Ancoupled hydrogenation catalyst, its preparation method and application

Abstract

The present invention relates to the technical field of catalysts, and provides a coupling hydrogenation catalyst, a preparation method thereof and an application. In the present invention, the active component Ni is first loaded on the HZSM-5 molecular sieve through precipitation and reduction, and then the noble metal Pd with stronger hydrogen dissociation ability is loaded onto the base metal Ni providing hydrogenation sites by replacement. This catalyst structure allows hydrogen to first dissociate into hydrogen atoms on the noble metal, and the hydrogen atoms reach the surface of the base metal providing hydrogenation sites through the way of overflow and react with acetone molecules bound to the base metal to carry out hydrogenation reaction. The preparation method of the present invention can avoid the coverage of the less content noble metal by the base metal, thereby reducing the loading amount of the noble metal and lowering the catalyst cost. The coupling hydrogenation catalyst prepared by the present invention can simultaneously achieve high conversion rate and high selectivity, the yield of the target product is relatively high, and the reaction conditions are mild and the process conditions are widely adaptable.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and particularly to a coupling hydrogenation catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Methyl isobutyl ketone (also known as 4-methyl-2-pentanone, abbreviated as MIBK in English) is a medium-boiling solvent and organic synthesis raw material with excellent performance. Due to its good physical and chemical properties, it is widely used in fields such as coatings, organic synthesis, and medicine. The MIBK consumption market in China is mainly rubber antioxidant 4020. In addition, it can also be used as a high-grade coating solvent, lubricating oil dewaxing agent, adhesive, organic synthesis extractant, diluent, and surfactant in aerospace, home decoration, etc. Rubber antioxidant 4020 synthesized from MIBK is currently an internationally common high-efficiency and low-toxic rubber antioxidant, and it is an irreplaceable variety for antioxidants used in radial tires.

[0003] At present, at home and abroad, methyl isobutyl ketone is mainly prepared from acetone. The preparation methods are mainly divided into the acetone three-step method and the acetone one-step method. Since the reaction mechanism and the required catalyst are different for each step in the acetone three-step method, each step needs to be carried out in a different reactor, which results in disadvantages such as a long production process flow, low production efficiency, and high product cost. The acetone one-step method uses a coupling hydrogenation catalyst that simultaneously has an acid active center and a metal hydrogenation active center, enabling acetone to simultaneously complete condensation, dehydration, and hydrogenation reactions in one reactor. The acetone one-step method has low equipment investment, a simple process flow, and a high product yield, and has become the mainstream method for preparing methyl isobutyl ketone in the industry. The key to the acetone one-step method is to develop a coupling hydrogenation catalyst that simultaneously has the functions of condensation dehydration and hydrogenation.

[0004] The coupling hydrogenation catalyst consists of metal nanoparticles and a support. The support provides acidic active centers for the dehydration condensation of acetone to form the intermediate product mesityl oxide. Commonly used supports at present include ion exchange resins, metal oxides, molecular sieves, etc. Ion exchange resins have excellent selectivity for the target product MIBK, but poor thermal stability, short service life, and the loaded metal nanoparticles are prone to loss. Metal oxides have good thermal stability, but the selectivity of such catalysts for MIBK is relatively low, and the reaction usually needs to be carried out under high pressure, with large energy consumption and poor economy. Molecular sieve supports provide excellent shape selectivity due to their unique pore structures, which can effectively improve the selectivity of the target product. Among them, the catalyst with HZSM-5 molecular sieve as the support has the best catalytic performance. The metal is loaded on the support to provide hydrogenation active centers, promoting the hydrogenation of the intermediate product to form MIBK. The research on metal hydrogenation active components is mainly divided into two categories. One category is noble metals, mainly Pd, followed by Pt, Rh. Such catalysts have relatively high selectivity for MIBK, but are expensive and have high catalyst costs. The other category is non-noble metals, mainly including Ni, Cu, Mg, etc. Such catalysts are inexpensive, but have relatively low selectivity for MIBK.

[0005] Yang Piaoping et al. prepared Pd / ZSM-5 catalysts by ion exchange method in the article "Effect of acidic and metallic sites on the catalytic performance of Pd / ZSM-5 catalysts in the one-step synthesis of MIBK". The loading amount of Pd was 0.55%. A fixed-bed reactor was used as the catalyst evaluation device. The results showed that under the reaction conditions of reaction temperature 160 °C and reaction pressure 4 MPa, the conversion rate of acetone was 43.6%, and the selectivity of MIBK was 93.8%. Li Hongxia et al. prepared Pd-Cu-Zn-Ni / HZSM-5 catalysts by ion exchange method in the article "Preparation and evaluation of multi-metal catalysts for the synthesis of MIBK". A reaction kettle was used as the catalyst evaluation device. The results showed that under the reaction conditions of reaction temperature 160 °C and reaction pressure 18 Kg / cm 2 under the reaction conditions of reaction temperature 160 °C and reaction pressure 18 Kg / cm, the conversion rate of acetone was 42.7%, and the selectivity of MIBK was 95.6%.

