Catalyst for preparing methacrylic acid by one-step oxidation of isobutylene and method for preparing methacrylic acid

Abstract

The present invention discloses a catalyst for preparing methacrylic acid by a one-step oxidation process of isobutylene and a method for preparing methacrylic acid, belonging to the technical field of chemical synthesis. The catalyst of the present invention comprises a composite metal oxide component and a heteropoly acid component; the composite metal oxide component is composed of Mo7V3P 0.3 Ce a O 27 , wherein a represents the number of atoms of Ce element, and the value is 0.05-0.1; the composition of the heteropoly acid component is K 0.6 CsWH 1.4 PMo 11 VO 40 The catalyst of the present invention has two active components and can directly oxidize isobutylene to methacrylic acid in one step. Compared with the single-component catalyst in the prior art, the two-component composite structure has good thermal stability, high conversion rate and good methacrylic acid selectivity.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical synthesis, and particularly relates to a catalyst for preparing methacrylic acid through a one-step oxidation process of isobutylene and a method for preparing methacrylic acid. Background Art

[0002] Methacrylic acid is an important organic synthetic raw material and chemical intermediate, widely used in chemical products such as synthetic resins, polymers, coatings and adhesives.

[0003] Currently, the production method of methacrylic acid by oxidation of isobutylene generally involves two steps: first, oxidation of isobutylene to methacrolein, typically using a Mo-Bi or Mo-V composite metal oxide catalyst; then, oxidation of methacrolein to methacrylic acid, typically using an oxidant such as a Mo-P-based heteropolyacid. For the first step, patent document CN113710362 B describes a catalytic reaction in a tubular fixed-bed reactor using Mo, Bi, and Fe as the primary active components and Co, Ni, Cs, and W as co-catalysts to produce methacrolein. The reaction achieves an isobutylene conversion of up to 95.4%, with a methacrolein selectivity of 85.7%, while the selectivity for methacrylic acid is lower at only 4.2%. Patent document CN114917924 B describes a supported catalyst whose primary active component is Au and whose support is a composite metal oxide containing Mo, Bi, and Co. By introducing a small amount of gold during the preparation process, this catalyst reduces the oxidation reaction temperature, thereby improving the selectivity of the selective oxidation of isobutylene to methacrolein. For the second step reaction, patent document CN 116196955 A uses a heteropolyacid catalyst composed of Mo, V, P, and Ag as the primary active components. A thermal conductor is added to shape the catalyst. During catalyst preparation, microwave reaction and step-by-step calcination are employed to achieve high methacrolein conversion and methacrylic acid selectivity under relatively mild reaction conditions. Patent document CN 114849747 B adds K, Cs, and NH4 to the Mo-P heteropolyacid as countercations, and uses kaolin as a catalyst support to enhance catalyst acidity, methacrylic acid selectivity, and thermal stability. A review of several patent documents reveals that most methods for preparing methacrylic acid employ a two-step process, with the reaction carried out in two different catalyst systems and two reactor stages.

[0004] Currently, there are a few reports on catalyst systems for preparing methacrylic acid using a one-step oxidation process. Patent document CN 114849740A uses a composite oxide catalyst with Mo and V as the main active components, and Te and Cs as co-catalysts, to improve the selectivity of isobutylene to methacrylic acid. The isobutylene conversion rate is 90%, and the selectivity for methacrylic acid is as high as 70%. However, the preparation process of this catalyst is not environmentally friendly, and expensive and explosive reagents are used. Patent document CN 114471530 A disperses a Mo-Bi composite oxide in a surfactant and combines it with a Mo-P-based heteropoly compound containing a silica precursor to form a two-component catalyst. This improves the thermal stability of the heteropolyacid catalyst, achieving an isobutylene conversion rate of 97.0% and a methacrylic acid selectivity of 78.4%. However, bismuth nitrate, the precursor of the main component Bi, is insoluble in water, so nitric acid solution is used as the solvent during the preparation process, which is environmentally harmful and requires high equipment. Currently, research on catalysts for the one-step oxidation of isobutylene to methacrylic acid has shown that, while isobutylene conversion is high, selectivity for the target product, methacrylic acid, is low. Therefore, there is an urgent need to develop a one-step oxidation method for producing methacrylic acid using isobutylene as a raw material that is pollution-free, has high atom utilization, and exhibits high selectivity for methacrylic acid. This would significantly reduce the complexity of the reaction process, minimize initial equipment investment, and lower production costs. Summary of the Invention

[0005] In view of the problems existing in the prior art, the object of the present invention is to provide a catalyst for preparing methacrylic acid by a one-step oxidation process of isobutylene and a method for preparing methacrylic acid.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A catalyst for preparing methacrylic acid by a one-step oxidation process of isobutylene, comprising a composite metal oxide component and a heteropoly acid component; the composite metal oxide component is composed of Mo7V3P 0.3 Ce a O 27 , wherein a represents the number of atoms of Ce element, and the value is 0.05-0.1; the composition of the heteropoly acid component is K 0.6 CsWH 1.4 PMo 11 VO 40 .

[0008] Based on the above solution, the mass ratio of the composite metal oxide component to the heteropolyacid component is 3:2-1:4.

