Preparation and use of a composite oxide catalyst for the selective oxidation of propionaldehyde to acrylic acid

Abstract

The patent discloses a preparation method of Mo-V-Sb-Na-O composite oxide catalyst and application of the Mo-V-Sb-Na-O composite oxide catalyst in a reaction of preparing acrylic acid from propylene aldehyde, and comprises the following steps: using a solvent evaporation method to prepare a Mo-V series catalyst, dissolving ammonium heptamolybdate, ammonium metavanadate and antimony trioxide in deionized water and uniformly mixing under rapid stirring, and drying and calcining the mixed liquid to obtain a high-activity catalyst for selectively oxidizing propylene aldehyde into acrylic acid, i.e. a composite oxide catalyst. The composite oxide catalyst prepared by the above method has the advantages of simple operation process, short preparation time, good selectivity and yield of acrylic acid.

Description

Technical Field

[0001] This invention relates to the field of catalytic oxidation technology, specifically to a composite oxide catalyst containing molybdenum-vanadium-antimony-oxygen (MoVSbNaO). This catalyst, through precise control of the atomic ratio and phase structure of Mo, V, Sb, and Na, solves the problems of low activity, poor selectivity for acrylic acid, and insufficient stability in the oxidation of acrolein by traditional catalysts. In a gas-phase reaction system, it can efficiently activate acrolein molecules and oxygen, inhibiting excessive oxidation to generate byproducts such as CO2 and CO, and exhibits good thermal stability and long-term performance. In terms of application scenarios, it can be adapted to mainstream industrial reactors such as fixed-bed and fluidized-bed reactors, providing a highly efficient catalytic solution for the industrial production of acrolein into high-value-added acrylic acid, combining technological innovation with practical application value. Background Technology

[0002] Acrylic acid, a typical unsaturated carboxylic acid, is an indispensable core raw material in the field of organic chemical engineering. Its chemically reactive properties allow for the derivation of diverse products through polymerization, esterification, and other reactions. Core applications include the production of acrylates, acrylic resins, acrylic elastomers, and polyacrylates. These derivatives, with their excellent weather resistance, adhesion, and elasticity, have deeply penetrated key sectors of the national economy and everyday life, including coatings, adhesives, textile auxiliaries, sanitary materials, automobile manufacturing, and building waterproofing, resulting in a continuously and steadily increasing market demand. Given its wide range of applications and enormous market potential, efficient, low-cost, and green production technologies for acrylic acid have long been a research hotspot and key focus in the chemical industry.

[0003] Mo-V-Sb mixed oxides are excellent catalytic systems for the selective oxidation of propylene or propane to acrylic acid. Francisco Ivars et al. prepared niobium-free Mo-V-Sb catalysts, obtaining a pure M1 phase via hydrothermal treatment, hydrogen peroxide post-treatment, and water washing. They confirmed that the M1 phase is key to the catalysis, while the M2 phase is relatively unfavorable to the reaction. P. Botella et al. studied similar niobium-free catalysts and found that the preparation and calcination temperatures affect performance, with the M1 phase playing a core role. After the reaction, some of the trivalent Sb on the surface is oxidized, and the catalyst requires activation at 400℃ to reach a stable state. T. Blasco et al. prepared K-doped Mo-V-Sb catalysts via a hydrothermal combined with impregnation method. K did not change the bulk structure of the catalyst but reduced surface acid sites and promoted Sb3+ surface oxidation, thereby improving the selectivity for acrylic acid. Most reported Mo-V-Sb mixed oxide catalysts have high costs due to complex preparation processes, limiting their industrial application. Therefore, there is an urgent need to develop simpler and more efficient synthesis methods to prepare highly active catalysts and promote their practical application. Summary of the Invention

[0004] This invention aims to overcome the shortcomings of existing catalysts for the oxidation of acrolein to acrylic acid, such as low activity, poor selectivity, and insufficient stability, as well as the complex preparation, high cost, and difficulty in adapting traditional Mo-V-Sb-Na mixed oxide catalysts to the acrolein oxidation reaction. It provides a Mo-V-Sb-Na composite oxide catalyst with controllable composition and simple preparation, enabling its efficient application in the gas-phase catalytic oxidation of acrolein. The Mo-V-Sb-Na mixed oxide catalyst prepared by this method has a high specific surface area, thereby improving the reactivity of the selective oxidation of acrolein to acrylic acid.

