Supported catalysts and their preparation methods and methods for gas-phase epoxidation of propylene

Abstract

This invention relates to the fields of inorganic chemistry and catalytic chemistry, and discloses a supported catalyst and its preparation method, as well as a method for the gas-phase epoxidation of propylene. The catalyst comprises a titanium-silicon molecular sieve and gold-tin alloy nanoparticles supported on the titanium-silicon molecular sieve; wherein, based on the total weight of the catalyst, the gold content is 0.01-1 wt%, and the tin content is 0.01-1 wt%; wherein, the proportion of 0-valent Au in the gold element is >95%. The catalyst provided by this invention exhibits high catalytic activity in the gas-phase epoxidation of propylene, with a propylene conversion rate as high as 12-18% and a propylene oxide selectivity of 85-95%.

Description

Technical Field

[0001] This invention relates to the fields of inorganic chemistry and catalytic chemistry, specifically to a supported catalyst and its preparation method, and a method for the gas-phase epoxidation of propylene. Background Technology

[0002] Propylene oxide (PO) is one of the three major propylene derivatives, primarily used in the production of organic chemical raw materials such as polyether polyols and propylene glycol. Polyurethane plastics produced from polyether polyols are essential materials for manufacturing furniture and other household goods, refrigerators and other home appliances, as well as adhesives and sealants. Propylene glycol is also used in food, tobacco, cosmetics, pharmaceuticals, and other areas related to people's lives. The chlorohydrin process for producing PO is the most mature, with high product selectivity and low construction investment, but it causes severe environmental pollution. The co-oxidation process for producing PO has a long process flow, high investment, and strict requirements for raw material quality, but its economic viability is constrained by the market supply and demand of co-products. The HPPO process uses TS-1 molecular sieve as a catalyst and H2O2 as an oxidant to produce propylene oxide; the production process is green and efficient, but the accompanying H2O2 production unit limits the process layout. Therefore, the propylene gas-phase epoxidation route has emerged. Gas-phase epoxidation is a mild reaction with high selectivity, a simple process, and is environmentally friendly, clean, and efficient.

[0003] The Au / TS-1 catalyst exhibits excellent catalytic activity for the gas-phase epoxidation of propylene. Based on the mechanism of the propylene gas-phase epoxidation reaction, Au nanoparticles are the key active sites promoting H₂O₂ formation. Studies have found that Au nanoparticles deposited on the TS-1 support exhibit diverse morphologies, and their catalytic activity is significantly influenced by factors such as particle size, loading, loading location, and chemical state. Au species deposited via the DP method on the TS-1 support typically exist in ionic form (Au...). 1+ Or Au 3+ Therefore, the Au / TS-1 catalyst needs to be activated first to make the Au species appear in a metallic state (Au). 0 Only by employing specific catalysts can the Au / TS-1 catalyst effectively perform its catalytic role in the gas-phase epoxidation of propylene. However, the catalytic activity of the existing Au / TS-1 catalyst for the gas-phase epoxidation of propylene cannot be further improved, especially due to its low propylene conversion rate. Therefore, there is an urgent need to seek new catalysts to enhance the catalytic activity of propylene epoxidation catalysts. Summary of the Invention

[0004] The purpose of this invention is to overcome the problem of low catalytic performance in the gas-phase epoxidation of propylene using existing propylene epoxidation catalysts, and to provide a supported catalyst, its preparation method, and a method for gas-phase propylene epoxidation. The supported catalyst provided by this invention significantly improves propylene conversion and exhibits high propylene oxide selectivity in the gas-phase epoxidation of propylene.

[0005] To achieve the above objectives, the first aspect of the present invention provides a supported catalyst comprising a titanium-silicon molecular sieve and gold-tin alloy nanoparticles supported on the titanium-silicon molecular sieve; wherein, based on the total weight of the catalyst, the content of gold is 0.01-1% by weight and the content of tin is 0.01-1% by weight; wherein, the proportion of 0-valent Au in the gold is >90%.

[0006] Preferably, based on the total weight of the catalyst, the gold content is 0.04-0.8% by weight and the tin content is 0.04-0.8% by weight.

[0007] Preferably, in the catalyst, the particle size of the gold-tin alloy nanoparticles is <5nm, and more preferably <3nm.

[0008] Preferably, the molar ratio of titanium to silicon in the catalyst is 0.005-0.04:1.

[0009] Preferably, the titanium-silicon molecular sieve is selected from one or more of TS-1 molecular sieve, TS-2 molecular sieve, Ti-Beta molecular sieve and Ti-MWW molecular sieve.

[0010] A second aspect of the present invention provides a method for preparing the supported catalyst described in the first aspect, the method comprising the following steps:

[0011] S1. Mix the aqueous solution containing gold compound and the aqueous solution containing tin compound, and adjust the pH of the resulting mixed solution to alkaline to obtain the impregnation solution;

[0012] S2. Under stirring conditions, the impregnation solution is mixed with titanium-silicon molecular sieve for reaction, and then the reaction product is subjected to solid-liquid separation, and the obtained solid product is activated.

[0013] The amount of the aqueous solution containing gold compounds, calculated as Au, is 0.05-5% by weight of the amount of titanium-silicon molecular sieve; the amount of the aqueous solution containing tin compounds, calculated as Sn, is 0.05-5% by weight of the amount of titanium-silicon molecular sieve.

[0014] Preferably, in step S1, the aqueous solution containing the gold compound is selected from one or more of aqueous solutions of chloroauric acid, cesium chloroaurate, and potassium chloroaurate.

[0015] Preferably, in step S1, the concentration of the aqueous solution containing the gold compound is 0.0001-0.1 mol / L, more preferably 0.0005-0.05 mol / L, and even more preferably 0.005-0.05 mol / L.

[0016] Preferably, in step S1, the tin-containing compound aqueous solution is selected from one or more of tin tetrachloride aqueous solution, tin dichloride aqueous solution, and dimethyltin aqueous solution.

[0017] Preferably, in step S1, the concentration of the tin-containing compound aqueous solution is 0.0001-0.1 mol / L, more preferably 0.0005-0.05 mol / L, and even more preferably 0.005-0.05 mol / L.

[0018] Preferably, in step S1, the pH value of the mixture is adjusted to 7-10, more preferably 7-9.

