Catalyst for synthesizing acrylonitrile as well as preparation method and application of catalyst

Abstract

The invention provides a catalyst for synthesizing acrylonitrile as well as a preparation method and application of the catalyst. The preparation method comprises the following steps: uniformly mixing a metal salt solution, alkaline silica sol and SAPO34 molecular sieve slurry to obtain precursor slurry; and granulating, drying and roasting the precursor slurry to obtain the catalyst for synthesizing acrylonitrile, wherein the general formula of the metal salt solution is Mo < 30 > Bi N < c > Fe < d > Mg < e > B < f > C < g > in terms of metal elements, B comprises one or more of aluminum, lithium, sodium and potassium, and C comprises one or more of lanthanum, cerium, praseodymium, scandium and yttrium. According to the preparation method, a molecular sieve catalyst and a traditional inorganic salt catalyst are well combined, and the prepared catalyst is high in catalytic activity, high in acrylonitrile selectivity, few in side reaction and beneficial to being popularized and applied to a large-scale propylene ammoxidation fluidized bed reactor.

Description

Technical Field

[0001] The invention relates to the technical field of catalyst preparation, and in particular to a catalyst for synthesizing acrylonitrile and a preparation method and application thereof. Background Art

[0002] The chemical formula of acrylonitrile is C3H3N. It is a core chemical raw material and a key polymerization monomer. Its application fields are wide and in-depth, mainly including but not limited to the production of synthetic fibers (such as acrylic fibers), and the manufacture of various polymer materials, such as acrylonitrile-butadiene-styrene copolymer (ABS), styrene-acrylonitrile copolymer (SAN) and other engineering plastics, as well as the preparation of special rubbers such as nitrile rubber; in addition, acrylonitrile is also a key raw material for the production of high-end materials such as polyacrylamide, a surfactant for oil recovery, and polyacrylonitrile fiber, a precursor of carbon fiber.

[0003] In recent years, with the acceleration of the global industrialization process and the surge in demand for high-performance materials in emerging industries, the market demand for acrylonitrile has shown an upward trend year by year, further promoting the continuous innovation and optimization of large-scale acrylonitrile production technology. At present, the main production methods of acrylonitrile include propylene ammoxidation, propane ammoxidation and biomass conversion. Among them, the propylene ammoxidation method uses a fluidized bed reactor. The advantages are easy access to raw materials, simple process, low cost and stable product quality. By-products include hydrocyanic acid, acetonitrile and ammonium sulfate. The technical key to this process lies in the catalyst. Especially in industrial production, the activity and durability of the catalyst are key considerations. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention discloses a catalyst for synthesizing acrylonitrile and a preparation method and application thereof. The catalyst for synthesizing acrylonitrile prepared by the preparation method has high catalytic activity, high acrylonitrile selectivity and few side reactions, and is conducive to promotion and application in a large-scale propylene ammoxidation process fluidized bed reactor.

[0005] In order to achieve the above technical objectives, on the one hand, the present invention provides a method for preparing a catalyst for synthesizing acrylonitrile, the method comprising uniformly mixing a metal salt solution, an alkaline silica sol and a SAPO34 molecular sieve slurry to obtain a precursor slurry; granulating, drying and calcining the precursor slurry to obtain the catalyst for synthesizing acrylonitrile; wherein the general formula of the metal element in the metal salt solution is Mo 30 Bi b Ni c Fe d Mg e B f C g , wherein B includes one or more of aluminum, lithium, sodium, and potassium, and C includes one or more of lanthanum, cerium, praseodymium, scandium, and yttrium.

[0006] The active components of the catalyst prepared in the above technical scheme include oxides of component A (Mo, Bi, Ni, Fe and Mg), oxides of component B elements and oxides of component C elements. The three groups of active components are coordinated to catalyze the reaction of preparing acrylonitrile with propylene, ammonia and air as raw materials, and the catalytic activity is high. In the preparation process of the catalyst for synthesizing acrylonitrile of the present invention, SAPO34 molecular sieve is introduced, and the molecular sieve catalyst and the traditional inorganic salt catalyst are well combined, which can not only increase the number of acid sites of the catalyst, but also adsorb and screen small molecular raw materials and products in the reaction of catalytic synthesis of acrylonitrile. In addition, the introduction of SAPO34 molecular sieve increases the specific surface area of ​​the catalyst, thereby achieving the technical effect of improving the overall activity of the catalyst and the selectivity of acrylonitrile.