[0005] This invention provides a method for preparing a catalyst for the selective oxidation of acrolein to acrylic acid, comprising the following steps:

[0006] 1) Using ammonium heptamolybdate as the molybdenum source and antimony trioxide as the antimony source, the preparation steps of solution A are as follows: First, weigh an appropriate amount of ammonium heptamolybdate and dissolve it in deionized water, stirring until completely dissolved; then add antimony trioxide according to the preset molar ratio, heat and continuously stir to mix evenly.

[0007] 2) Using ammonium metavanadate as the vanadium source and sodium carbonate as the sodium source, prepare solution B by following these steps: Weigh a certain amount of ammonium metavanadate and sodium carbonate and dissolve them in oxalic acid solution; place the solution in a constant temperature water bath and heat and stir to form solution B.

[0008] 3) Transfer solution B to a beaker and place it on a magnetic stirrer to start stirring; then slowly add solution A to solution B, and continue magnetic stirring while maintaining a certain temperature to ensure that the entire system is fully mixed.

[0009] 4) First, the precursor solution is dried to remove water from the system, resulting in a solid precursor. Then, the obtained solid precursor is calcined. The solid product obtained after calcination is then pressed and granulated to finally obtain the Mo-V-Sb-Na composite oxide catalyst.

[0010] 5) The reaction of acrolein oxidation to acrylic acid in this invention is carried out in a fixed-bed reactor. A certain amount of the above-mentioned mixed oxide catalyst is loaded in the reaction tube. The reaction tube is placed in a heating jacket, and after leak detection by inert gas, the temperature is raised to 260~320℃ and kept at that temperature. The acrolein aqueous solution is pumped into the preheater by a constant flow pump, vaporized and mixed with air and nitrogen, and then enters the reaction tube for reaction. The product is condensed and collected by a condenser, and the tail gas is treated and discharged. The product is acrylic acid.

[0011] This invention provides a method for preparing a Mo-V-Sb-Na-O catalyst for the oxidation of acrolein to acrylic acid. The specific steps are as follows: First, a certain amount of ammonium heptamolybdate is weighed and dissolved in deionized water. Antimony trioxide is added according to a preset molar ratio of Mo to Sb, and the mixture is stirred until completely dissolved to form solution A. Solution A is then placed in a heating device and stirred until homogeneous. Sodium carbonate and ammonium metavanadate are weighed according to specific molar ratios of Na to Mo and V to Mo, respectively. They are dissolved in an acid solution and stirred until dissolved to obtain solution B. Solution B is then added to solution A under magnetic stirring and stirred continuously for a period of time to ensure thorough mixing, resulting in a mixed solution C. Mixed solution C is then dried in an oven at 80-100℃ to obtain a solid precursor. Finally, the solid precursor is calcined in a muffle furnace. The calcined product is then pressed into tablets, granulated, and screened using a standard sieve to obtain the target catalyst. Attached Figure Description

[0013] Figure 1 These are SEM images of Embodiments 1, 2, 3 and 4 of the present invention. Detailed Implementation

[0015] This invention provides a method for preparing a highly active catalyst for the selective oxidation of acrolein to acrylic acid, comprising the following steps:

[0016] Example 1.

[0017] 1) Weigh ammonium heptamolybdate, add it to deionized water, and stir on a magnetic stirrer until completely dissolved. Weigh 0.1~0.5g of antimony trioxide according to the Mo:Sb atomic ratio, and slowly add it to the above solution. Heat the mixture to 80℃ and stir continuously until the antimony trioxide is completely dissolved, forming solution A. Place solution A on a magnetic stirrer and maintain a gentle boil to evaporate until the solution volume is concentrated to a certain level. Stop heating and allow it to cool naturally to room temperature.

[0018] 2) Weigh a certain amount of oxalic acid and dissolve it in water to prepare an oxalic acid solution of a certain concentration. Then weigh 1-3g of ammonium metavanadate and 0.5-1.5g of sodium carbonate. Transfer the prepared oxalic acid solution to a constant temperature water bath. After the water bath temperature stabilizes, slowly add the ammonium metavanadate to the oxalic acid solution. Maintain magnetic stirring throughout the process to ensure that the ammonium metavanadate is fully dissolved, and finally obtain a black solution B.

