Ammoxidation catalyst, and preparation method therefor and use thereof

Abstract

Disclosed in the present invention are an ammoxidation catalyst, and a preparation method therefor and the use thereof. The active component of the catalyst is represented by general formula MoxBiaFebAcBdCeDfEgFhOy, wherein A represents at least one element selected from a combination of nickel, cobalt, manganese, zinc and cadmium; B represents at least one element selected from a combination consisting of magnesium, strontium and barium; C represents at least one element selected from a combination consisting of potassium, rubidium and cesium; D represents at least one element selected from a combination of tungsten, vanadium, chromium, gallium, germanium, scandium, yttrium, indium, tin and antimony; E represents at least one element of lanthanide elements other than promethium; and F represents at least one element of platinum group elements. In the present invention, the composition proportion of the active component of the catalyst is adjusted and controlled according to the action mechanism of a metal catalyst, thereby improving the comprehensive performance of the catalyst and achieving a relatively high trinitrile product yield and a relatively low trinitrile production material consumption.

Description

Ammonia oxidation catalyst, its preparation method and application Technical Field

[0001] This invention relates to the field of catalysis technology, specifically to an ammonia oxidation catalyst, its preparation method, and its application. Background Technology

[0002] Numerous complex oxide catalysts containing molybdenum, bismuth, and iron have been developed and used to produce substances such as acrolein, acrylic acid, acrylonitrile, acetonitrile, and hydrogen cyanide. This process involves the catalytic oxidation of propylene under ammonia and oxygen conditions. Other examples include the ammoxidation of propane to acrylonitrile and the ammoxidation of ethanol to acetonitrile.

[0003] Chinese patent document CN115501882A discloses a catalyst for the ammoxidation of propylene to acrylonitrile, its preparation method, and its application. This catalyst not only exhibits a high acrylonitrile yield under high propylene loading but also a low acrolein yield, resulting in a high acrylonitrile recovery rate and improved production efficiency and economic benefits. It can be used in the industrial production of acrylonitrile. Chinese patent document CN1054914A discloses a fluidized bed catalyst for the ammoxidation of propylene to produce acrylonitrile. This catalyst, in addition to its high activity and selectivity for acrylonitrile production, is particularly suitable for catalytic reactions of air and propylene under low ratio conditions, thus significantly increasing reactor production capacity. Chinese patent document CN1379759A discloses a method for achieving high yield and maintaining this effect over a long period through the ammoxidation of propylene to acrylonitrile. This method utilizes a fluidized bed catalyst and appropriately adds a molybdenum-containing material during the reaction. Chinese patent document CN101534945B discloses a fluidized bed catalyst for acrylonitrile production that can maintain a high acrylonitrile yield for a long time, and a method for manufacturing acrylonitrile using this catalyst. Chinese patent document CN 101168129B discloses a catalyst for the ammoxidation of olefins to produce unsaturated nitriles, which can produce unsaturated nitriles under conditions of high catalyst loading, high reaction pressure, low reaction temperature, low olefin ratio, and low ammonia-olefin ratio. Chinese patent document CN107282064B discloses a catalyst and preparation process for the production of acrylonitrile, using silica and a support modifier, primarily addressing the problems of low selectivity and poor stability of existing catalysts used for the ammoxidation of propylene.

[0004] While the catalysts disclosed in the aforementioned patent documents have significantly improved the yield of the main product in the initial stage of the reaction, they only propose different combinations of metal source compounds in the ammonia oxidation catalyst, without clarifying the catalytic mechanism of such multi-element catalysts or the influence of combinations of other metal elements besides molybdenum, bismuth, and iron on the ammonia oxidation catalysis. Some of the added metal element combinations are clearly unsuitable for oxidation reactions and instead negatively impact the catalyst activity. Therefore, current known methods for preparing ammonia oxidation catalysts lack in-depth research on other metal elements besides molybdenum, bismuth, and iron in the ammonia oxidation catalytic system.

[0005] In addition, there are some problems with the actual industrial use of ammonia oxidation catalysts, including:

[0006] 1. Initially, the product yield is relatively high, but it gradually decreases after a certain period. This is due to various factors, including reactor design, reaction condition control, and catalyst loss during the fluidized bed reaction. Catalyst loss during the fluidized bed reaction is a key factor because catalyst particles easily collide and come into contact with each other in the fluidized reactor, inevitably causing particle abrasion or breakage. This leads to an increase in the amount of fine powder in the reactor, which is then carried out by the reaction gas stream, resulting in a total catalyst loss. Generally, a wear index exceeding 8.0 for commercial catalysts indicates a high catalyst loss rate. For acrylonitrile catalysts, this wear index should typically not exceed 4.0; the lower the value, the better the anti-wear performance and the longer the catalyst life. Therefore, developing catalysts with low wear indices is an important goal in the industry.

[0007] 2. Besides wear and tear, molybdenum, as a key element in the catalyst, undergoes sublimation at the ammonia oxidation catalytic reaction temperature, leading to a significant loss of molybdenum from the catalyst system. While some published patents propose methods for replenishing the catalyst bed with molybdenum-containing substances in fluidized bed reactors, which can restore some catalyst activity and prolong catalyst life during the fluidized reaction, frequent addition of molybdenum-containing substances does not address the fundamental problem of substantial catalyst loss due to wear and tear. This method also leads to a gradual decrease in catalyst activity over prolonged use and a continuous increase in operating costs. Therefore, utilizing the properties of different co-catalyst metal elements to improve the microstructure of the catalyst can also help reduce molybdenum loss during the reaction process.

[0008] 3. When evaluating the performance of ammonia oxidation catalysts, taking acrylonitrile catalysts as an example, most previously published patent literature technologies aimed for high propylene conversion, high acrylonitrile selectivity, and high acrylonitrile product yield, while also ensuring that byproducts acetonitrile and hydrogen cyanide were within a certain low yield range. However, this evaluation method actually needs to be adjusted in a timely manner according to the downstream market demand of different products in practical industrial applications. Ultimately, the comprehensive performance of the catalyst should be evaluated based on market demand and economic benefits. Summary of the Invention

[0009] To address the problems existing in the prior art, this invention aims to provide a highly efficient ammonia oxidation catalyst and its preparation method. For the ammonia oxidation catalytic reaction of propylene, the invention mainly focuses on controlling the composition ratio of the active components of the catalyst from the action mechanism of metal catalysts, which has not been addressed in previous technologies. On the one hand, it increases the migration rate of lattice oxygen in the catalyst system, and on the other hand, it increases the structural strength of the catalyst and correspondingly improves the anti-wear performance of the catalyst. Under certain preparation and synthesis conditions and certain reaction evaluation conditions, the comprehensive performance of the highly efficient ammonia oxidation catalyst of this invention was evaluated, showing a high trinitrile product yield and relatively low trinitrile production and material consumption.

[0010] To achieve one of the above objectives and provide an ammonia oxidation catalyst, the present invention adopts the following technical solution:

[0011] An ammonia oxidation catalyst, wherein the active component of the catalyst is composed of the general formula Mo. x Bi a Fe b A c B d C e D f E g F h O y This indicates that in the general formula:

[0012] Mo, Bi, Fe, and O represent molybdenum, bismuth, iron, and oxygen, respectively.

[0013] A represents at least one element selected from the combination of nickel, cobalt, manganese, zinc, and cadmium.

[0014] B represents at least one element selected from the combination of alkaline earth metal elements consisting of magnesium, strontium, and barium;

[0015] C represents at least one element selected from the combination of alkali metal elements consisting of potassium, rubidium, and cesium;

[0016] D represents at least one element selected from the combination of tungsten, vanadium, chromium, gallium, germanium, scandium, yttrium, indium, tin, and antimony.

[0017] E represents at least one element selected arbitrarily from the lanthanides, excluding promethium.

