Composite catalyst for hydrogenating methyl 3-hydroxypropionate to 1,3-propanediol

Abstract

The present invention discloses a composite catalyst for hydrogenating methyl 3-hydroxypropionate to 1,3-propanediol and a preparation method thereof. The composite catalyst comprises the following components: (a) the main component CuO; (b) the electron promoter barium strontium titanate; (c) one or more of the hydrogenation activity promoters NiO, MnO2, and MoO3; (d) the carrier and pore-expanding agent SiO2. Among them, the hydrogenation activity promoter helps the catalyst activate hydrogen, and the electron promoter barium strontium titanate easily forms active sites for enhancing the conversion of 1,3-propanediol when acting with the main component CuO. Therefore, the composite catalyst has high activity and high product selectivity when used for hydrogenating methyl 3-hydroxypropionate to 1,3-propanediol, and can solve the problems of low activity of the current catalyst for hydrogenating methyl 3-hydroxypropionate and low selectivity of 1,3-propanediol.

Description

Technical Field

[0001] The present invention belongs to the field of catalyst preparation, and particularly relates to a composite catalyst for hydrogenating methyl 3-hydroxypropionate to 1,3-propanediol and a preparation method thereof. Background Art

[0002] 1,3-propanediol (1,3-PDO) is a colorless, odorless, salty, hygroscopic viscous liquid. 1,3-PDO is not only a raw material for producing unsaturated polyesters, plasticizers, surfactants, emulsifiers and demulsifiers, but its main use is as a polymer monomer to synthesize PTT (polytrimethylene terephthalate) fiber with terephthalic acid (PTA). Compared with fibers such as PET, PBT, and PA6, PTT has excellent resilience and dyeability, etc., and can develop personalized fashion fabrics that are comfortable to wear, have good elasticity, rich colors, and diverse tissue changes. With the further maturity of PTT fiber production technology and the further reduction of costs, PTT can gradually replace 5-10% of traditional polyester fibers at a reasonable price difference, and the market prospect is very broad. Among them, 1,3-PDO is the core and key raw material for synthesizing PTT and is irreplaceable.

[0003] Using the hydroformylation reaction of ethylene oxide to obtain the intermediate methyl 3-hydroxypropionate, and then catalytic hydrogenation to obtain 1,3-PDO is the only way to achieve large-scale production of cheap 1,3-PDO. This method has low raw material costs and is easy to scale up the process for large-scale production, providing cheap raw materials for the batch production of PTT fibers. However, compared with the acrolein hydration hydrogenation method and the glycerol enzymatic catalysis method, the process of producing 1,3-propanediol by ethylene oxide methoxylation and hydrogenation reaction has high technical difficulty, especially for the hydrogenation activity of the methyl 3-hydroxypropionate catalyst and the selectivity requirements of the main product, which is the technical core of this process.

[0004] Copper-based methyl 3-hydroxypropionate hydrogenation catalysts have become a research hotspot due to their low production cost, high activity, high selectivity, mild reaction conditions, and good anti-toxicity when combined with other active additives. In Patent CN 1911507A, under the condition of an alcohol solvent, an organic amine is added in advance to complex with a copper salt, and a fatty alcohol orthosilicate and an aluminum fatty alcohol are added as carrier precursors, and then a gelling agent is added and heated to form a sol-gel to obtain a copper-based single-component catalyst with a low loading amount, effectively improving the anti-sintering performance and service life of the catalyst. Since only a single-component copper is used in the preparation process, its catalytic activity still needs to be improved; in addition, the use of organic amine reagents has a pungent odor and is not friendly to humans and the environment. In Patent CN101385980A, an organosilane is used as the precursor of the carrier and manganese is used as the active additive. After mixing copper salt, manganese salt and organosilane first, they are dissolved in an alcohol-water solvent, and then a sol-gel is formed by heating and stirring to obtain a copper-based binary catalyst, which has low-temperature hydrogenation catalytic activity. In Patent CN 106111155A, a catalyst containing one or several of the active main components Cu and the active additives Zn, Zr, Mn, La, P, Mo, Ni supported on silica is prepared by co-precipitation of a basic precipitant and a metal ion mixture, which can meet the requirements of high activity and selectivity. Summary of the Invention

[0005] Aiming at the problems of the existing catalyst having a small specific surface area, low activity, and easy removal of the hydroxyl group in methyl 3-hydroxypropionate, resulting in low selectivity of 1,3-propanediol, the present invention provides a composite catalyst for the hydrogenation of methyl 3-hydroxypropionate to 1,3-propanediol and a preparation method thereof.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A composite catalyst for the hydrogenation of methyl 3-hydroxypropionate to 1,3-propanediol, which comprises the following components:

[0008] (a) The main component CuO;

[0009] (b) The electronic additive barium strontium titanate;

[0010] (c) The hydrogenation active additive;

[0011] (d) The carrier and pore-expanding agent SiO2;

[0012] The hydrogenation active additive is one or more of NiO, MnO2, and MoO3.