[0006] To sum up, at present, when using the hydrogenation coupling catalyst in the one-step preparation of MIBK from acetone, there are generally problems such as low conversion rate, high noble metal content, and poor economy. Summary of the Invention

[0007] In view of this, the present invention provides a coupling hydrogenation catalyst, a preparation method thereof and an application thereof. The hydrogenation coupling catalyst prepared by the present invention can simultaneously achieve high conversion rate and high selectivity, and has a small loading amount of precious metal Pd and low catalyst cost.

[0008] In order to achieve the above invention object, the present invention provides the following technical solutions:

[0009] A preparation method of a coupling hydrogenation catalyst, comprising the following steps:

[0010] Mix a nickel salt solution and a dispersant to obtain a nickel salt sol;

[0011] Mix HZSM-5 molecular sieve and the nickel salt sol, then add a precipitant, heat and filter, and reduce the obtained solid in a hydrogen atmosphere to obtain a catalyst precursor; the mass ratio of nickel in the nickel salt solution to the mass of the HZSM-5 molecular sieve is (0.1-10):100;

[0012] Immerse the catalyst precursor in a palladium salt solution for ion exchange, and dry to obtain the coupling hydrogenation catalyst; the mass ratio of palladium in the palladium salt solution to the mass of the HZSM-5 molecular sieve is (0.005-5):100.

[0013] Preferably, the nickel salt solution is obtained by dissolving a soluble nickel salt in water; the soluble nickel salt includes at least one of nickel nitrate, nickel chloride, nickel sulfate, nickel acetate and nickel oxalate; the concentration of the nickel salt solution is 0.2-0.5 mol / L;

[0014] The dispersant includes at least one of sodium hexametaphosphate, pyrophosphate, polyvinyl alcohol, polypropylene and polyvinylpyrrolidone; the dosage ratio of the nickel salt solution to the dispersant is 60 mL:(0.1-0.5) g.

[0015] Preferably, the precipitant is at least one of sodium hydroxide, ammonia water and urea; the heating temperature is 80-100 °C, and the heating time is 0.5-4 h.

[0016] Preferably, the reduction temperature is 300-600 °C, the time is 4-6 h; the flow rate of hydrogen is 30-60 mL / min.

[0017] Preferably, the palladium salt solution is obtained by dissolving a soluble palladium salt in hydrochloric acid; the soluble palladium salt includes at least one of palladium nitrate and palladium chloride; the mass fraction of hydrochloric acid is 2-8%; the concentration of the soluble palladium salt in the palladium salt solution is 0.01-0.05 mol / L;

[0018] The ion exchange time is 12-24 h, and the temperature is room temperature.

[0019] Preferably, the molar ratio of SiO2 to Al2O3 in the HZSM-5 molecular sieve is (15-40):1.

[0020] The present invention also provides a coupling hydrogenation catalyst prepared by the preparation method described in the above solution, which is characterized in that it includes a carrier and an active component supported on the carrier. The carrier is an HZSM-5 molecular sieve; the active component includes a first active component and a second active component; the first active component is palladium; the second active component is at least one of nickel and nickel hydroxide;

[0021] The mass of the first active component is 0.005-5% of the mass of the carrier; the mass of the second active component is 0.1-10% of the mass of the carrier.

[0022] The present invention also provides the application of the coupling hydrogenation catalyst described in the above solution in the one-step synthesis of methyl isobutyl ketone from acetone.

[0023] Preferably, before the application, the coupling hydrogenation catalyst is reduced; the reduction is carried out in hydrogen; the reduction temperature is 300-600 °C, the time is 4-6 h; the flow rate of hydrogen is 30-60 mL / min.

[0024] Preferably, the reaction conditions for the one-step synthesis of methyl isobutyl ketone from acetone include: the reaction temperature is 110-180 °C, the reaction pressure is 0.1-2.5 MPa, the mass space velocity of acetone is 1-10 h -1 , and the reaction is carried out under hydrogen conditions, and the molar ratio of hydrogen to acetone is (2-20):1.

[0025] The present invention provides a preparation method of a coupling hydrogenation catalyst, which comprises the following steps: mixing a nickel salt solution and a dispersant to obtain a nickel salt sol; mixing HZSM-5 molecular sieve and the nickel salt sol, then adding a precipitant, filtering after heating, and reducing the obtained solid in a hydrogen atmosphere to obtain a catalyst precursor; the mass ratio of nickel in the nickel salt solution to the mass of the HZSM-5 molecular sieve is (0.1-10):100; impregnating the catalyst precursor in a palladium salt solution for ion exchange, and drying to obtain the coupling hydrogenation catalyst; the mass ratio of palladium in the palladium salt solution to the mass of the HZSM-5 molecular sieve is (0.005-5):100. The present invention first loads the active component Ni on the HZSM-5 molecular sieve through precipitation and reduction, and then loads Pd on the HZSM-5 molecular sieve by the ion exchange method, and allows the noble metal Pd with stronger hydrogen dissociation ability to be loaded on the base metal Ni providing the hydrogenation site by the exchange method. This catalyst structure can dissociate hydrogen into hydrogen atoms on the noble metal first, and the hydrogen atoms reach the surface of the base metal providing the hydrogenation site by the way of overflow and react with the acetone molecules bound on the base metal to carry out hydrogenation reaction. The preparation method of the present invention can avoid the noble metal with less content being covered by the base metal, thereby reducing the loading amount of the noble metal and lowering the catalyst cost.

