Catalyst for preparing acrylonitrile by propylene ammoxidation with high stability and high by-product acetonitrile, and its preparation and application

Abstract

The present application relates to a kind of propylene ammoxidation preparation acrylonitrile catalyst with high stability and its preparation method and application.The catalyst includes active component and carrier, the carrier is silica, the active component is by Mo, Bi, Fe, rare earth element, alkali metal element, alkaline earth metal element and element A composition;The (R'+Q') / (R+Q) of the catalyst is 0.65~0.98, preferably 0.70~0.98;Wherein R and Q are respectively the peak area in the X-ray diffraction of the catalyst 2 theta located at 23°±0.2 and 25.5°±0.2 around, R' and Q' are respectively the peak area in the X-ray diffraction of the catalyst after reduction 2 theta located at 23°±0.2 and 25.5°±0.2 around.

Description

Technical Field

[0001] This invention relates to the field of catalysis, and more specifically to a catalyst for the ammoxidation of propylene to acrylonitrile with high stability and high by-product acetonitrile, its preparation method, and its application. Background Technology

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

[0003] Currently, the industrial production of unsaturated nitriles from olefins through ammoxidation still widely adopts fluidized bed ammoxidation. Catalysts, as one of the core technologies of this process, have received significant attention for research and improvement. Currently, there are two main types of catalysts for the industrial ammoxidation of propylene to acrylonitrile: Mo-Bi and Sb-based, with Mo-Bi catalysts dominating, accounting for 95% of the olefin oxidation market. Previous research and exploration have primarily focused on Mo-Bi catalysts. Introducing metal components with variable valence states, such as Fe and Ce, into the catalyst can improve its redox performance and accelerate the recovery of the effective state of the active components. Introducing metal elements with ionic radii greater than 0.8 nm and less than 0.8 nm, such as Cr, Ni, Mg, Mn, Zn, and Al, can act as structural and electronic aids, improving the catalyst's structure and stability. Introducing rare earth elements can increase the number of lattice oxygen atoms in the catalyst, improving its catalytic performance. Introducing elements such as Cs, Rb, P, B, and Al can modify the surface of the catalyst and adjust its acidity and basicity, improving its selectivity and activity. Patent CN110557941A proposes that by controlling the composition and state of specific peaks in X-ray diffraction analysis, the catalyst can achieve higher ammonia conversion and improve the yield of acrylonitrile and hydrogen cyanide, which are the products of acrylonitrile ammoxidation. Patent CN113692315A proposes 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 acrylonitrile yield. However, neither of these patents analyzes the phase composition of the catalyst, particularly the changes in phases closely related to catalyst activity during the reaction process. Existing catalysts need improvement in long-term stable operation and achieving high propylene conversion, and neither shows good performance in terms of acetonitrile by-product yield. Therefore, it is necessary to analyze the phase composition of the catalyst to prepare a catalyst that exhibits high propylene conversion during long-term operation. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a catalyst for the ammoxidation of propylene to acrylonitrile with high stability and high by-product acetonitrile yield. This catalyst exhibits advantages such as high propylene conversion rate and high by-product acetonitrile yield during long-term operation.

[0005] To achieve the above objectives, 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 support, wherein the support is silica, and the active component is composed of Mo, Bi, Fe, rare earth elements, alkali metal elements, alkaline earth metal elements and element A.

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

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

[0009] The catalyst of this invention was subjected to reduction treatment, and the sum of the peak areas of 2θ located near 23°±0.2 and 25.5°±0.2 in X-ray diffraction before and after reduction was examined. This revealed the influence of the compositional changes of the key active phase in the catalyst during the reduction process on the catalyst activity and stability. During the research, the inventors found that when the (R'+Q') / (R+Q) ratio of the catalyst of this invention is 0.65 to 0.98, preferably 0.70 to 0.98, the catalyst of this invention can operate stably for a long time in the reaction of propylene ammoxidation to acrylonitrile and provides high propylene conversion and by-product acetonitrile yield.

[0010] The conditions for the reduction treatment of the catalyst described above are: in situ pulse reduction of the catalyst under anaerobic conditions in an atmosphere of propylene and nitrogen;

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

[0012] Under anaerobic conditions, 0.1 g of catalyst was subjected to pulse reduction, with propylene and nitrogen gas introduced at a molar ratio of 0.25. The reaction temperature was 430 °C, and the catalyst loading (mass hourly space velocity) was 0.18 h⁻¹. -1 The residence time was 0.3s, the interval was 10min, and the pulse reduction was repeated 10 times to obtain the catalyst sample after pulse reduction.

[0013] In a preferred embodiment 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 or Rb; and / or,

[0015] The alkaline earth metal element is selected from at least one of Be, Mg, Ca, Sr and Ba, preferably Mg or 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 embodiment of the present invention, based on the weight of the catalyst, the active component, calculated as oxide, has a content of 30%-90%, preferably 50-70%; the support content is 10%-70%, preferably 30-50%.

