Oxidation catalysts, methods of making and using the same, and methods of propylene oxidation

Abstract

This invention relates to the field of catalyst technology, specifically an oxidation catalyst whose components are represented by the general formula: MoBi. a Fe b Co c X d Y e Z f O j The catalyst has a hollow thin-shell structure and an average pore size greater than 70 nm. The oxidation catalyst of this invention is used for the oxidation of olefins (e.g., propylene) to prepare alkenals and / or olefinic acids (e.g., acrolein and / or acrylic acid), and has CO2 content. x It has the advantages of low yield and high product selectivity.

Description

Technical Field

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

[0002] The selective oxidation of olefins to produce unsaturated acids is an important chemical process. Industrially, olefins are typically oxidized first to obtain unsaturated aldehydes, which are then oxidized to unsaturated acids. This process usually employs a two-stage production method, using two reactors and two catalysts under different reaction conditions. The first stage reaction mainly produces acrolein, with approximately 20% acrylic acid. The active component of the catalyst is a complex Mo / Bi composite oxide system. Catalyst improvements primarily focus on enhancing activity and stability. For example, adding transition metals to the active component can improve activity and increase product yield; adding rare earth elements can improve redox capabilities; and adding elements such as Fe, Co, and Ni can inhibit Mo sublimation, stabilize the active component, and extend catalyst lifespan. Furthermore, due to the intense exothermic reaction, controlling the catalyst bed temperature is crucial. Hot spots not only degrade reaction performance but also shorten catalyst lifespan and affect the stable operation of the plant.

[0003] It is generally believed that in the first step of the propylene oxidation reaction to produce acrolein, the olefin is adsorbed on the catalyst surface, an α-H is removed by a metal oxide, forming a free radical intermediate, which generates the product through oxygen-nitrogen intercalation. In this process, the catalyst undergoes a redox cycle, losing the oxygen atom that participated in the intercalation reaction, being reduced, and then re-oxidized by oxygen in the reaction gas, replenishing the active site oxygen atom through oxygen migration. Therefore, the catalyst is required to have good oxygen migration energy to maintain the catalyst structure and redox balance. Transition metal composite oxides such as Mo, V, Bi, Te, Nb, and Fe are generally used (Catalysis Today 49 (1999) 141-153).

[0004] US4224187 and US4248803 propose improving olefin conversion and target product yield by modifying the composition and dosage ratio of catalysts and catalyst preparation methods. However, their application in the selective oxidation of isobutylene suffers from low reaction selectivity. While the isobutylene conversion is as high as 99%, the overall yield of methacrolein and methacrylic acid is only 73.6%.

[0005] US6268529 discloses a propylene oxidation catalyst with a propylene conversion of 98.1%, an acrolein yield of 65.3%, an acrylic acid yield of 20.8%, and a total yield of 86.1% for acrolein and acrylic acid.

[0006] CN1564709A improves catalyst performance by adding an organic carboxylic acid to overcome the catalyst inhomogeneity caused by stratification between metal salts during the co-precipitation process. It is used for the selective oxidation of propylene, achieving a propylene conversion of up to 98.12%, a selectivity of up to 82.53% for acrolein, and a total yield of 91.05% for acrolein and acrylic acid.

[0007] CN1210511A, CN1283604A, and CN1314331A achieve the goal of controlling reaction hotspots and extending catalyst stability by configuring multiple catalyst layers with gradually increasing reactivity along the reactor axis from the reactant gas inlet to the outlet. To control the exothermic reaction, it is necessary to control the byproduct CO. x The amount generated, because propylene produces CO. x The heat released is several times that of the formation of acrolein and acrylic acid or other organic byproducts. Therefore, CO x The higher the temperature, the greater the heat, and the higher the temperature of the hot spot, the worse the selectivity. Summary of the Invention

[0008] The purpose of this invention is to overcome the limitations of existing oxidation catalysts for CO. x To address the problems of high yield and low product selectivity, this invention provides an oxidation catalyst, its preparation method, and its application, as well as a method for propylene oxidation. This catalyst is used for olefin oxidation, such as the propylene oxidation to prepare acrolein and acrylic acid, and exhibits CO2 efficiency. x It has the advantages of low yield and high product selectivity.