[0026] The coupling hydrogenation catalyst prepared by the present invention can simultaneously achieve high conversion rate and high selectivity, the yield of the target product is relatively high, and the reaction conditions are mild and the applicable process conditions are wide. The results of the examples show that the catalyst of the present invention has relatively high conversion rate and selectivity under the conditions of reaction temperature of 130-170 °C and hydrogen pressure of 0.1-1 MPa. Under the conditions of reaction temperature of 130 °C and hydrogen pressure of 1 MPa, the acetone conversion rate can reach 77.3%, and the selectivity of methyl isobutyl ketone can reach 94.4%. Detailed implementation mode

[0027] The present invention provides a preparation method of a coupling hydrogenation catalyst, which comprises the following steps:

[0028] Mixing a nickel salt solution and a dispersant to obtain a nickel salt sol;

[0029] Mixing HZSM-5 molecular sieve and the nickel salt sol, then adding a precipitant, filtering after heating, and reducing the obtained solid in a hydrogen atmosphere to obtain a catalyst precursor; the mass ratio of nickel in the nickel salt solution to the mass of the HZSM-5 molecular sieve is (0.1-10):100;

[0030] Impregnating the catalyst precursor in a palladium salt solution for ion exchange, and drying to obtain the coupling hydrogenation catalyst; the mass ratio of palladium in the palladium salt solution to the mass of the HZSM-5 molecular sieve is (0.005-5):100.

[0031] In the present invention, a nickel salt solution and a dispersant are mixed to obtain a nickel salt sol. In the present invention, the nickel salt solution is preferably obtained by dissolving a soluble salt of nickel in water; the soluble salt of nickel preferably includes at least one of nickel nitrate, nickel chloride, nickel sulfate, nickel acetate, and nickel oxalate; the concentration of the nickel salt solution is preferably 0.2 to 0.5 mol / L, more preferably 0.3 to 0.4 mol / L; the dispersant preferably includes at least one of sodium hexametaphosphate, pyrophosphate, polyvinyl alcohol, polypropylene, and polyvinylpyrrolidone, more preferably polyvinylpyrrolidone, and the polyvinylpyrrolidone is preferably K-30; the dispersant can uniformly disperse nickel nanoparticles in the system; the dosage ratio of the nickel salt solution to the dispersant is preferably 60 mL:(0.1 to 0.5) g, more preferably 60 mL:0.2 g. In a specific embodiment of the present invention, it is preferred to mix the nickel salt solution and the dispersant, and then stir at room temperature for 20 to 60 min to fully dissolve the dispersant to obtain a nickel salt sol.

[0032] After obtaining the nickel salt sol, in the present invention, HZSM-5 zeolite and the nickel salt sol are mixed, then a precipitating agent is added, filtered after heating, and the obtained solid is reduced in a hydrogen atmosphere to obtain a catalyst precursor. In the present invention, the mass ratio of nickel in the nickel salt solution to the mass of the HZSM-5 zeolite is preferably (0.1 to 10):100, more preferably (0.5 to 5):100; the molar ratio of SiO2 to Al2O3 in the HZSM-5 zeolite is preferably (15 to 40):1, more preferably (20 to 30):1; the HZSM-5 zeolite and the nickel salt sol are preferably mixed in a ratio of equal-volume impregnation.

[0033] In the present invention, the precipitating agent is preferably at least one of sodium hydroxide, ammonia water and urea, more preferably urea; the precipitating agent is preferably used in the form of an aqueous solution, and the concentration of the precipitating agent aqueous solution is preferably 0.1 - 2.0 mol / L; in the present invention, HZSM-5 molecular sieve is preferably added to the nickel salt sol, and then the precipitating agent aqueous solution is added dropwise under stirring conditions. After the addition is completed, stirring is continued for 20 - 60 min, preferably for 30 - 45 min, and then the mixed system is transferred to a heating device for heating; the volume ratio of the nickel salt solution to the precipitating agent aqueous solvent is preferably 1:1; the heating temperature is preferably 80 - 100 °C, more preferably 90 - 95 °C, and the heating time is preferably 0.5 - 4 h, more preferably 1 - 3 h; in a specific embodiment of the present invention, the heating is preferably carried out under reflux conditions, and when the pH value of the mixed system reaches 7 - 8, heating is preferably stopped; the heating device is preferably an oil bath device or a hot water device, more preferably an oil bath device; after the heating is completed, the container containing the mixed system is preferably placed in cold water and quickly cooled to room temperature, and then filtered, and the obtained solid is washed and dried; the washing solvent is preferably deionized water, and the residual chloride ions are removed by washing; the drying temperature is preferably 100 - 120 °C, and the time is preferably 10 - 12 h.

[0034] In the present invention, the reduction temperature is 300 - 600 °C, more preferably 400 - 550 °C, the reduction time is 4 - 6 h, and the hydrogen flow rate is 30 - 60 mL / min, more preferably 40 - 50 mL / min; in the present invention, Ni(OH)₂ present in the catalyst is reduced to Ni by reduction, and at the same time, the residual dispersant can be removed.

