Method for synthesizing methyl isoamyl ketone by one-step method

Abstract

The invention relates to a method for synthesizing methyl isoamyl ketone by a one-step method. The method comprises the following steps: mixing acetone and isobutyraldehyde, preheating through a fixed bed reactor filled with a catalyst, reacting with hydrogen in a fixed bed, carrying out aldol condensation, dehydration and hydrogenation reactions, cooling and collecting effluent steam, and thus obtaining a solution of a methyl isoamyl ketone product; the catalyst is a composite metal oxide supported palladium catalyst, the general formula is Pd / CexMyOz, M comprises one of Zr, Al, Mg, Ti and Mn, Pd is used as a hydrogenation active component, and CexMyOz is used as a catalyst carrier and provides an acid / alkali active site. The method has the advantages of simple process, convenience in catalyst preparation, high catalytic activity, high methyl isoamyl ketone selectivity and the like, and has a good industrial application prospect.

Description

Technical Field

[0001] The invention belongs to the field of preparation of methyl isoamyl ketone, and particularly relates to a method for continuously preparing methyl isoamyl ketone by utilizing acetone and isobutyraldehyde. Background Art

[0002] Methyl isoamyl ketone (MIAK) is a colorless, transparent liquid with strong solubility, low and stable volatilization rate. It is usually used as a high-solid coating, such as polyurethane paint resin, to improve the advection performance and fullness of the paint film, and to give a gloss similar to the projection effect. Adding a certain amount can significantly improve the performance of the paint film. It can also be used to synthesize acrylic resins, using the solvent capacity of methyl isoamyl ketone to improve the compatibility between resins. At the same time, methyl isoamyl ketone is also the raw material for synthesizing 7PPD antioxidants. 7PPD antioxidants have excellent resistance to heat aging and ozone oxidation, and have good protection against weather aging and fatigue aging. Compared with the previous generation 6PPD antioxidant, it has better performance and conforms to the concept of green production. At present, the industrial method for synthesizing methyl isoamyl ketone at home and abroad mainly uses acetone and isobutyraldehyde as raw materials. It can be synthesized in one step or in two steps by condensation dehydration and hydrogenation.

[0003] At present, acetone and isobutyraldehyde are mainly used as raw materials for the synthesis of methyl isoamyl ketone at home and abroad. Patent CN202011635892.4 uses acetone and isobutyraldehyde as raw materials to synthesize MIAK in two steps under the action of phosphonic acid resin and Pd / C catalyst. This method faces the problem of purifying the intermediate product 5-methyl-3-ene-2-hexanone. If it is purified first and then hydrogenated, there are disadvantages such as complex operation process and high energy consumption; if it is directly hydrogenated without purification, it will cause many by-products and high raw material consumption. Problems. Another process is to mix acetone, isobutyraldehyde and hydrogen, and complete the aldol condensation (mainly base catalysis), dehydration (acid catalysis) and hydrogenation (metal catalysis) in one step on a multifunctional catalyst. Patent CN202011199013.8 improves the method of patent CN202011635892.4, and synthesizes MIAK by a one-step method. The isobutyraldehyde conversion rate reaches up to 45.3%, and the MIAK selectivity is 57.2%. Patent US20040122261A1 uses Pd / C as a catalyst, and mixes the homogeneous base NaOH with the raw materials and then enters the reactor to synthesize MIAK. The isobutyraldehyde conversion rate is 99.44%, and the MIAK yield is 50.51%. Although the raw material conversion rate is high at this time, there are problems with NaOH separation and corrosion of equipment. At the same time, since both raw materials contain α-H atoms, self-condensation and cross-condensation may occur during the condensation process, so multiple condensation reactions will occur in the system, resulting in an increase in by-products and a reduction in the selectivity of the target product. Therefore, in view of the current state of the art, the development of a multifunctional catalyst with high activity, high stability and high selectivity is the key to synthesizing MIAK.

