CN103586069B - For the preparation method of catalyzer and the method for epoxidation of olefins of epoxidation reaction of olefines - Google Patents

Abstract

The present invention provides the preparation method of a kind of catalyzer for epoxidation reaction of olefines, comprise the mixture of preparation containing HTS, binding agent source, alkaline earth metal oxide and water, this mixture forming is obtained formed body, and by dry for described formed body also roasting; Described binding agent source is be selected from by silicon sol, the silane with at least two hydrolysable group and at least one that has in the siloxanes of at least two hydrolysable group; In described mixture, HTS, with SiO₂The weight ratio of binding agent source, alkaline earth metal oxide and the water counted is (70-98): (1.5-40): (0.05-25): (5-50). Present invention also offers a kind of method of epoxidation of olefins. The catalyzer adopting the method for the present invention to prepare demonstrates high hydrogen peroxide conversion and epoxide selectivity in epoxidation reaction of olefines.

Description

Method for preparing catalyst for olefin epoxidation and method for epoxidizing olefin

This application is a divisional application of a Chinese patent application with an application date of October 11, 2010, an application number of 201010511564.3, and an invention title of "Olefin Epoxidation Catalyst and Its Preparation Method and Olefin Epoxidation Method".

technical field

The invention relates to an olefin epoxidation catalyst, a preparation method thereof and a method for epoxidizing olefin using the catalyst.

Background technique

With the development of petrochemical and fine chemical industry, oxygen-containing organic compounds have become very important intermediates. Using hydrogen peroxide as oxidant and titanium-silicon molecular sieve as catalyst to catalyze the epoxidation of olefins to prepare oxygen-containing organic compounds meets the requirements of green chemistry and atomic economy development concepts, and is a green new process with great development prospects.

Epoxides are usually prepared by epoxidizing alkenes with hydrogen peroxide in the presence of a catalyst. At present, titanium silicate molecular sieves are the most commonly used catalysts in olefin epoxidation reactions. However, when using a fixed-bed reaction process, the catalyst containing titanium-silicon molecular sieve must be shaped and have sufficient crushing strength, otherwise the catalyst is easily broken to form fine particles or powder during use, and the broken catalyst will cause the catalyst bed on the one hand. The increase in layer pressure drop will increase the cost of production and operation and increase the risk of production; on the other hand, if the broken catalyst is carried out by the reaction product, it will lead to the loss of catalyst and the complexity of product separation.

Moreover, the chemical properties of epoxides are active, and it is easy to further open the ring in the reaction system to cause side reactions, resulting in a decrease in the selectivity of epoxides.

CN1140348C discloses a composite titanium-silicon catalyst made by the reaction of silicon source, titanium source, template agent, alkali, distilled water and inorganic oxide, wherein, the catalyst is made of 1.0-80.0% by weight of MFI structure titanium-silicon molecular sieve and 20.0 - 99.0% by weight of inorganic oxides with a particle size of 0.1-20mm composed of spherical or irregular particles. The inorganic oxide is selected from TiO ₂ , SiO ₂ , ZrO ₂ , Al ₂ O ₃ , Na ₂ O, CaO, K ₂ O, PbO or their composites or mixtures, and the inorganic oxide is spherical or irregular grainy. The patent also discloses a method for preparing the above catalyst, which method includes introducing an inorganic oxide into silicon source: titanium source: templating agent: alkali: distilled water in a molar ratio of 1:0.001-0.2:0.03-0.5:0.1-5: In the hydrothermal synthesis system of the MFI structure titanium-silicon molecular sieve composed of 10-200, it can be aged at 0-100°C for 1-5 days at a low temperature before normal crystallization, so that the MFI structure titanium-silicon molecular sieve can precipitate crystal nuclei on the surface of the inorganic oxide and in-situ growth, and then normal crystallization at 120-200°C for 1-10 days, then the composite material is separated from the mother liquor, dried, and roasted; the prepared composite catalyst is then in-situ shaped for 1-5 times. The patent further discloses that the catalyst can be used in the epoxidation of propylene with hydrogen peroxide as the oxidant. But, the inorganic oxide in the catalyst that this patent embodiment discloses is the mixture of silicon dioxide or silicon dioxide and aluminum oxide; In the propylene epoxidation reaction using hydrogen peroxide as the oxidant, the conversion rate of hydrogen peroxide (91.4-94.8%) and the selectivity of propylene oxide (80.8-89.2%) need to be further improved.

CN101203306A discloses a kind of epoxidation catalyst, and this catalyst comprises titanium zeolite or vanadium zeolite, binding agent and zinc oxide, and described catalyst is by preparing the aqueous mixture of described zeolite, binding agent source and zinc oxide source and make described The mixture is produced by rapid drying. Although the application discloses that the rate of ring opening of propylene oxide is significantly reduced for catalysts incorporating zinc during spray drying compared to catalysts containing no zinc, the rate of ring opening of catalysts incorporating zinc after particle formation by spray drying The ring rate is much higher than that of the zinc-free catalyst. Therefore, the preparation method of the catalyst according to this application has a very high dependence on the processing sequence; moreover, the application does not specifically disclose the conversion of hydrogen peroxide and the selectivity of propylene oxide during the epoxidation process.

CN1418876A discloses a kind of olefin epoxidation catalyst, by weight percentage, this catalyst comprises following components: 10-50% alumina carrier; 40-80% titanium silicon molecular sieve, the general formula of titanium silicon molecular sieve is xTiO ₂ · (1-x) SiO ₂ , x=0.0005-0.04, where x is the molar ratio, x=Ti/(Si+Ti); 5-40% alkali metal or alkaline earth metal oxides and mixtures thereof. Although the catalyst of this application is used for the propylene epoxidation reaction with hydrogen peroxide as the oxidant, higher propylene oxide selectivity can be obtained, but the conversion rate of hydrogen peroxide is low, only 85.1-93.5%.