[0009] The preparation method of the catalyst for preparing methacrylic acid by the one-step oxidation of isobutylene comprises the following steps:

[0010] An aqueous solution of a composite metal oxide component is added to a solution of a heteropolyacid component, the mixture is stirred, the solvent is evaporated, and the mixture is dried to obtain a yellow solid. The solid is ground into powder, and the powder is calcined at 300-450°C for 5-12 hours at a heating rate of 5°C / min to obtain a catalyst for preparing methacrylic acid by a one-step oxidation process of isobutylene.

[0011] On the basis of the above scheme, the composite metal oxide component is prepared by the following method:

[0012] ① Add deionized water to a mixture of ammonium heptamolybdate and ammonium metavanadate in a mass ratio of 1:0.4-1:0.09, and stir and dissolve at 60-90°C for 30-60 minutes to obtain a mixed solution I;

[0013] ② Adding ammonium dihydrogen phosphate to mixed solution I to obtain mixed solution II;

[0014] ③ Dissolving cerium nitrate hexahydrate in deionized water to obtain a mixed solution III;

[0015] ④ Add mixed solution III to mixed solution II, stir for 120-130 min, heat to 85-95°C and continue stirring until the reaction solution is evaporated to dryness, and dry the obtained solid material at 80-120°C for 10-12 h;

[0016] ⑤ Grind the solid material dried in step ④, and finally calcine the solid powder at a temperature of 500-600° C. for 2-5 hours at a heating rate of 5° C. / min to obtain the composite metal oxide component.

[0017] On the basis of the above scheme, the solution of the heteropolyacid component is prepared by the following method:

[0018] ① Add deionized water to a mixture of MoO3 and V2O5 in a mass ratio of 1.0:0.06-1.0:0.05, heat at 60-80°C and stir for 20-30 minutes to obtain solution IV;

[0019] ② Add 85% H3PO4 aqueous solution dropwise to solution IV at 90°C, heat with stirring and reflux for 5-7 hours until an orange-red transparent solution V is obtained, then stop refluxing;

[0020] ③ Stir and evaporate the transparent orange-red liquid V obtained above to dryness, and then dry it at 80-120℃ for 10-12h to obtain H4PMo 11 VO 40 ;

[0021] ④ Take H4PMo 11 VO 40 Dissolve in deionized water and stir at 60-80°C to obtain solution VI;

[0022] ⑤ Dissolve CsOH·H2O, KOH and Na2WO4·2H2O in water, slowly add to solution VI and stir for 10 minutes; stir the obtained suspension at 80°C for 3 hours to obtain solution VII, that is, a solution of the heteropolyacid component.

[0023] On the basis of the above scheme, the mass ratio of ammonium heptamolybdate to ammonium dihydrogen phosphate is 1.0:0.5-1.0:0.02; the mass ratio of ammonium heptamolybdate to cerium nitrate hexahydrate is 1.0:0.1-1.0:0.017.

[0024] The catalyst prepared by the above method is used in the preparation of methacrylic acid by one-step oxidation of isobutylene.

[0025] A method for preparing methacrylic acid by one-step oxidation of isobutylene, comprising the following steps:

[0026] The catalyst prepared by the above method was loaded into the constant temperature zone of a quartz glass reaction tube with an inner diameter of 20 mm, an outer diameter of 25 mm, and a length of 45 cm. Quartz wool was placed at both ends of the catalyst in the non-constant temperature zone. The reaction tube was loaded into a tubular furnace reactor. The catalyst bed temperature was set to 360-440°C, the pressure was atmospheric pressure, the feed volume ratio of isobutylene to air was 1:25, and the feed space velocity was 660-1320 h -1 .

[0027] Based on the above solution, the catalyst bed temperature is 400°C.

[0028] On the basis of the above scheme, the feed space velocity is 1320h -1 .

[0029] On the basis of the above scheme, the mass ratio of the composite metal oxide component and the heteropoly acid component in the catalyst is 1:1; the composite metal oxide component is Mo7V3P 0.3 Ce 0.075 O 27 .

[0030] Advantages of the technical solution of the present invention:

[0031] The present invention provides a composite catalyst for preparing methacrylic acid by one-step selective oxidation of isobutylene. By combining a Mo-V series oxide with a modified heteropolyacid catalyst under environmentally friendly conditions, the proportion of strong acid sites in the catalyst is increased, which is beneficial to the selectivity of MAA. The yield of MAA can be improved while maintaining a high conversion rate of isobutylene.

[0032] The catalyst of the present invention has two active components and can directly oxidize isobutylene to methacrylic acid in one step. Compared with the single-component catalyst in the prior art, the two-component composite structure has good thermal stability, high conversion rate and good methacrylic acid selectivity.

[0033] The catalyst of the present invention does not require multi-stage oxidation reactions and can directly oxidize isobutylene into methacrylic acid in one step in a single reactor. This method has a short reaction cycle and process, and the preparation method of the catalyst is simple.