[0018] F represents at least one element selected from the platinum group elements;

[0019] a, b, c, d, e, f, g, h, and y represent the number of atoms of the metal elements Bi, Fe, A, B, C, D, E, and F, and oxygen, respectively.

[0020] x is the number of molybdenum atoms, and x can take any integer value greater than 1, which is used as the baseline value;

[0021] The value of 'a' is a multiple of x, and the range of multiples of 'a' is 0.03 to 0.07.

[0022] b takes the value of a multiple of x, and the multiples of b range from 0.12 to 0.31.

[0023] c takes the value of a multiple of x, and the multiple of c ranges from 0.3 to 0.5;

[0024] d takes the value of a multiple of x, and the multiples of d range from 0.05 to 0.2;

[0025] e takes the value of a multiple of x, and the multiples of e range from 0.01 to 0.06;

[0026] f takes the value of a multiple of x, and the multiple of f ranges from 0.01 to 0.05;

[0027] g takes the value of a multiple of x, and the multiples of g range from 0.01 to 0.1;

[0028] h takes the value of a multiple of x, and the multiple of h ranges from 0.0001 to 0.001;

[0029] The value of y is the total number of oxygen atoms required to satisfy the requirements of each element compound in the catalyst.

[0030] Preferably, the atomic number relationship of each metal element is expressed by the following formula: M = (number of Mo atoms × 2) / (∑number of atoms of other metal elements × valence of the corresponding metal element)

[0031] Where M represents the ratio obtained by dividing the product of the valence of molybdate and the number of molybdenum atoms by the sum of the products of the corresponding valences and the number of atoms of the other metal components;

[0032] The value of M ranges from 0.88 to 1.2.

[0033] Furthermore, M takes values ​​from 0.93 to 1.05.

[0034] Preferably, B is one of magnesium and strontium; C is one of rubidium and cesium; D is one of tungsten and chromium; E is one of lanthanum and cerium; and F is one of platinum and ruthenium.

[0035] Preferably, the catalyst further includes a support, and the amount of the support used accounts for 40 to 60 wt% of the total mass of the catalyst.

[0036] A second objective of this invention is to provide a method for preparing the aforementioned ammonia oxidation catalyst, the method comprising the following steps:

[0037] The raw materials of various metal elements constituting the catalyst and the carrier raw materials are mixed in advance to prepare an aqueous slurry. The aqueous slurry is then dehydrated and dried, and the dried product is calcined to finally obtain the catalyst product.

[0038] Preferably, the raw materials for the metal elements are selected from the following forms of each metal element: oxides or nitrates, ammonium salts, and hydroxides.

[0039] Preferably, the calcination temperature is 550-650℃ and the calcination time is 2-4 hours.

[0040] A third objective of this invention is to provide an application of the aforementioned ammonia oxidation catalyst, wherein the catalyst is applied to the ammonia oxidation catalytic reaction of propylene, ammonia, and oxygen. Under certain reaction temperature and pressure, propylene, ammonia, and a gas containing molecular oxygen react in a fluidized bed reactor packed with the catalyst to convert propylene into acrylonitrile, acetonitrile, hydrogen cyanide, or other related products.

[0041] The beneficial effects of this invention are:

[0042] (1) The key technology of the catalyst of this invention is to clarify the main roles of molybdenum and bismuth in the ammonia oxidation catalytic reaction from the perspective of reaction mechanism. By using other metal element components in a certain ratio to optimize and regulate the existing catalyst system, the catalytic performance of the catalyst can be significantly improved, the yield of trinitrile product can be increased, a high yield of trinitrile can be maintained in acrylonitrile production, and the molybdenum loss rate is low.

[0043] (2) The key technology of the catalyst in this invention is to maintain the migration rate of lattice oxygen in the catalyst system by controlling the proportion of specific metal oxides in the catalyst. The selection of metal elements should be based on three principles, in order of priority, without affecting the catalyst performance: variable valence metals > metals with ionic radii no greater than the bismuth ion radius > metals with empty d-electron orbitals. By selecting metals in this way, and controlling the proportions, the activity of the catalyst and the yield of trinitrile can be significantly improved.

[0044] (3) The key to the catalyst of this invention is the addition of a small proportion of auxiliary metal elements, which can improve the dispersion of key elements in the catalyst, prevent coking during calcination, enhance the structural stability of the catalyst, and increase the specific surface area of ​​the catalyst, etc., such as adding small amounts of alkali metals, alkaline earth metals, transition metal elements, rare metals, etc. In addition, this invention also proposes to avoid the presence of metal elements in the catalyst system, such as lithium, sodium, titanium, zirconium, aluminum, etc., as these metal elements are prone to polymerization in the catalytic system, which reduces the catalytic activity.

[0045] (4) The key to the catalyst of this invention is the introduction of new performance evaluation indicators, including total trinitrile yield, trinitrile production material consumption, and trinitrile production value material consumption. Instead of using acrylonitrile yield and propylene conversion rate as the performance evaluation indicators of the catalyst, it fully considers the total yield of trinitrile products and the overall economic benefits. This not only provides a new comprehensive performance evaluation standard for the catalyst, but also takes into account the economic applicability of the catalyst. Detailed Implementation

[0046] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to the methods of the present invention. The preferred embodiments and materials described herein are for illustrative purposes only.

[0047] Unless otherwise specified, "%" in this invention refers to mass percentage. All substances used as raw materials in the examples were obtained through purchase.

[0048] To further understand this invention, before providing specific embodiments, based on in-depth research on metal catalysts in this technical field and combined with the latest internationally recognized ammonia oxidation catalytic mechanism, the reaction mechanism of the catalyst of this invention for catalyzing the ammonia oxidation of propylene to produce acrylonitrile, acetonitrile, hydrogen cyanide, and other products is as follows:

[0049] Physical adsorption processes occur at the [Bi] sites of the catalyst, including the adsorption of products such as propylene, ammonia, intermediate products, acrylonitrile, acetonitrile, and hydrogen cyanide, as well as other by-product molecules. The adsorption effect is achieved by providing the electron density of the lone pairs on the above molecules to the poorly coordinated Bi cations. Taking the adsorption and dehydrogenation process of propylene as an example, the propylene molecule adsorbed at the [Bi] site has a hydrogen atom captured by the adjacent [Mo=O] site to form [Mo-OH], while the remaining π-allyl radical continues to be adsorbed at the [Bi] site; [Mo-OH] is oxidized by external oxygen molecules (hereinafter referred to as "lattice oxygen") and dehydrated to return to the [Mo=O] form, a process called "lattice oxygen migration"; the π-allyl radical adsorbed at the Bi site combines with the adjacent [Mo=O] to form [Mo-O-CH2-CH=CH2]; furthermore, under certain ammonia conditions, ammonia molecules are also adsorbed on the surface of the [Bi] site, and the ammonia molecules adsorbed at the [Bi] site react with the [Mo-O-CH2-CH=CH2] formed after propylene dehydrogenation to generate the intermediate product allylamine (CH2=CH-CH2). -NH2); the intermediate allylamine continues to be adsorbed on the [Bi] site, and a hydrogen atom is captured by the adjacent [Mo=O] site, and then further combines with another adjacent [Mo=O] site to form [Mo-O-CHNH2-CH=CH2]; the intermediate at the [Mo] site is further captured by three different adjacent [Mo=O] sites three times in a row to form [Mo-O-CN-CH=CH2], in which [Mo-OH] is oxidized to [Mo=O] by lattice oxygen each time during these three dehydrogenation processes, and the hydrogen atom is released in the form of water; then, acrylonitrile (CH2=CH-C≡N) is removed from the [Mo] site, and the [Mo] site becomes reduced, and it is further oxidized by lattice oxygen and dehydrated to the [Mo=O] form, and finally the catalyst returns to its initial form. The formation mechanisms of acetonitrile and hydrogen cyanide are similar to those of acrylonitrile, with the difference being that an ammonia molecule adsorbed at the [Bi] site reacts with an allylamine group at the [Mo] site [Mo-O-CHNH2-CH=CH2] to form [Mo-O-CHNH2-CHNH2-CH3]. Then, the carbon-carbon double bond breaks, forming [Mo-O-CHNH2] at the original [Mo] site, while [-CHNH2-CH3] combines with an adjacent new [Mo=O] to form [Mo-O-CHNH2-CH3]. Further, the latter undergoes two dehydrogenation reactions, with acetonitrile (CN-CH3) detaching from the new [Mo=O]. The former, after two dehydrogenation reactions, detaches hydrogen cyanide (HCN) from the original [Mo] site. The two desorbed [Mo] sites, now in a reduced state, can be further oxidized by lattice oxygen and dehydrated back to the [Mo=O] state. Finally, the catalyst returns to its initial state. This is the formation mechanism of trinitrile.

