Ammonia oxidation catalyst, method for preparing and using the same, and method for preparing acrylonitrile

Abstract

The present application relates to the field of catalysts, in particular to an ammonia oxidation catalyst, a preparation method and application thereof, and a preparation method of acrylonitrile. The catalyst comprises a carrier and an active component, wherein the active component comprises a composite oxide of molybdenum, bismuth and iron, and the carrier comprises an inert oxide and an MFI molecular sieve. The inventors have found that, by optimizing the components of the catalyst and adding the MFI molecular sieve to the carrier, the adsorption and migration speed of raw material molecules on the surface of the catalyst can be enhanced, the adsorption activation rate can be improved, and thus the catalytic performance and stability of the catalyst under high load conditions can be improved.

Description

Technical Field

[0001] The present invention relates to the field of catalysts, and particularly relates to an ammonia oxidation catalyst, a preparation method and application thereof, and a preparation method of acrylonitrile. Background Art

[0002] As an important basic chemical raw material, acrylonitrile is currently commonly produced by a fluidized bed ammoxidation process. As one of the core technologies of this process, the research and improvement of catalysts have never stopped. Developing an acrylonitrile synthesis catalyst that can be used at a high catalyst load, that is, increasing the number of tons of propylene that can be processed per ton of catalyst per hour, is an important trend in the development of acrylonitrile catalysts at present. However, with the increase in catalyst load, the feed rate of the reactor increases, and the corresponding contact time between the catalyst and the raw materials will also be shortened, which puts higher requirements on the redox performance of the catalyst itself. Existing catalysts are prone to problems such as a rapid decrease in acrylonitrile yield and poor stability when used under high load conditions due to their own redox performance not being able to fully meet the requirements under high load conditions.

[0003] The raw materials for the propylene ammoxidation reaction include propylene, ammonia, and air. The catalyst needs to activate both propylene and ammonia simultaneously to achieve efficient reaction. Research shows that the Mo-Bi-based catalyst has a strong ability to activate ammonia and can effectively activate ammonia at a relatively low temperature (above 380°C). The main rate-determining step of the reaction is the adsorption activation of propylene. The adsorption activation rate of propylene molecules on the catalyst surface has an important impact on the activity of the catalyst and the selectivity of the reaction. A better catalyst should have a faster propylene adsorption and desorption rate and a moderate propylene adsorption strength to ensure the rapid desorption of products from the catalyst surface, thereby reducing the generation of by-products such as CO and CO2.

[0004] By controlling the spatial distribution of each element in the catalyst or adding appropriate support modifiers, the performance of the catalyst can be improved to a certain extent. For example, CN111744493A discloses an acrylonitrile catalyst. By controlling the relative magnitudes of the molar ratios of Mo / Bi elements on the surface of the catalyst particles and in the bulk phase, the stability of the catalyst during long-term operation can be improved, but the load used during catalyst evaluation is relatively low. CN107282063B, CN107282060B, and CN107282065B disclose adding a certain amount of zirconia, titania, and diatomaceous earth as support modifiers during the catalyst preparation process, which can improve the selectivity and stability of the catalyst in the propylene ammoxidation reaction, but their catalyst evaluations are also carried out under relatively low load conditions. Summary of the Invention

[0005] The object of the present invention is to overcome the problems existing in the prior art that the acrylonitrile yield of the propylene ammoxidation catalyst is low and the stability is poor under high load conditions, and to provide an ammoxidation catalyst, its preparation method and application, and a method for preparing acrylonitrile. This catalyst has the advantages of high activity and good stability under high load conditions.

[0006] To achieve the above object, the first aspect of the present invention provides an ammoxidation catalyst, which comprises a carrier and an active component. The active component contains a composite oxide of molybdenum, bismuth and iron, and the carrier contains an inert oxide and MFI zeolite.

[0007] The second aspect of the present invention provides a method for preparing an ammoxidation catalyst, which comprises:

[0008] (a) Dissolve the Mo precursor to obtain Solution I;

[0009] (b) Dissolve the Fe precursor, Bi precursor, optional precursor of element A, optional precursor of element B and optional precursor of element C, add carboxylic acid, and age to obtain Solution II;

[0010] (c) Mix the inert oxide precursor with MFI zeolite, perform the first-stage grinding and emulsification, and after completion, add Solution I and perform the second-stage grinding and emulsification to obtain Slurry I;

[0011] (d) Mix Slurry I with Solution II to obtain Slurry II;

[0012] (e) Boil, dry and calcine Slurry II;

[0013] Wherein, A is at least one of alkali metal elements, B is at least one of alkaline earth metal elements, transition metal elements, Group IIIA metal elements, antimony and tellurium; C is at least one of rare earth elements.