[0019] 3) Transfer the precursor solution to a beaker and place it on an 80°C constant-temperature magnetic stirrer. Turn on the magnetic stirrer. Slowly add solution A prepared in step 16 to solution B. After all the solution has been added, continue stirring for 1 hour to ensure that the system is mixed evenly, resulting in a homogeneous mixed solution C.

[0020] 4) Transfer solution C to an oven and dry it to obtain a black block precursor. Grind it with a mortar and pestle and collect it for later use.

[0021] 5) The ground solid precursor was transferred to a muffle furnace and calcined in air. A dark gray solid powder was obtained. The powder was ground, compressed into tablets, and granulated using a tablet press. Particles of 20-40 mesh were screened using a standard sieve to obtain the Mo-V-Sb-Na composite oxide catalyst, denoted as Catalyst 1.

[0022] Example 2

[0023] 1) Weigh out ammonium heptamolybdate and dissolve it in deionized water. Weigh out 0.5~1g of antimony trioxide according to the Mo:Sb atomic ratio, and slowly add it to the solution. Heat the mixture and stir continuously to ensure that the antimony trioxide is completely dissolved to form a homogeneous solution A. Heat solution A to boiling and maintain a gentle boil to evaporate until the solution volume is concentrated to a certain level.

[0024] 2) Add oxalic acid to deionized water and stir until completely dissolved to prepare an oxalic acid solution of a certain concentration. Weigh 1-3g of ammonium metavanadate and 0.5-1.5g of sodium carbonate. Transfer the oxalic acid solution to a constant temperature water bath. After the temperature stabilizes, add the ammonium metavanadate and sodium carbonate to the oxalic acid solution until completely dissolved. Stir magnetically for a period of time to obtain solution B.

[0025] 3) Place solution B in an 80℃ magnetic stirrer and turn on the magnetic stirrer. Slowly add solution A from step 22 to solution B. After all the solution has been added, continue stirring for 1 hour to ensure the system is mixed evenly, resulting in a homogeneous solution C.

[0026] 4) The precursor solution C was dried in an oven until it became a black, blocky precursor. The precursor was then transferred to a muffle furnace and calcined in an air atmosphere. After cooling, it was ground, pressed into tablets, granulated, and screened to obtain catalyst 2.

[0027] Example 3

[0028] 1) Weigh out ammonium heptamolybdate and dissolve it in deionized water. Weigh out 1~1.5g of antimony trioxide according to a certain Mo:Sb atomic ratio, add it to the solution, and continue heating and stirring until the antimony trioxide is completely dissolved to form solution A. Transfer solution A to a magnetic stirrer and boil it to concentrate it to a certain volume.

[0029] 2) Weigh a certain amount of oxalic acid and dissolve it in deionized water to prepare an oxalic acid solution with a concentration of 0.056-0.111 mol / L. Weigh 1-3 g of ammonium metavanadate and 0.5-1.5 g of sodium carbonate. Place the oxalic acid solution in a constant-temperature magnetic stirring environment. After the temperature stabilizes, add the ammonium metavanadate to the oxalic acid solution and stir magnetically until both the ammonium metavanadate and sodium carbonate are completely dissolved to obtain solution B.

[0030] 3) Place solution B in a warm water bath and stir. Slowly add solution A to solution B and continue stirring for 1 hour to obtain a homogeneous solution C.

[0031] 4) The precursor solution was dried in a constant temperature oven to obtain the precursor, which was then ground, compressed into tablets, and screened into 20-40 mesh particles. The tablets were then calcined in a muffle furnace under an air atmosphere to obtain catalyst 3.

[0032] Example 4

[0033] 1) Weigh ammonium heptamolybdate and add it to deionized water. Stir on a magnetic stirrer until completely dissolved. Weigh a certain amount of Sb₂O₃ and slowly add it to the above solution. Transfer the mixture to a constant temperature water bath, set the temperature to 80℃, and simultaneously turn on the magnetic stirrer. Continue stirring to ensure that all Sb₂O₃ is dissolved, ultimately forming a homogeneous solution A. Heat solution A to boiling point and maintain a gentle boil to evaporate the solution, concentrating it to a certain volume.