[0019] Preferably, in step S1, the pH adjuster used to adjust the pH value of the mixture is an alkaline solution.

[0020] Preferably, the alkaline solution is selected from one or more of sodium hydroxide solution, potassium hydroxide solution, cesium hydroxide solution, urea solution, sodium carbonate solution, sodium bicarbonate solution, potassium carbonate solution, potassium bicarbonate solution, cesium carbonate solution, and cesium bicarbonate solution.

[0021] Preferably, in step S2, the titanium-silicon molecular sieve has a titanium-silicon molar ratio of 0.005-0.04:1.

[0022] Preferably, in step S2, the titanium-silicon molecular sieve is selected from one or more of TS-1 molecular sieve, TS-2 molecular sieve, Ti-Beta molecular sieve and Ti-MWW molecular sieve.

[0023] Preferably, the amount of the aqueous solution containing gold compounds, calculated as Au, is 0.1-5% by weight of the amount of titanium-silicon molecular sieve; and the amount of the aqueous solution containing tin compounds, calculated as Sn, is 0.1-5% by weight of the amount of titanium-silicon molecular sieve.

[0024] Preferably, in step S2, the reaction conditions include: a temperature of 10-30°C and a time of 4-24 hours.

[0025] Preferably, in step S2, the activation conditions include: a temperature of 150-300°C and a time of 1-5 hours.

[0026] A third aspect of the present invention provides a supported catalyst prepared by the method described in the second aspect above.

[0027] A fourth aspect of the present invention provides a method for the gas-phase epoxidation of propylene, the method comprising: reacting hydrogen, oxygen and propylene in the presence of a protective gas and a catalyst to obtain propylene oxide; wherein the catalyst is the supported catalyst described in the first aspect or the supported catalyst described in the third aspect.

[0028] Preferably, the reaction conditions include a volume flow rate ratio of hydrogen, oxygen, and propylene of 0.5-2:0.5-2:1.

[0029] Preferably, the volumetric flow rate ratio of propylene to protective gas is 1:1-10.

[0030] Preferably, the reaction conditions include: a temperature of 100-250°C and a pressure of 0.1-0.7 MPa.

[0031] Preferably, the reaction conditions include: a temperature of 120-220°C and a pressure of 0.1-0.5 MPa.

[0032] The catalyst provided by this invention uses titanium-silicon molecular sieve as a support and loads gold-tin alloy nanoparticles on the support. The catalyst has a large amount of zero-valent gold and contains specific amounts of gold and tin elements. The catalyst with these characteristics has high catalytic activity in the gas-phase epoxidation reaction of propylene, with a propylene conversion rate as high as 12-18% and a propylene oxide selectivity of 85-95%. Attached Figure Description

[0033] Figure 1 These are the XPS spectra of the catalysts prepared in Example 1 and Comparative Example 1;

[0034] Figure 2 This is a HAADF-STEM image of the catalyst prepared in Example 1. Detailed Implementation

[0035] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0036] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0037] The first aspect of the present invention provides a supported catalyst comprising a titanium-silicon molecular sieve and gold-tin alloy nanoparticles supported on the titanium-silicon molecular sieve.

[0038] In this invention, the synergistic effect of titanium in the titanium-silicon molecular sieve and tin in the gold-tin alloy nanoparticles enhances the catalytic activity of the catalyst, significantly improving propylene conversion. The inventors discovered that the Sn and Ti promoters jointly donate electrons to Au, resulting in more electron-rich Au. 0 The active sites effectively promote the rate-determining step of in-situ synthesis of H2O2 from hydrogen and oxygen, resulting in a high propylene conversion rate when applied to the gas-phase epoxidation reaction of propylene.

[0039] According to the present invention, the gold and tin content in the catalyst has a significant impact on improving propylene conversion and propylene oxide selectivity during the catalytic gas-phase epoxidation of propylene. Specifically, based on the total weight of the catalyst, the gold content can be 0.01-1 wt%, preferably 0.04-0.8 wt%; the tin content can be 0.01-1 wt%, preferably 0.04-0.8 wt%.

[0040] In this invention, the content of gold and tin in the catalyst is determined by ICP.

[0041] According to the present invention, in order to improve the catalytic activity of the catalyst in the gas-phase epoxidation reaction of propylene and increase the propylene conversion and propylene oxide selectivity, the catalyst needs to have a high proportion of 0-valent Au. Specifically, the proportion of 0-valent Au in the gold element is >90%, as determined by XPS detection and calculation.

[0042] In this invention, XPS characterization yielded 0-valent Au(Au) 0 The characteristic peaks are centered at 83-84 eV; XPS peak analysis using XPS peak software showed that the area of ​​the 0-valent Au peak was >90% of the total peak area. XPS measurements were performed on a Thermo Fisher Scientific ESCALab 250 X-ray photoelectron spectrometer, using monochromatic Al Kα X-rays at an energy of 1486.6 eV and a power of 150 W; the narrow scan passthrough energy was 30 eV; and the baseline vacuum during analysis was approximately 6.5 × 10⁻⁶. -8 Pa.

[0043] In this invention, it was found that the particle size of gold-tin alloy nanoparticles has a significant impact on improving the catalytic effect of the catalyst. To enhance the catalytic activity of the catalyst in the gas-phase epoxidation reaction of propylene, and to improve propylene conversion and propylene oxide selectivity, preferably, the particle size of the gold-tin alloy nanoparticles in the catalyst is <5 nm, more preferably <3 nm. The particle size of the gold-tin alloy nanoparticles was observed using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM).

[0044] In this invention, to further improve the catalytic effect of the supported catalyst in the gas-phase epoxidation reaction of propylene, preferably, the molar ratio of titanium to silicon in the catalyst is 0.005-0.04:1. The molar ratio of titanium to silicon is determined and calculated using an X-ray fluorescence spectrometer, specifically a Rigaku Denki Corporation ZSM Primus II X-ray fluorescence spectrometer, with a rhodium target, excitation voltage of 40 kV, and excitation current of 250 mA.

[0045] According to the present invention, the type of titanium-silicon molecular sieve is not limited, as long as it is a molecular sieve containing silicon, titanium and oxygen.