[0014] The third aspect of the present invention provides a catalyst prepared by the preparation method described in the second aspect of the present invention.

[0015] The fourth aspect of the present invention provides the application of the catalyst described in the first aspect of the present invention and the catalyst described in the third aspect in olefin ammoxidation.

[0016] The fifth aspect of the present invention provides a method for preparing acrylonitrile, which comprises: contacting and reacting acrylonitrile raw materials, an ammonia source and an oxygen source under catalyst conditions, wherein the catalyst is the catalyst described in the first aspect of the present invention and the catalyst described in the third aspect.

[0017] Through the above technical solutions, the present invention has the following advantages:

[0018] The inventors have found through research that by optimizing the composition of the catalyst and adding MFI zeolite to the carrier, the adsorption and migration rates of raw material molecules on the catalyst surface can be enhanced, the adsorption activation rate can be increased, and thus the catalytic performance and stability of the catalyst under high-load conditions can be improved.

[0019] In the catalyst preparation method of the present invention, the Mo component is promoted to be uniformly dispersed on the carrier by a segmented grinding and emulsification process, which can effectively increase the specific surface area of the catalyst while ensuring the uniform dispersion of the active components, and improve the catalytic performance and stability of the catalyst under high-load conditions.

[0020] The catalyst provided by the present invention is applied to olefin ammoxidation, especially in the reaction of propylene ammoxidation to acrylonitrile. It has high olefin ammoxidation activity and nitrile selectivity, and has a long service life under high-load conditions. It can maintain a high single-pass yield of acrylonitrile for a long time, thereby greatly improving the efficiency and economy of acrylonitrile production. The propylene conversion rate can reach more than 99%, and the single-pass yield of acrylonitrile can reach more than 84%. Detailed implementation mode

[0021] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0022] The present invention provides an ammoxidation catalyst, which includes a carrier and active components. The active components include a composite oxide of molybdenum, bismuth, and iron, and the carrier contains an inert oxide and MFI zeolite.

[0023] The inventors have found through research that by optimizing the composition of the catalyst and adding MFI zeolite to the carrier, the adsorption and migration rates of raw material molecules on the catalyst surface can be enhanced, the adsorption activation rate can be increased, and thus the catalytic performance and stability of the catalyst under high-load conditions can be improved.

[0024] The composite oxide is not just a simple composition of the respective oxides of metal elements, but also includes compounds formed by two or more metal elements. For example, the composite oxide of molybdenum, bismuth, and iron also contains iron molybdate, bismuth molybdate, iron bismuth molybdate, etc.

[0025] According to a preferred embodiment of the present invention, the MFI zeolite is at least one of Silicate-1 zeolite and ZSM-5 zeolite, preferably Silicate-1. By adopting the foregoing preferred scheme, the catalytic performance and stability of the catalyst under high load conditions can be further improved.

[0026] According to a preferred embodiment of the present invention, the average particle size of the MFI zeolite is 50 - 300 nm, preferably 50 - 150 nm. By adopting the foregoing preferred scheme, the catalytic performance and stability of the catalyst under high load conditions can be further improved.

[0027] According to a preferred embodiment of the present invention, the specific surface area of the MFI zeolite is 50 - 700 m 2 / g, preferably 300 - 700 m 2 / g. By adopting the foregoing preferred scheme, the catalytic performance and stability of the catalyst under high load conditions can be further improved.

[0028] In the present invention, the inert oxide refers to an oxide that cannot react with an acid or a base to form a salt and water of the corresponding valence state. According to a preferred embodiment of the present invention, the inert oxide is selected from at least one of silicon dioxide, zirconium dioxide, and titanium dioxide, preferably silicon dioxide.

[0029] In the present invention, the contents of the components of the carrier are not particularly limited. According to a preferred embodiment of the present invention, in the catalyst, based on the total mass of the carrier, the carrier includes: 5 - 50 wt% of MFI zeolite and 50 - 95 wt% of inert oxide.

[0030] According to a preferred embodiment of the present invention, in the catalyst, based on the total mass of the carrier, the carrier includes: 5 - 50 wt% of MFI zeolite and 50 - 95 wt% of inert oxide.

[0031] In the present invention, the contents of the components of the catalyst are not particularly limited. According to a preferred embodiment of the present invention, in the catalyst, based on the total mass of the catalyst, the catalyst includes: 30 - 70 wt% of carrier and 30 - 70 wt% of active component.

[0032] According to a preferred embodiment of the present invention, in the catalyst, based on the total mass of the catalyst, the catalyst includes: 40 - 60 wt% of carrier and 60 - 40 wt% of active component.

