Process for synthesizing propionic acid through carbonylation and preparing 3-pentanone through decarboxylation

Abstract

The invention relates to the technical field of chemical raw material preparation, and particularly discloses a process for synthesizing propionic acid through carbonylation and preparing 3-pentanone through decarboxylation, and the process comprises the following steps: S1, preparing raw materials including ethylene, carbon monoxide, hydrogen and a composite catalyst; s2, filling the composite catalyst into a reactor, activating, and introducing ethylene, carbon monoxide and hydrogen into the reactor; s3, the reactor is heated in a microwave heating mode, ethylene, carbon monoxide and hydrogen are subjected to a carbonylation reaction, and propionic acid is generated. Compared with the prior art, the process for synthesizing propionic acid through carbonylation and preparing 3-pentanone through decarboxylation has the advantages that raw materials are low in cost and easy to obtain, a target product is produced in two steps, different catalysts do not need to be used in two reaction stages respectively, catalyst replacement steps are reduced, the whole preparation process is simpler and more efficient, and due to the simplification of the steps, the production cost is reduced. And the switching and operation time of the equipment is reduced, so that the production efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of chemical raw material preparation, and in particular to a process for synthesizing propionic acid through carbonylation and preparing 3-pentanone through decarboxylation. Background Art

[0002] As an important fine chemical raw material and high-end solvent, 3-pentanone is a key intermediate of the herbicide pendimethalin and the anti-avian influenza drug Tamiflu. Its usage is increasing year by year and it is widely used in synthetic dyes, medicine, agriculture and other fields. The main physical and chemical properties of 3-pentanone are: melting point -40°C, boiling point 101.5°C, density 0.815, refractive index n20 / D1.392, flash point 44.6°F, relative polarity 0.265, pH 6.2.

[0003] At present, the main preparation methods of 3-pentanone include alcohol oxidation method and ketone rearrangement method, which often have problems such as high raw material cost, harsh reaction conditions, low product purity, etc. In terms of catalysts, the existing preparation methods often need to use different catalysts for different reactions respectively, with many steps, which increases the complexity and cost of the operation. At the same time, the compatibility and synergistic effect between different catalysts are difficult to ensure, which may affect the effect of the reaction.

[0004] Therefore, it is necessary to propose a process for synthesizing propionic acid by carbonylation and preparing 3-pentanone by decarboxylation to solve the above problems. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the defects of the prior art. The present invention provides a process for synthesizing propionic acid by carbonylation and preparing 3-pentanone by decarboxylation, which solves the problems of high raw material cost, harsh reaction conditions, low product purity, etc. in the prior art.

[0006] To achieve the above object, the technical solution adopted by the present invention is: A process for synthesizing propionic acid by carbonylation and preparing 3-pentanone by decarboxylation, comprising the following steps: S1: Raw material preparation, ethylene, carbon monoxide, hydrogen, composite catalyst; S2: loading the composite catalyst into a reactor and performing activation treatment, and then introducing ethylene, carbon monoxide and hydrogen into the reactor; S3: heating the reactor by microwave heating, and ethylene, carbon monoxide and hydrogen undergo carbonylation reaction to produce propionic acid; S4: After the reaction is completed, the product is separated from the reaction system and purified to obtain pure propionic acid; S5: loading the composite catalyst into a reactor and performing an activation treatment, then adding the propionic acid obtained in step S4 into the reactor, heating the reactor by microwave heating, and causing the propionic acid to undergo a decarboxylation reaction to produce 3-pentanone; The composite catalyst contains at least two active centers, one part of which is used for carbonylation reaction and the other part is used for decarboxylation reaction.

[0007] Preferably, in step S2, the molar ratio of ethylene to carbon monoxide is between 1:1-1:2, and the molar ratio of hydrogen to carbon monoxide is between 1:1-2:1.

[0008] Preferably, the 3-pentanone and gaseous product generated by the reaction in step S5 are cooled and separated, and further purified to obtain high-purity 3-pentanone.

[0009] Preferably, the preparation method of the composite catalyst comprises the following steps: S11: preparing carrier material; S12: introducing hydroxyl or carboxyl functional groups on the surface of the support material by acid treatment, alkali treatment or oxidation treatment; S13: preparing at least two active centers, wherein one part of the active centers uses a transition metal, and the other part uses an alkali metal, an alkaline earth metal, or a transition metal oxide; S14: Loading two or more active centers on a carrier material.