[0009] To achieve the above objectives, a first aspect of the present invention provides an oxidation catalyst, the components of which are represented by the general formula: MoBi a Fe b Co c X d Y e Z f O j Where X is at least one selected from Mg, Ca, Cu, Zn, and Ba; Y is at least one selected from La, Ce, and Sm; Z is at least one selected from K, Rb, Na, Li, and Cs; a is the molar ratio of Bi to Mo, with a value of 0.1-0.5; b is the molar ratio of Fe to Mo, with a value of 0.1-0.5; c is the molar ratio of Co to Mo, with a value of 0.1-1.5; d is the molar ratio of X to Mo, with a value of 0.1-0.5; e is the molar ratio of Y to Mo, with a value of 0.1-0.5; f is the molar ratio of Z to Mo, with a value of 0.01-0.06; and j is the total number of oxygen atoms required to satisfy the valence of other elements.

[0010] The catalyst has a hollow thin-shell structure and an average pore size greater than 70 nm.

[0011] A second aspect of the present invention provides a method for preparing the oxidation catalyst of the present invention, the method comprising:

[0012] (1) Dissolve the Mo compound and the Z compound in water to obtain a first solution; dissolve the Bi compound, the Fe compound, the Co compound, the Y compound and the X compound in water to form a second solution; mix the first solution and the second solution, concentrate and dry to obtain a solid; pre-calcine the solid and grind it into a fine powder with a particle size of less than 15 micrometers;

[0013] (2) Disperse the fine powder in a solvent to obtain a slurry, and then calcine the slurry after spray drying to obtain the catalyst; the solid content of the slurry is 15-35% by weight; the spray drying conditions include: hot air inlet temperature of 400-600℃.

[0014] A third aspect of the present invention provides the application of the described oxidation catalyst in the oxidation of olefins to prepare enaldehydes and / or olefinic acids.

[0015] A fourth aspect of the present invention provides a method for propylene oxidation, the method comprising: contacting a propylene-containing feed gas and an oxygen-containing oxidizing gas with a catalyst to prepare acrolein and / or acrylic acid; wherein the catalyst is the oxidation catalyst described in the present invention.

[0016] This invention employs a process of first drying and pre-calcining, then grinding, and finally preparing the fine powder into a slurry. The slurry is then spray-dried at a relatively high hot air inlet temperature and with an appropriate reduction in solid content to obtain hollow thin-shell microsphere catalysts with large pore sizes.

[0017] The oxidation catalyst of this invention has a hollow thin-shell structure, and according to a preferred embodiment of the invention, the catalyst has a large pore size. The oxidation catalyst of this invention is used for the oxidation of olefins (e.g., propylene) to prepare alkenals and / or olefinic acids (e.g., acrolein and / or acrylic acid), and has CO2 content. x It has the advantages of low yield and high product selectivity.

[0018] It is speculated that the hollow thin-shell structure and large pore size of the catalyst increase the diffusion rate of reactants and products, significantly shorten the diffusion path, and facilitate the removal of heat from the catalyst, thereby effectively reducing the occurrence of deep oxidation reactions and lowering CO2 levels. x This improves the yield, thereby reducing the generation of reaction heat, effectively controlling the reaction hot spot temperature, and improving the selectivity of the target product. Attached Figure Description

[0019] Figure 1 This is a scanning electron microscope (SEM) image of the oxidation catalyst prepared in Example 1;

[0020] Figure 2 This is a scanning electron microscope (SEM) image of the oxidation catalyst prepared in Comparative Example 1. Detailed Implementation

[0021] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0022] The first aspect of this invention provides an oxidation catalyst, the components of which are represented by the general formula: MoBi a Fe b Co c X d Y e Z f O j Where X is at least one selected from Mg, Ca, Cu, Zn, and Ba; Y is at least one selected from La, Ce, and Sm; Z is at least one selected from K, Rb, Na, Li, and Cs; a is the molar ratio of Bi to Mo, with a value of 0.1-0.5; b is the molar ratio of Fe to Mo, with a value of 0.1-0.5; c is the molar ratio of Co to Mo, with a value of 0.1-1.5; d is the molar ratio of X to Mo, with a value of 0.1-0.5; e is the molar ratio of Y to Mo, with a value of 0.1-0.5; f is the molar ratio of Z to Mo, with a value of 0.01-0.06; and j is the total number of oxygen atoms required to satisfy the valence of other elements.

[0023] The catalyst has a hollow thin-shell structure and an average pore size greater than 70 nm.

[0024] According to a preferred embodiment of the present invention, the catalyst has a diameter of 5-150 micrometers and a catalyst shell thickness of 0.5-15 micrometers.