Therefore, there is still a need for a catalyst that not only has sufficient hardness and wear resistance, but also has high catalytic activity, and can also enable the epoxidation reaction using the catalyst to have high epoxidation product selectivity and Hydrogen peroxide conversion.

Contents of the invention

The object of the present invention is to provide a kind of olefin epoxidation catalyst and preparation method thereof, this olefin epoxidation catalyst has high crushing strength and shows higher epoxide selectivity and overshoot in olefin epoxidation reaction Hydrogen peroxide conversion rate; The object of the present invention is also to provide a method for epoxidizing olefins, which has higher selectivity of epoxidized products and hydrogen peroxide conversion rate.

The invention provides an olefin epoxidation catalyst, wherein the catalyst contains a titanium-silicon molecular sieve, a binder and an alkaline earth metal oxide, and the binder is amorphous silicon dioxide.

The present invention also provides a method for preparing the olefin epoxidation catalyst, wherein the method comprises: preparing a mixture containing titanium-silicon molecular sieve, binder source, alkaline earth metal oxide and water, and forming the mixture A molded body is obtained, and the molded body is dried and calcined; the binder source is selected from silica sol, silane with at least two hydrolyzable groups, and siloxane with at least two hydrolyzable groups At least one of them; in the mixture, the weight ratio of titanium silicon molecular sieve, binder source calculated as _SiO2 , alkaline earth metal oxide and water is (70-98): (1.5-40): (0.05- 25): (5-50).

The present invention also provides a method for epoxidizing olefins, the method comprising contacting olefins with hydrogen peroxide in a solvent in the presence of a catalyst, wherein the catalyst is the catalyst provided by the present invention.

Although the catalyst disclosed by CN1418876A is used for epoxidation reaction, the selectivity of propylene oxide can reach more than 95%, but it should be noted that the concentration of hydrogen peroxide in the epoxidation reaction conditions adopted in the embodiment of comparative document 1 Low, only 0.78 mol/L. That is to say, the high propylene oxide selectivity shown by the catalyst disclosed in CN1418876A in the propylene epoxidation reaction conditions is based on the use of low-concentration hydrogen peroxide, if the concentration of hydrogen peroxide is further increased , The catalyst disclosed in CN1418876A is difficult to show high catalytic activity in propylene epoxidation reaction, that is, high propylene oxide selectivity and hydrogen peroxide conversion rate. The inventors of the present invention have found through research that this may be due to the strong acidity of alumina, which leads to the solvolysis reaction of the generated propylene oxide on the acidic site of the catalyst, thereby reducing the selectivity of propylene oxide. To solve this problem, the present invention adopts amorphous silica whose acidity is much weaker than that of alumina as the binder of the olefin epoxidation catalyst, thereby reducing the number of acidic sites on the catalyst.

The inventors of the present invention have further found in experiments that although the epoxide selectivity and the hydrogen peroxide conversion rate of the olefin epoxidation reaction can be improved by using amorphous silica, the selectivity of the epoxide and the conversion rate of hydrogen peroxide The conversion rate still needs to be further improved; if a certain amount of alkaline earth metal oxide is added, the epoxide selectivity and hydrogen peroxide conversion rate of the olefin epoxidation catalyst can be significantly improved. This may be due to the fact that although the acidity of amorphous silica is much weaker than that of alumina, there are still acidic sites on the surface of amorphous silica, which may cause side reactions of epoxides. Adding an appropriate amount of alkaline earth metal to the catalyst Oxide, the alkaline earth metal oxide can react with water in the reaction system to generate a corresponding base, so as to neutralize the acidic sites on the surface of the titanium-silicon molecular sieve, thereby improving the epoxide selectivity of the epoxidation catalyst.

In addition, although the use of alkali metal oxides can also achieve the purpose of neutralizing the acidic sites on the surface of titanium-silicon molecular sieves, the alkali formed after the reaction of alkali metal oxides with water in the reaction system is relatively strong, and it is easy to make epoxy Compound side reactions occur, thereby reducing the selectivity of epoxides. Therefore, the olefin epoxidation catalyst of the present invention uses an alkaline earth metal oxide as the metal oxide.

In the epoxidation reaction of propylene, adopt olefin epoxidation catalyst of the present invention as catalyzer, and use the aqueous solution of hydrogen peroxide as oxygenant, can make hydrogen peroxide conversion ratio be higher than 96%, epoxide selectivity is higher than 95%.

The method for preparing the olefin epoxidation catalyst according to the present invention is simple and easy, and does not use or basically does not use organic solvents, so it is green and environment-friendly. The process for epoxidizing olefins according to the invention has a high conversion of hydrogen peroxide and a good selectivity to epoxides.

detailed description

The invention provides an olefin epoxidation catalyst, wherein the catalyst contains a titanium-silicon molecular sieve, a binder and an alkaline earth metal oxide, and the binder is amorphous silicon dioxide.

According to the olefin epoxidation catalyst of the present invention, the catalyst contains an alkaline earth metal oxide. The alkaline earth metal oxide can neutralize the acid sites in the catalyst, reduce the probability of side reactions of epoxidized products, and improve the selectivity of epoxidized products. Preferably, the metal oxide is magnesium oxide and/or calcium oxide.