[0018] Furthermore, in the above technical solution, the active component is defined based on the weight of the catalyst particles.

[0019] The weight content of the Mo element, calculated as MoO3, is 15%-55%, preferably 20%-45%;

[0020] The weight content of Bi element, calculated as Bi2O3, is 0.5%-3.5%, preferably 1.0%-3.5%;

[0021] The Fe element, calculated as Fe2O3, has a weight content of 1%-12%, preferably 1.5%-11%;

[0022] The rare earth element is present in the form of rare earth element oxides with a weight content of 1.5%-8.5%, preferably 2.5%-5.0%;

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

[0024] The alkaline earth metal, calculated as oxides, has a weight content of 0.01%-4.0%, preferably 0.5%-3.5%;

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

[0026] In a preferred embodiment of the present invention, the active component comprises:

[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 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,

[0030] The atomic ratio of element A to Mo is 0.01-1.0, preferably 0.02-0.9. This specific ratio range is beneficial for the formation of a phase with better catalytic activity in the catalyst.

[0031] A second objective of this invention is to provide a method for preparing a catalyst for the 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 rare earth elements in the active component and a portion of the precursor of Mo, add a dispersant to form a mixture I, and heat treat the mixture I.

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

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

[0035] (4) After heat treatment of slurry I, spray drying is performed to obtain particulate matter;

[0036] (5) The particulate matter is roasted to obtain the catalyst particles.

[0037] This method can further stabilize the active phase in the reaction process. During the co-precipitation process, a precursor of Fe and at least one of the rare earth elements such as La and Ce, along with a portion of the Mo precursor, first forms a mixture. By adding a dispersant and performing heat treatment, a eutectic structure with a stable active phase can be formed in the mixture. Then, it is added to the mixture formed by other elements and the remaining Mo precursor. The above treatment and precipitation process is conducive to the formation of a uniform active phase in the catalyst and improves the stability of the highly active crystalline phase, which is beneficial for the catalyst to maintain good stability during the reduction process of the reaction.

[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; such as nitrate, sulfate, hydrochloride, oxalate, etc.

[0039] In the above technical solutions, the solvent for the mixture and / or solution is water. The concentration of the mixture and / or solution is not limited, as long as it allows the active component precursor and the carrier precursor to be fully mixed and dissolved.

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

[0041] The amount of dispersant added 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 for the mixture I in step (1) are as follows: heat treatment at 80-150℃ and constant temperature for 10-30 min; preferably, the heat treatment heating rate is 10-20℃ / min.

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

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

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

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

[0047] A third objective of this invention is to provide an application of the catalyst for the ammoxidation of propylene to acrylonitrile. Preferably, the reaction conditions include: a molar ratio of propylene / ammonia / air (based on O2) of 1:(1.1-1.35):(1.8-2.5), a reaction temperature of 420-440°C, a reaction pressure of 0.03-0.14 MPa (gauge pressure), and a weight hourly space velocity (catalyst loading) of 0.04-0.10 h⁻¹. -1 .

[0048] The beneficial effects of this invention are:

[0049] The catalyst of this invention has a more stable active phase, which is beneficial for maintaining relatively stable reaction performance during the reaction. When applied to the ammoxidation of propylene to acrylonitrile, the catalyst of this invention can achieve high propylene conversion and high acetonitrile yield. Attached Figure Description

[0050] Figure 1 The XRD patterns before and after the catalyst reduction test in Example 1 are shown. Detailed Implementation

[0051] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection 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 are still within the scope of protection of the present invention.

[0052] It should also be noted that the various specific technical features described in the following embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the various possible combinations will not be described separately in this invention.

[0053] Furthermore, various embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention. The resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of the present invention.

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

[0055] Specific implementation method of catalyst pulse reduction experiment:

[0056] Under anaerobic conditions, 0.1 g of catalyst was added to the reactor for pulsed reduction, with propylene and nitrogen gas introduced at a molar ratio of 0.25. The reaction temperature was 430 °C, and the catalyst loading (mass hourly space velocity) was 0.18 h⁻¹. -1 The residence time was 0.3s, the interval was 10min, and the pulse reduction was repeated 10 times to obtain the sample after the pulse reduction experiment.

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

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

[0059] Example 1

[0060] 581.7 grams of (NH4)6Mo7O 24 Dissolve 4H2O in water, add 795.5 g Fe(NO3)3·9H2O, 77.1 g Pr(NO3)3·6H2O, and 42.6 g La(NO3)3·6H2O, mix, and add 0.5 g urea to form mixture I. Heat-treat mixture I at 80℃ with a heating rate of 10℃ / min and maintain the temperature for 10 min. Dissolve 3.63 g KOH, 173.2 g Bi(NO3)3·5H2O, 524.4 g Ni(NO3)2·6H2O, and 137.3 g Mg(NO3)2·6H2O in water to obtain solution I. Add 241.7 g (NH4)6Mo7O 24• 4H₂O was dissolved in water, and 2750 g of silica sol (average particle size 25 nm) with a weight concentration of 40% was added. After stirring for 30 min, mixture II was formed. Mixture I was added and stirred to form mixture III. Solution I was then added to form slurry I. Slurry I was heated to 150 °C at a rate of 10 °C / min and held at that temperature for 15 min. The prepared slurry was then subjected to microsphere forming in a spray dryer at 300 °C for 0.5 h, resulting in an average droplet diameter of 100 μm, yielding particulate matter. Finally, the calcination was carried out in an air atmosphere, with the calcination temperature controlled at 5 °C / min to 300 °C, held for 30 min, and then increased to 550 °C at 20 °C / min, held for 45 min. The composition of the catalyst obtained according to the above steps is expressed 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% SiO2

