Propylene ammoxidation acrylonitrile preparation catalyst with high stability and high byproduct acetonitrile as well as preparation method and application of propylene ammoxidation acrylonitrile preparation catalyst

Abstract

The invention relates to a high-stability catalyst for preparing acrylonitrile through propylene ammoxidation as well as a preparation method and application of the high-stability catalyst. The catalyst comprises an active component and a carrier, the carrier is silicon dioxide, and the active component is composed of Mo, Bi, Fe, a rare earth element, an alkali metal element, an alkaline earth metal element and an element A; (R '+ Q') / (R + Q) of the catalyst is 0.65-0.98, preferably 0.70-0.98, R and Q are respectively peak areas when 2 theta is near 23 degrees + / -0.2 and 25.5 degrees + / -0.2 in X-ray diffraction of the catalyst, and R'and Q 'are respectively peak areas when 2 theta is near 23 degrees + / -0.2 and 25.5 degrees + / -0.2 in X-ray diffraction of the reduced catalyst.

Description

Technical Field

[0001] The present invention relates to the field of catalysis, and more particularly to a catalyst for the ammoxidation of propylene to acrylonitrile with high stability and high by-product acetonitrile, and a preparation method and application thereof. Background Art

[0002] Acrylonitrile (AN) is a raw material monomer for synthesizing acrylic fibers, and is also a raw material for thermoplastic synthetic resins such as ABS and SAN, nitrile rubber, adiponitrile, acrylamide and other derivatives. It is one of the important products in petrochemical industry. The process technology for the production of acrylonitrile by the ammoxidation of propylene has become increasingly mature, and the development of acrylonitrile catalysts with excellent performance has been a hot topic in the acrylonitrile industry.

[0003] At present, the industrial production of the ammoxidation of olefins to unsaturated nitriles still generally adopts the fluidized bed ammoxidation process. As one of the core technologies of this process, the research and improvement of catalysts have always been emphasized. Currently, there are mainly two types of catalysts for the industrial ammoxidation of propylene to acrylonitrile: Mo-Bi series and Sb series. Among them, the Mo-Bi series catalysts dominate, accounting for 95% of the olefin oxidation market. Previous research and exploration have mainly focused on Mo-Bi series catalysts. By introducing metal components with variable valence states such as Fe and Ce elements into the catalyst, the oxidation-reduction performance of the catalyst is improved, and the effective state of the active components of the catalyst is restored more quickly; by introducing metal elements with ionic radii greater than 0.8 nm and less than 0.8 nm, such as Cr, Ni, Mg, Mn, Zn, Al and other elements, the functions of structural and electronic assistants are played to improve the structure and stability of the catalyst; by introducing rare earth elements, the number of lattice oxygen in the catalyst is increased to improve the catalytic performance of the catalyst; by introducing elements such as Cs, Rb, P, B, Al, etc., the surface of the catalyst is modified and the acidity and alkalinity are adjusted to improve the selectivity and activity of the catalyst. In Patent CN110557941A, it is proposed that by controlling the composition and state of specific peaks in X-ray diffraction analysis, the catalyst has a higher ammonia conversion rate and increases the yields of acrylonitrile and hydrogen cyanide as the ammoxidation products of acrylonitrile. In addition, in Patent CN113692315A, it is proposed that by controlling the composition of specific phases in X-ray analysis, the yield of hydrogen cyanide can be increased while suppressing the decrease in the yield of acrylonitrile. However, none of the above analyzes the phases of the catalyst, especially the changes in the phases closely related to the activity of the catalyst during the reaction process. The catalysts of the prior art need to be improved in terms of long-term stable operation and obtaining high propylene conversion rate, and none of them have good performance in terms of the yield of by-product acetonitrile. Therefore, it is necessary to analyze the phases of the catalyst and then prepare a catalyst with high propylene conversion rate during long-term operation. Summary of the Invention

[0004] Aiming at the defects existing in the prior art, the purpose of the present invention is to provide a catalyst for the ammoxidation of propylene to acrylonitrile with high stability and high by-product acetonitrile. This catalyst has the advantages of high propylene conversion rate and high by-product acetonitrile yield during the long-term operation of the catalyst.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A catalyst for the ammoxidation of propylene to acrylonitrile, the catalyst comprising an active component and a carrier, the carrier being silica, and the active component being composed of Mo, Bi, Fe, rare earth elements, alkali metal elements, alkaline earth metal elements and element A.

[0007] The (R'+Q') / (R+Q) of the catalyst is 0.65 to 0.98, preferably 0.70 to 0.98; where R and Q are the peak areas near 2θ of 23°±0.2 and 25.5°±0.2 in the X-ray diffraction of the catalyst respectively, and R' and Q' are the peak areas near 2θ of 23°±0.2 and 25.5°±0.2 in the X-ray diffraction of the reduced catalyst respectively.

[0008] That is to say, after the catalyst of the present invention is reduced, the ratio (R'+Q') / (R+Q) of the peak areas R' and Q' near 2θ of 23°±0.2 and 25.5°±0.2 in the X-ray diffraction to the peak areas R and Q in the fresh catalyst (the catalyst of the present invention before reduction) is 0.65 to 0.98, preferably 0.70 to 0.98.

[0009] The catalyst of the present invention is reduced, and the ratio of the sum of the peak areas near 2θ of 23°±0.2 and 25.5°±0.2 in the X-ray diffraction before and after reduction is investigated, so as to obtain the influence law of the composition change of the key active phase in the catalyst during the reduction process on the activity and stability of the catalyst; the inventor found during the research process that when the (R'+Q') / (R+Q) of the catalyst of the present invention is 0.65 to 0.98, preferably 0.70 to 0.98, the catalyst of the present invention can operate stably for a long time in the reaction of ammoxidation of propylene to acrylonitrile and provide high propylene conversion rate and by-product acetonitrile yield.

[0010] The conditions for the reduction treatment of the above-mentioned catalyst are: under an oxygen-free condition, the catalyst is subjected to in-situ pulse reduction in an atmosphere of propylene and nitrogen;

[0011] Preferably, the conditions for the in-situ pulse reduction are:

[0012] Under anaerobic conditions, 0.1 g of the catalyst was taken for pulse reduction. Propylene and nitrogen were introduced, and the molar ratio of propylene to nitrogen was 0.25. The reaction temperature was 430 °C, and the catalyst load (mass space velocity) was 0.18 h -1 , with a residence time of 0.3 s and an interval of 10 min. Pulse reduction was continued and repeated 10 times in total. After that, it was the catalyst sample after pulse reduction.

