳层可降低常规TS-1分子筛的表面酸性,抑制开环副产物的生成。该催化剂可应用于氯丙烯双氧水法合成环氧氯丙烷的反应,可有效提高环氧氯丙烷的选择性和催化剂的使用寿命。(The invention provides a preparation method and application of a nanosheet type hierarchical pore core-shell structure TS-1 molecular sieve catalyst with high stability and high activity. The core layer of the TS-1 catalyst is a nano-sheet type hierarchical pore TS-1 molecular sieve, and the shell layer of the catalyst is a pure silicon molecular sieve Silicalite-1. By constructing the multi-stage pore TS-1 nano sheet type molecular sieve catalyst, the problem of internal diffusion limitation existing in the pore channel of the traditional granular titanium Silicalite molecular sieve can be solved, and the surface acidity of the conventional TS-1 molecular sieve can be reduced and the generation of ring-opening byproducts can be inhibited by constructing a pure Silicalite-1 shell layer on the surface. The catalyst can be applied to the reaction of synthesizing epoxy chloropropane by a chloropropene dioxygen water method, and can effectively improve the selectivity of the epoxy chloropropane and prolong the service life of the catalyst.)

1. A preparation method of core-shell structure hierarchical pore nano-sheet [email protected] TS-1 is characterized in that,

(1) adding a mixed solution of Tetraethoxysilane (TEOS) and tetrapropylammonium hydroxide into a glass reaction kettle, violently stirring for 30-50min to form transparent sol, hydrolyzing at 65-95 ℃ for 1-2h to form prehydrolyzed silica sol, and dropwise adding quaternary ammonium salt to obtain tetraethoxysilane hydrolysate;

(2) dropwise adding a certain amount of tetrabutyl titanate (TBOT)/isopropanol solution into the tetraethoxysilane hydrolysate obtained in the step 1, slowly dropwise adding while stirring, after dropwise adding, heating to 55-85 ℃, further hydrolyzing for 4-6h, and then transferring to a hydrothermal kettle at 180 ℃ for crystallization for 48-96 h to obtain TS-1 nanosheets;

(3) centrifuging, separating and drying the TS-1 nanosheets subjected to the hydrothermal crystallization in the step 2 to obtain nanosheet type TS-1 molecular sieve seed crystals;

(4) transferring TS-1 molecular sieve seed crystals to Silicalite-1 prehydrolysis liquid, and crystallizing for 24-72 hours in a crystallization kettle at 180 ℃;

(5) obtaining the titanium silicalite molecular sieve after centrifugal separation, washing and drying;

(6) transferring the molecular sieve into a muffle furnace, heating to 550 ℃ at the speed of 2-5 ℃/min, roasting, and keeping the temperature for 5-7 hours to obtain a [email protected] TS-1 molecular sieve;

(7) transferring the calcined molecular sieve into [email protected] TS-1 molecular sieve, TPAOH, H₂Performing secondary crystallization in the solution of O, wherein the hydrothermal temperature of a secondary crystallization kettle is controlled to be 150-170 ℃, and performing continuous hydrothermal crystallization for 12-48 h to obtain a hierarchical pore nano sheet type catalyst [email protected] TS-1 with a hierarchical pore core-shell structure;

(8) taking 10g [email protected] TS-1 molecular sieve and SiO₂，NH₄HF₂，H₂And (3) uniformly mixing the O, heating to 50-100 ℃, and stirring for 4-12 hours to obtain the [email protected] TS-1 catalyst.

2. The preparation method of the core-shell structure hierarchical pore nano-sheet type [email protected] TS-1 as claimed in claim 1, wherein the molar ratio of the ethyl orthosilicate to the tetrapropylammonium hydroxide in the step (1) is in the range of: 1:1-5:1, wherein the molar ratio of the ethyl orthosilicate to the quaternary ammonium salt is 4:1-10:1, and the quaternary ammonium salt is one of alkyl dimethyl hydroxyethyl quaternary ammonium salt, alkyl triethylene diamine derivative and tetrapropenyl ammonium hydroxide quaternary ammonium salt.

3. The preparation method of the core-shell structure hierarchical pore nano-sheet type [email protected] TS-1 as claimed in claim 1, wherein the molar ratio of the ethyl orthosilicate, the tetrabutyl titanate and the isopropanol in the step (2) is in the range of: 10:1: 10-20:1:15.