[0004] Through a large amount of preliminary literature research and experimental exploration, we found that by using palladium as the hydrogenation active component and adjusting the composition of the metal oxide carrier, we can obtain a catalytic material for the one-step synthesis of methyl isoamyl ketone from acetone and isobutyraldehyde with high efficiency. Summary of the invention

[0005] The purpose of the present invention is to develop a heterogeneous multifunctional catalyst with high thermal stability, multiple acid-base active sites and reusable properties to realize a method for continuously preparing methyl isoamyl ketone. Compared with other preparation methods, this method has the advantages of simple operation flow, stable catalyst performance, high raw material conversion rate, high target product selectivity, low raw material cost, and little environmental pollution.

[0006] The present invention provides a one-step method for synthesizing methyl isoamyl ketone, comprising the following contents: Acetone, isobutyraldehyde and hydrogen are mixed and passed through a reactor containing a multifunctional catalyst. After preheating, a gas phase reaction is carried out in a fixed bed. After aldol condensation, dehydration and hydrogenation reactions, the outflowing steam is cooled and collected to obtain a solution of a methyl isoamyl ketone product. The catalyst is a composite metal oxide supported palladium catalyst with a general formula of Pd / Ce x M y O z , M includes one of Zr, Al, Mg, Ti, and Mn metals.

[0007] The composite oxide catalyst carrier in the catalyst of the present invention uses cerium as the active center, and cerium oxide is modified by adding other metals. The prepared composite metal oxide can adjust the surface acidity and alkalinity of the catalyst, and also serves as a carrier of the composite metal oxide supported palladium catalyst. The catalytic activity of the catalyst is improved, and the conversion rate of the raw material and the selectivity of the target product are further improved.

[0008] Metal Pd is used as the hydrogenation active component, Ce x M y O z As a catalyst carrier and providing acid / base components in the reaction, M includes one of Zr, Al, Mg, Ti, and Mn metals.

[0009] The present invention also provides the composite metal oxide supported palladium catalyst, which is prepared according to the following method: S1: According to the type and composition ratio of the catalyst metal, the general formula is Pd / Ce according to the molar percentage. x M y O z A mixed solution of metal salts corresponding to the metal elements of the catalyst carrier; S2: Under room temperature, the corresponding metal salt mixed solution and ammonia solution are co-precipitated to prepare the catalyst, the precipitation process is fully stirred, the pH value is adjusted to 8-11, aged at room temperature, filtered, washed, dried and calcined to obtain the corresponding Ce x M y O z Carrier; S3: After dissolving palladium chloride in deionized water, add the carrier Ce x M y O z The catalyst was impregnated and allowed to stand for 8-12 h, and then dried and calcined to obtain a precursor, which was activated in a H2 atmosphere to obtain a supported palladium catalyst.

[0010] Furthermore, the Pd / Ce x M y O z The mass percentage of Pd in ​​the catalyst is 0.05-0.5%, and the carrier Ce x M y O z Here, x:y ranges from 0.3 to 3, and z is the atomic ratio of oxygen required to satisfy the valence of each element.

[0011] Furthermore, in the preparation step S1 of the composite oxide supported palladium catalyst of the present invention, the corresponding metal salt is dissolved in deionized water to form a mixed solution with a concentration of 0.2-0.8 mol / L, and the metal salt is selected from one of sulfate, hydrochloride, nitrate and carbonate.

[0012] Furthermore, in the preparation step S2 of the composite oxide supported palladium catalyst of the present invention, the corresponding Ce x M y O z The carrier is aged for 10-15 h, dried at 100-150 °C, and calcined at 300-600 °C for 4-8 h.

[0013] Furthermore, in the preparation step S3 of the composite oxide supported palladium catalyst of the present invention, the corresponding Ce x M y O z After the carrier is impregnated with Pd salt solution, it is dried at 60-100 °C, calcined at 400-700 °C for 3-7 h to obtain a precursor, and the precursor is activated in a H2 atmosphere at 100-400 °C for 3-7 h.

[0014] Furthermore, the molar ratio of the raw materials acetone to isobutyraldehyde described in the present invention is 5.5-8.5.