[0013] Furthermore, based on the sum of weight percentages being 100%, the content of each component is: the main component 30-70%, the electronic additive 0.5-10%, the hydrogenation active additive 1.0-15%, and SiO2 10-35%.

[0014] The preparation method of the composite catalyst for the hydrogenation of methyl 3-hydroxypropionate to 1,3-propanediol comprises the following steps:

[0015] (1) Using tetrabutyl titanate, strontium nitrate and barium nitrate as raw materials, dissolving them together in absolute ethanol, and forming a barium strontium titanate sol by high-speed stirring. Then adding ethylene glycol, continuing high-speed stirring, and allowing the mixed sol to stand at room temperature for 12 hours to gelate it, obtaining a barium strontium titanate gel;

[0016] (2) Dissolving the CuO precursor and the hydrogenation activity promoter precursor according to the component ratio in an alcohol-water solution with a certain ratio, stirring and heating to 40-90 °C, then slowly dropping in an alcohol orthosilicate, and stirring and mixing evenly. The obtained gel is aged by stirring at 40-90 °C for 2-8 hours;

[0017] (3) Adding the barium strontium titanate gel prepared in step (1) to the gel aged in step (2) according to the ratio, strongly stirring and mixing for 6 hours, and then standing and aging for 12 hours;

[0018] (4) Drying the mixed gel obtained in step (3) at 80-150 °C for 4-40 hours, and then calcining it at 300-750 °C for 4-24 hours to obtain the composite catalyst.

[0019] Further, in step (1), the dosages of tetrabutyl titanate, strontium nitrate and barium nitrate are converted according to the molar ratio of titanium, strontium and barium elements being 1:0.7:0.3.

[0020] Further, in step (1), the dosage of ethylene glycol is 2-6 times the total molar amount of titanium, strontium and barium elements.

[0021] Further, in step (1), the rotation speed of the high-speed stirring is 300-600 r / min, the time of the first high-speed stirring is 4-8 hours, and the time of high-speed stirring after adding ethylene glycol is 12-48 hours.

[0022] Further, in step (2), the CuO precursor is one or more of copper nitrate, copper sulfate, copper acetate, copper chloride, preferably copper nitrate.

[0023] Further, in step (2), the hydrogenation activity promoter precursor is one or more of soluble salts such as nitrates, hydrochlorides, acetates, ammonium salts of Ni, Mn, Mo, preferably nickel nitrate, manganese nitrate, ammonium molybdate.

[0024] Further, in step (2), the alcohol-water solution is a mixture of one or more of monohydric alcohols, polyhydric alcohols and water, preferably an ethylene glycol aqueous solution; the alcohol concentration of the alcohol-water solution is 30-70 vol%.

[0025] Further, the orthosilicate alcohol ester described in step (2) is specifically tetraethyl orthosilicate or tetramethyl orthosilicate, preferably tetraethyl orthosilicate.

[0026] Further, the rotation speed of the strong stirring in step (3) is 400 r / min.

[0027] Further, the drying in step (4) is vacuum drying or atmospheric drying.

[0028] Further, the atmosphere for roasting in step (4) is air.

[0029] The obtained composite catalyst can be used for the hydrogenation of methyl 3-hydroxypropionate to 1,3-propanediol.

[0030] The remarkable advantages of the present invention are as follows:

[0031] In the present invention, the main catalyst CuO, the electronic promoter, the hydrogenation promoter and SiO2 are prepared into a composite catalyst with a large specific surface area by the sol-gel method. The hydrogenation promoters NiO, MnO2, and MoO3 are used to reduce the reduction temperature of CuO and improve the reduction degree, thereby improving the ability of the catalyst to activate hydrogen. The high dielectric constant material barium strontium titanate is used as the electronic promoter to promote the formation of suitable Cu 0 / Cu + active sites to enhance the adsorption of the ester group in methyl 3-hydroxypropionate, thereby improving the selectivity of 1,3-propanediol. Specific Embodiments

[0032] A composite catalyst for the hydrogenation of methyl 3-hydroxypropionate to 1,3-propanediol, based on the sum of weight percentages being 100%, includes: 30-70% of the main component CuO, 0.5-10% of the electronic promoter barium strontium titanate, 1.0-15% of one or more of the hydrogenation active promoters NiO, MnO2, and MoO3, and 10-35% of the carrier and pore expander SiO2.