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

[0063] The reaction conditions for the ammoxidation of propylene to acrylonitrile using the catalyst obtained above are as follows: In a millimeter-sized fluidized bed reactor, the catalyst particle size was 50 micrometers, the reaction temperature was 430℃, the reaction pressure was 0.084 MPa, the catalyst loading was 300 g, and the catalyst propylene loading (weight hourly space velocity) was 0.085 h⁻¹. -1 Raw material ratio (molar): C3 ＝ The ratio of NH3 to air is 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] 524.0 grams of (NH4)6Mo7O 24Dissolve 4H2O in water, add 803.6 g Fe(NO3)3·9H2O, 78.3 g Nd(NO3)3·6H2O, and 42.9 g La(NO3)3·6H2O, mix, and add 1.0 g urea to form mixture I. Heat-treat mixture I at 100℃ with a heating rate of 15℃ / min and maintain the temperature for 15 min. Dissolve 3.66 g KOH, 87.5 g Bi(NO3)3·5H2O, 128.4 g Mn(NO3)2, 524.7 g Co(NO3)2·6H2O, 138.7 g Mg(NO3)2·6H2O, and 6.09 g AgNO3 in water to obtain solution I. Dissolve 307.8 g (NH4)6Mo7O 24 • 4H₂O was dissolved in water, and 2750 g of silica sol with a weight concentration of 40% (average particle size 20 nm) was added. After stirring for 30 min, mixture II was formed. Mixture I was added and stirred to form mixture III. Solution I was then added to form slurry I. Slurry I was heated to 120 °C at a rate of 10 °C / min and held at that temperature for 15 min. The prepared slurry was then subjected to microsphere forming in a spray dryer at a drying temperature of 300 °C for 0.5 h, resulting in an average droplet diameter of 100 μm, thus obtaining particulate matter. Finally, the calcination was carried out in an air atmosphere, with the calcination temperature controlled at 10 °C / min to 300 °C, held for 30 min, and then increased to 550 °C at a rate of 20 °C / min, held for 45 min. The composition of the catalyst obtained according to the above steps is expressed 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% SiO2

[0067] The catalyst obtained 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 of the peak areas R' and Q' of 2θ located near 23°±0.2 and 25.5°±0.2 to the peak areas R and Q in the fresh catalyst (R'+Q') / (R+Q) was 0.88.

[0068] The reaction conditions for the ammoxidation of propylene to acrylonitrile using the catalyst obtained above are as follows: In a millimeter-sized fluidized bed reactor, the catalyst particle size was 50 micrometers, the reaction temperature was 430℃, the reaction pressure was 0.084 MPa, the catalyst loading was 300 g, and the catalyst propylene loading (weight hourly space velocity) was 0.085 h⁻¹. -1 Raw material ratio (molar): C3 ＝ / NH3 / 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 grams of (NH4)6Mo7O 24 Dissolve 4H2O in water, add 1140.1 g Fe(NO3)3·9H2O, 66.6 g Ce(NO3)3·6H2O, and 101.6 g La(NO3)3·6H2O, mix, and add 1.5 g urea to form mixture I. Heat-treat mixture I at 120℃ with a heating rate of 20℃ / min and maintain the temperature for 30 min. Dissolve 11.32 g RbNO3, 124.1 g Bi(NO3)3·5H2O, 744.5 g Co(NO3)2·6H2O, 181.2 g Ca(NO3)2·6H2O, 5.17 g Cr2O3, and 4.32 g AgNO3 in water to obtain solution I. Add 436.6 g (NH4)6Mo7O 24 • 4H₂O was dissolved in water, and 1650 g of silica sol (average particle size 25 nm) with a weight concentration of 40% was added. After stirring for 30 min, mixture II was formed. Mixture I was added and stirred to form mixture III. Solution I was then added to form slurry I. Slurry I was heated to 100 °C at a rate of 10 °C / min and held at that temperature for 15 min. The prepared slurry was then subjected to microsphere forming in a spray dryer at a drying temperature of 300 °C for 0.5 h, resulting in an average droplet diameter of 100 μm, thus obtaining particulate matter. Finally, the calcination was carried out in an air atmosphere, with the calcination temperature controlled at a rate of 20 °C / min to 300 °C, held for 30 min, and then increased to 550 °C at a rate of 20 °C / min, held for 45 min. The composition of the catalyst obtained according to the above steps is expressed 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 Ce 0.3 Bi 0.5 Mo 13 O x +30% SiO2

[0072] The catalyst obtained 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 of the peak areas R' and Q' of 2θ located near 23°±0.2 and 25.5°±0.2 to the peak areas R and Q in the fresh agent (R'+Q') / (R+Q) was 0.90.