[0010] Preferably, in step S5, the pressure in the reactor is maintained at normal pressure or slightly negative pressure, and during the decarboxylation reaction, the carboxyl group in the propionic acid molecule removes a carbon dioxide molecule to form a carbon anion intermediate, and the carbon anion intermediate reacts with another propionic acid molecule to form 3-pentanone.

[0011] Preferably, in step S13 of the preparation method of the composite catalyst, the transition metal is rhodium or cobalt, and when the transition metal is rhodium, the reaction temperature in step S3 is 150-180°C, and when the transition metal is cobalt, the reaction temperature in step S3 is 200-250°C.

[0012] Preferably, in step S13 of the method for preparing the composite catalyst, the alkali metal is sodium or potassium, the alkaline earth metal is calcium or magnesium, and the transition metal oxide is zinc oxide or copper oxide.

[0013] Preferably, in step S11 of the method for preparing the composite catalyst, the carrier material is porous alumina or silicon dioxide or a carbon material, wherein the carbon material is activated carbon or carbon nanotubes.

[0014] Preferably, in step S14 of the method for preparing the composite catalyst, two or more active centers are loaded on the carrier material by one or more methods selected from the group consisting of coprecipitation, impregnation, and ion exchange.

[0015] Preferably, in step S3 and step S5, an inert atmosphere is introduced into the reactor for protection during the reaction.

[0016] Compared with the prior art, the beneficial effects of the present invention include: 1. Compared with the existing method, the process of synthesizing propionic acid by carbonylation and preparing 3-pentanone by decarboxylation has low raw material cost and is easy to obtain, and the target product is produced in two steps. In addition, there is no need to use different catalysts in the two reaction stages, which reduces the catalyst replacement steps, making the entire preparation process more concise and efficient. Due to the simplification of steps, the switching and operation time of the equipment are reduced, thereby improving the production efficiency. At the same time, it also reduces the human errors that may be caused by complicated operation steps; 2. The process of carbonylation to synthesize propionic acid and decarboxylation to prepare 3-pentanone can quickly and evenly increase the reaction temperature and shorten the reaction time by setting microwave heating. Compared with traditional heating methods, such as oil bath heating or electric heating jacket heating, microwave heating can more effectively provide the energy required for the reaction and increase the reaction rate. 3. In the process of synthesizing propionic acid by carbonylation and preparing 3-pentanone by decarboxylation, the composite catalyst contains multiple active centers, which are respectively used for carbonylation reaction and decarboxylation reaction, thereby realizing the multifunctionality of the catalyst. This design can improve the utilization efficiency of the catalyst, reduce the amount of catalyst used, and reduce the cost. There can be synergistic effects between different active centers to improve the efficiency and selectivity of the reaction. For example, the carbonylation reaction active center can promote the efficient conversion of ethylene and synthesis gas into propionic acid, while the decarboxylation reaction active center can quickly convert propionic acid into 3-pentanone in the subsequent steps, thereby reducing the accumulation of intermediates and the occurrence of side reactions. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The disclosure of the present invention is described with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. In the accompanying drawings, the same reference numerals are used to refer to the same components. Among them: Figure 1 It is a schematic diagram of the process flow of the present invention; Figure 2 It is a schematic diagram of the process flow of preparing the composite catalyst of the present invention. DETAILED DESCRIPTION

[0018] It is easy to understand that according to the technical solution of the present invention, without changing the essential spirit of the present invention, a person skilled in the art can propose a variety of interchangeable structural modes and implementation modes. Therefore, the following specific implementation modes and drawings are only exemplary descriptions of the technical solution of the present invention, and should not be regarded as the whole of the present invention or as a limitation or restriction to the technical solution of the present invention.

[0019] According to one embodiment of the present invention, Figure 1-2 Shown.