[0007] In addition, the preparation method of the above-mentioned catalyst adds SAPO34 molecular sieve in the form of slurry to the metal salt solution of specific components, mixes evenly to obtain precursor slurry, and then directly forms dry particles by spray drying. The operation process is simple and easy to implement, environmentally friendly and of great industrial value; the catalyst dry particles are activated by calcination, which can not only prevent the catalyst from sticking again during the activation process, but also achieve the effect of removing fine powder and exhaust gas.

[0008] It should be noted that the metal salt solution of the present invention is obtained by dissolving a metal soluble salt in water. The present invention does not limit the preparation process of the metal salt solution, and a salt solution of molybdenum and other metal salt solutions other than molybdenum can be prepared separately, and then the salt solution of molybdenum and other metal salt solutions other than molybdenum are mixed to obtain the metal salt solution. The present invention is not limited to the type of specific metal salt. Optionally, the salt solution of molybdenum can be obtained by dissolving molybdic acid, potassium molybdate, sodium molybdate or ammonium molybdate in water; further, it can be an aqueous solution of ammonium molybdate; further, the present invention does not limit the type of salts of other metal elements, and can be selected as soluble salts, such as nitrates, chlorides, sulfates, etc., and can be further selected as nitrates of other metal elements. Those skilled in the art can set it according to actual conditions.

[0009] In order to promote the dissolution of metal salts in water, in the specific preparation process, water above about 75° C. can be used to dissolve the metal salts, assisted by stirring, ultrasound or other operations that can promote the solution; if the dissolution is incomplete, an appropriate amount of nitric acid can be added to reduce the pH value of the solution to about 0.3 to promote complete dissolution.

[0010] In the actual operation process, the metal salt solution and silica sol are mixed in a suspension state, and after the SAPO34 molecular sieve slurry is injected, stirring operation can be performed, and a certain temperature is maintained to facilitate the uniform diffusion of salt, silica sol and molecular sieve. In order to promote the uniform mixing of salt, silica sol and molecular sieve, a beating operation can be performed to obtain the precursor slurry with uniform dispersion of each component.

[0011] Optionally, the precursor slurry is a homogeneous slurry with a solid content of 25%-45%.

[0012] In a further example of the present invention, the addition amount and performance parameters of the SAPO34 molecular sieve are optimized.

[0013] Optionally, the amount of SAPO34 molecular sieve added to the SAPO34 molecular sieve slurry is 0.5%-1.5% of the catalyst mass. The amount of SAPO34 molecular sieve added is relatively small, which is beneficial to promote the mixing of metal salt solution, alkaline silica sol and SAPO34 molecular sieve slurry during the preparation process, and does not affect the molding process of the overall catalyst.

[0014] Optionally, the silicon-aluminum ratio of the SAPO34 molecular sieve is 0.2-0.32, preferably 0.2; the phosphorus-aluminum ratio is 0.6-1, preferably 0.8. Optimizing the silicon-aluminum ratio and phosphorus-aluminum ratio of the SAPO34 molecular sieve is beneficial to improving the selectivity of the prepared catalyst and reducing the selectivity of CO and CO2.

[0015] Optionally, the particle size of the SAPO34 molecular sieve in the SAPO34 molecular sieve slurry is 0.3-2 μm. The particle size of the SAPO34 molecular sieve added in the present invention is much smaller than the particle size of the catalyst after molding, which is beneficial to the granulation and drying of the catalyst.

[0016] In a further example of the present invention, the preparation process of the SAPO34 molecular sieve slurry was explored and optimized.

