CN101555236B - Nano-SiO2 or zeolite molecular sieve material catalyzed olefin and H2O2 liquid-phase high-selectivity epoxidation method - Google Patents

Abstract

The present invention relates to a chemical reaction process for preparing epoxides through heterogeneous catalytic oxidation without using any catalyst containing transition metals, specifically a kind of nano- _SiO2 or zeolite molecular sieve material catalyzed olefin and _{H2O 2} Liquid-phase high-selectivity epoxidation method, using nano- _SiO2 materials, or surface-modified activated _SiO2 materials with organic functional groups, or zeolite molecular sieves directly as reaction catalysts, and reaction substrates and solvents to form " SiO ₂ -alkene-solvent-H ₂ O ₂ /H ₂ O" heterogeneous catalytic epoxidation reaction system catalyzes a wide range of olefin epoxidation reactions, and the epoxidation oxidation reagent is commercially available H ₂ O ₂ , the reaction temperature The temperature is controlled at 0-100°C, and the reaction time is 0.5-24h. The advantages of the present invention are: no catalyst containing transition metals is used, the conversion rate of raw materials is high, the selectivity of the target product is good, the reaction time is short, the efficiency is high, the reaction conditions are mild, the operation is easy to control, the cost is low, and the whole process environment friendly.

Description

Nano-SiO2 or zeolite molecular sieve material catalyzed olefin and H2O2 liquid-phase high-selectivity epoxidation method

technical field

The present invention relates to a chemical reaction process for the preparation of epoxides through heterogeneous catalytic oxidation using only inorganic catalysts without using any catalysts containing transition metals, specifically a nano _-SiO2 material catalyzed olefin with 30% _{H2O 2} Liquid phase highly selective epoxidation method.

Background technique

Olefin epoxidation products are a class of organic raw materials and intermediates with a wide range of uses, and are widely used in petrochemical, fine chemical and organic synthesis fields. However, in addition to ethylene oxide, the production methods of most epoxy compounds such as propylene oxide and styrene oxide in the industry are still the traditional halohydrin method and Haakon method (also known as indirect oxidation method) which are harmful to the environment. Law).

Highly selective oxidation of hydrocarbons is one of the most important tasks in the 21st century [(a) CL Hill, Nature 1999, 401, 436; (b) DEde Vos; BFSels; PA Jacobs, Adv.Catal.2001, 46, 1 ], the catalyzed epoxidation reaction of olefin compounds under mild conditions has always been the focus of research in the field of fine chemicals. For the catalytic epoxidation of olefinic compounds, the homogeneous catalytic process has its obvious disadvantage, which is that the separation, recovery and recycling of the catalyst are very difficult. Scientists have been working hard to design and prepare suitable heterogeneous catalysts, because such catalytic systems can easily overcome the typical difficulties encountered in homogeneous systems [ZWXi et al., Science 2001, 292, 1139]. Heterogeneous catalysts play an important role in chemical and fine chemical processes due to their easy separation from the reaction system. As we all know, the smaller the particle size of heterogeneous catalysts, the higher their catalytic activity. Due to the large specific surface area of nanoscale catalysts, a large number of active sites are exposed on the surface, so that the reactant molecules can be close to the active sites of the catalyst. Sufficient contact at the "molecular level" shows a catalytic activity far superior to that of the corresponding bulk material, and there are many related reports. The catalytic epoxidation technology developed in recent years, using 30% H ₂ O ₂ as the oxidant is very common, because it is relatively cheap and easy to obtain as an oxidant, and the content of active oxygen is high, and the by-product after the reaction is only water , good environmental protection, but low oxidation activity, need to add high-performance catalyst [K. Jahnisch, V. Hessel, H. Lowe, M. Baerns, Angew. Chem. Int. Ed. 2004, 43, 406]. For example, Chinese patent CN1172922CGO discloses a method for epoxidation of olefins with hydrogen peroxide in the presence of a titanium-containing molecular sieve catalyst and a salt, and Chinese patent CN1330642C discloses an epoxidation method in the presence of a zeolite-based catalyst and a solvent , A method for preparing epoxides by reacting olefins with peroxides. In addition, it is reported that phosphotungstic heteropolyacid catalysts can effectively catalyze the epoxidation of propylene and _H2O2 to epoxycyclopropane through reaction control under phase transfer conditions; _{SiO2 supported} metal Schiff-base complexes can effectively catalyze ethylene Epoxidation to generate 1,2-oxirane; use cis-MoO ₂ (L)(solv)[L=salicyl salicylhydrazide] and Y molecular sieve to form a composite catalyst to epoxidize styrene under mild conditions; vanadium Schiff-base complexes can effectively catalyze the epoxidation of styrene and cyclohexene with _H2O2 oxidants [(a) SNRao, KNMunshi, NNRao, J.Mol.Catal.A:Chem.2000, 156 _, 205; (b) DM Boghaei; S. Mohebi, J. Mol. Catal. A: Chem. 2002, 179, 41; (c) T. Punniyamurthy; S. Velusamy; ]. However, in order to obtain high catalytic activity in these traditional systems, the reagents used for epoxidation of olefins mainly include peroxyacid, tert-butanol peroxy, hypochlorite, iodosobenzene, additive + H ₂ O ₂ etc. as an oxidizing agent.