[0015] Furthermore, the liquid hourly space velocity of the raw material of the present invention is 2.0-5.0 h -1 Too high a space velocity will lead to incomplete condensation hydrogenation reaction of acetone and isobutyraldehyde, while too low a space velocity will lead to self-condensation of the raw materials and excessive condensation of the products and the raw materials, affecting the selectivity of the reaction and reducing the yield of methyl isoamyl ketone.

[0016] Furthermore, the molar ratio of hydrogen to isobutyraldehyde in the present invention is 2.13-10.67. Excessive hydrogen can easily lead to hydrogenation of carbonyl groups in the isobutyraldehyde raw material and product structure, reducing the selectivity of the reaction.

[0017] Furthermore, the reaction temperature of the present invention is 150-200° C. Too high a temperature will lead to excessive condensation of the product and the raw material, while too low a temperature will lead to incomplete reaction of acetone, isobutyraldehyde and hydrogen, resulting in the generation of by-products.

[0018] Furthermore, the reaction pressure of the present invention is 1.0-3.0 MPa. Too low a reaction pressure will affect the efficiency of the hydrogenation reaction, while too high a reaction pressure will lead to hydrogenation of the carbonyl group, generate by-products, and increase the difficulty of separating the products.

[0019] Compared with the prior art, the present invention has the following beneficial effects: 1) The present invention uses a composite metal oxide as a catalyst carrier, utilizes the acid-base adjustability of the metal oxide surface, designs a multifunctional catalytic material, realizes a one-step efficient synthesis of methyl isoamyl ketone, effectively reduces the reaction energy consumption, and the catalyst has excellent thermal stability; 2) The composite metal oxide as a multifunctional catalyst has high reaction selectivity in the aldol condensation reaction of acetone and isobutyraldehyde, which effectively avoids the condensation reaction of acetone and isobutyraldehyde themselves, improves the reaction efficiency, and simplifies the subsequent separation process. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

[0021] Examples 1-7 are the preparation of composite metal oxide supported palladium catalysts.

[0022] Example 1: 0.3% Pd / Ce 0.75 Zr 0.25 Preparation of O2 catalyst S1: According to the ratio of cerium to zirconium in the catalyst, 32.57 g of cerium nitrate hexahydrate, 10.73 g of zirconium nitrate pentahydrate and 200 mL of deionized water were added to the reactor in sequence and stirred until dissolved to prepare 0.4 mol / L Ce 0.75 Zr 0.25 Mix the metal salt solutions.

[0023] S2: 0.4 mol / L Ce at room temperature 0.75 Zr 0.25 28% ammonia solution was added to the mixed salt solution, and the addition was stopped when the pH value of the solution reached 8.5. During this process, stirring was continued, and the mixture was aged at room temperature for 12 h and then filtered. The solid was washed to neutrality and further dried at 120 °C, then ground into powder and calcined in a muffle furnace at 450 °C for 5 h to obtain Ce 0.75 Zr 0.25 O2.

[0024] S3: 30 g Ce 0.75 Zr 0.25 An equal volume of O2 was immersed in 15 mL of an aqueous solution containing 0.252 g of PdCl2 (Pd content 59.5%), ultrasonicated for 0.5 h, immersed for 12 h, dried at 90 ℃, calcined at 550 ℃ in a muffle furnace for 4 h, and catalyst particles with a particle size of 10-20 mesh were pressed and screened. The catalyst particles were programmed to heat to 300 ℃ and reduced for 4 h to obtain catalyst 1.

[0025] Example 2: 0.3% Pd / Ce 0.5 Zr 0.5 Preparation of O2 catalyst S1: According to the ratio of cerium to zirconium in the catalyst, add 21.74 g of cerium nitrate hexahydrate, 21.45 g of zirconium nitrate pentahydrate and 250 mL of deionized water to the reactor in sequence, stir until dissolved, and prepare 0.4 mol / L Ce 0.5 Zr 0.5 Mix the metal salt solutions.

[0026] S2: 0.4 mol / L Ce at room temperature 0.5 Zr 0.5 28% ammonia solution was added to the mixed salt solution, and the addition was stopped when the pH value of the solution reached 8.5. Stirring was continued during the process. After aging at room temperature for 15 h, the solid was filtered, washed to neutrality, and further dried at 120 °C, then ground into powder, and calcined in a muffle furnace at 300 °C for 8 h to obtain Ce 0.5 Zr 0.5 O2.

