Molecular sieve catalyst, preparation method thereof and application of molecular sieve catalyst in catalysis of dimethyl adipate hydrogenation for preparation of 1, 6-hexanediol

Abstract

The invention discloses a molecular sieve catalyst, a preparation method thereof and application of the molecular sieve catalyst in catalyzing hydrogenation of dimethyl adipate to prepare 1, 6-hexanediol. The preparation method comprises the following steps: transferring an aqueous solution containing tetraethoxysilane, tetrapropylammonium hydroxide, a copper salt, a manganese salt and a precipitant into a hydrothermal kettle for a hydrothermal reaction, drying and calcining a precipitate obtained by the reaction, and then reducing with H2 to obtain a molecular sieve catalyst; the molecular sieve catalyst contains copper and manganese, and the mass ratio of the copper to the manganese is (1-50): 1; in the molecular sieve catalyst, the total mass percentage of copper and manganese is 25%-40% based on 100% of the mass of silicon dioxide. The synthesis method of the molecular sieve catalyst is simple, easy to popularize, mild in condition and low in cost; according to the present invention, 1, 6-hexanediol can be obtained at a high yield in the dimethyl adipate hydrogenation reaction.

Description

Technical Field

[0001] The invention relates to the technical field of catalysis, and in particular to a molecular sieve catalyst and a preparation method thereof, and application thereof in catalyzing the hydrogenation of dimethyl adipate to prepare 1,6-hexanediol. Background Art

[0002] 1,6-Hexanediol is an environmentally friendly chemical raw material that does not pollute the environment. It is known as the "new cornerstone of organic synthesis" today because of its excellent properties. 1,6-Hexanediol has a wide range of uses and shows great application potential and commercial value in many fields such as high-performance polyurethane, UV coatings, high-value-added polyesters, environmentally friendly coatings, biodegradable materials, medicines, dyes, etc. Resins and coatings modified with 1,6-Hexanediol have significantly improved water resistance, mechanical strength, oxidation resistance and environmental performance.

[0003] In view of the wide application of 1,6-hexanediol in the chemical industry, a variety of production routes have been developed, namely adipic acid hydrogenation method, biomass method and olefin method. The adipic acid hydrogenation method uses crude oil as raw material, extracts cyclohexane from it and oxidizes it into adipic acid, and then directly hydrogenates or esterifies and hydrogenates to produce 1,6-hexanediol. This method has a stable source of raw materials and is suitable for large-scale industrial production. It is also a commonly used production method in industry. The biomass method uses cellulose to synthesize intermediates through acid catalysis to produce 1,6-hexanediol. This method is environmentally friendly and the raw materials are easy to obtain, but the conversion process is complicated and has not yet been industrialized on a large scale. The olefin method uses olefins such as propylene, butadiene or epoxybutene as raw materials to synthesize 1,6-hexanediol through oxidation, hydrogenation and other reactions. This method is currently less studied and involves more complex organic synthesis steps, so it needs further exploration.

[0004] Before 2005, a few international companies such as BASF of Germany, Bayer and Ube of Japan monopolized the production technology of 1,6-hexanediol. They generally adopted the process of adipic acid esterification followed by catalytic hydrogenation. Due to the technical monopoly, China's 1,6-hexanediol has long relied on imports.

[0005] In industry, traditional CuCr catalysts are often used to hydrogenate dimethyl adipate to produce 1,6-hexanediol. However, the Cr element can have a significant impact on the environment. Therefore, a large number of studies are currently focused on modifying Cu-based catalysts and finding co-catalysts to replace Cr in order to achieve a more environmentally friendly production process.

[0006] Patent specification with announcement number CN101531568B discloses a method for synthesizing 1,6-hexanediol by gas phase hydrogenation of dimethyl adipate, wherein the preparation of the hydrogenation catalyst used in the method comprises the following steps: stirring a mesoporous silica carrier with a catalyst solution containing a copper salt, microwave evaporation, microwave drying and roasting to obtain a hydrogenation catalyst. The catalyst solution containing a copper salt may optionally contain an aluminum salt and / or a manganese salt.

[0007] The patent specification with publication number CN108607562A discloses a catalyst for preparing hexanediol from dialkyl adipate, a preparation method and an application thereof. The catalyst is a supported Cu-based catalyst, which contains Cu element and M, where M refers to one or more of Ni, La, Mo, Mn, Fe, Co, Zn and Sn elements; the Cu element and M are both supported on a carrier, and the carrier is one or both of titanium dioxide and cerium dioxide.