[0013] In a preferred technical solution of the present invention, the rare earth element is selected from at least one of La, Ce, Pr, Nd, and Sm, preferably at least one of La, Ce, and Nd; and / or,

[0014] The alkali metal element is selected from at least one of Li, Na, K, Rb, and Cs, preferably K and Rb; and / or,

[0015] The alkaline earth metal element is selected from at least one of Be, Mg, Ca, Sr, and Ba, preferably Mg and Ca; and / or,

[0016] The element A is selected from at least one of W, V, Zr, P, Nb, Ni, Co, Cr, Mn, Tl, Au, Ag, Pt, Ru, Rh, Pd, Ti, Sb, In, Sn, and Te, preferably at least one of W, Zr, P, Nb, Ni, Co, Cr, Ag, Mn, and In.

[0017] In a preferred technical solution of the present invention, based on the weight of the catalyst, the active component is calculated as an oxide, and the content is 30% - 90%, preferably 50 - 70%; the carrier content is 10% - 70%, preferably 30 - 50%.

[0018] Further, in the above technical solution, in the active component, based on the weight of the catalyst particles,

[0019] The weight content of the Mo element calculated as MoO 3 is 15% - 55%, preferably 20% - 45%;

[0020] The weight content of the Bi element calculated as Bi 2 O 3 is 0.5% - 3.5%, preferably 1.0% - 3.5%;

[0021] The weight content of the Fe element calculated as Fe 2 O 3 is 1% - 12%, preferably 1.5% - 11%;

[0022] The weight content of the rare earth element calculated as the oxide of the rare earth element is 1.5% - 8.5%, preferably 2.5% - 5.0%;

[0023] The weight content of the alkali metal element calculated as the oxide is 0.01% - 0.60%, preferably 0.05% - 0.55%;

[0024] The weight content of the alkaline earth metal calculated as the oxide is 0.01% - 4.0%, preferably 0.5% - 3.5%;

[0025] The weight content of the element A calculated as the oxide is 0.01% - 15%, preferably 0.05% - 14%.

[0026] In a preferred technical solution of the present invention, in the active component:

[0027] The atomic ratio of Bi / Mo is 0.008 - 0.25, preferably 0.01 - 0.20;

[0028] The atomic ratio of Fe / Bi is 1.0 - 12.0, preferably 1.5 - 11.0;

[0029] The atomic ratio of the sum of the rare earth element, the alkali metal element and the alkaline earth metal element to Mo is 0.05 - 0.4, preferably 0.10 - 0.35; and / or,

[0030] The atomic ratio of the element A / Mo is 0.01 - 1.0, preferably 0.02 - 0.9. The above specific ratio ranges are conducive to the formation of phases with better catalyst activity in the catalyst.

[0031] The second object of the present invention is to provide a preparation method of a catalyst for ammoxidation of propylene to acrylonitrile with high stability and high by - product acetonitrile, comprising the following steps:

[0032] (1) Mix the precursor of at least one of Fe and the rare earth element in the active component and part of the precursor of Mo, add a dispersant to form a mixed solution I, and perform heat treatment on the mixed solution I;

[0033] (2) Mix the carrier precursor with the remaining Mo precursor to form a mixed solution II;

[0034] (3) Mix the precursors of other active components except those used in the above two steps to form a solution I; add the mixed solution I to the mixed solution II and stir to form a mixed solution III; add the solution I to the mixed solution III to form a slurry I;

[0035] (4) Perform heat treatment on the slurry I and then spray - dry it to obtain particulate matter;

[0036] (5) Calcinate the particulate matter to obtain the catalyst particles.

[0037] This method can further stabilize the active phases during the reaction process. During the coprecipitation process, for example, a precursor of Fe and at least one of rare earth elements such as La and Ce and a part of the Mo precursor first form a mixed solution. By adding a dispersant and performing heat treatment, a eutectic melt structure with stable active phases can be formed in the mixed solution, and then it is added to the mixed solution formed by other elements and the remaining Mo precursor. The above treatment and precipitation processes are beneficial to the formation of uniform active phases in the catalyst and improve the stability of the high-activity crystal phases, which is beneficial to maintaining good stability during the reduction process of the catalyst.

[0038] In the above technical solution, the precursor of the active component is a compound containing the active component element, and the compound is preferably a water-soluble compound, more preferably a water-soluble salt; for example, nitrate, sulfate, hydrochloride, oxalate, etc.

[0039] In the above technical solution, the solvents of the mixed solution and / or the solution are both water. The concentration of the mixed solution and / or the solution is not limited as long as the active component precursor and the support precursor can be fully mixed and dissolved.

[0040] In a preferred technical solution of the present invention, the part of the Mo component in step (1) accounts for 40-80% of the total Mo component, preferably 50-75%. In a preferred technical solution of the present invention, the dispersant in step (1) is selected from at least one of citric acid, acetic acid, oxalic acid, urea, ammonia water, and ethanolamine; and / or,

[0041] The addition amount of the dispersant in step (1) is 0.01-0.2% of the total mass of the catalyst, preferably 0.01-0.15%; and / or,

[0042] The heat treatment conditions of the mixed solution I in step (1) are: heat treatment is carried out at 80-150°C and kept at a constant temperature for 10-30 min; preferably, the heat treatment heating rate is 10-20°C / min.

[0043] In a preferred technical solution of the present invention, the support precursor in step (2) is silica sol, and the solid content of the silica sol is 20 wt%-50 wt% based on silicon dioxide, and the average particle size is 10-35 nm.

[0044] In a preferred technical solution of the present invention, the heat treatment temperature for forming the slurry in step (4) is 60-150°C and kept at a constant temperature for 5-20 min; preferably, the heat treatment heating rate is 8-25°C / min.

[0045] In a preferred technical solution of the present invention, the conditions for spray drying in step (4) include: the drying temperature is 250 - 350 °C, preferably 300 - 350 °C; and / or, the drying time is 0.1 - 2.0 h, preferably 0.2 - 1.0 h; and / or, the average diameter of the spray droplets is 20 - 200 μm, preferably 40 - 180 μm. The drying heat source for spray drying is the drying heat source commonly used in the prior art, such as air.

[0046] In a preferred technical solution of the present invention, the calcination conditions in step (5) include: the calcination temperature is 250 - 700 °C; the calcination time is 30 - 300 min; preferably, it is heated to 250 - 400 °C at a calcination heating rate of 5 - 20 °C / min, held for 10 - 60 min, and then further heated to 400 - 700 °C at a calcination heating rate of 5 - 20 °C / min and held for 20 - 90 min. The calcination atmosphere is the common atmosphere for calcination in the preparation of catalysts in the prior art, such as air.

