A composite catalyst for hydrogenating methyl 3-hydroxypropionate to 1,3-propylene glycol and its preparation method

Abstract

The present invention discloses a composite catalyst for hydrogenating 3-hydroxypropionate to 1,3-propylene glycol and a preparation method thereof. The catalyst is prepared by a sol-gel method and comprises the following components: (a) a main component CuO; (b) an electronic auxiliary agent of any one of Nb3Sn, Nb3Ge, and Nb3Al; and (c) a carrier and a pore-enlarging agent SiO2. The present invention promotes the formation of Cu species into Cu by adding electronic auxiliary agents Nb3Sn, Nb3Ge, and Nb3Al with superconducting properties to the copper-based catalyst. 0 / Cu + The active site is increased, and the adsorption of the ester group in methyl 3-hydroxypropionate on the catalyst surface is improved, thereby improving the selectivity of 1,3-propylene glycol, solving the problem of low catalyst activity in existing catalysts and low selectivity of the main product 1,3-propylene glycol due to higher β-OH hydrogenation activity than ester group.

Description

Technical Field

[0001] The invention belongs to the field of catalyst preparation, and particularly relates to a composite catalyst for hydrogenating methyl 3-hydroxypropionate to produce 1,3-propylene glycol 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 the production of unsaturated polyesters, plasticizers, surfactants, emulsifiers, and demulsifiers, but its primary application is as a polymer monomer, used with terephthalic acid (PTA) to synthesize PTT (polytrimethylene terephthalate) fibers. Compared to fibers like PET, PBT, and PA6, PTT offers superior resilience and dyeability, enabling the development of personalized fashion fabrics that are comfortable, stretchable, colorful, and have diverse weaves.

[0003] The hydromethylation of ethylene oxide to produce the intermediate product, methyl 3-hydroxypropionate, followed by catalytic hydrogenation to produce 1,3-PDO, is the only way to achieve the large-scale production of inexpensive 1,3-PDO. This method has low raw material costs and is easily scaled up for large-scale production, providing an inexpensive raw material for the mass production of PTT fibers. In this method, the intermediate methyl 3-hydroxypropionate is hydrogenated to produce 1,3-propylene glycol. Because the β-hydroxy group in methyl 3-hydroxypropionate is more easily removed by hydrogenation than the ester group, it forms a more suitable active site for ester hydrogenation, significantly improving the selectivity of the main product, 1,3-propylene glycol.

[0004] Copper-based catalysts for the hydrogenation of methyl 3-hydroxypropionate have become a research hotspot due to their low production cost, high activity, high selectivity, mild reaction conditions, and good toxicity resistance when combined with other active agents. Patent CN 1911507A utilizes a method in which an organic amine is pre-complexed with a copper salt in an alcohol solvent, followed by the addition of a fatty alcohol orthosilicate and an aluminum fatty alcohol as a support precursor, followed by the addition of a gelling agent and heating to form a sol-gel. This method produces a low-loading copper-based single-component catalyst, effectively improving the catalyst's sintering resistance and service life. However, because the preparation process utilizes only copper as a single component, its catalytic activity remains to be improved. Furthermore, the use of an organic amine reagent produces a pungent odor, making it unfriendly to humans and the environment. Patent CN 101385980A reports a method using an organosilane as a support precursor and manganese as an active agent. The copper salt, manganese salt, and organosilane are mixed, dissolved in an alcohol-water solvent, and then heated and stirred to form a sol-gel. This copper-based binary catalyst exhibits low-temperature hydrogenation catalytic activity. Patent CN108187676A reports a copper-based catalyst for ester hydrogenation to diols and its preparation method and application. The catalyst is composed of Cu, C 60 Fullerene and carrier SiO2 composition, C 60and Cu are loaded on the surface of SiO2 carrier, C 60 Stable contact with Cu through C 60 The balance of the surface charge of active copper is achieved, and the activity of copper on the carrier surface is improved so that the copper-based catalyst can exert higher catalytic activity. Summary of the Invention

[0005] In response to the problems of low activity, numerous side reactions and low selectivity of 1,3-propylene glycol in existing catalysts, the present invention provides a composite catalyst for hydrogenating methyl 3-hydroxypropionate to produce 1,3-propylene glycol and a preparation method thereof.