[0008] The patent specification with the publication number CN118384893A discloses a catalyst for preparing 1,6-hexanediol by hydrogenation of dimethyl adipate, which is composed of three non-precious metal elements: Cu, Zn and Mo, wherein the molar ratio of copper to zinc is Cu:Zn=1:(0.6-1.5); the molar amount of molybdenum is 0.2%-1.5% of the sum of the molar amounts of copper and zinc. The catalyst is synthesized by one-step coprecipitation method using Mo-doped CuZn basic carbonate, which is obtained by calcination and activation. The catalyst is used in preparing 1,6-hexanediol by hydrogenation of dimethyl adipate, using 1,4-dioxane as solvent. Summary of the invention

[0009] Among many catalysts, Cu-based catalysts are the most popular due to the Cu element (Cu 0 ) and univalent Cu ions (Cu + ) has become a hot topic in the research of ester hydrogenation catalysts. + can affect the reaction rate by polarizing dimethyl adipate, while Cu 0 The invention provides a molecular sieve catalyst and a preparation method thereof and an application thereof in catalyzing the hydrogenation of dimethyl adipate to prepare 1,6-hexanediol. Mn doping in a Cu molecular sieve catalyst can increase the Cu content in the catalyst. + / Cu 0 The ratio of Mn to Cu can improve the dispersibility of Cu active components, and the introduction of Mn can improve the interaction between Cu active components and the carrier.

[0010] The molecular sieve catalyst provided by the present invention is an S-1 molecular sieve, which belongs to the MFI topological structure and has a unique ten-membered ring cross-channel system. This structure is conducive to the diffusion and reaction of molecules in the channel, and the good thermal stability enables the S-1 molecular sieve to play a role in high-temperature catalytic reactions.

[0011] The synthesis method adopted by the molecular sieve catalyst of the present invention is in-situ synthesis in a hydrothermal reactor. The synthesis method of the molecular sieve catalyst of the present invention is simple and easy to popularize, the conditions are mild, and the cost is low. The molecular sieve catalyst of the present invention can be used to obtain 1,6-hexanediol in a high yield in the hydrogenation reaction of dimethyl adipate, and still performs well in multiple cycles.

[0012] The specific technical solutions are as follows:

[0013] [1] A method for preparing a molecular sieve catalyst, comprising:

[0014] The molecular sieve catalyst was synthesized in situ by using tetraethyl orthosilicate, tetrapropylammonium hydroxide, copper salt and manganese salt in a hydrothermal reactor.

[0015] Furthermore, a method for preparing a molecular sieve catalyst specifically comprises:

[0016] The aqueous solution containing tetraethyl orthosilicate, tetrapropylammonium hydroxide, copper salt, manganese salt and precipitant is transferred to a hydrothermal kettle for hydrothermal reaction, the precipitate obtained by the reaction is dried and calcined, and then reduced with H2 to obtain the molecular sieve catalyst;

[0017] The molecular sieve catalyst contains copper and manganese, and the mass ratio of copper to manganese is 1 to 50:1, such as 2:1, 2.5:1, 4:1, 5:1, 20:1, 25:1, etc., preferably 2 to 20:1;

[0018] In the molecular sieve catalyst, based on 100% of the mass of silicon dioxide, the total mass percentage of copper and manganese is 25% to 40%.

[0019] In the preparation method of the molecular sieve catalyst of the present invention, ethyl orthosilicate undergoes hydrothermal reaction in a tetrapropylammonium hydroxide environment to undergo hydrolysis, and the chemical equation can be expressed as follows:

[0020] (C2H5O)4Si+2H2O=4C2H5OH+SiO2

[0021] With silicon dioxide as the product, this process forms the framework of the molecular sieve.

[0022] In some embodiments, in the method for preparing the molecular sieve catalyst, the mass ratio of ethyl orthosilicate to tetrapropylammonium hydroxide can be 2 to 4:1.

[0023] In the preparation method of the molecular sieve catalyst, the amount of the precipitant added can be excessive so that copper and manganese can be completely precipitated during the hydrothermal reaction.

[0024] In some embodiments, in the method for preparing the molecular sieve catalyst, the ratio of the total molar amount of copper in the copper salt and the manganese in the manganese salt to the molar amount of the precipitant is 1:10 to 15, for example, 1:13.

[0025] The preparation method of the molecular sieve catalyst, in the molecular sieve catalyst, based on the mass of silicon dioxide being 100%, the mass percentage of copper is 20% to 30%, for example, 25.56%.