[0033] According to a preferred embodiment of the present invention, the general formula of the active component is Fe d Bi e Mo f Aa B b C c O x , wherein, A is at least one of alkali metal elements, B is at least one of alkaline earth metal elements, transition metal elements, Group IIIA metal elements, antimony and tellurium; C is at least one of rare earth elements, the value range of a is 0 - 3, preferably 0.05 - 2.5; the value range of b is 0 - 15, preferably 1 - 10; the value range of c is 0 - 4, preferably 0.01 - 3; the value range of d is 0.1 - 6, preferably 0.5 - 3; the value range of e is 0.01 - 3, preferably 0.01 - 1.5; the value range of f is 9 - 16, preferably 10 - 15; x is the total number of oxygen atoms required to satisfy the valence of each element in the above active components. By adopting the foregoing preferred scheme, the catalytic performance and stability of the catalyst under high load conditions can be further improved.

[0034] According to a preferred embodiment of the present invention, the alkali metal element is selected from at least one of Li, Na, K, Rb and Cs.

[0035] According to a preferred embodiment of the present invention, the alkaline earth metal element is selected from at least one of Mg, Ca, Ba and Sr.

[0036] According to a preferred embodiment of the present invention, the transition metal element is selected from at least one of Mn, Co, Ni, Zn, Cr, Zr, Ti, Nb and W, preferably Ni and Co, and more preferably the molar ratio of Ni and Co is 3 - 10.

[0037] According to a preferred embodiment of the present invention, the Group IIIA metal element is selected from at least one of Al, Ga and In.

[0038] According to a preferred embodiment of the present invention, the active component Fe d Bi e Mo f A a B b C c O x in, e / f is 0.005 - 0.40, preferably 0.01 - 0.20; d / f is 0.02 - 1.50, preferably 0.1 - 1.0. By adopting the foregoing preferred scheme, the catalytic performance and stability of the catalyst under high load conditions can be further improved.

[0039] The present invention provides a preparation method of an ammonia oxidation catalyst, and the method includes:

[0040] (a) Dissolve the Mo precursor to obtain Solution I;

[0041] (b) Dissolve the Fe precursor, Bi precursor, optional precursor of element A, optional precursor of element B, and optional precursor of element C, add carboxylic acid, and age to obtain Solution II;

[0042] (c) Mix the inert oxide precursor with the MFI zeolite, carry out the first-stage grinding and emulsification, and after completion, add Solution I and carry out the second-stage grinding and emulsification to obtain Slurry I;

[0043] (d) Mix Slurry I with Solution II to obtain Slurry II;

[0044] (e) Boil Slurry II, dry, and calcine;

[0045] In the method, the preparation sequence of Slurry I and Solution II has no priority. Among them, A is at least one of the alkali metal elements, B is at least one of the alkaline earth metal elements, transition metal elements, Group IIIA metal elements, antimony, and tellurium; C is at least one of the rare earth elements.

[0046] In the catalyst preparation method of the present invention, the process of grinding and emulsification is carried out in stages to promote the uniform dispersion of the Mo component on the carrier, which can effectively improve the specific surface area of the catalyst while ensuring the uniform dispersion of the active components. Improve the catalytic performance and stability of the catalyst under high-load conditions.

[0047] According to a preferred embodiment of the present invention, the conditions for the grinding and emulsification include: carrying out grinding in a device capable of realizing grinding and emulsification, such as a colloid mill.

[0048] According to a preferred embodiment of the present invention, the conditions for the first-stage grinding and emulsification include: a rotation speed of 500 - 1500 revolutions per minute and a time of 0.25 - 0.5 h.

[0049] According to a preferred embodiment of the present invention, the conditions for the second-stage grinding and emulsification include: a rotation speed of 1000 - 2000 revolutions per minute and a time of 0.5 - 1 h.

[0050] According to a preferred embodiment of the present invention, the conditions for the aging include: a temperature of 40 - 80 °C, a time of 0.1 - 0.5 h, and a stirring speed of 200 - 1000 rpm; the aging time is adjusted according to the temperature and stirring speed.

[0051] According to a preferred embodiment of the present invention, in step (b), the molar ratio of the addition amount of the carboxylic acid to the total molar amount of elements B and C is (0.01 - 0.50)∶1.

[0052] According to a preferred embodiment of the present invention, the conditions for the boiling include: a temperature of 80 - 175 °C, a time of 0.1 - 3 h, and a stirring speed of 200 - 1000 rpm.