对较大分子的反应催化活性差)，导致了相关技术在精细化工领域的应用受到限制，以致于难以工业化。Using titanium-silicon molecular sieve catalysts, industrial H ₂ O ₂ with a mass fraction of 30% can be used as an oxidant, which is environmentally friendly, so the appearance and application of titanium-containing zeolite catalyst TS-1 was known as the heterogeneous process of traditional homogeneous processes at that time. milestone; so far the catalyst system has been extended to TS-1, Ti-β, Ti-MWW, Ti-MCM-41, Ti-MCM-48, Ti-SBA-15, implanted Ti-SiO ₂ , etc., domestic Guo News, Wu Peng, Li Can, Xia Qinghua, etc. are all involved in this kind of research [(a) B.Notari, Adv.Catal.1996, 41, 23; (b) QHXia, X.Chen, T.Tatsumi, J.Mol .Catal.A: Chem.2001, 176, 179; (c) P.Wu, T.Tatsumi, Chem.Commun.2001, 1714; (d) XWGuo, XSWang, Catal.Today 2002, 74, 65; (e ) QHYang, Can Li, J. Catal. 1999, 183, 128.]. The catalytic activity of this catalytic system can be compared to the most excellent homogeneous complexes and simulated enzyme catalytic systems; and its advantages are also particularly obvious, because these heterogeneous catalysts can be recovered by multiple filtration and recycled, And 30% H ₂ O ₂ can be used as the oxidizing agent, the oxidation efficiency is high, the by-products are few, the pollution-free and corrosion-free and meet the requirements of green environmental protection, and have high application value. However, for large-scale processes in the chemical industry, the synthesis cost of titanium-containing zeolites is still relatively high, and zeolite molecular sieves with different pore sizes have significant shape selectivity for substrate molecules (for example, TS-1 molecular sieves have a pore size of about

The reaction catalytic activity to larger molecules is poor), which has led to the limitation of the application of related technologies in the field of fine chemicals, so that it is difficult to industrialize.

The catalytic activities of the above-mentioned epoxidation catalytic systems are all relatively high, but they all involve transition metal complexes or porous synthetic material active centers containing metal Ti, Mg, Al, and the preparation cost of the catalyst is relatively high, and recycling is difficult and easy. Inactivation, easy to cause environmental pollution, and there is not much difference in the interpretation of the catalytic mechanism: that is, transition metal ions interact with H ₂ O ₂ to form active intermediates. Silica, as an inert catalyst carrier and a framework component of molecular sieves, is widely used in the preparation of heterogeneous catalysts and the synthesis of porous zeolite molecular sieve materials, but no research has mentioned silica and other porous silicon-based materials without transition metals. The material has catalytic oxidation activity. Now, we found for the first time that in the heterogeneous catalytic reaction system composed of "SiO ₂ -alkene-solvent-H ₂ O ₂ /H ₂ O", nano-SiO ₂ materials without transition metals (via SEM-EDX, ICP, The addition of AAS analysis without transition metal) plays a key role in significantly improving the substrate conversion rate and epoxidation selectivity. Preliminary results show that it has a good effect on functionalized olefins, cycloolefins and linear olefins, and can well overcome traditional zeolites. The limitation of material pore size shape selectivity, and repeated centrifugation, washing, drying, and recycling, and the substrate conversion rate and epoxidation selectivity can be maintained. This is an amazing and interesting discovery , the system is simple and cheap, and conforms to the current development trend of catalytic technology.

Contents of the invention

The present invention proposes a method for epoxidizing olefins in order to overcome the main shortcomings commonly found in the above-mentioned epoxidation systems, that is, a method for highly selective epoxidation of olefins and H ₂ O ₂ in liquid phase catalyzed by nano-SiO ₂ materials.