[0020] like Figure 1 As shown, a process for synthesizing propionic acid by carbonylation and preparing 3-pentanone by decarboxylation comprises the following steps: Step 1: Raw material preparation, ethylene, synthesis gas, composite catalyst, wherein the synthesis gas is carbon monoxide and hydrogen; Step 2: loading the composite catalyst into a reactor and performing an activation treatment, and then introducing ethylene and synthesis gas into the reactor in a ratio, the specific ratio being: the optimal molar ratio of ethylene to carbon monoxide is generally between 1:1-1:2, excess carbon monoxide can increase the conversion rate of ethylene, but excessive carbon monoxide may cause an increase in side reactions, and the optimal molar ratio is preferably 1:1.5 as determined by experiments, and the amount of hydrogen is adjusted according to the properties of the catalyst and the reaction conditions, hydrogen can promote the reaction, and excess hydrogen may cause an increase in hydrogenation side reactions, and the molar ratio of hydrogen to carbon monoxide can be between 1:1-2:1 through experiments, preferably 1.5:1; Table 1 is an experimental comparative example of the molar ratio of ethylene to carbon monoxide: Table 1 Ethylene:CO molar ratio Ethylene conversion rate (%) Propionic acid selectivity (%) By-products (butyraldehyde + acetic acid, %) 1:1 82 88 8 1:1.5 92 90 5 1:2 95 85 10 It can be seen from Table 1 that, under the same other reaction conditions, ethylene: When the molar ratio is 1:1, Insufficient, low ethylene conversion rate, incomplete carbonylation reaction, ethylene: When the molar ratio is 1:1.5, Excessive promotion of ethylene conversion, while the increase of by-products is not significant, the overall performance is the best, ethylene: When the molar ratio is 1:2, Too much will lead to an increase in side reactions (such as deep carbonylation) and a decrease in propionic acid selectivity; Table 2 is an experimental comparative example of the molar ratio of hydrogen to carbon monoxide: Table 2 <![CDATA[H 2 :CO molar ratio]]> Ethylene conversion rate (%) Propionic acid selectivity (%) Hydrogenation by-products (ethanol, %) 1:1 88 87 5 1.5:1 92 90 3 2:1 90 85 8 It can be seen from Table 2 that, under the same other reaction conditions, : When the molar ratio is 1:1, Insufficient, limited hydrogenation step, slow reaction rate, : When the molar ratio is 1.5:1, Proper amount of carbonylation reaction is promoted, and hydrogenation by-products are less, with the best overall effect. : When the molar ratio is 2:1, Excessive addition leads to an increase in hydrogenation side reactions (producing ethanol) and a decrease in propionic acid selectivity; Step 3: The reactor is heated by microwave heating. Microwave heating can quickly and evenly increase the reaction temperature, shorten the reaction time, and improve the reaction efficiency. At the same time, microwaves can stimulate the activity of the catalyst and promote the reaction. The pressure is controlled between 1-10MPa, preferably 7MPa. The reaction is carried out under an inert atmosphere. Ethylene and synthesis gas undergo carbonylation reaction to produce propionic acid. The chemical formula is: The by-products of this stage are a small amount of butyraldehyde and acetic acid, which can be separated by distillation and sold as by-products; Table 3 is a comparative example of pressure experiments: Table 3 Pressure (MPa) Ethylene conversion rate (%) Reaction time (minutes) Equipment complexity and cost 5 85 60 Lower 7 92 45 medium 9 94 40 Higher It can be seen from Table 3 that, under the same other reaction conditions, when the pressure is low, the reaction rate is slow and the conversion rate is not optimal. Increasing the pressure increases the reaction rate and conversion rate, while the equipment cost is controllable and the overall cost performance is the highest. Although too high a pressure increases the reaction rate, the pressure resistance requirement of the equipment increases, the cost rises, and the by-products do not significantly decrease. 7MPa strikes a balance between the reaction rate, conversion rate and equipment cost, so it is selected as the preferred pressure. Step 4: After the reaction is completed, the product is separated from the reaction system and purified to obtain pure propionic acid. The specific method is to separate the propionic acid from the reaction mixture by distillation and extraction, and purify it by distillation and adsorption; Step 5: The composite catalyst is loaded into a reactor and activated, and then the propionic acid obtained in step S4 is added to the reactor. The reactor is preferably a tubular reactor made of high temperature resistant materials to withstand high temperature reaction conditions. The reactor is heated by microwave heating to raise the reactor temperature to between 350-450°C, preferably to 380°C. The pressure is normal pressure operation, and the propionic acid undergoes a decarboxylation reaction to produce 3-pentanone. The specific reaction principle is that under the action of high temperature and catalyst, the propionic acid molecule undergoes a decarboxylation reaction, and the carboxyl group ( ) removes a carbon dioxide molecule ( ), forming a carbon anion intermediate, which quickly reacts with another propionic acid molecule to form 3-pentanone. The specific reaction process is as follows: The carbon anion intermediate formed after the decarboxylation of the propionic acid molecule attacks the carbonyl carbon of another propionic acid molecule ( ), after a series of electron transfer and rearrangement, 3-pentanone molecules are formed, and the reaction formula is: The reaction is carried out in the reactor under normal pressure or slightly negative pressure. The slightly negative pressure can promote the timely discharge of carbon dioxide produced by the reaction to avoid adverse effects on the reaction balance. The reaction is carried out under an inert atmosphere to avoid side reactions such as oxidation. Nitrogen or argon is used as the protective atmosphere. The by-products of this stage are , which can be captured by membrane separation technology and used in carbonated beverage production or greenhouse gas emission reduction. The unreacted propionic acid can be recovered by distillation and recycled. Table 4 is an experimental comparative example of temperature during decarboxylation reaction: Table 4 Temperature (°C) Propionic acid conversion rate (%) 3-Pentanone selectivity (%) By-product (acetone, %) 350 88 82 10 380 95 88 5 400 96 85 8 450 97 80 12 As shown in Table 4, when other reaction conditions are the same, at 350°C, the temperature is low, the decarboxylation reaction rate is slow, the propionic acid conversion rate and the 3-pentanone selectivity are low, at 380°C, the temperature is increased, the decarboxylation reaction is accelerated, the 3-pentanone selectivity is the highest, and the amount of by-product acetone generated is small, at 400°C, the temperature is too high, resulting in deep decomposition of part of the propionic acid, a decrease in the 3-pentanone selectivity, and an increase in by-products, at 450°C, the high temperature intensifies the side reaction, and the 3-pentanone selectivity is significantly reduced, so at 380°C, the propionic acid conversion rate and the 3-pentanone selectivity reach a balance, and the by-products are the least, so it is selected as the preferred temperature; Step 6: The 3-pentanone and gaseous product generated in the reaction in the above step 5 flow out of the reactor, and the gaseous product is cooled by a cooling device to condense the 3-pentanone into a liquid. The condensed liquid is separated and purified to remove impurities and unreacted propionic acid, thereby obtaining high-purity 3-pentanone; The composite catalyst contains at least two composite catalysts with different active centers, one of which is used for carbonylation reaction and the other is used for decarboxylation reaction, which can simplify the process and reduce the types of catalysts used and the separation steps; like Figure 2 As shown, the specific preparation steps for the composite catalyst are: 1. Select the carrier: Use a carrier material with high specific surface area, good thermal stability and chemical stability, specifically porous alumina or silica or carbon material (activated carbon, carbon nanotubes), preferably porous alumina, which can provide a large number of attachment sites, which is conducive to the dispersion and stabilization of the active center.