[0073] The reaction conditions for the ammoxidation of propylene to acrylonitrile using the catalyst obtained above are as follows: In a millimeter-sized fluidized bed reactor, the catalyst particle size was 50 micrometers, the reaction temperature was 430℃, the reaction pressure was 0.084 MPa, the catalyst loading was 300 g, and the catalyst propylene loading (weight hourly space velocity) was 0.085 h⁻¹. -1 Raw material ratio (molar): C3 ＝ / NH3 / air = 1 / 1.25 / 2.0. After running for 1000 hours, the reaction results are as follows: the propylene conversion rate is 98.5%, and the reaction remains stable.

[0074] Example 4

[0075] 638.9 grams of (NH4)6Mo7O 24 Dissolve 4H2O in water, add 979.7 g Fe(NO3)3·9H2O, 38.3 g Sm(NO3)3·6H2O and 52.4 g La(NO3)3·6H2O, mix, add 0.5 g citric acid to form mixture I. Heat treat mixture I at 80℃ with a heating rate of 10℃ / min and maintain the temperature for 10 min. Dissolve 9.73 g RbNO3, 106.6 g Bi(NO3)3·5H2O, 645.8 g Ni(NO3)2·6H2O, 169.1 g Mg(NO3)2·6H2O, 4.44 g Cr2O3 and 11.15 g AgNO3 in water to obtain solution I. Dissolve 375.2 g (NH4)6Mo7O 24 • 4H₂O was dissolved in water, and 2200 g of silica sol (average particle size 25 nm) with a weight concentration of 40% was added. After stirring for 30 min, mixture II was formed. Mixture I was added and stirred to form mixture III. Solution I was then added to form slurry I. Slurry I was heated to 150 °C at a rate of 20 °C / min and held at that temperature for 15 min. The prepared slurry was then subjected to microsphere forming in a spray dryer at a drying temperature of 300 °C for 0.5 h, resulting in an average droplet diameter of 100 μm, thus obtaining particulate matter. Finally, the calcination was carried out in an air atmosphere, with the calcination temperature controlled at a rate of 20 °C / min to 300 °C, held for 20 min, and then increased to 550 °C at a rate of 20 °C / min, held for 45 min. The composition of the catalyst obtained according to the above steps is expressed 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% SiO2

[0077] The catalyst obtained 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 of the peak areas R' and Q' of 2θ located near 23°±0.2 and 25.5°±0.2 to the peak areas R and Q in the fresh agent (R'+Q') / (R+Q) was 0.81.

[0078] The reaction conditions for the ammoxidation of propylene to acrylonitrile using the catalyst obtained above are as follows: In a millimeter-sized fluidized bed reactor, the catalyst particle size was 50 micrometers, the reaction temperature was 430℃, the reaction pressure was 0.084 MPa, the catalyst loading was 300 g, and the catalyst propylene loading (weight hourly space velocity) was 0.085 h⁻¹. -1 Raw material ratio (molar): C3 ＝ The ratio of NH3 / air is 1 / 1.25 / 2.0. After 1000 hours of operation, the reaction results are as follows: the propylene conversion rate is 98.9%, and the reaction remains stable.

[0079] Example 5

[0080] 644.6 grams of (NH4)6Mo7O 24 Dissolve 4H2O in water, add 988.4 g Fe(NO3)3·9H2O, 38.7 g Sm(NO3)3·6H2O, and 38.5 g Ce(NO3)3·6H2O, mix, and add 0.5 g oxalic acid to form mixture I. Heat-treat mixture I at 80℃ with a heating rate of 10℃ / min and maintain the temperature for 10 min. Dissolve 9.81 g RbNO3, 107.6 g Bi(NO3)3·5H2O, 651.5 g Ni(NO3)2·6H2O, 170.6 g Mg(NO3)2·6H2O, 4.48 g Cr2O3, and 6.64 g In(NO3)3 in water to obtain solution I. Add 378.5 g (NH4)6Mo7O 24• 4H₂O was dissolved in water, and 2200 g of silica sol (average particle size 25 nm) with a weight concentration of 40% was added. After stirring for 30 min, mixture II was formed. Mixture I was added and stirred to form mixture III. Solution I was then added to form slurry I. Slurry I was heated to 120 °C at a rate of 20 °C / min and held at that temperature for 15 min. The prepared slurry was then subjected to microsphere forming in a spray dryer at a drying temperature of 300 °C for 0.5 h, resulting in an average droplet diameter of 100 μm, thus obtaining particulate matter. Finally, the calcination was carried out in an air atmosphere, with the calcination temperature controlled at a rate of 20 °C / min to 300 °C, held for 10 min, and then increased to 550 °C at a rate of 20 °C / min, held for 45 min. The composition of the catalyst obtained according to the above steps is expressed 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% SiO2

[0082] The catalyst obtained 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 of the peak areas R' and Q' of 2θ located near 23°±0.2 and 25.5°±0.2 to the peak areas R and Q in the fresh agent (R'+Q') / (R+Q) was 0.83.