[0050] As can be seen from the above reaction mechanism, under the catalysis of this catalyst, propylene undergoes ammoniation at the bismuth-molybdenum sites in the presence of both lattice oxygen and ammonia. Through further reaction of the intermediate allylamine, acrylonitrile is ultimately produced, along with byproducts acetonitrile and hydrogen cyanide. If there is an excess of external oxygen molecules (lattice oxygen), oxidation reactions will also occur, producing other organic and inorganic oxygen-containing compounds, such as acrolein, acrylic acid, carbon dioxide, and carbon monoxide as byproducts. Therefore, controlling the amount of lattice oxygen in the catalytic system is particularly important.

[0051] Furthermore, based on the above mechanism, it can be concluded that the main reactions are all generated at adjacent [Mo] sites. The original [Mo=O] is transformed into [Mo-OH] after abstracting [H], and then restored to the [Mo=O] form after being oxidized by lattice oxygen, while the [H] atoms are released as water molecules. This process can be summarized as a series of cyclic reactions involving hydrogen abstraction, oxidation, dehydration, and lattice oxygen restoration on [Mo=O], with the oxidation-dehydration reaction providing the thermodynamic driving force for the overall cyclic reaction. Therefore, lattice oxygen migration is the most critical factor in this catalyst system besides the key active elements of molybdenum and bismuth. It can not only improve catalyst performance, but a faster migration rate can also help reduce structural distortions in the catalyst during the reaction.

[0052] The rate of lattice oxygen migration in a catalytic system depends on the composition and crystal structure of the different metal oxides within the system. For example, the transition metal elements in the catalyst possess certain d-band electron vacancies within their metallic bonds. This ability to both gain and lose electrons not only accelerates electron transfer but also enhances the catalyst's chemisorption capacity, further favoring lattice oxygen migration. Furthermore, the ionic radii of divalent and trivalent metal ions in the catalyst also affect the migration rate of lattice oxygen. When the ionic radii are relatively close and both are lower than the bismuth ion radius, the migration rate is more favorable. In certain conditions, divalent metal ions in the catalyst are easily replaced by trivalent metal ions, thus increasing the migration rate of lattice oxygen. Another example is the presence of variable valence metal systems (M...) in the catalyst. n+ / M (n+1)+ Redox pairs, where oxygen vacancies on the surface of reduced metals can accelerate the transfer of electrons and lattice oxygen, are common examples of this type of metal element, particularly iron. Therefore, iron must be present in catalyst systems. In addition, catalysts also contain small amounts of auxiliary metal elements, whose functions include improving the dispersion of key catalyst elements, preventing catalyst coking, enhancing catalyst structural stability, and increasing the catalyst's specific surface area.

[0053] Therefore, optimizing the catalyst formulation and crystal phase structure during catalyst preparation is crucial. This invention conducts an in-depth study of fluidized bed catalysts for ammonia oxidation reactions disclosed domestically and internationally, as well as recognized catalytic reaction mechanisms. Combined with experimental research on adjusting the composition of different metal oxide components in the catalyst and preparing ammonia oxidation catalyst products through specific proportions and synthesis methods, it not only achieves sustained high trinitrile yields but also reduces the loss rate of molybdenum-containing substances.

[0054] Based on the mechanism study of lattice oxygen migration rate, as a preferred embodiment of the present invention, an ammonia oxidation catalyst is provided, wherein the active component of the catalyst is composed of the general formula Mo. x Bi a Fe b A c B d C e D f E g F h O y This indicates that in the general formula:

[0055] Mo, Bi, Fe, and O represent molybdenum, bismuth, iron, and oxygen, respectively.

[0056] A represents at least one element selected from the combination of nickel, cobalt, manganese, zinc, and cadmium.

[0057] B represents at least one element selected from the combination of alkaline earth metal elements composed of magnesium, strontium, and barium, such as at least one element selected from the combination of magnesium, strontium, and barium; preferably, B is either magnesium or strontium.

[0058] C represents at least one element selected from the combination of alkali metal elements consisting of potassium, rubidium, and cesium, such as at least one element selected from the combination of potassium, rubidium, and cesium; preferably, one of rubidium and cesium.

[0059] D represents at least one element selected from the combination of tungsten, vanadium, chromium, gallium, germanium, scandium, yttrium, indium, tin, and antimony; preferably, D is either tungsten or chromium.

[0060] E represents at least one element selected arbitrarily from the lanthanides, excluding promethium; preferably, E is either lanthanum or cerium.

[0061] F represents at least one element selected from the platinum group elements; preferably, F is either platinum or ruthenium.

[0062] For the active component Mo x Bi a Fe b A c B d C e D f E g F h O y In this context, a, b, c, d, e, f, g, h, and y represent the number of atoms of the metal elements Bi, Fe, A, B, C, D, E, and F, and oxygen, respectively.

[0063] x is the number of molybdenum atoms and x can be any integer greater than 1, which is used as the baseline value;

[0064] The value of 'a' is a multiple of x, and the range of multiples of 'a' is 0.03 to 0.07.

[0065] b takes the value of a multiple of x, and the multiples of b range from 0.12 to 0.31.

[0066] c takes the value of a multiple of x, and the multiple of c ranges from 0.3 to 0.5;

[0067] d takes the value of a multiple of x, and the multiples of d range from 0.05 to 0.2;

[0068] e takes the value of a multiple of x, and the multiples of e range from 0.01 to 0.06;

[0069] f takes the value of a multiple of x, and the multiple of f ranges from 0.01 to 0.05;

[0070] g takes the value of a multiple of x, and the multiples of g range from 0.01 to 0.1;

[0071] h takes the value of a multiple of x, and the multiple of h ranges from 0.0001 to 0.001;

[0072] The value of y is the total number of oxygen atoms required to satisfy the requirements of each element compound in the catalyst.

[0073] The atomic number relationships of the above metallic elements are expressed by the following formula:

[0074] M = (Number of Mo atoms × 2) / ∑(Number of other metallic atoms × Valence of the corresponding metallic element)

[0075] Wherein, M represents the proportion obtained by dividing the product of the valence of molybdate and the number of molybdenum atoms by the sum of the products of the corresponding valences and atomic ratios of the other metal components; if the value of M is less than 1, it indicates that the Mo content in the catalyst system is relatively low; if the value of M is greater than 1, it indicates that the Mo content in the catalyst system is relatively high. The value of M ranges from 0.88 to 1.2M. Preferably, the value is from 0.93 to 1.05.