[0046] In some preferred embodiments, the titanium-silicon molecular sieve may be selected from one or more of TS-1 molecular sieve, TS-2 molecular sieve, Ti-Beta molecular sieve and Ti-MWW molecular sieve.

[0047] A second aspect of the present invention provides a method for preparing the supported catalyst described in the first aspect, the method comprising the following steps:

[0048] S1. Mix the aqueous solution containing gold compound and the aqueous solution containing tin compound, and adjust the pH of the resulting mixed solution to alkaline to obtain the impregnation solution;

[0049] S2. Under stirring conditions, the impregnation solution is mixed with the titanium-silicon molecular sieve for reaction, and then the reaction product is subjected to solid-liquid separation, and the obtained solid product is activated.

[0050] In the process of preparing the supported catalyst in this invention, excessive amounts of gold and tin compounds can lead to the aggregation of metal nanoparticles, which can trigger side reactions during the gas-phase epoxidation of propylene and reduce the selectivity of propylene oxide. Conversely, insufficient amounts of gold and tin compounds can reduce the catalytic activity of the prepared catalyst. Therefore, it is necessary to control the amount of gold and tin compounds to ensure that an appropriate amount of gold-tin alloy nanoparticles are loaded onto the titanium-silicon molecular sieve.

[0051] In this invention, the amount of the aqueous solution containing the gold compound, calculated as Au, is 0.05-5% by weight of the amount of the titanium-silicon molecular sieve, preferably 0.1-5% by weight, for example, it can be 0.1% by weight, 0.5% by weight, 1% by weight, 1.5% by weight, 2% by weight, 2.5% by weight, 3% by weight, 3.5% by weight, 4% by weight, 4.5% by weight, or 5% by weight.

[0052] In this invention, the amount of the aqueous solution of the tin-containing compound, calculated as Sn, is 0.05-5% by weight of the amount of the titanium-silicon molecular sieve, preferably 0.1-5% by weight, for example, it can be 0.1% by weight, 0.5% by weight, 1% by weight, 1.5% by weight, 2% by weight, 2.5% by weight, 3% by weight, 3.5% by weight, 4% by weight, 4.5% by weight or 5% by weight.

[0053] This invention does not impose any particular restrictions on the method of mixing the aqueous solutions of gold-containing compounds and tin-containing compounds. Preferably, the mixing of the aqueous solutions of gold-containing compounds and tin-containing compounds can be achieved by stirring at room temperature. Similarly, adjusting the pH of the resulting mixed solution to alkaline can also be achieved by stirring at room temperature.

[0054] In a preferred embodiment, the process of mixing the aqueous solutions of the gold compound and the tin compound can be as follows: first, the gold compound is prepared into an aqueous solution with water, and the tin compound is prepared into an aqueous solution with water, and then the aqueous solutions of the gold compound and the tin compound are mixed to obtain a mixed solution. Unless otherwise specified herein, room temperature refers to 20-30°C.

[0055] According to the present invention, the aqueous solution containing the gold compound can be any aqueous solution containing a gold compound well known to those skilled in the art. Preferably, in step S1, the aqueous solution containing the gold compound is selected from one or more of aqueous solutions of chloroauric acid, cesium chloroaurate, and potassium chloroaurate.

[0056] To further improve the catalytic performance of the catalyst and increase the propylene conversion and propylene oxide selectivity, under preferred conditions, in step S1, the concentration of the aqueous solution containing the gold compound can be 0.0001-0.1 mol / L, preferably 0.0005-0.05 mol / L, and more preferably 0.005-0.05 mol / L.

[0057] According to the present invention, the aqueous solution containing the tin compound can be any aqueous solution well known to those skilled in the art. Preferably, in step S1, the aqueous solution containing the tin compound is selected from one or more of aqueous solutions of tin tetrachloride, tin dichloride, and dimethyltin.

[0058] To further improve the catalytic performance of the catalyst and increase the propylene conversion and propylene oxide selectivity, under preferred conditions, in step S1, the concentration of the aqueous solution containing the tin compound can be 0.0001-0.1 mol / L, preferably 0.0005-0.05 mol / L, and more preferably 0.005-0.05 mol / L.

[0059] In this invention, in step S1, the pH value corresponding to the alkalinity can be 7-10, preferably 7-9, for example 7, 7.5, 8, 8.5 or 9.

[0060] In this invention, specifically, the pH adjuster used to adjust the pH value of the mixture is an alkaline solution; there are no specific limitations on the type and concentration of the alkaline solution, as long as it can adjust the pH value of the mixture to a specific alkalinity.

[0061] In a preferred embodiment, the alkaline solution is selected from one or more of sodium hydroxide solution, potassium hydroxide solution, cesium hydroxide solution, urea solution, sodium carbonate solution, sodium bicarbonate solution, potassium carbonate solution, potassium bicarbonate solution, cesium carbonate solution, and cesium bicarbonate solution.

[0062] According to the present invention, in order to further improve the catalytic activity and selectivity of the prepared catalyst, preferably, in step S1, the molar ratio of titanium to silicon in the titanium-silicon molecular sieve can be 0.005-0.04:1.

[0063] According to the present invention, the type of titanium-silicon molecular sieve is not limited, as long as it is a molecular sieve containing silicon, titanium and oxygen.

[0064] In some preferred embodiments, the titanium-silicon molecular sieve may be selected from one or more of TS-1 molecular sieve, TS-2 molecular sieve, Ti-Beta molecular sieve and Ti-MWW molecular sieve.

[0065] In this invention, the titanium-silicon molecular sieve can be commercially available, prepared according to existing methods, or prepared in-house.

[0066] In one specific embodiment of the present invention, in step (2), the entire process of mixing the impregnation liquid with the titanium silicon molecular sieve for reaction is carried out under continuous stirring conditions, and the resulting reaction product is a suspension.

[0067] According to the present invention, specifically, the solid-liquid separation of the reaction product obtained in step S2 can be performed by various methods well known to those skilled in the art, as long as the solid product and the liquid can be separated. Preferably, the solid-liquid separation method is filtration or centrifugation.

[0068] According to the present invention, in order to further improve the propylene conversion rate and propylene oxide selectivity of the prepared supported catalyst in the propylene gas-phase epoxidation reaction, preferably, in step S2, the reaction conditions include: a temperature of room temperature, specifically 10-30°C; and a time of 4-24 hours.