[0017] Optionally, the SAPO34 molecular sieve slurry preparation process includes: preparing an initial glue solution containing an aluminum source, a silicon source, a phosphorus source, a template and water; the initial glue solution is crystallized and washed to obtain the SAPO34 molecular sieve slurry; wherein the template agent is one or more of triethylamine, diethylamine and n-butylamine; the molar ratio of the template agent to Al2O3 in the SAPO34 molecular sieve is 1.2-1.8. The method is used to obtain a slurry of a SAPO34 molecular sieve with weak acidity, further increasing the catalytic activity of the catalyst for synthesizing acrylonitrile prepared by the present invention, so that carbon deposition is not easy to occur during the reaction process of catalyzing the synthesis of acrylonitrile, and hydrocarbon side reactions are not easy to occur, thereby improving the selectivity of acrylonitrile.

[0018] In the process of preparing the SAPO34 molecular sieve slurry, it is also optional to evaporate the free liquid template in situ from the material after the crystallization is completed, so as to increase the specific surface area of ​​the prepared SAPO34 molecular sieve.

[0019] The washing operation may be performed by washing the crystallized material with deionized water until it becomes neutral; the washing operation may be performed once or in multiple times, such as washing the crystallized material with deionized water 3-4 times.

[0020] In the process of preparing the SAPO34 molecular sieve slurry, the washed SAPO34 molecular sieve raw powder slurry can also be slurried to obtain a suspension-like SAPO34 molecular sieve slurry, which is convenient for fully mixing with a metal salt solution and alkaline silica sol to obtain the precursor slurry.

[0021] Optionally, the solid content of the SAPO34 molecular sieve slurry is 25%-40%.

[0022] Optionally, the silicon source includes one or more of sodium silicate, tetraethyl orthosilicate, methyl orthosilicate, propyl orthosilicate, and silica sol; further optionally, the silicon source includes silica sol and tetraethyl orthosilicate; further optionally, the mass ratio of the silica sol to tetraethyl orthosilicate is 1:1-1:3. Optionally, the aluminum source includes one or more of aluminum sulfate, aluminum nitrate, pseudo-boehmite, dry glue, aluminum trioxide, aluminum isopropoxide, aluminum hydroxide, and activated alumina, and further optionally one or more of pseudo-boehmite, aluminum sulfate, and aluminum nitrate, and further optionally one or more of pseudo-boehmite. Optionally, the phosphorus source includes one or more of phosphoric acid, phosphorous acid, hypophosphorous acid, ammonium phosphate, monoammonium phosphate, and diammonium phosphate, and further optionally phosphoric acid. The silicon source, aluminum source, and phosphorus source used to prepare the SAPO34 molecular sieve in the present invention are widely available, and the preparation method of the catalyst for synthesizing acrylonitrile has strong universality.

[0023] In a further example of the present invention, optionally, in the general formula, b is in the range of 0.8-2.2, c is in the range of 7-15, d is in the range of 3-5.5, e is in the range of 2.5-.5, f is in the range of 0.2-1, and g is in the range of 0.6-0.9. The catalytic activity and selectivity of the prepared catalyst can be improved by optimizing the amount of metal elements.

[0024] In a further example of the present invention, the performance of the alkaline silica sol is explored and optimized.

[0025] Optionally, the molar ratio of Si element in the alkaline silica sol to Mo element in the metal salt solution is (3.5-4):1. Optionally, the pH value of the alkaline silica sol is 9-11, which can improve the activity and selectivity of the catalyst, enhance the stability of the catalyst, and reduce the degradation or deactivation of the catalyst during storage and use. Optionally, the particle size of the alkaline silica sol is 8-25nm. Using a relatively small particle size can increase the specific surface area of ​​the silica sol, thereby providing more active sites and enhancing the catalytic efficiency of the prepared catalyst.

[0026] In a further example of the present invention, a slurrying operation can be optionally performed after mixing the metal salt solution, alkaline silica sol and SAPO34 molecular sieve slurry to promote uniform dispersion of the materials; the temperature of the slurrying operation is preferably 75-90°C, and the time is preferably 1 to 4.5 hours to promote the maturation of the mixed materials to obtain the precursor slurry.