4. The preparation method of the core-shell structure hierarchical pore nano-sheet type [email protected] TS-1 as claimed in claim 1, wherein in the step (4), the Silicalite-1 prehydrolysis liquid contains Tetraethoxysilane (TEOS): tetrapropylammonium hydroxide (TPAOH): h₂The molar ratio of O is 20: 14: 9500 the mass ratio of the TS-1 molecular sieve seed crystal to the hydrolysate is controlled at 1-2 wt.%.

5. The preparation method of the core-shell structure hierarchical pore nano-sheet type [email protected] TS-1 as claimed in claim 1, wherein the solution in the step (7) is 100g of [email protected] TS-1 molecular sieve, 5-20 g of TPAOH, and 55mol of H₂O。

6. The preparation method of the core-shell structure hierarchical pore nano-sheet type [email protected] TS-1 as claimed in claim 1, wherein in the step (8), SiO is added₂：NH₄HF₂：H₂The molar ratio of O is 100: 25: 3000.

Technical Field

The invention provides a method for synthesizing epichlorohydrin by using a nanosheet core-shell structure catalyst [email protected] TS-1 with high stability and high activity, wherein a catalyst core layer is TS-1 with a nanosheet structure, a catalyst shell layer is a pure silicon molecular sieve Silicalite-1, the acid sites on the surface of the molecular sieve can be reduced through the construction of the pure silicon molecular sieve Silicalite-1, the generation of ring-opening byproducts is inhibited, and the mass transfer efficiency can be effectively improved and the stability of the catalyst is further improved through the construction of multi-level holes in the nanosheets. The catalyst can be applied to the epoxidation of halogenated olefin, in particular to the reaction of synthesizing epoxy chloropropane by a chloropropene dioxygen water method, can effectively improve the selectivity of the epoxy chloropropane and prolong the service life of the catalyst, and belongs to the field of refinement.

Background

Epichlorohydrin is an important organic chemical raw material and a fine chemical product, and epoxy resin synthesized by using epichlorohydrin as a raw material has the characteristics of strong chemical medium corrosion resistance, strong cohesiveness, good chemical stability and the like, and has wide application in adhesives, coatings, casting materials and reinforcing materials; epichlorohydrin can also be used for synthesizing various products such as surfactant, electrical insulator, nitroglycerin explosive, glass fiber reinforced plastic, medicine, pesticide, coating, plasticizer, glycidyl derivative, chlorohydrin rubber and the like. The main stream production method of epichlorohydrin comprises a propylene high-temperature chlorination method (chlorohydrin method), a glycerol chlorination method and an acetate propylene ester method, wherein the propylene high-temperature chlorination method accounts for 90% of the global yield, and the synthesis process mainly comprises the steps of preparing chloropropene by propylene high-temperature chlorination, preparing dichloropropanol by chloropropene hypochlorination and preparing epichlorohydrin by dichloropropanol saponification; the glycerol method accounts for about 10% of the global yield, the method avoids the use of highly toxic gas chlorine, the reaction condition is mild, the safety performance of the system is improved, the anti-corrosion performance requirement of the device is reduced, but the process also relates to the problems of resource recovery and utilization of saponified waste salt and wastewater. In order to effectively solve the problem of intermediate production of epoxy chloropropanePreparation, environmental protection, cost and the like, realizes clean process and low production cost, and a patent U.S. Pat. No.4833260 proposes that TS-1 with MFI topological structure is taken as a catalyst H₂O₂A process for preparing an olefin epoxidation product for use as an oxidant. At present, the structure-activity relationship research aiming at the titanium silicalite molecular sieve catalyst shows that the particle size of titanium silicalite TS-1 particles synthesized by the conventional hydrothermal method is between 100nm and 300nm, the catalytic activity of the catalyst can be reduced due to the intra-channel diffusion confinement effect and the channel blockage caused by byproduct high polymers, the intra-diffusion performance can be effectively adjusted by constructing a hollow molecular sieve or constructing a hierarchical molecular sieve, and the stability and the activity of the molecular sieve catalyst are improved. Patent U.S. Pat. No.4410501 discloses a synthesis method of titanium-silicon molecular sieve TS-1 by using silicon source, titanium source and template agent, the molecular sieve synthesized by the method has larger crystal grain, and the reduction of the reaction activity is faster when the method is applied to conventional epichlorohydrin. Patent U.S. Pat. No. us4833260 discloses a method for producing epichlorohydrin by using hydrogen peroxide and using a titanium silicalite molecular sieve as a catalyst, wherein the titanium silicalite molecular sieve synthesized by a hydrothermal method is used as the catalyst, and hydrogen peroxide is used as an oxidant to efficiently oxidize a series of olefin compounds including ethylene, propylene, chloropropene, cyclohexene and the like to prepare corresponding epoxy compounds.