[0034] The catalyst of the present invention is used to prepare methacrylic acid through a one-step oxidation process using isobutylene as a raw material, reducing the complexity of the reaction process and initial equipment costs. The composite catalyst combines asymmetric lattice oxygen with a moderately acidic heteropolyacid catalyst. Ce enhances the oxidizing ability of the active Mo species, promotes oxygen activation to form lattice oxygen, and increases the proportion of medium-to-strong acidic sites in the catalyst. This improves the selectivity for methacrylic acid while maintaining a high isobutylene conversion rate, achieving efficient one-step oxidation of isobutylene to methacrylic acid. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Mo7V3P 0.3 Ce 0.1 O 27 Scanning electron microscopy image of / KCsWPAV composite catalyst;

[0036] Figure 2 Mo7V3P 0.3 Ce 0.1 O 27 X-ray diffraction pattern of / KCsWPAV composite catalyst;

[0037] Figure 3 Mo7V3P 0.3 Ce 0.1 O 27 Infrared spectrum of / KCsWPAV composite catalyst;

[0038] Figure 4 Schematic diagram of the one-step oxidation reaction apparatus for isobutylene. DETAILED DESCRIPTION

[0039] The terms used in the present invention, unless otherwise specified, generally have the meanings commonly understood by those of ordinary skill in the art. Below, in conjunction with specific examples, the present invention will be further described in detail with reference to data. The following examples are merely for illustration of the present invention and are not intended to limit the scope of the present invention in any way.

[0040] Unless otherwise specified, the experimental methods in the following examples are conventional methods and were performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials and reagents used in the following examples, unless otherwise specified, were all commercially available.

[0041] In the following examples, the crystal structure characteristics of the composite catalyst were measured using a Rigaku D / Max 2500 XRD powder analyzer and a Nicolet 8700 Fourier transform infrared (FT-IR) spectrometer manufactured in the United States.

[0042] The present invention uses a chromatograph to perform online analysis of the product, and the conversion rate of isobutylene and the selectivity of methacrylic acid are used as performance indicators for evaluating the catalyst, which are defined as follows:

[0043] Isobutylene conversion = (number of moles of i-C4H8 reacted / number of moles of i-C4H8 supplied as raw material) × 100%

[0044] MAA selectivity = (moles of MAA produced / moles of i-C4H8 reacted) × 100%

[0045] Example 1

[0046] A catalyst for preparing methacrylic acid by a one-step oxidation process of isobutylene is prepared by the following method:

[0047] (1) Preparation of Mo-VP catalyst

[0048] ① Weigh 6.180 g of ammonium heptamolybdate and 1.755 g of ammonium metavanadate into a three-necked flask, add 50 mL of deionized water, place the three-necked flask in a constant temperature magnetic stirrer, and stir at 80°C for about 30 min until the solid matter is completely dissolved to obtain mixed solution I.

[0049] ② Weigh 0.173 g of ammonium dihydrogen phosphate and add it to mixed solution I to obtain mixed solution II;

[0050] ③ Weigh 0.217 g of cerium nitrate hexahydrate and dissolve it in 5 mL of deionized water. Dissolve it in an ultrasonic cleaner to obtain mixed solution III.

[0051] ④ Add mixed solution III to mixed solution II, continue stirring at 80°C for 2 hours, then raise the water bath temperature to 90°C and continue stirring until the reaction liquid in the container is evaporated to dryness. Place the obtained solid material in an electric constant temperature blast drying oven and dry it overnight at a drying temperature of 80°C.

[0052] ⑤ Grind the dried solid using a ceramic mortar, and finally place the solid powder in a ceramic boat and calcine it in a tube furnace. The calcination procedure is calcination at 600℃ for 4 hours with a heating rate of 5℃ / min. The solid powder after calcination is the Mo-VP catalyst, with a composition of Mo7V3P 0.3 Ce 0.1 O 27 .

[0053] (2)Mo7V3P 0.3 Ce 0.1 O 27 Preparation of KCs / WPAV composite catalyst

[0054] ① Weigh 14.400 g of MoO₃ and 0.825 g of V₂O₅ into a 500 mL three-necked flask, add 250 mL of deionized water, and place a magnet. Place the three-necked flask in a constant temperature heated and stirred water bath. Plug the left and right flasks, connect a serpentine condenser to the middle flask, and connect the condenser to tap water. Heat and stir for 20 min to obtain Solution IV. Set the heating temperature to 80°C.

[0055] ②Use a pipette to evenly add 1.048 g of 85% H3PO4 diluted with 10 mL of deionized water dropwise into the three-necked flask, plug the flask, increase the temperature to 90°C, heat and stir under reflux for 5 h until an orange-red transparent solution V is obtained, then stop the reflux.

[0056] ③ Pour the transparent orange-red liquid obtained above into a beaker, wash the three-necked flask and pour the liquid into the beaker together, put in a magnet, stir and evaporate to dryness in a constant temperature water bath at 80℃, take it out and place it in a constant temperature blast drying oven at 80℃ to dry for 12h, and finally obtain bright yellow solid H4PMo 11 VO 40 , abbreviated as HPAV.

[0057] ④ Dissolve 3 g of HPAV solid powder in 100 mL of deionized water and stir at 80°C for 20 min to obtain solution VI.