[0053] According to a preferred embodiment of the present invention, the drying method is spray drying, and the conditions for spray drying include: the drying temperature is 250-400 °C, the drying time is 0.5-3 h, and the average diameter of the spray droplets is 40-200 μm.

[0054] According to a preferred embodiment of the present invention, the conditions for roasting include: under an oxygen-containing atmosphere, the roasting temperature is 200-750 °C, and the roasting time is 2-8 h.

[0055] According to a preferred embodiment of the present invention, the carboxylic acid is a polycarboxylic acid, preferably at least one of oxalic acid, citric acid, tartaric acid, and ethylenediaminetetraacetic acid.

[0056] According to a preferred embodiment of the present invention, the inert oxide precursor is at least one of silica sol, water glass, inorganic silica gel, and silicate ester, preferably silica sol, and more preferably the solid content of the silica sol is 20-50 wt% based on silicon dioxide, and the average particle size is 5-50 nm.

[0057] According to a preferred embodiment of the present invention, the MFI zeolite is at least one of Silicate-1 zeolite and / or ZSM-5 zeolite, preferably Silicate-1 zeolite.

[0058] According to a preferred embodiment of the present invention, the average particle size of the MFI zeolite is 50-300 nm, preferably 50-150 nm.

[0059] According to a preferred embodiment of the present invention, the specific surface area of the MFI zeolite is 50-700 m 2 / g, preferably 300-700 m 2 / g.

[0060] In the present invention, the precursor of each element is a soluble compound of the corresponding element.

[0061] The present invention provides a catalyst prepared by the preparation method described in the present invention.

[0062] The present invention provides an application of the catalyst described in the present invention in the ammoxidation of olefins, preferably in the ammoxidation of propylene to prepare acrylonitrile.

[0063] The present invention provides a method for preparing acrylonitrile, which includes: contacting and reacting an acrylonitrile raw material, an ammonia source, and an oxygen source under the condition of a catalyst; wherein, the catalyst is the catalyst described in the present invention.

[0064] According to a preferred embodiment of the present invention, the conditions for the contact reaction include: the molar ratio of propylene raw material based on propylene: ammonia source based on ammonia: oxygen source based on oxygen is 1:1.0 - 1.5:1.65 - 2.25, preferably 1:1 - 1.3:1.85 - 2.10.

[0065] According to a preferred embodiment of the present invention, the conditions for the contact reaction include: the reaction temperature is 400 - 470 °C, preferably 410 - 450 °C.

[0066] According to a preferred embodiment of the present invention, the conditions for the contact reaction include: the reaction pressure is 0.03 - 0.15 MPa, preferably 0.06 - 0.14 MPa.

[0067] According to a preferred embodiment of the present invention, the conditions for the contact reaction include: the reaction load WWH is 0.045 - 0.15 h -1 preferably 0.06 - 0.12 h -1 .

[0068] The present invention will be described in detail below through examples.

[0069] In the following examples:

[0070] The activity evaluation of the catalyst was carried out in a fluidized bed reactor with an inner diameter of 38 mm. The catalyst loading was 400 g, at a reaction temperature of 430 °C, a molar ratio of raw material propylene: ammonia: oxygen (air feed) of 1:1.25:2.04, a reaction pressure (gauge pressure) of 0.085 MPa, and a reaction load (WWH) of 0.095 h -1 .

[0071] The conversion rate of propylene, the selectivity of acrylonitrile, and the single - pass yield are used as the evaluation indexes for the catalyst performance, and their definitions are as follows:

[0072] Propylene conversion rate (%) = (moles of propylene consumed in the reaction / moles of propylene fed) × 1 hundred%;

[0073] Acrylonitrile selectivity (%) = (moles of acrylonitrile produced / moles of propylene consumed in the reaction) × 1 hundred%;

[0074] Acrylonitrile single - pass yield (%) = (moles of acrylonitrile produced / moles of propylene fed) × 1 hundred%.

[0075] The raw materials are all commercially available products.