[0083] The reaction conditions for the ammoxidation of propylene to acrylonitrile using the catalyst obtained above are as follows: In a millimeter-sized fluidized bed reactor, the catalyst particle size was 50 micrometers, the reaction temperature was 430℃, the reaction pressure was 0.084 MPa, the catalyst loading was 300 g, and the catalyst propylene loading (weight hourly space velocity) was 0.085 h⁻¹. -1 Raw material ratio (molar): C3 ＝ The ratio of NH3 to air is 1 / 1.25 / 2.0. After 1000 hours of operation, the reaction results are as follows: the propylene conversion rate is 98.8%, and the reaction remains stable.

[0084] Example 6

[0085] 640.1 grams of (NH4)6Mo7O 24Dissolve 4H2O in water, add 981.5 g Fe(NO3)3·9H2O, 94.9 g Pr(NO3)3·6H2O, and 35 g La(NO3)3·6H2O, mix, and add 1.0 g of ammonia (50%) to form mixture I. Heat-treat mixture I at 80℃ with a heating rate of 10℃ / min and maintain the temperature for 10 min. Dissolve 6.5 g RbNO3, 106.8 g Bi(NO3)3·5H2O, 647 g Ni(NO3)2·6H2O, 156 g Ca(NO3)2·6H2O, 4.45 g CrO3, and 13.18 g In(NO3)3 in water to obtain solution I. Dissolve 375.9 g (NH4)6Mo7O 24 • 4H₂O was dissolved in water, and 2200 g of silica sol (average particle size 25 nm) with a weight concentration of 40% was added. After stirring for 30 min, mixture II was formed. Mixture I was added and stirred to form mixture III. Solution I was then added to form slurry I. Slurry I was heated to 100 °C at a rate of 20 °C / min and held at that temperature for 15 min. The prepared slurry was then subjected to microsphere forming in a spray dryer at a drying temperature of 300 °C for 0.5 h, resulting in an average droplet diameter of 100 μm, thus obtaining particulate matter. Finally, the calcination was carried out in an air atmosphere, with the calcination temperature controlled at a rate of 20 °C / min to 300 °C, held for 20 min, and then increased to 550 °C at a rate of 20 °C / min, held for 45 min. The composition of the catalyst obtained according to the above steps is expressed 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 La 0.2 Bi 0.5 Mo 13 O x +40% SiO2

[0087] The catalyst obtained 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 of the peak areas R' and Q' of 2θ located near 23°±0.2 and 25.5°±0.2 to the peak areas R and Q in the fresh agent (R'+Q') / (R+Q) was 0.75.

[0088] The reaction conditions for the ammoxidation of propylene to acrylonitrile using the catalyst obtained above are as follows: In a millimeter-sized fluidized bed reactor, the catalyst particle size was 50 micrometers, the reaction temperature was 430℃, the reaction pressure was 0.084 MPa, the catalyst loading was 300 g, and the catalyst propylene loading (weight hourly space velocity) was 0.085 h⁻¹. -1 Raw material ratio (molar): C3 ＝ / NH3 / 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.

[0089] Comparative Example 1

[0090] Dissolve 795.5 g of Fe(NO3)3·9H2O, 77.1 g of Pr(NO3)3·6H2O, 42.6 g of La(NO3)3·6H2O, 3.63 g of KOH, 173.2 g of Bi(NO3)3·5H2O, 524.4 g of Ni(NO3)2·6H2O, and 137.3 g of Mg(NO3)2·6H2O in water to obtain solution I. Add 823.4 g of (NH4)6Mo7O 24 • 4H₂O was dissolved in water, and 2750 g of silica sol (average particle size 25 nm) with a weight concentration of 40% was added. After stirring for 30 min, a mixture I was formed. Solution I was added to form slurry I. Slurry I was heated to 150 °C at a rate of 10 °C / min and held at that temperature for 15 min. The prepared slurry was then subjected to microsphere forming in a spray dryer at a drying temperature of 300 °C for 0.5 h, resulting in an average droplet diameter of 100 μm, thus obtaining particulate matter. Finally, the calcination was carried out in an air atmosphere, with the calcination temperature controlled at a rate of 5 °C / min to 300 °C, held for 30 min, and then increased to 550 °C at a rate of 20 °C / min, held for 45 min. The composition of the catalyst obtained according to the above steps is expressed 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% SiO2

[0092] The catalyst obtained 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 of the peak areas R' and Q' of 2θ located near 23°±0.2 and 25.5°±0.2 to the peak areas R and Q in the fresh agent (R'+Q') / (R+Q) was 0.60.

