Application of composite oxide catalytic material in preparation of concentrated formaldehyde by oxidation of methoxymethane

Abstract

The invention belongs to the technical field of catalytic reaction engineering, and particularly relates to application of a composite oxide catalytic material in preparation of concentrated formaldehyde by oxidation of methoxymethane. According to the invention, a ternary body type composite oxide catalytic material is filled in a tube of a shell-and-tube reactor, so that methoxymethane and oxygen and nitrogen flow through the composite oxide catalytic material in the tube together; methoxymethane and oxygen are subjected to oxidation reaction under the action of the composite oxide catalytic material to be efficiently converted into a product containing high-concentration formaldehyde. Methoxymethane is efficiently oxidized into formaldehyde by using the ternary bulk type composite oxide catalytic material, so that the obtained formaldehyde does not need to be separated or concentrated and can be directly used as a raw material for production of downstream products, and efficient coupling with downstream technologies is facilitated. The method is good in conversion effect, good in product quality, low in comprehensive cost and high in industrial application value.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalytic reaction engineering, and particularly relates to the application of a composite oxide catalytic material in the oxidation of methylal to concentrated formaldehyde. Background Art

[0002] With the growth in demand for products such as resins, coatings, (poly)formaldehyde, polyols, etc., and the rise of chemicals such as polyoxymethylene dimethyl ethers, acrylic acid and its esters, the demand for concentrated formaldehyde, the raw material for the production of these chemicals in China, is increasing day by day.

[0003] As we know, the maximum mass fraction of formaldehyde in the aqueous formaldehyde solution prepared by the methanol oxidation method is 62.5%, while the oxidation of methylal can produce concentrated formaldehyde with a maximum mass fraction of 76.9%. The latter can directly obtain an aqueous formaldehyde solution product with a mass fraction of more than 70% without concentration, which significantly reduces the equipment investment and energy consumption compared with the former (due to the strong association between formaldehyde and water, and the formic acid generated during the heating process will corrode the equipment, so special concentration equipment made of corrosion-resistant materials must be used, and the separation of water is a very energy-consuming process). With the industrial implementation of the technology for directly synthesizing methylal from syngas, compared with the two-step method for synthesizing methylal (syngas is first converted to methanol, and then methanol is dehydrated to produce methylal), this method not only breaks the thermodynamic equilibrium of the syngas-to-methanol reaction, but also shortens the production process flow of methylal. Therefore, the research on the conversion of methylal as a platform molecule to various chemicals has a technical basis and practical significance.

[0004] Although the oxidation of methylal to formaldehyde shows technical and cost advantages in principle compared with the oxidation of methanol to formaldehyde, the oxidation of methylal to formaldehyde has not been industrialized yet, while mature industrial production technologies have been developed for the oxidation of methanol to formaldehyde. The reason is that the conversion efficiency in the process of oxidizing methylal to formaldehyde is relatively low. Summary of the Invention

[0005] To solve the above problems, the present invention provides the application of a composite oxide catalytic material in the oxidation of methylal to concentrated formaldehyde. This (ternary bulk type) composite oxide catalytic material can efficiently catalytically oxidize methylal into a product containing a high concentration of formaldehyde under suitable reaction conditions, and the obtained concentrated formaldehyde can be directly used as the raw material for downstream chemical production.

[0006] To achieve the above invention purposes, the technical solution of the present invention is as follows:

[0007] The present invention protects the application of a composite oxide catalytic material in the oxidation of methylal to concentrated formaldehyde. The composite oxide catalytic material is filled in the tubes of a shell-and-tube reactor, and methylal and oxygen-nitrogen are made to flow through the composite oxide catalytic material in the tubes together. Under the action of the composite oxide catalytic material, methylal and oxygen undergo an oxidation reaction and are efficiently converted into a product containing high-concentration formaldehyde.

[0008] Further, in the above application, the mass fraction of methylal at the reactor inlet is less than 5.4% (specifically, it can be 5.0%, 4.5%, 4.0%, 3.5%, 3.0%, 2.5%, 2.0%, 1.5%, 1.0%, 0.5%, 0.1%, etc.), and the mass fraction of oxygen at the reactor inlet is 8.2% - 23.3% (specifically, it can be 8.2%, 9.0%, 10.0%, 11.0%, 12.0%, 13.0%, 14.0%, 15.0%, 16.0%, 17.0%, 18.0%, 19.0%, 20.0%, 21.0%, 22.0%, 23.0%, 23.3%, etc.).