[0076] Example 1

[0077] Put 754.2 g of (NH4)6Mo7O 24·4H2O was dissolved in 500 mL of water to obtain a mixed solution I. 228.6 g of Bi(NO3)3·5H2O, 456.8 g of Ni(NO3)2·6H2O, 137.1 g of Co(NO3)2·6H2O, 380.7 g of Fe(NO3)3·9H2O, 80.5 g of Mg(NO3)2·6H2O, 4.4 g of KOH, and 82.0 g of Pr(NO3)3·6H2O were dissolved in 100 mL of water, and 31.8 g of oxalic acid was added. The molar ratio of the added amount of oxalic acid to the total molar amount of element B (Ni, Co, Mg) and element C (Pr) was 0.14:1. It was aged at 60 °C with a stirring speed of 400 rpm for 0.25 h to obtain a mixed solution II. Then, first, 1500 g of silica sol with a weight concentration of 40 wt%, 1000 g of water, and 400 g of Silicate-1 molecular sieve with an average particle size of 150 nm and a specific surface area of 400 m 2 / g were mixed. The slurry was transferred to a colloid mill for the first-stage grinding and emulsification, and was ground at 750 revolutions per minute for 0.25 h. Then, solution I was added for the second-stage grinding and emulsification, and was ground at 1000 revolutions per minute for 0.5 h to obtain slurry I. Then, slurry I and the mixed solution II were mixed and stirred and boiled at a temperature of 100 °C with a stirring speed of 300 rpm for 1.5 h. Then, spray drying was carried out at a drying temperature of 325 °C and a drying time of 1 h, and the average diameter of the spray droplets was 120 μm to obtain particulate matter. Finally, the obtained particulate matter was calcined in an oxygen-containing atmosphere (oxygen volume fraction 21%) at 580 °C for 3 h to obtain a catalyst.

[0078] The composition of the catalyst obtained according to the above steps is represented by the following formula:

[0079] 50 wt% K 0.25 Co 1.5 Ni 5.0 Mg 1.0 Pr 0.6 Fe 3.0 Bi 1.5 Mo 13.6 O x +30 wt% SiO2 + 20 wt% Silicate-1[[ID=QQ27]]

[0080] The activity evaluation of the catalyst showed that the propylene conversion rate of the catalyst was 98.6%, the acrylonitrile selectivity was 84.仁%, and the single-pass acrylonitrile yield was 82.9%.

[0081] Example 2

[0082] The catalyst preparation steps were the same as those in Example 1, except that

[0083] The raw material was 759.0 g of (NH4)6Mo7O24 ·4H2O, 230.0 g of Bi(NO3)3·5H2O, 551.5 g of Ni(NO3)2·6H2O, 112.0 g of Ca(NO3)2·4H2O, 113.1 g of a 50 wt% Mn(NO3)2 solution, 225.4 g of Fe(NO3)3·9H2O, 4.4 g of KOH, 55.0 g of Pr(NO3)3·6H2O;

[0084] Change the molar ratio of the addition amount of oxalic acid to the total molar amount of B element (Ni, Mn, Ca) and C element (Pr) to 0.25∶1;

[0085] Add 2000 g of a 40 wt% silica sol, 500 g of water and 200 g of Silicate-1 molecular sieve;

[0086] The average particle size of the Silicate-1 molecular sieve is 100 nm and the specific surface area is 475 m 2 / g;

[0087] Perform the first-stage grinding and emulsification, grind for 0.5 h under the condition of 750 rpm, and perform the second-stage grinding and emulsification, grind for 0.5 h under the condition of 1500 rpm;

[0088] The composition of the catalyst is represented by the following formula:

[0089] 50 wt% K 0.25 Mn 1.0 Ni 6.0 Ca 1.5 Pr 0.4 Fe 2.0 Bi 1.5 Mo 13.6 O x +40 wt% SiO2 + 10 wt% Silicate-1

[0090] The activity evaluation of the catalyst shows that the propylene conversion rate of the catalyst is 98.2%, the acrylonitrile selectivity is 84.3%, and the acrylonitrile single-pass yield is 82.8%.

[0091] Example 3

[0092] The catalyst preparation steps are the same as those in Example 1, except that

[0093] The raw material is 941.0 g of (NH4)6Mo7O 24· 4H2O, 285.1 g of Bi(NO3)3·5H2O, 455.9 g of Ni(NO3)2·6H2O, 114.1 g of Co(NO3)2·6H2O, 395.8 g of Fe(NO3)3·9H2O, 201.0 g of Mg(NO3)2·6H2O, 11.6 g of RbNO3, 82.2 g of Pr(NO3)3·6H2O;

[0094] Add 2000 g of silica sol with a weight concentration of 30 wt%, 475 g of water and 200 g of Silicate-1 molecular sieve; the inert oxide precursor is silica sol with a weight concentration of 30 wt%.

[0095] The first-stage grinding and emulsification is carried out by grinding for 0.25 h at 1250 rpm, and the second-stage grinding and emulsification is carried out by grinding for 0.75 h at 1750 rpm;

[0096] 60 wt% Rb 0.20 Co 1.0 Ni 4.0 Mg 2.0 Pr 0.5 Fe 2.5 Bi 1.5 Mo 13.6 O x + 30 wt% SiO2 + 10 wt% Silicate-1;

[0097] The activity evaluation of the catalyst shows that the propylene conversion rate of the catalyst is 99.1%, the acrylonitrile selectivity is 83.2%, and the single-pass yield of acrylonitrile is 82.5%.

