A catalyst for selective hydrogenation of furfuryl alcohol and a preparation method and application thereof

Abstract

This invention discloses a furfuryl alcohol selective hydrogenation catalyst, its preparation method, and its application. The catalyst preparation method includes the following steps: 1) mixing a copper source, a cobalt source, a support, and water uniformly, adding an alkaline solution to adjust the pH to 7-11 and reacting, then filtering, washing, and drying to obtain a precursor; 2) calcining the precursor at high temperature and reducing it with hydrogen to obtain the furfuryl alcohol selective hydrogenation catalyst. This invention utilizes a simple and environmentally friendly co-precipitation and impregnation method at room temperature to achieve large-scale batch production of non-precious metal catalysts. The obtained material exhibits excellent catalytic performance in furfuryl alcohol hydrogenation rearrangement: furfuryl alcohol conversion >99%, alcohol-ketone yield >85%, and carbon balance reaching 90%.

Description

Technical Field

[0001] This invention relates to a selective hydrogenation catalyst for furfuryl alcohol, its preparation method, and its application. By adjusting the pH value during the precursor preparation process to control the acid content, highly selective hydrogenation of furfuryl alcohol can be achieved. This invention belongs to the fields of catalyst preparation technology, heterogeneous catalytic reaction technology, and fine chemical synthesis technology. Background Technology

[0002] Cyclopentanol and cyclopentanone, as important fine chemical intermediates, serve as raw materials for the fragrance and pharmaceutical industries, used to prepare novel fragrances such as methyl dihydrojasmonate and various anti-inflammatory and anticancer drugs. They are also widely used in biochemical research, the synthesis of pesticides and herbicides, and other applications. Currently, the main process for preparing cyclopentanol domestically and internationally is the cyclopentene hydration method, but this method has a low conversion rate and a large recycling rate of the cyclopentene feedstock. Cyclopentanone, on the other hand, is derived from the adipic acid pyrolysis process, which involves complex post-processing of the product and generates a large amount of pollutants during the reaction. 1,4-Pentanediol is a highly valuable bio-diol that can be used to synthesize high-performance biodegradable polyesters, thermoplastics, and polyurethanes, as well as high-value-added chemicals such as isoprene, 2,3-pentanedione, and 2-methyltetrahydrofuran. 1,4-Pentanediol can be generated in one step from levulinic acid under the catalysis of noble metal catalysts, but the catalysts often have low activity and the reaction conditions are harsh, limiting its industrial applications.

[0003] Furfuryl alcohol is an important chemical raw material widely used in pharmaceuticals, pesticides, dyes, and plastics industries. However, due to the presence of carbonyl groups in its molecular structure, furfuryl alcohol is prone to oxidation during use, thus affecting its performance. To address this issue, researchers have begun exploring hydrogenation rearrangement methods to modify the structure of furfuryl alcohol and improve its stability. The furfuryl alcohol hydrogenation rearrangement technology system mainly involves two key areas: catalyst preparation technology and reaction process optimization. Regarding catalyst preparation technology, since 2019, researchers have focused on developing metal composite oxide catalysts, optimizing mesoporous molecular sieve catalysts, and designing metal-acid oxide bifunctional catalysts, aiming to improve catalyst activity, selectivity, and stability. Simultaneously, in the area of ​​reaction process optimization, research focuses on reactor structure optimization, reaction condition optimization, and the integration of continuous reaction processes, with the aim of achieving higher product yields, better process control, and lower operating costs.

[0004] Transition metal / oxide supported catalysts, characterized by their low cost, high activity, and good durability, have attracted considerable attention from researchers. Metal doping can generate more active sites; different supports can effectively alter the electrochemical activity of materials, making them well-suited for applications in catalytic hydrogenation. Studies have shown that Lewis acids are key factors promoting furan ring rearrangement, while... Acid sites promote polymerization and produce undesirable products. Strong acid environments easily lead to the polymerization of raw materials and products. Excessive strong acid sites on the support surface will accelerate the polymerization reaction, resulting in low product yield.

[0005] Therefore, it is of great significance to develop a furfuryl alcohol rearrangement hydrogenation catalyst supported by an acidic metal oxide in this field. Summary of the Invention

[0006] In view of this, one of the objectives of the present invention is to provide a selective hydrogenation catalyst for furfuryl alcohol and a preparation method thereof. The catalyst is a Cu / Co bimetallic supported catalyst, and the active sites of the precursor are adjusted by controlling the pH value during the preparation process to obtain a highly active catalyst with uniform metal dispersion.