[0034] 2) Pour 100 mL of deionized water into a beaker, add oxalic acid, and stir with a glass rod until completely dissolved to prepare an oxalic acid solution of a certain concentration. Weigh 2-5 g of ammonium metavanadate and 0.5-1.5 g of sodium carbonate. Gradually add the ammonium metavanadate and sodium carbonate to the oxalic acid solution in 5 portions, stirring continuously during the addition process to ensure complete dissolution before adding the next portion. Finally, obtain a homogeneous solution B without impurities, and let it stand for later use.

[0035] 3) Place solution B in an 80℃ constant-temperature magnetic stirrer, turn on the magnetic stirrer, and maintain a stable temperature. Slowly add solution A to solution B. After all the solution has been added, continue stirring at 80℃ for 1 hour to ensure that all components are fully mixed, ultimately obtaining a homogeneous solution C without stratification or precipitation.

[0036] 4) Transfer the precursor solution to an oven for drying to obtain a hard, black, blocky precursor. After removing it, grind it with an agate mortar and pestle, pass it through a 20-40 mesh sieve, and collect the precursor powder for later use.

[0037] 5) The precursor powder was placed in a muffle furnace and calcined in air as the calcination atmosphere. A dark gray, non-lumpy solid powder was obtained. The powder was ground, and a certain amount of powder was placed in a tablet press for tableting and granulation. Particles of 20-40 mesh were screened through a standard sieve to obtain the Mo-V-Sb-Na composite oxide catalyst, labeled as catalyst 4.

[0038] In this invention, the highly active catalyst for selective oxidation of acrolein to prepare acrylic acid is mixed with quartz sand and then catalytically reacted in a mixture of acrolein, oxygen, nitrogen, and water vapor to obtain acrylic acid.

[0039] In this invention, a highly active catalyst for the selective oxidation of acrolein to prepare acrylic acid is mixed with quartz sand, placed in a fixed-bed reactor, and the catalyst activity is tested at 200-320°C.

[0040] To more fully illustrate the technical content of the present invention, the following will describe in detail, with reference to specific embodiments, a method for preparing a highly active catalyst for the selective oxidation of acrolein to acrylic acid and its application. It should be noted that these embodiments are only used to exemplify the present invention and are not intended to limit the scope of protection of the present invention.

[0041] In this invention, the reaction for preparing acrylic acid from acrolein is carried out in a fixed-bed reactor with a reaction tube inner diameter of 14 mm and a length of 610 mm. A measured amount of catalyst is first weighed and filled into the reaction tube. Quartz wool is laid at both ends of the fixed-bed reaction tube, and quartz sand is then filled on the outside of the quartz wool to further improve the uniformity of gas-catalyst contact and ensure the reaction proceeds fully. The filled reaction tube is placed in a heating jacket. Gas is first introduced to check the sealing performance of each connection. After confirming no leaks, the reaction temperature is raised to 200-320℃ through the heating jacket and maintained within this temperature range for stable reaction. Oxygen is provided by an air cylinder, and nitrogen gas is simultaneously introduced at a certain flow rate as a carrier gas. An aqueous solution of acrolein is pumped into the reactor at a rate of 0.35 mL / min using a constant flow pump. After being preheated and vaporized into a gaseous state by a preheater, it enters the reaction tube and undergoes an oxidation reaction with oxygen to produce acrylic acid. The reaction products are first cooled by a condenser. The condensable components are collected in a dedicated device, while the non-condensable gases are treated to meet harmless standards before being discharged. Samples were taken periodically during the experiment, and qualitative and quantitative analysis of the products was performed using GC / MS coupled with GC. After the reaction reached steady state, the gaseous products were separated and detected using a PerkinElmer Clarus 500 gas chromatograph equipped with a HAYESEP DB100-120 packed column, and the liquid products were quantitatively detected using an SP-2000B chromatograph from Shandong Lu Chemical Instrument Co., Ltd., which is equipped with an FFAP capillary column and an FID detector to ensure detection accuracy.