[0098] Example 4

[0099] The catalyst preparation steps are the same as those in Example 1, except that

[0100] The added MFI zeolite ZSM-5 zeolite has an average particle size of 150 nm and a specific surface area of 416 m 2 / g;

[0101] The composition of the catalyst is represented by the following formula:

[0102] 50% K 0.25 Co 1.5 Ni 5.0 Mg 1.0 Pr 0.6 Fe 3.0 Bi<0000​​​​​​​The activity evaluation of the catalyst shows that the propylene conversion rate of the catalyst is 98.0%, the acrylonitrile selectivity is 82.6%, and the single-pass yield of acrylonitrile is 80.9%.

[0104] Example 5

[0105] The catalyst preparation steps are the same as those in Example 1, except that

[0106] the average particle size of Silicate-1 molecular sieve is 1000 nm and the specific surface area is 250 m 2 / g;

[0107] The composition of the catalyst is represented by the following formula:

[0108] 50% K 0.25 Co 1.5 Ni 5.0 Mg 1.0 Pr 0.6 Fe 3.0 Bi 1.5 Mo 13.6 O x +30% SiO2 + 20% Silicate-1

[0109] The activity evaluation of the catalyst shows that the propylene conversion rate of the catalyst is 98.5%, the acrylonitrile selectivity is 82.8%, and the single-pass yield of acrylonitrile is 81.6%.

[0110] Example 6

[0111] The catalyst preparation steps are the same as those in Example 1, except that

[0112] the raw materials are (NH4)6Mo7O 24 ·4H2O, Bi(NO3)3·5H2O, Ni(NO3)2·6H2O, Ca(NO3)2·4H2O, Fe(NO3)3·9H2O, Mg(NO3)2·6H2O, KOH, Pr(NO3)3·6H2O;

[0113] Control the amount of raw materials added so that the composition of the prepared catalyst is as follows:

[0114] 50 wt% K 0.25 Ca 1.5 Ni 5.0 Mg 1.0 Pr 0.6 Fe 3.0 Bi 1.5 Mo 13.6 O x +30 wt% SiO2 + 20 wt% Silicate-1

[0115] The activity evaluation of the catalyst shows that the propylene conversion rate of the catalyst is 98.8%, the acrylonitrile selectivity is 83.5%, and the single-pass acrylonitrile yield is 82.5%.

[0116] Example 7

[0117] The catalyst preparation steps are the same as those in Example 1, except that

[0118] the carboxylic acid added is citric acid, and the molar ratio of the added amount of citric acid to the total molar amount of B element and C element is 0.14∶1;

[0119] The composition of the catalyst obtained according to the above steps is represented by the following formula:

[0120] 50wt% K 0.25 Co 1.5 Ni 5.0 Mg 1.0 Pr 0.6 Fe 3.0 Bi 1.5 Mo 13.6 O x +30wt% SiO2 + 20wt% Silicate-1

[0121] The activity evaluation of the catalyst shows that the propylene conversion rate of the catalyst is 98.0%, the acrylonitrile selectivity is 83.5%, and the single-pass acrylonitrile yield is 81.8%.

[0122] Example 8

[0123] The catalyst preparation steps are the same as those in Example 1, except that

[0124] The spray drying conditions are a drying temperature of 240°C, a drying time of 1 h, and an average spray droplet diameter of 120 μm.

[0125] The composition of the catalyst obtained according to the above steps is represented by the following formula:

[0126] 50wt% K 0.25 Co 1.5 Ni 5.0 [[ID=​​​​​​​​​​​​​​​​​​​

[0129] The catalyst preparation steps are the same as in Example 1, except that

[0130] The calcination conditions are as follows: calcination is carried out in an oxygen-containing atmosphere (oxygen volume fraction 21%) at 800 °C for 3 h.

[0131] The composition of the catalyst obtained according to the above steps is represented by the following formula:

[0132] 50 wt% K 0.25 Co 1.5 Ni 5.0 Mg 1.0 Pr 0.6 Fe 3.0 Bi 1.5 Mo 13.6 O x + 30 wt% SiO2 + 20 wt% Silicate-1

[0133] The activity evaluation of the catalyst shows that the propylene conversion rate of the catalyst is 98.1%, the acrylonitrile selectivity is 83.0%, and the single-pass acrylonitrile yield is 81.4%.