[0025] In this invention, the catalyst diameter is determined by a laser particle size analyzer, and the average particle size D[4,3] is used. The shell thickness is measured according to the scale bar of the electron microscope image.

[0026] According to a preferred embodiment of the present invention, the oxidation catalyst has an average pore size of 85-200 nm.

[0027] In this invention, the average pore size of the catalyst is measured by the BET method.

[0028] According to a preferred embodiment of the present invention, X is selected from at least two of Mg, Ca, Cu and Zn; preferably, the molar ratio of the two is 0.5-2:1.

[0029] For example, when X is both Mg and Cu, the preferred molar ratio of Mg to Cu is 0.5-2:1.

[0030] According to a preferred embodiment of the present invention, Y is La and Ce, and preferably, the molar ratio of La to Ce is 0.5-3:1.

[0031] According to a preferred embodiment of the present invention, the value of a is 0.2-0.4.

[0032] According to a preferred embodiment of the present invention, the value of b is 0.2-0.4.

[0033] According to a preferred embodiment of the present invention, the value of c is 0.3-1.0.

[0034] According to a preferred embodiment of the present invention, the value of d is 0.2-0.4.

[0035] According to a preferred embodiment of the present invention, the value of e is 0.2-0.4.

[0036] According to a preferred embodiment of the present invention, the value of f is 0.02-0.04.

[0037] A second aspect of the present invention provides a method for preparing the oxidation catalyst of the present invention, the method comprising:

[0038] (1) Dissolve the Mo compound and the Z compound in water to obtain a first solution; dissolve the Bi compound, the Fe compound, the Co compound, the Y compound and the X compound in water to form a second solution; mix the first solution and the second solution, concentrate and dry to obtain a solid; pre-calcine the solid and grind it into a fine powder with a particle size of less than 15 micrometers;

[0039] (2) The fine powder is dispersed in a solvent to obtain a slurry. The slurry is then spray-dried and calcined to obtain the catalyst. The solid content of the slurry is 15-35% by weight. The spray drying conditions include a hot air inlet temperature of 400-600℃. This invention employs a method of first drying and pre-calcining, then grinding, and finally preparing the fine powder into a slurry. The slurry is then spray-dried at a relatively high hot air inlet temperature and with an appropriate reduction in the solid content of the slurry to obtain a catalyst with a hollow thin-shell structure and a large pore size.

[0040] In this invention, there is no limitation on the order of preparation of the first solution and the second solution.

[0041] According to a preferred embodiment of the present invention, the solid content of the slurry is 20-30% by weight.

[0042] According to a preferred embodiment of the present invention, the spray drying conditions include a hot air inlet temperature of 450-550°C.

[0043] In this invention, the conditions for obtaining solids by concentration and drying in step (1) are available in a wide range. According to a preferred embodiment of this invention, the concentration conditions include a temperature of 60-80°C; the drying conditions include a temperature of 100-150°C; and the concentration and drying times can be reasonably adjusted according to actual needs.

[0044] In this invention, the range of selectable pre-firing conditions in step (1) is relatively wide. According to a preferred embodiment of this invention, the pre-firing conditions include: a temperature of 180-250℃; the pre-firing time can be reasonably adjusted according to actual needs, preferably, the pre-firing time is 1-3h.

[0045] In this invention, in step (2), the solvent is not particularly limited and can be a conventional solvent in the art, such as water; the method of dispersing fine powder into the solvent to obtain a slurry is not particularly limited, for example, a slurry can be obtained by adding an appropriate amount of water to the fine powder and then shearing and mixing it at high speed.

[0046] In this invention, the range of roasting conditions that can be selected in step (2) is relatively wide. According to a preferred embodiment of this invention, the roasting conditions include: a temperature of 400-650℃; the roasting time can be reasonably adjusted according to actual needs, preferably 1-12h.

[0047] According to some embodiments of the preparation method described in this invention, the calcination conditions include a temperature of 400-650°C. For example, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, and any value between them.

[0048] According to some embodiments of the preparation method described in this invention, the calcination conditions include a time of 1 to 12 hours. For example, 1 hour, 3 hours, 5 hours, 7 hours, 9 hours, 10 hours, 12 hours, and any values ​​between them.

[0049] According to a preferred embodiment of the present invention, the calcination atmosphere is an inert atmosphere and / or an atmosphere containing O2. However, from an economic point of view, the calcination atmosphere is preferably air. Unless otherwise specified, the calcination atmosphere in the present invention is always air.

