Propylene gas phase epoxidation catalyst and preparation method thereof and propylene gas phase epoxidation method

Abstract

The present invention relates to the technical field of propylene gas phase epoxidation, and in particular to a propylene gas phase epoxidation catalyst and a preparation method thereof and a propylene gas phase epoxidation method, the method comprising: (1) mixing and blowing a titanium silicon molecular sieve, an auxiliary agent and a chloroauric acid aqueous solution under a pH of 6-10 to obtain a suspension; (2) calcining a filter residue obtained by filtering the suspension in a hydrogen atmosphere to obtain a propylene gas phase epoxidation catalyst; wherein the auxiliary agent is selected from amino acids and / or polypeptides. The present invention optimizes the gold loading process by using a specific auxiliary agent in combination with a specific blowing method, can increase the content of gold nanoparticles within a particle size range of 1-3 nm, enhance the coordination between Au and TS-1, and improve the catalytic activity of the catalyst, thereby improving the conversion rate of propylene in a propylene gas phase epoxidation reaction.

Description

Technical Field

[0001] The invention relates to the technical field of propylene gas phase epoxidation, and in particular to a propylene gas phase epoxidation catalyst and a preparation method thereof, and a propylene gas phase epoxidation method. Background Art

[0002] Olefin epoxidation is one of the most important reactions in the chemical industry, and epoxidation products are widely used in the production of various commodities. Among the epoxidation products, propylene oxide (PO) is the main bulk chemical and the third largest propylene derivative after polypropylene and acrylonitrile. It is used to produce compounds such as propylene glycol, polyurethane, and polyether polyols. At present, the main industrial propylene oxide production methods include the chlorohydrin method, co-oxidation method, and hydrogen peroxide oxidation method (HPPO). Among them, the chlorohydrin method is the most mature technology, but it produces a large amount of solid waste and wastewater. This process does not meet the requirements of green chemistry and clean production. Therefore, with the increasing requirements for environmental protection, it will eventually be eliminated. The co-oxidation method uses organic peroxides to oxidize propylene to produce propylene oxide. The optional co-oxidants include isobutane hydroperoxide, ethylbenzene hydroperoxide, isopropylbenzene hydroperoxide, etc. This method produces alcohols, ketones or organic acids as by-products. The HPPO method uses H2O2 as an oxidant to synthesize propylene oxide. This method has problems such as short catalyst life, high energy consumption, and the need for matching H2O2.

[0003] The in-situ synthesis of H2O2 using hydrogen and oxygen and the oxidation of propylene to prepare propylene oxide is a new process route with the advantages of being green, simple to operate, and highly selective, and has good industrial prospects. Currently, gold-loaded titanium silicon molecular sieves have achieved good results in this reaction, but in the face of competition from other industrial methods, it is necessary to continue to improve the activity in order to achieve better economic benefits.

[0004] CN105013480A discloses a catalyst with gold as an active component. By adding silver metal to form gold-silver alloy nanoparticles with small particle size, the alloy is used to change the adsorption of oxygen, thereby improving the coke content and coke performance, and improving the catalytic activity and stability. However, its cost is relatively high, and the gold particles in the titanium silicon molecular sieve are large and the load is uneven, resulting in a low conversion rate of propylene; and alkaline waste liquid is generated during the preparation process, so there is still a certain distance from industrialization.

[0005] Therefore, improving the activity of the catalyst to increase the propylene conversion rate is a difficult problem that needs to be solved urgently. Summary of the invention

[0006] The purpose of the present invention is to overcome the technical problems in the prior art that the gold particles loaded in the titanium silicon molecular sieve are large and the loading is uneven, resulting in low catalytic activity in the propylene gas phase epoxidation reaction, and to provide a propylene gas phase epoxidation catalyst and a preparation method thereof and a propylene gas phase epoxidation method.

[0007] In order to achieve the above object, the first aspect of the present invention provides a method for preparing a propylene gas phase epoxidation catalyst, the method comprising:

[0008] (1) mixing titanium silicon molecular sieve, an auxiliary agent and an aqueous solution of chloroauric acid at a pH of 6-10, and aerating to obtain a suspension;

[0009] (2) calcining the filter residue obtained by filtering the suspension in a hydrogen atmosphere to obtain a propylene gas-phase epoxidation catalyst;

[0010] Wherein, the auxiliary agent is selected from amino acids and / or polypeptides.