[0009] Further, in the above application, the wall temperature of the oxidation reaction is 240 - 270 °C (specifically, it can be 240 °C, 250 °C, 260 °C, 270 °C, etc.), the pressure is less than 0.1 MPa, and the space velocity is 6000 - 14000 h -1 (specifically, it can be 6000 h -1 、7000 h -1 、8000 h -1 、9000 h -1 、10000 h -1 、11000 h -1 、12000 h -1 、13000 h -1 、14000 h -1 etc.).

[0010] Further, in the above application, the mass fraction of formaldehyde in the concentrated formaldehyde can reach more than 73%.

[0011] Further, in the above application, the concentrated formaldehyde does not need to be separated or concentrated, and can be directly supplied for the production of downstream chemicals.

[0012] Further, the composite oxide catalytic material is composed of Mo, Fe, X, and O elements, and its chemical formula is Mo α ·Fe β ·X γ ·O δ, where X is Se or Te, α ranges from 0.9 to 3.0 (specifically, it can be 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, etc.), β ranges from 0.6 to 1.5 (specifically, it can be 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, etc.), γ ranges from 0.001 to 0.1 (specifically, it can be 0.001, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, etc.), and δ is a positive number that keeps the algebraic sum of the valences of each element equal to 0.

[0013] Furthermore, the molar ratio of Mo to Fe in the composite oxide catalytic material ranges from 1.50 to 1.74 (specifically, it can be 1.50, 1.51, 1.52, 1.53, 1.54, 1.55, 1.56, 1.57, 1.58, 1.59, 1.60, 1.61, 1.62, 1.63, 1.64, 1.65, 1.66, 1.67, 1.68, 1.69, 1.70, 1.71, 1.72, 1.73, 1.74, etc.).

[0014] Furthermore, the active component of the composite oxide catalytic material is Fe2(MoO4)3, and X is a promoter.

[0015] A preparation method of a ternary bulk composite oxide catalytic material is obtained by a step-by-step wet mixing process. The specific steps are as follows:

[0016] First, a certain amount of industrial-grade MoO3, Fe(NO)3·9H2O, H2SeO4 (SeO2 is also acceptable) or H6TeO6 (TeO3 is also acceptable) are calculated according to atomic stoichiometry and weighed separately; second, Fe(NO)3·9H2O, H2SeO4 (SeO2 is also acceptable) or H6TeO6 (TeO3 is also acceptable) are fully ground and mixed evenly to obtain material A; then, MoO3 is fully ground under the action of a small amount of solvent (methanol, ethanol, ethylene glycol or glycerol) to obtain material B; then A is added to B and fully ground and mixed evenly to obtain material C; finally, C is calcined and formed to obtain a ternary bulk inorganic material Mo α ·Fe β ·X γ ·O δ .

[0017] This step-by-step wet mixing process does not require filtration, washing, or drying, and has fewer steps; the grinding and mixing process is carried out at room temperature, with low energy consumption and short time; no wastewater or solid waste is generated during the whole process, solving the problems of molybdenum loss and iron loss, and being green, economical, and environmentally friendly; the processing cost of the ternary bulk inorganic material with a composite oxide structure is greatly reduced.

[0018] In addition, the crystal water in Fe(NO)3·9H2O is conducive to the full grinding and uniform mixing of Fe(NO)3·9H2O, H2SeO4 (SeO2 is also acceptable) or H6TeO6 (TeO3 is also acceptable); methanol, ethanol, ethylene glycol, or glycerol are all solvents rich in hydroxyl groups. The excellent affinity adsorption of hydroxyl groups not only helps MoO3 to be fully ground and dispersed evenly, but also helps to form a strong interaction between Fe(NO)3·9H2O, H2SeO4 (SeO2 is also acceptable) or H6TeO6 (TeO3 is also acceptable) and the surface of molybdenum trioxide, contributing to the full grinding and uniform mixing of MoO3, Fe(NO)3·9H2O, H2SeO4 (SeO2 is also acceptable) or H6TeO6 (TeO3 is also acceptable), and finally forming a stable and repeatable ternary bulk composite oxide catalytic material Mo α ·Fe β ·X γ ·O δ , so as to give full play to the synergistic effect of each component and improve the activity, selectivity, and stability of the catalyst.