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

[0007] A composite catalyst for hydrogenating methyl 3-hydroxypropionate to 1,3-propylene glycol, comprising the following components:

[0008] (a) Main component CuO;

[0009] (b) electronic auxiliaries;

[0010] (c) carrier and pore-enlarging agent SiO2;

[0011] The electronic auxiliary agent is any one of Nb3Sn, Nb3Ge, and Nb3Al.

[0012] Furthermore, in terms of weight percentage, the content of each component is: main component 45%, electronic auxiliary agent 0.05%, SiO2 54.95%, or main component 45%, electronic auxiliary agent 0.2%, SiO2 54.8%, or main component 45%, electronic auxiliary agent 0.6%, SiO2 54.4%.

[0013] The preparation method of the composite catalyst for hydrogenating 3-hydroxypropionate to 1,3-propylene glycol comprises the following steps:

[0014] (1) Disperse the copper salt and the electronic auxiliary agent in an alcohol-water solution, then stir and heat to 40-90°C, and slowly add an appropriate amount of orthosilicate according to the component ratio of SiO2;

[0015] (2) Stirring and aging the gel obtained in step (1) at 50-90°C for 2-12 hours, then aging the gel at room temperature for 12-36 hours, and then drying at 70-140°C for 4-48 hours;

[0016] (3) calcining the solid obtained in step (2) at 300-750° C. for 4-24 hours to obtain the composite catalyst.

[0017] Furthermore, the copper salt in step (1) is one or more of copper nitrate, copper sulfate, copper acetate, and copper chloride, preferably copper nitrate.

[0018] Furthermore, the alcohol-water solution in step (1) is a mixture of monohydric alcohol and / or polyhydric alcohol and water, preferably ethylene glycol, and its alcohol concentration is 40-80 vol%.

[0019] Furthermore, the orthosilicate alcohol ester in step (1) is ethyl orthosilicate or methyl orthosilicate, preferably ethyl orthosilicate.

[0020] Furthermore, the drying in step (2) is vacuum drying or normal pressure drying.

[0021] Furthermore, the calcination atmosphere in step (3) is air.

[0022] The obtained composite catalyst can be used for hydrogenation of methyl 3-hydroxypropionate to 1,3-propylene glycol. The specific operation is as follows: the catalyst loading amount is 20.0 ml. The catalyst is reduced with hydrogen before feeding so that the active component exists in the form of a single substance. The reduction conditions are: temperature 200-450 ° C, pressure 0.1-8.0 MPa, hydrogen flow rate 10-200 ml / min, time 0.5-36 h. During the reaction, methyl 3-hydroxypropionate is diluted with methanol to a mass concentration of 5-20%, temperature 140-200 ° C, pressure 3-8 MPa, and raw material space velocity 0.01-3.0 h -1 , hydrogen ester molar ratio 10-200.

[0023] The significant advantages of the present invention are:

[0024] The present invention adopts the sol-gel method to form a composite catalyst with the main catalyst CuO, one of the electronic auxiliary agents Nb3Sn, Nb3Ge, Nb3Al and SiO2. A small amount of Nb3Sn, Nb3Ge, Nb3Al with superconducting properties is used as the electronic auxiliary agent to promote the reaction of CuO. + / Cu 0 The generation of active sites enhances the adsorption of ester groups in methyl 3-hydroxypropionate, thereby improving the selectivity of 1,3-propylene glycol. DETAILED DESCRIPTION

[0025] A composite catalyst for hydrogenating methyl 3-hydroxypropionate to produce 1,3-propylene glycol comprises: 45% of a main component of CuO, 0.05%, 0.2% or 0.6% of an electronic auxiliary agent of any one of Nb3Sn, Nb3Ge and Nb3Al, and 54.4%, 54.8% or 54.95% of SiO2.