[0047] The third object of the present invention is to provide the application of the catalyst in the reaction for the ammoxidation of propylene to acrylonitrile. Preferably, the reaction conditions include: the molar ratio of propylene / ammonia / air in terms of O 2 is 1:(1.1 - 1.35):(1.8 - 2.5), the reaction temperature is 420 - 440 °C, the reaction pressure is 0.03 - 0.14 MPa in gauge pressure, and the weight hourly space velocity (catalyst load) is 0.04 - 0.10 h -1 .

[0048] Advantages of the present invention:

[0049] The catalyst of the present invention has a more stable active phase, which is beneficial to maintaining relatively stable reaction performance during the reaction process. When the catalyst of the present invention is applied to the reaction for the ammoxidation of propylene to acrylonitrile, it can have a high propylene conversion rate and a high acetonitrile yield. Description of the drawings

[0050] Figure 1 Shows the XRD patterns of the catalyst before and after the reduction test in Example 1. Detailed implementation manners

[0051] The present invention will be specifically described below in conjunction with specific embodiments. It is necessary to point out here that the following embodiments are only for further illustration of the present invention and cannot be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention still fall within the protection scope of the present invention.

[0052] In addition, it should be noted that, among the various specific technical features described in the following specific embodiments, they can be combined in any appropriate manner without conflict. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0053] In addition, any combination can be made among various different embodiments of the present invention as long as it does not violate the idea of the present invention. The technical solutions thus formed belong to a part of the original public content of this specification and also fall within the protection scope of the present invention.

[0054] Reagent source: All reagents are commercially available.

[0055] Experimental method for pulse reduction of catalyst in specific embodiments:

[0056] Under anaerobic conditions, 0.1 g of catalyst is added to the reactor for pulse reduction. Propylene and nitrogen are introduced, and the gas molar ratio of propylene to nitrogen is 0.25. The reaction temperature is 430 °C, and the catalyst load (mass space velocity) is 0.18 h -1 , the residence time is 0.3 s, with an interval of 10 min, and pulse reduction is continued. After repeating 10 times in total, it is the sample after the pulse reduction experiment.

[0057] XRD of the samples before and after the reduction experiment was performed using an X-ray powder diffractometer from Bruker, Germany, with Cu-K target radiation, a wavelength of 0.15406 nm, a scanning range of 5 - 80°, and a scanning rate of 5° / min.

[0058] In the following examples and comparative examples, the composition of the catalyst was calculated based on the theoretical ratio of the feed amounts.

[0059] Example 1

[0060] Dissolve 581.7 g of (NH 4 ) 6 Mo 7 O 24 ·4H 2 O in water, add 795.5 g of Fe(NO 3 ) 3 ·9H 2 O, 77.1 g of Pr(NO 3 ) 3 ·6H 2 O and 42.6 g of La(NO 3 ) 3 ·6H 2 O and mix them, then add 0.5 g of urea to form mixture I. Heat-treat mixture I at 80 °C with a heating rate of 10 °C / min and keep it at a constant temperature for 10 min. Add 3.63 g of KOH and 173.2 g of Bi(NO3 ) 3 ·5H 2 O, 524.4 g of Ni(NO 3 ) 2 ·6H 2 O, 137.3 g of Mg(NO 3 ) 2 ·6H 2 O are added to water and dissolved to obtain Solution I. 241.7 g of (NH 4 ) 6 Mo 7 O 24 ·4H 2 O is dissolved in water, 2750 g of silica sol with a weight concentration of 40% (average particle size 25 nm) is added, and after stirring for 30 min, a mixed solution II is formed. After adding Solution I and stirring, a mixed solution III is formed. Solution I is continuously added to form Slurry I. Slurry I is heated to 150 °C at a heating rate of 10 °C / min and kept at a constant temperature for 15 min. The prepared slurry is subjected to microsphere granulation in a spray dryer, the drying temperature is 300 °C, the drying time is 0.5 h, and the average diameter of the spray liquid droplets is 100 μm to obtain particulate matter. Finally, it is calcined in an air atmosphere, the calcination heating rate is controlled at 5 °C / min to 300 °C, held for 30 min, and then heated to 550 °C at 20 °C / min and held for 45 min. The composition of the catalyst obtained according to the above steps is represented by the following formula:

[0061] 50% K 0.15 Fe 5.46 Ni 5.0 Mg 1.5 Pr 0.5 La 0.3 Bi 1.0 Mo 13 O x + 50% SiO 2

[0062] The above-obtained catalyst is subjected to a pulse reduction experiment, attached Figure 1 is the XRD pattern of the sample before and after the pulse reduction experiment of Example 1. The ratio (R'+Q') / (R+Q) of the peak areas R' and Q' near 2θ at 23°±0.2 and 25.5°±0.2 to the peak areas R and Q in the fresh catalyst is 0.85.

[0063] The reaction conditions for the ammoxidation of propylene to acrylonitrile using the above-obtained catalyst are as follows: On a millimeter fluidized bed reactor, the catalyst particle size is 50 μm, the reaction temperature: 430 °C; the reaction pressure: 0.084 MPa; the catalyst propylene loading (weight hourly space velocity): 0.085 h -1; Raw material ratio (mole): C 3 ＝ / NH 3 / Air = 1 / 1.25 / 2.0. After running for 1000 hours. The reaction results are as follows: The propylene conversion rate is 99.3%, and the reaction remains stable.