[0007] The second objective of this invention is to provide the application of the above-mentioned catalyst in the selective hydrogenation of furfuryl alcohol, which can achieve the effective conversion of furfuryl alcohol to cyclopentanol and cyclopentanone products, and improve the efficiency and selectivity of heterogeneous catalytic reactions.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing a furfuryl alcohol selective hydrogenation catalyst, comprising the following steps:

[0010] 1) Mix copper source, cobalt source, carrier and water evenly, add alkaline solution to adjust the pH value to 7-11 and carry out the reaction, then filter, wash and dry to obtain the precursor;

[0011] 2) The precursor is calcined at high temperature and reduced with hydrogen to obtain the furfuryl alcohol selective hydrogenation catalyst.

[0012] In one embodiment, the copper source in step 1) is a copper-soluble compound such as a copper salt, preferably one or more of copper nitrate, copper chloride, copper sulfate, and copper acetate.

[0013] In one embodiment, the cobalt source in step 1) is a cobalt-soluble compound such as a cobalt salt, preferably one or more of cobalt chloride, cobalt nitrate, cobalt sulfate, and cobalt acetate.

[0014] In one embodiment, the support in step 1) is an acidic metal oxide, preferably one or more of zirconium oxide, titanium oxide, and aluminum oxide;

[0015] Preferably, the carrier has a large number of L-acid active sites and a specific surface area ≥150m². 2 / g, for example, 150m 2 / g、180m 2 / g、200m 2 / g、250m 2 / g、300m2 / g, 350m 2 / g and above, etc.

[0016] In one implementation, the molar ratio of cobalt source to copper source in step 1) is 1:2 to 10, for example, 1:2, 1:4, 1:6, 1:8, 1:10, etc.

[0017] In one implementation, step 1) is a molar ratio of 1:4 to 6 with the carrier, based on the total molar amount of the cobalt source and the copper source, for example, 1:4, 1:5, 1:6, etc.

[0018] In one embodiment, step 1) has a concentration in water of 20–100 g / L based on the total mass of the cobalt and copper sources, such as 20 g / L, 40 g / L, 60 g / L, 80 g / L, 100 g / L, etc.

[0019] In one implementation, step 1) involves adding alkali solution to adjust the pH value, with the pH adjustment range being 7 to 11, such as 7, 8, 9, 10, 11, etc.

[0020] The alkaline solution contains an alkaline compound, a strong base-weak acid salt, preferably one or more of sodium hydroxide, sodium carbonate, and ammonia water.

[0021] Preferably, the alkaline solution is an aqueous solution with a concentration of 2 to 10 wt%.

[0022] In one embodiment, the reaction described in step 1) does not have a special temperature requirement and can be carried out at room temperature. The reaction time is 18 to 24 hours, for example, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours, 24 hours, etc.

[0023] Preferably, before the reaction, the raw materials copper source, cobalt source, carrier and water are thoroughly mixed by stirring for 30 to 60 minutes, such as 30 minutes, 40 minutes, 50 minutes, 60 minutes, etc.

[0024] After the reaction in step 1) of the preparation method of the present invention is completed, post-processing processes such as filtration, washing, and drying are also included, which are routine operations in the field. For example, filtration can be carried out by plate and frame filtration, and the pore size of the microporous filter membrane used is 200-500 nm; for example, the washing solvent is water, and the washing is carried out 3-5 times; for example, it is dried in a vacuum drying oven at 80-100℃ for 8-24 hours.

[0025] In one embodiment, the high-temperature calcination in step 2) lasts for 3 to 5 hours, for example, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, etc., and the temperature is 450 to 550 degrees Celsius, for example, 450 degrees Celsius, 480 degrees Celsius, 500 degrees Celsius, 520 degrees Celsius, 550 degrees Celsius, etc.

[0026] Preferably, the heating rate during the calcination process is 5–15 °C / min, and the cooling method after calcination is natural cooling;

[0027] Before high-temperature calcination, the precursor is ground to a particle size of 30-100 mesh.

[0028] In one embodiment, the hydrogen reduction in step 2) is carried out at a temperature of 170–200°C, such as 170°C, 180°C, 190°C, 200°C, etc., at a pressure of 3–6 MPa, such as 3 MPa, 4 MPa, 5 MPa, 6 MPa, etc., and for a time of 10–12 hours, such as 10 hours, 10.5 hours, 11 hours, 11.5 hours, 12 hours, etc.