Disclosure of Invention

Aiming at the problems of internal diffusion limitation of the traditional TS-1 molecular sieve, easy inactivation of the catalyst and low activity, the invention constructs the hierarchical porous thin-layer nano sheet type [email protected] TS-1 catalyst with the core-shell structure, so that the internal diffusion limitation can be eliminated, and the internal diffusion rate of the catalyst is greatly enhanced; in addition, the service life of the catalyst can be greatly prolonged and the stability of the catalyst can be improved by inhibiting the surface acidity of the catalyst.

The invention aims to provide a preparation method of core-shell structure hierarchical pore nano-sheet type [email protected] TS-1, which has high stability and high activity. The TS-1 nanosheet is synthesized by adopting tetraethyl orthosilicate TEOS as a silicon source, adopting tetrabutyl titanate TBOT as a titanium source, adopting triethylenediamine derivative quaternary ammonium salt and tetrapropylammonium hydroxide as a composite structure directing agent and constructing a molecular sieve catalyst by a step-by-step hydrothermal method:

1. adding a mixed solution of Tetraethoxysilane (TEOS) and tetrapropylammonium hydroxide into a glass reaction kettle, violently stirring for 30-50min to form transparent sol, hydrolyzing at 65-95 ℃ for 1-2h to form prehydrolyzed silica sol, and dropwise adding quaternary ammonium salt to obtain tetraethoxysilane hydrolysate; wherein the molar ratio range of the ethyl orthosilicate and the tetrapropylammonium hydroxide is as follows: 1:1-5:1, wherein the molar ratio of the ethyl orthosilicate to the quaternary ammonium salt is 4:1-10:1, and the quaternary ammonium salt can be one of alkyl dimethyl hydroxyethyl quaternary ammonium salt, alkyl triethylene diamine derivative and tetrapropenyl ammonium hydroxide quaternary ammonium salt.

2. Dropwise adding a certain amount of tetrabutyl titanate (TBOT)/isopropanol solution into the tetraethoxysilane hydrolysate obtained in the step 1, slowly dropwise adding while stirring, after dropwise adding, heating to 55-85 ℃, further hydrolyzing for 4-6h, and then transferring to a hydrothermal kettle at 180 ℃ for crystallization for 48-96 h to obtain TS-1 nanosheets; wherein the molar ratio range of the ethyl orthosilicate, the tetrabutyl titanate and the isopropanol is as follows: 10:1: 10-20:1: 15;

3. centrifuging, separating and drying the TS-1 nanosheets subjected to the hydrothermal crystallization in the step 2 to obtain nanosheet type TS-1 molecular sieve seed crystals;

4. taking TS-1 molecular sieve seed crystal, transferring the seed crystal to 20 Tetraethoxysilane (TEOS) containing specific content: 14 tetrapropylammonium hydroxide (TPAOH): 9500H₂The mass ratio of the Silicalite-1 prehydrolysis liquid of O (molar ratio) to the TS-1 molecular sieve seed crystal to the hydrolysis liquid is controlled to be 1-2 wt%, and the mixture is transferred to a crystallization kettle at 180 ℃ for crystallization for 24-72 hours;

5. obtaining the titanium silicalite molecular sieve after centrifugal separation, washing and drying;

6. transferring the molecular sieve into a muffle furnace, heating to 550 ℃ at the speed of 2-5 ℃/min, roasting, and keeping the temperature for 5-7 hours to obtain a [email protected] TS-1 molecular sieve;

7. transferring the roasted molecular sieve into a molecular sieve prepared by mixing the following components in parts by weight according to the following formula (100 g): 5-20 g of TPAOH:55mol of H₂Performing secondary crystallization in the solution of O, wherein the hydrothermal temperature of a secondary crystallization kettle is controlled to be 150-170 ℃, and performing continuous hydrothermal crystallization for 12-48 h to obtain a hierarchical pore nano sheet type catalyst [email protected] TS-1 with a hierarchical pore core-shell structure;

8. taking 10g [email protected] TS-1 molecular sieve and massagingRatio of 100SiO₂：25NH₄HF₂：3000H₂And (3) uniformly mixing the O (molar ratio), heating to 50-100 ℃, and stirring for 4-12 hours to obtain the [email protected] TS-1 catalyst.