[0027] In a further example of the present invention, the control conditions of the calcination operation are explored and optimized. Optionally, the calcination operation adopts a step temperature, initially heating to 350-390°C at 1-5°C / min, and maintaining for 2-12h for calcination; then continuing to heat to 550-590°C at 3-5°C / min, and maintaining for 2-24h to activate the catalyst, which is beneficial to improving the catalytic activity of the prepared catalyst and improving the stability of the catalyst.

[0028] The precursor slurry is subjected to granulation and drying operations to obtain dry particles. In a further example of the present invention, the particle size of the dry particles obtained after granulation and drying can be selected to be 40-80 μm, which is the average particle size. It should be noted that the present invention does not limit the equipment used for the granulation and the specific operation method. Those skilled in the art can select suitable granulation equipment and operating conditions through non-creative labor, and the technical solutions formed thereby are all within the scope of protection of the present invention. Optionally, a centrifugal spray drying tower or a centrifugal granulator is used for spray granulation.

[0029] In the roasting operation, the dried particles after granulation and drying are roasted and activated. It should be noted that the present invention does not limit the equipment for the roasting operation. Those skilled in the art can select a rotary roasting furnace, a tubular heating furnace, a vertical furnace, a horizontal furnace, etc. through non-creative labor, and a rotary roasting furnace can be selected for roasting. The technical solutions formed thereby are all within the protection scope of the present invention.

[0030] Optionally, the roasting operation is carried out in a rotary roasting furnace, which has an air inlet and an air outlet, and is equipped with a tail gas absorption device to absorb the discharged acid gas; further optionally, the rotary kiln can rotate at a speed of 0.5-5rpm, and the contact material material is metal, and further optionally, duplex steel or 310s material.

[0031] On the other hand, the present invention provides a catalyst for synthesizing acrylonitrile prepared by the catalyst preparation method.

[0032] Furthermore, the average particle size of the catalyst for synthesizing acrylonitrile is 50-70 μm.

[0033] On the other hand, the present invention provides a method for synthesizing acrylonitrile, wherein propylene, ammonia and air are used as raw materials to react in the presence of the above catalyst to obtain the acrylonitrile.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows: the preparation method of the catalyst for synthesizing acrylonitrile of the present invention adopts three groups of metal element oxides as active components, and in the preparation process, SAPO34 molecular sieve is added to the metal salt solution of specific components in the form of slurry, and then the catalyst is obtained through granulation, drying and calcination activation. The preparation method is not only very simple to operate, but also significantly improves the catalytic activity and acrylonitrile selectivity of the prepared catalyst, and is suitable for the process of large-scale propylene ammoxidation method for producing acrylonitrile. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0036] Figure 1 A scanning electron microscope image of the SAPO34 molecular sieve in the SAPO34 molecular sieve slurry prepared in Example 3 is shown;

[0037] Figure 2 A microscopic image of the catalyst for synthesizing acrylonitrile prepared in Example 3 is shown. DETAILED DESCRIPTION

[0038] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively below, and preferred embodiments of the present invention are given. However, it should be understood that these embodiments are only used for more detailed description, and should not be understood as limiting the present invention in any form, that is, they are not intended to limit the scope of protection of the present invention. Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by technicians in the field to which the present invention belongs. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods, unless otherwise specified, are all conventional methods.

[0039] The application of the catalyst for synthesizing acrylonitrile prepared in the embodiment of the present invention in the reaction of synthesizing acrylonitrile and the test method of the performance evaluation method are as follows:

[0040] Specifically, the propylene ammoxidation reaction was catalyzed in a DN50 fixed fluidized bed device at a reaction temperature of 440°C and a space velocity of 0.08 h -1 , wherein the feed propylene: ammonia: air = 1: 1.2: 9.3; after the reaction is completed, the propylene conversion rate and the selectivity of acrylonitrile, acetonitrile, hydrocyanic acid, acrolein, acrylic acid, and CO+CO2 are detected;

[0041] Among them, propylene conversion rate = 100% - (propylene concentration in the gas at the rear end of the reactor × gas flow rate at the rear end of the reactor) / propylene feed amount; acrylonitrile selectivity = (acrylonitrile concentration in the gas at the rear end of the reactor × gas flow rate at the rear end of the reactor) / (propylene feed amount × propylene conversion rate); in addition, the selectivity calculation method of acetonitrile, hydrocyanic acid, acrolein, acrylic acid, and CO+CO2 is the same as the acrylonitrile selectivity technical method.