[0029] Secondly, the present invention provides a furfuryl alcohol selective hydrogenation catalyst prepared by the above method;

[0030] The catalyst is a Cu / Co bimetallic supported catalyst.

[0031] Thirdly, the present invention provides the application of the above-mentioned furfuryl alcohol selective hydrogenation catalyst.

[0032] Specifically, a method for selectively hydrogenating furfuryl alcohol to produce cyclopentanol and cyclopentanone involves using furfuryl alcohol as a starting material and carrying out a selective hydrogenation reaction in a solvent under the action of the aforementioned selective hydrogenation catalyst.

[0033] The relevant operations and process conditions in the preparation method of this invention, as well as the apparatus used, can all be carried out using corresponding conventional selections in the art, and there are no particular restrictions. Those skilled in the art can optimize the process based on existing technology and known processes according to actual needs. For example, the conditions listed in the following embodiments of this invention can be used:

[0034] The solvent contains water; furthermore, it may also contain other optional solvents such as tetrahydrofuran, methanol, etc.

[0035] In the solution formed by furfuryl alcohol and solvent, the concentration of furfuryl alcohol is 5-20%.

[0036] The selective hydrogenation catalyst for furfuryl alcohol is 5–20 g / L of the mass of the solution formed by furfuryl alcohol and solvent.

[0037] The selective hydrogenation reaction is carried out at a temperature of 150–180°C, a reaction pressure of 2–5 MPa, and a reaction time of 10–15 h.

[0038] The advantages of this invention over the prior art are:

[0039] This invention, under relatively mild conditions, utilizes a simple and reproducible impregnation and co-precipitation method, using acidic metal oxides as supports to load Cu and Co bimetals, and controlling the pH at the reaction endpoint to obtain a catalyst with uniform metal dispersion and controllable acid content. The surface of acidic metal oxides possesses numerous moderately strong L-acid centers, providing a mild acidic environment for the formation of oxocations and resulting in good product yields. Using acidic metal oxides such as zirconium oxide and titanium oxide as supports, and doping them with metal atoms, the pH can be controlled during preparation to obtain different total acid contents, allowing for the design and preparation of highly active furfuryl alcohol rearrangement hydrogenation catalysts. The preparation method provided by this invention does not require precise temperature control, nor the use of additional solvents or template agents, avoiding cumbersome subsequent extraction, separation, acid-base etching, and other steps. The method provided by this invention is low-cost, high-yield, and reduces the amount of chemical reagents used. By optimizing the pH value, it can effectively prevent the polymerization of furfuryl alcohol and achieve product ratio control, thereby improving carbon balance, which is of great significance for industrial production.

[0040] The Cu / Co bimetallic catalyst prepared by this invention has a regular morphology and uniform particle size, and the proportion of different furfuryl alcohol hydrogenation products can be controlled under different reaction conditions. For example, under the conditions of controlling the pH value to 9, calcination temperature to 500℃, reaction temperature to 180℃, and reaction pressure to 2MPa, a furfuryl alcohol conversion rate of >99%, an alcohol-ketone yield of >85%, and a carbon balance of 90% can be achieved.

[0041] This invention provides a new reaction pathway that allows for the efficient conversion of furfuryl alcohol into different products by adjusting the pH value. This is of great significance for improving the efficiency and selectivity of heterogeneous catalytic reactions. Detailed Implementation

[0042] The present invention will be further described below with reference to embodiments and comparative examples, but the present invention is not limited to the following embodiments, and should also include any other known modifications within the scope of the claims of the present invention.

[0043] Unless otherwise specified, the reagents, materials and instruments used in the following examples are all conventional reagents, materials and instruments in the art, and can be obtained commercially. The reagents involved can also be synthesized by conventional methods in the art.

[0044] Example 1

[0045] Preparation of selective hydrogenation catalysts for furfuryl alcohol:

[0046] Step 1: Weigh out cobalt chloride and copper chloride in a molar ratio of 1:2, and weigh out alumina (with a specific surface area of ​​200 m²) in a molar ratio of metal salt (cobalt chloride and copper chloride) to zirconium dioxide of 1:5. 2Metal salt and alumina were added to water and stirred thoroughly for 60 minutes to achieve a metal salt concentration of 20 g / L. A 5 wt% sodium hydroxide aqueous solution was added dropwise to adjust the pH to 7, and the reaction was continued with stirring for 18 hours. After the reaction was complete, the mixture was filtered through a plate and frame filter (microporous membrane with a pore size of 200 nm) and washed three times with water to obtain a precipitate. The resulting filter cake was placed in a vacuum drying oven at 80℃ for 12 hours, dried, and ground to obtain the precursor. The product was named CuCo / Al2O3.