According to the olefin epoxidation catalyst of the present invention, the catalyst contains titanium silicon molecular sieve. The titanium-silicon molecular sieve can be various molecular sieves formed by substituting some silicon atoms in the skeleton structure with titanium atoms, preferably a titanium-silicon molecular sieve with MFI structure, a titanium-silicon molecular sieve with MWW structure, and a titanium-silicon molecular sieve with MCM structure. and one or more of titanium-silicon molecular sieves with a BETA structure. More preferably, the titanium-silicon molecular sieve is a titanium-silicon molecular sieve with an MFI structure. Most preferably, the titanium-silicon molecular sieve is a hollow titanium-silicon molecular sieve with an MFI structure.

The crystal grains of the hollow titanium-silicon molecular sieve with MFI structure are hollow structures, and the radial length of the cavity part of the hollow grains is _5-300 nanometers. 1. The benzene adsorption measured under the condition of an adsorption time of 1 hour is at least 70 mg/g, and there is a hysteresis loop between the adsorption isotherm and the desorption isotherm of the low-temperature nitrogen adsorption of the hollow titanium-silicon molecular sieve with MFI structure. The hollow titanium-silicon molecular sieve can be prepared by referring to the method disclosed in CN1132699C. The hollow titanium-silicon molecular sieve used in the embodiment of the present invention is a hollow titanium-silicon molecular sieve with the brand HTS produced by Hunan Jianchang Co., Ltd.

When the olefin epoxidation reaction is carried out in the presence of the hollow titanium-silicon molecular sieve with MFI structure, the reaction raw materials and solvent can easily enter the cavity part of the catalyst to contact and react with the titanium-silicon molecular sieve, thereby further strengthening the catalyst. activity; at the same time, the oxyalkylene as the epoxidation product can also be easily detached from the active site of the titanium-silicon molecular sieve, and then diffuse into the cavity of the titanium-silicon molecular sieve, shortening the active site of the oxyalkylene on the titanium-silicon molecular sieve The above residence time further reduces the probability of side reactions of oxidized olefins, thereby further improving the selectivity of the epoxidation reaction.

According to the olefin epoxidation catalyst of the present invention, the catalyst further contains a binder. The binder can endow the titanium-silicon molecular sieve with a certain shape and strength. Although both amorphous silica and alumina are commonly used binders in this field, alumina is more acidic than amorphous silica, and epoxides are prone to side reactions under acidic conditions , thereby reducing the selectivity of epoxides. Therefore, according to the olefin epoxidation catalyst of the present invention, the binder is amorphous silica. The amorphous silicon dioxide is well known to those skilled in the art and will not be described in detail herein.

According to the olefin epoxidation catalyst of the present invention, the weight ratio of the titanium-silicon molecular sieve, amorphous silicon dioxide and alkaline earth metal oxide may be (70-98):(1.5-40):(0.05-25). When the content of the alkaline earth metal oxide is too high, the strength of the catalyst may be insufficient; when the content of the alkaline earth metal oxide is too low, the selectivity of the epoxidation product and the conversion of hydrogen peroxide cannot be greatly improved Rate. From the perspective of further improving the selectivity of epoxidation products and the conversion rate of hydrogen peroxide, the weight ratio of the titanium-silicon molecular sieve, amorphous silicon dioxide and alkaline earth metal oxide is preferably (70-98): (1.5 -25): (0.4-2). Under the premise of ensuring the selectivity of the epoxidation product and the conversion rate of hydrogen peroxide, from the perspective of further improving the strength of the catalyst, the weight ratio of the titanium-silicon molecular sieve, amorphous silicon dioxide and alkaline earth metal oxide is preferably (80-98): (1.5-20): (0.1-15), more preferably (80-98): (1.5-18): (0.4-1.6).

Titanium-silicon molecular sieves are active components in catalysts that catalyze the epoxidation of olefins. Theoretically, the higher the content of titanium-silicon molecular sieves, the higher the catalytic activity of catalysts with titanium-silicon molecular sieves as active components. However, when the epoxidation reaction of olefins is carried out in a fixed-bed reactor process, the catalyst is required to have high crushing strength, so as to avoid the problems of increased catalyst bed lamination and catalyst loss caused by catalyst cracking, so the olefin ring The content of the binder in the oxidation catalyst is usually 80% by weight or more. The inventors of the present invention have found in practice that the content of the binder in the catalyst can be significantly reduced by using the titanium-silicon molecular sieve with a hollow structure of the present invention, thereby improving the catalytic activity of the catalyst. Based on the total weight of the catalyst, the content of the titanium-silicon molecular sieve is preferably 90-97% by weight, the total amount of the amorphous silicon dioxide and the metal oxide is preferably 3-10% by weight, and the The weight ratio of amorphous silica and alkaline earth metal oxide is preferably 1:(0.05-1). Further preferably, based on the total weight of the catalyst, the content of the titanium-silicon molecular sieve is 93-97% by weight, and the total amount of amorphous silicon dioxide and metal oxide is preferably 3-7% by weight, And the weight ratio of the amorphous silicon dioxide to the alkaline earth metal oxide is preferably 1: (0.1-0.3). In this way, not only can the catalyst have high crushing strength, but also high hydrogen peroxide conversion rate and epoxide selectivity can be obtained.

The present invention also provides a method for preparing a catalyst for olefin epoxidation, wherein the method comprises: preparing a mixture containing titanium-silicon molecular sieve, binder source, alkaline earth metal oxide and water, and forming the mixture A molded body is obtained, and the molded body is dried and calcined; the binder source is selected from silica sol, silane with at least two hydrolyzable groups, and siloxane with at least two hydrolyzable groups At least one of them; in the mixture, the weight ratio of titanium silicon molecular sieve, binder source calculated as _SiO2 , alkaline earth metal oxide and water is (70-98): (1.5-40): (0.05- 25): (5-50). In the present invention, the "formed body" refers to a product with a certain shape, such as spherical particles, rod-shaped particles, etc.; the silica sol refers to a colloidal solution of silica with water as the dispersed phase, wherein, The content of silicon may be 20-40% by weight.