[0019] The technical solution of the present invention has the following beneficial effects compared with the prior art:

[0020] 1. The ternary bulk composite oxide catalytic material Mo α ·Fe β ·X γ ·O δ of the present invention has good dispersion of each component and significant synergistic effect, is suitable for catalytic oxidation of methylal to concentrated formaldehyde, and has the advantages of high activity and good selectivity under suitable reaction processes, with good industrialization prospects.

[0021] 2. The unique formula makes the ternary bulk composite oxide catalytic material perform well when used for methoxymethane oxidation to produce concentrated formaldehyde, wherein the single-pass conversion rate of methoxymethane can reach 100%, and the mass fraction of formaldehyde in concentrated formaldehyde can reach more than 73%. (1) Se or Te in the ternary bulk composite oxide catalytic material is a VIA oxygen group element, with a maximum valence of +6, and can also exist in valences such as -2, -1, 0, +1, +2, and +4. Depending on the environment, these two elements can have variable valences. Se or Te exists in a high-valence state as an auxiliary agent. When the methoxymethane oxidation reaction occurs, Se or Te is reduced to a low-valence state, and then quickly oxidized to a high-valence state by O2 in the reaction gas flow, and the cycle repeats. Se or Te acts as an efficient oxygen carrier to transfer oxygen in the gas flow to the product, and synergizes with Fe2(MoO4)3, which is not only beneficial to the full conversion of methoxymethane, but also beneficial to the conversion of the intermediate product methanol into formaldehyde, thereby improving the raw material conversion rate and product selectivity; (2) The molybdenum-iron ratio of the ternary bulk composite oxide catalyst is relatively low, only 1.50-1.74. This design value ensures that Mo and Fe are fully combined while increasing the mass fraction of the active component Fe2(MoO4)3 in the catalyst material, thereby improving its catalytic performance.

[0022] 3. The mass fraction of formaldehyde in the concentrated formaldehyde of the present invention can reach more than 73%. The concentrated formaldehyde does not need to be further concentrated and can be directly used as a raw material for downstream chemical production, which facilitates the efficient coupling of the technology of the present invention with the downstream formaldehyde production technology.

[0023] 4. The present invention adopts a ternary bulk composite oxide catalytic material with a low molybdenum-to-iron ratio and a low Se or low Te content. The concentrated formaldehyde produced does not need to be concentrated and can be directly put into the production of downstream products. This greatly reduces the equipment cost, three-dose cost, and operating cost of the scheme of the present invention, thereby improving the technical and economic benefits of the scheme of the invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and beneficial effects of the present invention more clear, the present invention is further described in detail below in conjunction with embodiments. All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any way.

[0025] Example 1

[0026] First, weigh 800.0 g, 1393.5 g, and 38.1 g of industrial-grade MoO3, Fe(NO)3·9H2O, and H6TeO6 respectively. Secondly, after mixing the weighed Fe(NO)3·9H2O and H6TeO6, grind them finely and mix evenly to obtain material A. Then, add 225 mL of methanol to the weighed MoO3, mix and grind finely to make it evenly dispersed to obtain material B. Then add A to B, grind finely and mix evenly to obtain material C. Finally, calcine C at 460 °C for 2.5 h and then form it to obtain the ternary bulk composite oxide catalytic material Mo 1.74 ·Fe 1.08 ·Te 0.052 ·O 13.992 。

[0027] Load the catalytic material Mo 1.74 ·Fe 1.08 ·Te 0.052 ·O 13.992 into the reaction tube and control the wall temperature of the reaction tube at 240 °C. Then, let methoxymethane and oxygen flow through the catalytic material Mo 1.74 ·Fe 1.08 ·Te 0.052 ·O 13.992 in the tube. Control the mass fraction of methoxymethane at the inlet of the reaction tube to be 5.3%, the mass fraction of oxygen to be 22.1%, the space velocity to be 14000 h -1 , the pressure to be 0.08 MPa. After the reaction products of methoxymethane and oxygen on Mo 1.74 ·Fe 1.08 ·Te 0.052 ·O 13.992 are absorbed by ethanol, the obtained liquid-phase and gas-phase products are analyzed by chromatography respectively. After calculating the carbon balance, product composition, and catalytic performance indicators, the conversion rate of methoxymethane is 99.6%, the selectivity of formaldehyde is 99.8%, and the mass fraction of formaldehyde in concentrated formaldehyde is 76.0%.