[0134] Comparative Example 1

[0135] The catalyst preparation steps are the same as in Example 1, except that

[0136] MFI zeolite is not added, and only silica sol with a weight concentration of 40 wt% is used as the carrier precursor.

[0137] The composition of the catalyst obtained according to the above steps is represented by the following formula:

[0138] 50 wt% K 0.25 Co 1.5 Ni 5.0 Mg 1.0 Pr 0.6 Fe 3.0 Bi 1.5 Mo 13.6 O x + 50 wt% SiO2;

[0139] The activity evaluation of the catalyst shows that the propylene conversion rate of the catalyst is 97.3%, the acrylonitrile selectivity is 82.5%, and the single-pass acrylonitrile yield is 80.3%.

[0140] Comparative Example 2

[0141] The catalyst preparation steps are the same as in Example 1, except that

[0142] Silica sol with a weight concentration of 40 wt% is not added, and only MFI zeolite Silicate-1 zeolite is used as the carrier.

[0143] The composition of the catalyst obtained according to the above steps is represented by the following formula:

[0144] 50 wt% K 0.25 Co 1.5 Ni 5.0 Mg 1.0 Pr 0.6 Fe 3.0 Bi 1.5 Mo 13.6 O x + 50 wt% Silicate-1;

[0145] The activity evaluation of the catalyst shows that the propylene conversion rate of the catalyst is 97.3%, the acrylonitrile selectivity is 81.8%, and the single-pass acrylonitrile yield is 79.6%.

[0146] Comparative Example 3

[0147] The catalyst preparation steps are the same as those in Example 1, except that

[0148] the molecular sieve added is Beta molecular sieve;

[0149] The composition of the catalyst obtained according to the above steps is represented by the following formula:

[0150] 50 wt% K 0.25 Co 1.5 Ni 5.0 Mg 1.0 Pr 0.6 Fe 3.0 Bi 1.5 Mo 13.6 O x + 30 wt% SiO2 + 20 wt% Beta

[0151] The activity evaluation of the catalyst shows that the propylene conversion rate of the catalyst is 97.0%, the acrylonitrile selectivity is 81.5%, and the single-pass acrylonitrile yield is 79.0%.

[0152] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the technical concept scope of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. An ammonia oxidation catalyst, characterized in that, The catalyst comprises a support and an active component, wherein the active component contains a composite oxide of molybdenum, bismuth, and iron, and the support contains an inert oxide and a Silicate-1 molecular sieve. In this catalyst, based on the total mass of the support, the support includes: 5-50 wt% Silicate-1 molecular sieve and 50-95 wt% inert oxides; The Silicate-1 molecular sieve has an average particle size of 50-150 nm and a specific surface area of ​​300-700 m². 2 / g.

2. The catalyst according to claim 1, wherein, The inert oxide is selected from at least one of silicon dioxide, zirconium dioxide, and titanium dioxide.

3. The catalyst according to claim 2, wherein, The inert oxide is silicon dioxide.

4. The catalyst according to claim 1, wherein, The catalyst, based on its total mass, comprises: 30-70 wt% support and 30-70 wt% active component.

5. The catalyst according to claim 4, wherein, The catalyst, based on its total mass, comprises: 40-60 wt% support and 60-40 wt% active component.

6. The catalyst according to claim 1, wherein, The general formula of the active component is Fe d Bi e Mo f A a B b C c O x Wherein, A is at least one of the alkali metal elements, B is at least one of the alkaline earth metal elements, transition metal elements, Group IIIA metal elements, antimony and tellurium; C is at least one of the rare earth elements, the value of a ranges from 0 to 3; the value of b ranges from 0 to 15; the value of c ranges from 0 to 4; the value of d ranges from 0.1 to 6; the value of e ranges from 0.01 to 3; the value of f ranges from 9 to 16; and x is the total number of oxygen atoms required to satisfy the oxidation states of each element in the above active components.

7. The catalyst according to claim 6, wherein, The general formula of the active component is Fe d Bi e Mo f A a B b C c O x The values ​​of a range from 0.05 to 2.5; the values ​​of b range from 1 to 10; the values ​​of c range from 0.01 to 3; the values ​​of d range from 0.5 to 3; the values ​​of e range from 0.01 to 1.5; and the values ​​of f range from 10 to 15.

8. The catalyst according to claim 6, wherein, 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 Mg, Ca, Ba, and Sr; and / or The transition metal element is selected from at least one of Mn, Co, Ni, Zn, Cr, Zr, Ti, Nb, and W; and / or Group IIIA metals are selected from at least one of Al, Ga, and In.