[0047] Step 2: The 100-mesh precursor after grinding was placed in a muffle furnace for calcination. The temperature was raised to 550℃ at a rate of 5℃ / min and held for 3 hours. After natural cooling, it was placed in a reactor and charged with hydrogen. The reduction temperature was 180℃, the pressure was 4MPa, and the time was 10 hours to obtain the furfuryl alcohol selective hydrogenation catalyst CuCo / Al2O3-CAT.

[0048] Step 3: Place 20g of the catalyst obtained above into a 2L reactor, add 1L of a 20wt% furfuryl alcohol-water / tetrahydrofuran solution, introduce hydrogen gas and heat the reaction to 150℃, 5MPa, and 10h. Take out the reaction solution for composition analysis, and the results are shown in Table 1.

[0049] Example 2

[0050] Preparation of selective hydrogenation catalysts for furfuryl alcohol:

[0051] Step 1: Weigh cobalt nitrate and copper nitrate in a molar ratio of 1:6, and weigh zirconium oxide (with a specific surface area of ​​150 m²) in a molar ratio of metal salt (cobalt nitrate and copper nitrate) to zirconium dioxide of 1:4. 2 Metal salt and zirconium oxide were added to water and stirred thoroughly for 40 minutes to achieve a metal salt concentration of 25 g / L. A 10 wt% sodium carbonate aqueous solution was added dropwise to adjust the pH to 11, and the reaction was continued with stirring for 24 hours. After the reaction was complete, the mixture was filtered through a plate and frame filter (microporous membrane with a pore size of 500 nm) and washed three times with water to obtain a precipitate. The resulting filter cake was placed in a vacuum drying oven at 100℃ for 10 hours, dried, and ground to obtain the precursor. The product was named CuCo / ZrO2.

[0052] Step 2: The 50-mesh precursor after grinding was placed in a muffle furnace for calcination. The temperature was raised to 450℃ at a rate of 10℃ / min and held for 5 hours. After natural cooling, it was placed in a reactor and charged with hydrogen. The reduction temperature was 170℃, the pressure was 6MPa, and the time was 10 hours to obtain the furfuryl alcohol selective hydrogenation catalyst CuCo / ZrO2-CAT.

[0053] Step 3: Place 10g of the catalyst obtained above into a 2L reactor, add 1L of a 5wt% furfuryl alcohol aqueous solution, introduce hydrogen gas and heat the reaction to 160℃, 3MPa, and 12h. Take out the reaction solution for composition analysis, and the results are shown in Table 1.

[0054] Example 3

[0055] Preparation of selective hydrogenation catalysts for furfuryl alcohol:

[0056] Step 1: Weigh cobalt acetate and copper acetate in a molar ratio of 1:2, and weigh titanium dioxide (with a specific surface area of ​​180 m²) in a molar ratio of metal salt (cobalt acetate and copper acetate) to zirconium dioxide of 1:6. 2 Metal salt and titanium oxide were added to water and stirred thoroughly for 30 minutes to achieve a metal salt concentration of 40 g / L. A 2 wt% ammonia solution was added dropwise to adjust the pH to 9, and the reaction was continued with stirring for 20 hours. After the reaction was complete, the mixture was filtered through a plate and frame filter (microporous membrane with a pore size of 300 nm) and washed five times with water to obtain a precipitate. The resulting filter cake was placed in a vacuum drying oven at 100℃ for 8 hours, dried, and ground to obtain the precursor. The product was named CuCo / TiO2.

[0057] Step 2: The 30-mesh precursor after grinding was placed in a muffle furnace for calcination. The temperature was raised to 500℃ at a rate of 15℃ / min and held for 4 hours. After natural cooling, it was placed in a reactor and charged with hydrogen. The reduction temperature was 200℃, the pressure was 3MPa, and the time was 12 hours to obtain the furfuryl alcohol selective hydrogenation catalyst CuCo / TiO2-CAT.

[0058] Step 3: Place 5g of the aforementioned catalyst into a 2L reactor, add 1L of a 15wt% furfuryl alcohol water / methanol solution, introduce hydrogen gas and heat the reaction to 180℃, 2MPa, and 10h. Take out the reaction solution for composition analysis, and the results are shown in Table 1.