[0026] In the method for preparing the molecular sieve catalyst, the copper salt may be a divalent copper salt, specifically copper nitrate or the like.

[0027] In the method for preparing the molecular sieve catalyst, the manganese salt may be a divalent manganese salt, specifically manganese nitrate, etc.

[0028] In the method for preparing the molecular sieve catalyst, the precipitant may include at least one of ethylenediamine, urea, and the like.

[0029] In the method for preparing the molecular sieve catalyst, the temperature and time of the hydrothermal reaction will affect the synthesis of the molecular sieve, and a short time or low temperature will result in poor crystallinity of the molecular sieve. In the method for preparing the molecular sieve catalyst, the temperature of the hydrothermal reaction can be 80 to 150°C, preferably 100°C. In the method for preparing the molecular sieve catalyst, the time of the hydrothermal reaction can be 2.5 to 3.5 days, preferably 3 days.

[0030] In the method for preparing the molecular sieve catalyst, the drying temperature may be 55-65°C, preferably 60°C.

[0031] In the method for preparing the molecular sieve catalyst, the drying time can be 5 to 7 hours, preferably 6 hours.

[0032] In the preparation method of the molecular sieve catalyst, calcination can gasify the precipitant added during the synthesis of the molecular sieve. Furthermore, the calcination temperature can be 450-550°C, preferably 500°C.

[0033] In the method for preparing the molecular sieve catalyst, the calcination time can be 3.5 to 4.5 hours, preferably 4 hours.

[0034] The preparation method of the molecular sieve catalyst, the H2 reduction is a necessary step. In the molecular sieve catalyst of the present invention, the active components are mainly reduced Cu, Mn and metal elements Cu and Mn. If there is no H2 reduction process, Cu and Mn exist in a high-valent state and have no activity in the reaction of catalyzing the hydrogenation of dimethyl adipate to prepare 1,6-hexanediol.

[0035] In the method for preparing the molecular sieve catalyst, the temperature of the H2 reduction can be 280-320°C, preferably 300°C.

[0036] In the method for preparing the molecular sieve catalyst, the H2 reduction time can be 3.5 to 4.5 hours, preferably 4 hours.

[0037] [2] A molecular sieve catalyst prepared according to the preparation method described in [1]. The molecular sieve catalyst contains Cu and Mn in its framework and is obtained by in-situ hydrothermal synthesis, thereby achieving framework doping of Cu and Mn in the molecular sieve, which is significantly different from a simple supported catalyst obtained by first preparing a molecular sieve carrier and then loading Cu and Mn on the surface.

[0038] [3] Use of the molecular sieve catalyst according to [2] in catalyzing the hydrogenation of dimethyl adipate to produce 1,6-hexanediol.

[0039] The application includes: using the molecular sieve catalyst to catalyze the hydrogenation of dimethyl adipate to prepare 1,6-hexanediol.

[0040] In some embodiments, the application may specifically include:

[0041] In the presence of the molecular sieve catalyst, dimethyl adipate and a solvent are subjected to hydrogenation treatment at 100-300° C. to prepare 1,6-hexanediol.

[0042] Furthermore, in the application, the solvent may be an organic solvent, specifically may include at least one of n-butanol, 1,4-dioxane, and the like.

[0043] In the application, the volume ratio of dimethyl adipate to the solvent may be 4 to 19:1.

[0044] In the application, the hydrogenation conditions may include any one or more of the following:

[0045] The mass ratio of the molecular sieve catalyst to dimethyl adipate may be 5 to 7:100;

[0046] The hydrogenation reaction temperature may be 150 to 250°C, such as 230°C, 240°C, 250°C, etc.;

[0047] The hydrogenation reaction pressure may be 3 to 7 MPa, such as 5 MPa, 6 MPa, etc.;

[0048] The hydrogenation reaction time may be 5 to 8 hours, for example 6 hours, 8 hours, etc.

[0049] [4] A method for preparing 1,6-hexanediol by catalytic hydrogenation of dimethyl adipate, comprising: using the molecular sieve catalyst described in [2] to catalytically hydrogenate dimethyl adipate to prepare 1,6-hexanediol.

[0050] In some embodiments, the method for preparing 1,6-hexanediol by catalytic hydrogenation of dimethyl adipate may specifically include:

[0051] In the presence of the molecular sieve catalyst, dimethyl adipate and a solvent are subjected to hydrogenation treatment at 100-300° C. to prepare 1,6-hexanediol.

[0052] Furthermore, in the method for preparing 1,6-hexanediol by catalytic hydrogenation of dimethyl adipate, the solvent may be an organic solvent, specifically including at least one of n-butanol, 1,4-dioxane, and the like.

