Preparation of Cu / ZnO / Al2O3 / ZrO2 catalyst and application of Cu / ZnO / Al2O3 / ZrO2 catalyst in fatty acid methyl ester hydrogenation reaction

Abstract

The invention relates to preparation of a Cu / ZnO / Al2O3 / ZrO2 catalyst and application of the Cu / ZnO / Al2O3 / ZrO2 catalyst in hydrogenation reaction of fatty acid methyl ester. According to the catalyst, copper serves as a metal-based active center, multiple non-noble metals are added for modification, the molar ratio of Cu to Zn to Al to Zr is regulated and controlled through a coprecipitation method, the calcination temperature is optimized, and the activity, selectivity and stability of the catalyst are remarkably improved. The catalyst shows excellent performance in fatty acid methyl ester hydrogenation reaction and shows high activity in methyl laurate (C12), methyl myristate (C14) and methyl palmitate (C16), the conversion rate of fatty acid methyl ester reaches 90% or above, and products are mainly corresponding fatty alcohol and alkane. The preparation method is simple in process, low in cost and suitable for industrial production.

Description

Technical Field

[0001] The present invention belongs to the field of catalyst technology, and specifically relates to the preparation of a Cu / ZnO / Al2O3 / ZrO2 catalyst and its application in the hydrogenation of fatty acid methyl esters, particularly the hydrogenation of methyl laurate, methyl myristate, and methyl palmitate. Background Art

[0002] With the deepening global focus on green chemistry and sustainable development, the catalytic hydrogenation of renewable fatty acid methyl esters (FAMs) to produce high-value-added fatty alcohols has attracted significant attention. As an important raw material in fields such as surfactants, cosmetics, and pharmaceuticals, the development of green synthetic pathways for fatty alcohols offers both environmental and economic benefits. Methyl laurate, methyl myristate, and methyl palmitate are common FAMEs, and differences in their carbon chain length and structure lead to distinct reaction characteristics and product selectivity. Studying the performance of copper-based catalysts in the hydrogenation of various FAMEs is crucial for achieving green conversion of FAMEs to fatty alcohols. Summary of the Invention

[0003] (1) Technical problems solved

[0004] In response to the deficiencies in the prior art, the present invention provides a preparation method of a Cu / ZnO / Al2O3 / ZrO2 catalyst and its application in the hydrogenation reaction of fatty acid methyl esters. By optimizing the component ratio and calcination temperature, the catalyst is applied in fatty acid methyl ester hydrogenation experiments to maintain good catalytic activity and selectivity, reduce the cost of the hydrogenation catalyst, and solve the problems of low activity and poor selectivity of traditional catalysts.

[0005] (2) Technical solution

[0006] The present invention provides the following technical solution: In order to achieve the above-mentioned purpose, the preparation of a Cu / ZnO / Al2O3 / ZrO2 catalyst and its application in the hydrogenation reaction of fatty acid methyl esters are specifically as follows:

[0007] Catalyst preparation: 1.0M Cu(NO3)2, 1.0M Zn(NO3)2, 1.0M Al(NO3)3, 1.0M Zr(NO3)4, and 0.5M Na2CO3 as a precipitant were prepared. The metal solutions were weighed in a certain proportion and poured into a flask, heated to 75°C. At this temperature, 0.5M Na2CO3 was added dropwise. Simultaneously, the precipitant was slowly and uniformly added dropwise to the metal solution using a 250mL dropping funnel until the pH reached approximately 7.5. Stirring was continued at 75°C for 2 hours, followed by aging for 1 hour. The precipitate was filtered and washed until neutral. The filter cake was vacuum dried at 100°C for 12 hours and calcined at 450°C in a muffle furnace at a heating rate of 5°C / min for 4 hours. Finally, the mixture was ground and sieved to 80-100 mesh.

[0008] The catalyst was used to hydrogenate fatty acid methyl esters. The reaction was carried out in a 1L batch autoclave. 6g of fresh catalyst, 20g of raw materials and 400ml of solvent were added and the autoclave was sealed.

[0009] At a certain reaction temperature and pressure, after a period of reaction, the catalyst and the reaction liquid are separated by filtration, and the filtered reaction liquid is subjected to quantitative and qualitative analysis by gas chromatography.

[0010] Preferably, the copper precursor is copper nitrate trihydrate;

[0011] Preferably, the zinc precursor is zinc nitrate hexahydrate;

[0012] Preferably, the aluminum precursor is aluminum nitrate nonahydrate;

[0013] Preferably, the zirconium precursor is zirconium nitrate pentahydrate;

[0014] Preferably, the fatty acid methyl ester is methyl laurate, methyl myristate and methyl palmitate;

[0015] Preferably, the mass ratio of the catalyst to the raw material is 0.3;

[0016] Preferably, the reaction solvent is p-menane;

[0017] In the present invention, the prepared quaternary catalyst is used in the hydrogenation of fatty acid methyl esters in a batch autoclave with a catalyst-to-raw material mass ratio of 0.3 and p-menthane as the preferred solvent. Under reaction conditions of 200°C, 8 MPa, and 8 hours, the conversion rates of the raw materials, methyl laurate, methyl myristate, and methyl palmitate, all reached over 90%, reaching industrial application levels.