[0076] Based on this implementation method, the addition of an appropriate amount of metal element A not only effectively improves the specific surface area and stability of the catalyst as a structural aid, but also forms a solid solution phase with bismuth molybdate salt during catalyst calcination, which helps to improve the selectivity of the catalyst for low-carbon olefins. The addition of a small amount of alkaline earth metal B can strengthen the interaction between metal oxides such as molybdenum bismuth iron and the silica sol support, which is beneficial for promoting the uniform dispersion of other active components on the support surface, thereby improving the activity of the catalyst. The appropriate addition of alkali metal element C not only helps the catalyst eliminate acid sites, but also benefits the migration rate of lattice oxygen, as its relatively large ionic radius contributes to the catalyst calcination process. During activation, lattice distortion and the generation of ion vacancies can easily occur, leading to increased conductivity. However, the amount of alkali metal added should not be too high, as this can cause severe catalyst distortion and reduce activity. Metal element D, as an electronic promoter, possesses electron holes and electron-dense regions; its appropriate addition can reduce electron escape from the catalyst, facilitating the adsorption of reactants (propylene, ammonia) and intermediates, as well as product desorption, further improving catalyst performance. The trace addition of lanthanide metal E promotes the dispersion of elements such as iron and nickel, and lanthanide metal oxides can delay catalyst grain growth and sintering during calcination, further improving catalyst stability. Furthermore, the multivalent state of cerium can promote electron migration within the catalyst, increasing the migration rate of lattice oxygen and enhancing reaction activity. The trace addition of platinum group metal F helps extend catalyst lifetime; due to their high melting point and high density, platinum group metals can further improve the catalyst's thermal stability and wear resistance. Thus, this invention, based on the construction of an appropriate catalytic system and by controlling the effect of lattice oxygen in the catalytic system, can significantly improve catalyst performance and reduce structural distortions generated during the reaction, thereby obtaining a higher yield of trinitrile products and relatively lower trinitrile production and material consumption.

[0077] The catalyst further includes a support, which accounts for 40-60 wt% of the total catalyst mass, preferably 45-55 wt%. The support is made of silica, preferably colloidal silica (also known as "silica sol"). Commercially available silica sol products can be used. The specifications for silica sol selection are as follows:

[0078] The silica content is 30-50 wt%, preferably 33-41 wt%;

[0079] The average particle size ranges from 2 to 100 nm, preferably from 10 to 30 nm. The particle size distribution can have multiple peaks, but a single peak is the optimal choice.

[0080] The specific surface area ranges from 80 to 200 m². 2 / g, preferably 100-150m 2 / g;

[0081] The viscosity range is 8 to 15 cp (@25°C), preferably 10 to 12 cp (@25°C).

[0082] The pH range is 7 to 9.5, with a preferred pH of 8 to 9;

[0083] The ion type is ammonium ion stabilized, and sodium ion stabilized should be avoided because the polymerization effect of sodium ions is not applicable in the catalyst system of this invention. On the contrary, it will have a negative effect and affect the activity of the catalyst.

[0084] The aforementioned commercially available silica sol products can be used as a single carrier or in combination as a carrier.

[0085] As a preferred embodiment of the present invention, a method for preparing an ammonia oxidation catalyst is provided, the method comprising the following steps:

[0086] The raw materials of various metal elements constituting the catalyst and the carrier raw materials are mixed in advance to prepare an aqueous slurry. The aqueous slurry is prepared according to the active phase composition of the catalyst. Then, the obtained aqueous slurry is dehydrated and dried, and the dried product is calcined to finally obtain the catalyst product.

[0087] The raw materials for the metal elements are oxides of various metal elements or nitrates, ammonium salts, and hydroxides that easily transform into oxide forms. Specific metal element raw materials are as follows:

[0088] The raw materials used as molybdenum components can be ammonium metamolybdate, ammonium tetramolybdate, ammonium dimolybdate, molybdenum trioxide, and molybdenum dioxide.

[0089] The raw materials used as bismuth components can be bismuth nitrate or bismuth oxide.

[0090] The raw materials used as iron components can be ferric nitrate, ferric oxide, or ferric hydroxide.

[0091] The raw materials used as nickel components can be nickel nitrate, nickel oxide, or nickel hydroxide.

[0092] The raw materials used as magnesium components can be nickel nitrate, nickel oxide, or nickel hydroxide.

[0093] As a raw material for other metallic element components, it can be the nitrate, ammonium salt, oxide, or hydroxide of the metallic element.

[0094] Depending on actual needs, the raw materials of the above-mentioned metallic elements can be combined in various ways.

[0095] The dehydration and drying method for the aqueous slurry involves converting the aqueous slurry into fine particulate products in the shape of microspheres, i.e., catalyst semi-finished products, while simultaneously evaporating and removing approximately 90-95% of the water. To obtain solid particles with more controllable particle size distribution, a spray dryer is preferred. The spraying method can be a pressure nozzle, an airflow nozzle, or a rotary atomizer. A rotary atomizer is preferred, as it can obtain solid particles with a more uniform particle size distribution. Specifically, the slurry is pumped onto a high-speed rotating dispersion disc. Due to centrifugal force, the liquid is stretched into a thin film on the rotating surface and ejected from the edge of the dispersion disc at an ever-increasing speed, forming droplets. The circumferential speed of the dispersion disc is preferably in the range of 90-140 m / s. The droplets can be dried into solid particles at an operating temperature of 250-350°C. The parameters of spray drying directly affect the particle size distribution, bulk density, and other physical properties of the catalyst. Selecting appropriate spray drying conditions is beneficial for controlling the particle size distribution of the catalyst, including the sprayer rotation speed, feed rate, fan airflow, and inlet and outlet air temperatures. Specific parameters are as follows:

[0096] Atomizer disc rotation speed: 35~55Hz;

[0097] Feed rate: 5–15 mL / min;

[0098] Fan air intake volume: 50~250m³ 3 / h

[0099] Inlet air temperature: 280~350℃;

[0100] Air outlet temperature: 150~190℃.

[0101] The calcination method refers to calcining the spray-dried solid fine particle product, i.e., the catalyst semi-finished product, at a high temperature to further obtain a finished catalyst with a certain specific surface area, pore volume, pore structure, and active phase. The calcination temperature and time directly determine the catalyst's performance. For example, if the calcination temperature is too low or the calcination time is too short, the catalyst's optimal activity will not be fully formed; conversely, if the calcination temperature is too high or the calcination time is too long, the optimal active phase will be destroyed. Both situations will result in a decrease in product yield and an increase in the total amount of by-products.

[0102] The roasting time is controlled within 1 to 6 hours, with the preferred roasting time being 2 to 4 hours.

[0103] The roasting temperature is controlled within the range of 550 to 700°C, with a preferred roasting temperature of 590 to 650°C.

[0104] To further improve catalytic activity:

[0105] A two-stage calcination method can be adopted, in which the catalyst raw material is preheated at a temperature of 200-450℃ for 1-3 hours to decompose the remaining moisture, nitrates, etc., and then calcined at a temperature of 550-700℃.

[0106] Furthermore, a three-stage calcination method can be adopted, which involves preheating at 200-450℃ for 1-3 hours, then heat-treating at 450-550℃ for 1-3 hours to fully decompose the remaining moisture, nitrates, etc. in the catalyst raw material, and finally calcining at 550-700℃.

[0107] The roasting method is preferably a rotary roasting furnace or a flow roasting furnace to ensure that the catalyst particles are in a relatively gentle motion state during the roasting process, so as to prevent the catalyst from agglomerating during the roasting process.

[0108] Preferably, a flowing oxygen-containing atmosphere, preferably air, is used during the roasting process; this allows the catalyst to come into full contact with the flowing air, further promoting the formation of oxides or molybdates with a certain phase structure inside the catalyst particles, and the flowing air can carry away the gaseous nitrogen oxides that are released from the catalyst during the roasting process.

[0109] Based on the above, the preferred preparation method of the present invention is as follows: Deionized water is heated to 65–85°C, and a certain amount of ammonium metamolybdate is added in small batches under uniform stirring. Stirring continues until completely dissolved, and the solution is cooled for later use to obtain a molybdenum-based mother liquor, with the temperature maintained between 45–65°C. Then, silica sol is prepared to form a carrier liquid. The prepared carrier liquid is then added to the molybdenum-based mother liquor at a certain addition rate, with continuous uniform stirring during the addition process to form an initial slurry, maintaining the temperature between 55–65°C. Next, another portion of deionized water is prepared and heated to 65–85°C. Other metal element raw materials are added sequentially under uniform stirring, with continuous stirring until completely dissolved. The solution is then cooled for later use to obtain a soluble metal salt solution, with the temperature maintained between 45–65°C. The prepared soluble metal salt solution is added to the initial slurry at a certain addition rate, with the temperature heated to 75–85°C and continuous uniform stirring during the addition process until the soluble metal salt solution is completely and uniformly mixed with the initial slurry. Then, the mixture is heated to 102–108°C and aged at this temperature for about 10–20 minutes to finally form a catalyst precursor slurry, which is then stored at 65–85°C for later use.