[0053] In the method for preparing 1,6-hexanediol by catalytic hydrogenation of dimethyl adipate, the volume ratio of dimethyl adipate to the solvent can be 4 to 19:1.

[0054] In the method for preparing 1,6-hexanediol by catalytic hydrogenation of dimethyl adipate, the hydrogenation conditions may include any one or more of the following:

[0055] The mass ratio of the molecular sieve catalyst to dimethyl adipate may be 5 to 7:100;

[0056] The hydrogenation reaction temperature may be 150 to 250°C, such as 230°C, 240°C, 250°C, etc.;

[0057] The hydrogenation reaction pressure may be 3 to 7 MPa, such as 5 MPa, 6 MPa, etc.;

[0058] The hydrogenation reaction time may be 5 to 8 hours, for example 6 hours, 8 hours, etc.

[0059] The technical solution adopted by the application described in [3] and the method described in [4] of the present invention is a molecular sieve catalyst hydrogenation catalysis method. The molecular sieve catalyst of the present invention uses non-precious metals copper and manganese as active components.

[0060] Compared with the prior art, the present invention has the following beneficial effects:

[0061] The molecular sieve catalyst synthesis method of the invention is simple and easy to popularize, has mild conditions and low cost; according to the invention, 1,6-hexanediol can be obtained in a high yield in the hydrogenation reaction of dimethyl adipate. DETAILED DESCRIPTION

[0062] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0063] Example 1

[0064] Cu and Mn doped molecular sieve S-1 were synthesized by hydrothermal method: 10.4g of tetraethyl orthosilicate was added to 6.4mL of distilled water, and then 14.6g of 25wt% tetrapropylammonium hydroxide was slowly added to the solution, and stirred overnight at room temperature. 2.9g of Cu(NO3)2·3H2O, 0.2g of Mn(NO3)2·6H2O and 11mL of ethylenediamine were weighed, mixed evenly and added dropwise to the above solution, and finally the solution was transferred to a 50mL hydrothermal kettle and hydrothermally reacted at 100℃ for 3 days. The sample was separated by centrifugation, and the obtained precipitate was dried at 60℃ for 6h and calcined at 500℃ for 4h to obtain the catalyst 25.56%Cu-1.28%Mn@S-1 (the mass percentage of Cu and Mn is based on the mass of SiO2 as 100%, the same below, no further description). The catalyst 25.56% Cu-1.28% Mn@S-1 was placed in a tube furnace for H2 reduction at 300°C for 4 hours to obtain a molecular sieve catalyst that can be used to catalyze the hydrogenation of dimethyl adipate to produce 1,6-hexanediol.

[0065] 5 mL of dimethyl adipate, 95 mL of 1,4-dioxane and 0.4 g of 25.56% Cu-1.28% Mn@S-1 molecular sieve catalyst were added into an autoclave, and the hydrogenation reaction was carried out at 240°C and a hydrogen pressure of 6 MPa for 6 h. The yield of 1,6-hexanediol was 77.19%.

[0066] Example 2

[0067] Referring to Example 1, the difference is that 1 g of Mn(NO3)2·6H2O and 13.4 mL of ethylenediamine are added, and the obtained molecular sieve catalyst is 25.56% Cu-6.39% Mn@S-1, and the yield of 1,6-hexanediol is 87.03%.

[0068] Example 3

[0069] Referring to Example 1, the difference is that 2 g of Mn(NO3)2·6H2O and 16.4 mL of ethylenediamine are added, and the obtained molecular sieve catalyst is 25.56% Cu-12.78% Mn@S-1, and the yield of 1,6-hexanediol is 73.25%.

[0070] Example 4

[0071] Referring to Example 2, the difference is that the hydrogenation reaction is carried out at 230°C, a hydrogen pressure of 6 MPa, and a reaction time of 8 hours. The yield of 1,6-hexanediol is 80.44%.

[0072] Example 5

[0073] Referring to Example 2, the difference is that the hydrogenation reaction is carried out at 250°C, a hydrogen pressure of 5 MPa, and a reaction time of 6 hours. The yield of 1,6-hexanediol is 77.24%.

[0074] Example 6

[0075] Referring to Example 2, the difference was that 95 mL of n-butanol was used instead of 95 mL of 1,4-dioxane. The yield of 1,6-hexanediol was 70.01%.

