Oxidation catalyst, preparation method and application thereof, and propylene oxidation method

Abstract

The invention relates to the technical field of catalysts, in particular to an oxidation catalyst, the component general formula of the catalyst is shown as MoBiaFebCocXdYeZfOj, the catalyst is of a hollow thin-shell structure, and the average pore size of the catalyst is larger than 70 nm. The oxidation catalyst is used for preparing olefine aldehyde and / or olefine acid (such as acrolein and / or acrylic acid) through olefin (such as propylene) oxidation, and has the advantages of low COx yield and high product selectivity.

Description

Technical Field

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

[0002] The selective oxidation of olefins to prepare unsaturated acids is an important chemical process. In industry, olefins are usually oxidized to obtain unsaturated aldehydes, and then the unsaturated aldehydes are oxidized to obtain unsaturated acids. This process usually adopts two-stage production, using two reactors and two catalysts under different reaction conditions. One stage of reaction mainly produces acrolein, and there is also about 20% acrylic acid. The active components of the catalyst are a complex Mo and Bi composite oxide system. The improvement of the catalyst is mainly carried out from the aspects of catalyst activity and stability, such as adding transition metals to the active components to improve activity and increase the single yield of the product; adding rare earth elements to improve redox ability; adding Fe, Co, Ni and other elements to inhibit the sublimation of Mo, stabilize the active components of the catalyst, and increase the service life of the catalyst. In addition, due to the violent exothermic phenomenon in the reaction, it is very important to control the reaction temperature of the catalyst bed. The formation of hot spots not only makes the reaction performance worse, but also shortens the service life of the catalyst and affects the stable operation of the device.

[0003] It is generally believed that in the first step of the reaction of propylene oxidation to produce acrolein, the olefin is adsorbed on the catalyst surface, an α-H is removed by the metal oxide, and a free radical intermediate is formed, which is then inserted into the active nitrogen to generate the product. In this process, the catalyst undergoes a redox cycle, in which it loses the oxygen atom involved in the insertion reaction, is reduced, and then is reoxidized by the oxygen in the reaction gas, and the active oxygen atom is supplemented by the migration of oxygen. Therefore, the catalyst is required to have good oxygen migration energy in order to maintain the catalyst structure and redox balance. Generally, transition metal composite oxides such as Mo, V, Bi, Te, Nb, and Fe are used (Catalysis Today 49 (1999) 141-153).

[0004] US4224187 and US4248803 proposed to improve the olefin conversion rate and target product yield by improving the catalyst composition and their usage ratio and catalyst preparation method. For the selective oxidation of isobutylene, there is a problem of low reaction selectivity. The isobutylene conversion rate is as high as 99%, but the total yield of methacrolein and methacrylic acid is only 73.6%.

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

[0006] CN1564709A improves catalyst performance by adding organic carboxylic acid to overcome the catalyst unevenness caused by the stratification of metal salts during the catalyst preparation coprecipitation process. It is used for the selective oxidation reaction of propylene, wherein the propylene conversion rate is as high as 98.12%, the acrolein selectivity is as high as 82.53%, and the total yield of acrolein and acrylic acid is 91.05%.

[0007] CN1210511A, CN1283604A, and CN1314331A achieve the purpose of controlling the reaction hot spots and prolonging the stability of the catalyst by configuring multiple catalyst layers with gradually increasing reaction activity along the axial direction of the reactor from the reaction gas inlet to the outlet. To control the reaction heat release, it is necessary to control the byproduct CO x The amount of production is due to the production of CO x The heat released by the production of acrolein and acrylic acid or other organic by-products is several times that of the production of x The higher it is, the greater the heat, the higher the hot spot temperature, and the worse the selectivity. Summary of the invention

[0008] The purpose of the present invention is to overcome the oxidation catalyst CO existing in the prior art x The present invention provides an oxidation catalyst and a preparation method and application thereof, and a method for propylene oxidation. The catalyst is used for olefin oxidation, such as propylene oxidation to prepare acrolein and acrylic acid, and has CO x The advantages of low yield and high product selectivity.