[0028] Example 2

[0029] First, weigh 800.0 g, 1297.2 g, and 26.9 g of industrial-grade MoO3, Fe(NO)3·9H2O, and SeO2 respectively. Secondly, after mixing the weighed Fe(NO)3·9H2O and SeO2, grind them finely and mix evenly to obtain material A. Then, add 135 mL of glycerol to the weighed MoO3, mix and grind finely to make it evenly dispersed to obtain material B. Then add A to B, grind finely and mix evenly to obtain material C. Finally, calcine C at 380 °C for 5.5 h and then form it to obtain the ternary bulk catalytic material with a composite oxide structure Mo 2.25 ·Fe 1.3 ·Te0.098 ·O 8.896 。

[0030] Load the catalytic material Mo 2.25 ·Fe 1.3 ·Te 0.098 ·O 8.896 into the reaction tube, and control the wall temperature of the reaction tube at 270 °C; then let methylal and oxygen-nitrogen flow through the catalytic material Mo 2.25 ·Fe 1.3 ·Te 0.098 ·O 8.896 in the tube. Control the mass fraction of methylal at the inlet of the reaction tube to be 0.3%, the mass fraction of oxygen to be 8.6%, the space velocity to be 6000 h -1 , the pressure to be 0.01 MPa. After the reaction products of methylal and oxygen on Mo 2.25 ·Fe 1.3 ·Te 0.098 ·O 8.896 are absorbed by ethanol, the obtained liquid-phase and gas-phase products are analyzed by chromatography respectively. Through carbon balance, product composition and calculation of catalytic performance indicators, the single-pass conversion rate of methylal is 100%, and the mass fraction of formaldehyde in concentrated formaldehyde is 75.1%.

[0031] Example 3

[0032] First, weigh 800.0 g, 1486.7 g, and 0.9 g of industrial-grade MoO3, Fe(NO)3·9H2O, and TeO3 respectively; secondly, after mixing the weighed Fe(NO)3·9H2O and TeO3, grind them finely and mix them evenly to obtain material A; then, add 324 mL of ethanol to the weighed MoO3, mix them and grind them finely to make them evenly dispersed to obtain material B; then add A to B, grind them finely and mix them evenly to obtain material C; finally, calcine C at 430 °C for 3.5 h and then form it to obtain a ternary bulk-type catalytic material Mo 2.25 ·Fe 1.49 ·Te 0.002 ·O 8.991 。

[0033] Load the catalytic material Mo 2.25 ·Fe 1.49 ·Te 0.002 ·O 8.991 into the reaction tube, and control the wall temperature of the reaction tube at 260 °C; then let methylal and oxygen-nitrogen flow through the catalytic material Mo 2.25 ·Fe 1.49 ·Te 0.002 ·O 8.991, control the mass fraction of methyl methyl ether at the inlet of the reaction tube to be 3.5%, the mass fraction of oxygen to be 17.8%, and the space velocity to be 11,000 h -1 , the pressure is 0.05 MPa. After the reaction products of methyl methyl ether and oxygen on Mo 2.25 ·Fe 1.49 ·Te 0.002 ·O 8.991 are absorbed by ethanol, the obtained liquid-phase and gas-phase products are respectively analyzed by chromatography. After calculating the carbon balance, product composition and catalytic performance indicators, the mass fraction of formaldehyde in concentrated formaldehyde is 73.9%, and the single-pass conversion rate of methyl methyl ether is 99.7%.

[0034] Example 4

[0035] First, weigh 800.0 g, 1458.2 g, and 40.7 g of industrial-grade MoO3, Fe(NO)3·9H2O, and H2SeO4 respectively; secondly, after mixing the weighed Fe(NO)3·9H2O and H2SeO4, grind them finely and mix them evenly to obtain material A; then, add 155 mL of ethylene glycol to the weighed MoO3, mix and grind them finely to make them evenly dispersed to obtain material B; then add A to B, grind them finely and mix them evenly to obtain material C; finally, calcine C at 400 °C for 4.5 h and then form it to obtain a ternary bulk-type catalytic material Mo 0.97 ·Fe 0.63 ·Se 0.049 ·O 3.953 .