[0069] In some preferred embodiments of the present invention, in order to improve the catalytic performance of the catalyst in the propylene gas-phase epoxidation reaction and further improve the propylene conversion and propylene oxide selectivity, the activation conditions in step S2 include: a temperature of 150-300°C, for example, 150°C, 180°C, 200°C, 220°C, 250°C, 280°C, or 300°C; and a time of 1-5 hours, for example, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, or 5 hours. In a preferred embodiment, the activation process includes: calcination at 150-300°C for 1-5 hours in an air atmosphere.

[0070] A third aspect of the present invention provides a supported catalyst prepared by the method described in the second aspect above.

[0071] In some preferred embodiments of the present invention, the catalyst comprises a titanium-silicon molecular sieve and gold-tin alloy nanoparticles supported on the titanium-silicon molecular sieve; wherein, based on the total weight of the catalyst, the content of gold is 0.01-1% by weight and the content of tin is 0.01-1% by weight; wherein, the proportion of 0-valent Au in the gold is >90%.

[0072] To improve the catalytic performance of the catalyst, the gold-tin alloy nanoparticles in the catalyst of this invention have a particle size of <5 nm, more preferably <3 nm. The particle size of the gold-tin alloy nanoparticles is obtained by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM).

[0073] Under preferred conditions, the molar ratio of titanium to silicon in the catalyst is 0.005-0.04:1.

[0074] According to the present invention, the type of titanium-silicon molecular sieve is not limited, as long as it is a molecular sieve containing silicon, titanium and oxygen.

[0075] In some preferred embodiments, the titanium-silicon molecular sieve may be selected from one or more of TS-1 molecular sieve, TS-2 molecular sieve, Ti-Beta molecular sieve and Ti-MWW molecular sieve.

[0076] The catalyst prepared by the method of the present invention can be applied to the catalytic gas-phase epoxidation reaction of propylene, and the propylene conversion rate can reach 12-18%, and the propylene oxide selectivity can reach 85-95%.

[0077] A fourth aspect of the present invention provides a method for the gas-phase epoxidation of propylene, the method comprising: reacting hydrogen, oxygen and propylene in the presence of a protective gas and a catalyst to obtain propylene oxide; wherein the catalyst is the supported catalyst described in the first aspect or the supported catalyst described in the third aspect.

[0078] According to the present invention, under preferred conditions, the reaction conditions include a volume flow rate ratio of hydrogen, oxygen, and propylene of 0.5-2:0.5-2:1.

[0079] More preferably, the volumetric flow rate ratio of propylene to the protective gas is 1:1-10. In this invention, the protective gas is nitrogen and / or an inert gas.

[0080] In some preferred embodiments of the present invention, the reaction conditions further include: a temperature of 100-250°C and a pressure of 0.1-0.7 MPa; more preferably, the temperature is 120-200°C and the pressure is 0.1-0.5 MPa.

[0081] In this invention, the method for gas-phase epoxidation of propylene can be carried out in a continuous operation mode. Specifically, after the catalyst is loaded into the reactor, a mixture of hydrogen, oxygen, propylene and protective gas is continuously added to carry out the reaction.

[0082] The present invention does not have any special requirements on the form of the catalyst. The catalyst can be a powder or it can be further loaded onto a carrier for use. Those skilled in the art can choose according to the type of reactor.

[0083] In this invention, the separation of propylene gas-phase epoxidation products from the catalyst can be adjusted according to the morphology of the catalyst and actual needs. For example, when the catalyst is powder, the product separation and catalyst recycling can be achieved by sedimentation, filtration, centrifugation, evaporation, membrane separation, etc. When the catalyst is a molded catalyst supported on a carrier, the molded catalyst can be packed into a fixed-bed reactor and the catalyst can be recovered after the reaction is completed.

[0084] The present invention will be described in detail below through examples, but the scope of protection of the present invention is not limited thereto. Unless otherwise specified, all raw materials used in the following examples are chemically pure reagents.

[0085] In this invention:

[0086] The gold and tin contents in the catalyst were measured by inductively coupled plasma (ICP).

[0087] The particle size of the gold-tin alloy nanoparticles was observed using a high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM).

[0088] The molar ratio of titanium to silicon was determined using X-ray fluorescence spectroscopy with a Rigaku Denki Corporation ZSM Primus II X-ray fluorescence spectrometer. The test conditions were a rhodium target, an excitation voltage of 40 kV, and an excitation current of 250 mA.

[0089] The proportion of Au in the catalyst at zero valence was determined and calculated using XPS. XPS measurements were performed on a Thermo Fisher Scientific ESCALab 250 X-ray photoelectron spectrometer with a monochromatic Al Kα X-ray excitation source of 1486.6 eV and a power of 150 W; the narrow scan penetration energy was 30 eV; and the baseline vacuum during analysis was approximately 6.5 × 10⁻⁶. - 8 Pa.

[0090] Preparation Examples 1-3 are used to illustrate the preparation process of titanium-silicon molecular sieves.

[0091] Preparation Example 1: Preparation of TS-1 Molecular Sieves

[0092] Approximately 3 / 4 of a tetrapropylammonium hydroxide (TPAOH, 20%, purchased from Aldrich, USA) solution was added to a tetraethyl orthosilicate (TEOS) solution to obtain a liquid mixture with a pH of approximately 13. Then, under vigorous stirring, the required amount of anhydrous isopropanol solution of tetrabutyl titanate [Ti(OBu)4] was added dropwise to the resulting liquid mixture. After stirring for 15 minutes, a clear liquid was obtained. Finally, the remaining TPAOH was slowly added to the clear liquid, and the mixture was stirred at 348-353 K for approximately 3 hours to obtain a sol with a chemical composition of 0.03TiO2:SiO2:0.36TPA:35H2O. This sol was then crystallized at 443 K for 3 days. The resulting solid was then filtered, washed with distilled water, dried at 373 K for 5 hours, and then calcined at 823 K for 10 hours to obtain TS-1 molecular sieve. The dosage of TEOS is 42g, the dosage of TPAOH is 73g, the dosage of Ti(OBu)4 is 2g, the dosage of anhydrous isopropanol is 10g, and the dosage of water is 68g.