[0009] In order to achieve the above object, the present invention provides an oxidation catalyst in the first aspect, the composition formula of the catalyst is expressed as: MoBi a Fe b Co c X d Y e Z f O j , wherein 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, and the value of a is 0.1-0.5; b is the molar ratio of Fe to Mo, and the value of b is 0.1-0.5; c is the molar ratio of Co to Mo, and the value of c is 0.1-1.5; d is the molar ratio of X to Mo, and the value of d is 0.1-0.5; e is the molar ratio of Y to Mo, and the value of e is 0.1-0.5; f is the molar ratio of Z to Mo, and the value of f is 0.01-0.06; 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 the average pore diameter of the catalyst is greater than 70nm.

[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) dissolving a Mo compound and a Z compound in water to obtain a first solution; dissolving a Bi compound, a Fe compound, a Co compound, a Y compound and an X compound in water to obtain a second solution; mixing the first solution with the second solution, concentrating and drying to obtain a solid; pre-calcining the solid and grinding it into a fine powder with a particle size of less than 15 microns;

[0013] (2) Dispersing the fine powder in a solvent to obtain a slurry, spray drying the slurry and then calcining it to obtain a 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°C.

[0014] The third aspect of the present invention provides a use of the oxidation catalyst in the preparation of olefins and / or olefinic acids by oxidation of olefins.

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

[0016] The present invention adopts the method of drying and pre-burning first and then grinding, and then preparing fine powder into slurry, spray drying and molding at a relatively high spray drying hot air inlet temperature and appropriately reducing the solid content of the slurry to obtain a hollow thin-shell microsphere catalyst with a relatively large pore size.

[0017] The oxidation catalyst of the present invention has a hollow thin shell structure, and according to a preferred embodiment of the present invention, the catalyst has a relatively large pore size. The oxidation catalyst of the present invention is used for oxidizing olefins (such as propylene) to prepare olefin aldehydes and / or olefin acids (such as acrolein and / or acrylic acid), and has CO x The advantages of low yield and high product selectivity.

[0018] It is speculated that the catalyst has a hollow thin shell structure and a large pore size, which increases the diffusion rate of reactants and products, greatly shortens the path, and is very convenient for heat to be removed from the catalyst, which can effectively reduce the occurrence of deep oxidation reactions and reduce CO x The yield can be reduced, thereby reducing the generation of reaction heat, effectively controlling the reaction hot spot temperature, and improving the selectivity of the target product. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 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 DESCRIPTION

[0021] The endpoints and any values ​​of the ranges disclosed in this article 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0022] The first aspect of the present invention provides an oxidation catalyst, the composition of the catalyst is represented by the general formula: MoBi a Fe b Co c X d Y e Z f O j , wherein 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, and the value of a is 0.1-0.5; b is the molar ratio of Fe to Mo, and the value of b is 0.1-0.5; c is the molar ratio of Co to Mo, and the value of c is 0.1-1.5; d is the molar ratio of X to Mo, and the value of d is 0.1-0.5; e is the molar ratio of Y to Mo, and the value of e is 0.1-0.5; f is the molar ratio of Z to Mo, and the value of f is 0.01-0.06; 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 the average pore diameter of the catalyst is greater than 70nm.

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

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

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

[0027] In the present 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 Mg and Cu at the same time, the molar ratio of Mg to Cu is preferably 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) dissolving a Mo compound and a Z compound in water to obtain a first solution; dissolving a Bi compound, a Fe compound, a Co compound, a Y compound and an X compound in water to obtain a second solution; mixing the first solution with the second solution, concentrating and drying to obtain a solid; pre-calcining the solid and grinding it into a fine powder with a particle size of less than 15 microns;

[0039] (2) Dispersing the fine powder in a solvent to obtain a slurry, spray drying the slurry and then calcining it to obtain a 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°C. The present invention adopts the method of first drying and pre-calcining and then grinding, and then preparing the fine powder into a slurry, spray drying at a higher spray drying hot air inlet temperature, and appropriately reducing the solid content of the slurry, and spray drying to obtain a catalyst with a hollow thin shell structure with a larger pore size.