[0050] According to a preferred embodiment of the present invention, the slurry is a solution, a suspension, or a mixture of a solution and a suspension.

[0051] According to a preferred embodiment of the present invention, the amount of water used in the first solution and the second solution has a wide range of selection, with the aim of fully dissolving the compound.

[0052] According to a preferred embodiment of the present invention, the Mo compound, Y compound, Bi compound, Fe compound, Co compound, X compound and Z compound may be selected from nitrates, ammonium salts, sulfates, oxides, hydroxides, chlorides, acetates and the like.

[0053] According to a preferred embodiment of the present invention, the Mo compound may be selected from, but is not limited to, one or more of: ammonium molybdate, molybdenum trioxide, molybdenum nitrate, molybdic acid, and sodium molybdate.

[0054] According to a preferred embodiment of the present invention, the Bi compound may be selected from, but is not limited to, one or more of bismuth nitrate, bismuth trioxide, bismuth sulfate, bismuth chloride, and bismuth acetate.

[0055] According to a preferred embodiment of the present invention, the Fe compound may be selected from, but is not limited to, one or more of: ferric nitrate, ferric sulfate, ferric chloride, ferric oxide, and ferrous sulfate.

[0056] According to a preferred embodiment of the present invention, the Co compound may be selected from, but is not limited to, one or more of cobalt nitrate, cobalt sulfate, and cobalt oxide.

[0057] According to a preferred embodiment of the present invention, the X compound may be selected from, but is not limited to, one or more of: magnesium nitrate, magnesium sulfate, magnesium chloride, magnesium oxide, magnesium acetate, barium nitrate, calcium nitrate, copper nitrate, zinc nitrate, and manganese nitrate.

[0058] According to a preferred embodiment of the present invention, the Y compound may be selected from, but is not limited to, one or more of: lanthanum nitrate, cerium nitrate, cerium sulfate, cerium perchlorate, cerium dioxide, cerium acetate, and samarium nitrate.

[0059] According to a preferred embodiment of the present invention, the Z compound may be selected from, but is not limited to, one or more of potassium nitrate, rubidium nitrate, sodium nitrate, sodium sulfate, sodium chloride, sodium acetate, sodium hydroxide, lithium nitrate, and cesium nitrate.

[0060] A third aspect of this invention provides the application of the described oxidation catalyst in the oxidation of olefins to prepare enaldehydes and / or acrylates. The oxidation catalyst of this invention is used for the oxidation of olefins (e.g., propylene) to prepare enaldehydes and / or acrylates (e.g., acrolein and / or acrylic acid), and has CO2 content. x It has the advantages of low yield and high product selectivity.

[0061] A fourth aspect of this invention provides a method for preparing acrolein, the method comprising: contacting a propylene-containing feed gas and an oxygen-containing oxidizing gas with a catalyst to prepare acrolein and / or acrylic acid; wherein the catalyst is the oxidation catalyst described in this invention. The oxidation catalyst of this invention is used for the oxidation of olefins (e.g., propylene) to prepare alkenes and / or olefinic acids (e.g., acrolein and / or acrylic acid), and has CO2 content. x It has the advantages of low yield and high product selectivity.

[0062] According to a preferred embodiment of the present invention, the contact conditions include a temperature of 100-500°C, preferably 350-420°C.

[0063] According to a preferred embodiment of the present invention, the contact conditions include a pressure of 0.01-0.05 MPa, wherein the pressure is gauge pressure.

[0064] According to a preferred embodiment of the present invention, the contact conditions include: the volumetric hourly space velocity of the feed gas is 800-1200 mL / g·h.

[0065] According to a preferred embodiment of the present invention, the contact conditions include: propylene: oxygen-containing oxidizing gas = 1:(6-8) by volume.

[0066] According to a preferred embodiment of the present invention, in order to make the reaction more stable and controllable, the feed gas also contains a diluting gaseous material; by volume ratio, propylene: diluting gaseous material = 1:(0.5-5).

[0067] According to a preferred embodiment of the present invention, the dilutive gaseous material is water vapor.

[0068] According to a preferred embodiment of the present invention, the oxygen-containing oxidizing gas can be pure oxygen or oxygen-enriched gas, but air is preferred from an economic point of view.

[0069] To make the present invention easier to understand, the present invention will be described in detail below with reference to embodiments. These embodiments are for illustrative purposes only and are not limited to the scope of application of the present invention.