[0018] Compared with existing technologies, the present invention has the advantages of synthesizing a Cu-Zn-Al-Zr quaternary catalyst by coprecipitating multiple metal precursors in an alkaline environment. This catalyst was then applied to three different fatty acid methyl ester hydrogenation processes. This catalyst demonstrated universal applicability for fatty acid methyl ester hydrogenation. Furthermore, the catalyst's preparation cost is relatively low, suggesting promising prospects for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the XRD spectrum of the Cu / ZnO / Al2O3 / ZrO2 catalyst prepared by the present invention after reaction;

[0020] Figure 2 This is a SEM image of the Cu / ZnO / Al2O3 / ZrO2 catalyst prepared in the present invention;

[0021] Figure 3This is a gas chromatogram of the catalyst prepared in the present invention after hydrogenation of methyl laurate;

[0022] Figure 4 This is a gas chromatogram of the catalyst prepared in the present invention after hydrogenation of methyl myristate;

[0023] Figure 5 This is a gas chromatogram of the catalyst prepared in the present invention after hydrogenation of methyl palmitate;

[0024] Figure 6 This is the thermogravimetric curve of the Cu / ZnO / Al2O3 / ZrO2 catalyst prepared by the co-precipitation method of the present invention before and after the reaction. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] Example 1:

[0027] Weigh 6g of fresh catalyst and 6g of methyl laurate, add 400ml of methanol as the solvent, and seal the autoclave. Before the reaction, pass hydrogen into the autoclave for airtightness testing. Once the airtightness meets the requirements, replace the autoclave with hydrogen. Set the hydrogen pressure to 8MPa and react at 200°C for 8h. Then, separate the catalyst and reaction liquid by filtration. Finally, perform quantitative and qualitative analysis of the reaction liquid using a GC-9790 gas chromatograph.

[0028] Example 2:

[0029] Weigh 6g of fresh catalyst and 6g of methyl laurate, add 400ml of toluene as the solvent, and seal the autoclave. Before the reaction, purge the autoclave with hydrogen to test its tightness. Once the airtightness meets the requirements, replace the autoclave with hydrogen. Set the hydrogen pressure to 8MPa and react at 200°C for 8h. Then, separate the catalyst and reaction liquid by filtration. Finally, perform quantitative and qualitative analysis of the reaction liquid using a GC-9790 gas chromatograph.

[0030] Example 3:

[0031] Weigh 6g of fresh catalyst and 12g of methyl laurate, add 400ml of methanol as the solvent, and seal the autoclave. Before the reaction, pass hydrogen into the autoclave for airtightness testing. Once the airtightness meets the requirements, replace the autoclave with hydrogen. Set the hydrogen pressure to 8MPa, and after reacting at 200°C for 8h, separate the catalyst and reaction liquid by filtration. Finally, perform quantitative and qualitative analysis of the reaction liquid using a GC-9790 gas chromatograph.

[0032] Example 4:

[0033] Weigh 6g of fresh catalyst and 20g of methyl laurate in 400ml of solvent, then seal the autoclave. Before the reaction, purge the autoclave with hydrogen to ensure it meets airtightness standards. Once the autoclave is airtight, replace the atmosphere with hydrogen. Set the hydrogen pressure to 8MPa and react at 200°C for 8h. Separate the catalyst and reaction liquid by filtration. Finally, perform quantitative and qualitative analysis of the reaction liquid using a GC-9790 gas chromatograph.

[0034] Example 5:

[0035] Weigh 6g of fresh catalyst and 20g of methyl myristate and dissolve them in 400ml of solvent. Seal the autoclave. Before the reaction, purge the autoclave with hydrogen to ensure it meets airtightness standards. Once the autoclave is airtight, replace the atmosphere with hydrogen. Set the hydrogen pressure to 8MPa and react at 200°C for 8h. Separate the catalyst and reaction solution by filtration. Finally, perform quantitative and qualitative analysis of the reaction solution using a GC-9790 gas chromatograph.

[0036] Example 6:

[0037] Weigh 6g of fresh catalyst and 20g of methyl palmitate and dissolve them in 400ml of solvent. Seal the autoclave. Before the reaction, purge the autoclave with hydrogen to ensure it meets the airtightness requirements. Once the autoclave is airtight, replace the atmosphere with hydrogen. Set the hydrogen pressure to 8MPa and react at 200°C for 8h. Separate the catalyst and reaction liquid by filtration. Finally, perform quantitative and qualitative analysis of the reaction liquid using a GC-9790 gas chromatograph.