[0027] S3: 30 g Ce 0.5 Zr 0.5An equal volume of O2 was immersed in 15 mL of aqueous solution containing 0.252 g of PdCl2 (Pd content 59.5%), ultrasonicated for 0.5 h, immersed for 8 h, dried at 100 °C, calcined in a muffle furnace at 400 °C for 5 h, and the catalyst particles with a particle size of 10-20 mesh were pressed and screened. The catalyst particles were programmed to heat to 100 °C and reduced for 6 h to obtain catalyst 2.

[0028] Example 3: 0.3% Pd / Ce 0.25 Zr 0.75 Preparation of O2 catalyst S1: According to the ratio of cerium to zirconium in the catalyst, 32.55 g of cerium nitrate hexahydrate, 10.73 g of zirconium nitrate pentahydrate and 250 mL of deionized water were added to the reactor in sequence and stirred until dissolved to prepare 0.4 mol / L Ce 0.25 Zr 0.75 Mix the metal salt solutions.

[0029] S2: 0.4 mol / L Ce at room temperature 0.25 Zr 0.75 A 28% ammonia solution was added to the mixed salt solution, and the addition was stopped when the pH value of the solution reached 9. Stirring was continued during the process. After aging at room temperature for 10 h, the solid was filtered, washed to neutrality, and further dried at 100 °C, then ground into powder, and calcined in a muffle furnace at 600 °C for 4 h to obtain Ce 0.25 Zr 0.75 O2.

[0030] S3: 30 g Ce 0.25 Zr 0.75 An equal volume of O2 was immersed in 15 mL of aqueous solution containing 0.252 g of PdCl2 (Pd content 59.5%), ultrasonicated for 0.5 h, immersed for 8 h, dried at 60 ℃, calcined at 600 ℃ in a muffle furnace for 3 h, and catalyst particles with a particle size of 10-20 mesh were pressed and screened. The catalyst particles were programmed to heat to 200 ℃ and reduced for 7 h to obtain catalyst 3.

[0031] Example 4: 0.05% Pd / Ce 0.75 Zr 0.25 Preparation of O2 catalyst S1: According to the ratio of cerium to zirconium in the catalyst, 32.57 g of cerium nitrate hexahydrate, 10.73 g of zirconium nitrate pentahydrate and 500 mL of deionized water were added to the reactor in sequence and stirred until dissolved to prepare 0.2 mol / L Ce 0.75 Zr 0.25 Mix the metal salt solutions.

[0032] S2: 0.2 mol / L Ce at room temperature 0.75 Zr 0.25 28% ammonia solution was added to the mixed salt solution, and the addition was stopped when the pH value of the solution reached 8. Stirring was continued during the process. After aging at room temperature for 12 h, the solid was filtered, washed to neutrality, and further dried at 150 °C, then ground into powder, and calcined in a muffle furnace at 550 °C for 6 h to obtain Ce 0.75 Zr 0.25 O2.

[0033] S3: 30 g Ce 0.75 Zr 0.25 An equal volume of O2 was immersed in 15 mL of aqueous solution containing 0.042 g of PdCl2 (Pd content 59.5%), ultrasonicated for 0.5 h, immersed for 10 h, dried at 80 °C, calcined at 700 °C in a muffle furnace for 4 h, and catalyst particles with a particle size of 10-20 mesh were pressed and screened. The catalyst particles were programmed to heat to 100 °C and reduced for 7 h to obtain catalyst 4.

[0034] Example 5: 0.5% Pd / Ce 0.5 Zr 0.5 Preparation of O2 catalyst S1: According to the ratio of cerium to zirconium in the catalyst, add 21.74 g of cerium nitrate hexahydrate, 21.45 g of zirconium nitrate pentahydrate and 125 mL of deionized water to the reactor in sequence, stir until dissolved, and prepare 0.8 mol / L Ce 0.5 Zr 0.5 Mix the metal salt solutions.