[0093] The reaction conditions for the ammoxidation of propylene to acrylonitrile using the catalyst obtained above are as follows: In a millimeter-sized fluidized bed reactor, the catalyst particle size was 50 micrometers, the reaction temperature was 430℃, the reaction pressure was 0.084 MPa, the catalyst loading was 300 g, and the catalyst propylene loading (weight hourly space velocity) was 0.085 h⁻¹. -1 Raw material ratio (molar): C3 ＝ The ratio of NH3 to air is 1 / 1.25 / 2.0. After 1000 hours of operation, the reaction results are as follows: propylene conversion rate is 94.1%.

[0094] Comparative Example 2

[0095] Dissolve 803.6 g Fe(NO3)3·9H2O, 78.3 g Nd(NO3)3·6H2O, 42.9 g La(NO3)3·6H2O, 3.66 g KOH, 87.5 g Bi(NO3)3·5H2O, 128.4 g Mn(NO3)2, 524.7 g Co(NO3)2·6H2O, 138.7 g Mg(NO3)2·6H2O, and 6.09 g AgNO3 in water to obtain solution I. Dissolve 831.8 g (NH4)6Mo7O 24 • 4H₂O was dissolved in water, and 2750 g of silica sol (average particle size 20 nm) with a weight concentration of 40% was added. After stirring for 30 min, a mixture I was formed. Solution I was added to form slurry I. Slurry I was heated to 150 °C at a rate of 10 °C / min and held at that temperature for 15 min. The prepared slurry was then subjected to microsphere forming in a spray dryer at a drying temperature of 300 °C for 0.5 h, resulting in an average droplet diameter of 100 μm, thus obtaining particulate matter. Finally, the calcination was carried out in an air atmosphere, with the calcination temperature controlled at a rate of 10 °C / min to 300 °C, held for 30 min, and then increased to 550 °C at a rate of 20 °C / min, held for 45 min. The composition of the catalyst obtained according to the above steps is expressed 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% SiO2

[0097] The catalyst obtained 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 of the peak areas R' and Q' of 2θ located near 23°±0.2 and 25.5°±0.2 to the peak areas R and Q in the fresh catalyst (R'+Q') / (R+Q) was 0.62.

[0098] The reaction conditions for the ammoxidation of propylene to acrylonitrile using the catalyst obtained above are as follows: In a millimeter-sized fluidized bed reactor, the catalyst particle size was 50 micrometers, the reaction temperature was 430℃, the reaction pressure was 0.084 MPa, the catalyst loading was 300 g, and the catalyst propylene loading (weight hourly space velocity) was 0.085 h⁻¹. -1 Raw material ratio (molar): C3 ＝ The ratio of NH3 to air is 1 / 1.25 / 2.0. After 1000 hours of operation, the reaction results are as follows: propylene conversion rate is 95.7%.

[0099] Comparative Example 3

[0100] 581.7 grams of (NH4)6Mo7O 24 Dissolve 4H2O in water, then add 795.5 g of Fe(NO3)3·9H2O, 77.1 g of Pr(NO3)3·6H2O, and 42.6 g of La(NO3)3·6H2O to form mixed solution I. Dissolve 3.63 g of KOH, 173.2 g of Bi(NO3)3·5H2O, 524.4 g of Ni(NO3)2·6H2O, and 137.3 g of Mg(NO3)2·6H2O in water to obtain solution I. Dissolve 241.7 g of (NH4)6Mo7O 24 • 4H₂O was dissolved in water, and 2750 g of silica sol (average particle size 25 nm) with a weight concentration of 40% was added. After stirring for 30 min, mixture II was formed. Mixture I was added and stirred to form mixture III. Solution I was then added to form slurry I. Slurry I was heated to 150 °C at a rate of 10 °C / min and held at that temperature for 15 min. The prepared slurry was then subjected to microsphere forming in a spray dryer at 300 °C for 0.5 h, resulting in an average droplet diameter of 100 μm, yielding particulate matter. Finally, the calcination was carried out in an air atmosphere, with the calcination temperature controlled at 5 °C / min to 300 °C, held for 30 min, and then increased to 550 °C at 20 °C / min, held for 45 min. The composition of the catalyst obtained according to the above steps is expressed 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% SiO2

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

[0103] The reaction conditions for the ammoxidation of propylene to acrylonitrile using the catalyst obtained above are as follows: In a millimeter-sized fluidized bed reactor, the catalyst particle size was 50 micrometers, the reaction temperature was 430℃, the reaction pressure was 0.084 MPa, the catalyst loading was 300 g, and the catalyst propylene loading (weight hourly space velocity) was 0.085 h⁻¹. -1 Raw material ratio (molar): C3 ＝ The ratio of NH3 to air is 1 / 1.25 / 2.0. After 1000 hours of operation, the reaction results are as follows: propylene conversion rate is 95.4%.