[0070] In the following examples, the catalyst evaluation conditions are as follows:

[0071] Reactor: Fixed-bed single-tube reactor, inner diameter 18 mm, reactor length 200 mm

[0072] Catalyst: 5 grams

[0073] Reaction temperature: 380℃

[0074] Reaction pressure: 0.02 MPa (gauge pressure)

[0075] Propylene:Air (feedstock molar ratio) = 1:7.1

[0076] Propylene:water vapor = 1:1.9

[0077] Feed gas volumetric hourly space velocity: 1000 mL / g·h

[0078] The reaction products were absorbed with dilute acid at 0°C and analyzed by gas chromatography (Agilent 7890A). The carbon balance was calculated, and data were considered valid when the carbon balance was between (95% and 105%).

[0079] The definitions of propylene conversion, product yield, and selectivity are as follows:

[0080]

[0081]

[0082]

[0083] Example 1

[0084] (1) Weigh out 1 mol of ammonium molybdate and 0.02 mol of potassium hydroxide (K) and dissolve them in 200 g of water to obtain the first solution. Weigh out 0.3 mol of bismuth nitrate (Bi), 0.4 mol of ferric nitrate (Fe), 0.4 mol of magnesium nitrate (Mg), 0.3 mol of cobalt nitrate (Co), and 0.4 mol of lanthanum nitrate (La) and dissolve them in 200 g of water to obtain the second solution. Mix the first and second solutions, evaporate and concentrate at 70 °C, pre-calcine at 200 °C for 2 hours, grind and sieve through a 1000 mesh sieve to obtain a fine powder.

[0085] (2) Add an appropriate amount of water to the fine powder to adjust the solid content of the slurry to 25%, and shear and disperse for 30 minutes to obtain the slurry. Adjust the hot air inlet temperature of the sprayer to 450℃ and spray dry. Then calcine in air at 550℃ for 2 hours to obtain the catalyst MoBi. 0.3 Fe 0.4 Co 0.3 Mg 0.4 La 0.4 K 0.02 O j .

[0086] The obtained catalyst was tested and evaluated, and the results are shown in Table 1.

[0087] SEM image of the catalyst as shown Figure 1 As shown, the catalyst has a hollow thin-shell structure, with an average particle size of 72 μm and an average shell thickness of 5.3 μm; the average pore size of the catalyst is 106 nm.

[0088] Example 2

[0089] (1) Weigh out 1 mol of ammonium molybdate (Mo), 0.02 mol of sodium hydroxide (Na), and 0.04 mol of potassium hydroxide (K) and dissolve them in 200 g of water to obtain the first solution. Weigh out 0.1 mol of bismuth nitrate (Bi), 0.5 mol of ferric nitrate (Fe), 0.1 mol of calcium nitrate (Ca), 1.5 mol of cobalt nitrate (Co), and 0.1 mol of cerium nitrate (Ce) and dissolve them in 200 g of water to obtain the second solution. Mix the first and second solutions, evaporate and concentrate at 70 °C, pre-calcine at 200 °C for 2 hours, grind and sieve through a 1000 mesh sieve to obtain a fine powder.

[0090] (2) Add an appropriate amount of water to the fine powder to adjust the solid content of the slurry to 25%, and shear and disperse for 30 minutes to obtain the slurry. Adjust the hot air inlet temperature of the sprayer to 450℃ and spray dry. Then calcine in air at 550℃ for 2 hours to obtain the catalyst MoBi. 0.1 Fe 0.5 Co 1.5 Ca 0.1 La 0.1 Na 0.02 K 0.04 O j .

[0091] SEM images of the catalyst and Figure 1 Similarly, the catalyst has a hollow thin-shell structure with an average particle size of 74 μm and an average shell thickness of 4.9 μm; the average pore size of the catalyst is 95 nm.

[0092] The obtained catalyst was evaluated, and the results are shown in Table 1.

[0093] Example 3

[0094] (1) Weigh out 1 mol of ammonium molybdate (Mo) and 0.01 mol of cesium hydroxide (Cs) and dissolve them in 200 g of water to obtain the first solution. Weigh out 0.5 mol of bismuth nitrate (Bi), 0.1 mol of ferric nitrate (Fe), 0.1 mol of calcium nitrate (Ca), 0.4 mol of copper nitrate (Cu), 0.1 mol of cobalt nitrate (Co), 0.4 mol of cerium nitrate (Ce), and 0.1 mol of samarium nitrate (Sm) and dissolve them in 200 g of water to obtain the second solution. Mix the first and second solutions, evaporate and concentrate at 70 °C, pre-calcine at 200 °C for 2 hours, grind and sieve through a 1000 mesh sieve to obtain a fine powder.