[0064] Example 2

[0065] Dissolve 524.0 g of (NH 4 ) 6 Mo 7 O 24 ·4H 2 O in water, add 803.6 g of Fe(NO 3 ) 3 ·9H 2 O, 78.3 g of Nd(NO 3 ) 3 ·6H 2 O and 42.9 g of La(NO 3 ) 3 ·6H 2 O and mix them, add 1.0 g of urea to form mixture I. Heat-treat mixture I at 100 °C, with a heating rate of 15 °C / min and keep it at a constant temperature for 15 min. Dissolve 3.66 g of KOH, 87.5 g of Bi(NO 3 ) 3 ·5H 2 O, 128.4 g of Mn(NO 3 ) 2 、524.7 g of Co(NO 3 ) 2 ·6H 2 O, 138.7 g of Mg(NO 3 ) 2 ·6H 2 O, 6.09 g of AgNO 3 in water to obtain solution I. Dissolve 307.8 g of (NH 4 ) 6 Mo 7 O 24 ·4H 2O is dissolved in water, and 2750 g of silica sol with a weight concentration of 40% (average particle size 20 nm) is added. After stirring for 30 min, a mixed solution II is formed. After adding mixed solution I and stirring, a mixed solution III is formed. Solution I is continuously added to form slurry I. The slurry I is heated to 120 °C at a heating rate of 10 °C / min and kept at a constant temperature for 15 min. The prepared slurry is subjected to microsphere granulation in a spray dryer, with a drying temperature of 300 °C, a drying time of 0.5 h, and an average spray droplet diameter of 100 μm to obtain particulate matter. Finally, it is calcined in an air atmosphere, with the calcination heating rate controlled at 10 °C / min to 300 °C, staying for 30 min, and then rising to 550 °C at 20 °C / min and staying for 45 min. The composition of the catalyst obtained according to the above steps is represented by the following formula:

[0066] 50% Ag 0.1 K 0.15 Fe 5.46 Co 5.0 Mn 1.0 Mg 1.5 Nd 0.5 La 0.3 Bi 0.5 Mo 13 O x +50% SiO 2

[0067] The above-obtained catalyst is subjected to a pulse reduction experiment. According to the XRD patterns of the sample before and after the pulse reduction experiment, the ratio (R'+Q') / (R+Q) of the peak areas R' and Q' near 2θ at 23°±0.2 and 25.5°±0.2 to the peak areas R and Q in the fresh catalyst is 0.88.

[0068] The reaction conditions for the ammoxidation of propylene to acrylonitrile using the above-obtained catalyst are as follows: On a millimeter fluidized bed reactor, the catalyst particle size is 50 μm, the reaction temperature is 430 °C; the reaction pressure is 0.084 MPa; the catalyst loading is 300 g; the catalyst propylene load (weight hourly space velocity) is 0.085 h -1 ; the raw material ratio (molar): C 3 ＝ / NH 3 / air = 1 / 1.25 / 2.0. After running for 1000 hours, the reaction results are as follows: the propylene conversion rate is 99.0%, and the reaction remains stable.

[0069] Example 3

[0070] 743.5 g of (NH 4 ) 6 Mo 7 O 24 ·4H2 O is dissolved in water, and 1140.1 g of Fe(NO 3 ) 3 ·9H 2 O, 66.6 g of Ce(NO 3 ) 3 ·6H 2 O and 101.6 g of La(NO 3 ) 3 ·6H 2 O are mixed, and 1.5 g of urea is added to form a mixed solution I. The mixed solution I is heat-treated at 120 °C, the heating rate of the heat treatment is 20 °C / min, and it is kept at a constant temperature for 30 min. 11.32 g of RbNO 3 , 124.1 g of Bi(NO 3 ) 3 ·5H 2 O, 744.5 g of Co(NO 3 ) 2 ·6H 2 O, 181.2 g of Ca(NO 3 ) 2 ·6H 2 O, 5.17 g of Cr 2 O 3 , 4.32 g of AgNO 3 are added and dissolved in water to obtain a solution I. 436.6 g of (NH 4 ) 6 Mo 7 O 24 ·4H 2 O is dissolved in water, 1650 g of silica sol with a weight concentration of 40% (average particle size 25 nm) is added, and after stirring for 30 min, a mixed solution II is formed. After adding the mixed solution I and stirring, a mixed solution III is formed. Solution I is continuously added to form a slurry I. The slurry I is heated to 100 °C at a heating rate of 10 °C / min and kept at a constant temperature for 15 min. The prepared slurry is formed into microspheres in a spray dryer, the drying temperature is 300 °C, the drying time is 0.5 h, and the average diameter of the spray droplets is 100 μm to obtain particulate matter. Finally, it is calcined in an air atmosphere, the heating rate of the calcination is controlled at 20 °C / min to 300 °C, held for 30 min, and then heated to 550 °C at 20 °C / min and held for 45 min. The composition of the catalyst obtained according to the above steps is represented by the following formula:

[0071] 70% Ag 0.05 Rb 0.15 Fe 5.46 Co 5.0 Cr 0.1 Ca 1.5 La 0.5 Ce0.3 Bi 0.5 Mo 13 O x + 30% SiO 2

[0072] The obtained catalyst above was subjected to a pulse reduction experiment. According to the XRD patterns of the sample before and after the pulse reduction experiment, the ratio (R'+Q') / (R+Q) of the peak areas R' and Q' at 2θ near 23°±0.2 and 25.5°±0.2 to the peak areas R and Q in the fresh catalyst was 0.90.

[0073] The reaction conditions for the ammoxidation of propylene to acrylonitrile using the obtained catalyst above were as follows: In a millimeter fluidized bed reactor, the catalyst particle size was 50 μm, the reaction temperature was 430 °C; the reaction pressure was 0.084 MPa; the catalyst loading was 300 g; the catalyst propylene load (weight hourly space velocity) was 0.085 h -1 ; The raw material ratio (molar): C 3 ＝ / NH 3 / air = 1 / 1.25 / 2.0. After running for 1000 hours, the reaction results were as follows: the propylene conversion was 98.5%, and the reaction remained stable.

[0074] Example 4

[0075] Dissolve 638.9 g of (NH 4 ) 6 Mo 7 O 24 ·4H 2 O in water, add 979.7 g of Fe(NO 3 ) 3 ·9H 2 O, 38.3 g of Sm(NO 3 ) 3 ·6H 2 O and 52.4 g of La(NO 3 ) 3 ·6H 2 O and mix them. Add 0.5 g of citric acid to form a mixed solution I. Heat-treat the mixed solution I at 80 °C, with a heating rate of 10 °C / min and keep it at a constant temperature for 10 min. Add 9.73 g of RbNO 3 、106.6 g of Bi(NO 3 ) 3 ·5H 2 O, 645.8 g of Ni(NO 3 ) 2 ·6H 2 O, 169.1 g of Mg(NO 3) 2 ·6H 2 O, 4.44 g of Cr 2 O 3 , 11.15 g of AgNO 3 are added to water and dissolved to obtain Solution I. 375.2 g of (NH 4 ) 6 Mo 7 O 24 ·4H 2 O is dissolved in water, 2200 g of silica sol with a weight concentration of 40% (average particle size 25 nm) is added, and after stirring for 30 min, a mixed solution II is formed. After adding Solution I and stirring, a mixed solution III is formed. Solution I is continuously added to form Slurry I. Slurry I is heated to 150 °C at a heating rate of 20 °C / min and kept at a constant temperature for 15 min. The prepared slurry is subjected to microsphere granulation in a spray dryer, the drying temperature is 300 °C, the drying time is 0.5 h, and the average diameter of the spray droplets is 100 μm to obtain particulate matter. Finally, it is calcined in an air atmosphere, the calcination heating rate is controlled at 20 °C / min to 300 °C, held for 20 min, and then heated to 550 °C at 20 °C / min and held for 45 min. The composition of the catalyst obtained according to the above steps is represented by the following formula:

[0076] 60% Ag 0.15 Rb 0.15 Fe 5.46 Ni 5.0 Cr 0.1 Mg 1.5 Sm 0.5 La 0.3 Bi 0.5 Mo 13 O x + 40% SiO 2

[0077] The above-obtained catalyst is subjected to a pulse reduction experiment. According to the XRD patterns of the sample before and after the pulse reduction experiment, the ratio (R'+Q') / (R+Q) of the peak areas R' and Q' near 2θ at 23°±0.2 and 25.5°±0.2 to the peak areas R and Q in the fresh catalyst is 0.81.

[0078] The reaction conditions for the ammoxidation of propylene to acrylonitrile using the above-obtained catalyst are as follows: On a millimeter fluidized bed reactor, the catalyst particle size is 50 μm, the reaction temperature: 430 °C; the reaction pressure: 0.084 MPa; the catalyst loading: 300 g; the catalyst propylene load (weight hourly space velocity): 0.085 h -1 ; Feed ratio (molar): C 3 ＝ / NH 3 / Air = 1 / 1.25 / 2.0. After running for 1000 hours, the reaction results are as follows: the propylene conversion rate is 98.9%, and the reaction remains stable.

[0079] Example 5

[0080] Dissolve 644.6 g of (NH 4 ) 6 Mo 7 O 24 ·4H 2 O in water, and add 988.4 g of Fe(NO 3 ) 3 ·9H 2 O, 38.7 g of Sm(NO 3 ) 3 ·6H 2 O and 38.5 g of Ce(NO 3 ) 3 ·6H 2 O and mix them. Add 0.5 g of oxalic acid to form mixture I. Heat-treat mixture I at 80 °C, with a heating rate of 10 °C / min and keep it at a constant temperature for 10 min. Add 9.81 g of RbNO 3 , 107.6 g of Bi(NO 3 ) 3 ·5H 2 O, 651.5 g of Ni(NO 3 ) 2 ·6H 2 O, 170.6 g of Mg(NO 3 ) 2 ·6H 2 O, 4.48 g of Cr 2 O 3 , 6.64 g of In(NO 3 ) 3 Add them to water and dissolve to obtain solution I. Add 378.5 g of (NH 4 ) 6 Mo 7 O 24 ·4H 2O is dissolved in water, and 2200 g of silica sol with a weight concentration of 40% (average particle size 25 nm) is added. After stirring for 30 min, a mixed solution II is formed. After adding mixed solution I and stirring, a mixed solution III is formed. Solution I is continuously added to form slurry I. The slurry I is heated to 120 °C at a heating rate of 20 °C / min and kept at a constant temperature for 15 min. The prepared slurry is subjected to microsphere granulation in a spray dryer, with a drying temperature of 300 °C, a drying time of 0.5 h, and an average spray droplet diameter of 100 μm to obtain particulate matter. Finally, it is calcined in an air atmosphere. The calcination heating rate is controlled at 20 °C / min to 300 °C, staying for 10 min, and then rising to 550 °C at 20 °C / min and staying for 45 min. The composition of the catalyst obtained according to the above steps is represented by the following formula:

[0081] 60% In 0.05 Rb 0.15 Fe 5.46 Ni 5.0 Cr 0.1 Mg 1.5 Sm 0.5 Ce 0.2 Bi 0.5 Mo 13 O x + 40% SiO 2

[0082] The above-obtained catalyst is subjected to a pulse reduction experiment. According to the XRD patterns of the sample before and after the pulse reduction experiment, the ratio (R'+Q') / (R+Q) of the peak areas R' and Q' near 2θ at 23°±0.2 and 25.5°±0.2 to the peak areas R and Q in the fresh catalyst is 0.83.

[0083] The reaction conditions for the ammoxidation of propylene to acrylonitrile using the above-obtained catalyst are as follows: On a millimeter fluidized bed reactor, the catalyst particle size is 50 μm, the reaction temperature is 430 °C; the reaction pressure is 0.084 MPa; the catalyst loading is 300 g; the catalyst propylene load (weight hourly space velocity) is 0.085 h -1 ; raw material ratio (molar): C 3 ＝ / NH 3 / air = 1 / 1.25 / 2.0. After running for 1000 hours, the reaction results are as follows: the propylene conversion rate is 98.8%, and the reaction remains stable.

[0084] Example 6

[0085] 640.1 g of (NH 4 ) 6 Mo 7 O 24 ·4H2 O is dissolved in water, and 981.5 g of Fe(NO 3 ) 3 ·9H 2 O, 94.9 g of Pr(NO 3 ) 3 ·6H 2 O and 35 g of La(NO 3 ) 3 ·6H 2 O are mixed, and 1.0 g of ammonia water (50%) is added to form a mixed solution I. The mixed solution I is heat-treated at 80 °C, and the heating rate of the heat treatment is 10 °C / min and kept at a constant temperature for 10 min. 6.5 g of RbNO 3 , 106.8 g of Bi(NO 3 ) 3 ·5H 2 O, 647 g of Ni(NO 3 ) 2 ·6H 2 O, 156 g of Ca(NO 3 ) 2 ·6H 2 O, 4.45 g of CrO 3 , 13.18 g of In(NO 3 ) 3 are dissolved in water to obtain a solution I. 375.9 g of (NH 4 ) 6 Mo 7 O 24 ·4H 2 O is dissolved in water, 2200 g of silica sol with a weight concentration of 40% (average particle size 25 nm) is added, and after stirring for 30 min, a mixed solution II is formed. After adding the mixed solution I and stirring, a mixed solution III is formed. Solution I is continuously added to form a slurry I. The slurry I is heated to 100 °C at a heating rate of 20 °C / min and kept at a constant temperature for 15 min. The prepared slurry is formed into microspheres in a spray dryer, the drying temperature is 300 °C, the drying time is 0.5 h, and the average diameter of the spray droplets is 100 μm to obtain particulate matter. Finally, it is calcined in an air atmosphere, the heating rate of the calcination is controlled at 20 °C / min to 300 °C, held for 20 min, and then heated to 550 °C at 20 °C / min and held for 45 min. The composition of the catalyst obtained according to the above steps is represented by the following formula:

[0086] 60% In 0.1 Rb 0.10 Fe 5.46 Ni 5.0 Cr 0.1 Ca 1.5 Pr 0.5 La0.2 Bi 0.5 Mo 13 O x + 40% SiO 2

[0087] The obtained catalyst above was subjected to a pulse reduction experiment. According to the XRD patterns of the sample before and after the pulse reduction experiment, the ratio (R'+Q') / (R+Q) of the peak areas R' and Q' near 2θ at 23°±0.2 and 25.5°±0.2 to the peak areas R and Q in the fresh catalyst was 0.75.