According to the present invention, in the mixture, the amount of titanium-silicon molecular sieve, binder source in terms of _SiO2 , alkaline earth metal oxide and water can be adjusted according to the desired amount of titanium-silicon molecular sieve, amorphous silicon dioxide and alkaline earth metal in the catalyst. The amount of oxide can be properly selected, as long as the amount of titanium-silicon molecular sieve, binder source calculated as _SiO2 , alkaline earth metal oxide and water in the mixture can ensure that titanium-silicon molecular sieve, amorphous The amounts of silicon dioxide and alkaline earth metal oxides only need to meet the aforementioned requirements. Preferably, in the mixture, the weight ratio of titanium-silicon molecular sieve, binder source calculated as _SiO2 , alkaline earth metal oxide and water is (70-98):(1.5-40):(0.05-25): (5-50).

According to the method for preparing an olefin epoxidation catalyst of the present invention, the binder source can be selected from silica sol, silane with at least two hydrolyzable groups, and siloxane with at least two hydrolyzable groups at least one of the Preferably, the binder source contains a silane having at least two hydrolyzable groups and/or a siloxane having at least two hydrolyzable groups. In this way, amorphous silica can be generated in situ through the hydrolysis condensation reaction of the silane with at least two hydrolyzable groups and/or the siloxane with at least two hydrolyzable groups, endowing the titanium silicon molecular sieve with certain shape; on the other hand, at least part of the generated amorphous silica can chemically interact with the silicon hydroxyl groups on the surface of the titanium-silicon molecular sieve, thereby enhancing the bonding strength between the amorphous silica and the titanium-silicon molecular sieve, improving the present invention. The crushing strength of the catalyst can reduce the content of binder in the catalyst.

More preferably, the binder source contains at least one of silane with at least two hydrolyzable groups and siloxane with at least two hydrolyzable groups and silica sol. In this way, the manufacturing cost of the catalyst can be reduced under the condition of ensuring the high strength of the olefin epoxidation catalyst. The ratio between the silane with at least two hydrolyzable groups, the siloxane with at least two hydrolyzable groups, and the silica sol can be properly selected according to the strength of the expected catalyst and is not particularly limited. Preferably, from the perspective of reducing the production cost of the olefin epoxidation catalyst under the premise of making the olefin epoxidation catalyst have sufficient strength, in terms of SiO ₂ , the silica sol and the at least two hydrolyzable The weight ratio of silane groups and/or siloxanes with at least two hydrolyzable groups is 1:(0.02-1).

The silane with at least two hydrolyzable groups and/or the siloxane with at least two hydrolyzable groups can be silane and/or silane with at least two hydrolyzable groups in the molecular structure known to those skilled in the art Or a siloxane with at least two hydrolyzable groups.

Preferably, the silane containing at least two hydrolyzable groups is the silane shown in the following formula 1:

Formula 1

Wherein, at least two of R ₁ , R ₂ , R ₃ and R ₄ are each independently -OR ₁₁ or -OCOR ₁₂ , and at most two of R ₁ , R ₂ , R ₃ and R ₄ are each independently -R ₁₃ , R ₁₁ and R ₁₂ are each independently a C ₁ -C ₅ linear or branched alkyl group, and R ₁₃ is a C ₁ -C ₅ linear or branched alkyl group.

More preferably, the silane with at least two hydrolyzable groups is tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, dimethyldimethoxy One or more of silane, diethyldimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, methyl orthosilicate and ethyl orthosilicate.

Preferably, the siloxane having at least two hydrolyzable groups is the siloxane shown in the following formula 2:

Formula 2

Wherein, at least two of R ₅ , R ₆ , R ₇ , R ₈ , R ₉ and R ₁₀ are each independently -OR ₁₄ or -OCOR ₁₅ , R ₅ , R ₆ , R ₇ , R ₈ , R ₉ and At most four of R ₁₀ are each independently -R ₁₆ , each of R ₁₄ and R ₁₅ is independently a C ₁ -C ₅ straight chain or branched chain alkyl group, and R ₁₆ is a C ₁ -C ₅ straight chain or branched chain alkyl.

In the present invention, C ₁ -C ₅ linear or branched alkyl groups can be, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl , n-pentyl.

More preferably, the siloxane having at least two hydrolyzable groups is 1,3-dimethoxy-1,1,3,3-tetramethyldisiloxane and/or 1,3- Diethoxy-1,1,3,3-tetramethyldisiloxane.

According to the method for preparing an olefin epoxidation catalyst of the present invention, when the binder source contains a silane with at least two hydrolyzable groups and/or a siloxane with at least two hydrolyzable groups, the method It also includes: treating the molded body with an aqueous alkali solution at 20-100° C. for 1-10 hours before the calcination, so that the silane with at least two hydrolyzable groups and/or the silane with at least two The siloxane with a hydrolyzable group undergoes a hydrolysis condensation reaction to form amorphous silica.

The base can be either an organic base or an inorganic base. When the base is an inorganic base, it is preferably a base with an alkali metal as a cation; when the base is an organic base, it is preferably a base that can be decomposed into gas under high temperature conditions. Specifically, the base may be one or more of sodium hydroxide, potassium hydroxide, tetramethylammonium hydroxide and tetraethylammonium hydroxide. The amount of the base can be selected according to the amount of silane and/or siloxane having at least two hydrolyzable groups. Preferably, the concentration of the aqueous alkali solution is 0.1-10 mol%, and the weight ratio of the aqueous alkali solution to the molded body is (0.5-5):1.