[0093] Preparation Example 2: Preparation of TS-2 Molecular Sieves

[0094] A certain amount of tetrabutylammonium hydroxide solution (TBAOH, 20%) was mixed with tetraethyl orthosilicate (TEOS). Then, under vigorous stirring, the required amount of anhydrous isopropanol solution of tetrabutyl titanate [Ti(OBu)4] was added dropwise to the resulting transparent liquid mixture. After stirring for 30 minutes, hydrolysis was completed, and a clear liquid was obtained. Finally, twice the required amount of distilled water was added, and the resulting sol was stirred at 348-353 K for 2 hours to remove alcohol. The chemical composition of the obtained sol was 0.03TiO2:SiO2:0.2TBA:20H2O. The sol was crystallized at 443 K for 3 days. The resulting crystallized product was filtered, washed with water, dried at 373 K for 6 hours, and then calcined at 823 K for 16 hours to obtain TS-2 molecular sieve. The dosage of TEOS is 42g, the dosage of TBAOH is 52g, the dosage of Ti(OBu)4 is 2g, the dosage of anhydrous isopropanol is 10g, and the dosage of water is 30g.

[0095] Preparation Example 3: Preparation of Ti-Beta Molecular Sieves

[0096] A certain amount of tetraethylammonium tetrasilicate (TEOS) was added to a solution of tetraethylammonium hydroxide (TEAOH, 20%) and hydrogen peroxide, and hydrolyzed for 2 hours under stirring. Then, a weighed solution of tetrabutyl titanate [Ti(OBu)4] in anhydrous isopropanol was added to the TEOS hydrolysate, and stirring continued for 3 hours to remove the alcohol, finally yielding a sol with the chemical composition TiO2:60SiO2:33TEA:400H2O:20H2O2. Finally, dealuminized P-type molecular sieve seeds were added and stirred vigorously (the amount of seeds added was calculated based on silica in the sol; 4g of seeds were added for every 100g of silica). The resulting mixture was crystallized at 413K for 14 days, and the resulting slurry was filtered, washed with water, dried at 373K for 6 hours, and then calcined at 823K for 12 hours to obtain Ti-Beta molecular sieve. The dosage of TEOS is 42g, the dosage of TEAOH is 81g, the dosage of Ti(OBu)4 is 1.16g, the dosage of anhydrous isopropanol is 10g, and the dosage of hydrogen peroxide is 7.5g.

[0097] Preparation Example 4

[0098] This preparation example illustrates the preparation process of S-1 molecular sieve.

[0099] A solution of tetrapropylammonium hydroxide (TPAOH, 20%, purchased from Aldrich, USA) was added to a solution of tetraethyl orthosilicate (TEOS) to obtain a liquid mixture with a pH of approximately 13. The mixture was stirred at 348-353 K for about 3 hours to obtain a sol with the chemical composition SiO2:0.36TPA:35H2O. This sol was then crystallized at 443 K for 3 days. The resulting solid was then filtered, washed with distilled water, dried at 373 K for 5 hours, and then calcined at 823 K for 10 hours to obtain a molecular sieve sample. The amount of TEOS used was 42 g, TPAOH was 73 g, and water was 68 g.

[0100] Test Example 1

[0101] The molar ratio of titanium to silicon in the molecular sieves prepared in Examples 1-4 was calculated and is shown in Table 1.

[0102] Table 1

[0103] serial number Molecular sieve number Titanium-silicon molar ratio in molecular sieves Preparation Example 1 TS-1 0.025 Preparation Example 2 TS-2 0.027 Preparation Example 3 Ti-Beta 0.015 Preparation Example 4 S-1 /

[0104] Examples 1-10 and Comparative Examples 1-4 are used to illustrate the preparation process of the catalyst.

[0105] Example 1

[0106] S1. Mix the chloroauric acid aqueous solution and the tin tetrachloride aqueous solution evenly, and then add sodium hydroxide solution to adjust the pH value of the resulting mixed solution to 7.7 to obtain the impregnation solution. The concentration of the chloroauric acid aqueous solution is 0.03 mol / L, and the concentration of the tin tetrachloride aqueous solution is 0.03 mol / L.

[0107] S2. Under continuous stirring, TS-1 molecular sieve is added to the impregnation solution to carry out the reaction at a temperature of 20°C for 6 hours to obtain a suspension. The suspension is then filtered, and the filter residue is activated. The activation conditions include: air atmosphere and calcination at 200°C for 2 hours to obtain a catalyst.

[0108] The amount of chloroauric acid aqueous solution (calculated as Au) is 2.5% by weight of the amount of TS-1 molecular sieve; the amount of tin tetrachloride aqueous solution (calculated as Sn) is 2.5% by weight of the amount of TS-1 molecular sieve.

[0109] Example 2

[0110] S1. Mix the chloroauric acid aqueous solution and the tin tetrachloride aqueous solution evenly, and then add potassium hydroxide solution to adjust the pH value of the resulting mixed solution to 8.1 to obtain the impregnation solution. The concentration of the chloroauric acid aqueous solution is 0.05 mol / L, and the concentration of the tin tetrachloride aqueous solution is 0.05 mol / L.

[0111] S2. Under continuous stirring, TS-2 molecular sieve is added to the impregnation solution to carry out the reaction at a temperature of 22°C for 8 hours to obtain a suspension. The suspension is then filtered, and the filter residue is activated under the following conditions: air atmosphere and calcination at 180°C for 2.5 hours to obtain a catalyst.

[0112] The amount of chloroauric acid aqueous solution (calculated as Au) is 2.5% by weight of the amount of TS-2 molecular sieve; the amount of tin tetrachloride aqueous solution (calculated as Sn) is 2.5% by weight of the amount of TS-2 molecular sieve.

[0113] Example 3

[0114] S1. Mix the chloroauric acid aqueous solution and the tin tetrachloride aqueous solution evenly, and then add cesium hydroxide solution to adjust the pH value of the resulting mixed solution to 8.2 to obtain the impregnation solution. The concentration of the chloroauric acid aqueous solution is 0.08 mol / L, and the concentration of the tin tetrachloride aqueous solution is 0.08 mol / L.

[0115] S2. Under continuous stirring, Ti-Beta molecular sieve is added to the impregnation solution to carry out the reaction at a temperature of 25°C for 10 hours to obtain a suspension. The suspension is then filtered, and the filter residue is activated under the following conditions: air atmosphere and calcination at 150°C for 4 hours to obtain a catalyst.