[0088] The reaction conditions for the ammoxidation of propylene to acrylonitrile using the obtained catalyst above were as follows: On a millimeter fluidized bed reactor, the catalyst particle size was 50 microns, the reaction temperature was 430 °C; the reaction pressure was 0.084 MPa; the catalyst loading was 300 g; the catalyst propylene load (weight hourly space velocity) was 0.085 h -1 ; the raw material ratio (molar): C 3 ＝ / NH 3 / air = 1 / 1.25 / 2.0. After running for 1000 hours, the reaction results were as follows: the propylene conversion was 99.0%, and the reaction remained stable.

[0089] Comparative Example 1

[0090] 795.5 g of Fe(NO 3 ) 3 ·9H 2 O, 77.1 g of Pr(NO 3 ) 3 ·6H 2 O, 42.6 g of La(NO 3 ) 3 ·6H 2 O, 3.63 g of KOH, 173.2 g of Bi(NO 3 ) 3 ·5H 2 O, 524.4 g of Ni(NO 3 ) 2 ·6H 2 O, 137.3 g of Mg(NO 3 ) 2 ·6H 2 O were added to water and dissolved to obtain Solution I. 823.4 g of (NH 4 ) 6 Mo 7 O 24 ·4H 2O is dissolved in water, and 2750 g of silica sol with a weight concentration of 40% (average particle size 25 nm) is added. After stirring for 30 min, a mixed solution I is formed. Solution I is added to form slurry I. The slurry I is heated to 150 °C at a heating rate of 10 °C / min and kept at a constant temperature for 15 min. The prepared slurry is subjected to microsphere granulation in a spray dryer. The drying temperature is 300 °C, the drying time is 0.5 h, and the average diameter of the spray droplets is 100 μm to obtain particulate matter. Finally, it is calcined in an air atmosphere. The calcination heating rate is controlled at 5 °C / min to 300 °C, held for 30 min, and then heated to 550 °C at 20 °C / min and held for 45 min. The composition of the catalyst obtained according to the above steps is represented by the following formula:

[0091] 50% K 0.15 Fe 5.46 Ni 5.0 Mg 1.5 Pr 0.5 La 0.3 Bi 1.0 Mo 13 O x +50% SiO 2

[0092] The above-obtained catalyst is subjected to a pulse reduction experiment. According to the XRD patterns of the sample before and after the pulse reduction experiment, the ratio (R'+Q') / (R+Q) of the peak areas R' and Q' near 2θ at 23°±0.2 and 25.5°±0.2 to the peak areas R and Q in the fresh catalyst is 0.60.

[0093] The reaction conditions for the ammoxidation of propylene to acrylonitrile using the above-obtained catalyst are as follows: On a millimeter fluidized bed reactor, the catalyst particle size is 50 μm, the reaction temperature is 430 °C; the reaction pressure is 0.084 MPa; the catalyst loading is 300 g; the catalyst propylene load (weight hourly space velocity) is 0.085 h -1 ; the raw material ratio (molar): C 3 ＝ / NH 3 / air = 1 / 1.25 / 2.0. After running for 1000 h, the reaction results are as follows: the propylene conversion rate is 94.1%.

[0094] Comparative Example 2

[0095] 803.6 g of Fe(NO 3 ) 3 ·9H 2 O, 78.3 g of Nd(NO 3 ) 3 ·6H 2 O, 42.9 g of La(NO 3 )3 ·6H 2 3.66 g of KOH, 87.5 g of Bi(NO 3 ) 3 ·5H 2 O, 128.4 g of Mn(NO 3 ) 2 , 524.7 g of Co(NO 3 ) 2 ·6H 2 O, 138.7 g of Mg(NO 3 ) 2 ·6H 2 O, 6.09 g of AgNO 3 are added to water and dissolved to obtain Solution I. 831.8 g of (NH 4 ) 6 Mo 7 O 24 ·4H 2 O is dissolved in water, 2750 g of silica sol with a weight concentration of 40% (average particle size 20 nm) is added, and after stirring for 30 min, a mixed solution I is formed. Solution I is added to form Slurry I. Slurry I is heated to 150 °C at a heating rate of 10 °C / min and kept at a constant temperature for 15 min. The prepared slurry is subjected to microsphere granulation in a spray dryer, the drying temperature is 300 °C, the drying time is 0.5 h, and the average diameter of the spray droplets is 100 μm to obtain particulate matter. Finally, it is calcined in an air atmosphere, the calcination heating rate is controlled at 10 °C / min to 300 °C, held for 30 min, and then heated to 550 °C at 20 °C / min and held for 45 min. The composition of the catalyst obtained according to the above steps is represented by the following formula:

[0096] 50% Ag 0.1 K 0.15 Fe 5.46 Co 5.0 Mn 1.0 Mg 1.5 Nd 0.5 La 0.3 Bi 0.5 Mo 13 O x +50% SiO 2

[0097] The above-obtained catalyst is subjected to a pulse reduction experiment. According to the XRD patterns before and after the pulse reduction experiment of the sample, the ratio (R'+Q') / (R+Q) of the peak areas R' and Q' near 2θ at 23°±0.2 and 25.5°±0.2 to the peak areas R and Q in the fresh catalyst is 0.62.

[0098] The reaction conditions for the ammoxidation of propylene to acrylonitrile using the above-obtained catalyst are as follows: On a millimeter fluidized bed reactor, the catalyst particle size is 50 microns, the reaction temperature is 430 °C; the reaction pressure is 0.084 MPa; the catalyst loading is 300 grams; the catalyst propylene load (weight hourly space velocity) is 0.085 h-1 -1 ; Feed ratio (molar): C 3 ＝ / NH 3 / Air = 1 / 1.25 / 2.0. After running for 1000 hours, the reaction results are as follows: The propylene conversion rate is 95.7%.