Compared with the prior art, the invention has the beneficial effects that:

(1) the invention provides a preparation method of an ultrathin nanosheet type core-shell structured [email protected] TS-1 molecular sieve catalyst, which can effectively solve the problem of diffusion confinement in a conventional TS-1 pore channel.

(2) Through secondary pore forming on the [email protected] TS-1 molecular sieve, a pore channel with the pore diameter of 3.8nm can be formed on the [email protected] TS-1 molecular sieve, so that the internal diffusion performance is further improved, and the catalytic activity is improved;

(3) framework titanium species with higher activity can be constructed by activating and post-treating the [email protected] TS-1 molecular sieve, so that the internal diffusion limitation is further eliminated, and the catalytic activity is improved.

Drawings

FIG. 1 shows quaternary ammonium salt templates (I, II, III).

FIG. 2 is a comparison of the results of catalyst application.

FIG. 3 is an HR-TEM image of the [email protected] TS-1 molecular sieve catalyst of example 1. The morphology of the catalyst was observed by a JEM-2010 transmission electron microscope, with an electron beam voltage of 200 kV. In the embodiment 1, the synthetic catalyst is in a thin-layer nanosheet structure, and the thickness of the thin-layer nanosheet layer is 5-10 nm.

FIG. 4 is an HR-TEM image of the conventional TS-1 catalyst of the comparative example. The conventional TS-1 catalyst synthesized in comparative example 1 has an MFI crystal structure with a thickness of 100 nm;

Detailed Description

1. The technical solution of the present invention is further explained by the following embodiments.

Example 1:

mixing 45.0g of tetraethoxysilane (0.2mol, TEOS) with 56.0g of 25 wt.% tetrapropylammonium hydroxide (0.068mol, TPAOH) to form a mixed hydrolysate, stirring for 30min to form a transparent sol, performing prehydrolysis at the normal pressure of 65 ℃ for 1h, adding 4.25g of quaternary ammonium salt Template agent I (0.005mol, Template-I) to obtain tetraethoxysilane, and hydrolyzing the tetraethoxysilaneLiquid; cooling to 0 deg.C, slowly adding 18 wt.% solution containing 4.4g tetrabutyl titanate (0.013mol, TBOT) and 19.8g isopropanol (0.33mol, IPA), heating to 85 deg.C, and hydrolyzing for 4 hr to obtain prehydrolysis sol containing 1SiO₂：0.34TPAOH：1.65IPA：0.065TBT：20H₂O: 0.023 template-I. And after the prehydrolysis is finished, transferring the mixture into a tetrafluoro water hydrothermal kettle at 180 ℃ for hydrothermal crystallization for 48 hours to obtain the TS-1 nanosheet. Cooling to room temperature, centrifugally separating, washing and drying to obtain titanium silicalite molecular sieve seed crystals, and continuously adding 4.16g (0.02mol) of TEOS and 5.69g (0.007mol,25 wt.%) of TPAOH and 85.5g H₂The prehydrolysis liquid of O, the secondary crystallization liquid molar composition is 40TEOS:14 TPAOH: 9500H₂And O, continuously crystallizing at 180 ℃ for 48 hours, and obtaining the titanium-silicon molecular sieve through centrifugal separation, washing and drying. And transferring the molecular sieve into a muffle furnace, and carrying out temperature programming at a speed of 5 ℃/min to 550 ℃ for roasting for 5h to obtain the Silicalite-1/TS-1 molecular sieve. Taking a Silicalite-1/TS-1 molecular sieve, and mixing the molecular sieve with 100g of Silicalite-1/TS-1: 9.90g TPAOH 55mol H₂And transferring the mixture into a tetrafluoro reaction kettle after mixing the O proportion, performing hydrothermal crystallization for 24 hours at the temperature of 170 ℃, and then cooling, filtering, washing and drying to obtain the hierarchical pore nano sheet type catalyst [email protected] TS-1 with the hierarchical pore core-shell structure. Taking 10g of synthesized Silicalite-1/TS-1 molecular sieve, and adding 50g of 1 wt.% NH₄HF₂After the solution is uniformly stirred, the temperature is raised to 60 ℃, 5ml of 30 wt.% hydrogen peroxide solution is dripped, the temperature is kept at 60 ℃ for 4h, the activated [email protected] TS-1 molecular sieve catalyst 1 is obtained, and the molar ratio of Ti/Si of the finished catalyst is 0.24% through ICP analysis.