[0104] Comparative Example 4

[0105] 581.7 grams of (NH4)6Mo7O 24 Dissolve 4H2O in water, then add 795.5 g of Fe(NO3)3·9H2O, 77.1 g of Pr(NO3)3·6H2O, and 42.6 g of La(NO3)3·6H2O to form mixed solution I. Dissolve 3.63 g of KOH, 173.2 g of Bi(NO3)3·5H2O, 524.4 g of Ni(NO3)2·6H2O, and 137.3 g of Mg(NO3)2·6H2O in water to obtain solution I. Dissolve 241.7 g of (NH4)6Mo7O 24 • 4H₂O was dissolved in water, and 2750 g of silica sol (average particle size 25 nm) with a weight concentration of 40% was added. 0.5 g of urea was added to form mixture II. Mixture II was heat-treated at 80 °C at a heating rate of 10 °C / min and held at this temperature for 10 min. Mixture I was added to mixture II and stirred to form mixture III. Solution I was then added to form slurry I. Slurry I was heated to 150 °C at a heating rate of 10 °C / min and held at this temperature for 15 min. The prepared slurry was then subjected to microsphere forming in a spray dryer at 300 °C for 0.5 h, resulting in an average droplet diameter of 100 μm, yielding particulate matter. Finally, the calcination was carried out in an air atmosphere, with the heating rate controlled at 5 °C / min to 300 °C, held for 30 min, then increased at 20 °C / min to 550 °C, held for 45 min. The composition of the catalyst obtained according to the above steps is expressed by the following formula:

[0106] 50% K 0.15 Fe 5.46 Ni 5.0Mg 1.5 Pr 0.5 La 0.3 Bi 1.0 Mo 13 O x +50% SiO2

[0107] The catalyst obtained 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 of the peak areas R' and Q' of 2θ located near 23°±0.2 and 25.5°±0.2 to the peak areas R and Q in the fresh catalyst (R'+Q') / (R+Q) was 0.64.

[0108] The reaction conditions for the ammoxidation of propylene to acrylonitrile using the catalyst obtained above are as follows: In a millimeter-sized fluidized bed reactor, the catalyst particle size was 50 micrometers, the reaction temperature was 430℃, the reaction pressure was 0.084 MPa, the catalyst loading was 300 g, and the catalyst propylene loading (weight hourly space velocity) was 0.085 h⁻¹. -1 Raw material ratio (molar): C3 ＝ The ratio of NH3 to air is 1 / 1.25 / 2.0. After 1000 hours of operation, the reaction results are as follows: propylene conversion rate is 95.3%.

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

[0110]

[0111] Note: O in the above catalyst composition X The X value is the coordination value that satisfies the oxidation state of other elements.

[0112] The data from 4 hours and 1000 hours of catalyst operation show that the catalyst of this invention has a more stable active phase, which is beneficial for maintaining stable reaction performance during the reaction. When applied to the ammoxidation of propylene to acrylonitrile, the catalyst of this invention can achieve high propylene conversion and high acetonitrile yield.

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

Claims

1. A catalyst for the ammoxidation of propylene to acrylonitrile, comprising an active component and a support; wherein the support is silica, and the active component is composed of Mo, Bi, Fe, rare earth elements, alkali metal elements, alkaline earth metal elements, and element A; the (R'+Q') / (R+Q) ratio of the catalyst is 0.65~0.98; wherein R and Q are the peak areas of 2θ at approximately 23º±0.2 and 25.5º±0.2 in the X-ray diffraction of the catalyst, respectively, and R' and Q' are the peak areas of 2θ at approximately 23º±0.2 and 25.5º±0.2 in the X-ray diffraction of the reduced catalyst, respectively; 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; Based on the weight of the catalyst, The Mo element, calculated as MoO3, has a weight content of 15%-55%. The Bi element, calculated as Bi2O3, has a weight content of 0.5%-3.5%. The Fe element, calculated as Fe2O3, has a weight content of 1%-12%; The rare earth elements, calculated as oxides of rare earth elements, have a weight content of 1.5%-8.5%; The alkali metal element, calculated as oxide, has a weight content of 0.01%-0.60%; The alkaline earth metal, calculated as oxides, has a weight content of 0.01%-4.0%; The element A, calculated as an oxide, has a weight content of 0.01%-15%.

2. The catalyst according to claim 1, characterized in that... The catalyst has a (R'+Q') / (R+Q) ratio of 0.70 to 0.

98.

3. 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; and / or, The alkali metal element is selected from at least one of Li, Na, K, Rb, and Cs; and / or, The alkaline earth metal element is selected from at least one of Be, Mg, Ca, Sr, and Ba; and / or, The element A is at least one of W, Zr, P, Nb, Ni, Co, Cr, Ag, Mn and In.

4. The catalyst according to claim 3, characterized in that... The rare earth element is at least one of La, Ce, and Nd; and / or, The alkali metal element is K, Rb; and / or, The alkaline earth metal elements are Mg and Ca.

5. 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%; the support has a content of 10%-70%.

6. The catalyst according to claim 5, characterized in that, Based on the weight of the catalyst, the active component, calculated as oxide, has a content of 50-70%; the support has a content of 30-50%.