[0026] The preparation method of the composite catalyst for hydrogenating 3-hydroxypropionate to 1,3-propylene glycol comprises the following steps:

[0027] (1) Disperse the copper salt and the electronic auxiliary agent in an alcohol-water solution, then stir and heat to 40-90°C, and slowly add an appropriate amount of orthosilicate according to the component ratio of SiO2;

[0028] (2) Stirring and aging the gel obtained in step (1) at 50-90°C for 2-12 hours, then aging the gel at room temperature for 12-36 hours, and then drying at 70-140°C for 4-48 hours;

[0029] (3) calcining the solid obtained in step (2) at 300-750° C. for 4-24 hours to obtain the composite catalyst.

[0030] The copper salt in step (1) is one or more of copper nitrate, copper sulfate, copper acetate, and copper chloride. The alcohol-water solution is a mixture of monohydric alcohol and / or polyhydric alcohol and water, and the alcohol concentration is 40-80 vol%. The orthosilicate alcohol ester is ethyl orthosilicate or methyl orthosilicate.

[0031] In order to make the contents of the present invention easier to understand, the technical solutions of the present invention are further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.

[0032] Example 145CuO-0.2Nb3Al-54.8SiO2

[0033] 50 ml each of ethylene glycol and deionized water were weighed to prepare an alcohol-water solution. 27.34 g of copper nitrate trihydrate and 0.04 g of Nb3Al2O2 were weighed and added to the alcohol-water solution. The mixture was stirred thoroughly at room temperature for 2 hours, then transferred to a 70°C water bath and stirred for another 6 hours. Then, 48.20 g of tetraethyl orthosilicate (TEOS) was added dropwise to the solution. Stirring was continued at 70°C for 6 hours, followed by aging at room temperature for 24 hours until a gel formed. The solution was then dried in an oven at 120°C under atmospheric pressure for 16 hours and calcined at 550°C in air for 6 hours to obtain a catalyst designated as 45CuO-0.2Nb3Al-54.8SiO2. The resulting catalyst was compacted, crushed, and sieved into 20-40 mesh granules.

[0034] Comparative Example 145CuO-55SiO2

[0035] 50 ml each of ethylene glycol and deionized water were weighed to prepare an alcohol-water solution. 27.34 g of copper nitrate trihydrate was weighed and added to the alcohol-water solution. The solution was stirred thoroughly at room temperature for 2 hours, then transferred to a 70°C water bath and stirred for another 6 hours. Then, 48.38 g of tetraethyl orthosilicate (TEOS) was added dropwise to the solution. Stirring was continued at 70°C for 6 hours, followed by aging at room temperature for 24 hours until a gel formed. The solution was then dried in an oven at 120°C under atmospheric pressure for 16 hours and calcined at 550°C in air for 6 hours to obtain a catalyst designated as 45CuO-55SiO2. The resulting catalyst was compacted, crushed, and sieved into 20-40 mesh granules.

[0036] Comparative Example 20.2Nb3Al-99.8SiO2

[0037] 50 ml each of ethylene glycol and deionized water were measured to prepare an alcohol-water solution. 0.04 g of Nb3Al was weighed and added to the alcohol-water solution. The mixture was stirred thoroughly at room temperature for 2 hours, then transferred to a 70°C water bath and stirred for another 6 hours. 87.79 g of tetraethyl orthosilicate (TEOS) was then added dropwise to the solution. Stirring was continued at 70°C for 6 hours, followed by aging at room temperature for 24 hours until a gel formed. The solution was then dried in an oven at 120°C under atmospheric pressure for 16 hours and calcined at 550°C in air for 6 hours to obtain a catalyst, designated 0.2Nb3Al-99.8SiO2. The resulting catalyst was compacted and shaped, then crushed and sieved into 20-40 mesh granules.