[0011] The second aspect of the present invention provides a propylene gas-phase epoxidation catalyst prepared according to the method described in the first aspect.

[0012] The third aspect of the present invention provides a method for gas phase epoxidation of propylene, comprising: mixing propylene, hydrogen, oxygen and nitrogen for reaction in the presence of a catalyst, wherein the catalyst comprises the gas phase epoxidation catalyst for propylene described in the second aspect.

[0013] Through the above technical scheme, the present invention uses a specific auxiliary agent to optimize the gold loading process. During the gold loading process, the active components are adjusted and dispersed by adding the auxiliary agent in combination with the introduction of gas, which can increase the content of gold nanoparticles in the range of 1-3nm in the catalyst, enhance the coordination effect of gold and titanium silicon molecular sieve, and thus improve the conversion rate of propylene in the propylene gas phase epoxidation reaction. DETAILED DESCRIPTION

[0014] The endpoints and any values ​​of the ranges disclosed in this article 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0015] As mentioned above, the first aspect of the present invention provides a method for preparing a propylene gas phase epoxidation catalyst, the method comprising:

[0016] (1) mixing titanium silicon molecular sieve, an auxiliary agent and an aqueous solution of chloroauric acid at a pH of 6-10, and aerating to obtain a suspension;

[0017] (2) calcining the filter residue obtained by filtering the suspension in a hydrogen atmosphere to obtain a propylene gas-phase epoxidation catalyst;

[0018] Wherein, the auxiliary agent is selected from amino acids and / or polypeptides.

[0019] In some preferred embodiments of the present invention, the amino acid is selected from cysteine ​​and / or methionine.

[0020] According to the present invention, under preferred conditions, the polypeptide consists of 2-100 amino acids; further preferably, the polypeptide is selected from octreotide and / or glutathione.

[0021] According to the present invention, under preferred conditions, the weight ratio of the chloroauric acid aqueous solution to the chloroauric acid aqueous solution is 100:(0.04-1) in terms of gold; under the above preferred conditions, the obtained propylene gas phase epoxidation catalyst has high catalytic activity.

[0022] According to the present invention, under preferred conditions, the molar ratio of the auxiliary agent to the aqueous chloroauric acid solution is (1-10):1, for example, it can be 1:1, 2:1, 3:1, 5:1, 8:1, 10:1 or any value in the range formed by any two of the above ratios; under the above preferred conditions, the catalytic activity of the propylene gas phase epoxidation catalyst can be improved.

[0023] In the present invention, the concentration of the chloroauric acid aqueous solution can be selected within a wide range. Under preferred conditions, the concentration of chloroauric acid in the chloroauric acid aqueous solution is 0.005-0.5 mol / L, for example, it can be 0.005 mol / L, 0.01 mol / L, 0.05 mol / L, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L or any value in the range formed by any two of the above values.

[0024] According to the present invention, tiny bubbles of less than 2 mm are formed in the mixed liquid, which can improve the dispersion effect of gold and enhance the coordination effect of gold and titanium silicon molecular sieve. Under preferred conditions, in step (1), the aeration includes: introducing a reducing gas into the bottom of the mixed liquid; preferably, the reducing gas is selected from hydrogen-containing gas; further preferably, the volume ratio of the amount of the reducing gas introduced per minute to the total volume of the mixed liquid is 0.5-5:1. Under the above preferred conditions, the size of the bubbles can be controlled by controlling the amount of the reducing gas introduced per minute.

[0025] In the present invention, the gas dispersion device used for aeration should be able to form tiny bubbles of less than 2 mm in the mixed liquid. Preferably, the gas dispersion device is selected from a membrane tube or an aerator.

[0026] According to the present invention, in order to enable gold to be uniformly loaded in the titanium silicalite molecular sieve, under preferred conditions, in step (1), the mixing conditions include: temperature of 10-70° C. and time of 5-36 h.

[0027] According to the present invention, if the roasting temperature is too low or the roasting time is too short, the roasting will be incomplete, and the catalyst will contain a large amount of impurities, which will affect the catalytic performance of the catalyst; if the roasting temperature is too high or the roasting time is too long, the gold particles will aggregate and become larger; under preferred conditions, in step (2), the roasting conditions include: temperature of 100-350°C and time of 2-8h; preferably, the temperature is 150-250°C and time of 3-5h.