[0110] Then, the spray dryer is started, and the outlet air temperature is preheated to 160-180°C. The catalyst precursor slurry prepared above is fed to the top of the spray dryer at a certain feed rate (e.g., 8-12 mL per minute). The slurry is atomized and dried to form microspheres under a turntable speed of 40-50 Hz.

[0111] Next, the sprayed microspheres are placed in a rotary calcining furnace. The furnace is rotated at a certain speed in a slightly ventilated atmosphere. The catalyst is first calcined at 200–220°C for 30 minutes, then at 400–420°C for 120 minutes, and finally at 600–670°C for 4 hours, completing the catalyst preparation. The catalyst product of this invention is thus obtained.

[0112] As another embodiment of the present invention, an ammonia oxidation catalyst prepared based on the above embodiments of the present invention is used in the ammonia oxidation catalytic reaction of propylene, ammonia, and oxygen. Under certain reaction temperature and pressure, propylene, ammonia, and a gas containing molecular oxygen react in a fluidized bed reactor packed with the catalyst, converting propylene into acrylonitrile, acetonitrile, hydrogen cyanide, or other related products. The fluidized bed reactor is a recognized prior art.

[0113] The performance evaluation of the catalyst of this invention can be carried out in a fluidized bed reactor with a diameter of 1.5 feet, under the following reaction conditions:

[0114] Reaction temperature: 420~440℃;

[0115] Reaction pressure: 80–140 kPa;

[0116] Raw material molar ratio: propylene / ammonia / air (as oxygen) = 1 / (1.05~1.3) / (1.5~2.5);

[0117] Catalyst loading: 400-550g;

[0118] Catalyst loading (WWH): 0.06–0.14 hr -1 Preferably 0.08–0.11hr -1 .

[0119] Based on the practical application requirements of ammonia oxidation catalysts, the performance evaluation indicators of the catalysts in this invention include total trinitrile yield, trinitrile production material consumption, and trinitrile production value material consumption. The three indicators are specifically expressed in the following formulas:

[0120] Total yield of trinitrile (%) = Acrylonitrile yield + Acrylonitrile yield + Hydrocyanic acid yield

[0121] Trinitrogenate production and material consumption (g / g) = Propylene consumption / (Acrylonitrile production + Acetonitrile production + Hydrogen cyanide production)

[0122] Trinitronic production value material consumption (g / yuan) = Propylene consumption / (Acrylonitrile production value + Acetonitrile production value + Hydrogen cyanide production value)

[0123] In the above formula,

[0124] Acrylonitrile yield refers to the molar percentage yield of acrylonitrile, calculated as follows:

[0125] Acrylonitrile yield (mol%) = (moles of acrylonitrile produced / moles of propylene fed) × 100. Acetonitrile yield refers to the molar percentage yield of acetonitrile, calculated as follows:

[0126] Acetonitrile yield (mol%) = (moles of acetonitrile produced / moles of propylene fed) × 100

[0127] Hydrogen cyanide yield refers to the molar percentage yield of hydrogen cyanide, calculated as follows:

[0128] Hydrogen cyanide yield (mol%) = (moles of hydrogen cyanide produced / moles of propylene fed) × 100. Propylene consumption refers to the feed flow rate of propylene in the reactor, in g / h.

[0129] Acrylonitrile production, acetonitrile production, and hydrogen cyanide production refer to the yield of each product. In this invention, they refer to the calculated values, in g / h, derived from the molar number of each product generated after the reactor reaction.

[0130] The output value of acrylonitrile, acetonitrile, and hydrogen cyanide refers to the product of their respective output values ​​and current market prices. It should be noted that, due to market price fluctuations, this invention only provides a new economic indicator evaluation method for ammonia oxidation catalysts; the output value of each product and the material consumption for trinitrile production are not calculated in the evaluation results of the relevant examples.

[0131] Based on the above implementation methods, specific embodiments are provided:

[0132] Example 1

[0133] 1. Preparation and molding process of the catalyst of this invention

[0134] Heat 200 mL of deionized water to 65–85 °C. Add 250 g of ammonium metamolybdate in small, repeated additions while stirring at a constant speed until completely dissolved. Cool the solution and set aside to obtain a molybdenum-based mother liquor, maintaining the temperature between 45–65 °C. Then, prepare 350 g of silica sol with a silica content of 30% and 350 g of silica sol with a silica content of 41%, and mix them evenly to form a carrier solution. Add the prepared carrier solution to the molybdenum-based mother liquor at a rate of 10 mL per minute, stirring continuously at a constant speed to form an initial slurry, while maintaining the temperature between 55–65 °C. Next, prepare another 100 mL of deionized water and heat it to 65–85 °C. While stirring at a constant speed, add 90 g of ferric nitrate nonahydrate, 28 g of bismuth nitrate pentahydrate, 160 g of nickel nitrate hexahydrate, 55 g of magnesium nitrate hexahydrate, 50 g of cerium nitrate hexahydrate, 10 g of chromium nitrate nonahydrate, 8 g of potassium nitrate, and 0.1 g of ruthenium nitrate sequentially. Continue stirring until completely dissolved, then cool and set aside to obtain a soluble metal salt solution, maintaining the temperature between 45–65 °C. Add the prepared soluble metal salt solution to the initial slurry at a rate of 10 mL per minute, heating the temperature to 75–85 °C and stirring continuously at a constant speed until the soluble metal salt solution is completely and evenly mixed with the initial slurry. Then heat to 102–108 °C and age the slurry at this temperature for approximately 10–20 minutes to finally form a catalyst precursor slurry, which is then stored at 65–85 °C for later use.

[0135] The spray dryer is started, and the outlet air temperature is preheated to 160–180°C. The catalyst precursor slurry is fed to the top of the spray dryer at a feed rate of 8–12 mL per minute. The slurry is atomized and dried to form microspheres at a rotary table speed of 40–50 Hz. The sprayed microspheres are then placed in a rotary calcining furnace, and the furnace is rotated at 5 rpm in a low-air-flow atmosphere. The furnace is first calcined at 200–220°C for 30 minutes, then at 400–420°C for 120 minutes, and finally at 600–670°C for 4 hours to complete the catalyst preparation. The catalyst product of this invention is thus obtained.

[0136] The expression for the active composition of the catalyst prepared by the above-described preparation method is as follows:

[0137] Mo x Bi 0.04x Fe 0.16x Ni 0.39x Mg 0.15x K 0.056x Cr (Ⅲ)0.018x Ce (Ⅲ)0.08x Ru 0.0002x O 4x

[0138] 2. Catalyst performance evaluation

[0139] The catalyst obtained in this embodiment was evaluated in a 1.5-foot fluidized bed reactor. The reactor operating temperature was 435±5℃, the operating pressure was 80±5 kPa, and the molar ratio of propylene / ammonia / air was 1 / 1.2 / 9.5. The catalyst loading was 440±5 g. The catalyst loading for propylene was 0.08 WWh. After a stabilization period of more than 20 hours, the reaction products were collected and analyzed. A long-term evaluation test was conducted to obtain the final evaluation results (stability testing of product yield began after 20 hours of reaction, and the final product yield after 400 hours of continuous operation was taken as the test result for each embodiment of the present invention).

[0140] The active composition and performance evaluation results of the catalyst are shown in Table 1.