[0035] After obtaining the catalyst precursor, in the present invention, the catalyst precursor is impregnated in a palladium salt solution for ion exchange, and the coupled hydrogenation catalyst is obtained after drying. In the present invention, the palladium salt solution is preferably prepared by dissolving a soluble salt of palladium in hydrochloric acid; the soluble salt of palladium preferably includes at least one of palladium nitrate and palladium chloride, more preferably palladium chloride; the mass fraction of hydrochloric acid is preferably 2 - 8%, more preferably 5%; the concentration of the soluble salt of palladium in the palladium salt solution is preferably 0.01 - 0.05 mol / L, more preferably 0.02 - 0.04 mol / L; the mass ratio of the palladium in the palladium salt solution to the mass of the HZSM-5 molecular sieve is (0.005 - 5):100, preferably (0.02 - 2):100, more preferably 0.02:100, 0.2:100, 0.5:100, 0.3:100, 1:100 or 2:100; the impregnation is preferably equal-volume impregnation; the ion exchange time is preferably 12 - 24 h, and the temperature is preferably room temperature; the ion exchange is preferably carried out under stirring conditions; during the ion exchange process, Pd ions (Pd2+ ) and Ni in the catalyst precursor (Ni 0 ) are replaced; after the ion replacement is completed, the remaining liquid is removed, and the obtained product is dried. The drying temperature is preferably 100-120°C, and the time is preferably 10-12h.

[0036] The present invention also provides a coupling hydrogenation catalyst prepared by the preparation method described in the above solution, including a carrier and an active component supported on the carrier. The carrier is HZSM-5 molecular sieve; the active component includes a first active component and a second active component; the first active component is palladium; the second active component is at least one of nickel and nickel hydroxide;

[0037] The mass of the first active component is 0.005-5% of the mass of the carrier, preferably 0.02-2%; the mass of the second active component is 0.1-10% of the mass of the carrier, preferably 0.2-5%.

[0038] The present invention also provides the application of the coupling hydrogenation catalyst described in the above solution in the one-step synthesis of methyl isobutyl ketone from acetone. In the present invention, before the application, the coupling hydrogenation catalyst is reduced; the reduction is preferably carried out in hydrogen; the reduction temperature is preferably 300-600°C, more preferably 400-550°C, and the heating rate to the reduction temperature is preferably 1-5°C / min, more preferably 2-3°C / min; the reduction time is preferably 4-6h; the flow rate of hydrogen is preferably 30-60 mL / min, more preferably 40-50 mL / min; after the reduction is completed, the present invention preferably switches to a nitrogen atmosphere and cools to room temperature; oxidation may occur during the storage and transportation of the catalyst. By reducing the catalyst before use in the present invention, it can ensure that both Pd and Ni in the coupling hydrogenation catalyst exist in the elemental form.

[0039] In the present invention, the reaction conditions for the one-step synthesis of methyl isobutyl ketone from acetone preferably include: the reaction temperature is 110-180°C, preferably 120-160°C, the reaction pressure is 0.1-2.5 MPa, preferably 0.1-1.5 MPa, and the mass space velocity of acetone is 1-10h -1 , preferably 1-5h -1 , the reaction is carried out under hydrogen conditions, and the molar ratio of hydrogen to acetone is preferably (2-20):1, more preferably (2-10):1.

[0040] In a specific embodiment of the present invention, preferably, quartz sand and the coupling hydrogenation catalyst are filled into the reaction tube of a fixed-bed reactor, and then nitrogen is introduced into the fixed-bed reactor for purging to remove the original air in the reaction tube. After that, acetone and hydrogen are introduced for reaction, and the obtained product is sent to a condensation tank for condensation and collection; the volume ratio of the quartz sand to the coupling hydrogenation catalyst is preferably (1 - 5):1, more preferably (2 - 3):1.

[0041] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0042] Example 1

[0043] Add 1.5 mL of nickel nitrate hexahydrate solution with a concentration of 0.2278 mol / L to a round-bottom flask, and make up to 60 mL with deionized water. At the same time, add 0.2 g of polyvinylpyrrolidone K-30, and stir at room temperature for 30 min. Add 4 g of HZSM-5 zeolite molecular sieve (the molar ratio of SiO2 to Al2O3 is 15) to the round-bottom flask, and while stirring, slowly add 60 mL of 1.43 mol / L urea aqueous solution to the round-bottom flask at a constant speed. After continuing to stir for 30 min, transfer the round-bottom flask to an oil bath and heat under reflux at 90 °C for 1 h. Stop heating when the pH value of the mixed system reaches 7, and quickly cool it to room temperature in cold water. Filter and wash the mixed system to remove chloride ions, then send it to an oven and dry it at 100 °C for 10 h. After that, reduce the obtained solid in a hydrogen atmosphere at 400 °C for 4 h to obtain a catalyst precursor.

[0044] Take 3.34 mL of palladium dichloride solution with a concentration of 0.0225 mol / L, make up to 60 mL with deionized water, impregnate it with the catalyst precursor in an equal volume, and stir at room temperature for 12 h for ion exchange. After the ion exchange is completed, filter the catalyst to remove the remaining liquid, and send it to an oven and dry it at 100 °C for 10 h to obtain a coupling hydrogenation catalyst.

[0045] Before use, reduce the coupling hydrogenation catalyst by 99.99% high-purity hydrogen in a programmed temperature rise manner. The flow rate of hydrogen is 45 mL / min, the heating rate is 3 °C / min, the reduction temperature is 400 °C, the reduction holding time is 5 h, and the catalyst obtained after cooling is denoted as C1.