[0036] Load the catalytic material Mo 0.97 ·Fe 0.63 ·Se 0.049 ·O 3.953 into the reaction tube and control the wall temperature of the reaction tube to be 250 °C; then let methyl methyl ether and oxygen-nitrogen flow through the catalytic material Mo 0.97 ·Fe 0.63 ·Se 0.049 ·O 3.953 in the tube. Control the mass fraction of methyl methyl ether at the inlet of the reaction tube to be 1.8%, the mass fraction of oxygen to be 12.5%, and the space velocity to be 8,000 h -1 , the pressure is 0.02 MPa. After the reaction products of methyl methyl ether and oxygen on Mo 0.97 ·Fe 0.63 ·Se 0.049 ·O 3.953 are absorbed by ethanol, the obtained liquid-phase and gas-phase products are respectively analyzed by chromatography. After calculating the carbon balance, product composition and catalytic performance indicators, the conversion rate of raw material methyl methyl ether is 99.9%, the selectivity of product formaldehyde is 96.2%, and the mass fraction of formaldehyde in concentrated formaldehyde is 73.2%.

[0037] Comparative Example 1

[0038] First, weigh 800.0 g, 1393.6 g, and 0.4 g of industrial-grade MoO3, Fe(NO)3·9H2O, and H6TeO6 respectively. Secondly, after mixing the weighed Fe(NO)3·9H2O and H6TeO6, grind them finely and mix evenly to obtain Material A. Then, add 225 mL of methanol to the weighed MoO3, mix and grind finely to make it evenly dispersed to obtain Material B. Then add A to B, grind finely and mix evenly to obtain Material C. Finally, after calcining C at 460 °C for 2.5 h, form it to obtain a ternary bulk catalyst material Mo 1.74 ·Fe 1.08 ·Te 0.0005 ·O 6.8415 。

[0039] Load the catalyst material Mo 1.74 ·Fe 1.08 ·Te 0.0005 ·O 6.8415 into the reaction tube, and control the wall temperature of the reaction tube at 340 °C. Then, let methylal and oxygen flow through the catalyst material Mo 1.74 ·Fe 1.08 ·Te 0.0005 ·O 6.8415 in the tube. Control the mass fraction of methylal at the inlet of the reaction tube to be 5.3%, the mass fraction of oxygen to be 22.1%, the space velocity to be 2000 h -1 , the pressure to be 0.08 MPa. After the reaction products of methylal and oxygen on Mo 1.74 ·Fe 1.08 ·Te 0.0005 ·O 6.8415 are absorbed by water, the obtained liquid-phase and gas-phase products are analyzed by chromatography respectively. Through carbon balance, product composition and catalytic performance index calculation, the conversion rate of methylal is 99.3%, the selectivity of the product formaldehyde is 61.6%, and the mass fraction of formaldehyde in concentrated formaldehyde is 47.0%.

[0040] Comparative Example 2

[0041] First, weigh 800.0 g and 1297.2 g of industrial-grade MoO3 and Fe(NO)3·9H2O respectively. Secondly, grind the weighed Fe(NO)3·9H2O finely to obtain Material A. Then, add 135 mL of glycerol to the weighed MoO3, mix and grind finely to make it evenly dispersed to obtain Material B. Then add A to B, grind finely and mix evenly to obtain Material C. Finally, after calcining C at 380 °C for 5.5 h, form it to obtain a ternary bulk catalyst material Mo2.25 ·Fe 1.3 ·O 8.7 。

[0042] Load the catalytic material Mo 2.25 ·Fe 1.3 ·O 8.7 into the reaction tube, and control the wall temperature of the reaction tube at 150 °C; then let methylal and oxygen flow through the catalytic material Mo 2.25 ·Fe 1.3 ·O 8.7 in the tube together. Control the mass fraction of methylal at the inlet of the reaction tube to be 10.0%, the mass fraction of oxygen to be 8.6%, the space velocity to be 6000 h -1 , the pressure to be 0.01 MPa. After the reaction products of methylal and oxygen on Mo 2.25 ·Fe 1.3 ·O 8.7 are absorbed by water, the obtained liquid-phase and gas-phase products are analyzed by chromatography respectively. Through carbon balance, product composition and calculation of catalytic performance indicators, the single-pass conversion rate of raw material methylal is 58.7%, and the mass fraction of formaldehyde in concentrated formaldehyde is 44.3%.