[0141] Example 2

[0142] Except for reducing the amount of nickel nitrate hexahydrate by 60g in the soluble metal salt solution composition and adding 40g of cobalt nitrate hexahydrate, the catalyst preparation and molding methods were the same as in Example 1. The expression for the active composition of the prepared catalyst is as follows:

[0143] Mo x Bi 0.04x Fe 0.16x Ni 0.24x Mg 0.15x Co 0.1x K 0.056x Cr (Ⅲ)0.018x Ce (Ⅲ)0.08x Ru 0.0002x O 4x

[0144] The catalyst performance evaluation methods are the same as those in Example 1.

[0145] The active composition and performance evaluation results of the catalyst are shown in Table 1.

[0146] Example 3

[0147] Except for reducing the amount of nickel nitrate hexahydrate by 40g in the soluble metal salt solution composition and adding 30g of manganese nitrate, the catalyst preparation method was the same as in Example 1. The active composition of the prepared catalyst is expressed as follows:

[0148] Mo x Bi 0.04x Fe 0.16x Ni 0.29x Mg 0.15x Mn 0.12x K 0.056xCr (Ⅲ)0.018x Ce (Ⅲ)0.08x Ru 0.0002x O 4x

[0149] The catalyst performance evaluation methods are the same as those in Example 1.

[0150] The active composition and performance evaluation results of the catalyst are shown in Table 1.

[0151] Example 4

[0152] Except for reducing the amount of magnesium nitrate hexahydrate by 25g in the soluble metal salt solution composition and adding 15g of strontium nitrate, the catalyst preparation method was the same as in Example 1. The active composition of the prepared catalyst is expressed as follows:

[0153] Mo x Bi 0.04x Fe 0.16x Ni 0.39x Mg 0.08x Sr 0.05x K 0.056x Cr (Ⅲ)0.018x Ce (Ⅲ)0.08x Ru 0.0002x O 4x The catalyst performance evaluation methods are the same as those in Example 1.

[0154] The active composition and performance evaluation results of the catalyst are shown in Table 1.

[0155] Example 5

[0156] Except for reducing the amount of potassium nitrate by 8g in the soluble metal salt solution composition and adding 5g of rubidium nitrate, the catalyst preparation method was the same as in Example 1. The active composition of the prepared catalyst is expressed as follows:

[0157] Mo x Bi 0.04x Fe 0.16x Ni 0.39x Mg 0.15x Rb 0.024x Cr (Ⅲ)0.018x Ce (Ⅲ)0.08x Ru 0.0002x O 4x

[0158] The catalyst performance evaluation methods are the same as those in Example 1.

[0159] The active composition and performance evaluation results of the catalyst are shown in Table 1.

[0160] Example 6

[0161] Except for reducing the amount of rubidium nitrate by 5g and adding cesium nitrate by 5g in the soluble metal salt solution composition, the catalyst preparation method was the same as in Example 1. The active composition of the prepared catalyst is expressed as follows:

[0162] Mo x Bi 0.04x Fe 0.16x Ni 0.39x Mg 0.15x Cs 0.018x Cr (Ⅲ)0.018x Ce (Ⅲ)0.08x Ru 0.0002x O 4x

[0163] The catalyst performance evaluation methods are the same as those in Example 1.

[0164] The active composition and performance evaluation results of the catalyst are shown in Table 1.

[0165] Example 7

[0166] Except for reducing the amount of chromium nitrate nonahydrate by 3g in the soluble metal salt solution composition and adding 1g of chromium trioxide, the catalyst preparation method was the same as in Example 1. The active composition of the prepared catalyst is expressed as follows:

[0167] Mo x Bi 0.04x Fe 0.16x Ni 0.39x Mg 0.15x Rb 0.024x Cr (Ⅲ)0.012x Cr (Ⅵ)0.007x Ce (Ⅲ)0.08x Ru 0.0002x O 4x The catalyst performance evaluation methods are the same as those in Example 1.

[0168] The active composition and performance evaluation results of the catalyst are shown in Table 1.

[0169] Example 8

[0170] Except for reducing the amount of chromium nitrate nonahydrate by 5g in the soluble metal salt solution composition and adding 2g of chromium trioxide, the catalyst preparation method was the same as in Example 1. The active composition of the prepared catalyst is expressed as follows:

[0171] Mo x Bi 0.04x Fe 0.16x Ni 0.39x Mg 0.15x Rb 0.024x Cr (Ⅲ)0.009x Cr(Ⅵ)0.014x Ce (Ⅲ)0.08x Ru 0.0002x O 4x The catalyst performance evaluation methods are the same as those in Example 1.

[0172] The active composition and performance evaluation results of the catalyst are shown in Table 1.

[0173] Example 9

[0174] Except for reducing the amount of chromium nitrate nonahydrate by 8g in the soluble metal salt solution composition and adding 3g of chromium trioxide, the catalyst preparation method was the same as in Example 1. The active composition of the prepared catalyst is expressed as follows:

[0175] Mo x Bi 0.04x Fe 0.16x Ni 0.39x Mg 0.15x Rb 0.024x Cr (Ⅲ)0.004x Cr (Ⅵ)0.021x Ce (Ⅲ)0.08x Ru 0.0002x O 4.1x

[0176] The catalyst performance evaluation methods are the same as those in Example 1.

[0177] The active composition and performance evaluation results of the catalyst are shown in Table 1.

[0178] Example 10

[0179] Except for reducing the amount of chromium nitrate nonahydrate by 10g in the soluble metal salt solution composition and adding 5g of chromium trioxide, the catalyst preparation method was the same as in Example 1. The active composition of the prepared catalyst is expressed as follows:

[0180] Mo x Bi 0.04x Fe 0.16x Ni 0.39x Mg 0.15x Rb 0.024x Cr (Ⅵ)0.035x Ce (Ⅲ)0.08x Ru 0.0002x O 4.1x

[0181] The catalyst performance evaluation methods are the same as those in Example 1.

[0182] The active composition and performance evaluation results of the catalyst are shown in Table 1.

[0183] Example 11

[0184] Except for reducing the amount of cerium nitrate hexahydrate added by 20g and adding 10g of cerium ammonium nitrate to the soluble metal salt solution, the catalyst preparation method was the same as in Example 10. The active composition of the prepared catalyst is expressed as follows:

[0185] Mo x Bi 0.04x Fe 0.16x Ni 0.39x Mg 0.15x Rb 0.024x Cr (Ⅵ)0.035x Ce (Ⅲ)0.049x Ce (Ⅳ)0.013x Ru 0.0002x O 4.1x The catalyst performance evaluation methods are the same as those in Example 10.

[0186] The active composition and performance evaluation results of the catalyst are shown in Table 1.

[0187] Example 12

[0188] Except for reducing the amount of cerium nitrate hexahydrate added by 30g and adding 20g of cerium ammonium nitrate to the soluble metal salt solution, the catalyst preparation method was the same as in Example 10. The active composition of the prepared catalyst is expressed as follows:

[0189] Mo x Bi 0.04x Fe 0.16x Ni 0.39x Mg 0.15x Rb 0.024x Cr (Ⅵ)0.035x Ce (Ⅲ)0.033x Ce (Ⅳ)0.026x Ru 0.0002x O 4.1x The catalyst performance evaluation methods are the same as those in Example 10.

[0190] The active composition and performance evaluation results of the catalyst are shown in Table 1.

[0191] Example 13

[0192] Except for reducing the amount of cerium nitrate hexahydrate added by 40g and adding 30g of cerium ammonium nitrate to the soluble metal salt solution, the catalyst preparation method was the same as in Example 10. The expression for the active composition of the prepared catalyst is as follows:

[0193] Mo x Bi 0.04x Fe 0.16x Ni 0.39x Mg 0.15x Rb 0.024x Cr (Ⅵ)0.035xCe (Ⅲ)0.016x Ce (Ⅳ)0.039x Ru 0.0002x O 4.1x

[0194] The catalyst performance evaluation methods are the same as those in Example 10.