[0040] In the present invention, there is no limitation on the order of preparing 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: the hot air inlet temperature is 450-550°C.

[0043] In the present invention, in step (1), the conditions for concentrating and drying to obtain a solid can be selected in a wide range. According to a preferred embodiment of the present 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 the present invention, in step (1), the range of optional pre-firing conditions is relatively wide. According to a preferred embodiment of the present invention, the pre-firing conditions include: a temperature of 180-250°C; the pre-firing time can be reasonably adjusted according to actual needs, preferably, the pre-firing time is 1-3h.

[0045] In the present invention, in step (2), the present invention has no particular limitation on the solvent, which can be a conventional solvent in the art, such as water; the method of dispersing the fine powder in the solvent to obtain a slurry is not particularly limited, for example, a suitable amount of water can be added to the fine powder, and the slurry can be obtained by high-speed shear mixing.

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

[0047] According to some embodiments of the preparation method of the present invention, the calcination conditions include: a temperature of 400-650° C., such as 400° C., 450° C., 500° C., 550° C., 600° C., 650° C., and any value therebetween.

[0048] According to some embodiments of the preparation method of the present invention, the calcination conditions include: a time of 1 to 12 hours, such as 1 hour, 3 hours, 5 hours, 7 hours, 9 hours, 10 hours, 12 hours, and any value therebetween.

[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 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 selection range, with the purpose of being able to fully dissolve the compound.

[0052] According to a preferred embodiment of the present invention, the Mo compound, the Y compound, the Bi compound, the Fe compound, the Co compound, the X compound and the Z compound can 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 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 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 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 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 can be selected from but 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 can be selected from but 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 can be selected from but 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] The third aspect of the present invention provides an application of the oxidation catalyst in the oxidation of olefins to prepare olefin aldehydes and / or olefin acids. The oxidation catalyst of the present invention is used for the oxidation of olefins (such as propylene) to prepare olefin aldehydes and / or olefin acids (such as acrolein and / or acrylic acid), and has CO x The advantages of low yield and high product selectivity.

[0061] The fourth aspect of the present invention provides a method for preparing acrolein, the method comprising: contacting a raw material gas containing propylene, an oxidizing gas containing oxygen and a catalyst to prepare acrolein and / or acrylic acid; the catalyst is the oxidation catalyst of the present invention. The oxidation catalyst of the present invention is used for oxidizing olefins (such as propylene) to prepare olefinic aldehydes and / or olefinic acids (such as acrolein and / or acrylic acid), and has CO x 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 a gauge pressure.

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

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

[0066] According to a preferred embodiment of the present invention, in order to make the reaction more stable and controllable, the raw gas further contains a diluent gas phase material; in terms of volume ratio, propylene: diluent gas phase material = 1: (0.5-5).

[0067] According to a preferred embodiment of the present invention, the diluent gas phase material is water vapor.

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

[0069] In order to make the present invention more easily understood, the present invention will be described in detail below in conjunction with embodiments. These embodiments are only for illustration and are not intended to limit the application scope 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 g

[0073] Reaction temperature: 380℃

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

[0075] Propylene: air (raw material molar ratio) = 1: 7.1

[0076] Propylene: water vapor = 1: 1.9

[0077] Raw gas volume mass space velocity: 1000mL / g·h

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

[0079] Propylene conversion, product yield and selectivity are defined as:

[0080]

[0081]

[0082]

[0083] Example 1

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

[0085] (2) Add 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 a slurry. Adjust the hot air inlet temperature of the sprayer to 450°C, spray dry. Then calcine in air at 550°C 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] The SEM images of the catalyst are shown in Figure 1 As shown, the catalyst has a hollow thin shell structure, the average particle size of the catalyst is 72 μm, the average shell thickness is 5.3 μm; the average pore size of the catalyst is 106 nm.