[0033] The preparation method of the composite catalyst for the hydrogenation of methyl 3-hydroxypropionate to 1,3-propanediol includes the following steps:

[0034] (1) Weigh tetrabutyl titanate, strontium nitrate and barium nitrate according to the molar ratio of titanium, strontium and barium elements of 1:0.7:0.3, dissolve them together in anhydrous ethanol, and stir at a high speed of 300-600 r / min for 4-8 hours to form a barium strontium titanate sol. Then add ethylene glycol with a total molar amount of 2-6 times that of titanium, strontium and barium elements, continue to stir at a high speed of 300-600 r / min for 12-48 hours, and then let the mixed sol stand at room temperature for 12 hours to gelate it, obtaining a barium strontium titanate gel;

[0035] (2) Dissolve the CuO precursor and the hydrogenation activity promoter precursor according to the component ratio in an alcohol-water solution with a concentration of 30 - 70 vol%, stir and heat to 40 - 90 °C, then slowly dropwise add tetraethyl orthosilicate. After stirring and mixing evenly, the obtained gel is stirred and aged at 40 - 90 °C for 2 - 8 hours;

[0036] (3) Add the barium strontium titanate gel prepared in step (1) to the gel aged in step (2) according to the ratio. After strongly stirring and mixing at 400 r / min for 6 hours, let it stand and age for 12 hours;

[0037] (4) Dry the mixed gel obtained in step (3) at 80 - 150 °C for 4 - 40 hours, and then calcine it at 300 - 750 °C for 4 - 24 hours to obtain the composite catalyst.

[0038] Among them, the CuO precursor in step (2) is one or more of copper nitrate, copper sulfate, copper acetate, and copper chloride. The hydrogenation activity promoter precursor is one or more of soluble salts such as nitrates, hydrochlorides, acetates, and ammonium salts of Ni, Mn, and Mo. The alcohol-water solution is a mixture of one or more of monohydric alcohols and polyhydric alcohols and water.

[0039] To make the content of the present invention easier to understand, the technical solutions of the present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited thereto.

[0040] Example 140CuO - 2Ba 0.3 Sr 0.7 TiO3 - 5NiO - 53SiO2

[0041] (1) Preparation of Ba 0.3 Sr 0.7 TiO3 gel:

[0042] Weigh 0.34 g of tetrabutyl titanate, 0.15 g of strontium nitrate, and 0.078 g of barium nitrate as raw materials, dissolve them in 10 ml of absolute ethanol, and stir at high speed at 400 r / min for 6 hours to form a barium strontium titanate sol. Then add 0.25 g of ethylene glycol, continue to stir at high speed at 400 r / min for 24 hours, and then let the mixed sol stand at room temperature for 12 hours to gel it, obtaining the barium strontium titanate gel for standby.

[0043] (2) Preparation of Cu - Ni - TEOS gel

[0044] Measure 50 ml each of ethylene glycol and deionized water, and prepare an alcohol-water solution; weigh 12.2 g of copper nitrate trihydrate and 1.94 g of nickel nitrate hexahydrate and add them to the above alcohol-water solution. Stir well at room temperature for 2 hours, then transfer to a 70 °C water bath and continue stirring for 6 hours. Then slowly add 18.4 g of tetraethyl orthosilicate (TEOS), and after stirring and mixing evenly, the resulting gel is stirred and aged at 70 °C for 6 hours to obtain a Cu-Ni-TEOS gel;

[0045] (3) Preparation of Cu-based catalyst

[0046] Add the prepared barium strontium titanate gel to the Cu-Ni-TEOS gel. After vigorously stirring and mixing at 400 r / min for 6 hours, let it stand and age for 12 hours to obtain a uniform gel; then dry it at a constant temperature of 120 °C and normal pressure in an oven for 16 hours, and then calcine it in an air atmosphere at 550 °C for 6 hours to prepare a catalyst, denoted as 40CuO-2Ba 0.3 Sr 0.7 TiO3-5NiO-53SiO2, grind it and granulate it into granular catalysts with a mesh size of 20-40.

[0047] Comparative Example 1 40CuO-5NiO-55SiO2

[0048] Measure 50 ml each of ethylene glycol and deionized water, and prepare an alcohol-water solution; weigh 12.2 g of copper nitrate trihydrate and 1.94 g of nickel nitrate hexahydrate and add them to the above alcohol-water solution. Stir well at room temperature for 2 hours, then transfer to a 70 °C water bath and continue stirring for 6 hours. Then slowly add 19.07 g of tetraethyl orthosilicate (TEOS), maintain stirring and aging at 70 °C for 6 hours, and then let it stand and age for 24 h until it forms a gel; then dry it at a constant temperature of 120 °C and normal pressure in an oven for 16 hours, and then calcine it in an air atmosphere at 550 °C for 6 hours to prepare a catalyst, denoted as 40CuO-5NiO-55SiO2, grind it and granulate it into granular catalysts with a mesh size of 20-40.