[0195] The active composition and performance evaluation results of the catalyst are shown in Table 1.

[0196] Example 14

[0197] Except for reducing the amount of cerium nitrate hexahydrate by 10g in the soluble metal salt solution composition and adding 10g of lanthanum nitrate, the catalyst preparation and molding methods were the same as in Example 10. The expression for the active composition of the prepared catalyst is as follows:

[0198] Mo x Bi 0.04x Fe 0.16x Ni 0.39x Mg 0.15x Rb 0.024x Cr (Ⅵ)0.035x Ce (Ⅲ)0.065x La 0.016x Ru 0.0002x O 4.1x

[0199] The catalyst performance evaluation methods are the same as those in Example 10.

[0200] The active composition and performance evaluation results of the catalyst are shown in Table 1.

[0201] Example 15

[0202] Except for reducing the amount of ruthenium nitrate added by 0.1 g in the soluble metal salt solution and adding 0.1 g of platinum nitrate, the catalyst preparation method was the same as in Example 10. The active composition of the prepared catalyst is expressed as follows:

[0203] Mo x Bi 0.04x Fe 0.16x Ni 0.39x Mg 0.15x Rb 0.024x Cr (Ⅵ)0.035x Ce (Ⅲ)0.081x Pt 0.0002x O 4.1x

[0204] The catalyst performance evaluation methods are the same as those in Example 10.

[0205] The active composition and performance evaluation results of the catalyst are shown in Table 1.

[0206] Example 16

[0207] Except for the substitution of the soluble metal salt solution composition with 175g of ferric nitrate nonahydrate, 20g of bismuth nitrate pentahydrate, 125g of nickel nitrate hexahydrate, 70g of magnesium nitrate hexahydrate, 6g of potassium nitrate, 5g of chromium nitrate, 5g of cerium nitrate hexahydrate, and 0.4g of ruthenium nitrate, the other catalyst preparation methods were the same as in Example 10. The expression for the active composition of the prepared catalyst is as follows:

[0208] Mo x Bi 0.03x Fe 0.31x Ni 0.3x Mg 0.2x K 0.04x Cr (Ⅲ)0.01x Ce (Ⅲ)0.01x Ru 0.001x O 4x

[0209] The catalyst performance evaluation methods are the same as those in Example 1.

[0210] The active composition and performance evaluation results of the catalyst are shown in Table 1.

[0211] Example 17

[0212] Except for the substitution of the soluble metal salt solution composition with 140g of ferric nitrate nonahydrate, 35g of bismuth nitrate pentahydrate, 130g of nickel nitrate hexahydrate, 35g of magnesium nitrate hexahydrate, 5g of potassium nitrate, 15g of chromium nitrate, 20g of cerium nitrate hexahydrate, and 0.3g of ruthenium nitrate, the other catalyst preparation methods were the same as in Example 10. The expression for the active composition of the prepared catalyst is as follows:

[0213] Mo x Bi 0.05x Fe 0.24x Ni 0.36x Mg 0.1x K 0.03x Cr (Ⅲ)0.03x Ce (Ⅲ)0.03x Ru 0.0007x O 4x

[0214] The catalyst performance evaluation methods are the same as those in Example 1.

[0215] The active composition and performance evaluation results of the catalyst are shown in Table 1.

[0216] Example 18

[0217] Except for the substitution of the soluble metal salt solution composition with 120g of ferric nitrate nonahydrate, 40g of bismuth nitrate pentahydrate, 150g of nickel nitrate hexahydrate, 25g of magnesium nitrate hexahydrate, 6g of potassium nitrate, 2g of rubidium nitrate, 20g of chromium nitrate, 35g of cerium nitrate hexahydrate, and 0.2g of ruthenium nitrate, the other catalyst preparation methods were the same as in Example 10. The expression for the active composition of the prepared catalyst is as follows:

[0218] Mo x Bi 0.06x Fe 0.21x Ni 0.44x Mg 0.07x K 0.04x Rb 0.01x Cr (Ⅲ)0.04x Ce (Ⅲ)0.06x Ru 0.0004x O 4x

[0219] The catalyst performance evaluation methods are the same as those in Example 1.

[0220] The active composition and performance evaluation results of the catalyst are shown in Table 1.

[0221] Example 19

[0222] Except for the substitution of the soluble metal salt solution composition with 70g of ferric nitrate nonahydrate, 48g of bismuth nitrate pentahydrate, 160g of nickel nitrate hexahydrate, 18g of magnesium nitrate hexahydrate, 1g of potassium nitrate, 1g of cesium nitrate, 30g of chromium nitrate, 60g of cerium nitrate hexahydrate, and 0.05g of ruthenium nitrate, the other catalyst preparation methods were the same as in Example 10. The expression for the active composition of the prepared catalyst is as follows:

[0223] Mo x Bi 0.07x Fe 0.12x Ni 0.5x Mg 0.05x K 0.007x Cs 0.004x Cr (Ⅲ)0.05x Ce (Ⅲ)0.1x Ru 0.0001x O 4x

[0224] The catalyst performance evaluation methods are the same as those in Example 1.

[0225] The active composition and performance evaluation results of the catalyst are shown in Table 1.

[0226] Example 20

[0227] Except for replacing the carrier liquid with 500g of silica sol with a silica content of 30% and 200g of silica sol with a silica content of 41%, the catalyst preparation and molding methods were the same as in Example 10. The active composition of the prepared catalyst was the same as in Example 10.

[0228] The catalyst performance evaluation methods are the same as those in Example 10.

[0229] The composition and performance evaluation results of the catalyst are shown in Table 1.

[0230] Example 21

[0231] Except for replacing the carrier liquid with 300g of silica sol with a silica content of 30% and 400g of silica sol with a silica content of 41%, the catalyst preparation and molding methods were the same as in Example 10. The active composition of the prepared catalyst was the same as in Example 10.

[0232] The catalyst performance evaluation methods are the same as those in Example 10.

[0233] The composition and performance evaluation results of the catalyst are shown in Table 1.

[0234] Example 22

[0235] Except for replacing the carrier liquid with 200g of silica sol with a silica content of 30% and 500g of silica sol with a silica content of 41%, the catalyst preparation and molding methods were the same as in Example 10. The active composition of the prepared catalyst was the same as in Example 10.

[0236] The catalyst performance evaluation methods are the same as those in Example 10.

[0237] The composition and performance evaluation results of the catalyst are shown in Table 1.

[0238] Example 23

[0239] Except for replacing the carrier liquid with 100g of silica sol with a silica content of 30% and 600g of silica sol with a silica content of 41%, the catalyst preparation and molding methods were the same as in Example 10. The active composition of the prepared catalyst was the same as in Example 10.

[0240] The catalyst performance evaluation methods are the same as those in Example 10.

[0241] The composition and performance evaluation results of the catalyst are shown in Table 1.

[0242] Example 24

[0243] Except for replacing the carrier liquid with silica sol consisting entirely of 700g of silica with a silica content of 41%, the catalyst preparation and molding methods were the same as in Example 10. The active composition of the prepared catalyst was the same as in Example 10.

[0244] The catalyst performance evaluation methods are the same as those in Example 10.

[0245] The composition and performance evaluation results of the catalyst are shown in Table 1.

[0246] Example 25

[0247] Except for replacing the carrier liquid with silica sol consisting entirely of 450g of silica with a silica content of 41%, the catalyst preparation and molding methods were the same as in Example 10. The active composition of the prepared catalyst was the same as in Example 10.

[0248] The catalyst performance evaluation methods are the same as those in Example 10.

[0249] The composition and performance evaluation results of the catalyst are shown in Table 1.

[0250] Example 26

[0251] Except for replacing the carrier liquid with silica sol consisting entirely of 600g of silica with a silica content of 41%, the catalyst preparation and molding methods were the same as in Example 10. The active composition of the prepared catalyst was the same as in Example 10.

[0252] The catalyst performance evaluation methods are the same as those in Example 10.