According to the preparation method of the present invention, when the binder source contains silica sol, the water in the mixture can come from the silica sol on the one hand; on the other hand, when the amount of water in the silica sol cannot meet the use requirements , You can also add water to make the amount of water meet the requirements of use.

The present invention is not particularly limited to the drying conditions. Generally, the drying temperature can be 60-80° C., the drying time can be 3-8 hours, and the drying pressure can be normal pressure or reduced pressure. pressure.

The calcination can be performed under conditions known to those skilled in the art, and is not particularly limited. Preferably, the calcination conditions include: the calcination temperature is 300-600° C., and the calcination time is 5-15 hours.

According to the preparation method of the present invention, the mixture may also contain auxiliary agents. The present invention does not specifically limit the type of the auxiliary agent, which may be various auxiliary agents commonly used in the art, preferably one or more of glycerin, polyvinylpyrrolidone, methylcellulose and polyvinyl alcohol. The amount of the auxiliary agent can be determined according to the content and type of the titanium-silicon molecular sieve, amorphous silicon dioxide and metal oxide in the catalyst, as well as the strength and catalytic activity of the expected catalyst. Preferably, based on the total amount of the mixture, the additive is used in an amount of 0.5-3% by weight.

According to the preparation method of the present invention, the mixture further contains a surfactant. The surfactant can significantly reduce the surface tension of water, so that the titanium-silicon molecular sieve with a certain degree of hydrophobicity is easily wetted by water, so that the amorphous silicon dioxide can be more uniformly dispersed on the titanium-silicon molecular sieve. The surfactant may be various surfactants known to those skilled in the art, and is not particularly limited. The surfactant may be various water-soluble surfactants and/or oil-soluble surfactants known to those skilled in the art, without particular limitation. The oil-soluble surfactant may be, for example, sorbitan fatty acid ester (Span series) and/or alkylphenol polyoxyethylene ether (OP-10). The oil-soluble surfactant is preferably sorbitan monolaurate (Span20), sorbitan monopalmitate (Span40), sorbitan monostearate (Span60), sorbitan tristearate Esters (Span65), sorbitan monooleate (Span80), sorbitan trioleate (Span85), nonylphenol ethoxylates (TX-10), octylphenol ethoxylates (OPE- 10) and one or more of dodecylphenol polyoxyethylene ether. The water-soluble surfactant can be, for example, polyoxyethylene sorbitan fatty acid ester (Tween series), polyoxyethylene fatty acid ester, polyoxyethylene fatty alcohol ether (AEO series), polyoxyethylene-polyoxypropylene copolymer One or more of substances and alkanolamides (Ninol, Ninol). The water-soluble surfactant is preferably polyoxyethylene sorbitan monolaurate (Tween20), polyoxyethylene sorbitan monopalmitate (Tween40), polyoxyethylene sorbitan monostearate (Tween60 ), polyoxyethylene sorbitan monooleate (Tween80) and polyoxyethylene sorbitan trioleate (Tween85). The amount of the surfactant can be determined according to the amount and type of the titanium-silicon molecular sieve, amorphous silicon dioxide and metal oxide used. Preferably, based on the total amount of the mixture, the amount of the surfactant is 0.001-0.2% by weight.

The present invention also provides a method for epoxidizing olefins, which comprises contacting olefins with hydrogen peroxide in a solvent in the presence of a catalyst in a fixed-bed reactor, wherein the catalyst is the catalyst.

Olefin epoxidation catalysts according to the invention have high hydrogen peroxide conversion and epoxide selectivity, so the process for epoxidizing olefins according to the invention also has high hydrogen peroxide conversion and epoxide selectivity .

Because the method for epoxidizing olefins of the present invention improves hydrogen peroxide conversion rate and epoxide selectivity by using the catalyst provided by the invention, so the present invention is not particularly limited for other conditions of epoxidizing olefins, can adopt The epoxidation reaction of olefins is carried out under various conditions well known to those skilled in the art, as long as the catalyst used is the catalyst provided by the present invention.

Preferably, the molar ratio of solvent:alkene:hydrogen peroxide is (4-15):(0.5-5):1. The olefin can be selected from olefins with 2-8 carbon atoms, for example: propylene, butene and its isomers, pentene and its isomers, hexene and its isomers, heptene and its isomers, isomers and octene and its isomers. Preferably, the olefin is propylene. The solvent may be selected from water, acetonitrile and fatty alcohols with 1-6 carbon atoms. The fatty alcohols with 1-6 carbon atoms are, for example, methanol, ethanol, propanol and its isomers, butanol and its isomers, pentanol and its isomers, hexanol and its isomers. Preferably, the solvent is methanol. The conditions of the contact are well known to those skilled in the art, for example, the temperature of the contact can be 30-90°C, the contact can be carried out at a pressure of 0.5-4.5MPa and a pH of the reaction system of 5-8, The liquid hourly space velocity can be 0.1-7h ^-1 . The liquid hourly space velocity in the present invention is the liquid volume space velocity.

In the present invention, the amount (weight, weight ratio or weight percentage) of solid substances such as the titanium-silicon molecular sieve, the alkaline earth metal oxide, and the molded body is calculated on a dry basis, the so-called "dry basis "Weight" refers to the weight of the sample after being calcined at 800°C for 2 hours.

The present invention is described in more detail below in conjunction with examples.

In the following examples, with reference to the method specified in GB3635-1983, the crushing strength of the catalyst was measured on a model QCY-602 crushing strength tester (manufactured by the Alkali Research Institute of the Ministry of Chemical Industry).

The composition of the catalyst was determined by X-ray fluorescence spectrometry (XRF) on a Philips PW-2400 X-ray fluorescence spectrometer.