[0028] In the present invention, the titanium silicalite molecular sieve may be a titanium silicalite molecular sieve disclosed in the prior art, or may be prepared by a specific method. In some preferred embodiments of the present invention, in order to optimize the catalytic activity of the propylene gas phase epoxidation catalyst, the preparation method of the titanium silicalite molecular sieve comprises:

[0029] The silicon source, the alkaline template, the titanium source and water are mixed uniformly to obtain a titanium silical sol; the compound represented by formula (I) is then added to the titanium silical sol, and the obtained mixture is hydrothermally crystallized and calcined;

[0030]

[0031] wherein i is an integer from 1 to 10; R1, R2 and R3 are each independently selected from a C1-C6 alkyl group;

[0032] In the present invention, the C1-C6 alkyl group refers to an alkyl group having 1 to 6 carbon atoms in total, for example, it can be one of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl and n-hexyl.

[0033] In some preferred embodiments of the present invention, i is an integer of 1-5, that is, the number of methylene groups between silicon and the alkenyl group (-CH2=CH2-) is 1-5, for example, 1, 2, 3, 4 or 5.

[0034] In some preferred embodiments of the present invention, R1, R2 and R3 are independently selected from methyl, ethyl, n-propyl or isopropyl. In the present invention, R1, R2 and R3 may be the same or different. Preferably, R1, R2 and R3 are the same.

[0035] The present invention adds a specific silanization agent (a compound shown in formula (I)) to the titanium silicalite sol, and can prepare a titanium silicalite molecular sieve with a multi-level pore structure through the dispersion force between the alkenyl groups in the silanization agent and the attraction between molecules. The multi-level pore structure is conducive to the diffusion of substances and accelerates mass transfer, thereby improving the catalytic performance of the catalyst in the gas-phase epoxidation reaction of propylene.

[0036] According to the present invention, if the amount of the silanization agent (the compound shown in formula (I)) is too high, the crystallization performance of the titanium silical sol will deteriorate; if the amount of the silanization agent (the compound shown in formula (I)) is too low, the pore size, specific surface area, etc. of the obtained titanium silicalite molecular sieve will be reduced, affecting mass transfer; under preferred conditions, in step (1), the silicon source is calculated as SiO2, and the molar ratio of the silicon source to the compound shown in formula (I) is 1: (0.01-0.3), preferably 1: (0.01-0.2); more preferably 1: (0.03-0.15).

[0037] In some preferred embodiments of the present invention, the silicon source is calculated as SiO2, the alkaline template is calculated as N when it contains nitrogen, and the alkaline template is calculated as OH when it does not contain nitrogen. - The molar ratio of the silicon source, the alkaline template and water is 1:(0.05-0.4):(5-40); preferably 1:(0.1-0.3):(5-25).

[0038] According to the present invention, the type of the silicon source can be selected within a wide range. Under preferred conditions, the silicon source is selected from at least one of methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, butyl orthosilicate, silica gel, white carbon black and silica sol.

[0039] According to the present invention, the type of the alkaline template agent can be selected within a wide range. Under preferred conditions, the alkaline template agent is selected from at least one of quaternary ammonium bases, aliphatic amines and aliphatic alcohol amines, preferably at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide.

[0040] In some preferred embodiments of the present invention, the silicon source is calculated as SiO2, the titanium source is calculated as TiO2, and the molar ratio of the silicon source to the titanium source is 1:(0.001-0.04), preferably 1:(0.005-0.025), and more preferably 1:(0.01-0.02).

[0041] According to the present invention, the type of the titanium source can be selected within a wide range. Under preferred conditions, the titanium source is selected from an organic titanium source and / or an inorganic titanium source; further preferably, the titanium source is selected from at least one of titanium tetrachloride, titanium sulfate, titanium nitrate, tetraethyl titanate, tetrapropyl titanate and tetrabutyl titanate.

[0042] In a preferred embodiment of the present invention, step (1) further comprises: mixing the silicon source, the alkaline template and water, and performing a first stirring at room temperature for 0.1-2 hours, then adding the titanium source during the stirring process, and performing a second stirring for 0.5-6 hours to obtain titanium silicalose. Under preferred conditions, the second stirring time is 0.5-3 hours, more preferably 2-3 hours.