[0099] Comparative Example 3

[0100] Dissolve 581.7 g of (NH 4 ) 6 Mo 7 O 24 ·4H 2 O in water, and add 795.5 g of Fe(NO 3 ) 3 ·9H 2 O, 77.1 g of Pr(NO 3 ) 3 ·6H 2 O and 42.6 g of La(NO 3 ) 3 ·6H 2 O and mix to form a mixed solution I. Dissolve 3.63 g of KOH, 173.2 g of Bi(NO 3 ) 3 ·5H 2 O, 524.4 g of Ni(NO 3 ) 2 ·6H 2 O, 137.3 g of Mg(NO 3 ) 2 ·6H 2 O in water to obtain solution I. Dissolve 241.7 g of (NH 4 ) 6 Mo 7 O 24 ·4H 2O is dissolved in water, and 2750 g of silica sol with a weight concentration of 40% (average particle size 25 nm) is added. After stirring for 30 min, a mixed solution II is formed. After adding mixed solution I and stirring, a mixed solution III is formed. Solution I is continuously added to form slurry I. Slurry I is heated to 150 °C at a heating rate of 10 °C / min and kept at a constant temperature for 15 min. The prepared slurry is subjected to microsphere granulation in a spray dryer, with a drying temperature of 300 °C, a drying time of 0.5 h, and an average spray droplet diameter of 100 μm to obtain particulate matter. Finally, it is calcined in an air atmosphere. The calcination heating rate is controlled at 5 °C / min to 300 °C, held for 30 min, and then heated to 550 °C at 20 °C / min and held for 45 min. The composition of the catalyst obtained according to the above steps is represented by the following formula:

[0101] 50% K 0.15 Fe 5.46 Ni 5.0 Mg 1.5 Pr 0.5 La 0.3 Bi 1.0 Mo 13 O x +50% SiO 2

[0102] The obtained catalyst is subjected to a pulse reduction experiment. According to the XRD before and after the pulse reduction experiment of the sample, the ratio (R'+Q') / (R+Q) of the peak areas R' and Q' near 2θ at 23°±0.2 and 25.5°±0.2 to the peak areas R and Q in the fresh catalyst is 0.63.

[0103] The reaction conditions for the ammoxidation of propylene to acrylonitrile using the obtained catalyst are as follows: On a millimeter fluidized bed reactor, the catalyst particle size is 50 μm, the reaction temperature is 430 °C; the reaction pressure is 0.084 MPa; the catalyst loading is 300 g; the catalyst propylene load (weight hourly space velocity) is 0.085 h -1 ; Feed ratio (molar): C 3 ＝ / NH 3 / air = 1 / 1.25 / 2.0. After running for 1000 hours, the reaction results are as follows: The propylene conversion rate is 95.4%.

[0104] Comparative Example 4

[0105] 581.7 g of (NH 4 ) 6 Mo 7 O 24 ·4H 2 O is dissolved in water, and 795.5 g of Fe(NO 3 )3 ·9H 2 O, 77.1 g of Pr(NO 3 ) 3 ·6H 2 O and 42.6 g of La(NO 3 ) 3 ·6H 2 O were mixed to form mixture I. 3.63 g of KOH, 173.2 g of Bi(NO 3 ) 3 ·5H 2 O, 524.4 g of Ni(NO 3 ) 2 ·6H 2 O, 137.3 g of Mg(NO 3 ) 2 ·6H 2 O were added to water and dissolved to obtain solution I. 241.7 g of (NH 4 ) 6 Mo 7 O 24 ·4H 2 O was dissolved in water, 2750 g of silica sol with a weight concentration of 40% (average particle size 25 nm) was added, and 0.5 g of urea was added to form mixture II. Mixture II was heat-treated at 80 °C, and the heating rate of the heat treatment was 10 °C / min, and it was kept at a constant temperature for 10 min. Mixture I was added to mixture II and stirred to form mixture III. Solution I was continuously added to form slurry I. Slurry I was heated to 150 °C at a heating rate of 10 °C / min and kept at a constant temperature for 15 min. The prepared slurry was formed into microspheres in a spray dryer, the drying temperature was 300 °C, the drying time was 0.5 h, and the average diameter of the spray droplets was 100 μm to obtain particulate matter. Finally, it was calcined in an air atmosphere, the heating rate of the calcination was controlled at 5 °C / min to 300 °C, held for 30 min, and then heated to 550 °C at 20 °C / min and held for 45 min. The composition of the catalyst obtained according to the above steps is represented by the following formula:

[0106] 50% K 0.15 Fe 5.46 Ni 5.0 Mg 1.5 Pr 0.5 La 0.3 Bi 1.0 Mo 13 O x +50% SiO 2

[0107] The obtained catalyst above was subjected to a pulse reduction experiment. According to the XRD patterns of the sample before and after the pulse reduction experiment, the ratio (R'+Q') / (R+Q) of the peak areas R' and Q' near 2θ at 23°±0.2 and 25.5°±0.2 to the peak areas R and Q in the fresh catalyst was 0.64.

[0108] The reaction conditions for the ammoxidation of propylene to acrylonitrile using the obtained catalyst above were as follows: In a millimeter fluidized bed reactor, the catalyst particle size was 50 microns, the reaction temperature was 430 °C, the reaction pressure was 0.084 MPa, the catalyst loading was 300 g, and the catalyst propylene load (weight hourly space velocity) was 0.085 h -1 ; the raw material ratio (molar): C 3 ＝ / NH 3 / air = 1 / 1.25 / 2.0. After running for 1000 hours, the reaction results were as follows: the propylene conversion rate was 95.3%.

[0109] Table 1 Compositions and evaluation results of the catalysts obtained in each example and comparative example

[0110]

[0111] Note: In the above catalyst composition, the X value of O X is the coordination value that satisfies the oxidation states of other elements.

[0112] From the data of the catalyst running for 4 h and the data after running for 1000 h above, it can be seen that the catalyst of the present invention has a more stable active phase, which is beneficial to maintaining relatively stable reaction performance during the reaction process. When the catalyst of the present invention is applied to the reaction of ammoxidation of propylene to acrylonitrile, it can have a high propylene conversion rate and a high acetonitrile yield.

[0113] The present invention has been described in detail above in combination with specific embodiments and exemplary examples, but these descriptions should not be construed as limiting the present invention. Those skilled in the art understand that without departing from the spirit and scope of the present invention, various equivalent substitutions, modifications or improvements can be made to the technical solutions and their implementation manners of the present invention, and these all fall within the scope of the present invention. The protection scope of the present invention is subject to the appended claims.