Gas chromatography was used to analyze the composition of the epoxidized product: MTBE was used as the internal standard, an Agilent-6890 chromatograph was used, and a 30m×0.25mm FFTP capillary column was used, and the injection volume was 1.0μL. The port temperature is 180°C, the temperature of the capillary column is maintained at 60°C for 4 minutes, then increased to 200°C at a rate of 20°C/min, and maintained for 4 minutes, using a flame ionization detector (FID), the detection chamber temperature is 240°C.

The concentration of hydrogen peroxide before and after the reaction was analyzed by indirect iodometric titration, so as to calculate the conversion rate of hydrogen peroxide.

Example 1

This example is used to illustrate the olefin epoxidation catalyst and its preparation method and the method for epoxidizing olefin according to the present invention.

Mix 100g of titanium-silicon molecular sieve powder (Hunan Jianchang Co., Ltd., brand HTS) with 1g of magnesium oxide and 10g of tetramethoxysilane (Qingdao Century Star Chemical Reagent Co., Ltd.), and add 5g of silica sol (silicon dioxide Content 30% by weight), 0.2gSpan80, 2g polyvinyl alcohol (Sanming Dinghui Chemical Co., Ltd., brand name is polyvinyl alcohol 2099), 1g celadon powder (Dongming County Zhuwa Tianjing Rubber Factory) and 50g water mix evenly, It was then extruded and pelletized, followed by drying at 70°C for 4 hours. The resulting shaped body had dimensions of 2×2 mm.

Take 100 g of the above molded body and put it into a 500 mL three-necked flask, add 200 g of 10 mol% sodium hydroxide aqueous solution, and heat the above mixture to 90°C with stirring, and keep it for 6 hours. Then, filter to obtain a solid phase, and wash the obtained solid phase with deionized water until neutral. Next, the obtained solid phase was dried at 120° C. for 3 hours, and finally calcined at 550° C. for 3 hours, thereby obtaining the catalyst according to the present invention. It was determined that the strength of the catalyst was 160N/cm; by XRF analysis, the content of titanium-silicon molecular sieve in the catalyst was 93.2% by weight, and the weight ratio of amorphous silica to magnesium oxide was 1:0.2.

14g of catalyst is installed in the constant temperature reaction zone of the fixed-bed tubular reactor, and the upper and lower parts of the catalyst are filled with ceramic ring fillers, and the airtightness of the whole reaction system is kept intact. Make the propylene and liquid stream enter the reaction zone in an upward flow mode, wherein the molar ratio of methanol: propylene: hydrogen peroxide in the liquid stream is 6:2:1, add ammonia water to the liquid stream, so that the liquid The pH of the stream was 5.3, while 0.98% by weight of Span 80 and 0.06% by weight of Tween 80 were added to the liquid stream. Control the reaction temperature at 40°C, the reaction pressure at 2.5MPa, and the liquid hourly space velocity at 1.5h ^-1 . Sampling and analysis of the reaction product revealed that the conversion rate of hydrogen peroxide was 98.5%, and the selectivity of propylene oxide was 97.7%.

Comparative example 1

The catalyst was prepared by the same method as in Example 1, except that magnesium oxide was not added. As determined by XRF analysis, the content of the titanium-silicon molecular sieve in the obtained catalyst was 94.2% by weight, and the strength of the catalyst was 60 N/cm.

The epoxidation reaction was carried out in the same manner as in Example 1, except that the catalyst used was the catalyst prepared in Comparative Example 1. In the epoxidation reaction, the conversion rate of hydrogen peroxide was 97.3%, and the selectivity of propylene oxide was 89.1%.

Comparative example 2

The catalyst was prepared by the same method as in Example 1, except that instead of adding magnesium oxide, 1 g of zinc oxide was added. The strength of the catalyst is 65N/cm; determined by XRF analysis, the content of titanium silicon molecular sieve in the catalyst is 93.4% by weight, and the weight ratio of amorphous silicon dioxide to zinc oxide is 1:0.2.

The epoxidation reaction was carried out in the same manner as in Example 1, except that the catalyst used was the catalyst prepared in Comparative Example 2. In this epoxidation reaction, the conversion rate of hydrogen peroxide was 97.2%, and the selectivity of propylene oxide was 90.5%.

Example 2

This example is used to illustrate the olefin epoxidation catalyst and its preparation method and the method for epoxidizing olefin according to the present invention.

The olefin epoxidation catalyst was prepared in the same manner as in Example 1, except that the amount of titanium-silicon molecular sieve powder (Hunan Jianchang Co., Ltd., trade name HTS) was 80 g, the amount of magnesium oxide was 3 g, and the amount of tetraethoxy The amount of silane (Qufu Chenguang Chemical Co., Ltd.) used was 64 g, the amount of silica sol (the content of silicon dioxide was 30% by weight) was 30 g, the amount of Span80 was 2 g, and the amount of water was 20 g. It was determined that the strength of the catalyst was 180 N/cm; determined by XRF analysis, the content of titanium-silicon molecular sieve in the catalyst was 70% by weight, and the weight ratio of amorphous silica to magnesium oxide was 1:0.11.

The epoxidation reaction was carried out in the same manner as in Example 1, except that the catalyst used was the catalyst prepared in Example 2. Sampling and analysis of the reaction product showed that the conversion rate of hydrogen peroxide was 94.4%, and the selectivity of propylene oxide was 98.5%.

Example 3

This example is used to illustrate the olefin epoxidation catalyst and its preparation method and the method for epoxidizing olefin according to the present invention.