[0043] According to the present invention, under preferred conditions, step (1) further comprises: driving out alcohol after the mixing; driving out alcohol can remove alcohol generated by hydrolysis of silicon source and titanium source, and in the present invention, preferably azeotropic distillation is used to remove alcohol generated in the system, and water lost by azeotropic distillation is supplemented during the driving out alcohol process to ensure that the ratio of each substance in the titanium silica sol meets the above requirements; preferably, the conditions for driving out alcohol include: temperature of 30-100°C and time of 2-10h; more preferably: temperature of 40-90°C and time of 4-10h, and further preferably, the conditions for driving out alcohol include: temperature of 60-70°C and time of 6-8h.

[0044] According to the present invention, under preferred conditions, step (1) further comprises: adding the compound represented by formula (I) to the titanium silical sol and performing a third stirring for 0.1-24 hours, preferably the third stirring time is 0.5-10 hours, more preferably 2-4 hours.

[0045] According to the present invention, under preferred conditions, in step (2), the conditions for hydrothermal crystallization include: heating the mixture to 50-200°C within 0.1-3h, and then performing hydrothermal crystallization at 50-200°C for 10-100h; preferably, performing hydrothermal crystallization at a temperature of 100-200°C for 20-80h; further preferably, the heating time is 0.3-1h; more preferably, the conditions for hydrothermal crystallization include: a temperature of 150-180°C and a time of 20-60h.

[0046] The present invention has no particular limitation on the pressure of hydrothermal crystallization, which may be the autogenous pressure of the crystallization system.

[0047] According to the present invention, under preferred conditions, the method further comprises: washing, filtering and drying the product obtained by hydrothermal crystallization; wherein the washing, filtering and drying processes can be known to those skilled in the art. Exemplarily, the washing temperature can be 20-50°C, the washing solvent can be water, and the amount of the washing solvent is 1-20 times the mass of the crystallized product; the drying conditions can be: the temperature is 40-150°C and the time is 0.5-24h.

[0048] In some preferred embodiments of the present invention, the calcination conditions include: a temperature of 400-800° C. and a time of 1-15 h; preferably a temperature of 500-600° C. and a time of 4-8 h.

[0049] The second aspect of the present invention provides a propylene gas-phase epoxidation catalyst prepared according to the method described in the first aspect.

[0050] According to the present invention, preferably, the propylene gas-phase epoxidation catalyst comprises titanium silicalite and gold nanoparticles supported on the titanium silicalite.

[0051] According to the present invention, preferably, in the catalyst, the content of gold nanoparticles with a particle size of 1-3 nm is greater than 60%.

[0052] According to the present invention, further preferably, the weight content of gold in the propylene gas-phase epoxidation catalyst is 0.04-1 wt %, based on the total amount of the propylene gas-phase epoxidation catalyst.

[0053] The third aspect of the present invention provides a method for gas phase epoxidation of propylene, comprising: mixing propylene, hydrogen, oxygen and nitrogen for reaction in the presence of a catalyst, wherein the catalyst comprises the gas phase epoxidation catalyst for propylene described in the second aspect.

[0054] Under the preferred conditions, the reaction conditions include: temperature of 120-200°C, space velocity of 3-10 L·h -1 ·g -1 ; Further preferably, the reaction conditions also include: the volume ratio of propylene, hydrogen, oxygen and nitrogen is 1: (0.8-1.2): (0.8-1.2): (5-10).

[0055] According to a particularly preferred embodiment of the present invention, the method for preparing a propylene gas phase epoxidation catalyst comprises:

[0056] 1) Preparation of titanium silicate molecular sieve:

[0057] After mixing a silicon source, an alkaline template and water in a molar ratio of 1:(0.1-0.3):(5-25), the mixture is stirred for a first time at room temperature for 0.1-2 hours, and then a titanium source is added during the stirring process, and a second stirring is performed for 2-3 hours to obtain a mixed system; wherein the molar ratio of the silicon source to the titanium source is 1:(0.005-0.025); the mixed system is then subjected to alcoholization to obtain a titanium silical sol; the alcoholization temperature is 60-70°C and the time is 6-8 hours; the compound represented by formula (I) is added to the titanium silical sol and stirred for a third time for 2-4 hours, and the obtained mixture is subjected to hydrothermal crystallization and calcination to obtain a titanium silicalite molecular sieve;