[0038] Table 1 Effect of catalyst on catalytic hydrogenation of fatty acid methyl esters under different conditions

[0039]

[0040]

[0041] As shown in Table 1, when the prepared catalyst was used for the selective hydrogenation of fatty acid methyl esters using para-menthane as the solvent, under the reaction conditions of 200°C, 8 MPa, and 8 h, the conversion rates of the three fatty acid methyl esters were all above 90%, and the products obtained were mainly the corresponding fatty alcohols and alkanes, indicating that the catalyst has good reactivity. The catalyst prepared by the present invention can meet the needs of industrial production.

[0042] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. Preparation of a Cu / ZnO / Al2O3 / ZrO2 catalyst and its application in fatty acid methyl ester hydrogenation reaction, characterized by: The catalyst uses copper as the active center and is modified by adding multiple non-precious metals. The prepared catalyst is applied to three different fatty acid methyl esters. Experiments are conducted using different polar solvents, methanol, ethanol, and ethyl acetate, as well as non-polar solvents, cyclohexane, n-hexane, and p-menthane. The ratio of catalyst to raw materials is adjusted. The fatty acid methyl esters are dissolved in the solvents, and H2 is introduced at a certain temperature and pressure to perform a catalytic hydrogenation reaction to obtain corresponding alcohols and alkanes. The preparation method of the catalyst and the catalytic hydrogenation reaction conditions are specifically as follows: 1) Preparation of catalyst: 1.0M Cu(NO3)2, 1.0M Zn(NO3)2, 1.0M Al(NO3)3, 1.0M Zr(NO3)4 and 0.5M Na2CO3 as a precipitant were prepared respectively, the metal solutions were measured and poured into a flask in a certain proportion and heated to 75°C, 0.5M Na2CO3 was added dropwise at this temperature, and the precipitant was slowly and uniformly added dropwise to the metal solution using a dropping funnel, with the drop rate controlled at about one drop every two seconds, until the pH reached about 7.5, and the mixture was stirred continuously at 75°C for 2h, aged for 1h, and the precipitate was filtered and washed until neutral, the filter cake was vacuum dried at 100°C for 12h, and calcined at 450°C for 4h in a muffle furnace at a heating rate of 5°C / min; finally, the mixture was ground and sieved; 2) Catalyzed Hydrogenation of Fatty Acid Methyl Ester: The reaction was carried out in a 1 L batch autoclave. 6 g of fresh catalyst, 20 g of fatty acid methyl ester, and 400 ml of solvent were added, and the autoclave was sealed. Before the reaction, 3 MPa of H₂ was introduced into the autoclave to check for airtightness. If the airtightness was good, the autoclave was replaced with hydrogen three times to remove air. After a period of reaction at a certain reaction temperature and pressure, the catalyst and reaction solution were separated by filtration, and the filtered reaction solution was subjected to quantitative and qualitative analysis by gas chromatography.

2. The preparation of a Cu / ZnO / Al2O3 / ZrO2 catalyst according to claim 1 and its application in the hydrogenation reaction of fatty acid methyl esters, characterized in that: The concentration of the precipitant sodium carbonate solution is 0.5 mol / L.

3. The preparation of a Cu / ZnO / Al2O3 / ZrO2 catalyst according to claim 1 and its application in the hydrogenation reaction of fatty acid methyl esters, characterized in that: The pH after precipitation is controlled at 7.5-8.

4. The preparation of a Cu / ZnO / Al2O3 / ZrO2 catalyst according to claim 1 and its application in the hydrogenation reaction of fatty acid methyl esters, characterized in that: The molar ratio of Cu2+:Zn2+:Al3+:Zr4+ is 2:1:0.1:0.

9.

5. The preparation of a Cu / ZnO / Al2O3 / ZrO2 catalyst according to claim 1 and its application in the hydrogenation reaction of fatty acid methyl esters, characterized in that: The calcination temperature was controlled at 450°C.

6. The preparation of a Cu / ZnO / Al2O3 / ZrO2 catalyst according to claim 1 and its application in the hydrogenation reaction of fatty acid methyl esters, characterized in that: The reaction temperature of the catalytic hydrogenation reaction is 200° C. and the pressure is 8 MPa.

7. The preparation of a Cu / ZnO / Al2O3 / ZrO2 catalyst according to claim 1 and its application in the hydrogenation of fatty acid methyl esters, characterized in that: The fatty acid methyl esters selected for the catalytic hydrogenation are methyl laurate, methyl myristate and methyl palmitate.

8. The preparation of a Cu / ZnO / Al2O3 / ZrO2 catalyst according to claim 1 and its application in the hydrogenation of fatty acid methyl esters, characterized in that: The solvent used in the catalytic hydrogenation reaction is a non-polar solvent.

9. The preparation of a Cu / ZnO / Al2O3 / ZrO2 catalyst according to claim 1 and its application in the hydrogenation of fatty acid methyl esters, characterized in that: The mass ratio of the catalyst to the raw material in the hydrogenation of fatty acid methyl ester catalyzed by the catalyst is 0.3.

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