[0049] Comparative Example 2 40CuO-2Ba 0.3 Sr 0.7 TiO3-58SiO2

[0050] (1) Ba 0.3 Sr 0.7 Preparation of Ba

[0051] Weigh 0.34 g of tetrabutyl titanate, 0.15 g of strontium nitrate and 0.078 g of barium nitrate as raw materials, dissolve them in 10 ml of absolute ethanol, and stir at a high speed of 400 r / min for 6 hours to form a barium strontium titanate sol. Then add 0.25 g of ethylene glycol and continue to stir at a high speed of 400 r / min for 24 hours. After that, let the mixed sol stand at room temperature for 12 hours to gelate it, and obtain the barium strontium titanate gel for standby.

[0052] (2)Preparation of Cu-TEOS gel

[0053] Measure 50 ml each of ethylene glycol and deionized water to prepare an alcohol-water solution; weigh 12.2 g of copper nitrate trihydrate and add it to the above alcohol-water solution. Stir well at room temperature for 2 hours, then transfer it to a water bath at 70 °C and continue to stir for 6 hours. Then slowly add 20.1 g of tetraethyl orthosilicate (TEOS), and stir and mix well. The obtained gel is stirred and aged at 70 °C for 6 hours to obtain a Cu-TEOS gel;

[0054] (3)Preparation of Cu-based catalyst

[0055] Add the prepared barium strontium titanate gel to the Cu-TEOS gel, and stir and mix strongly at a speed of 400 r / min for 6 hours, then stand and age for 12 hours to obtain a uniform gel; then dry it at a constant temperature of 120 °C and normal pressure in an oven for 16 hours, and then calcine it in an air atmosphere at 550 °C for 6 hours to prepare a catalyst, denoted as 40CuO-2Ba 0.3 Sr 0.7 TiO3-58SiO2, grind it and granulate it into granular catalysts with a particle size of 20-40 mesh.

[0056] Comparative Example 340CuO-2Ba 0.3 Sr 0.7 TiO3-5NiO-53SiO2-DP

[0057] (1)Preparation of Ba 0.3 Sr 0.7 TiO3

[0058] Dry the barium strontium titanate gel prepared in Example 1 in an oven at 120 °C for 5 hours, and then calcine it at 550 °C for 6 hours to obtain Ba 0.3 Sr 0.7 TiO3 powder.

[0059] (2)Preparation of catalyst by precipitation method

[0060] Weigh 12.2 g of copper nitrate trihydrate and 1.94 g of nickel nitrate hexahydrate, dissolve them in 50 ml of deionized water, stir for 30 minutes until a transparent solution is formed, then add the above-mentioned barium strontium titanate powder to this solution, stir well for 4 hours, and then slowly dropwise add 18.4 g of silica sol. After stirring well for 1 hour, transfer it to a 70 °C water bath and stir for another 2 hours. Prepare 100 ml of 0.5 mol / l sodium hydroxide solution, slowly dropwise add it to the above-mentioned metal salt suspension, and age the precipitate in a 70 °C water bath for 4 hours. Filter and wash the above-mentioned precipitate until the filtrate is neutral, dry it in an oven at 120 °C for 5 hours, and calcine it at 550 °C for 6 hours to obtain the catalyst prepared by the precipitation method, denoted as 40CuO-2Ba 0.3 Sr 0.7 TiO3-5NiO-53SiO2-DP, after grinding it, compacting it into a shape, crushing and sieving it into 20-40 mesh granular catalyst.

[0061] Comparative Example 4 40CuO-2Ba 0.3 Sr 0.7 TiO3-5BaO-53SiO2

[0062] Measure 50 ml each of ethylene glycol and deionized water and prepare an alcohol-water solution; weigh 12.2 g of copper nitrate trihydrate and 0.293 g of barium nitrate, add them to the above-mentioned alcohol-water solution, stir well at room temperature for 2 hours, then transfer it to a 70 °C water bath and continue to stir for 6 hours. Then slowly dropwise add 18.4 g of tetraethyl orthosilicate (TEOS), and stir and mix well. The resulting gel is aged by stirring at 70 °C for 6 hours to obtain a Cu-Ba-TEOS gel;

[0063] Add the barium strontium titanate gel prepared in Example 1 to the prepared Cu-Ba-TEOS gel, stir and mix strongly at 400 r / min for 6 hours, then stand and age for 12 hours to obtain a uniform gel-like state; then dry it at a constant temperature of 120 °C and normal pressure in an oven for 16 hours, and then calcine it in an air atmosphere at 550 °C for 6 hours to prepare a catalyst, denoted as 40CuO-2Ba 0.3 Sr 0.7 TiO3-5BaO-53SiO2, grind it and granulate it into 20-40 mesh granular catalyst.