Nano-SiO ₂ or zeolite molecular sieve catalyzed olefin and H ₂ O ₂ liquid-phase high-selectivity epoxidation method, it is the nano-SiO ₂ material, or activated SiO ₂ material with organic functional groups after surface modification , or zeolite molecular sieve directly as the catalyst of the reaction, and the reaction substrate olefin and solvent to form "SiO ₂ - olefin - solvent - H ₂ O ₂ /H ₂ O" heterogeneous catalytic epoxidation reaction system to catalyze olefin epoxidation reaction , the oxidant used for epoxidation is H ₂ O ₂ , the reaction temperature is controlled at 60°C, and the reaction time is 0.5 to 24 hours. The olefins are styrene, cyclohexene, cyclooctene, norbornene, α-pinene , β-pinene, cinnamyl chloride, methyl acrylate, ethyl acrylate, butyl acrylate, allyl alcohol, acrylonitrile, 1-octene and other olefins.

The method includes:

(1) Liquid-phase highly selective epoxidation method of olefins and H ₂ O ₂ catalyzed by SiO ₂ with different particle sizes;

(2) Highly selective epoxidation method of olefins and H ₂ O ₂ in liquid phase catalyzed by SiO ₂ with different sources, different specific surface areas, and different particle sizes;

(3) The surface of various _SiO2 powder materials is properly modified by different silicates with organic functional groups or other silylating agents, and a series of activated _SiO2 materials with silane functional groups on the surface are prepared. Highly selective epoxidation method of olefins and H ₂ O ₂ in liquid phase;

(4) A method for highly selective epoxidation of olefins and H ₂ O ₂ in liquid phase catalyzed by various low-cost prepared zeolite molecular sieve materials with different specific surface areas and different pore sizes.

Detailed description of the invention

In the method of the present invention, _the liquid-phase selective epoxidation reaction of olefins catalyzed by the nanometer _SiO2 material and _H2O2 forms corresponding highly selective epoxidation products. After a series of catalytic reactions and related characterization studies, the mechanism of epoxidation of olefin compounds and H ₂ O ₂ catalyzed by SiO ₂ materials can be summarized as: Surface Adsorption assisted biMolecular Epoxidation (SAME) ), that is, the surface of these silicon-based materials with a relatively high specific surface area (usually greater than 200m ² /g) has amphiphilicity (hydrophilic-lipophilic), which can simultaneously combine the olefin substrate molecules in the organic phase and the aqueous phase The active oxidant molecules in the adsorbed together overcome the interfacial tension and allow the epoxidation reaction to occur.

The _SiO2 material of the high specific surface area that the present invention uses, nanometer particle size can obtain from the following several ways: (1) aerosil-200, aerosil-300 etc. of different specifications such as foreign professional companies such as Aldrich, Degussa, Alfa that directly buy Commodities, the specific surface area of these materials is between 200-350m ² /g, and the particle size is between 10-20nm; (2) Directly purchase similar products from domestic manufacturers, commonly known as white carbon black or fumed silica (obtained by high-temperature incineration of organic silicon) ), usually used as a raw material for hydrothermal synthesis of high-purity heteroatom zeolite molecular sieves; (3) the laboratory uses ultrasonic, high-speed shearing, and microemulsification environmental hydrolysis technology to start from organic silicon, through low-temperature hydrolysis, spray drying, roasting Self-made nano-SiO ₂ material (particle size is less than 20nm); (4) surface-modified SiO ₂ material: use the following silicates or other silylating agents with organic functional groups (with (EtO) ₃ Si-C ₃ H ₆ NH ₂ , (MeO) ₃ Si-C ₃ H ₆ NH ₂ , CH ₃ (EtO) ₂ Si-C ₃ H ₆ NH ₂ , (EtO) ₃ Si-(CH ₂ ) ₃ -NHC ₂ H ₄ NH _2. CH ₃ Si (OCH ₃ ) ₃ , (CH ₃ ) ₃ Si-Cl, HMDS, CH ₃ (MeO) ₂ Si-C ₃ H ₆ NHC ₂ H ₄ NH ₂ etc.) directly react with powder nano-SiO ₂ material So that the surface can be properly modified to prepare a series of activated _SiO2 materials with organic functional groups on the surface; (5) molecular sieve materials with different specific surface areas and different pore sizes prepared by simple methods at low cost, such as 4A, ZSM -5. Mordenite, beta, SBA-15 series, Y, MCM-41 series, MCM-22, SAPOs series, AlPOs series and other materials; (6) Various silica gel materials, such as silica gel for chromatography, dehydration and drying Silica gel, etc. (100-300 mesh).