[0095] (2) Add an appropriate amount of water to the fine powder to adjust the solid content of the slurry to 25%, and shear and disperse for 30 minutes to obtain the slurry. Adjust the hot air inlet temperature of the sprayer to 450℃ and spray dry. Then calcine in air at 550℃ for 2 hours to obtain the catalyst MoBi. 0.5 Fe 0.1 Co 0.1 Ca 0.1 Cu 0.4 La0.4 Sm 0.1 Cs 0.01 O j .

[0096] SEM images of the catalyst and Figure 1 Similarly, the catalyst has a hollow thin-shell structure with an average particle size of 75 μm and an average shell thickness of 5.1 μm; the average pore size of the catalyst is 89 nm.

[0097] The obtained catalyst was evaluated, and the results are shown in Table 1.

[0098] Example 4

[0099] (1) Weigh out 1 mol of ammonium molybdate and 0.02 mol of potassium hydroxide (K) and dissolve them in 200 g of water to obtain the first solution. Weigh out 0.3 mol of bismuth nitrate (Bi), 0.4 mol of ferric nitrate (Fe), 0.2 mol of magnesium nitrate (Mg), 0.2 mol of copper nitrate (Cu), 0.3 mol of cobalt nitrate (Co), and 0.4 mol of lanthanum nitrate (La) and dissolve them in 200 g of water to obtain the second solution. Mix the first and second solutions, evaporate and concentrate at 70 °C, pre-calcine at 200 °C for 2 hours, grind and sieve through a 1000 mesh sieve to obtain a fine powder.

[0100] (2) Add an appropriate amount of water to the fine powder to adjust the solid content of the slurry to 25%, and shear and disperse for 30 minutes to obtain the slurry. Adjust the hot air inlet temperature of the sprayer to 450℃ and spray dry. Then calcine in air at 550℃ for 2 hours to obtain the catalyst MoBi. 0.3 Fe 0.4 Co 0.3 Mg 0.2 Cu 0.2 La 0.4 K 0.02 O j .

[0101] The obtained catalyst was tested and evaluated, and the results are shown in Table 1.

[0102] SEM images of the catalyst and Figure 1 Similarly, this indicates that the catalyst has a hollow thin-shell structure, with an average particle size of 70 μm, an average shell thickness of 5.5 μm, and an average pore size of 98 nm.

[0103] Example 5

[0104] (1) Weigh out 1 mol of ammonium molybdate and 0.02 mol of potassium hydroxide (K) and dissolve them in 200 g of water to obtain the first solution. Weigh out 0.3 mol of bismuth nitrate (Bi), 0.4 mol of ferric nitrate (Fe), 0.4 mol of magnesium nitrate (Mg), 0.3 mol of cobalt nitrate (Co), 0.2 mol of lanthanum nitrate (La), and 0.2 mol of cerium nitrate (Ce) and dissolve them in 200 g of water to obtain the second solution. Mix the first and second solutions, evaporate and concentrate at 70 °C, pre-calcine at 200 °C for 2 hours, grind and sieve through a 1000 mesh sieve to obtain a fine powder.

[0105] (2) Add an appropriate amount of water to the fine powder to adjust the solid content of the slurry to 25%, and shear and disperse for 30 minutes to obtain the slurry. Adjust the hot air inlet temperature of the sprayer to 450℃ and spray dry. Then calcine in air at 550℃ for 2 hours to obtain the catalyst MoBi. 0.3 Fe 0.4 Co 0.3 Mg 0.4 La 0.2 Ce 0.2 K 0.02 O j .

[0106] The obtained catalyst was tested and evaluated, and the results are shown in Table 1.

[0107] SEM images of the catalyst and Figure 1 Similarly, this indicates that the catalyst has a hollow thin-shell structure, with a diameter of 77 μm and a shell thickness of 5.4 μm; the average pore size of the catalyst is 102 nm.

[0108] Example 6

[0109] (1) Weigh out 1 mol of ammonium molybdate and 0.02 mol of potassium hydroxide (K) and dissolve them in 200 g of water to obtain the first solution. Weigh out 0.3 mol of bismuth nitrate (Bi), 0.4 mol of ferric nitrate (Fe), 0.2 mol of magnesium nitrate (Mg), 0.2 mol of copper nitrate (Cu), 0.3 mol of cobalt nitrate (Co), 0.2 mol of lanthanum nitrate (La), and 0.2 mol of cerium nitrate (Ce) and dissolve them in 200 g of water to obtain the second solution. Mix the first and second solutions, evaporate and concentrate at 70 °C, pre-calcine at 200 °C for 2 hours, grind and sieve through a 1000 mesh sieve to obtain a fine powder.