[0021] 2. Modify the surface of the carrier and introduce specific functional groups or defects to enhance the interaction with the active center. Specifically, introduce hydroxyl or carboxyl functional groups on the surface of the carrier through acid treatment, alkali treatment or oxidation treatment. Preferably, nitric acid is used to treat porous alumina to introduce hydroxyl functional groups to increase the loading capacity and stability of the active center.

[0022] 3. Determine the combination of active centers: For the carbonylation reaction of ethylene and synthesis gas to generate propionic acid, a highly active transition metal is selected as the active center, specifically rhodium or cobalt. When a rhodium catalyst is selected, the reaction temperature in step 3 is 150-180°C, preferably 180°C. When a cobalt catalyst is selected, the reaction temperature in step 3 is 200-250°C, preferably 220°C. Rhodium or cobalt can form active species to promote the insertion of carbon monoxide into ethylene molecules and react with hydrogen; Table 5 is a temperature comparison of rhodium / cobalt catalysts in carbonylation reactions: Table 5 Catalyst type Temperature (°C) Ethylene conversion rate (%) Propionic acid selectivity (%) Rhodium Catalyst 150 78 85 Rhodium Catalyst 180 89 92 Cobalt Catalyst 200 85 88 Cobalt Catalyst 220 92 90 As shown in Table 5, when other reaction conditions are the same, at 150°C, the temperature is too low, the rhodium catalyst activity is insufficient, and the ethylene conversion rate is low. At 180°C, the rhodium catalyst activity is optimal, and the ethylene conversion rate and propionic acid selectivity are both high. The cobalt catalyst begins to show high activity at 200°C, but the selectivity is slightly lower than that of the rhodium catalyst. At 220°C, the activity of the cobalt catalyst reaches a peak, the ethylene conversion rate is the highest, and the propionic acid selectivity is equivalent to that of the rhodium catalyst. Therefore, the rhodium catalyst is preferably 180°C, and the cobalt catalyst is preferably 220°C, which correspond to their optimal activity temperatures, respectively, to ensure that the carbonylation reaction is carried out efficiently. For the decarboxylation reaction of propionic acid, an active center capable of promoting the removal of the carboxyl group is used, and an alkali metal (sodium or potassium) or an alkaline earth metal (calcium or magnesium) or a transition metal oxide (zinc oxide or copper oxide) is used, preferably zinc oxide (ZnO loading 5wt%) and potassium (K loading 2wt%). The active center can provide alkaline sites or redox activity to promote the decarboxylation reaction of propionic acid.