[0064] Comparative Example 5 40CuO-2Ba 0.3 Sr 0.7 TiO-5MgO-53SiO2

[0065] Measure 50 ml each of ethylene glycol and deionized water, and prepare an alcohol-aqueous solution; weigh 12.2 g of copper nitrate trihydrate and 0.136 g of magnesium nitrate, and add them to the above alcohol-aqueous solution. Stir well at room temperature for 2 hours, then transfer to a 70 °C water bath and continue stirring for 6 hours. Slowly add 18.4 g of tetraethyl orthosilicate (TEOS). After stirring and mixing evenly, the resulting gel is stirred and aged at 70 °C for 6 hours to obtain a Cu-Mg-TEOS gel;

[0066] Add the barium strontium titanate gel prepared in Example 1 to the Cu-Mg-TEOS gel prepared in Example 1. After vigorously stirring and mixing at 400 r / min for 6 hours, let it stand and age for 12 hours to obtain a uniform gel-like substance; then dry it at a constant temperature of 120 °C under normal pressure in an oven for 16 hours, and then calcine it in an air atmosphere at 550 °C for 6 hours to prepare a catalyst, denoted as 40CuO-2Ba 0.3 Sr 0.7 TiO-5MgO-53SiO2, grind it and granulate it into a granular catalyst with a particle size of 20-40 mesh.

[0067] Comparative Example 6: 40CuO-2SrO-5NiO-53SiO2

[0068] Measure 50 ml each of ethylene glycol and deionized water, and prepare an alcohol-aqueous solution; weigh 12.2 g of copper nitrate trihydrate, 1.94 g of nickel nitrate hexahydrate and 0.41 g of strontium nitrate, and add them to the above alcohol-aqueous solution. Stir well at room temperature for 2 hours, then transfer to a 70 °C water bath and continue stirring for 6 hours. Slowly add 18.4 g of tetraethyl orthosilicate (TEOS). After stirring and mixing evenly, the resulting gel is stirred and aged at 70 °C for 6 hours, and then let it stand and age for 12 hours to obtain a uniform gel-like substance; then dry it at a constant temperature of 120 °C under normal pressure in an oven for 16 hours, and then calcine it in an air atmosphere at 550 °C for 6 hours to prepare a catalyst, denoted as 40CuO-2SrO-5NiO-53SiO2, grind it and granulate it into a granular catalyst with a particle size of 20-40 mesh.

[0069] Comparative Example 7: 40CuO-2BaO-5NiO-53SiO2

[0070] Measure 50 ml each of ethylene glycol and deionized water, and prepare an alcohol - aqueous solution; weigh 12.2 g of copper nitrate trihydrate, 1.94 g of nickel nitrate hexahydrate, and 0.34 g of barium nitrate, add them to the above - mentioned alcohol - aqueous solution, stir well at room temperature for 2 hours, then transfer to a 70 °C water bath and continue stirring for 6 hours, slowly add 18.4 g of tetraethyl orthosilicate (TEOS), after stirring and mixing evenly, the obtained gel is stirred and aged at 70 °C for 6 hours, and then statically aged for 12 hours to obtain a uniform gel; then dry it at a constant temperature of 120 °C under normal pressure in an oven for 16 hours, and then calcine it in an air atmosphere at 550 °C for 6 hours to prepare a catalyst, denoted as 40CuO - 2BaO - 5NiO - 53SiO2, grind it, and granulate it into granular catalysts with a particle size of 20 - 40 mesh.

[0071] Example 2 40CuO - 2Ba 0.3 Sr 0.7 TiO3 - 5MnO2 - 53SiO2

[0072] (1) Preparation of Ba 0.3 Sr 0.7 TiO3 gel:

[0073] Weigh 0.34 g of tetrabutyl titanate, 0.15 g of strontium nitrate, and 0.078 g of barium nitrate as raw materials, dissolve them in 10 ml of absolute ethanol, stir at a high speed of 400 r / min for 6 hours to form a barium strontium titanate sol, then add 0.25 g of ethylene glycol, continue to stir at a high speed of 400 r / min for 24 hours, and then let the mixed sol stand at room temperature for 12 hours to gel it, obtaining a barium strontium titanate gel for standby.