In the method of the present invention, the reaction solvents used to catalyze the liquid-phase selective epoxidation reaction of olefins and _H2O2 are common solvents, the price is low, and _the reaction conditions are easy to control. The solvent is one of the following: CH ₃ OH, EtOH, ^But OH, MeCOMe, MeCOEt, cyclohexanone, CH ₃ CN, DMF, DMA, CHCl ₃ , CH ₂ Cl ₂ , DMSO, cyclohexane, THF, Ether wait. In addition, commonly used and inexpensive various salts are commonly used as additives for the epoxidation reaction system in combination with the reaction solvent, and a salt solution with a concentration range of 0.01-1mol/L in the aqueous solution is prepared to work together with the reaction solvent to provide a more Suitable reaction medium for olefin epoxidation. The salt is one of the following: K ₂ CO ₃ , Na ₂ CO ₃ , KHCO ₃ , NaHCO ₃ , CH3COONa, CH ₃ COOK, NaH ₂ PO ₄ , Na ₂ HPO ₄ , Na ₃ PO ₄ , potassium tartrate, potassium tartrate , sodium tartrate, slightly soluble CaSO ₄ and MgSO ₄ and other single alkali metal/alkaline earth metal or mixed salts.

The molar ratio of H ₂ O ₂ to olefin is 0.5-5.

The volume ratio of the solvent and the aqueous salt solution is 3˜1/3.

The catalyst zeolite molecular screening is one of 4A, ZSM-5, mordenite, beta, SBA-15 series, Y, MCM-41 series, MCM-22, SAPOs series and AlPOs.

Described reaction temperature is 0～80 ℃

The reaction time is 0.5-6h.

In the method of the present invention, the reaction process is very simple and easy, and can efficiently catalyze the highly selective epoxidation of various olefins, and the olefins are suitable for linear or branched terminal olefins, internal olefins, and cyclic internal olefins. As well as olefins with functional groups, the invention patent mainly selects olefins such as styrenes, cycloolefins, acrylates, ketenes, and linear olefins.

The present invention has the following advantages:

(1) No transition metal catalysts are used. The present invention only uses the nanometer _SiO2 material of commercialization or self-made by simple method, or through the activated _SiO2 material of organic functional group through surface modification, or the common zeolite molecular sieve of low cost directly as the catalyzer of reaction, can bring remarkable effect, avoiding the hydrothermal synthesis and post-treatment process of high-cost Ti-Si zeolite and hydrotalcite catalysts, avoiding the tedious organic synthesis and purification of organic complex catalysts, and avoiding the waste and pollution of transition metal resources. These SiO ₂ materials can be used to catalyze the epoxidation reaction of olefin after simple post-treatment and activation after the reaction, which has good recyclability and greatly saves cost.

(2) The conversion rate of the raw material is high, and the selectivity of the target product is good. The conversion rate of raw materials in the prior art is generally about 60-80%, and there are incomplete conversion and other by-products, which bring difficulties to the separation. When the present invention catalyzes and oxidizes various types of olefins to generate epoxides under mild conditions, the conversion rate of raw materials is high, and even can be completely converted, and the product is only the target epoxidation product without other by-products, and the selectivity of the reaction is good. , high yield.

(3) The reaction time is short and the efficiency is high. Under the conditions of the present invention, the reaction time for catalytic oxidation of functionalized olefins to generate epoxides is 0.5 to 24 hours, and the preferred reaction time is 0.5 to 6 hours. Compared with other methods for preparing epoxides by catalytic oxidation, the reaction time is short , the advantage of high reaction efficiency.

(4) The reaction conditions are mild and the operation is easy to control. The reaction of the present invention is carried out in an organic solvent, and the reaction temperature is controlled at 0-100°C. Temperature is an important factor affecting the reaction time and selectivity. In this catalytic oxidation system, every time the temperature increases by 10°C, the reaction rate increases by 0.5-100°C. 2 times, but if the temperature is too high, it will increase the energy consumption, and it will also cause the selectivity of the target product to deteriorate, complicate the product distribution, and increase the by-products, so it is necessary to choose a suitable temperature.