[0058] ⑤ Then 0.282g of CsOH·H2O, 0.056g of KOH and 0.555g of Na2WO4·2H2O were dissolved in 10mL of water, slowly added to solution VI and stirred for 10min. After that, the suspension was vigorously stirred at 80℃ for 3h to obtain solution VII. 0.6 CsWH 1.4 PMo 11 VO 40 , the heteropolyacid component remains unchanged and is abbreviated as KCsWPAV.

[0059] ⑥Weigh 3.000g Mo7V3P0.3 Ce 0.1 O 27 The catalyst was dissolved in 10 mL of deionized water to obtain solution VIII, which was added to solution VII, and then stirred evenly. The solvent was evaporated by rotary evaporation, and the obtained solid was dried in an oven at 80° C. overnight to obtain a yellow solid.

[0060] ⑦ Grind the dried solid using a ceramic mortar, and finally place the solid powder in a ceramic boat and calcine it in a tube furnace. The calcination procedure is 350℃ for 7h, with a heating rate of 5℃ / min. The solid powder after calcination is Mo7V3P 0.3 Ce 0.1 O 27 / KCsWPAV composite catalyst.

[0061] Two active components Mo7V3P in the catalyst preparation process 0.3 Ce 0.1 O 27 The mass ratio of KCsWPAV is 1:1.

[0062] Mo7V3P prepared by the above method 0.3 Ce 0.1 O 27 The / KCsWPAV composite catalyst was observed by scanning electron microscopy. Figure 1 As shown, Figure 1 The scale bar is 200 nm. The surface of the composite catalyst is dispersed with long flakes and spherical columnar samples, indicating that Mo7V3P 0.3 Ce 0.1 O 27 The / KCsWPAV composite catalyst has the performance characteristics of Mo-V based composite oxide catalyst and heteropolyacid catalyst.

[0063] Mo7V3P 0.3 Ce 0.1 O 27 X-ray diffraction analysis of KCsWPAV composite catalyst Figure 2 As shown, some prominent diffraction peaks correspond to Mo6V9O in the orthorhombic system. 40 The characteristic peaks of the crystal plane indicate that a new material structure has been formed between Mo and V. Based on the structure of Mo6V9O4 determined by powder neutron diffraction, the existence of Mo-OV can be preliminarily inferred indirectly. The diffraction peaks at 2θ=10.56°, 19.9° and 26.14° are similar to those of Keggin structure heteropoly acid H4PMo 11 VO 40 The results are completely consistent, indicating that the finished catalyst has a stable heteropolyacid structure.

[0064] Mo7V3P0.3 Ce 0.1 O 27 Infrared spectrum analysis of / KCsWPAV composite catalyst Figure 3 As shown, at 967cm -1 The peak at 592 cm corresponds to the Mo=O bond. -1 The peak at 500-2000 cm corresponds to the VOV bond, which is characteristic of metal oxides. -1 The catalyst shows the typical IR absorption bands of Keggin structure, which correspond to the P=O bond in the catalytic center, the Mo=O terminal oxygen bond, and the Mo-O b -Mo bridge oxygen bond and intergroup Mo-O c -Mo bridge oxygen bond, these characteristic peaks further indicate that the composite catalyst has the characteristics of Keggin-type structure.

[0065] Example 2

[0066] A catalyst for preparing methacrylic acid by a one-step oxidation process of isobutylene is prepared by the following method:

[0067] Except for the following steps, the remaining steps are the same as those in Example 1.

[0068] (2)Mo7V3P 0.3 Ce 0.1 O 27 Preparation of KCs / WPAV composite catalyst

[0069] ⑥Weigh 4.500g Mo7V3P 0.3 Ce 0.1 O 27 The catalyst was dissolved in 10 mL of deionized water to obtain solution VIII, which was added to solution VII, and then stirred evenly. The solvent was evaporated by rotary evaporation, and the obtained solid was dried in an oven at 80° C. overnight to obtain a yellow solid.

[0070] Two active components Mo7V3P in the catalyst preparation process 0.3 Ce 0.1 O 27 The mass ratio of KCsWPAV is 3:2.

[0071] The catalyst component prepared by the above method is Mo7V3P 0.3 Ce 0.1 O 27 / KCsWPAV.

[0072] Example 3

[0073] A catalyst for preparing methacrylic acid by a one-step oxidation process of isobutylene is prepared by the following method:

[0074] Except for the following steps, the remaining steps are the same as those in Example 1.

[0075] (2)Mo7V3P 0.3 Ce 0.1 O 27 Preparation of KCs / WPAV composite catalyst

[0076] ⑥Weigh 2.000g Mo7V3P 0.3 Ce 0.1 O 27 The catalyst was dissolved in 10 mL of deionized water to obtain solution VIII, which was added to solution VII, and then stirred evenly. The solvent was evaporated by rotary evaporation, and the obtained solid was dried in an oven at 80° C. overnight to obtain a yellow solid.

[0077] Two active components Mo7V3P in the catalyst preparation process 0.3 Ce 0.1 O 27 The mass ratio of KCsWPAV is 2:3.