9. The catalyst according to claim 8, wherein, The transition metal elements are Ni and Co.

10. The catalyst according to claim 7, wherein, The active component Fe d Bi e Mo f A a B b C c In this context, e / f ranges from 0.005 to 0.40; d / f ranges from 0.02 to 1.

50.

11. The catalyst according to claim 10, wherein, The active component Fe d Bi e Mo f A a B b C c In this context, e / f is 0.01-0.20; d / f is 0.1-1.

0.

12. A method for preparing an ammonia oxidation catalyst, characterized in that, The method includes: (a) Dissolve the Mo precursor to obtain solution I; (b) Dissolve the Fe precursor, Bi precursor, optional A element precursor, optional B element precursor and optional C element precursor, add carboxylic acid, age, and obtain solution II. (c) The inert oxide precursor is mixed with Silicate-1 molecular sieve and subjected to the first stage of grinding and emulsification. After the first stage is completed, solution I is added and subjected to the second stage of grinding and emulsification to obtain slurry I. (d) Mix slurry I with solution II to obtain slurry II; (e) Boil slurry II, dry it, and calcine it; Wherein, A is at least one of the alkali metal elements; B is at least one of the alkaline earth metal elements, transition metal elements, Group IIIA metal elements, antimony, and tellurium; C is at least one of the rare earth elements; based on the total amount of inert oxide and Silicate-1 molecular sieve, it includes: 5-50 wt% Silicate-1 molecular sieve and 50-95 wt% inert oxide; the average particle size of the Silicate-1 molecular sieve is 50-150 nm; the specific surface area of ​​the Silicate-1 molecular sieve is 300-700 m². 2 / g.

13. The preparation method according to claim 12, wherein, The conditions for the first stage of polishing and emulsification include: a rotation speed of 500-1500 rpm and a time of 0.25-0.5 h; and / or The conditions for the second stage of polishing and emulsification include: a rotation speed of 1000-2000 rpm and a time of 0.5-1 hour; and / or The aging conditions include: a temperature of 40-80℃, a time of 0.1-0.5h, and a stirring speed of 200-1000rpm; and / or In step (b), the molar ratio of the amount of carboxylic acid added to the total moles of elements B and C is (0.01~0.50):1; The conditions for boiling the slurry include: a temperature of 80-175℃, a time of 0.1-3 hours, and a stirring speed of 200-1000 rpm; and / or The drying method is spray drying, and the spray drying conditions include: a drying temperature of 250-400℃, a drying time of 0.5-3 hours, and an average droplet diameter of 40-200 μm; and / or The calcination conditions include: calcination temperature of 200-750℃ and calcination time of 2-8h under an oxygen-containing atmosphere.

14. The preparation method according to claim 12, wherein, The carboxylic acid is a polycarboxylic acid; and / or The inert oxide precursor is at least one of silica sol, water glass, inorganic silica gel, and silicate ester.

15. The preparation method according to claim 14, wherein, The carboxylic acid is at least one selected from oxalic acid, citric acid, tartaric acid, and ethylenediaminetetraacetic acid; and / or The inert oxide precursor is silica sol.

16. The preparation method according to claim 14, wherein, The solid content of the silica sol is 20-50 wt% based on silicon dioxide, and the average particle size is 5-50 nm.

17. The catalyst prepared by the preparation method according to any one of claims 12-16.

18. The use of the catalyst according to any one of claims 1-11 and the catalyst according to claim 17 in the ammoxidation of olefins.

19. The application according to claim 18 is specifically its application in the ammoxidation of propylene to prepare acrylonitrile.

20. A method for preparing acrylonitrile, characterized in that, This method includes: reacting acrylonitrile feedstock, ammonia source, and oxygen source under catalytic conditions; The catalyst is the catalyst described in any one of claims 1-11 and the catalyst described in claim 17.

21. The method for preparing acrylonitrile according to claim 20, wherein, The conditions for the contact reaction include: The molar ratio of propylene feedstock (based on propylene), ammonia source (based on ammonia), and oxygen source (based on oxygen) is 1:1.0-1.5:8-10.5; and / or The reaction temperature is 400-470℃; and / or The reaction pressure is 0.03-0.15 MPa; and / or The reaction loading (WWH) is 0.045-0.15 h. -1 .

22. The method for preparing acrylonitrile according to claim 20, wherein, The conditions for the contact reaction include: The molar ratio of propylene feedstock (based on propylene), ammonia source (based on ammonia), and oxygen source (based on oxygen) is 1:1-1.3:8.8-10; and / or The reaction temperature is 410-450℃; and / or The reaction pressure is 0.06-0.14 MPa; and / or The reaction loading (WWH) is 0.06-0.12 h. -1 .