[0042] The catalytic performance of the composite oxide catalyst prepared in Example 1 was tested:

[0043] The reaction for the oxidation of acrolein to prepare acrylic acid in this invention is carried out in a fixed-bed reactor, and the operation is as follows:

[0044] 1) A certain amount of catalyst 1 is packed into the reaction tube. Quartz wool is laid at both ends of the reaction tube, and quartz sand is filled outside the quartz wool. The packed reaction tube is placed in a heating jacket, and after connecting the pipeline, air is vented to check the seal. The temperature is then raised to 200-320℃ through the heating jacket and maintained within this range. Oxygen is provided by an air cylinder, and nitrogen is simultaneously vented at a certain flow rate. A 10% acrolein aqueous solution is prepared and pumped into the reactor at a constant flow rate of 0.35 mL / min. The aqueous solution is vaporized by a preheater and then enters the reaction tube to react with oxygen. The reaction products are cooled by a condenser. The condensable components are collected in a collection device, and the non-condensable gases are treated to render them harmless before being discharged.

[0045] 2) During the reaction, samples were taken periodically for qualitative and quantitative analysis using GC / MS and GC. After steady-state reaction, the gas phase products were detected by a PerkinElmer Clarus 500 gas chromatograph equipped with a HAYESEP DB100-120 column, and the liquid phase products were detected by a Shandong Lu Chemical Instrument SP-2000B chromatograph with an FFAP column and an FID detector.

[0046] The catalytic performance of the composite oxide catalyst prepared in Example 2 was tested:

[0047] 1) A certain amount of catalyst 2 is packed into the reaction tube. Quartz wool is laid at both ends of the reaction tube, and quartz sand is filled around the quartz wool. The packed reaction tube is placed in a heating jacket, and after connecting the pipeline, air is vented to check the seal. The temperature is then raised to 200-320℃ through the heating jacket and maintained within this range. Oxygen is supplied from an air cylinder, and nitrogen is introduced as a protective gas. A 10% acrolein aqueous solution is prepared and pumped into the reactor at a constant flow rate of 0.35 mL / min. The acrolein aqueous solution is vaporized by a preheater and then enters the reaction tube to undergo an oxidation reaction with oxygen. The reaction products are cooled by a condenser. The condensable components enter a collection device, and the non-condensable gases are treated to render them harmless before being discharged.

[0048] 2) During the reaction, samples were taken periodically for qualitative and quantitative analysis using GC / MS and GC. After steady-state reaction, the gas phase products were detected by a PerkinElmer Clarus 500 gas chromatograph equipped with a HAYESEP DB100-120 column, and the liquid phase products were detected by a Shandong Lu Chemical Instrument SP-2000B chromatograph with an FFAP column and an FID detector.

[0049] The catalytic performance of the composite oxide catalyst prepared in Example 3 was tested:

[0050] 1) A certain amount of catalyst 3 is packed into the reaction tube. Quartz wool is laid at both ends of the reaction tube, and quartz sand is filled around the quartz wool. The packed reaction tube is placed in a heating jacket, and after connecting the pipeline, air is vented to check the seal. The temperature is then raised to 260-320℃ through the heating jacket and maintained within this range. Oxygen is supplied from an air cylinder, and nitrogen is introduced. A 10% acrolein aqueous solution is prepared and pumped into the reactor at a constant flow rate of 0.35 mL / min. The acrolein aqueous solution is vaporized by a preheater and then enters the reaction tube to react with oxygen. The reaction products are cooled by a condenser. The condensable components are collected in a collection device, and the non-condensable gases are treated to render them harmless before being discharged.

[0051] 2) During the reaction, samples were taken periodically for qualitative and quantitative analysis using GC / MS and GC. After the reaction reached stability, the gas phase products were detected using a PerkinElmer Clarus 500 gas chromatograph equipped with a HAYESEP DB100-120 column, and the liquid phase products were detected using a Shandong Lu Chemical Instrument SP-2000B chromatograph with an FFAP column and an FID detector.