[0046] Example 2

[0047] Add 1.5 mL of nickel nitrate hexahydrate solution with a concentration of 0.2278 mol / L to a round-bottom flask, and dilute it to 60 mL with deionized water. At the same time, add 0.3 g of polyvinylpyrrolidone K-30 and stir at room temperature for 35 min. Add 4 g of HZSM-5 zeolite molecular sieve (the molar ratio of SiO2 to Al2O3 is 25) to the round-bottom flask, and while stirring, slowly add 60 mL of 1.43 mol / L urea aqueous solution to the round-bottom flask at a constant speed. After continuing to stir for 35 min, transfer the round-bottom flask to an oil bath and heat under reflux at 95 °C for 1 h. Stop heating when the pH value of the mixed system reaches 8, and quickly cool it to room temperature in cold water. Filter and wash the mixed system to remove chloride ions, then send it to an oven and dry it at 110 °C for 11 h. After that, reduce the obtained solid in a hydrogen atmosphere at 500 °C for 4 h to obtain a catalyst precursor.

[0048] Take 8.35 mL of palladium chloride solution with a concentration of 0.0225 mol / L, dilute it to 60 mL with deionized water, impregnate it with the catalyst precursor in an equal volume, and stir at room temperature for 14 h for ion exchange. After the ion exchange is completed, filter the catalyst to remove the remaining liquid, and send it to an oven and dry it at 100 °C for 11 h to obtain a coupling hydrogenation catalyst.

[0049] Before use, reduce the catalyst by high-purity hydrogen with a purity of 99.99% in a programmed heating manner. The flow rate of hydrogen is 50 mL / min, the heating rate is 2 °C / min, the reduction temperature is 500 °C, and the reduction holding time is 4 h. After cooling, the obtained catalyst is denoted as C2.

[0050] Example 3

[0051] Add 3 mL of nickel nitrate hexahydrate solution with a concentration of 0.2278 mol / L to a round-bottom flask, and dilute it to 60 mL with deionized water. At the same time, add 0.4 g of polyvinylpyrrolidone K-30 and stir at room temperature for 40 min. Add 4 g of HZSM-5 zeolite molecular sieve (the molar ratio of SiO2 to Al2O3 is 40) to the round-bottom flask, and while stirring, slowly add 60 mL of 1.43 mol / L urea aqueous solution to the round-bottom flask at a constant speed. After continuing to stir for 40 min, transfer the round-bottom flask to an oil bath and heat under reflux at 90 °C for 2 h. Stop heating when the pH value of the mixed system reaches 7, and quickly cool it to room temperature in cold water. Filter and wash the mixed system to remove chloride ions, then send it to an oven and dry it at 120 °C for 12 h. After that, reduce the obtained solid in a hydrogen atmosphere at 400 °C for 5 h to obtain a catalyst precursor.

[0052] Take 0.33 mL of palladium dichloride solution with a concentration of 0.0225 mol / L, dilute it to 60 mL with deionized water, impregnate it in equal volume with the catalyst precursor, and stir at room temperature for 16 h for ion exchange. After the ion exchange is completed, the catalyst is filtered by suction to remove the remaining liquid, and then sent to an oven to be dried at 120 °C for 10 h to obtain the coupling hydrogenation catalyst.

[0053] Before use, reduce the catalyst by high-purity hydrogen with a purity of 99.99% in a programmed heating manner. The flow rate of hydrogen is 40 mL / min, the heating rate is 2 °C / min, the reduction temperature is 450 °C, the reduction holding time is 6 h, and the catalyst obtained after cooling is labeled as C3.

[0054] Example 4

[0055] Add 3 mL of nickel nitrate hexahydrate solution with a concentration of 0.2278 mol / L to a round-bottom flask, dilute it to 60 mL with deionized water, and add 0.2 g of polyvinylpyrrolidone K-30 at the same time. Stir at room temperature for 45 min. Add 4 g of HZSM-5 zeolite molecular sieve (the molar ratio of SiO2 and Al2O3 is 25) to the round-bottom flask, and slowly drip 60 mL of 1.43 mol / L urea aqueous solution into the round-bottom flask while stirring. After continuing to stir for 45 min, transfer the round-bottom flask to an oil bath and heat it under reflux at 95 °C for 3 h. Stop heating when the pH value of the sol reaches 8, and quickly cool it to room temperature in cold water. Filter the sol by suction, wash it to remove chloride ions, then send it to an oven to be dried at 100 °C for 10 h. Then reduce the obtained solid in a hydrogen atmosphere at 500 °C for 5 h to obtain the catalyst precursor.

[0056] Take 5 mL of palladium dichloride solution with a concentration of 0.0225 mol / L, dilute it to 60 mL with deionized water, impregnate it in equal volume with the catalyst precursor, and stir at room temperature for 18 h for ion exchange. After the ion exchange is completed, the catalyst is filtered by suction to remove the remaining liquid, and then sent to an oven to be dried at 110 °C for 12 h to obtain the coupling hydrogenation catalyst.