[0078] The catalyst component prepared by the above method is Mo7V3P 0.3 Ce 0.1 O 27 / KCsWPAV.

[0079] Example 4

[0080] A catalyst for preparing methacrylic acid by a one-step oxidation process of isobutylene is prepared by the following method:

[0081] Except for the following steps, the remaining steps are the same as those in Example 1.

[0082] (2)Mo7V3P 0.3 Ce 0.1 O 27 Preparation of KCs / WPAV composite catalyst

[0083] ⑥Weigh 1.280g Mo7V3P 0.3 Ce 0.1 O 27 The catalyst was dissolved in 10 mL of deionized water to obtain solution VIII, which was added to solution VII, and then stirred evenly. The solvent was evaporated by rotary evaporation, and the obtained solid was dried in an oven at 80° C. overnight to obtain a yellow solid.

[0084] Two active components Mo7V3P in the catalyst preparation process 0.3 Ce 0.1 O 27 The mass ratio of KCsWPAV is 3:7.

[0085] The catalyst component prepared by the above method is Mo7V3P 0.3 Ce 0.1 O 27 / KCsWPAV.

[0086] Example 5

[0087] A catalyst for preparing methacrylic acid by a one-step oxidation process of isobutylene is prepared by the following method:

[0088] Except for the following steps, the remaining steps are the same as those in Example 1.

[0089] (2)Mo7V3P 0.3 Ce 0.1 O 27 Preparation of KCs / WPAV composite catalyst

[0090] ⑥Weigh 0.750g Mo7V3P 0.3 Ce 0.1 O 27 The catalyst was dissolved in 10 mL of deionized water to obtain solution VIII, which was added to solution VII, and then stirred evenly. The solvent was evaporated by rotary evaporation, and the obtained solid was dried in an oven at 80° C. overnight to obtain a yellow solid.

[0091] Two active components Mo7V3P in the catalyst preparation process 0.3 Ce 0.1 O 27 The mass ratio of KCsWPAV is 1:4.

[0092] The catalyst component prepared by the above method is Mo7V3P 0.3 Ce 0.1 O 27 / KCsWPAV.

[0093] Example 6

[0094] A catalyst for preparing methacrylic acid by a one-step oxidation process of isobutylene is prepared by the following method:

[0095] Except for the following steps, the remaining steps are the same as those in Example 1.

[0096] (1) Preparation of Mo-VP catalyst

[0097] ③ Weigh 0.109 g of cerium nitrate hexahydrate and dissolve it in 5 mL of deionized water. Dissolve it in an ultrasonic cleaner to obtain a mixed solution III.

[0098] The catalyst component prepared by the above method is Mo7V3P 0.3 Ce 0.05 O 27 / KCsWPAV.

[0099] Example 7

[0100] A catalyst for preparing methacrylic acid by a one-step oxidation process of isobutylene is prepared by the following method:

[0101] Except for the following steps, the remaining steps are the same as those in Example 1.

[0102] (1) Preparation of Mo-VP catalyst

[0103] ③ Weigh 0.163 g of cerium nitrate hexahydrate and dissolve it in 5 mL of deionized water. Dissolve it in an ultrasonic cleaner to obtain a mixed solution III.

[0104] The catalyst component prepared by the above method is Mo7V3P 0.3 Ce 0.075 O 27 / KCsWPAV.

[0105] Example 8

[0106] A catalyst for preparing methacrylic acid by a one-step oxidation process of isobutylene is prepared by the following method:

[0107] Except for the following steps, the remaining steps are the same as those in Example 1.

[0108] (1) Preparation of Mo-VP catalyst

[0109] ③ Weigh 0.184 g of cerium nitrate hexahydrate and dissolve it in 5 mL of deionized water. Dissolve it in an ultrasonic cleaner to obtain mixed solution III.

[0110] The catalyst component prepared by the above method is Mo7V3P 0.3 Ce 0.085 O 27 / KCsWPAV.

[0111] Example 9

[0112] The method for preparing methacrylic acid by one-step oxidation of isobutylene comprises the following steps:

[0113] 1.000 g of the composite catalyst prepared by the method of Example 1 was loaded into the constant temperature zone of a quartz glass reaction tube with an inner diameter of 20 mm, an outer diameter of 25 mm, and a length of 45 cm. The reaction tube was then loaded into a tubular furnace reactor. A certain amount of quartz wool was placed in the non-constant temperature zone at both ends of the catalyst to ensure that the gaseous reactants passed through the catalyst bed evenly. The catalyst bed temperature was set to 400°C, the pressure was atmospheric pressure, the volume ratio of isobutylene to air was 1:25, and the feed space velocity was 1320 h-1. -1The catalyst was sampled and analyzed after running the reaction for 1 hour. The conversion rate of isobutylene was 90% and the selectivity of methacrylic acid was 50%.

[0114] The process of the above reaction can adopt existing equipment or can adopt Figure 4 The device shown:

[0115] Isobutylene and air flow out of the gas cylinder, and the gas flow is controlled by adjusting the flow meter through the controller. After mixing, they enter the tubular furnace reactor equipped with a catalyst to generate gaseous products containing methacrolein and methacrylic acid. After condensation, the products enter the capture bottle filled with ethanol for collection. The gas components are collected using a gas sampling bag. The whole process is continuous.