[0088] Example 2

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

[0090] (2) Add 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 a slurry. Adjust the hot air inlet temperature of the sprayer to 450°C, spray dry. Then calcine in air at 550°C 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, the average particle size of the catalyst is 74 μm, the average shell thickness is 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 ammonium molybdate equivalent to 1 mol of Mo and 0.01 mol of cesium hydroxide equivalent to Cs and dissolve them in 200 g of water to obtain a first solution. Weigh bismuth nitrate equivalent to 0.5 mol of Bi, ferric nitrate equivalent to 0.1 mol of Fe, calcium nitrate equivalent to 0.1 mol of Ca, copper nitrate equivalent to 0.4 mol of Cu, cobalt nitrate equivalent to 0.1 mol of Co, cerium nitrate equivalent to 0.4 mol of Ce and samarium nitrate equivalent to 0.1 mol of Sm and dissolve them in 200 g of water to obtain a second solution. Mix the first solution and the second solution, evaporate and concentrate at 70°C, pre-calculate at 200°C for 2 hours, grind and sieve through 1000 mesh to obtain fine powder.

[0095] (2) Add 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 a slurry. Adjust the hot air inlet temperature of the sprayer to 450°C, spray dry. Then calcine in air at 550°C 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, the average particle size of the catalyst is 75 μm, the average shell thickness is 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 ammonium molybdate equivalent to 1 mol of Mo and potassium hydroxide equivalent to 0.02 mol of K and dissolve them in 200 g of water to obtain a first solution. Weigh bismuth nitrate equivalent to 0.3 mol of Bi, ferric nitrate equivalent to 0.4 mol of Fe, magnesium nitrate equivalent to 0.2 mol of Mg, copper nitrate equivalent to 0.2 mol of Cu, cobalt nitrate equivalent to 0.3 mol of Co, and lanthanum nitrate equivalent to 0.4 mol of La and dissolve them in 200 g of water to obtain a second solution. Mix the first solution and the second solution, evaporate and concentrate at 70°C, pre-calculate at 200°C for 2 hours, grind and sieve through 1000 mesh to obtain a fine powder.

[0100] (2) Add 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 a slurry. Adjust the hot air inlet temperature of the sprayer to 450°C, spray dry. Then calcine in air at 550°C 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, it indicates that the catalyst has a hollow thin shell structure, the average particle size of the catalyst is 70 μm, the average shell thickness is 5.5 μm; the average pore size of the catalyst is 98 nm.

[0103] Example 5

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

[0105] (2) Add 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 a slurry. Adjust the hot air inlet temperature of the sprayer to 450°C, spray dry. Then calcine in air at 550°C 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, it indicates that the catalyst has a hollow thin shell structure, the diameter of the catalyst is 77 μm, the shell thickness is 5.4 μm; the average pore size of the catalyst is 102 nm.

[0108] Example 6

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

[0110] (2) Add 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 a slurry. Adjust the hot air inlet temperature of the sprayer to 450°C, spray dry. Then calcine in air at 550°C 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, it indicates that the catalyst has a hollow thin shell structure, the average particle size of the catalyst is 71 μm, the average shell thickness is 5.2 μm; the average pore size of the catalyst is 105 nm.

[0113] Comparative Example 1

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

[0115] (2) Add 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 a slurry. Adjust the hot air inlet temperature of the sprayer to 450°C, spray dry. Then calcine in air at 550°C 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] The SEM images of the catalyst are shown in Figure 2 As shown, it indicates that the catalyst has a solid structure and the average diameter of the catalyst microspheres is 74 μm.

[0118] Comparative Example 2

[0119] Weigh ammonium molybdate equivalent to 1 mol of Mo and potassium hydroxide equivalent to 0.02 mol of K and dissolve them in 200 grams of water to obtain a first solution. Weigh bismuth nitrate equivalent to 0.3 mol of Bi, 0.4 mol of iron nitrate of Fe, 0.4 mol of magnesium nitrate of Mg, 0.3 mol of cobalt nitrate of Co, and 0.4 mol of lanthanum nitrate of La and dissolve them in 200 grams of water to obtain a second solution. Mix the first solution and the second solution, add an appropriate amount of water to adjust the solid content of the slurry to 25%, and shear disperse for 30 minutes to obtain a slurry. Adjust the hot air inlet temperature of the sprayer to 450°C and spray dry. Then roast in an air atmosphere 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, it indicates that the catalyst has a hollow thin shell structure, the catalyst diameter is 73μm, the shell thickness is 4.8μm; the average pore diameter is 32nm.