[0035] S2: 0.8 mol / L Ce at room temperature 0.5 Zr 0.5 A 28% ammonia solution was added to the mixed salt solution, and the addition was stopped when the pH value of the solution reached 8.5. During this process, stirring was continued, and the mixture was aged at room temperature for 12 h before being filtered. The solid was washed to neutrality and further dried at 100 °C, then ground into powder and calcined in a muffle furnace at 400 °C for 8 h to obtain Ce 0.5 Zr 0.5 O2.

[0036] S3: 30 g Ce 0.5 Zr 0.5An equal volume of O2 was immersed in 15 mL of aqueous solution containing 0.42 g of PdCl2 (Pd content 59.5%), ultrasonicated for 0.5 h, immersed for 10 h, dried at 100 ℃, calcined at 400 ℃ in a muffle furnace for 7 h, and catalyst particles with a particle size of 10-20 mesh were pressed and screened. The catalyst particles were programmed to heat to 400 ℃ and reduced for 3 h to obtain catalyst 5.

[0037] Example 6: 0.3% Pd / Ce 0.75 Al 0.25 O 1.53 Catalyst preparation S1: According to the ratio of cerium to aluminum in the catalyst, 32.57 g of cerium nitrate hexahydrate, 9.38 g of aluminum nitrate pentahydrate and 250 mL of deionized water were added to the reactor in sequence and stirred until dissolved to prepare 0.4 mol / L Ce 0.75 Al 0.25 Mixed metal salt solution S2: At room temperature, then to 0.4 mol / L Ce 0.75 Al 0.25 A 28% ammonia solution was added to the mixed salt solution system, and the addition was stopped when the pH value of the solution reached 9. During this process, stirring was continued, and the mixture was aged at room temperature for 15 hours and then filtered. The solid was washed to neutrality and further dried at 100 °C, then ground into powder, and calcined in a muffle furnace at 500 °C for 7 hours to obtain Ce. 0.75 Al 0.25 O 1.53 .

[0038] S3: 30 g Ce 0.75 Al 0.25 O 1.53 An equal volume was immersed in 13 mL of aqueous solution containing 0.252 g of PdCl2 (Pd content 59.5%), ultrasonicated for 0.5 h, immersed for 12 h, dried at 100 °C, calcined at 550 °C in a muffle furnace for 6 h, and catalyst particles with a particle size of 10-20 mesh were pressed and screened. The catalyst particles were programmed to heat to 100 °C and reduced for 6 h to obtain catalyst 6.

[0039] Example 7: 0.3% Pd / Ce 0.75 Mn 0.25 Preparation of O2 catalyst S1: According to the ratio of cerium and manganese in the catalyst, 32.57 g of cerium nitrate hexahydrate, 4.47 g of manganese nitrate solution and 250 mL of deionized water were added to the reactor in sequence and stirred until dissolved to prepare 0.8 mol / L Ce 0.75 Mn 0.25 Mix the metal salt solutions.

[0040] S2: At room temperature, then to 0.8 mol / L Ce 0.75 Mn 0.25 A 28% ammonia solution was added to the mixed salt solution system, and the addition was stopped when the pH value of the solution reached 11. During this process, stirring was continued, and the mixture was aged at room temperature for 10 h and then filtered. After washing to neutrality, the mixture was further dried at 150 °C, and then ground into powder. The mixture was calcined in a muffle furnace at 400 °C for 6 h to obtain Ce. 0.75 Mn 0.25 O2.

[0041] S3: 30 g Ce 0.75 Mn 0.25 An equal volume of O2 was immersed in 10 mL of aqueous solution containing 0.252 g of PdCl2 (Pd content 59.5%), ultrasonicated for 0.5 h, immersed for 12 h, dried at 60 ℃, calcined at 650 ℃ in a muffle furnace for 5 h, and catalyst particles with a particle size of 10-20 mesh were pressed and screened. The catalyst particles were programmed to heat to 300 ℃ and reduced for 7 h to obtain catalyst 7.

[0042] Examples 8-18 are catalytic applications of the prepared catalyst in the one-step synthesis of methyl isoamyl ketone from acetone and isobutyraldehyde.