[0116] The amount of chloroauric acid aqueous solution (calculated as Au) is 2.5% by weight of the amount of Ti-Beta molecular sieve; the amount of tin tetrachloride aqueous solution (calculated as Sn) is 2.5% by weight of the amount of Ti-Beta molecular sieve.

[0117] Example 4

[0118] S1. Mix the chloroauric acid aqueous solution and the tin tetrachloride aqueous solution evenly, and then add urea solution to adjust the pH value of the resulting mixed solution to 7.5 to obtain the impregnation solution. The concentration of the chloroauric acid aqueous solution is 0.04 mol / L, and the concentration of the tin tetrachloride aqueous solution is 0.04 mol / L.

[0119] S2. Under continuous stirring, TS-1 molecular sieve is added to the impregnation solution to carry out the reaction at a temperature of 18°C ​​for 12 hours to obtain a suspension. The suspension is then filtered, and the filter residue is activated under the following conditions: air atmosphere and calcination at 220°C for 1.5 hours to obtain a catalyst.

[0120] The amount of chloroauric acid aqueous solution (calculated as Au) is 3.5% by weight of the amount of TS-1 molecular sieve; the amount of tin tetrachloride aqueous solution (calculated as Sn) is 3.5% by weight of the amount of TS-1 molecular sieve.

[0121] Example 5

[0122] S1. Mix the chloroauric acid aqueous solution and the tin tetrachloride aqueous solution evenly, and then add sodium carbonate solution to adjust the pH value of the resulting mixed solution to 8.3 to obtain the impregnation solution. The concentration of the chloroauric acid aqueous solution is 0.01 mol / L, and the concentration of the tin tetrachloride aqueous solution is 0.01 mol / L.

[0123] S2. Under continuous stirring, TS-1 molecular sieve is added to the impregnation solution to carry out the reaction at a temperature of 16°C for 14 hours to obtain a suspension. The suspension is then filtered, and the filter residue is activated. The activation conditions include: air atmosphere and calcination at 250°C for 1 hour to obtain a catalyst.

[0124] The amount of chloroauric acid aqueous solution (calculated as Au) is 1.5% by weight of the amount of TS-1 molecular sieve; the amount of tin tetrachloride aqueous solution (calculated as Sn) is 1.5% by weight of the amount of TS-1 molecular sieve.

[0125] Example 6

[0126] S1. Mix the chloroauric acid aqueous solution and the tin tetrachloride aqueous solution evenly, and then add sodium bicarbonate solution to adjust the pH value of the resulting mixed solution to 7.1 to obtain the impregnation solution. The concentration of the chloroauric acid aqueous solution is 0.03 mol / L, and the concentration of the tin tetrachloride aqueous solution is 0.01 mol / L.

[0127] S2. Under continuous stirring, TS-1 molecular sieve is added to the impregnation solution to carry out the reaction at a temperature of 14°C for 16 hours to obtain a suspension. The suspension is then filtered, and the filter residue is activated under the following conditions: air atmosphere and calcination at 250°C for 3 hours to obtain a catalyst.

[0128] The amount of chloroauric acid aqueous solution (calculated as Au) is 2.5% by weight of the amount of TS-1 molecular sieve; the amount of tin tetrachloride aqueous solution (calculated as Sn) is 0.1% by weight of the amount of TS-1 molecular sieve.

[0129] Example 7

[0130] S1. Mix the chloroauric acid aqueous solution and the tin tetrachloride aqueous solution evenly, and then add potassium bicarbonate solution to adjust the pH value of the resulting mixed solution to 8.8 to obtain the impregnation solution. The concentration of the chloroauric acid aqueous solution is 0.04 mol / L, and the concentration of the tin tetrachloride aqueous solution is 0.09 mol / L.

[0131] S2. Under continuous stirring, TS-1 molecular sieve is added to the impregnation solution to carry out the reaction at a temperature of 12°C for 18 hours to obtain a suspension. The suspension is then filtered, and the filter residue is activated. The activation conditions include: air atmosphere and calcination at 200°C for 2 hours to obtain a catalyst.

[0132] The amount of chloroauric acid aqueous solution (calculated as Au) is 2.5% by weight of the amount of TS-1 molecular sieve; the amount of tin tetrachloride aqueous solution (calculated as Sn) is 4.5% by weight of the amount of TS-1 molecular sieve.

[0133] Example 8

[0134] S1. Mix the chloroauric acid aqueous solution and the tin tetrachloride aqueous solution evenly, and then add cesium carbonate solution to adjust the pH value of the resulting mixed solution to 7.2 to obtain the impregnation solution. The concentration of the chloroauric acid aqueous solution is 0.008 mol / L, and the concentration of the tin tetrachloride aqueous solution is 0.05 mol / L.

[0135] S2. Under continuous stirring, TS-1 molecular sieve is added to the impregnation solution to carry out the reaction at a reaction temperature of 10°C for 20 hours to obtain a suspension. The suspension is then filtered, and the filter residue is activated. The activation conditions include: air atmosphere and calcination at 180°C for 3.5 hours to obtain a catalyst.

[0136] The amount of chloroauric acid aqueous solution (calculated as Au) is 0.1% by weight of the amount of TS-1 molecular sieve; the amount of tin tetrachloride aqueous solution (calculated as Sn) is 2.5% by weight of the amount of TS-1 molecular sieve.

[0137] Example 9

[0138] S1. Mix the chloroauric acid aqueous solution and the tin tetrachloride aqueous solution evenly, and then add cesium bicarbonate solution to adjust the pH value of the resulting mixed solution to 8.9 to obtain the impregnation solution. The concentration of the chloroauric acid aqueous solution is 0.05 mol / L, and the concentration of the tin tetrachloride aqueous solution is 0.002 mol / L.

[0139] S2. Under continuous stirring, TS-1 molecular sieve is added to the impregnation solution to carry out the reaction at a temperature of 25°C for 4 hours to obtain a suspension. The suspension is then filtered, and the filter residue is activated under the following conditions: air atmosphere and calcination at 200°C for 2 hours to obtain a catalyst.