[0116] Example 10

[0117] The method for preparing methacrylic acid by one-step oxidation of isobutylene comprises the following steps:

[0118] 1.000 g of the composite catalyst prepared by the method of Example 1 was loaded into the constant temperature zone of a quartz glass reaction tube with an inner diameter of 20 mm, an outer diameter of 25 mm, and a length of 45 cm. The reaction tube was then loaded into a tubular furnace reactor. A certain amount of quartz wool was placed in the non-constant temperature zone at both ends of the catalyst to ensure that the gaseous reactants passed evenly through the catalyst bed. The catalyst bed temperature was set to 360°C, the pressure was atmospheric pressure, the volume ratio of isobutylene to air was 1:25, and the feed space velocity was 1320 h-1. -1 The catalyst was sampled and analyzed after running the reaction for 1 hour. The conversion rate of isobutylene was 93% and the selectivity of methacrylic acid was 25.4%.

[0119] Example 11

[0120] The method for preparing methacrylic acid by one-step oxidation of isobutylene comprises the following steps:

[0121] 1.000 g of the composite catalyst prepared by the method of Example 1 was loaded into the constant temperature zone of a quartz glass reaction tube with an inner diameter of 20 mm, an outer diameter of 25 mm, and a length of 45 cm. The reaction tube was then placed in a tubular furnace reactor. A certain amount of quartz wool was placed in the non-constant temperature zone at both ends of the catalyst to ensure that the gaseous reactants passed through the catalyst bed evenly. The catalyst bed temperature was set to 380°C, the pressure was atmospheric pressure, the volume ratio of isobutylene to air was 1:25, and the feed space velocity was 1320 h-1. -1 After running the reaction for 1 hour, the catalyst was sampled and analyzed, and the conversion rate of isobutylene was 90%, and the selectivity of methacrylic acid was 30.9%.

[0122] Example 12

[0123] The method for preparing methacrylic acid by one-step oxidation of isobutylene comprises the following steps:

[0124] 1.000 g of the composite catalyst prepared by the method of Example 1 was loaded into the constant temperature zone of a quartz glass reaction tube with an inner diameter of 20 mm, an outer diameter of 25 mm, and a length of 45 cm. The reaction tube was then loaded into a tubular furnace reactor. A certain amount of quartz wool was placed in the non-constant temperature zone at both ends of the catalyst to ensure that the gaseous reactants passed through the catalyst bed evenly. The catalyst bed temperature was set to 420°C, the pressure was atmospheric pressure, the volume ratio of isobutylene to air was 1:25, and the feed space velocity was 1320 h-1. -1 After 1 hour of reaction, the catalyst was sampled and analyzed, and the conversion rate of isobutylene was 87% and the selectivity of methacrylic acid was 45.4%.

[0125] Example 13

[0126] The method for preparing methacrylic acid by one-step oxidation of isobutylene comprises the following steps:

[0127] 1.000 g of the composite catalyst prepared by the method of Example 1 was loaded into the constant temperature zone of a quartz glass reaction tube with an inner diameter of 20 mm, an outer diameter of 25 mm, and a length of 45 cm. The reaction tube was then placed in a tubular furnace reactor. A certain amount of quartz wool was placed in the non-constant temperature zone at both ends of the catalyst to ensure that the gaseous reactants passed through the catalyst bed evenly. The catalyst bed temperature was set to 440°C, the pressure was atmospheric pressure, the volume ratio of isobutylene to air was 1:25, and the feed space velocity was 1320 h-1. -1 After 1 hour of reaction, the catalyst was sampled and analyzed, and the conversion rate of isobutylene was 88% and the selectivity of methacrylic acid was 35%.

[0128] Example 14

[0129] The method for preparing methacrylic acid by one-step oxidation of isobutylene comprises the following steps:

[0130] 1.000 g of the composite catalyst prepared by the method of Example 2 was loaded into the constant temperature zone of a quartz glass reaction tube with an inner diameter of 20 mm, an outer diameter of 25 mm, and a length of 45 cm. The reaction tube was then placed in a tubular furnace reactor. A certain amount of quartz wool was placed in the non-constant temperature zone at both ends of the catalyst to ensure that the gaseous reactants passed evenly through the catalyst bed. The catalyst bed temperature was set to 400°C, the pressure was atmospheric pressure, the volume ratio of isobutylene to air was 1:25, and the feed space velocity was 1320 h-1. -1 After 1 hour of reaction, the catalyst was sampled and analyzed, and the conversion rate of isobutylene was 91% and the selectivity of methacrylic acid was 43.6%.