[0038] Comparative Example 345CuO-0.2Nb2O5-54.8SiO2

[0039] 50 ml each of ethylene glycol and deionized water were weighed to prepare an alcohol-water solution. 27.34 g of copper nitrate trihydrate and 0.04 g of Nb2O5 were weighed and added to the alcohol-water solution. The mixture was stirred thoroughly at room temperature for 2 hours, then transferred to a 70°C water bath and stirred for another 6 hours. Then, 48.20 g of tetraethyl orthosilicate (TEOS) was added dropwise to the solution. Stirring was continued at 70°C for 6 hours, followed by aging at room temperature for 24 hours until a gel formed. The solution was then dried in an oven at 120°C under atmospheric pressure for 16 hours and calcined at 550°C in air for 6 hours to obtain a catalyst designated as 45CuO-0.2Nb2O5-54.8SiO2. The resulting catalyst was compacted and shaped, then crushed and sieved into 20-40 mesh granules.

[0040] Comparative Example 445CuO-0.2Al2O3-54.8SiO2

[0041] 50 ml each of ethylene glycol and deionized water were weighed to prepare an alcohol-water solution. 27.34 g of copper nitrate trihydrate and 0.04 g of Al₂O₃ were weighed and added to the alcohol-water solution. The mixture was stirred thoroughly at room temperature for 2 hours, then transferred to a 70°C water bath and stirred for a further 6 hours. Then, 48.20 g of tetraethyl orthosilicate (TEOS) was dropwise added to the solution. Stirring was continued at 70°C for 6 hours, followed by aging at room temperature for 24 hours until a gel formed. The solution was then dried in an oven at 120°C under atmospheric pressure for 16 hours and calcined at 550°C in air for 6 hours to obtain a catalyst designated as 45CuO-0.2Al₂O₃-54.8SiO₂. The resulting catalyst was compacted, crushed, and sieved into 20-40 mesh granules.

[0042] Comparative Example 545CuO-0.2Ga2O3-54.8SiO2

[0043] 50 ml each of ethylene glycol and deionized water were weighed to prepare an alcohol-water solution. 27.34 g of copper nitrate trihydrate and 0.04 g of Ga2O3 were weighed and added to the alcohol-water solution. The mixture was stirred thoroughly at room temperature for 2 hours, then transferred to a 70°C water bath and stirred for another 6 hours. Then, 48.20 g of tetraethyl orthosilicate (TEOS) was added dropwise to the solution. Stirring was continued at 70°C for 6 hours, followed by aging at room temperature for 24 hours until a gel formed. The solution was then dried in an oven at 120°C under atmospheric pressure for 16 hours and calcined at 550°C in air for 6 hours to obtain a catalyst designated 45CuO-0.2Ga2O3-54.8SiO2. The resulting catalyst was compacted and shaped, then crushed and sieved into 20-40 mesh granules.

[0044] Comparative Example 645CuO-0.2Nb3Al / 54.8SiO2-DP

[0045] 27.34 g of copper nitrate trihydrate was weighed and dissolved in 50 ml of deionized water. The mixture was stirred for 30 minutes until a clear solution was obtained. 0.04 g of Nb3Al powder was then added to the solution and stirred thoroughly for 4 hours. Then, 36.53 g of 30% silica sol was slowly added dropwise. After stirring for 1 hour, the mixture was transferred to a 70°C water bath and stirred for an additional 2 hours. 100 ml of 0.5 mol / L sodium hydroxide solution was prepared and slowly added dropwise to the suspension. The mixture was then aged in a 90°C water bath for 6 hours. The precipitate was filtered and washed until the residue was neutral, then dried in a 120°C oven for 10 hours. The resulting solid was calcined at 550°C for 6 hours to obtain the catalyst 45CuO-0.2Nb3Al / 54.8SiO2-DP. The resulting catalyst was compacted and shaped, then crushed and sieved into 20-40 mesh granules.

[0046] Example 245CuO-0.2Nb3Sn-54.8SiO2

[0047] 50 ml each of ethylene glycol and deionized water were weighed to prepare an alcohol-water solution. 27.34 g of copper nitrate trihydrate and 0.04 g of Nb3Sn were weighed and added to the alcohol-water solution. The mixture was stirred thoroughly at room temperature for 2 hours, then transferred to a 70°C water bath and stirred for another 6 hours. Then, 48.20 g of tetraethyl orthosilicate (TEOS) was dropwise added to the solution. Stirring was continued at 70°C for 6 hours, followed by aging at room temperature for 24 hours until a gel formed. The solution was then dried in an oven at 120°C under atmospheric pressure for 16 hours and calcined at 550°C in air for 6 hours to obtain a catalyst designated 45CuO-0.2Nb3Sn-54.8SiO2. The resulting catalyst was compacted and sieved into 20-40 mesh granules.