[0110] (2) Add an appropriate amount of water to the fine powder to adjust the solid content of the slurry to 25%, and shear and disperse for 30 minutes to obtain the slurry. Adjust the hot air inlet temperature of the sprayer to 450℃ and spray dry. Then calcine in air at 550℃ for 2 hours to obtain the catalyst MoBi. 0.3 Fe 0.4 Co 0.3 Mg 0.2 Cu 0.2 La0.2 Ce 0.2 K 0.02 O j .

[0111] The obtained catalyst was tested and evaluated, and the results are shown in Table 1.

[0112] SEM images of the catalyst and Figure 1 Similarly, this indicates that the catalyst has a hollow thin-shell structure, with an average particle size of 71 μm, an average shell thickness of 5.2 μm, and an average pore size of 105 nm.

[0113] Comparative Example 1

[0114] (1) Weigh out 1 mol of ammonium molybdate and 0.02 mol of potassium hydroxide (K) and dissolve them in 200 g of water to obtain the first solution. Weigh out 0.3 mol of bismuth nitrate (Bi), 0.4 mol of ferric nitrate (Fe), 0.4 mol of magnesium nitrate (Mg), 0.3 mol of cobalt nitrate (Co), and 0.4 mol of lanthanum nitrate (La) and dissolve them in 200 g of water to obtain the second solution. Mix the first and second solutions, evaporate and concentrate at 70 °C, pre-calcine at 200 °C for 2 hours, grind and sieve through a 1000 mesh sieve to obtain a fine powder.

[0115] (2) Add an appropriate amount of water to the fine powder to adjust the solid content of the slurry to 50%, and shear and disperse for 30 minutes to obtain the slurry. Adjust the hot air inlet temperature of the sprayer to 450℃ and spray dry. Then calcine in air at 550℃ for 2 hours to obtain the catalyst MoBi. 0.3 Fe 0.4 Co 0.3 Mg 0.4 La 0.4 K 0.02 O j .

[0116] The obtained catalyst was evaluated, and the results are shown in Table 1.

[0117] SEM image of the catalyst as follows Figure 2 As shown, the catalyst has a solid structure, and the average diameter of the catalyst microspheres is 74 μm.

[0118] Comparative Example 2

[0119] A first solution was obtained by dissolving 1 mol of ammonium molybdate (Mo) and 0.02 mol of potassium hydroxide (K) in 200 g of water. A second solution was obtained by dissolving 0.3 mol of bismuth nitrate (Bi), 0.4 mol of ferric nitrate (Fe), 0.4 mol of magnesium nitrate (Mg), 0.3 mol of cobalt nitrate (Co), and 0.4 mol of lanthanum nitrate (La) in 200 g of water. The first and second solutions were mixed, and an appropriate amount of water was added to adjust the slurry solid content to 25%. The mixture was sheared and dispersed for 30 minutes to obtain a slurry. The hot air inlet temperature of the sprayer was adjusted to 450°C, and the mixture was spray-dried. The slurry was then calcined in air at 550°C for 2 hours to obtain the catalyst MoBi. 0.3 Fe 0.4 Co 0.3 Mg 0. 4La 0.4 K 0.02 O j .

[0120] The obtained catalyst was tested and evaluated, and the results are shown in Table 1.

[0121] SEM images of the catalyst and Figure 1 Similarly, this indicates that the catalyst has a hollow thin-shell structure, with a catalyst diameter of 73 μm, a shell thickness of 4.8 μm, and an average pore size of 32 nm.

[0122] Comparative Example 3

[0123] A first solution was obtained by dissolving 1 mol of ammonium molybdate (Mo) and 0.02 mol of potassium hydroxide (K) in 200 g of water. A second solution was obtained by dissolving 0.3 mol of bismuth nitrate (Bi), 0.4 mol of ferric nitrate (Fe), 0.4 mol of magnesium nitrate (Mg), 0.3 mol of cobalt nitrate (Co), and 0.4 mol of lanthanum nitrate (La) in 200 g of water. The first and second solutions were mixed and sheared and dispersed for 30 minutes to obtain a slurry. After concentration at 80 °C, the slurry was dried at 120 °C for 8 hours. Finally, it was calcined at 550 °C in air for 2 hours to obtain the catalyst MoBi. 0.3 Fe 0.4 Co 0.3 Mg 0.4 La 0.4 K 0.02 O j The 5-150 micrometer fraction was crushed and screened, and the average diameter of the catalyst was 75 μm.