[0131] Example 15

[0132] The method for preparing methacrylic acid by one-step oxidation of isobutylene comprises the following steps:

[0133] 1.000 g of the composite catalyst prepared by the method of Example 3 was loaded into the constant temperature zone of a quartz glass reaction tube with an inner diameter of 20 mm, an outer diameter of 25 mm, and a length of 45 cm. The reaction tube was then placed in a tubular furnace reactor. A certain amount of quartz wool was placed in the non-constant temperature zone at both ends of the catalyst to ensure that the gaseous reactants passed evenly through the catalyst bed. The catalyst bed temperature was set to 400°C, the pressure was atmospheric pressure, the volume ratio of isobutylene to air was 1:25, and the feed space velocity was 1320 h-1. -1 After 1 hour of reaction, the catalyst was sampled and analyzed, and the conversion rate of isobutylene was 90% and the selectivity of methacrylic acid was 25.4%.

[0134] Example 16

[0135] The method for preparing methacrylic acid by one-step oxidation of isobutylene comprises the following steps:

[0136] 1.000 g of the composite catalyst prepared by the method of Example 4 was loaded into the constant temperature zone of a quartz glass reaction tube with an inner diameter of 20 mm, an outer diameter of 25 mm, and a length of 45 cm. The reaction tube was then placed in a tubular furnace reactor. A certain amount of quartz wool was placed in the non-constant temperature zone at both ends of the catalyst to ensure that the gaseous reactants passed evenly through the catalyst bed. The catalyst bed temperature was set to 400°C, the pressure was atmospheric pressure, the volume ratio of isobutylene to air was 1:25, and the feed space velocity was 1320 h-1. -1 After 1 hour of reaction, the catalyst was sampled and analyzed, and the conversion rate of isobutylene was 88% and the selectivity of methacrylic acid was 40.9%.

[0137] Example 17

[0138] The method for preparing methacrylic acid by one-step oxidation of isobutylene comprises the following steps:

[0139] 1.000 g of the composite catalyst prepared by the method of Example 5 was loaded into the constant temperature zone of a quartz glass reaction tube with an inner diameter of 20 mm, an outer diameter of 25 mm, and a length of 45 cm. The reaction tube was then placed in a tubular furnace reactor. A certain amount of quartz wool was placed in the non-constant temperature zone at both ends of the catalyst to ensure that the gaseous reactants passed evenly through the catalyst bed. The catalyst bed temperature was set to 400°C, the pressure was atmospheric pressure, the volume ratio of isobutylene to air was 1:25, and the feed space velocity was 1320 h-1. -1 After 1 hour of reaction, the catalyst was sampled and analyzed, and the conversion rate of isobutylene was 85%, and the selectivity of methacrylic acid was 31.7%.

[0140] Example 18

[0141] The method for preparing methacrylic acid by one-step oxidation of isobutylene comprises the following steps:

[0142] 1.000 g of the composite catalyst prepared by the method of Example 6 was loaded into the constant temperature zone of a quartz glass reaction tube with an inner diameter of 20 mm, an outer diameter of 25 mm, and a length of 45 cm. The reaction tube was then placed in a tubular furnace reactor. A certain amount of quartz wool was placed in the non-constant temperature zone at both ends of the catalyst to ensure that the gaseous reactants passed evenly through the catalyst bed. The catalyst bed temperature was set to 400°C, the pressure was atmospheric pressure, the volume ratio of isobutylene to air was 1:25, and the feed space velocity was 1320 h-1. -1 After 1 hour of reaction, the catalyst was sampled and analyzed, and the conversion rate of isobutylene was 87% and the selectivity of methacrylic acid was 0%.

[0143] Example 19

[0144] The method for preparing methacrylic acid by one-step oxidation of isobutylene comprises the following steps:

[0145] 1.000 g of the composite catalyst prepared by the method of Example 7 was loaded into the constant temperature zone of a quartz glass reaction tube with an inner diameter of 20 mm, an outer diameter of 25 mm, and a length of 45 cm. The reaction tube was then placed in a tubular furnace reactor. A certain amount of quartz wool was placed in the non-constant temperature zone at both ends of the catalyst to ensure that the gaseous reactants passed evenly through the catalyst bed. The catalyst bed temperature was set to 400°C, the pressure was atmospheric pressure, the volume ratio of isobutylene to air was 1:25, and the feed space velocity was 1320 h-1. -1 After running the reaction for 1 hour, the catalyst was sampled and analyzed, and the conversion rate of isobutylene was 93% and the selectivity of methacrylic acid was 80.5%.

[0146] Example 20

[0147] The method for preparing methacrylic acid by one-step oxidation of isobutylene comprises the following steps:

[0148] 1.000 g of the composite catalyst prepared by the method of Example 8 was loaded into the constant temperature zone of a quartz glass reaction tube with an inner diameter of 20 mm, an outer diameter of 25 mm, and a length of 45 cm. The reaction tube was then placed in a tubular furnace reactor. A certain amount of quartz wool was placed in the non-constant temperature zone at both ends of the catalyst to ensure that the gaseous reactants passed evenly through the catalyst bed. The catalyst bed temperature was set to 400°C, the pressure was atmospheric pressure, the volume ratio of isobutylene to air was 1:25, and the feed space velocity was 1320 h-1. -1 After 1 hour of reaction, the catalyst was sampled and analyzed, and the conversion rate of isobutylene was 89% and the selectivity of methacrylic acid was 46.5%.