[0074] (2) Preparation of Cu - Mn - TEOS gel

[0075] Measure 50 ml each of ethylene glycol and deionized water, and prepare an alcohol - aqueous solution; weigh 12.2 g of copper nitrate trihydrate, 2.06 g of manganese nitrate (50%) and add them to the above - mentioned alcohol - aqueous solution, stir well at room temperature for 2 hours, then transfer to a 70 °C water bath and continue stirring for 6 hours, then slowly add 18.4 g of tetraethyl orthosilicate (TEOS), after stirring and mixing evenly, the obtained gel is stirred and aged at 70 °C for 6 hours to obtain a Cu - Mn - TEOS gel;

[0076] (3) Preparation of Cu - based catalyst

[0077] Add the prepared barium strontium titanate gel to the Cu - Ni - TEOS gel, stir - mix strongly at 400 r / min for 6 hours, then stand and age for 12 hours to obtain a uniform gel; then dry it at a constant temperature of 120 °C under normal pressure in an oven for 16 hours, and then calcine it in an air atmosphere at 550 °C for 6 hours to prepare a catalyst, denoted as 40CuO - 2Ba 0.3 Sr0.7 TiO3 - 5MnO2 - 53SiO2, grind it and granulate it into granular catalysts with a mesh size of 20 - 40.

[0078] Example 3: 40CuO - 2Ba 0.3 Sr 0.7 TiO3 - 5MoO3 - 53SiO2

[0079] (1) Ba 0.3 Sr 0.7 Preparation of BaSrTiO3 gel:

[0080] Weigh 0.34 g of tetrabutyl titanate, 0.15 g of strontium nitrate and 0.078 g of barium nitrate as raw materials, dissolve them in 10 ml of absolute ethanol, and stir at a high speed of 400 r / min for 6 hours to form a barium strontium titanate sol. Then add 0.25 g of ethylene glycol and continue to stir at a high speed of 400 r / min for 24 hours. After that, let the mixed sol stand at room temperature for 12 hours to gel it, and obtain the barium strontium titanate gel for standby.

[0081] (2) Preparation of Cu - Mo - TEOS gel

[0082] Measure 50 ml each of ethylene glycol and deionized water to prepare an alcohol - water solution; weigh 12.2 g of copper nitrate trihydrate and 0.68 g of ammonium molybdate, add them to the above - mentioned alcohol - water solution, stir well at room temperature for 2 hours, then transfer it to a water bath at 70 °C and continue to stir for 6 hours. Then slowly add 18.4 g of tetraethyl orthosilicate (TEOS), and stir and mix well. The obtained gel is stirred and aged at 70 °C for 6 hours to obtain the Cu - Mo - TEOS gel;

[0083] (3) Preparation of Cu - based catalyst

[0084] Add the prepared barium strontium titanate gel to the Cu - Ni - TEOS gel, stir and mix strongly at 400 r / min for 6 hours, then stand and age for 12 hours to obtain a uniform gel; then dry it at a constant temperature of 120 °C and normal pressure in an oven for 16 hours, and then calcine it in an air atmosphere at 550 °C for 6 hours to prepare the catalyst, denoted as 40CuO - 2Ba 0.3 Sr 0.7 TiO3 - 5MoO3 - 50SiO2, grind it and granulate it into granular catalysts with a mesh size of 20 - 40.

[0085] Example 4: 50CuO - 2Ba 0.3 Sr 0.7 TiO3 - 5NiO - 43SiO2

[0086] (1) Ba 0.3 Sr 0.7 Preparation of BaSrTiO3 gel:

[0087] Weigh 0.34 g of tetrabutyl titanate, 0.15 g of strontium nitrate and 0.078 g of barium nitrate as raw materials, dissolve them in 10 ml of absolute ethanol, and stir at a high speed of 400 r / min for 6 hours to form a barium strontium titanate sol. Then add 0.25 g of ethylene glycol, continue to stir at a high speed of 400 r / min for 24 hours, and then let the mixed sol stand at room temperature for 12 hours to gel it, obtaining a barium strontium titanate gel for standby.

[0088] (2) Preparation of Cu-Ni-TEOS gel

[0089] Measure 50 ml each of ethylene glycol and deionized water and prepare an alcohol-water solution; weigh 15.2 g of copper nitrate trihydrate and 1.94 g of nickel nitrate hexahydrate and add them to the above alcohol-water solution. Stir well at room temperature for 2 hours, then transfer to a water bath at 70 °C and continue to stir for 6 hours. Then slowly add 14.9 g of tetraethyl orthosilicate (TEOS), and after stirring and mixing evenly, the obtained gel is aged by stirring at 70 °C for 6 hours to obtain a Cu-Ni-TEOS gel;

[0090] (3) Preparation of Cu-based catalyst

[0091] Add the prepared barium strontium titanate gel to the Cu-Ni-TEOS gel, stir and mix strongly at 400 r / min for 6 hours, and then stand and age for 12 hours to obtain a uniform gel; then dry it at a constant temperature of 120 °C and normal pressure in an oven for 16 hours, and then calcine it in an air atmosphere at 550 °C for 6 hours to prepare a catalyst, denoted as 50CuO-2Ba 0.3 Sr 0.7 TiO3-5NiO-43SiO2, grind it and granulate it into granular catalysts with a mesh size of 20-40.