[0057] Before use, reduce the catalyst by high-purity hydrogen with a purity of 99.99% in a programmed heating manner. The flow rate of hydrogen is 45 mL / min, the heating rate is 3 °C / min, the reduction temperature is 550 °C, the reduction holding time is 4 h, and the catalyst obtained after cooling is labeled as C4.

[0058] Example 5

[0059] Add 6 mL of nickel nitrate hexahydrate solution with a concentration of 0.2278 mol / L to a round-bottom flask, and dilute it to 60 mL with deionized water. At the same time, add 0.3 g of polyvinylpyrrolidone K-30, and stir at room temperature for 30 min. Add 4 g of HZSM-5 zeolite molecular sieve (molar ratio of SiO2 to Al2O3 is 40) to the round-bottom flask, and slowly add 60 mL of 1.43 mol / L urea aqueous solution dropwise to the round-bottom flask while stirring. After continuing to stir for 30 min, transfer the round-bottom flask to an oil bath and heat under reflux at 90 °C for 2 h. Stop heating when the pH value of the sol reaches 7, and quickly cool it to room temperature in cold water. Filter and wash the sol to remove chloride ions, then send it to an oven and dry it at 110 °C for 11 h. Then, reduce the obtained solid in a hydrogen atmosphere at 450 °C for 4 h to obtain the catalyst precursor.

[0060] Take 16.7 mL of palladium chloride solution with a concentration of 0.0225 mol / L, dilute it to 60 mL with deionized water, impregnate it with the catalyst precursor in an equal volume, and stir at room temperature for 20 h for ion exchange. After completing the ion exchange, filter the catalyst to remove the remaining liquid, and send it to an oven and dry it at 100 °C for 12 h to obtain the coupling hydrogenation catalyst.

[0061] Before use, reduce the catalyst by high-purity hydrogen with a purity of 99.99% in a programmed heating manner. The flow rate of hydrogen is 50 mL / min, the heating rate is 2 °C / min, the reduction temperature is 400 °C, the reduction holding time is 6 h, and the catalyst obtained after cooling is marked as C5.

[0062] Example 6

[0063] Add 6 mL of nickel nitrate hexahydrate solution with a concentration of 0.2278 mol / L to a round-bottom flask, and dilute it to 60 mL with deionized water. At the same time, add 0.4 g of polyvinylpyrrolidone K-30, and stir at room temperature for 40 min. Add 4 g of HZSM-5 zeolite molecular sieve (molar ratio of SiO2 to Al2O3 is 15) to the round-bottom flask, and slowly add 60 mL of 1.43 mol / L urea aqueous solution dropwise to the round-bottom flask while stirring. After continuing to stir for 40 min, transfer the round-bottom flask to an oil bath and heat under reflux at 95 °C for 3 h. Stop heating when the pH value of the mixed system reaches 8, and quickly cool it to room temperature in cold water. Filter and wash the mixed system to remove chloride ions, then send it to an oven and dry it at 120 °C for 12 h. Then, reduce the obtained solid in a hydrogen atmosphere at 450 °C for 5 h to obtain the catalyst precursor.

[0064] Take 33.4 mL of palladium dichloride solution with a concentration of 0.0225 mol / L, dilute it to 60 mL with deionized water, impregnate it with the catalyst precursor in an equal volume, and stir at room temperature for 22 h for ion exchange. After completing the ion exchange, filter the catalyst to remove the remaining liquid, and send it to an oven to dry at 120 °C for 12 h to obtain the coupling hydrogenation catalyst.

[0065] Before use, reduce the catalyst by 99.99% high-purity hydrogen in a programmed heating manner. The flow rate of hydrogen is 40 mL / min, the heating rate is 3 °C / min, the reduction temperature is 500 °C, the reduction holding time is 5 h, and the catalyst obtained after cooling is labeled as C6.

[0066] Comparative Example 1

[0067] Add 1.5 mL of nickel nitrate hexahydrate solution with a concentration of 0.2278 mol / L to a round-bottom flask, dilute it to 60 mL with deionized water, and add 0.3 g of polyvinylpyrrolidone K-30 at the same time. Stir at room temperature for 35 min. Add 4 g of γ-alumina to the round-bottom flask, and while stirring, slowly add 60 mL of 1.43 mol / L aqueous urea solution to the round-bottom flask at a constant speed. After continuing to stir for 35 min, transfer the round-bottom flask to an oil bath and heat it under reflux at 95 °C for 1 h. Stop heating when the pH value of the mixed system reaches 8, and quickly cool it to room temperature in cold water. Filter and wash the mixed system to remove chloride ions, then send it to an oven to dry at 110 °C for 11 h. Then reduce the obtained solid in a hydrogen atmosphere at 500 °C for 4 h to obtain the catalyst precursor.

[0068] Take 8.35 mL of palladium dichloride solution with a concentration of 0.0225 mol / L, dilute it to 60 mL with deionized water, impregnate it with the catalyst precursor in an equal volume, and stir at room temperature for 14 h for ion exchange. After completing the ion exchange, filter the catalyst to remove the remaining liquid, and send it to an oven to dry at 100 °C for 11 h to obtain the coupling hydrogenation catalyst.

[0069] Before use, reduce the catalyst by 99.99% high-purity hydrogen in a programmed heating manner. The flow rate of hydrogen is 50 mL / min, the heating rate is 2 °C / min, the reduction temperature is 500 °C, the reduction holding time is 4 h, and the catalyst obtained after cooling is labeled as D1.