[0253] The composition and performance evaluation results of the catalyst are shown in Table 1.

[0254] Example 25

[0255] Except for replacing the carrier liquid with silica sol consisting entirely of 800g of silica with a silica content of 41%, the catalyst preparation and molding methods were the same as in Example 10. The active composition of the prepared catalyst was the same as in Example 10.

[0256] The catalyst performance evaluation methods are the same as those in Example 10.

[0257] The composition and performance evaluation results of the catalyst are shown in Table 1.

[0258] Example 25

[0259] Except for replacing the carrier liquid with silica sol consisting entirely of 900g of silica with a silica content of 41%, the catalyst preparation and molding methods were the same as in Example 10. The active composition of the prepared catalyst was the same as in Example 10.

[0260] The catalyst performance evaluation methods are the same as those in Example 10.

[0261] The composition and performance evaluation results of the catalyst are shown in Table 1.

[0262] Comparative Example 1

[0263] The active composition of the catalyst provided in Example 5 of Chinese Patent Document CN101168129B is as follows:

[0264] Mo 12 Bi 0.55 Fe1Ni4Mg3Zn 0.5 Mn 0.5 La 0.2 Ce 0.2 Gd 0.1 Na 0.05 Cl 0.05 Al 0.05 K 0.05 Cs 0.2 O x +50% SiO2

[0265] The preparation and evaluation methods of the catalyst are similar to those in the embodiments of this invention.

[0266] The composition and performance evaluation results of the catalyst are shown in Table 1.

[0267] Comparative Example 2

[0268] The active composition of the catalyst provided in Example 5 of Chinese Patent Document CN101168129B is as follows:

[0269] Mo 10 Bi 0.4 Fe 1.3 Ni6Cr 0.8 Ce 0.4 K 0.2 P 0.2 B 0.2 O x +35% SiO2

[0270] The preparation and evaluation methods of the catalyst are similar to those in the embodiments of this invention.

[0271] The composition and performance evaluation results of the catalyst are shown in Table 1.

[0272] Comparative Example 3

[0273] The active composition of the catalyst provided in Example 9 of Chinese Patent Document CN115501882A is as follows:

[0274] Mo 12 Bi 1.5 Fe 2.7 Ni5.5 Mg5K 0.8 Nd 2.45 Tm 0.03 Yb 0.02 O x +50% SiO2

[0275] The preparation and evaluation methods of the catalyst are similar to those in the embodiments of this invention.

[0276] The composition and performance evaluation results of the catalyst are shown in Table 1. Notes: 1. The M value represents the ratio of molybdenum to other metal elements in the catalyst system, reflecting the vacancy structure. The M value ranges from 0.88 to 1.2. When M > 1 and ≤ 1.2, it indicates an excess of molybdenum in the catalyst system, resulting in reduced activity. When M < 1 and ≥ 0.88, it indicates a deficiency of molybdenum, but this molybdenum-deficient structure is conducive to the formation of ion vacancy structures, increasing the lattice oxygen transport rate. 2. The support ratio is the percentage of the total mass of the support in the catalyst (excluding water). The solid content of the support represents the mass percentage of silica in the silica sol composition of the support. 3. The wear index is the percentage of catalyst particles lost between 0 and 5 hours. The wear index is a key indicator of the physical properties of the catalyst of this invention; a lower wear index indicates less catalyst loss in the fluidized bed reactor. Currently, the wear rate of commercially available acrylonitrile catalysts is no more than 4%. The wear index is determined using internationally accepted testing standards.

[0277] As can be seen from Table 1, based on the ratio of different metals in this invention, the formulation composition of the catalyst and the crystal phase structure in the catalyst preparation process are optimized, so that the catalyst prepared by this invention can not only maintain a high yield of trinitrile products for a long time, but also reduce the loss rate of molybdenum-containing substances.

[0278] Based on the above-described preferred embodiments of the present invention, those skilled in the art can make various changes and modifications without departing from the inventive concept, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. An ammonia oxidation catalyst, characterized in that, The active component of the catalyst is composed of the general formula Mo. x Bi a Fe b A c B d C e D f E g F h O y This indicates that in the general formula: Mo, Bi, Fe, and O represent molybdenum, bismuth, iron, and oxygen, respectively. A represents at least one element selected from the combination of nickel, cobalt, manganese, zinc, and cadmium. B represents at least one element selected from the combination of alkaline earth metal elements consisting of magnesium, strontium, and barium; C represents at least one element selected from the combination of alkali metal elements consisting of potassium, rubidium, and cesium; D represents at least one element selected from the combination of tungsten, vanadium, chromium, gallium, germanium, scandium, yttrium, indium, tin, and antimony. E represents at least one element selected arbitrarily from the lanthanides, excluding promethium. F represents at least one element selected from the platinum group elements; a, b, c, d, e, f, g, h, and y represent the number of atoms of the metal elements Bi, Fe, A, B, C, D, E, and F, and oxygen, respectively. x is the number of molybdenum atoms, and x can take any integer value greater than 1, which is used as the baseline value; The value of 'a' is a multiple of x, and the range of multiples of 'a' is 0.03 to 0.

07. b takes the value of a multiple of x, and the multiples of b range from 0.12 to 0.

31. c takes the value of a multiple of x, and the multiple of c ranges from 0.3 to 0.5; d takes the value of a multiple of x, and the multiples of d range from 0.05 to 0.2; e takes the value of a multiple of x, and the multiples of e range from 0.01 to 0.06; f takes the value of a multiple of x, and the multiple of f ranges from 0.01 to 0.05; g takes the value of a multiple of x, and the multiples of g range from 0.01 to 0.1; h takes the value of a multiple of x, and the multiple of h ranges from 0.0001 to 0.001; The value of y is the total number of oxygen atoms required to satisfy the requirements of each element compound in the catalyst.

2. The ammonia oxidation catalyst according to claim 1, characterized in that, The atomic number relationships among the various metallic elements are expressed by the following formula: M = (Number of Mo atoms × 2) / (∑Number of other metallic elements × Valence of the corresponding metallic element) Where M represents the ratio obtained by dividing the product of the valence of molybdate and the number of molybdenum atoms by the sum of the products of the corresponding valences and the number of atoms of the other metal components; The value of M ranges from 0.88 to 1.

2.

3. The ammonia oxidation catalyst according to claim 1, characterized in that, M ranges from 0.93 to 1.

05.

4. The ammonia oxidation catalyst according to claim 1, characterized in that, B represents either magnesium or strontium; C represents either rubidium or cesium; D represents either tungsten or chromium; E represents either lanthanum or cerium; and F represents either platinum or ruthenium.

5. The ammonia oxidation catalyst according to claim 1, characterized in that, The catalyst also includes a support, which is used in an amount of 40-60 wt% of the total mass of the catalyst.

6. A method for preparing an ammonia oxidation catalyst according to any one of claims 1-5, characterized in that, The method includes the following steps: The raw materials of various metal elements constituting the catalyst and the carrier raw materials are mixed in advance to prepare an aqueous slurry. The aqueous slurry is then dehydrated and dried, and the dried product is calcined to finally obtain the catalyst product.

7. The method for preparing the ammonia oxidation catalyst according to claim 5, characterized in that, The raw materials for the metal elements are selected from the following forms of each metal element: oxides or nitrates, ammonium salts, and hydroxides.

9. The method for preparing the ammonia oxidation catalyst according to claim 5, characterized in that: The roasting temperature is 550-650℃, and the roasting time is 2-4 hours.

10. The application of an ammonia oxidation catalyst as described in any one of claims 1-5, characterized in that: The catalyst is used in the ammonia oxidation catalytic reaction of propylene, ammonia and oxygen. Under certain reaction temperature and reaction pressure, propylene, ammonia and oxygen-containing gas react in a fluidized bed reactor packed with the catalyst to convert propylene into acrylonitrile, acetonitrile, hydrogen cyanide or other related products.

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