7. The catalyst according to claim 1, characterized in that, Of the active components, the amount is based on the weight of the catalyst. The Mo element, calculated as MoO3, has a weight content of 20%-45%; and / or, The Bi element, calculated as Bi₂O₃, has a weight content of 1.0%-3.5%; and / or, The Fe element, calculated as Fe2O3, has a weight content of 1.5%-11%; and / or, The rare earth elements, calculated as oxides of rare earth elements, have a weight content of 2.5%-5.0%; and / or, The alkali metal element, calculated as an oxide, has a weight content of 0.05%-0.55%; and / or, The alkaline earth metal, calculated as oxides, has a weight content of 0.5%-3.5%; and / or, The element A, calculated as an oxide, has a weight content of 0.05%-14%.

8. The catalyst according to claim 1, characterized in that, In the active component: The atomic ratio of Bi / Mo is 0.008-0.25; and / or, The atomic ratio of Fe / Bi is 1.0-12.0; 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; and / or, The atomic ratio of element A to Mo is 0.01-1.

0.

9. The catalyst according to claim 8, characterized in that, In the active component: The atomic ratio of Bi / Mo is 0.01-0.20; and / or, The atomic ratio of Fe / Bi is 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 0.10-0.35; and / or, The atomic ratio of element A to Mo is 0.02-0.

9.

10. A method for preparing the catalyst according to any one of claims 1-9, comprising the following steps: (1) Mix the precursor of at least one of Fe and rare earth elements in the active component and a portion of the precursor of Mo, add a dispersant to form a mixture I, and heat treat the mixture I. in; (2) Mix the carrier precursor with the remaining Mo precursor to form mixture II; (3) Mix the precursors of other active components besides those used in the above two steps to form solution I; Mixture I is added to mixture II and stirred to form mixture III; Solution I is added to mixture III to form slurry I; (4) After heat treatment, slurry I is spray-dried to obtain particulate matter; (5) The particulate matter is calcined to obtain the catalyst particles.

11. The preparation method according to claim 10, characterized in that, In step (1), a portion of the Mo component accounts for 40-80% of the total Mo component; and / or, The dispersant in step (1) is selected from at least one of citric acid, acetic acid, oxalic acid, urea, ammonia, and ethanolamine; and / or, The amount of dispersant added in step (1) is 0.01~0.2% of the total mass of the catalyst; and / or, The heat treatment conditions for the mixture I in step (1) are: heat treatment at 80-150℃ and constant temperature for 10-30 minutes.

12. The preparation method according to claim 11, characterized in that, In step (1), a portion of the Mo component accounts for 50-75% of the total Mo component; and / or, The amount of dispersant added in step (1) is 0.01~0.15% of the total mass of the catalyst; and / or, In step (1), the heat treatment heating rate is 10~20℃ / min.

13. The preparation method according to claim 10, characterized in that, The heat treatment temperature for forming the slurry in step (4) is 60~150℃, and the temperature is kept constant for 5~20 minutes.

14. The preparation method according to claim 13, characterized in that, In step (4), the heat treatment heating rate is 8~25℃ / min.

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

16. The preparation method according to claim 10, characterized in that, The precursor of the active component is a compound containing the active component element; and / or, The solvent for the mixture and / or solution is water.

17. The preparation method according to claim 16, characterized in that, The precursor of the active component is a compound containing the active component element, and the compound is a water-soluble compound.

18. The preparation method according to claim 17, characterized in that, The precursor of the active component is a compound containing the active component element, and the compound is a water-soluble salt.

19. The preparation method according to claim 10, characterized in that, The conditions for spray drying in step (4) include: a drying temperature of 250-350℃; and / or, The drying time is 0.1-2.0 h; and / or, The average diameter of the spray droplets is 20-200 μm.

20. The preparation method according to claim 19, characterized in that, The conditions for spray drying in step (4) include: a drying temperature of 300-350℃; and / or, The drying time is 0.2-1.0 h; and / or, The average diameter of the spray droplets is 40-180 μm.

21. The preparation method according to claim 10, characterized in that, The roasting conditions in step (5) include: roasting temperature of 250~700℃; roasting time of 30-300min.

22. The preparation method according to claim 21, characterized in that, The calcination conditions in step (5) include: heating to 250-400℃ at a calcination heating rate of 5-20℃ / min and holding for 10-60min; then further heating to 400-700℃ at a calcination heating rate of 5-20℃ / min and holding for 20-90min.

23. The use of a catalyst according to any one of claims 1 to 9 or a catalyst prepared by any one of claims 10 to 22 in the ammoxidation of propylene to acrylonitrile reaction.

24. The application according to claim 23, characterized in that, The reaction conditions include: a molar ratio of propylene / ammonia / air (based on O2) of 1:(1.1-1.35):(1.8-2.5), a reaction temperature of 420-440℃, a reaction pressure of 0.03-0.14 MPa (gauge pressure), and a weight hourly space velocity of 0.04-0.10 h⁻¹. -1 .

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