[0149] Example 21

[0150] The method for preparing methacrylic acid by one-step oxidation of isobutylene comprises the following steps:

[0151] 1.000 g of the composite catalyst prepared by the method of Example 1 was loaded into the constant temperature zone of a quartz glass reaction tube with an inner diameter of 20 mm, an outer diameter of 25 mm, and a length of 45 cm. The reaction tube was then loaded into a tubular furnace reactor. A certain amount of quartz wool was placed in the non-constant temperature zone at both ends of the catalyst to ensure that the gaseous reactants passed through the catalyst bed evenly. The catalyst bed temperature was set to 400°C, the pressure was atmospheric pressure, the volume ratio of isobutylene to air was 1:25, and the feed space velocity was 660 h-1. -1 After 1 hour of reaction, the catalyst was sampled and analyzed, and the conversion rate of isobutylene was 90% and the selectivity of methacrylic acid was 50.7%.

[0152] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other manner. Any person skilled in the art may utilize the above-disclosed technical content to modify or modify the present invention into equivalent embodiments. However, any simple modifications, equivalent variations, and modifications to the above embodiments that do not depart from the technical content of the present invention and are based on the technical essence of the present invention remain within the scope of protection of the present invention.

Claims

1. A catalyst for preparing methacrylic acid by one-step oxidation of isobutylene, characterized in that: Contains a composite metal oxide component and a heteropolyacid component; The composite metal oxide component is prepared by the following method: ① Add deionized water to the mixture of ammonium heptamolybdate and ammonium metavanadate, stir and dissolve to obtain mixed solution I; ② Adding ammonium dihydrogen phosphate to mixed solution I to obtain mixed solution II; ③ Dissolving cerium nitrate hexahydrate in deionized water to obtain a mixed solution III; ④ Add mixed solution III to mixed solution II, stir, and continue stirring after heating until the reaction solution is evaporated to dryness, and dry the obtained solid material overnight; ⑤ Grinding the solid material dried in step ④, and finally calcining the solid powder at 600°C for 4 hours at a heating rate of 5°C / min to obtain the composite metal oxide component; The solution of the heteropolyacid component is prepared by the following method: ① Add deionized water to the mixture of MoO3 and V2O5, heat and stir at 80°C for 20 min to obtain solution IV; ② Add 85% H3PO4 aqueous solution dropwise to solution IV at 90°C, heat with stirring and reflux for 5 h until an orange-red transparent solution V is obtained, then stop refluxing; ③ The transparent orange-red liquid V obtained above was stirred and evaporated to dryness in a constant temperature water bath at 80 ℃, and then dried at 80 ℃ for 12 hours to obtain H4PMo 11 VO 40 ; ④ Take H4PMo 11 VO 40 Dissolve in deionized water and stir at 80 °C for 20 min to obtain solution VI; ⑤ Dissolve CsOH·H2O, KOH and Na2WO4·2H2O in water, slowly add to solution VI and stir for 10 min; stir the obtained suspension at 80°C for 3 h to obtain solution VII, that is, the solution of the heteropolyacid component.

2. The catalyst for preparing methacrylic acid by the one-step oxidation of isobutylene according to claim 1, characterized in that: The mass ratio of the composite metal oxide component to the heteropolyacid component is 3:2-1:

4.

3. The method for preparing a catalyst for preparing methacrylic acid by one-step oxidation of isobutylene according to claim 1 or 2, characterized in that: Here are the steps: An aqueous solution of a composite metal oxide component was added to a solution of a heteropolyacid component, stirred, the solvent evaporated, and dried to obtain a yellow solid. The solid was ground into a powder and calcined at 350°C for 7 h at a heating rate of 5°C / min to obtain a catalyst for the one-step oxidation of isobutylene to methacrylic acid.

4. Use of the catalyst for preparing methacrylic acid by the one-step oxidation of isobutylene according to claim 1 or 2, or the catalyst prepared by the method according to claim 3 in preparing methacrylic acid by the one-step oxidation of isobutylene.

5. A method for preparing methacrylic acid by one-step oxidation of isobutylene, characterized in that: Here are the steps: The catalyst for preparing methacrylic acid by the one-step oxidation of isobutylene according to claim 1 or 2 or the catalyst prepared by the method according to claim 3 is loaded into the constant temperature zone of a quartz glass reaction tube with an inner diameter of 20 mm, an outer diameter of 25 mm, and a length of 45 cm, and quartz wool is placed in the non-constant temperature zone to fill both ends of the catalyst; the reaction tube is loaded into a tubular furnace reactor, and the catalyst bed temperature is set to 360-440°C, the pressure is atmospheric pressure, the feed volume ratio of isobutylene to air is 1:25, and the feed space velocity is 660-1320h -1 .

6. The method for preparing methacrylic acid by one-step oxidation of isobutylene according to claim 5, characterized in that: The catalyst bed temperature is 400°C.

7. The method for preparing methacrylic acid by one-step oxidation of isobutylene according to claim 5, characterized in that: The feed space velocity is 1320h -1 .

8. The method for preparing methacrylic acid by one-step oxidation of isobutylene according to any one of claims 5 to 7, characterized in that: The mass ratio of the composite metal oxide component to the heteropolyacid component in the catalyst is 1:1.

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