(5) Low cost. The prior art mainly adopts sodium hypochlorite, peroxyacid and alkyl hydroperoxide as oxidant, and the production cost is higher; in the process of reaction, the by-products they generate will cause certain harm and pollution to the environment; and they are relatively It is unstable, easy to decompose, and has disadvantages such as unsafe transportation, storage and use. The epoxidation oxidation reagent used in the present invention is commercially available 30% H ₂ O ₂ , and the raw material is cheap and easy to obtain. Compared with a series of organic peroxides or sodium hypochlorite as epoxidation reagents, it has the advantages of safe use, convenient transportation and storage. The epoxidation method provided by the invention does not require special equipment when preparing epoxides, has the characteristics of mild reaction conditions, convenient operation and relatively low cost, and has good industrial application prospects.

(6) The whole process is environmentally friendly, and the organic solvent after the reaction can be recovered and reused by distillation, which is a green chemical synthesis method. The raw materials consumed by the method are only olefins and H ₂ O ₂ , the product is a single epoxide, the process is simple, and the oxidant consumption is very low, and it is a new way suitable for large-scale industrial production.

Detailed ways

The technical solution of the present invention will be further described below through several specific examples. The following examples are not intended to limit the present invention.

Example 1:

In a 25ml round bottom flask, add 5ml of solvent acetonitrile, 5ml of 0.2mol/L K ₂ CO ₃ aqueous solution, 20mg of nano-SiO ₂ , 0.21g of styrene (2.0mmol), 0.34g of H ₂ O ₂ (3.0mmol, 30 % aqueous solution, n hydrogen peroxide: n styrene = 1.5:1), and then the reactor was heated to 60°C under rapid magnetic stirring for 6 hours (round bottom flask equipped with a condenser tube), and SiO ₂ was recovered after extraction, washed, and vacuum-dried . The solution was quantitatively analyzed by chromatography. The conversion rate of styrene is 95.0 mol%, and the selectivity of epoxide is 99.8%.

Example 2:

In a 50ml round bottom flask, add 10ml of solvent tert-butanol, 10ml of 0.1mol/L NaHCO ₃ aqueous solution, 50mg of nano-SiO ₂ , 1.36g of norbornene (10mmol), 1.36g of H ₂ O ₂ (12mmol, 30 % aqueous solution, n hydrogen peroxide: n styrene = 1.2:1), then the reactor was heated to 60°C under rapid magnetic stirring to react for 6h (round-bottomed flask equipped with a condenser tube), recovered SiO ₂ after centrifugation, washed, and vacuum-dried . The solution was quantitatively analyzed by chromatography. The norbornene conversion rate was 97.2 mol%, and the epoxide selectivity was 100%.

Example 3

In a 500ml round bottom flask, add 100ml of solvent methanol, 100ml of 0.2mol/L Na ₃ PO ₄ aqueous solution, 100mg of nano-SiO ₂ , 11.0g of cyclooctene (100mmol), 17.0g of H ₂ O ₂ (150mmol, 30 % aqueous solution, n hydrogen peroxide: n styrene = 1.5:1), and then the reactor was heated up to 60°C under rapid magnetic stirring for 6 hours of reaction (round-bottomed flask equipped with a condenser), recovered SiO ₂ after filtration, washed, and vacuum-dried . The solution was quantitatively analyzed by chromatography. The cyclooctene conversion rate was 95.3 mol%, and the epoxide selectivity was 100%.

Example 4

In a 100ml round bottom flask, add 20ml of solvent acetonitrile, 20ml of 0.2mol/L CH ₃ COOK aqueous solution, 150mg of ZSM-5 (SiO ₂ /Al ₂ O ₃ =25), 1.04g of styrene (10mmol), 1.36 g H ₂ O ₂ (12mmol, 30% aqueous solution, n hydrogen peroxide: n styrene = 1.2:1), then the reactor was heated to 60°C for 6h under rapid magnetic stirring (round-bottomed flask equipped with a condenser tube), centrifuged Afterwards, ZSM-5 was recovered, washed, and vacuum-dried. The solution was quantitatively analyzed by chromatography. The conversion rate of styrene is 92.5 mol%, and the selectivity of epoxide is 99.6%.

Example 5

In a 100ml round bottom flask, add 20ml of solvent acetonitrile, 20ml of 0.2mol/L MgSO ₄ aqueous solution, 150mg of SBA-15, 1.10g of cyclooctene (10mmol), 1.36g of H ₂ O ₂ (12mmol, 30% aqueous solution , n hydrogen peroxide: n styrene = 1.2:1), then the reactor was heated to 60°C for 6h under rapid magnetic stirring (round-bottomed flask equipped with a condenser tube), and SBA-15 was recovered after centrifugation, washed, and vacuum-dried. The solution was quantitatively analyzed by chromatography. The cyclooctene conversion rate was 98.3 mol%, and the epoxide selectivity was 100%.