[0043] Example 8: 5 mL of catalyst 1 was filled in a fixed bed reactor. The fixed bed pressure was raised to 2.0 MPa under the condition of introducing hydrogen. The temperature was programmed to 180 °C. After the temperature was stabilized, a mixed raw material of acetone and isobutyraldehyde (molar ratio 5.5:1) was introduced into the vaporizer. The liquid hourly space velocity of the raw material was controlled to be 3.0 h -1 , the hydrogen space velocity was controlled to be 600 h -1 (The molar ratio of hydrogen to raw material is 4.27:1), the outflowing steam is collected after cooling and gas-liquid separation, and the collected products are quantitatively analyzed. The conversion rate of isobutyraldehyde is 78.77%, and the selectivity for methyl isoamyl ketone is 70.92%.

[0044] Example 9: 5 mL of catalyst 2 was filled in a fixed bed reactor. The fixed bed pressure was raised to 1.5 MPa under the condition of introducing hydrogen. The temperature was programmed to 190 °C. After the temperature was stabilized, a mixed raw material of acetone and isobutyraldehyde (molar ratio 6.5:1) was introduced into the vaporizer. The liquid hourly space velocity of the raw material was controlled to be 3.0 h -1 , the hydrogen space velocity was controlled to be 600 h -1 (The molar ratio of hydrogen to raw material is 4.92:1), the outflowing steam is collected after cooling and gas-liquid separation, and the collected products are quantitatively analyzed. The conversion rate of isobutyraldehyde is 65.57%, and the selectivity for methyl isoamyl ketone is 59.84%.

[0045] Example 10: 5 mL of catalyst 3 was filled in a fixed bed reactor. The fixed bed pressure was raised to 2.5 MPa under the condition of introducing hydrogen. The temperature was programmed to 170 °C. After the temperature was stabilized, a mixed raw material of acetone and isobutyraldehyde (molar ratio 7.0:1) was introduced into the vaporizer. The liquid hourly space velocity of the raw material was controlled to be 2.0 h -1 , the hydrogen space velocity was controlled to be 300 h -1 (The molar ratio of hydrogen to raw material is 3.93:1), the outflowing steam is collected after cooling and gas-liquid separation, and the collected products are quantitatively analyzed. The conversion rate of isobutyraldehyde is 43.02%, and the selectivity for methyl isoamyl ketone is 86.25%.

[0046] Example 11: 5 mL of catalyst 1 was filled in a fixed bed reactor. The fixed bed pressure was raised to 2.0 MPa under the condition of introducing hydrogen. The temperature was programmed to 150 °C. After the temperature was stabilized, a mixed raw material of acetone and isobutyraldehyde (molar ratio 5.5:1) was introduced into the vaporizer. The liquid hourly space velocity of the raw material was controlled to be 3.0 h -1 , the hydrogen space velocity was controlled to be 900 h -1 (The molar ratio of hydrogen to raw material is 6.40:1), the outflowing steam is collected after cooling and gas-liquid separation, and the collected products are quantitatively analyzed. The conversion rate of isobutyraldehyde is 53.35%, and the selectivity for methyl isoamyl ketone is 50.55%.

[0047] Example 12: 5 mL of catalyst 4 was filled in a fixed bed reactor. The fixed bed pressure was raised to 1.0 MPa under the condition of introducing hydrogen. The temperature was programmed to 200 °C. After the temperature stabilized, a mixed raw material of acetone and isobutyraldehyde (molar ratio 6.0:1) was introduced into the vaporizer. The liquid hourly space velocity of the raw material was controlled to be 4.0 h -1 , the hydrogen space velocity was controlled to be 600 h -1 (The molar ratio of hydrogen to raw material is 3.45:1), the outflowing steam is collected after cooling and gas-liquid separation, and the collected products are quantitatively analyzed. The conversion rate of isobutyraldehyde is 41.28%, and the selectivity for methyl isoamyl ketone is 83.48%.