Example 2:

vigorously stirring a mixed solution of 45.0g of tetraethoxysilane (0.2mol, TEOS) and 56.0g of 25 wt.% tetrapropylammonium hydroxide (0.068mol, TPAOH) for 30min to form a transparent sol, carrying out prehydrolysis at the normal pressure of 85 ℃ for 1h, and then adding 3.78g of quaternary ammonium salt template agent II (0.005mol, template-II) to obtain tetraethoxysilane hydrolysate; cooling to 0 deg.C, slowly adding 18 wt.% solution containing 4.4g tetrabutyl titanate (0.013mol, TBT) and 19.8g isopropanol (0.33mol, IPA), heating to 65 deg.C, hydrolyzing for 4 hr to obtain prehydrolyzed sol with molar ratio of 1SiO₂：0.34TPAOH：1.65IPA：0.065TBT：20H₂O: 0.023 template-II. And after the prehydrolysis is finished, transferring the mixture into a tetrafluoro inner hydrothermal kettle at 180 ℃ for hydrothermal crystallization for 96 hours to obtain the TS-1 nanosheet. Cooling to room temperature, centrifugally separating and washing to obtain titanium-silicon molecular sieve seed crystals, and continuously adding 4.16g (0.02mol) of TEOS and 5.69g (0.007mol,25 wt.%) of TPAOH and 85.5g H₂The mole composition of the prehydrolysis liquid and the secondary crystallization liquid of O is 40TEOS:14 TPAOH: 9500H₂And O, continuously crystallizing at 180 ℃ for 72 hours, and obtaining the titanium-silicon molecular sieve through centrifugal separation, washing and drying. Heating the molecular sieve to 550 ℃ at the speed of 5 ℃/min, roasting for 5h to obtain the molecular sieve with the core-shell structure, taking the [email protected] TS-1 molecular sieve, and mixing the molecular sieve with the mass ratio of 100g Silicalite-1/TS-1: 9.90g TPAOH 55mol H₂And transferring the mixture into a tetrafluoro reaction kettle after mixing the O proportion, performing hydrothermal crystallization for 24 hours at the temperature of 170 ℃, and then cooling, filtering, washing and drying to obtain the hierarchical pore nano sheet type catalyst [email protected] TS-1 with the hierarchical pore core-shell structure. Taking 10g of synthesized [email protected] TS-1 molecular sieve, and adding 100g of 1 wt.% NH₄HF₂After the solution is uniformly stirred, the temperature is raised to 60 ℃, 5ml of 30 wt.% hydrogen peroxide solution is dripped, the temperature is kept at 60 ℃ for 4h, the activated [email protected] TS-1 molecular sieve catalyst 2 is obtained, and the molar ratio of Ti/Si of the finished catalyst is 0.20% through ICP analysis.

Example 3:

vigorously stirring a mixed solution of 45.0g of tetraethoxysilane (0.2mol, TEOS) and 56.0g of 25 wt.% tetrapropylammonium hydroxide (0.068mol, TPAOH) for 30min to form a transparent sol, carrying out prehydrolysis for 1h at the normal pressure and the temperature of 95 ℃, and adding 3.26g of quaternary ammonium salt Template agent III (0.005mol, Template-III) to obtain tetraethoxysilane hydrolysate; cooling to 0 deg.C, slowly adding 18 wt.% solution containing 4.4g tetrabutyl titanate (0.013mol, TBT) and 19.8g isopropanol (0.33mol, IPA), heating to 55 deg.C, and hydrolyzing for 4 hr to obtain prehydrolyzed sol with molar ratio of 1SiO₂:0.325TPAOH:1.56IPA:0.06TBT:20H₂O: 0.023 Template-III. And after the prehydrolysis is finished, transferring the mixture into a tetrafluoro inner hydrothermal kettle at 180 ℃ for hydrothermal crystallization for 48 hours to obtain the TS-1 nanosheet. Cooling to room temperature, centrifugally separating, washing to obtain titanium-silicon molecular sieve seed crystal, and continuously adding 4.16g TEOS (0.02mol) and 5.69g (0.007mol,25 wt.%) TPAOH and 81.24g H₂The mole composition of prehydrolysis liquid and secondary crystallization liquid of O is 40TEOS:14TPAOH：9500H₂And O, continuously crystallizing at 180 ℃ for 72 hours, and obtaining the titanium-silicon molecular sieve through centrifugal separation, washing and drying. Heating the molecular sieve to 550 ℃ at the speed of 5 ℃/min, roasting for 5h to obtain the molecular sieve with the core-shell structure, taking the [email protected] TS-1 molecular sieve, and mixing the molecular sieve with the mass ratio of 100g Silicalite-1/TS-1: 9.90g TPAOH 55mol H₂And mixing the mixture with the proportion of O, transferring the mixture into a tetrafluoro reaction kettle, performing hydrothermal crystallization for 12 hours at the temperature of 150 ℃, and then cooling, filtering, washing and drying to obtain the hierarchical pore [email protected] TS-1. Taking 10g of synthesized Silicalite-1/TS-1 molecular sieve, and adding 100g of 1 wt.% NH₄And (3) uniformly stirring the solution F, heating to 60 ℃, then dropwise adding 5ml of 30 wt.% hydrogen peroxide solution, keeping the temperature at 60 ℃ for 4 hours to obtain an activated [email protected] TS-1 molecular sieve catalyst 3, and obtaining a catalyst finished product with a Ti/Si molar ratio of 0.28% through ICP analysis.

Comparative example 1

Uniformly mixing 45.0g of tetraethyl orthosilicate (0.2mol) and 56.0g of 25 wt.% tetrapropylammonium hydroxide (0.068mol), and pre-hydrolyzing at the normal pressure and the temperature of 65 ℃ for 1h to obtain an ethyl orthosilicate hydrolysate; continuously dropwise adding 0.0033mol of 10 wt.% isopropanol solution of tetrabutyl titanate, heating to 85 ℃, continuously hydrolyzing for 4h, wherein the mol ratio of the prehydrolysis sol is 1SiO₂/0.325TPAOH/1.56IPA/0.06TBT/20H₂And O. And after the prehydrolysis is finished, transferring the mixture into a tetrafluoro inner hydrothermal kettle at 180 ℃ for hydrothermal crystallization for 2-6 days to obtain the TS-1 molecular sieve. Cooling to room temperature, centrifugally separating, washing, raising the temperature to 550 ℃ at a speed of 5 ℃/min, and roasting for 5h to obtain the conventional titanium silicalite TS-1 catalyst 4.

Catalyst evaluation

The catalyst evaluation is carried out at 42-45 ℃, and the catalyst evaluation conditions are as follows: n (methanol), n (chloropropene), n (hydrogen peroxide) in a molar ratio of 2.2:2:1, 4g/mol of Hydrogen Peroxide (HP) in the amount of TS-1, keeping the reaction temperature at 15-18 ℃, uniformly dropwise adding hydrogen peroxide for 120min, keeping the temperature at 15-18 ℃, continuously reacting for 1.5h, analyzing the conversion rate of chloropropene and the selectivity of epichlorohydrin, dichloropropanol and condensed ether by Agilent GC8890 gas chromatography, wherein the chromatographic detection conditions are as follows: the vaporization temperature is 250 ℃, the temperature of the column box is 220 ℃, the flow rate of the carrier gas is 0.8ml/min, and the FID temperature is 300 ℃. The product composition was analyzed using acetonitrile as solvent and n-butanol as internal standard.

Performance index of the catalyst:

yield of epichlorohydrin-100% moles of epichlorohydrin produced/moles of hydrogen peroxide converted

Selectivity% of epichlorohydrin (yield of epichlorohydrin/(yield of epichlorohydrin + yield of dichloropropanol + yield of condensed ether) × 100%

Detecting the residual hydrogen peroxide by an iodometry method: the method comprises the steps of taking 0.5g of reaction liquid, adding 1g of potassium iodide, keeping out of the sun for 5 minutes, then adding 1g of ammonium molybdate, and then titrating with sodium thiosulfate. And (3) when the titration is carried out until the color of the solution changes, adding a starch indicator, and when the color of the solution is transparent, determining the end point of the titration.

Table 1: comparison of catalyst evaluation results