[0070] Comparative Example 2

[0071] Add 1.5 mL of nickel nitrate hexahydrate solution with a concentration of 0.2278 mol / L to a round-bottom flask, and dilute it to 60 mL with deionized water. At the same time, add 0.3 g of polyvinylpyrrolidone K-30, and stir for 35 min at room temperature. Add 4 g of HZSM-5 zeolite molecular sieve (the molar ratio of SiO2 to Al2O3 is 15) to the round-bottom flask, and while stirring, slowly add 60 mL of 1.43 mol / L urea aqueous solution to the round-bottom flask at a constant speed. After continuing to stir for 35 min, transfer the round-bottom flask to an oil bath and heat it under reflux at 95 °C for 1 h. Stop heating when the pH value of the mixed system reaches 8, and quickly cool it to room temperature in cold water. Filter and wash the mixed system to remove chloride ions, then send it to an oven and dry it at 110 °C for 11 h. Then, reduce the obtained solid in a hydrogen atmosphere at 500 °C for 4 h to obtain the catalyst precursor.

[0072] Take 11.15 mL of ruthenium trichloride solution with a concentration of 0.0177 mol / L, dilute it to 60 mL with deionized water, impregnate it with the catalyst precursor in an equal volume, and stir at room temperature for 14 h for ion exchange. After completing the ion exchange, filter the catalyst to remove the remaining liquid, and send it to an oven and dry it at 100 °C for 11 h to obtain the coupling hydrogenation catalyst.

[0073] Before use, reduce the catalyst by 99.99% high-purity hydrogen in a programmed heating manner. The flow rate of hydrogen is 50 mL / min, the heating rate is 2 °C / min, the reduction temperature is 500 °C, the reduction holding time is 4 h, and the catalyst obtained after cooling is marked as D2.

[0074] Comparative Example 3

[0075] Add 8.35 mL of palladium dichloride solution with a concentration of 0.0225 mol / L to a round-bottom flask and dilute it to 60 mL with deionized water. At the same time, add 0.3 g of polyvinylpyrrolidone K-30, and stir for 35 min at room temperature. Add 4 g of HZSM-5 zeolite molecular sieve (the molar ratio of SiO2 to Al2O3 is 15) to the round-bottom flask, and while stirring, slowly add 60 mL of 1.43 mol / L urea aqueous solution to the round-bottom flask at a constant speed. After continuing to stir for 35 min, transfer the round-bottom flask to an oil bath and heat it under reflux at 95 °C for 1 h. Stop heating when the pH value of the mixed system reaches 8, and quickly cool it to room temperature in cold water. Filter and wash the mixed system to remove chloride ions, then send it to an oven and dry it at 110 °C for 11 h to obtain the coupling hydrogenation catalyst.

[0076] Before use, reduce the catalyst by 99.99% high-purity hydrogen in a programmed heating manner. The flow rate of hydrogen is 50 mL / min, the heating rate is 2 °C / min, the reduction temperature is 500 °C, the reduction holding time is 4 h, and the catalyst obtained after cooling is marked as D3.

[0077] Comparative Example 4

[0078] Add 1.5 mL of nickel nitrate hexahydrate solution with a concentration of 0.2278 mol / L into a round-bottom flask, and dilute it to 60 mL with deionized water. At the same time, add 8.35 mL of palladium dichloride solution with a concentration of 0.0225 mol / L and 0.3 g of polyvinylpyrrolidone K-30, and stir at room temperature for 35 min. Add 4 g of HZSM-5 zeolite molecular sieve (molar ratio of SiO2 to Al2O3 is 25) into the round-bottom flask, and while stirring, slowly add 60 mL of urea aqueous solution with a concentration of 1.43 mol / L to the round-bottom flask at a constant speed. After continuing to stir for 35 min, transfer the round-bottom flask to an oil bath and heat under reflux at 95 °C for 1 h. Stop heating when the pH value of the mixed system reaches 8, and quickly cool it to room temperature in cold water. Filter and wash the mixed system to remove chloride ions, and then send it to an oven to dry at 110 °C for 11 h to obtain the coupling hydrogenation catalyst.

[0079] Before use, reduce the catalyst by 99.99% high-purity hydrogen in a programmed temperature rise manner. The flow rate of hydrogen is 50 mL / min, the heating rate is 2 °C / min, the reduction temperature is 500 °C, and the reduction holding time is 4 h. After cooling, the obtained catalyst is marked as D4.

[0080] Test Example 1

[0081] Apply the catalysts prepared in Examples 1-6 and Comparative Examples 1-3 to the reaction of one-step preparation of methyl isobutyl ketone from acetone, and test their catalytic activities as follows: Pack quartz sand and the catalyst into the reaction tube of a fixed-bed reactor according to a volume ratio of 3:1, and separate the quartz sand and the catalyst with a small amount of quartz wool. Pass nitrogen into the fixed-bed reactor for purging to remove the original air in the reaction tube. Acetone is mixed with hydrogen metered by a metering pump and a gas mass flowmeter and enters the preheater. The acetone is vaporized and then enters the reactor, flowing through the catalyst bed layer, and a series of reactions such as condensation, dehydration, and hydrogenation occur under the catalytic action of the catalyst. The reaction conditions are: reaction temperature 130 °C, reaction pressure 1.0 MPa, feed mass space velocity 1 h -1 -1, and the molar ratio of hydrogen to acetone is 5:1. The product containing methyl isobutyl ketone is sent to a condensation tank for condensation collection and test analysis, and the evaluation results are shown in Table 1.