[0048] Example 345CuO-0.2Nb3Ge-54.8SiO2

[0049] 50 ml each of ethylene glycol and deionized water were weighed to prepare an alcohol-water solution. 27.34 g of copper nitrate trihydrate and 0.04 g of Nb3Ge were weighed and added to the alcohol-water solution. The mixture was stirred thoroughly at room temperature for 2 hours, then transferred to a 70°C water bath and stirred for another 6 hours. Then, 48.20 g of tetraethyl orthosilicate (TEOS) was added dropwise to the solution. Stirring was continued at 70°C for 6 hours, followed by aging at room temperature for 24 hours until a gel formed. The solution was then dried in an oven at 120°C under atmospheric pressure for 16 hours and calcined at 550°C in air for 6 hours to obtain a catalyst designated as 45CuO-0.2 Nb3Ge-54.8SiO2. The resulting catalyst was compacted and sieved into 20-40 mesh granules.

[0050] Example 445CuO-0.6Nb3Al-54.4SiO2

[0051] 50 ml each of ethylene glycol and deionized water were weighed to prepare an alcohol-water solution. 27.34 g of copper nitrate trihydrate and 0.12 g of Nb3Al2O2 were weighed and added to the alcohol-water solution. The mixture was stirred thoroughly at room temperature for 2 hours, then transferred to a 70°C water bath and stirred for another 6 hours. Then, 47.85 g of tetraethyl orthosilicate (TEOS) was added dropwise to the solution. Stirring was continued at 70°C for 6 hours, followed by aging at room temperature for 24 hours until a gel formed. The solution was then dried in an oven at 120°C under atmospheric pressure for 16 hours and calcined at 550°C in air for 6 hours to obtain a catalyst designated as 45CuO-0.6Nb3Al-54.4SiO2. The resulting catalyst was compacted, crushed, and sieved into 20-40 mesh granules.

[0052] Example 545CuO-0.05Nb3Al-54.95SiO2

[0053] 50 ml each of ethylene glycol and deionized water were weighed to prepare an alcohol-water solution. 27.34 g of copper nitrate trihydrate and 0.01 g of Nb3Al2O2 were weighed and added to the alcohol-water solution. The mixture was stirred thoroughly at room temperature for 2 hours, then transferred to a 70°C water bath and stirred for another 6 hours. Then, 48.34 g of tetraethyl orthosilicate (TEOS) was added dropwise to the solution. The mixture was stirred and aged at 70°C for 6 hours, followed by aging at room temperature for 24 hours until a gel formed. The solution was then dried in an oven at 120°C under atmospheric pressure for 16 hours and calcined at 550°C in air for 6 hours to obtain a catalyst designated as 45CuO-0.05Nb3Al-54.95SiO2. The resulting catalyst was compacted and shaped, then crushed and sieved into 20-40 mesh granules.

[0054] Catalyst evaluation

[0055] The performance of the prepared catalyst was evaluated in a high-pressure fixed-bed reactor using a methanol solution of methyl 3-hydroxypropionate as the reactant. The catalyst loading was 20.0 ml. The catalyst was reduced with hydrogen before feeding under the following reduction conditions: temperature 320°C, pressure 6 MPa, hydrogen flow rate 100 ml / min, and reaction time 5 h. The reaction conditions were: methyl 3-hydroxypropionate diluted with methanol to a mass concentration of 10%, temperature 160°C, pressure 6 MPa, and feed space velocity 0.3 h / min. -1 , hydrogen ester molar ratio 27.