[0140] The amount of chloroauric acid aqueous solution (calculated as Au) is 4.5% by weight of the amount of TS-1 molecular sieve; the amount of tin tetrachloride aqueous solution (calculated as Sn) is 2.5% by weight of the amount of TS-1 molecular sieve.

[0141] Example 10

[0142] The method was carried out in accordance with Example 1, except that potassium carbonate solution was added to adjust the pH of the resulting mixture.

[0143] Comparative Example 1

[0144] The method was implemented according to Example 1, except that S-1 molecular sieve was used instead of TS-1 molecular sieve.

[0145] Comparative Example 2

[0146] The method described in Example 1 is followed, except that an aqueous solution of tin tetrachloride is not added. Specific operations include:

[0147] S1. Add sodium hydroxide solution to the aqueous chloroauric acid solution to adjust the pH of the resulting mixed solution to 7.7 to obtain the impregnation solution. The concentration of the aqueous chloroauric acid solution is 0.03 mol / L.

[0148] S2. Under continuous stirring, TS-1 molecular sieve is added to the impregnation solution to carry out the reaction at a temperature of 25°C for 6 hours to obtain a suspension. The suspension is then filtered, and the filter residue is activated under the following conditions: air atmosphere and calcination at 200°C for 2 hours to obtain a catalyst.

[0149] The amount of chloroauric acid aqueous solution, calculated as Au, is 2.5 times the weight of TS-1 molecular sieve.

[0150] Comparative Example 3

[0151] The method was implemented according to Example 1, except that the amount of tin tetrachloride aqueous solution (based on Sn element) used was 6% by weight of the amount of TS-1 molecular sieve. Specific operations included:

[0152] S1. Mix the chloroauric acid aqueous solution and the tin tetrachloride aqueous solution evenly, and then add sodium hydroxide solution to adjust the pH value of the resulting mixed solution to 7.7 to obtain the impregnation solution. The concentration of the chloroauric acid aqueous solution is 0.03 mol / L, and the concentration of the tin tetrachloride aqueous solution is 0.03 mol / L.

[0153] S2. Under continuous stirring, TS-1 molecular sieve is added to the impregnation solution to carry out the reaction at a temperature of 25°C for 6 hours to obtain a suspension. The suspension is then filtered, and the filter residue is activated under the following conditions: air atmosphere and calcination at 200°C for 2 hours to obtain a catalyst.

[0154] The amount of chloroauric acid aqueous solution (calculated as Au) is 2.5% by weight of the amount of TS-1 molecular sieve; the amount of tin tetrachloride aqueous solution (calculated as Sn) is 6% by weight of the amount of TS-1 molecular sieve.

[0155] Comparative Example 4

[0156] The method was implemented according to Example 1, except that the amount of chloroauric acid aqueous solution (calculated as Au) used was 6% by weight of the amount of TS-1 molecular sieve. Specific operations included:

[0157] S1. Mix the chloroauric acid aqueous solution and the tin tetrachloride aqueous solution evenly, and then add sodium hydroxide solution to adjust the pH value of the resulting mixed solution to 7.7 to obtain the impregnation solution. The concentration of the chloroauric acid aqueous solution is 0.03 mol / L, and the concentration of the tin tetrachloride aqueous solution is 0.03 mol / L.

[0158] S2. Under continuous stirring, TS-1 molecular sieve is added to the impregnation solution to carry out the reaction at a temperature of 25°C for 6 hours to obtain a suspension. The suspension is then filtered, and the filter residue is activated under the following conditions: air atmosphere and calcination at 200°C for 2 hours to obtain a catalyst.

[0159] The amount of chloroauric acid aqueous solution (calculated as Au) is 6% by weight of the amount of TS-1 molecular sieve; the amount of tin tetrachloride aqueous solution (calculated as Sn) is 2.5% by weight of the amount of TS-1 molecular sieve.

[0160] Test Example 2

[0161] The contents of Au and Sn in the catalysts prepared in Examples 1-10 and Comparative Examples 1-4 were tested, and the results are shown in Table 2. The test method was as follows: the contents were determined by SPECTROS ACROSS inductively coupled plasma (ICP) according to the ASTM D5185 standard method.

[0162] XPS was used to detect the characteristic peak positions of Au in the catalysts prepared in Examples 1-10 and Comparative Examples 1-4, and the proportion of Au with zero valence was calculated. The results are shown in Table 2. The XPS spectra of the catalysts prepared in Example 1 and Comparative Example 1 are shown below. Figure 1 As shown.

[0163] The molar ratio of titanium to silicon in the catalysts prepared in Examples 1-10 and Comparative Examples 1-4 was analyzed and calculated using X-ray fluorescence spectroscopy, and the results are shown in Table 2.

[0164] The particle size of the gold-tin alloy nanoparticles in the catalysts prepared in Examples 1-10 and Comparative Examples 1-4 was observed by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), and the results are shown in Table 2. A high-angle annular dark-field scanning transmission electron microscope image of the catalyst prepared in Example 1 is shown below. Figure 2 As shown.

[0165] Table 2

[0166]

[0167]

[0168] Test Example 3

[0169] This test example illustrates the reaction effect of the catalysts prepared in Examples 1-10 and Comparative Examples 1-4 of this invention in the gas-phase epoxidation reaction of propylene. All reagents used in this test example were commercially available chemically pure reagents. The concentrations of each substance after the reaction were quantitatively analyzed using gas chromatography. The instrument used was an Agilent 6890 gas chromatograph, with molecular sieve 5A and PoraBOND U columns, and FID and TCD detectors.

[0170] In the various embodiments and comparative examples:

[0171] Propylene conversion rate % = (moles of propylene in feedstock - moles of propylene in product) / moles of propylene in feedstock × 100%;

[0172] propylene oxide selectivity % = (number of moles of propylene oxide in the product / total number of moles of the product) × 100%.

[0173] The testing procedure was as follows: Catalyst samples prepared in the above examples and comparative examples were placed in a tubular reactor with an inner diameter of 8 mm. The reactor was then heated to 180 °C in a N2 atmosphere, and hydrogen, oxygen, and propylene were introduced to start the reaction. After 1 h of reaction, the products were analyzed online. The catalyst dosage was 0.4 g, and the flow rates of hydrogen, oxygen, propylene, and nitrogen were 2 mL / min, 2 mL / min, 2 mL / min, and 14 mL / min, respectively. The reaction pressure was 0.1 MPa. The catalytic reaction results are shown in Table 3.