[0092] Example 5 35CuO-2Ba 0.3 Sr 0.7 TiO3-5NiO-58SiO2

[0093] (1) Ba 0.3 Sr 0.7 Preparation of TiO3 gel:

[0094] Weigh 0.34 g of tetrabutyl titanate, 0.15 g of strontium nitrate and 0.078 g of barium nitrate as raw materials, dissolve them in 10 ml of absolute ethanol, and stir at a high speed of 400 r / min for 6 hours to form a barium strontium titanate sol. Then add 0.25 g of ethylene glycol, continue to stir at a high speed of 400 r / min for 24 hours, and then let the mixed sol stand at room temperature for 12 hours to gel it, obtaining a barium strontium titanate gel for standby.

[0095] (2) Preparation of Cu-Ni-TEOS Gel

[0096] Measure 50 ml each of ethylene glycol and deionized water and prepare an alcohol-water solution; weigh 10.6 g of copper nitrate trihydrate and 1.94 g of nickel nitrate hexahydrate and add them to the above alcohol-water solution. Stir well at room temperature for 2 hours, then transfer to a 70 °C water bath and continue stirring for 6 hours. Then slowly add 20.1 g of tetraethyl orthosilicate (TEOS), and after stirring and mixing evenly, the resulting gel is stirred and aged at 70 °C for 6 hours to obtain a Cu-Ni-TEOS gel;

[0097] (3) Preparation of Cu-based Catalyst

[0098] Add the prepared barium strontium titanate gel to the Cu-Ni-TEOS gel. After vigorously stirring and mixing at 400 r / min for 6 hours, let it stand and age for 12 hours to obtain a uniform gel; then dry it at a constant temperature of 120 °C and normal pressure in an oven for 16 hours, and then calcine it in an air atmosphere at 550 °C for 6 hours to prepare a catalyst, denoted as 35CuO-2Ba 0.3 Sr 0.7 TiO3-5NiO-58SiO2, and grind it and granulate it into granular catalysts with a particle size of 20-40 mesh.

[0099] Catalyst Evaluation

[0100] Using a methanol solution of methyl 3-hydroxypropionate as the reactant, evaluate the performance of the prepared catalyst on a high-pressure fixed-bed reactor. The catalyst loading is 20.0 ml. Before feeding, the catalyst is reduced with hydrogen to make the active components exist in the form of elemental substances. The reduction conditions are: temperature 320 °C, pressure 6.0 MPa, hydrogen flow rate 100 ml / min, and time 5 h. During the reaction, methyl 3-hydroxypropionate is diluted with methanol to a mass concentration of 10%, the reaction temperature is 160 °C, the reaction pressure is 6 MPa, and the space velocity of the raw material is 0.3 h -1 , and the hydrogen-ester molar ratio is 27.

[0101] After the reaction temperature is stable for 5 h, collect the products in the condenser behind the reactor, and use a GC-MC combined instrument to qualitatively and quantitatively analyze the raw materials and the products after hydrogenation, and calculate the conversion rate of the hydrogenation reaction of methyl 3-hydroxypropionate and the selectivity of 1,3-propanediol. The calculation formulas are as follows, and the results are shown in Table 1:

[0102]

[0103] .

[0104] Table 1

[0105]

[0106] From the comparison between Example 1 and Comparative Example 1 in Table 1, it can be seen that the catalyst with barium strontium titanate added as an electronic promoter has higher hydrogenation conversion rate of methyl 3-hydroxypropionate and higher selectivity for 1,3-propanediol. This is because barium strontium titanate has a perovskite structure, which can effectively separate holes and electrons, contribute to electron conduction, and is more conducive to the dispersion of active sites and the adsorption of reaction molecules.

[0107] From the comparison between Example 1 and Comparative Example 3, it can be seen that compared with the deposition-precipitation method, the catalyst prepared by the sol-gel method has a larger specific surface area, which is more conducive to the dispersion of active sites and the adsorption of reaction molecules. Therefore, the hydrogenation conversion rate of methyl 3-hydroxypropionate and the selectivity for 1,3-propanediol are both higher.