[0059] Comparative Example 1

[0060] A selective hydrogenation catalyst for furfuryl alcohol was prepared according to the method in Example 1, except that the pH value was adjusted to 5 during the catalyst preparation process, while other operations and conditions remained unchanged, and the catalyst CuCo / Al2O3-CAT was obtained.

[0061] The catalyst was used for selective hydrogenation of furfuryl alcohol according to step 3 of Example 1, and the analytical results are shown in Table 1.

[0062] Comparative Example 2

[0063] The catalyst was prepared according to the method in Example 2, except that the pH value was adjusted to 13 during the catalyst preparation process, while other operations and conditions remained unchanged, and the CuCo / ZrO2-CAT catalyst was obtained.

[0064] The catalyst was used for selective hydrogenation of furfuryl alcohol according to step 3 of Example 1, and the analytical results are shown in Table 1.

[0065] Table 1. Results of analysis of examples and comparative examples.

[0066]

Claims

1. A method for preparing a furfuryl alcohol selective hydrogenation catalyst, characterized in that the step... include: 1) Mix copper source, cobalt source, carrier and water evenly, add alkaline solution to adjust the pH value to 7-11 and carry out the reaction, then filter, wash and dry to obtain the precursor; 2) The precursor is calcined at high temperature and reduced with hydrogen to obtain the furfuryl alcohol selective hydrogenation catalyst.

2. The preparation method according to claim 1, characterized in that, Step 1) The copper source is a copper-soluble compound, preferably one or more of copper nitrate, copper chloride, copper sulfate, and copper acetate; and / or Step 1) The cobalt source is a cobalt-soluble compound, preferably one or more of cobalt chloride, cobalt nitrate, cobalt sulfate, and cobalt acetate; and / or Step 1) The support is an acidic metal oxide, preferably one or more of zirconium oxide, titanium oxide, and aluminum oxide; preferably, the specific surface area of ​​the support is ≥150 m². 2 / g.

3. The preparation method according to claim 1, characterized in that, Step 1) The molar ratio of cobalt source to copper source is 1:2 to 10; and / or Step 1) The molar ratio of the cobalt source and the copper source to the carrier is 1:4 to 6, based on the total molar amount of the cobalt source and the copper source; and / or Step 1) The concentration in water is 20-100 g / L based on the total mass of the cobalt and copper sources.

4. The preparation method according to claim 1, characterized in that, The alkaline solution in step 1) contains an alkaline compound, a strong base-weak acid salt, preferably one or more of sodium hydroxide, sodium carbonate, and ammonia water; Preferably, the alkaline solution is an aqueous solution with a concentration of 2 to 10 wt%.

5. The preparation method according to claim 1, characterized in that, The reaction time in step 1) is 18–24 hours.

6. The preparation method according to claim 1, characterized in that, The high-temperature calcination described in step 2) lasts for 3 to 5 hours at a temperature of 450 to 550°C. Preferably, the heating rate during the calcination process is 5–15 °C / min; Preferably, the precursor is ground before high-temperature calcination to a particle size of 30-100 mesh.

7. The preparation method according to claim 1, characterized in that, Step 2) involves hydrogen reduction at a temperature of 170–200°C, a pressure of 3–6 MPa, and a time of 10–12 hours.

8. A furfuryl alcohol selective hydrogenation catalyst prepared by the method according to any one of claims 1-7.

9. A method for selective hydrogenation of furfuryl alcohol to produce cyclopentanol and cyclopentanone, characterized in that, It is prepared by selective hydrogenation reaction of furfuryl alcohol as starting material in a solvent under the action of the furfuryl alcohol selective hydrogenation catalyst prepared by any one of claims 1-7, or the furfuryl alcohol selective hydrogenation catalyst of claim 8.

10. The method according to claim 9, characterized in that, The solvent contains water; optionally, it may also contain other optional solvents, such as tetrahydrofuran, methanol; and / or In the solution formed by furfuryl alcohol and solvent, the concentration of furfuryl alcohol is 5-20%; and / or The furfuryl alcohol selective hydrogenation catalyst is 5–20 g / L of the solution mass formed by furfuryl alcohol and solvent; and / or The selective hydrogenation reaction is carried out at a temperature of 150–180°C, a reaction pressure of 2–5 MPa, and a reaction time of 10–15 h.

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