Embodiment 6-22

Representative examples are provided below in the form of tables, and the catalyst is preferably commercialized or self-made nano- _SiO2 material by simple method, or activated _SiO2 material with organic functional groups through surface modification, or low-cost common zeolite Molecular sieves, preferably styrene, cyclohexene, cyclooctene, norbornene, α-pinene, β-pinene, cinnamyl chloride, methyl acrylate, ethyl acrylate, butyl acrylate, propenyl alcohol, acrylonitrile , 1-octene and other alkenes. Example 6 is a blank reaction experiment example, that is, no catalyst SiO ₂ is added, and its experimental method and steps follow Example 1-5; the experimental method and steps of Example 7-22 also follow Example 1-5, 100mg SiO ₂ or Zeolite molecular sieve, 50ml solvent acetonitrile, 50ml salt solution (concentration range is 0.05～1mol/L), these result examples do not constitute limitation to the present invention.

Show by above-mentioned result example, according to the reaction conditions provided by the present invention, can selectively oxidize a wide range of substrates to epoxides, the method has mild reaction conditions, easy to control operation, high conversion rate of raw materials, target product The selectivity is good, the reaction time is short, the efficiency is high, the cost is low, and the whole process is environmentally friendly and green, so it has a good application prospect.

Claims (6)

1. A nano-SiO ₂ or zeolite molecular sieve material catalyzes olefins and H ₂ O ₂ liquid-phase high-selectivity epoxidation method, which uses nano-SiO ₂ , or ZSM-5 or SBA-15 directly as the catalyst for the reaction, the catalyst Form SiO ₂ -alkene-solvent-H ₂ O ₂ /H ₂ O heterogeneous catalytic epoxidation reaction system with reaction substrate olefin and solvent to catalyze olefin epoxidation reaction, and the oxidant used for epoxidation is H ₂ O ₂ , the reaction temperature is controlled at 60°C, the reaction time is 0.5-24h, and the olefins are styrene, cyclohexene, cyclooctene, norbornene, α-pinene, β-pinene, cinnamyl chloride, methyl acrylate ester, ethyl acrylate, butyl acrylate, propenyl alcohol, acrylonitrile, 1-octene olefin; the solvent is methanol, ethanol, tert-butanol, acetone, butanone, cyclohexanone, acetonitrile, N , one of N'-dimethylformamide, N,N'-dimethylacetamide, chloroform, dichloromethane, dimethyl sulfoxide, cyclohexane, tetrahydrofuran, ether. 2. as claimed in claim 1, nanometer _SiO2 or zeolite molecular sieve material catalyzes olefins and _H2O2 liquid phase high selectivity epoxidation method, it is characterized in that: cooperate with reaction solvent in reaction system as epoxidation _reaction The system is also added with salt additives, among which the additives are K ₂ CO ₃ , Na ₂ CO ₃ , KHCO ₃ , NaHCO ₃ , CH ₃ COONa, CH ₃ COOK, NaH ₂ PO ₄ , Na ₂ HPO ₄ , Na ₃ PO ₄ , Potassium tartrate, sodium tartrate, single alkali metal or alkaline earth metal or mixed salts in slightly soluble CaSO ₄ and MgSO ₄ . 3. The nano-SiO ₂ or zeolite molecular sieve material catalyzed liquid-phase high-selectivity epoxidation method of olefins and H ₂ O ₂ as claimed in claim 1, characterized in that: the reaction time is 0.5-6 hours. 4. as claimed in claim 2, nanometer _SiO2 or zeolite molecular sieve material catalyzes olefins and _H2O2 liquid phase high selectivity epoxidation method, it is characterized in that: described salt additive is _the aqueous solution of salt, the concentration range of aqueous solution 0.01~1mol/L. 5. Nano SiO ₂ or zeolite molecular sieve material catalyzed olefin and H ₂ O ₂ liquid phase high selectivity epoxidation method as claimed in claim 1, it is characterized in that: the molar ratio of described H ₂ O ₂ and olefin is 0.5～ 5. 6. as claimed in claim 4, nano- _SiO2 or zeolite molecular sieve material catalyzes olefins and _H2O2 Liquid phase high selectivity epoxidation method, it is characterized in that: the volume ratio of _the aqueous solution of described solvent and salt is: 3～ 1/3.