[0108] From the comparison between Example 1 and Comparative Examples 4 and 5, it can be seen that if NiO is replaced by MgO or BaO, the formed catalyst does not have good catalytic performance, which proves that there are specific interactions among the components in the obtained CuO-Ba 0.3 Sr 0.7 TiO3-NiO-SiO2 catalyst.

[0109] From the comparison between Example 1 and Comparative Examples 6 and 7, it can be seen that when the electronic promoter barium strontium titanate is replaced by oxides BaO and SrO, the selectivity for 1,3-propanediol is low due to the inability to achieve electron conduction.

[0110] From the comparison between Examples 1 - 3 and Comparative Example 2, it can be seen that the incorporation of Ni, Mn, and Mo can improve the ability of the catalyst to activate hydrogen by promoting the reduction of copper oxide, thereby enhancing the catalyst activity.

[0111] The comparison between Example 1 and Examples 4 and 5 further proves that there is a high interaction among CuO, barium strontium titanate, and the hydrogenation promoter in the catalyst. Different ratios of the three components will directly affect the conversion rate of methyl 3-hydroxypropionate and the selectivity for 1,3-propanediol. Among them, 40CuO-2Ba 0.3 Sr 0.7 TiO3-5NiO-53SiO2 has the best catalytic effect.

[0112] The above are only the preferred embodiments of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims

1. A composite catalyst for the hydrogenation of methyl 3-hydroxypropionate to 1,3-propanediol, characterized in that, It includes the following components: (a)The main component CuO; (b)The electronic promoter barium strontium titanate; (c)The hydrogenation activity promoter; (d)The carrier and pore-expanding agent SiO2; The hydrogenation activity promoter is one or more of NiO, MnO2, and MoO3; The preparation of the composite catalyst includes the following steps: (1)Using tetrabutyl titanate, strontium nitrate, and barium nitrate as raw materials, dissolving them together in absolute ethanol, and vigorously stirring to form a barium strontium titanate sol. Then add ethylene glycol, continue to stir vigorously, and let the mixed sol stand at room temperature for 12 hours to gel it, obtaining barium strontium titanate gel; (2)Dissolve the CuO precursor and the hydrogenation activity promoter precursor according to the component ratio in an alcohol-water solution, stir and heat to 40 - 90 °C, then slowly dropwise add the alkoxysilane, and after stirring and mixing evenly, the obtained gel is aged by stirring at 40 - 90 °C for 2 - 8 hours; (3)Add the barium strontium titanate gel prepared in step (1) to the gel aged in step (2) according to the ratio, strongly stir and mix for 6 hours, and then stand and age for 12 hours; (4)Dry the mixed gel obtained in step (3) at 80 - 150 °C for 4 - 40 hours, and then calcine it at 300 - 750 °C for 4 - 24 hours to obtain the composite catalyst.

2. The composite catalyst according to claim 1, characterized in that, Calculated based on the sum of weight percentages being 100%, the contents of each component are: the main component 30 - 70%, the electronic promoter 0.5 - 10%, the hydrogenation activity promoter 1.0 - 15%, and SiO2 10 - 35%.

3. The composite catalyst according to claim 1, wherein In step (1), the dosages of tetrabutyl titanate, strontium nitrate, and barium nitrate are converted according to the molar ratio of the three elements of titanium, strontium, and barium being 1:0.7:0.3; the dosage of ethylene glycol is 2 - 6 times the total molar amount of the three elements of titanium, strontium, and barium.

4. The composite catalyst according to claim 1, wherein In step (1), the rotation speed of the vigorous stirring is 300 - 600 r / min, the time of the first vigorous stirring is 4 - 8 hours, and the time of vigorous stirring after adding ethylene glycol is 12 - 48 hours.

5. The composite catalyst according to claim 1, characterized in that, In step (2), the CuO precursor is one or more of copper nitrate, copper sulfate, copper acetate, and copper chloride; The hydrogenation activity promoter precursor is one or more of the nitrates, hydrochlorides, acetates, and ammonium salts of Ni, Mn, and Mo.

6. The composite catalyst according to claim 1, characterized in that, In step (2), the alcohol-water solution is a mixture of one or more of monohydric alcohols and polyhydric alcohols and water, and its alcohol concentration is 30 - 70 vol%.

7. The composite catalyst according to claim 1, wherein The alkoxysilane in step (2) is specifically ethyl orthosilicate or methyl orthosilicate.

8. The composite catalyst according to claim 1, wherein The rotation speed of the strong stirring in step (3) is 400 r / min.

9. Application of a composite catalyst as described in claim 1 in the hydrogenation of methyl 3 - hydroxypropionate to 1,3 - propanediol.

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