[0048] Example 13: 5 mL of catalyst 5 was filled in a fixed bed reactor. The fixed bed pressure was raised to 3.0 MPa under the condition of introducing hydrogen. The temperature was programmed to 180 °C. After the temperature was stabilized, a mixed raw material of acetone and isobutyraldehyde (molar ratio 8.5:1) was introduced into the vaporizer. The liquid hourly space velocity of the raw material was controlled to be 5.0 h -1 , the hydrogen space velocity was controlled to be 800 h -1(The molar ratio of hydrogen to raw material is 4.99:1), the outflowing steam is collected after cooling and gas-liquid separation, and the collected products are quantitatively analyzed. The conversion rate of isobutyraldehyde is 35.04%, and the selectivity for methyl isoamyl ketone is 65.74%.

[0049] Example 14: 0049. Take 5 mL of catalyst 1 and fill it in a fixed bed reactor. Under the condition of introducing hydrogen, the fixed bed pressure is increased to 1.5 MPa, and the temperature is programmed to 160 °C. After the temperature stabilizes, a mixed raw material of acetone and isobutyraldehyde (molar ratio 5.5:1) is introduced into the vaporizer, and the liquid hourly space velocity of the raw material is controlled to be 3.0 h -1 , the hydrogen space velocity was controlled to be 1500 h -1 (The molar ratio of hydrogen to raw material is 10.67:1), the outflowing steam is collected after cooling and gas-liquid separation, and the collected products are quantitatively analyzed. The conversion rate of isobutyraldehyde is 57.89%, and the selectivity for methyl isoamyl ketone is 58.82%.

[0050] Example 15: 0050. Take 5 mL of catalyst 3 and fill it in a fixed bed reactor. Under the condition of introducing hydrogen, the fixed bed pressure is increased to 3.0 MPa, and the temperature is programmed to 200 °C. After the temperature stabilizes, a mixed raw material of acetone and isobutyraldehyde (molar ratio 6.0:1) is introduced into the vaporizer, and the liquid hourly space velocity of the raw material is controlled to be 2.0 h -1 , the hydrogen space velocity was controlled to be 800 h -1 (The molar ratio of hydrogen to raw material is 9.17:1), the outflowing steam is collected after cooling and gas-liquid separation, and the collected products are quantitatively analyzed. The conversion rate of isobutyraldehyde is 82.37%, and the selectivity for methyl isoamyl ketone is 50.91%.

[0051] Example 16: 0051. Take 5 mL of catalyst 2 and fill it in a fixed bed reactor. Under the condition of introducing hydrogen, the fixed bed pressure is increased to 1.5 MPa, and the temperature is programmed to 150 °C. After the temperature stabilizes, a mixed raw material of acetone and isobutyraldehyde (molar ratio 5.5:1) is introduced into the vaporizer, and the liquid hourly space velocity of the raw material is controlled to be 4.0 h -1 , the hydrogen space velocity was controlled to be 400 h -1 (The molar ratio of hydrogen to raw material is 2.13:1), the outflowing steam is collected after cooling and gas-liquid separation, and the collected products are quantitatively analyzed. The conversion rate of isobutyraldehyde is 52.67%, and the selectivity for methyl isoamyl ketone is 68.36%.

[0052] Example 17: 0052. Take 5 mL of catalyst 6 and fill it in a fixed bed reactor. Under the condition of introducing hydrogen, the fixed bed pressure is increased to 2.0 MPa, and the temperature is programmed to 180 °C. After the temperature stabilizes, a mixed raw material of acetone and isobutyraldehyde (molar ratio 5.5:1) is introduced into the vaporizer, and the liquid hourly space velocity of the raw material is controlled to be 4.0 h -1 , the hydrogen space velocity was controlled to be 900 h -1 (The molar ratio of hydrogen to raw material is 4.80:1), the outflowing steam is collected after cooling and gas-liquid separation, and the collected products are quantitatively analyzed. The conversion rate of isobutyraldehyde is 60.12%, and the selectivity for methyl isoamyl ketone is 51.02%.