[0082] Table 1 Catalyst Evaluation Results in Examples and Comparative Examples

[0083]

[0084] As can be seen from the data in Table 1, the catalyst prepared by the present invention has excellent catalytic performance for the one-step preparation of methyl isobutyl ketone from acetone. This catalyst can achieve both high activity and high selectivity, and the yield of methyl isobutyl ketone is higher than that of the catalysts commonly used in this reaction at present, having high industrial application value. The catalyst carriers or active components used in Comparative Examples 1-3 are different from those in the Examples, and the acetone conversion rate of the obtained catalysts drops significantly, and the selectivity of methyl isobutyl ketone in D2 is also low; in Comparative Example 4, Ni and Pd are loaded simultaneously by the deposition-precipitation method, and the acetone conversion rate of the obtained catalyst is also low.

[0085] Test Example 2

[0086] The reduced catalyst prepared in Example 2 was loaded into a fixed-bed reactor with a loading amount of 1 g, and the performance of the catalyst under different process conditions was tested. The test method was the same as that in Test Example 1. The specific process conditions and test results are shown in Table 2.

[0087] Table 2 Catalytic Performance under Different Processes

[0088]

[0089] As can be seen from the data in Table 2, the coupling hydrogenation catalyst prepared by the present invention is suitable for a wide range of process conditions. At a temperature of 130-170 °C, a pressure of 0.1-1 MPa, and a mass space velocity of acetone of 1-5 h -1 , it has high acetone conversion rate and selectivity.

[0090] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. The application of a coupled hydrogenation catalyst in the one-step synthesis of methyl isobutyl ketone from acetone, characterized in that, The preparation method of the coupled hydrogenation catalyst comprises the following steps: Mix a nickel salt solution and a dispersant to obtain a nickel salt sol; Mix the HZSM-5 molecular sieve and the nickel salt sol, then add a precipitant, filter after heating, and reduce the obtained solid in a hydrogen atmosphere to obtain a catalyst precursor; the mass ratio of nickel in the nickel salt solution to the mass of the HZSM-5 molecular sieve is (0.1-10):100; the reduction temperature is 300-600 °C, the time is 4-6 h; the flow rate of the hydrogen is 30-60 mL / min; Immerse the catalyst precursor in a palladium salt solution for ion exchange, and obtain the coupled hydrogenation catalyst after drying; the mass ratio of palladium in the palladium salt solution to the mass of the HZSM-5 molecular sieve is (0.005-5):

100.

2. The application according to claim 1, characterized in that, The nickel salt solution is obtained by dissolving a soluble nickel salt in water; the soluble nickel salt includes at least one of nickel nitrate, nickel chloride, nickel sulfate, nickel acetate and nickel oxalate; The concentration of the nickel salt solution is 0.2-0.5 mol / L; The dispersant includes at least one of sodium hexametaphosphate, pyrophosphate, polyvinyl alcohol, polypropylene and polyvinylpyrrolidone; the dosage ratio of the nickel salt solution to the dispersant is 60 mL:(0.1-0.5) g.

3. The application according to claim 1, characterized in that, The precipitant is at least one of sodium hydroxide, ammonia water and urea; the heating temperature is 80-100 °C, and the heating time is 0.5-4 h.

4. The application according to claim 1, characterized in that, The palladium salt solution is obtained by dissolving a soluble palladium salt in hydrochloric acid; the soluble palladium salt includes at least one of palladium nitrate and palladium chloride; the mass fraction of the hydrochloric acid is 2-8%; the concentration of the soluble palladium salt in the palladium salt solution is 0.01-0.05 mol / L; the ion exchange time is 12-24 h, and the temperature is room temperature.

5. The application according to claim 1, characterized in that, The molar ratio of SiO2 to Al2O3 in the HZSM-5 molecular sieve is (15-40):

1.

6. The application according to claim 1, characterized in that, The coupled hydrogenation catalyst includes a carrier and active components supported on the carrier, the carrier is the HZSM-5 molecular sieve; the active components include a first active component and a second active component; the first active component is palladium; the second active component is at least one of nickel and nickel hydroxide; The mass of the first active component is 0.005-5% of the mass of the carrier; the mass of the second active component is 0.1-10% of the mass of the carrier.

7. The application according to claim 1, characterized in that, Before the application, the coupled hydrogenation catalyst is reduced; the reduction is carried out in hydrogen; the reduction temperature is 300-600 °C, the time is 4-6 h; the flow rate of the hydrogen is 30-60 mL / min.

8. The application according to claim 1, characterized in that, The reaction conditions for the one-step synthesis of methyl isobutyl ketone from acetone include: the reaction temperature is 110-180 °C, the reaction pressure is 0.1-2.5 MPa, and the mass space velocity of acetone is 1-10 h -1 , the reaction is carried out under hydrogen conditions, and the molar ratio of hydrogen to acetone is (2-20):1.

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