The olefin epoxidation catalyst was prepared in the same manner as in Example 1, except that the amount of titanium-silicon molecular sieve powder (Hunan Jianchang Co., Ltd., brand name: HTS) was 120 g, and the amount of calcium oxide was 0.5 g. The amount of ethoxysilane (Qufu Chenguang Chemical Co., Ltd.) was 7 g, the amount of silica sol (the content of silicon dioxide was 30% by weight) was 2 g, and the amount of Tween20 was 0.15 g. It was determined that the strength of the catalyst was 120N/cm; by XRF analysis, the content of titanium-silicon molecular sieve in the catalyst was 97% by weight, and the weight ratio of amorphous silica to magnesium oxide was 1:0.2.

The epoxidation reaction was carried out in the same manner as in Example 1, except that the catalyst used was the catalyst prepared in Example 2. Sampling and analysis of the reaction product showed that the conversion rate of hydrogen peroxide was 99.8%, and the selectivity of propylene oxide was 98.2%.

Example 4

This example is used to illustrate the olefin epoxidation catalyst and its preparation method and the method for epoxidizing olefin according to the present invention.

Mix 100g of titanium-silicon molecular sieve powder (Hunan Jianchang Co., Ltd., brand HTS), with 2g of magnesium oxide, 70g of silica sol (mass fraction is 30% by weight), 0.2g of Span80, 2g of polyvinyl alcohol (Sanming Dinghui Chemical Co., Ltd. , the brand is polyvinyl alcohol 2099), 1g of Tianjing powder (Dongming County Zhuwa Tianjing Rubber Factory) and 20g of water are mixed, mixed evenly and then extruded. Calcined at 550° C. for 3 hours to obtain the catalyst according to the invention. It was determined that the strength of the catalyst was 165 N/cm; by XRF analysis, the content of titanium-silicon molecular sieve in the catalyst was 81% by weight, and the weight ratio of amorphous silica to magnesium oxide was 1:0.08.

The epoxidation reaction was carried out in the same manner as in Example 1, except that the catalyst used was the catalyst prepared in Example 4. Sampling and analysis of the reaction product showed that the conversion rate of hydrogen peroxide was 96.4%, and the selectivity of propylene oxide was 95.2%.

Comparative example 3

The catalyst was prepared by the same method as in Example 4, except that alumina was used instead of silica sol. The strength of the catalyst is 90N/cm; determined by XRF analysis, the content of titanium silicon molecular sieve in the catalyst is 82% by weight, and the weight ratio of alumina to magnesia is 1:0.09.

The epoxidation reaction was carried out in the same manner as in Example 1, except that the catalyst used was the catalyst prepared in Comparative Example 3. In the epoxidation reaction, the conversion rate of hydrogen peroxide was 93.6%, and the selectivity of propylene oxide was 90.5%.

Comparative example 4

The catalyst was prepared according to the method in Example 2 of CN1132200 by using hollow titanium-silicon molecular sieve powder (Hunan Jianchang Co., Ltd., brand name: HTS). The strength of the catalyst is 100 N/cm; determined by XRF analysis, the content of titanium silicon molecular sieve in the catalyst is 79% by weight, and the weight ratio of alumina to magnesia is 1:0.27.

The epoxidation reaction was carried out in the same manner as in Example 1, except that the catalyst used was the catalyst prepared in Comparative Example 4. In this epoxidation reaction, the conversion rate of hydrogen peroxide was 90.4%, and the selectivity of propylene oxide was 90.3%.

Example 5

This example is used to illustrate the olefin epoxidation catalyst and its preparation method and the method for epoxidizing olefin according to the present invention.

Mix 100g of titanium-silicon molecular sieve powder (Hunan Jianchang Co., Ltd., brand HTS), 2g of magnesium oxide, and 70g of tetramethoxysilane (Qingdao Century Star Chemical Reagent Co., Ltd.), and add 0.2g of Span80 and 2g of polyethylene after mixing Alcohol (Sanming Dinghui Chemical Co., Ltd., the brand is polyvinyl alcohol 2099), 1g of Tianjing powder (Dongming County Zhuwa Tianjing Rubber Factory) and 50g of water are mixed evenly, then extruded and pelletized, and then heated at 70°C Let dry for 4 hours. The resulting shaped body had dimensions of 2×2 mm.

Take 100 g of the above molded body and put it into a 500 mL three-necked flask, add 200 mL of 20% by weight aqueous sodium hydroxide solution, heat the above mixture to 90°C with stirring, and keep it for 6 hours. Then, filter to obtain a solid phase, and wash the obtained solid phase with deionized water until neutral. Next, the obtained solid phase was dried at 120° C. for 3 hours, and finally calcined at 550° C. for 3 hours, thereby obtaining the catalyst according to the present invention. It was determined that the strength of the catalyst was 200N/cm; by XRF analysis, the content of titanium silicon molecular sieve in the catalyst was 75% by weight, and the weight ratio of amorphous silica to magnesium oxide was 1:0.07.

The epoxidation reaction was carried out in the same manner as in Example 1, except that the catalyst used was the catalyst prepared in Example 5. Sampling and analysis of the reaction product showed that the conversion rate of hydrogen peroxide was 95.8%, and the selectivity of propylene oxide was 95.3%.

The above examples show that the catalysts according to the invention exhibit high hydrogen peroxide conversion and epoxide selectivity in the epoxidation of olefins.