[0052] The catalytic performance of the composite oxide catalyst prepared in Example 4 was tested:

[0053] 1) A certain amount of catalyst 4 is packed into the reaction tube. Quartz wool is laid at both ends of the reaction tube, and quartz sand is filled outside the quartz wool. The packed reaction tube is placed in a heating jacket, and after connecting the pipeline, air is vented to check the seal. The temperature is then raised to 260-320℃ through the heating jacket and maintained within this range. Oxygen is supplied from an air cylinder, and nitrogen is introduced. A 10% acrolein aqueous solution is prepared and pumped into the reactor at a constant flow rate of 0.35 mL / min. The acrolein aqueous solution is vaporized by a preheater and then enters the reaction tube to react with oxygen. The reaction products are cooled by a condenser. The condensable components are introduced into a collection device, and the non-condensable gases are treated to render them harmless before being discharged.

[0054] 2) During the reaction, samples were taken periodically for qualitative and quantitative analysis using GC / MS and GC. After steady-state reaction, the gas phase products were detected by a PerkinElmer Clarus 500 gas chromatograph equipped with a HAYESEPDB100-120 column, and the liquid phase products were detected by a Shandong Lu Chemical Instrument SP-2000B chromatograph with an FFAP column and an FID detector.

[0055] The catalyst in the examples exhibits high conversion capacity in the selective oxidation of acrolein to acrylic acid, with an acrolein conversion rate of approximately 99% and an acrylic acid selectivity ranging from 80.75% to 89.33%. Under suitable conditions, the catalyst of this invention can achieve a total acrylic acid selectivity of 89.33%, demonstrating high economic value.

[0058] The embodiments and descriptions above are merely illustrative of the principles and preferred embodiments of the present invention. Various changes and modifications may be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A method for preparing a Mo-V-Sb-Na-O catalyst for the oxidation of acrolein to acrylic acid, comprising the following steps: A measured amount of ammonium heptamolybdate is dissolved in deionized water. Sb₂O₃ of the corresponding mass is added according to a preset Mo to Sb molar ratio, and the mixture is stirred continuously until completely dissolved, forming a blue-brown solution A. Solution A is placed in a heating device and evaporated and concentrated under boiling conditions. Ammonium metavanadate and sodium carbonate of the corresponding mass are weighed according to preset Na to Mo and V to Mo molar ratios, respectively, and dissolved in an acid solution. The mixture is stirred until completely dissolved, forming solution B. Under magnetic stirring, solution B is gradually added dropwise to solution A. After the addition is complete, magnetic stirring is continued for a period of time to obtain a homogeneous mixed solution C. The precursor solution is statically dried overnight in a 100°C oven to remove moisture, yielding a solid precursor. The solid precursor is placed in a muffle furnace and calcined at a constant temperature under certain conditions. The calcined product is then tableted by a tablet press, mechanically crushed and granulated, and screened through a standard sieve to select 20-40 mesh particles, thus obtaining the target Mo-V-Sb-Na-O catalyst.

2. The preparation method according to claim 1, characterized in that, The Mo-V-Sb-Na-O composite oxide catalyst is prepared using a solvent evaporation method.

3. The preparation method according to claim 1, characterized in that, Solution A requires the addition of ammonium heptamolybdate, which is dissolved in 200 mL of aqueous solution; 0.5~1 g of Sb2O3 is added according to a preset molar ratio, and the mixture is stirred to dissolve and form a blue-brown solution A. Solution A is then evaporated and concentrated under boiling conditions.

4. The preparation method according to claim 1, characterized in that, The acid solution is an oxalic acid solution, with 0.5-1g of ammonium metavanadate and 0.5-1.5g of sodium carbonate added. The mixture is stirred and dissolved to form a black solution B.

5. The preparation method according to claim 1, characterized in that, The calcination temperature of the solid precursor is 400~600℃.

6. The preparation method according to claim 1, characterized in that, In the prepared Mo-V-Sb-Na-O catalyst, Mo and V are the basic active components, and Sb and Na are the promoters.

7. The application according to claim 1, characterized in that, The reaction of acrolein oxidation to prepare acrylic acid was carried out in a fixed-bed reactor: a certain mass of catalyst was loaded, the reaction temperature was controlled at 200~320℃, and the reaction was completed in a homogeneous catalytic system composed of acrolein, oxygen, nitrogen and water vapor to produce acrylic acid.

Images