[0023] 4. Combine different active centers in one catalyst and load the two active centers on the carrier by coprecipitation, impregnation or ion exchange. Specifically, (0.05mol / L) and (0.1mol / L) was mixed, deionized water was added to make a 1L solution, 25% ammonia water was slowly added dropwise under stirring, the pH was adjusted to 9.0, the temperature was maintained at 60°C, stirring was continued for 2 hours, the precipitate was filtered, washed with deionized water until neutral, dried at 120°C for 12 hours, and then calcined at 500°C for 4 hours to obtain Composite carrier, impregnation method Dissolve in deionized water to make a 0.02 mol / L solution. Carrier immersion The solution was stirred at room temperature for 12 hours. The loading amount reached 2wt%, and after filtration, it was dried at 120°C for 6 hours and then calcined at 400°C for 3 hours to form Composite catalyst; About catalyst stability test: Continuous reaction experiment: In a fixed bed reactor, propionic acid was continuously introduced with a catalyst loading of 50 g (liquid space velocity 0.5 h - ¹), reaction temperature 380°C, the results showed that the catalyst activity remained stable within 100 hours, and the 3-pentanone selectivity was maintained above 85%.

[0024] Regeneration experiment: After the deactivated catalyst was calcined at 500°C in air atmosphere for 4 hours, its activity recovered to 90% of that of the fresh catalyst and could be reused 3 times.

[0025] Compared with the prior art, the scheme of converting ethylene and synthesis gas into propionic acid and then producing 3-pentanone has the following advantages: Wide sources of raw materials: Ethylene is an important basic chemical raw material with large output and easy access. Synthesis gas (carbon monoxide and hydrogen) can be produced through a variety of ways, such as coal gasification or natural gas reforming, which makes the raw material supply of this process relatively stable and not limited by a single resource. Compared with the expensive raw materials used in some traditional processes, the prices of ethylene and synthesis gas are relatively low, which helps to reduce production costs and improve the market competitiveness of products.

[0026] Simple and efficient steps: The process steps are relatively simple. Compared with some complex multi-step synthesis routes, the separation and purification steps of intermediate products are reduced, the production efficiency is improved, and there is no need to use different catalysts in the two reaction stages, which reduces the catalyst replacement steps, making the entire preparation process simpler and more efficient. Due to the simplification of steps, the switching and operation time of equipment are reduced, thereby improving production efficiency. At the same time, it also reduces the human errors that may be caused by cumbersome operation steps.

[0027] In terms of heating methods: microwave heating is fast and uniform. Microwave heating can quickly and evenly increase the reaction temperature and shorten the reaction time. Compared with traditional oil bath heating or electric heating jacket heating, microwave heating can more effectively provide the energy required for the reaction and increase the reaction rate. By adjusting the microwave power, the temperature in the reactor can be precisely controlled to avoid adverse effects of excessively high or low temperatures on the reaction, which helps to improve the selectivity and yield of the reaction.

[0028] Catalyst: The composite catalyst contains multiple active centers, which are used for carbonylation reaction and decarboxylation reaction respectively, realizing the multifunctionality of the catalyst, which can improve the utilization efficiency of the catalyst, reduce the amount of catalyst used, and reduce costs. In addition, there is a synergistic effect between different active centers, which improves the efficiency and selectivity of the reaction. The carbonylation reaction active center can promote the efficient conversion of ethylene and synthesis gas into propionic acid, while the decarboxylation reaction active center can quickly convert propionic acid into 3-pentanone in the subsequent steps, reducing the accumulation of intermediates and the occurrence of side reactions.