[0076] Example 7

[0077] Refer to Example 2, except that after the reaction, the catalyst was filtered and washed, and then vacuum dried and reused. After being reused 6 times, the yield of 1,6-hexanediol only decreased by 1.22% from 87.03% and stabilized at about 85.81%.

[0078] Comparative Example 1

[0079] Molecular sieve S-1 was synthesized by hydrothermal method: 10.4g of tetraethyl orthosilicate was added to 6.4mL of distilled water, and then 14.6g of 25wt% tetrapropylammonium hydroxide was slowly added to the solution and stirred overnight at room temperature. Finally, the solution was transferred to a 50mL hydrothermal kettle and hydrothermally reacted at 100℃ for 3 days. The sample was separated by centrifugation, and the resulting precipitate was dried at 60℃ for 6h and calcined at 500℃ for 4h to obtain catalyst S-1. 2.9g Cu(NO3)2·3H2O and 0.2gMn(NO3)2·6H2O were loaded by equal volume impregnation method. After drying, the catalyst was placed in a tubular furnace at 300℃ H2 reduction time for 4h to obtain the molecular sieve catalyst 25.56%Cu-1.28%Mn / S-1 which can be used to catalyze the hydrogenation of dimethyl adipate to prepare 1,6-hexanediol.

[0080] 5 mL of dimethyl adipate, 95 mL of 1,4-dioxane and 0.4 g of 25.56% Cu-1.28% Mn / S-1 molecular sieve catalyst were added into an autoclave, and the hydrogenation reaction was carried out at 240° C. and a hydrogen pressure of 6 MPa for 6 h. The yield of 1,6-hexanediol was 70.05%.

[0081] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A method for preparing a molecular sieve catalyst, characterized in that: include: The aqueous solution containing tetraethyl orthosilicate, tetrapropylammonium hydroxide, copper salt, manganese salt and precipitant is transferred to a hydrothermal kettle for hydrothermal reaction, the precipitate obtained by the reaction is dried and calcined, and then reduced with H2 to obtain the molecular sieve catalyst; The molecular sieve catalyst contains copper and manganese, and the mass ratio of copper to manganese is 1 to 50:1, preferably 2 to 20:1; In the molecular sieve catalyst, based on 100% of the mass of silicon dioxide, the total mass percentage of copper and manganese is 25% to 40%.

2. The preparation method according to claim 1, characterized in that: The mass ratio of ethyl orthosilicate to tetrapropylammonium hydroxide is 2 to 4:1; The ratio of the total molar amount of copper in the copper salt and manganese in the manganese salt to the molar amount of the precipitant is 1:10-15; In the molecular sieve catalyst, based on 100% of the mass of silicon dioxide, the mass percentage of copper is 20% to 30%.

3. The preparation method according to claim 1, characterized in that: The copper salt is a divalent copper salt, including copper nitrate; The manganese salt is a divalent manganese salt, including manganese nitrate; The precipitant includes at least one of ethylenediamine and urea; The temperature of the hydrothermal reaction is 80 to 150°C, preferably 100°C, and the time is 2.5 to 3.5 days; The drying temperature is 55-65°C and the drying time is 5-7h; The calcination temperature is 450-550°C, preferably 500°C, and the calcination time is 3.5-4.5h; The temperature of the H2 reduction is 280-320°C and the time is 3.5-4.5h.

4. The molecular sieve catalyst prepared according to the preparation method according to any one of claims 1 to 3.

5. Use of the molecular sieve catalyst according to claim 4 in catalyzing the hydrogenation of dimethyl adipate to prepare 1,6-hexanediol.

6. A method for preparing 1,6-hexanediol by catalytic hydrogenation of dimethyl adipate, characterized in that: include: The molecular sieve catalyst according to claim 4 is used to catalyze the hydrogenation of dimethyl adipate to prepare 1,6-hexanediol.

7. The method according to claim 6, characterized in that The method specifically comprises: In the presence of the molecular sieve catalyst, dimethyl adipate and a solvent are subjected to hydrogenation treatment at 100-300° C. to prepare 1,6-hexanediol.

8. The method according to claim 7, characterized in that The solvent is an organic solvent, including at least one of n-butanol and 1,4-dioxane; The volume ratio of dimethyl adipate to the solvent is 4 to 19:

1.

9. The method according to any one of claims 6 to 8, characterized in that: The hydrogenation conditions include any one or more of the following: The mass ratio of the molecular sieve catalyst to dimethyl adipate is 5 to 7:100; The hydrogenation reaction temperature is 150-250°C; The hydrogenation reaction pressure is 3-7 MPa; The hydrogenation reaction time is 5 to 8 hours.