[0043] Comparative Example 3

[0044] First, weigh 1585.7 g, 1486.7 g, and 0.9 g of industrial-grade MoO3, Fe(NO)3·9H2O, and TeO3 respectively; secondly, after mixing the weighed Fe(NO)3·9H2O and TeO3, grind them finely and mix them evenly to obtain Material A; then, add 324 mL of ethanol to the weighed MoO3, mix them and grind them finely to make them evenly dispersed to obtain Material B; then add A to B, grind them finely and mix them evenly to obtain Material C; finally, calcine C at 430 °C for 3.5 h and then form it to obtain a ternary bulk-type catalytic material Mo 4.46 ·Fe 1.49 ·Te 0.002 ·O 15.621 。

[0045] Load the catalytic material Mo 4.46 ·Fe 1.49 ·Te 0.002 ·O 15.621 into the reaction tube, and control the wall temperature of the reaction tube at 260 °C; then let methylal and oxygen flow through the catalytic material Mo 4.46 ·Fe 1.49 ·Te 0.002 ·O 15.621 , control the mass fraction of methylal at the inlet of the reaction tube to be 3.5%, the mass fraction of oxygen to be 30.0%, the space velocity to be 11000 h -1, pressure 0.5 MPa, the reaction products of methylene oxide and oxygen on Mo 4.46 ·Fe 1.49 ·Te 0.002 ·O 15.621 After being absorbed by ethanol, the obtained liquid-phase and gas-phase products were respectively analyzed by chromatography. Through carbon balance, product composition and catalytic performance index calculation, the mass fraction of formaldehyde in concentrated formaldehyde was 67.1%, and the single-pass conversion rate of methylene oxide was 91.5%.

[0046] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. Application of a composite oxide catalytic material in the oxidation of methoxymethane to concentrated formaldehyde, characterized in that: The ternary bulk type composite oxide catalyst material is loaded into the tube of a shell and tube reactor, and methoxymethane and oxygen and nitrogen flow through the composite oxide catalyst material in the tube. Under the action of the composite oxide catalyst material, methoxymethane and oxygen undergo an oxidation reaction and are efficiently converted into a product containing a high concentration of formaldehyde.

2. The use according to claim 1, characterized in that: The mass fraction of methoxymethane at the reactor inlet is lower than 5.4%, and the mass fraction of oxygen at the reactor inlet is 8.2%-23.3%.

3. The use according to claim 1, characterized in that: The wall temperature of the oxidation reaction is 240-270°C, the pressure is lower than 0.1MPa, and the space velocity is 6000-14000h -1 .

4. A composite oxide catalytic material, used in the application of methoxymethane oxidation to concentrated formaldehyde as claimed in any one of claims 1 to 3, characterized in that: The composite oxide catalytic material is composed of Mo, Fe, X, and O elements, and its chemical formula is Mo α ·Fe β ·X γ ·O δ , where X is Se or Te, α is between 0.9 and 3.0, β is between 0.6 and 1.5, γ is between 0.001 and 0.1, and δ is a positive number that keeps the algebraic sum of the valences of the elements equal to 0.

5. The composite oxide catalyst material according to claim 4, characterized in that: The molar ratio of Mo to Fe in the composite oxide catalyst is 1.50-1.

74.

6. The composite oxide catalytic material according to claim 4, characterized in that: The active component of the composite oxide catalytic material is Fe2(MoO4)3, and X is an auxiliary agent.

7. A method for preparing a composite oxide catalyst material as claimed in any one of claims 4 to 6, characterized in that The following steps are involved: 1) MoO3, Fe(NO)3·9H2O, and raw materials containing Se or Te are weighed in proportion, and then fully ground and mixed to obtain material A; 2) Grinding MoO3 fully under the action of a solvent to obtain material B; 3) Add material A to material B, grind them thoroughly and mix them evenly to obtain material C; 4) Calcinate and shape material C to obtain a ternary bulk catalyst having a composite oxide structure, namely, Mo α ·Fe β ·X γ ·O δ .

8. The method for preparing the composite oxide catalyst material according to claim 7, characterized in that: In step 1), the Se-containing raw material is H2SeO4 or SeO2, and the raw material containing TeH6TeO6 or TeO3.

9. The method for preparing the composite oxide catalyst material according to claim 7, characterized in that: The solvent described in step 2) is methanol, ethanol, ethylene glycol or glycerol.

10. The method for preparing the composite oxide catalyst material according to claim 7, characterized in that: The calcination temperature in step 4) is 370-470°C and the calcination time is 2.0-6.0h.