[0042] Example 1

[0043] A method for preparing a catalyst for synthesizing acrylonitrile, comprising the following steps:

[0044] (1) dissolving 530 g of ammonium molybdate in 700 g of desalted water to obtain a molybdenum salt solution; dissolving 59.9 g of bismuth nitrate, 560.1 g of nickel nitrate, 30.5 g of cerium nitrate, 182 g of iron nitrate, 91.5 g of magnesium nitrate and 7.7 g of potassium nitrate in 600 g of desalted water to obtain other metal salt solutions except molybdenum; combining the two salt solutions to obtain the metal salt solution;

[0045] (2) adding 1750 g of alkaline silica sol to the metal salt solution, mixing them uniformly to obtain a first solution in the form of a suspension, wherein the pH value of the alkaline silica sol is 10 and the particle size is 20 nm; and then adding SAPO34 molecular sieve slurry to the first solution, mixing them uniformly to obtain a precursor slurry;

[0046] The mass of the SAPO34 molecular sieve in the SAPO34 molecular sieve slurry is about 1% of the mass of the prepared catalyst, the silicon-aluminum ratio of the SAPO34 molecular sieve is 0.2, and the phosphorus-aluminum ratio is 0.8; the particle size of the SAPO34 molecular sieve is 0.3-2 μm; the SAPO34 molecular sieve slurry is prepared by the following method: triethylamine, diethylamine, and n-butylamine are used as templates, and silica sol and ethyl orthosilicate are used in a ratio of 1:1 as silicon sources, pseudo-boehmite as aluminum sources, 85% phosphoric acid is used as a phosphorus source, and the molar ratio of the template to Al2O3 is 1.55 according to the silicon-aluminum ratio and the phosphorus-aluminum ratio is 0.8, and the water of 4 times the mass of the alumina is uniformly mixed to obtain an initial glue solution, and the initial glue solution is crystallized at 200°C and 3MPa for 24 hours; after the crystallized material is evaporated in situ to remove the free liquid template, the original powder slurry is centrifuged, the solid is collected, and washed three times with 1 times the water; the washed original powder slurry is beaten to obtain a SAPO34 molecular sieve slurry in a suspended liquid state;

[0047] (3) The precursor slurry is input into a spray granulation tower for drying, the inlet temperature of the granulation tower is 300°C, and the outlet temperature is above 110°C, to obtain dry particles with an average particle size of 60 μm; the dry particles are then calcined and activated in a rotary calciner, initially the temperature is increased to 380°C at 5°C / min and maintained for 2 hours; then the temperature is continued to be increased to 550°C at 3°C / min and maintained for 2 hours to obtain a catalyst for synthesizing acrylonitrile, the particle size of the catalyst is 50 to 70 μm.

[0048] Further testing of the performance of this catalyst in catalyzing the synthesis of acrylonitrile revealed a propylene conversion rate of 99.6%, acrylonitrile selectivity of 79.33%, acetonitrile selectivity of 2.84%, hydrocyanic acid selectivity of 4.43%, acrolein selectivity of 0.92%, acrylic acid selectivity of 0.58%, and CO+CO2 selectivity of 11.92%.

[0049] Example 2

[0050] Based on the preparation method of the catalyst for synthesizing acrylonitrile shown in Example 1, the silicon-to-aluminum ratio and preparation conditions of the SAPO34 molecular sieve used were explored and optimized in this example.

[0051] The parameters and control conditions for the preparation of the catalyst in this example are the same as those in Example 1, except for the silicon-to-aluminum ratio, phosphorus-to-aluminum ratio and preparation conditions of the SAPO34 molecular sieve used. Table 1 shows the results of catalytic synthesis of acrylonitrile by the catalysts prepared for synthesizing acrylonitrile under different silicon-to-aluminum ratios, phosphorus-to-aluminum ratios and preparation conditions in Example 1, Example 2.1 to Example 2.3, and Comparative Examples 1.1-1.2.