[0053] Example 18: 0053. Take 5 mL of catalyst 7 and fill it in a fixed bed reactor. Under the condition of introducing hydrogen, the fixed bed pressure is increased to 2.0 MPa, and the temperature is programmed to 180 °C. After the temperature stabilizes, a mixed raw material of acetone and isobutyraldehyde (molar ratio 5.5:1) is introduced into the vaporizer, and the liquid hourly space velocity of the raw material is controlled to be 3.0 h -1 , the hydrogen space velocity was controlled to be 800 h -1 (The molar ratio of hydrogen to raw material is 9.30:1), the outflowing steam is collected after cooling and gas-liquid separation, and the collected products are quantitatively analyzed. The conversion rate of isobutyraldehyde is 68.24%, and the selectivity for methyl isoamyl ketone is 56.71%.

[0054] The above examples and analysis results show that the method of the present invention has a high isobutyraldehyde conversion rate, good selectivity for methyl isoamyl ketone, and less organic impurities in the product, which is conducive to simplifying the subsequent separation process. The reaction process is simple, stable and efficient.

[0055] The above examples are only used to illustrate the content of the present invention. In addition, the present invention has other embodiments. However, all technical solutions formed by equivalent replacement or equivalent deformation methods fall within the protection scope of the present invention.

Claims

1. A one-step method for synthesizing methyl isoamyl ketone, characterized in that The raw materials acetone and isobutyraldehyde are mixed and passed through a reactor equipped with a catalyst together with hydrogen, and then subjected to aldol condensation, dehydration and hydrogenation reactions. The effluent steam is cooled and collected to obtain a solution of a methyl isoamyl ketone product. The catalyst is a composite metal oxide supported palladium catalyst with a general formula of Pd / Ce x M y O z , M includes one of Zr, Al, Mg, Ti, and Mn.

2. The method according to claim 1, characterized in that The composite metal oxide supported palladium catalyst is prepared according to the following method: S1: According to the type and composition ratio of the catalyst metal, the general formula is Pd / Ce according to the molar percentage. x M y O z A mixed solution of metal salts corresponding to the metal elements of the catalyst carrier; S2: Under room temperature, the corresponding metal salt mixed solution and ammonia solution are co-precipitated to prepare the catalyst, the precipitation process is fully stirred, the pH value is adjusted to 8-11, aged at room temperature, filtered, washed, dried and then calcined to obtain the corresponding Ce x M y O z Carrier; S3: After dissolving palladium chloride in deionized water, add the carrier Ce x M y O z The catalyst was impregnated and allowed to stand for 8-12 h, and then dried and calcined to obtain a precursor, which was activated in a H2 atmosphere to obtain a supported palladium catalyst.

3. The method according to claim 1 or 2, characterized in that: Composite metal oxide supported palladium catalyst general formula Pd / Ce x M y O z The mass percentage of Pd is 0.05-0.5%, and the carrier Ce x M y O z Here, x:y ranges from 0.3 to 3, and z is the atomic ratio of oxygen required to satisfy the valence of each element.

4. The method according to claim 2, characterized in that: In the step S1, the corresponding metal salt is dissolved in deionized water to form a mixed solution with a concentration of 0.2-0.8 mol / L, and the metal salt is selected from one of sulfate, hydrochloride, nitrate and carbonate.

5. The method according to claim 2, characterized in that: In the step S2, the aging time is 10-15 h, the drying is carried out at 100-150° C., and the calcination is carried out at 300-600° C. for 4-8 h.

6. The method according to claim 2, characterized in that In the step S3, the precursor is dried at 60-100°C and calcined at 400-700°C for 3-7 h to obtain the precursor, and the precursor is activated in a H2 atmosphere at 100-400°C for 3-7 h.

7. The method according to claim 1, characterized in that The molar ratio of raw material acetone to isobutyraldehyde is 5.5-8.

5.

8. The method according to claim 1, characterized in that The liquid hourly space velocity of the raw material is 2.0-5.0 h -1 .

9. The method according to claim 1, characterized in that: The molar ratio of hydrogen to isobutyraldehyde is 2.13-10.

67.

10. The method according to claim 1, characterized in that The reaction temperature is 150-200 °C, and the reaction pressure is 1.0-3.0 MPa.