[0058] The molar ratio of the silicon source to the compound represented by formula (I) is 1:(0.01-0.2), and the crystallization conditions are: heating the mixture to 150-180° C. within 0.3-0.6 h, and then performing hydrothermal crystallization at 150-180° C. for 20-60 h;

[0059]

[0060] wherein i is an integer of 1-5; R1, R2 and R3 are the same; R1, R2 and R3 are selected from methyl, ethyl, n-propyl or isopropyl;

[0061] 2) Preparation of the catalyst: under the conditions of pH 6-10 and temperature 40-70°C, the titanium silicon molecular sieve and the auxiliary agent are added to a 0.005-0.5 mol / L chloroauric acid aqueous solution and mixed; then, a reducing gas is introduced into the bottom of the mixed solution; the volume ratio of the amount of reducing gas introduced per minute to the total volume of the mixed solution is (0.5-5):1, to obtain a suspension, wherein the auxiliary agent is selected from amino acids and / or polypeptides; the weight ratio of the chloroauric acid aqueous solution is 100:0.04-1; the molar ratio of the auxiliary agent to the chloroauric acid aqueous solution is (1-10):1;

[0062] In a hydrogen atmosphere, the filter residue obtained by filtering the suspension is calcined at 150-250° C. for 3-5 hours to obtain a propylene gas-phase epoxidation catalyst.

[0063] The present invention will be described in detail below by way of examples. In the following examples, room temperature refers to 25±5°C.

[0064] The content of gold particles with a particle size of 1-3 nm in the catalyst was obtained by TEM testing.

[0065] In the following examples, the silanization agents used are shown in Table 1.

[0066] Table 1

[0067]

[0068] Preparation Example 1

[0069] (1) methyl orthosilicate, tetrapropylammonium hydroxide and water are first stirred at room temperature for 0.5 h, and tetraethyl titanate is added during the stirring process, and a second stirring is performed for 2.5 h to obtain a mixed system; wherein methyl orthosilicate is calculated as SiO2, tetrapropylammonium hydroxide is calculated as N, and tetraethyl titanate is calculated as TiO2, and the molar ratio of methyl orthosilicate, tetrapropylammonium hydroxide, water and tetraethyl titanate is 1:0.1:20:0.015;

[0070] Then, the mixed system was subjected to alcoholization at 70°C for 7 hours to obtain titanium silicalose;

[0071] (2) adding compound 1 (the structural formula is shown in Table 1) to the titanium silicalite, and stirring for a third time at room temperature for 2 hours to obtain a mixture, wherein the molar ratio of compound (1) to tetramethyl silicate is 0.2:1;

[0072] (3) heating the mixture from room temperature (25° C.) to 170° C. within 0.3 h, and performing hydrothermal crystallization at 170° C. for 48 h to obtain a crystallized product;

[0073] The crystallized product was sequentially washed with water, filtered, and dried at 120 °C for 2 h;

[0074] The dried product was calcined at 550°C for 6 hours to obtain titanium silicate molecular sieve TS-1.

[0075] Preparation Example 2-15

[0076] According to the method of Preparation Example 1, titanium silicalite molecular sieves TS-2 to TS-15 were obtained respectively, and their proportions and synthesis conditions are shown in Table 2.

[0077] Table 2

[0078]

[0079]

[0080] Examples 1-6

[0081] 100 mL of deionized water was added to 20.8 mL of chloroauric acid aqueous solution (0.01 mol / L) for dilution, and then the titanium silicon molecular sieve TS-1 and the auxiliary agent obtained in Preparation Example 1 were added. After stirring for 0.3 h, the pH value was adjusted to 7 to obtain a mixed solution. Then, hydrogen was introduced into the mixed solution through an aerator; the flow rate of hydrogen was 300 mL / min; the mixture was stirred at 60°C for 12 h to obtain a suspension, and the residue obtained by filtering the suspension was washed and then vacuum dried at 30°C for 10 h; then, the dried product was calcined at 200°C for 4 h in a hydrogen atmosphere. The amount of each substance and the reaction conditions are shown in Table 3 to obtain catalysts Au / TS-1 to Au / TS-6.

[0082] Examples 7-12 and Comparative Examples 1-14

[0083] The method of Example 1 was followed, except that the amounts of each substance used and the reaction conditions were as shown in Table 3.