[0052] Table 1

[0053]

[0054] Example 3

[0055] A method for preparing a catalyst for synthesizing acrylonitrile, comprising the following steps:

[0056] (1) dissolving 530 g of ammonium molybdate in 700 g of desalted water to obtain a molybdenum salt solution; dissolving 59.9 g of bismuth nitrate, 560.1 g of nickel nitrate, 30.5 g of cerium nitrate, 182 g of iron nitrate, 91.5 g of magnesium nitrate and 7.7 g of potassium nitrate in 600 g of desalted water to obtain other metal salt solutions except molybdenum; combining the two salt solutions to obtain the metal salt solution;

[0057] (2) 1750 g of alkaline silica sol is input into the metal salt solution, and after uniform mixing, a first solution in the form of a suspension is obtained, wherein the pH value of the alkaline silica sol is about 10 and the particle size is 20 nm; and then SAPO34 molecular sieve slurry is input into the first solution, and the slurry is continued at 90° C. for 4.5 hours, and uniform mixing is performed to obtain the precursor slurry. The mass of SAPO34 molecular sieve in the SAPO34 molecular sieve slurry is about 1% of the mass of the prepared catalyst, the silicon-aluminum ratio of the SAPO34 molecular sieve is 0.2, and the phosphorus-aluminum ratio is 0.8; the particle size of the SAPO34 molecular sieve is 0.3-2 μm; wherein the SAPO34 molecular sieve slurry is prepared by the method used in Example 2.2.

[0058] (3) The precursor slurry is input into a spray granulation tower for drying, the inlet temperature of the granulation tower is 300°C, and the outlet temperature is above 110°C, to obtain dry particles with an average particle size of 40-80 μm. The dried particles are then roasted and activated in a rotary roasting furnace, initially heated to 380°C at 5°C / min and maintained for 2 hours; then heated to 590°C at 3°C / min and maintained for 2 hours, to obtain a catalyst for synthesizing acrylonitrile, the particle size of the catalyst is 50-70 μm. The performance of this catalyst in catalyzing the synthesis of acrylonitrile is shown in Table 2.

[0059] Embodiment 4-7

[0060] Examples 4 to 7 respectively demonstrate methods for preparing catalysts for synthesizing acrylonitrile under different working conditions. The overall preparation process and parameter control of the method are the same as those of Example 3, but the pH value and particle size of the alkaline silica sol used, as well as the temperature and time of the slurrying operation after mixing the metal salt solution, alkaline silica sol and SAPO34 molecular sieve slurry are regulated; the specific parameter control and the performance of the catalyst in catalyzing the synthesis of acrylonitrile are shown in Table 2.

[0061] Comparative Example 2

[0062] A method for preparing a catalyst for synthesizing acrylonitrile, wherein the preparation process and parameter control of the method are the same as those of Example 3, except that no SAPO34 molecular sieve slurry is added in step (2), and the first solution is granulated, dried and calcined to obtain the catalyst. The performance of the catalyst for synthesizing acrylonitrile is shown in Table 2.

[0063] Comparative Example 3

[0064] A method for preparing a catalyst for synthesizing acrylonitrile, wherein the preparation process and parameter control of the method are the same as those of Example 3, except that commercially available SAPO34 molecular sieve is added in step (2), and the first solution is granulated, dried and calcined to obtain the catalyst. The performance of the catalyst in synthesizing acrylonitrile is shown in Table 2.

[0065] Table 2

[0066]

[0067]

[0068] It should be noted that the above contents are further detailed descriptions of the present invention in combination with specific implementation methods, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions; the dimensional data of this embodiment does not necessarily limit the technical solution, but only shows one of the specific working conditions. For ordinary technicians in the technical field to which the present invention belongs, several simple improvements and modifications can be made without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.