[0029] Fewer by-products: This process produces relatively few by-products, reducing pollution to the environment. At the same time, the recovery and utilization of by-products can also reduce production costs and achieve the recycling of resources.

[0030] The technical scope of the present invention is not limited to the contents in the above description. Those skilled in the art can make various deformations and modifications to the above embodiments without departing from the technical idea of ​​the present invention, and these deformations and modifications should all fall within the protection scope of the present invention.

Claims

1. A process for synthesizing propionic acid by carbonylation and preparing 3-pentanone by decarboxylation, characterized in that: The following steps are involved: S1: Raw material preparation, ethylene, carbon monoxide, hydrogen, composite catalyst; S2: loading the composite catalyst into a reactor and performing activation treatment, and then introducing ethylene, carbon monoxide and hydrogen into the reactor; S3: heating the reactor by microwave heating, and ethylene, carbon monoxide and hydrogen undergo carbonylation reaction to produce propionic acid; S4: After the reaction is completed, the product is separated from the reaction system and purified to obtain pure propionic acid; S5: loading the composite catalyst into a reactor and performing an activation treatment, then adding the propionic acid obtained in step S4 into the reactor, heating the reactor by microwave heating, and causing the propionic acid to undergo a decarboxylation reaction to produce 3-pentanone; The composite catalyst contains at least two active centers, one part of which is used for carbonylation reaction and the other part is used for decarboxylation reaction.

2. The process for preparing 3-pentanone by carbonylation to propionic acid and decarboxylation according to claim 1, characterized in that: In step S2, the molar ratio of ethylene to carbon monoxide is between 1:1-1:2, and the molar ratio of hydrogen to carbon monoxide is between 1:1-2:

1.

3. The process for preparing 3-pentanone by carbonylation to propionic acid and decarboxylation according to claim 1, characterized in that: The 3-pentanone and gaseous product generated by the reaction in step S5 are cooled and separated, and further purified to obtain high-purity 3-pentanone.

4. The process for preparing 3-pentanone by carbonylation to propionic acid and decarboxylation according to claim 1, characterized in that: The preparation method of the composite catalyst comprises the following steps: S11: preparing carrier material; S12: introducing hydroxyl or carboxyl functional groups on the surface of the support material by acid treatment, alkali treatment or oxidation treatment; S13: preparing at least two active centers, wherein one part of the active centers uses a transition metal, and the other part uses an alkali metal, an alkaline earth metal, or a transition metal oxide; S14: Loading two or more active centers on a carrier material.

5. The process for preparing 3-pentanone by carbonylation to propionic acid and decarboxylation according to claim 1, characterized in that: In step S5, the pressure in the reactor is maintained at normal pressure or slightly negative pressure, and during the decarboxylation reaction, the carboxyl group in the propionic acid molecule removes a carbon dioxide molecule to form a carbon anion intermediate, and the carbon anion intermediate reacts with another propionic acid molecule to form 3-pentanone.

6. The process for preparing 3-pentanone by carbonylation to propionic acid and decarboxylation according to claim 4, characterized in that: In step S13 of the preparation method of the composite catalyst, the transition metal is rhodium or cobalt, and when the transition metal is rhodium, the reaction temperature in step S3 is 150-180°C, and when the transition metal is cobalt, the reaction temperature in step S3 is 200-250°C.

7. The process for preparing 3-pentanone by carbonylation to propionic acid and decarboxylation according to claim 4, characterized in that: In step S13 of the method for preparing the composite catalyst, the alkali metal is sodium or potassium, the alkaline earth metal is calcium or magnesium, and the transition metal oxide is zinc oxide or copper oxide.

8. The process for preparing 3-pentanone by carbonylation to propionic acid and decarboxylation according to claim 4, characterized in that: In step S11 of the method for preparing the composite catalyst, the carrier material is porous alumina or silicon dioxide or a carbon material, wherein the carbon material is activated carbon or carbon nanotubes.

9. The process for preparing 3-pentanone by carbonylation to propionic acid and decarboxylation according to claim 4, characterized in that: In step S14 of the method for preparing the composite catalyst, two or more active centers are loaded on the support material by one or more methods selected from the group consisting of coprecipitation, impregnation, and ion exchange.

10. The process for preparing 3-pentanone by carbonylation to propionic acid and decarboxylation according to claim 1, characterized in that: In step S3 and step S5, an inert atmosphere is introduced into the reactor for protection during the reaction.

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