[0084] Table 3

[0085]

[0086]

[0087] Note: * refers to the weight ratio of titanium silicon molecular sieve to the chloroauric acid aqueous solution in terms of gold;

[0088] **Auxiliary agent: HAuCl4 refers to the weight ratio of the auxiliary agent to chloroauric acid in the chloroauric acid aqueous solution.

[0089] Test Case

[0090] Au / TS-1 to Au / TS-26 were used as catalysts, respectively, and the catalysts were loaded into a fixed bed reactor at normal pressure, and then propylene, hydrogen, oxygen and nitrogen were introduced respectively to start the reaction, and the volume ratio of propylene: hydrogen: oxygen: nitrogen was 1:1:1:7, the reaction temperature was 160°C, and after the reaction for 1 hour, the product was analyzed online; wherein, the catalyst loading amount was 0.36 g, and the space velocity was 8000 mL·h -1 ·g -1 cat The catalytic reaction results are shown in Table 4.

[0091] In the present invention, gas chromatography is used to analyze the reactants and products in the evaluation system, wherein the gas chromatography analysis conditions are: Agilent-7890B chromatograph, molecular sieve 5A and PoraBONDU chromatographic columns, FID and TCD detectors.

[0092] Propylene conversion % = (moles of propylene in the feedstock - moles of propylene in the product) / moles of propylene in the feedstock × 100%

[0093] Propylene oxide selectivity % = moles of propylene oxide in the product / (moles of propylene in the feed - moles of propylene in the product) × 100%

[0094] Table 4

[0095] catalyst *1-3nm / % Propylene conversion rate / % Propylene oxide selectivity / % Example 1 Au / TS-1 64.3 9.3 91.1 Example 2 Au / TS-2 60.9 9.1 90.2 Example 3 Au / TS-3 61.9 9.1 89.8 Example 4 Au / TS-4 66.2 8.8 91.0 Example 5 Au / TS-5 61.9 9.3 90.0 Example 6 Au / TS-6 63.9 8.8 90.1 Example 7 Au / TS-7 61.2 8.9 89.3 Example 8 Au / TS-8 60.2 8.8 89.9 Example 9 Au / TS-9 62.4 9.2 90.4 Example 10 Au / TS-10 63.6 9.1 90.0 Embodiment 11 Au / TS-11 60.2 8.6 88.3 Example 12 Au / TS-12 60.1 8.5 88.5 Comparative Example 1 Au / TS-13 48.6 6.1 89.8 Comparative Example 2 Au / TS-14 41.6 5.8 85.6 Comparative Example 3 Au / TS-15 46.6 6.6 88.6 Comparative Example 4 Au / TS-16 36.3 3.5 70.1 Comparative Example 5 Au / TS-17 39.2 1.4 13.2 Comparative Example 6 Au / TS-18 41.9 3.6 84.1 Comparative Example 7 Au / TS-19 43.6 3.7 80.1 Comparative Example 8 Au / TS-20 34.6 2.5 75.3 Comparative Example 9 Au / TS-21 46.1 5.2 87.5 Comparative Example 10 Au / TS-22 44.2 5.5 80.1 Comparative Example 11 Au / TS-23 48.7 4.2 82.3 Comparative Example 12 Au / TS-24 47.6 4.3 75.1 Comparative Example 13 Au / TS-25 48.1 4.8 78.9 Comparative Example 14 Au / TS-26 45.2 5.1 84.8

[0096] Note: *1-3nm: The content of gold with a particle size of 1-3nm, based on the total amount of gold in the catalyst.

[0097] It can be seen from the results in Table 1 that the propylene gas-phase epoxidation catalyst prepared in the embodiment of the present invention has high catalytic activity. When used in the propylene gas-phase epoxidation reaction, the conversion rate of propylene is as high as 9.3%, and the selectivity of propylene oxide is as high as 91.1%.