[0056] After the reaction temperature stabilized for 5 hours, the product from the condensate tank after the reactor was collected. The raw materials and hydrogenated products were quantitatively and qualitatively analyzed using a GC-MC coupled instrument. The conversion rate of methyl 3-hydroxypropionate hydrogenation reaction and the selectivity of 1,3-propylene glycol were calculated. The calculation formula is as follows. The reaction results are shown in Table 1:

[0057] ,

[0058] .

[0059] Table 1

[0060]

[0061] As shown in Table 1, by comparing Examples 1-3 with Comparative Example 1, it can be seen that the superconducting material additives Nb3Sn, Nb3Ge, and Nb3Al have good electronic conductivity, and their addition can promote the reaction process of Cu + / Cu 0 The generation of active sites enhances the adsorption of ester groups in methyl 3-hydroxypropionate, thereby improving the selectivity of 1,3-propylene glycol.

[0062] By comparing Example 1 with Comparative Example 2, it can be seen that CuO is the main active phase, and Nb3Al as an additive does not directly improve the hydrogenation activity of methyl 3-hydroxypropionate.

[0063] By comparing Example 1 with Comparative Examples 3 and 4, it can be seen that using the related oxides Nb2O5 and Al2O3 that constitute Nb3Al as additives to react with CuO cannot better form 1,3-propylene glycol. This may be because Nb2O5 and Al2O3 have strong acidity and are more likely to form the by-product methyl propionate.

[0064] By comparing Example 1 with Comparative Example 6, it can be seen that compared with the precipitation method, the catalyst prepared by the sol-gel method has a more complete contact between the additive and CuO, and the active groups are easily exposed to the gas phase, which makes it easier to adsorb ester groups and improve the selectivity of 1,3-propylene glycol.

[0065] By comparing Example 1 with Examples 4 and 5, it can be seen that CuO and the electron auxiliary agent Nb3Al in the 3-hydroxypropionic acid methyl ester hydrogenation catalyst have a high interaction, and the ratio of the three components significantly affects the conversion rate of 3-hydroxypropionic acid methyl ester and the improvement of 1,3-propylene glycol selectivity, among which 45CuO-0.2Nb3Al-54.8SiO2 has the best catalytic effect.

[0066] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A composite catalyst for hydrogenating methyl 3-hydroxypropionate to 1,3-propylene glycol, characterized in that: Includes the following components: (a) Main component CuO; (b) electronic auxiliaries; (c) carrier and pore-enlarging agent SiO2; The electronic auxiliary agent is any one of Nb3Sn, Nb3Ge, and Nb3Al.

2. The composite catalyst according to claim 1, wherein Calculated by weight percentage, the content of each component is: main component 45%, electronic auxiliary agent 0.05%, SiO2 54.95%, or main component 45%, electronic auxiliary agent 0.2%, SiO2 54.8%, or main component 45%, electronic auxiliary agent 0.6%, SiO2 54.4%.

3. A method for preparing the composite catalyst according to claim 1, characterized in that: The steps include: (1) Disperse the copper salt and the electronic auxiliary agent in an alcohol-water solution, then stir and heat to 40-90°C, and slowly add an appropriate amount of orthosilicate; (2) Stirring and aging the gel obtained in step (1) at 50-90°C for 2-12 hours, then aging the gel at room temperature for 12-36 hours, and then drying at 70-140°C for 4-48 hours; (3) calcining the solid obtained in step (2) at 300-750° C. for 4-24 hours to obtain the composite catalyst.

4. The method for preparing the composite catalyst according to claim 3, wherein: The copper salt in step (1) is one or more of copper nitrate, copper sulfate, copper acetate and copper chloride.

5. The method for preparing the composite catalyst according to claim 3, wherein: The alcohol-water solution in step (1) is a mixture of monohydric alcohol and / or polyhydric alcohol and water, and its alcohol concentration is 40-80 vol%.

6. The method for preparing the composite catalyst according to claim 3, wherein: The orthosilicate alcohol ester in step (1) is ethyl orthosilicate or methyl orthosilicate.

7. Use of the composite catalyst as claimed in claim 1 in hydrogenating methyl 3-hydroxypropionate to produce 1,3-propylene glycol.

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