Claims

1. A catalyst for preparing acrylonitrile by ammoxidation of propylene, comprising an active component and a carrier; the carrier is silicon dioxide, and the active component is composed of Mo, Bi, Fe, rare earth elements, alkali metal elements, alkaline earth metal elements and element A; (R'+Q') / (R+Q) of the catalyst is 0.65-0.98, preferably 0.70-0.98; wherein R and Q are peak areas of 2θ in X-ray diffraction of the catalyst located near 23°±0.2 and 25.5°±0.2, respectively, and R' and Q' are peak areas of 2θ in X-ray diffraction of the catalyst after reduction located near 23°±0.2 and 25.5°±0.2, respectively.

2. The catalyst according to claim 1, characterized in that The rare earth element is selected from at least one of La, Ce, Pr, Nd and Sm, preferably at least one of La, Ce and Nd; and / or, The alkali metal element is selected from at least one of Li, Na, K, Rb and Cs, preferably K and Rb; and / or, The alkaline earth metal element is selected from at least one of Be, Mg, Ca, Sr and Ba, preferably Mg and Ca; and / or, The element A is selected from at least one of W, V, Zr, P, Nb, Ni, Co, Cr, Mn, Tl, Au, Ag, Pt, Ru, Rh, Pd, Ti, Sb, In, Sn and Te, and is preferably at least one of W, Zr, P, Nb, Ni, Co, Cr, Ag, Mn and In.

3. The catalyst according to claim 1, characterized in that Based on the weight of the catalyst, the active component, calculated as oxide, has a content of 30%-90%, preferably 50-70%; the carrier content is 10%-70%, preferably 30-50%.

4. The catalyst according to claim 1, characterized in that The active components, based on the weight of the catalyst, The weight content of the Mo element, calculated as MoO3, is 15%-55%, preferably 20%-45%; and / or, The Bi element is calculated as Bi2O3, and its weight content is 0.5%-3.5%, preferably 1.0%-3.5%; and / or, The Fe element is calculated as Fe2O3, and its weight content is 1%-12%, preferably 1.5%-11%; and / or, The rare earth element, calculated as rare earth element oxide, has a weight content of 1.5% to 8.5%, preferably 2.5% to 5.0%; and / or, The alkali metal element, calculated as oxide, has a weight content of 0.01% to 0.60%, preferably 0.05% to 0.55%; and / or, The alkaline earth metal, calculated as oxide, has a weight content of 0.01% to 4.0%, preferably 0.5% to 3.5%; and / or, The weight content of the element A, calculated as oxide, is 0.01%-15%, preferably 0.05%-14%.

5. The catalyst according to any one of claims 1 to 4, characterized in that Among the active ingredients: The atomic ratio of Bi / Mo is 0.008-0.25, preferably 0.01-0.20; and / or, The atomic ratio of Fe / Bi is 1.0-12.0, preferably 1.5-11.0; and / or, The atomic ratio of the sum of rare earth elements, alkali metal elements and alkaline earth metal elements to Mo is 0.05-0.4, preferably 0.10-0.35; and / or, The atomic ratio of the elements A / Mo is 0.01-1.0, preferably 0.02-0.

9.

6. A method for preparing the catalyst according to any one of claims 1 to 5, comprising the following steps: (1) mixing a precursor of at least one of the Fe and rare earth elements in the active component and a precursor of part of Mo, adding a dispersant to form a mixed solution I, and heat treating the mixed solution I; in; (2) mixing the carrier precursor and the remaining Mo precursor to form a mixed solution II; (3) mixing precursors of other active components except the active components used in the above two steps to form a solution I; Adding mixed solution I into mixed solution II and stirring to form mixed solution III; Adding solution I into mixed solution III to form slurry I; (4) heat-treating the slurry I and then spray-drying it to obtain particles; (5) calcining the particles to obtain the catalyst particles.

7. The preparation method according to claim 6, characterized in that: In step (1), the partial Mo component accounts for 40-80% of the total Mo component, preferably 50-75%; and / or, The dispersant in step (1) is selected from at least one of citric acid, acetic acid, oxalic acid, urea, ammonia water, and ethanolamine; and / or, The amount of the dispersant added in step (1) is 0.01 to 0.2%, preferably 0.01 to 0.15%, of the total mass of the catalyst; and / or The heat treatment conditions of the mixed solution I in step (1) are: heat treatment at 80-150° C. and maintaining the constant temperature for 10-30 min; preferably, the heat treatment heating rate is 10-20° C. / min.

8. The preparation method according to claim 6, characterized in that: The heat treatment temperature of the slurry formed in step (4) is 60-150° C., and the constant temperature is maintained for 5-20 minutes; preferably, the heat treatment heating rate is 8-25° C. / min.

9. The preparation method according to claim 6, characterized in that: The carrier precursor of step (2) is silica sol, the solid content of the silica sol is 20wt%-50wt% in terms of silicon dioxide, and the average particle size is 10-35nm.

10. The preparation method according to claim 6, characterized in that: The precursor of the active component is a compound containing an active component element, and the compound is preferably a water-soluble compound, more preferably a water-soluble salt; and / or, The solvent of the mixed liquid and / or solution is water.

11. The preparation method according to claim 6, characterized in that: The spray drying conditions in step (4) include: a drying temperature of 250-350° C.; preferably 300-350° C.; and / or, The drying time is 0.1-2.0 h, preferably 0.2-1.0 h; and / or, The average diameter of the spray droplets is 20-200 μm, preferably 40-180 μm.

12. The preparation method according to claim 6, characterized in that: The roasting conditions of step (5) include: a roasting temperature of 250-700°C; a roasting time of 30-300 min; preferably, the temperature is increased to 250-400°C at a roasting heating rate of 5-20°C / min, and the temperature is kept for 10-60 min; then the temperature is further increased to 400-700°C at a roasting heating rate of 5-20°C / min, and the temperature is kept for 20-90 min.

13. Use of the catalyst according to any one of claims 1 to 5 or the catalyst prepared by the preparation method according to any one of claims 6 to 12 in the reaction of propylene ammoxidation to produce acrylonitrile; preferably, the reaction conditions include: The molar ratio of propylene / ammonia / air in terms of O2 is 1:(1.1-1.35):(1.8-2.5), the reaction temperature is 420-440°C, the reaction pressure is 0.03-0.14 MPa in terms of gauge pressure, and the weight hourly space velocity is 0.04-0.10 h -1 .

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