Claims

1. A method for preparing a catalyst for synthesizing acrylonitrile, characterized in that: The metal salt solution, alkaline silica sol and SAPO34 molecular sieve slurry are uniformly mixed to obtain a precursor slurry; the precursor slurry is granulated, dried and calcined to obtain the catalyst for synthesizing acrylonitrile; Wherein, the general formula of the metal salt solution in terms of metal element is Mo 30 Bi b Ni c Fe d Mg e B f C g , wherein B includes one or more of aluminum, lithium, sodium, and potassium, and C includes one or more of lanthanum, cerium, praseodymium, scandium, and yttrium.

2. The method for preparing a catalyst for synthesizing acrylonitrile according to claim 1, characterized in that: The amount of SAPO34 molecular sieve added to the SAPO34 molecular sieve slurry is 0.5%-1.5% of the catalyst mass; And / or, the SAPO34 molecular sieve has a silicon-to-aluminum ratio of 0.2-0.32 and a phosphorus-to-aluminum ratio of 0.6-1; And / or, the particle size of the SAPO34 molecular sieve in the SAPO34 molecular sieve slurry is 0.3-2 μm.

3. The method for preparing a catalyst for synthesizing acrylonitrile according to claim 1, characterized in that: The SAPO34 molecular sieve slurry preparation process comprises: preparing an initial gel solution containing an aluminum source, a silicon source, a phosphorus source, a template and water; and obtaining the SAPO34 molecular sieve slurry by crystallizing and washing the initial gel solution; Wherein, the template agent is one or more of triethylamine, diethylamine, and n-butylamine; the molar ratio of the template agent to Al2O3 in the SAPO34 molecular sieve is 1.2-1.

8.

4. The method for preparing a catalyst for synthesizing acrylonitrile according to claim 3, characterized in that: The silicon source includes one or more of sodium silicate, ethyl orthosilicate, methyl orthosilicate, propyl orthosilicate, and silica sol; Preferably, the silicon source includes silica sol and tetraethyl orthosilicate; Further preferably, the mass ratio of the silica sol to tetraethyl orthosilicate is 1:1-1:3; And / or, the aluminum source includes one or more of aluminum sulfate, aluminum nitrate, pseudo-boehmite, dry glue, aluminum oxide, aluminum isopropoxide, aluminum hydroxide, and activated alumina; And / or, the phosphorus source includes one or more of phosphoric acid, phosphorous acid, hypophosphorous acid, ammonium phosphate, monoammonium hydrogen phosphate and diammonium phosphate.

5. The method for preparing a catalyst for synthesizing acrylonitrile according to claim 1, characterized in that: In the general formula, b is in the range of 0.8-2.2, c is in the range of 7-15, d is in the range of 3-5.5, e is in the range of 2.5-.5, f is in the range of 0.2-1, and g is in the range of 0.6-0.

9.

6. The method for preparing a catalyst for synthesizing acrylonitrile according to claim 1, characterized in that: In terms of elements, the molar ratio of Si element in the alkaline silica sol to Mo element in the metal salt solution is (3.5-4):1; Preferably, the pH value of the alkaline silica sol is 9-11; Preferably, the particle size of the alkaline silica sol is 8-25 nm.

7. The method for preparing a catalyst for synthesizing acrylonitrile according to claim 1, characterized in that: The metal salt solution, the alkaline silica sol and the SAPO34 molecular sieve slurry are mixed and then slurried at a temperature of 75 to 90° C. for 1 to 4.5 hours; And / or, the calcination adopts a step temperature, initially the temperature is increased to 350-390°C at 1-5°C / min, and maintained for 2-12h; then the temperature is further increased to 550-590°C at 3-5°C / min, and maintained for 2-24h.

8. The method for preparing a catalyst for synthesizing acrylonitrile according to claim 1, characterized in that: The average particle size of the dried particles obtained after granulation and drying is 40-80 μm.

9. A catalyst for synthesizing acrylonitrile prepared by the preparation method according to any one of claims 1 to 8; Preferably, the particle size of the catalyst is 50-70 μm.

10. A method for synthesizing acrylonitrile, characterized in that: In the presence of the catalyst according to claim 9, propylene, ammonia and air are used as raw materials to react and obtain the acrylonitrile.

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