[0098] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing a propylene gas phase epoxidation catalyst, characterized in that: The method comprises: (1) Mixing titanium silicalite, an auxiliary agent and an aqueous solution of chloroauric acid at a pH of 6-10, and aerating to obtain a suspension; (2) calcining the filter residue obtained by filtering the suspension in a hydrogen atmosphere to obtain a propylene gas-phase epoxidation catalyst; Wherein, the auxiliary agent is selected from amino acids and / or polypeptides; The method also includes the preparation of titanium silicon molecular sieve, and the preparation method of titanium silicon molecular sieve includes: The silicon source, the alkaline template, the titanium source and water are uniformly mixed to obtain a titanium silical sol; then the compound represented by formula (I) is added to the titanium silical sol, and the obtained mixture is hydrothermally crystallized and calcined; Formula (I) wherein i is an integer from 1 to 10; R1, R2 and R3 are each independently selected from a C1-C6 alkyl group; The amino acid is selected from cysteine ​​and / or methionine; The polypeptide is selected from octreotide and / or glutathione; In step (1), the blowing gas is a reducing gas.

2. The method according to claim 1, wherein: The weight ratio of the chloroauric acid aqueous solution to the chloroauric acid aqueous solution is 100:(0.04-1) based on gold. and / or, the molar ratio of the auxiliary agent to the aqueous solution of chloroauric acid is (1-10): 1; And / or, the concentration of chloroauric acid in the chloroauric acid aqueous solution is 0.005-0.5 mol / L.

3. The method according to claim 1 or 2, wherein: In step (1), the aeration includes: introducing reducing gas from the bottom of the mixed liquid.

4. The method according to claim 3, wherein: The reducing gas is selected from hydrogen-containing gases.

5. The method according to claim 3, wherein: In step (1), the volume ratio of the amount of the reducing gas introduced per minute to the total volume of the mixed liquid is (0.5-5):

1.

6. The method according to claim 1 or 2, wherein: In step (2), the calcination conditions include: temperature of 100-350°C and time of 2-8h.

7. The method according to claim 6, wherein: The calcination conditions include: a temperature of 150-250° C. and a time of 3-5 hours.

8. The method according to claim 1 or 2, wherein: i is an integer from 1 to 5; And / or, R1, R2 and R3 are each independently selected from methyl, ethyl, n-propyl or isopropyl.

9. The method according to claim 1 or 2, wherein: The silicon source is calculated as SiO2, the alkaline template is calculated as N when it contains nitrogen, and as OH when it does not contain nitrogen. - The titanium source is calculated as TiO2, and the molar ratio of the silicon source to the compound represented by formula (I) is 1:0.01-0.3; and / or, the molar ratio of the silicon source, the alkaline template and water is 1:0.05-0.4:5-40; And / or, the molar ratio of the silicon source to the titanium source is 1:0.001-0.

04.

10. The method according to claim 1 or 2, wherein: The silicon source is calculated as SiO2, the alkaline template is calculated as N when it contains nitrogen, and as OH when it does not contain nitrogen. - The titanium source is calculated as TiO2, and the molar ratio of the silicon source to the compound represented by formula (I) is 1:0.01-0.2; and / or, the molar ratio of the silicon source, the alkaline template and water is 1:0.1-0.3:5-25; And / or, the molar ratio of the silicon source to the titanium source is 1:0.005-0.

025.

11. The method according to claim 1 or 2, wherein: The conditions of the hydrothermal crystallization include: heating the mixture to 50-200° C. within 0.1-3 h, and then crystallizing at 50-200° C. for 10-100 h; And / or, the calcination conditions include: temperature of 400-800° C. and time of 1-15 h.

12. The method according to claim 1 or 2, wherein: The conditions of the hydrothermal crystallization include: heating the mixture to 50-200° C. within 0.1-3 hours, and then crystallizing at a temperature of 100-200° C. for 20-80 hours.

13. A catalyst for gas phase epoxidation of propylene, characterized in that: Prepared according to the method according to any one of claims 1 to 12.

14. The catalyst according to claim 13, wherein The propylene gas-phase epoxidation catalyst comprises a titanium silicate molecular sieve and gold nanoparticles supported on the titanium silicate molecular sieve.

15. The catalyst according to claim 14, wherein In the catalyst, the content of gold nanoparticles with a particle size of 1-3 nm is greater than 60% based on the total amount of the gold nanoparticles; And / or, based on the total amount of the propylene gas-phase epoxidation catalyst, the weight content of gold in the propylene gas-phase epoxidation catalyst is 0.04-1 wt %.

16. A method for gas phase epoxidation of propylene, characterized in that: The method comprises: mixing propylene, hydrogen, oxygen and nitrogen for reaction in the presence of a catalyst, wherein the catalyst comprises the propylene gas-phase epoxidation catalyst according to any one of claims 13 to 15.

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