[0124] The obtained catalyst was evaluated, and the results are shown in Table 1.

[0125] Table 1

[0126]

[0127] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An oxidation catalyst, characterized in that, The general formula for the composition of this catalyst is: MoBi a Fe b Co c X d Y e Z f O j Where X is at least one selected from Mg, Ca, Cu, Zn, and Ba; Y is at least one selected from La, Ce, and Sm; Z is at least one selected from K, Rb, Na, Li, and Cs; a is the molar ratio of Bi to Mo, with a value of 0.1-0.5; b is the molar ratio of Fe to Mo, with a value of 0.1-0.5; c is the molar ratio of Co to Mo, with a value of 0.1-1.5; d is the molar ratio of X to Mo, with a value of 0.1-0.5; e is the molar ratio of Y to Mo, with a value of 0.1-0.5; f is the molar ratio of Z to Mo, with a value of 0.01-0.06; and j is the total number of oxygen atoms required to satisfy the valence of other elements. The catalyst has a hollow thin-shell structure and an average pore size of 85-200 nm; the preparation method of the oxidation catalyst includes: (1) Dissolve the Mo compound and the Z compound in water to obtain a first solution; dissolve the Bi compound, the Fe compound, the Co compound, the Y compound and the X compound in water to form a second solution; mix the first solution and the second solution, concentrate and dry to obtain a solid; after pre-calcining the solid, grind it into a fine powder with a particle size of less than 15 micrometers; the pre-calcining conditions include a temperature of 180-250℃; (2) Disperse the fine powder into a solvent to obtain a slurry, and then calcine the slurry after spray drying to obtain the catalyst; the solid content of the slurry is 15-35% by weight; the spray drying conditions include: the hot air inlet temperature is 400-600℃.

2. The oxidation catalyst according to claim 1, wherein, The catalyst diameter is 5-150 micrometers, and the catalyst shell thickness is 0.5-15 micrometers; and / or X is selected from at least two of Mg, Ca, Cu, and Zn; and / or Y represents La and Ce.

3. The oxidation catalyst according to claim 1 or 2, wherein, The value of a ranges from 0.2 to 0.4; and / or The value of b is between 0.2 and 0.4; and / or The value of c ranges from 0.3 to 1.0; and / or The value of d is 0.2-0.4; and / or The value of e is between 0.2 and 0.4; and / or The value of f ranges from 0.02 to 0.

04.

4. The oxidation catalyst according to claim 1, wherein, In step (2), the solid content of the slurry is 20-30% by weight; and / or The inlet temperature of the hot air is 450-550℃.

5. The oxidation catalyst according to claim 1 or 4, wherein, In step (1), the concentration conditions include: a temperature of 60-80℃; and / or Drying conditions include: a temperature of 100-150℃; and / or Pre-firing conditions include: a pre-firing time of 1-3 hours; and / or In step (2), the calcination conditions include: a temperature of 400~650℃; and / or a time of 1~12h.

6. The use of the oxidation catalyst according to any one of claims 1-5 in the oxidation of olefins to prepare alkenal and / or olefinic acids.

7. A method for propylene oxidation, characterized in that, The method includes: contacting a propylene-containing feed gas and an oxygen-containing oxidizing gas with a catalyst to prepare acrolein and / or acrylic acid; the catalyst includes the oxidation catalyst according to any one of claims 1-5.

8. The method according to claim 7, wherein, Exposure conditions include: Temperature range: 100-500℃; The pressure is 0.01-0.05 MPa, and the pressure is gauge pressure. The volumetric hourly space velocity (VHSV) of the feed gas is 800-1200 mL / g•h; and / or By volume ratio, propylene : oxygen-containing oxidizing gas = 1 : (6-8).

9. The method according to claim 8, wherein, Contact conditions include a temperature of 350-420℃.

10. The method according to claim 7 or 8, wherein, The feed gas also contains diluent gaseous materials; by volume ratio, propylene: diluent gaseous materials = 1:(0.5-5); and / or The oxygen-containing oxidizing gas is one or more of oxygen and air.

11. The method according to claim 10, wherein, The diluting gaseous material is water vapor; and / or The oxygen-containing oxidizing gas is air.

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