[0174] Table 3

[0175]

[0176]

[0177] As can be seen from Table 3, the propylene conversion rate of the catalyst provided in the embodiments of the present invention for the propylene gas-phase epoxidation reaction is significantly higher than that of the comparative example, and the propylene oxide selectivity of the catalyst provided in the embodiments of the present invention for the propylene gas-phase epoxidation reaction is also maintained at a high level.

[0178] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A supported catalyst, characterized in that, The catalyst comprises a titanium-silicon molecular sieve and gold-tin alloy nanoparticles supported on the titanium-silicon molecular sieve; Based on the total weight of the catalyst, the gold content is 0.01-0.52% by weight, and the tin content is 0.22-0.51% by weight; wherein, the proportion of Au (0 valence) in the gold is >90%. A method for preparing a supported catalyst includes the following steps: S1. Mix the aqueous solution containing gold compound and the aqueous solution containing tin compound, and adjust the pH of the resulting mixed solution to alkaline to obtain the impregnation solution; S2. Under stirring conditions, the impregnation solution is mixed with titanium-silicon molecular sieve for reaction. The reaction conditions include: temperature of 10-30℃ and time of 4-24 hours. Then, the obtained reaction product is subjected to solid-liquid separation, and the obtained solid product is activated. The amount of the aqueous solution containing gold compounds, calculated as Au, is 0.05-5% by weight of the amount of titanium-silicon molecular sieve; the amount of the aqueous solution containing tin compounds, calculated as Sn, is 0.05-5% by weight of the amount of titanium-silicon molecular sieve. The activation conditions include a temperature of 150-300℃ and a time of 1-5h.

2. The catalyst according to claim 1, characterized in that, In the catalyst, the particle size of the gold-tin alloy nanoparticles is <5 nm.

3. The catalyst according to claim 2, characterized in that, In the catalyst, the particle size of the gold-tin alloy nanoparticles is <3nm.

4. The catalyst according to claim 1 or 2, characterized in that, In the catalyst, the molar ratio of titanium to silicon is 0.005-0.04:

1.

5. The catalyst according to any one of claims 1-3, characterized in that, The titanium-silicon molecular sieve is selected from one or more of TS-1 molecular sieve, TS-2 molecular sieve, Ti-Beta molecular sieve and Ti-MWW molecular sieve.

6. A method for preparing the supported catalyst according to any one of claims 1-5, characterized in that, The method includes the following steps: S1. Mix the aqueous solution containing gold compound and the aqueous solution containing tin compound, and adjust the pH of the resulting mixed solution to alkaline to obtain the impregnation solution; S2. Under stirring conditions, the impregnation solution is mixed with titanium-silicon molecular sieve for reaction, and then the reaction product is subjected to solid-liquid separation, and the obtained solid product is activated. The amount of the aqueous solution containing gold compounds, calculated as Au, is 0.05-5% by weight of the amount of titanium-silicon molecular sieve; the amount of the aqueous solution containing tin compounds, calculated as Sn, is 0.05-5% by weight of the amount of titanium-silicon molecular sieve.

7. The method according to claim 6, characterized in that, In step S1, the aqueous solution containing the gold compound is selected from one or more of aqueous solutions of chloroauric acid, cesium chloroaurate, and potassium chloroaurate.

8. The method according to claim 6, characterized in that, In step S1, the concentration of the aqueous solution containing the gold compound is 0.0001-0.1 mol / L.

9. The method according to claim 8, characterized in that, In step S1, the concentration of the aqueous solution containing the gold compound is 0.0005-0.05 mol / L.

10. The method according to claim 6, characterized in that, In step S1, the tin-containing compound aqueous solution is selected from one or more of tin tetrachloride aqueous solution, tin dichloride aqueous solution, and dimethyltin aqueous solution.

11. The method according to claim 6, characterized in that, In step S1, the concentration of the aqueous solution containing the tin compound is 0.0001-0.1 mol / L.

12. The method according to claim 11, characterized in that, In step S1, the concentration of the aqueous solution containing the tin compound is 0.0005-0.05 mol / L.

13. The method according to claim 6, characterized in that, In step S1, the pH value of the mixed solution is adjusted to 7-10.

14. The method according to claim 13, characterized in that, In step S1, the pH value of the mixed solution is adjusted to 7-9.

15. The method according to claim 6, characterized in that, In step S1, the pH adjuster used to adjust the pH value of the mixed solution is an alkaline solution.

16. The method according to claim 15, characterized in that, The alkaline solution is selected from one or more of the following: sodium hydroxide solution, potassium hydroxide solution, cesium hydroxide solution, urea solution, sodium carbonate solution, sodium bicarbonate solution, potassium carbonate solution, potassium bicarbonate solution, cesium carbonate solution, and cesium bicarbonate solution.

17. The method according to claim 6, characterized in that, In step S2, the titanium-silicon molecular sieve has a titanium-silicon molar ratio of 0.005-0.04:

1.

18. The method according to claim 6, characterized in that, The amount of the aqueous solution containing gold compounds, calculated as Au, is 0.1-5% by weight of the amount of titanium-silicon molecular sieve; the amount of the aqueous solution containing tin compounds, calculated as Sn, is 0.1-5% by weight of the amount of titanium-silicon molecular sieve.

19. A supported catalyst prepared by the method according to any one of claims 6-18.

20. A method for the vapor-phase epoxidation of propylene, characterized in that, The method includes: reacting hydrogen, oxygen and propylene in the presence of a protective gas and a catalyst to obtain propylene oxide; The catalyst is the supported catalyst according to any one of claims 1-5 or the supported catalyst according to claim 19.

21. The method according to claim 20, characterized in that, The reaction conditions include a volume flow rate ratio of hydrogen, oxygen, and propylene of 0.5-2:0.5-2:

1.

22. The method according to claim 20, characterized in that, The volumetric flow rate ratio of propylene to protective gas is 1:1-10.

23. The method according to claim 20, characterized in that, The reaction conditions include a temperature of 100-250℃ and a pressure of 0.1-0.7MPa.

24. The method according to claim 23, characterized in that, The reaction conditions include a temperature of 120-220℃ and a pressure of 0.1-0.5MPa.

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