Claims (15)

1. A preparation method for a catalyst for olefin epoxidation, characterized in that the method comprises: preparing a mixture containing titanium-silicon molecular sieve, binder source, alkaline earth metal oxide and water, molding the mixture to obtain A molded body, and the molded body is dried and calcined, wherein the molded body is treated with an aqueous alkali solution at 20-100° C. for 1-10 hours before the roasting; the binder source is A silane with at least two hydrolyzable groups and/or a siloxane with at least two hydrolyzable groups; or the binder source is a silane with at least two hydrolyzable groups and a silane with at least two hydrolyzable groups At least one of the siloxanes of the group and silica sol; In the mixture, the titanium silicon molecular sieve, SiO _The weight ratio of the binder source, alkaline earth metal oxide and water is (70-98): (1.5-40): (0.05-25): (5-50). 2. The method according to claim 1, wherein, in the mixture, titanium-silicon molecular sieve, SiO _The amount of binding agent source, alkaline earth metal oxide and water makes in the catalyst finally obtained, titanium-silicon molecular sieve, The weight ratio of amorphous silicon dioxide and alkaline earth metal oxide is (80-98):(1.5-20):(0.1-15). 3. The method according to claim 1, wherein, in the mixture, titanium-silicon molecular sieve, SiO _The amount of binding agent source, alkaline earth metal oxide and water makes in the catalyst finally obtained, titanium-silicon molecular sieve, The weight ratio of amorphous silicon dioxide and alkaline earth metal oxide is (80-98):(1.5-18):(0.4-1.6). 4. The method according to claim 3, wherein, in the mixture, titanium _- silicon molecular sieves, SiO in terms of binder source, alkaline earth metal oxides and water are used in an amount that is based on the total weight of the catalyst that is finally obtained , the content of titanium-silicon molecular sieve is 90-97% by weight, the total amount of amorphous silicon dioxide and alkaline earth metal oxide is 3-10% by weight, the weight ratio of the amorphous silicon dioxide and the alkaline earth metal oxide is is 1: (0.05-1). 5. The method according to any one of claims 1-4, wherein the alkaline earth metal oxide is magnesium oxide and/or calcium oxide. 6. The method according to any one of claims 1-4, wherein the titanium-silicon molecular sieve is a titanium-silicon molecular sieve with MFI structure, a titanium-silicon molecular sieve with MWW structure, a titanium-silicon molecular sieve with MCM structure and a titanium-silicon molecular sieve with One or more of titanium-silicon molecular sieves with BETA structure. 7. The method according to claim 6, wherein, the crystal grain of the titanium-silicon molecular sieve with the MFI structure is a hollow structure, and the radial length of the cavity part of the hollow structure is 5-300 nanometers, and the The titanium-silicon molecular sieve with the structure has a benzene adsorption capacity of at least 70 mg/g measured under the conditions of 25°C, P/P ₀ =0.10, and an adsorption time of 1 hour. The low-temperature nitrogen adsorption of the titanium-silicon molecular sieve with the MFI structure is There is a hysteresis loop between the adsorption isotherm and the desorption isotherm. 8. The method of claim 1, wherein the binder source is at least one of a silane having at least two hydrolyzable groups and a siloxane having at least two hydrolyzable groups and silicon Sol, calculated as SiO ₂ , the weight ratio of the silica sol to the silane with at least two hydrolyzable groups and/or the siloxane with at least two hydrolyzable groups is 1:(0.02-1) . 9. The method according to claim 1, wherein the alkali is one or more of sodium hydroxide, potassium hydroxide, tetramethylammonium hydroxide and tetraethylammonium hydroxide, the alkali The concentration of the aqueous solution is 0.1-10 mol%, and the weight ratio of the aqueous solution of the alkali to the molded body is (0.5-5):1. 10. The method according to claim 1 or 8, wherein the silane having at least two hydrolyzable groups is a silane shown in formula 1, Wherein, at least two of R ₁ , R ₂ , R ₃ and R ₄ are each independently -OR ₁₁ or -OCOR ₁₂ , and at most two of R ₁ , R ₂ , R ₃ and R ₄ are each independently -R ₁₃ , R ₁₁ and R ₁₂ are each independently a C ₁ -C ₅ linear or branched chain alkyl group, and R ₁₃ is a C ₁ -C ₅ linear or branched chain alkyl group; The siloxane having at least two hydrolyzable groups is the siloxane shown in formula 2, Wherein, at least two of R ₅ , R ₆ , R ₇ , R ₈ , R ₉ and R ₁₀ are each independently -OR ₁₄ or -OCOR ₁₅ , R ₅ , R ₆ , R ₇ , R ₈ , R ₉ and At most four of R ₁₀ are each independently -R ₁₆ , each of R ₁₄ and R ₁₅ is independently a C ₁ -C ₅ straight chain or branched chain alkyl group, and R ₁₆ is a C ₁ -C ₅ straight chain or branched chain alkyl. 11. The method according to claim 10, wherein the silane having at least two hydrolyzable groups is tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, ethyltrimethoxy Silane, dimethyldimethoxysilane, diethyldimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, methyl orthosilicate, ethyl orthosilicate One or more; the siloxane having at least two hydrolyzable groups is 1,3-dimethoxy-1,1,3,3-tetramethyldisiloxane and/or 1, 3-diethoxy-1,1,3,3-tetramethyldisiloxane. 12. The method according to claim 1, wherein the calcination conditions include: a calcination temperature of 300-600° C., and a calcination time of 5-15 hours. 13. A method for epoxidizing olefins, the method comprising contacting olefins with hydrogen peroxide in a solvent in the presence of a catalyst in a fixed-bed reactor, characterized in that the catalyst is claimed in claims 1-12 The catalyst prepared by the method described in any one. 14. The method of claim 13, wherein the olefin is propylene. 15. The method according to claim 13, wherein the contacting conditions include: solvent: olefin: the molar ratio of hydrogen peroxide is (4-15): (0.5-5): 1, and the temperature is 30-90 °C, the pressure is 0.5-4.5MPa, the liquid hourly space velocity is 0.1-7h ^-1 , and the pH of the reaction system is 5-8.