[0122] Comparative Example 3

[0123] Weigh ammonium molybdate equivalent to 1 mol of Mo and potassium hydroxide equivalent to 0.02 mol of K and dissolve them in 200 g of water to obtain a first solution. Weigh bismuth nitrate equivalent to 0.3 mol of Bi, ferric nitrate equivalent to 0.4 mol of Fe, magnesium nitrate equivalent to 0.4 mol of Mg, cobalt nitrate equivalent to 0.3 mol of Co, and lanthanum nitrate equivalent to 0.4 mol of La and dissolve them in 200 g of water to obtain a second solution. Mix the first solution and the second solution, shear and disperse for 30 minutes to obtain a slurry. After concentrating at 80°C, bake at 120 for 8 hours. Then roast in an air atmosphere at 550°C 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 , crush and screen the 5-150 micron part, and the average diameter of the catalyst is 75μm.

[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 are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. An oxidation catalyst, characterized in that The general formula of the catalyst components is: MoBi a Fe b Co c X d Y e Z f O j , wherein 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, and the value of a is 0.1-0.5; b is the molar ratio of Fe to Mo, and the value of b is 0.1-0.5; c is the molar ratio of Co to Mo, and the value of c is 0.1-1.5; d is the molar ratio of X to Mo, and the value of d is 0.1-0.5; e is the molar ratio of Y to Mo, and the value of e is 0.1-0.5; f is the molar ratio of Z to Mo, and the value of f is 0.01-0.06; 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 the average pore diameter of the catalyst is greater than 70nm.

2. The oxidation catalyst according to claim 1, wherein The catalyst has a diameter of 5-150 microns and a shell thickness of 0.5-15 microns; and / or The average pore size of the oxidation catalyst is 85-200 nm; and / or X is selected from at least two of Mg, Ca, Cu and Zn; and / or Y is La and Ce.

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

04.

4. A method for preparing an oxidation catalyst according to any one of claims 1 to 3, characterized in that: The method includes: (1) dissolving a Mo compound and a Z compound in water to obtain a first solution; dissolving a Bi compound, a Fe compound, a Co compound, a Y compound and an X compound in water to obtain a second solution; mixing the first solution with the second solution, concentrating and drying to obtain a solid; pre-calcining the solid and grinding it into a fine powder with a particle size of less than 15 microns; (2) Dispersing the fine powder in a solvent to obtain a slurry, spray drying the slurry and then calcining it to obtain a 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°C.

5. The preparation method according to claim 4, wherein: In step (2), the solid content of the slurry is 20-30 wt %; and / or The hot air inlet temperature is 450-550℃.

6. The preparation method according to claim 4 or 5, wherein: In step (1), the concentration conditions include: a temperature of 60-80°C; and / or Drying conditions include: temperature of 100-150°C; and / or The pre-firing conditions include: a temperature of 180-250°C; and / or a pre-firing time of 1-3 hours; and / or In step (2), the calcination conditions include: a temperature of 400 to 650° C.; and / or a time of 1 to 12 hours.

7. Use of the oxidation catalyst according to any one of claims 1 to 3 in the preparation of olefins and / or olefinic acids by oxidation of olefins.

8. A method for propylene oxidation, characterized in that: The method comprises: contacting a raw material gas containing propylene, an oxidizing gas containing oxygen and a catalyst to prepare acrolein and / or acrylic acid; the catalyst comprises the oxidation catalyst described in any one of claims 1-3.

9. The method according to claim 8, wherein: Contact conditions include: The temperature is 100-500°C, preferably 350-420°C; The pressure is 0.01-0.05MPa, and the pressure is gauge pressure; The raw gas volume mass space velocity is 800-1200mL / g·h; and / or In terms of volume ratio, propylene: oxygen-containing oxidizing gas = 1: (6-8).

10. The method according to claim 8 or 9, wherein: The raw gas also contains diluent gas phase material; in terms of volume ratio, propylene: diluent gas phase material = 1: (0.5-5); Preferably, the diluent gaseous material is water vapor; and / or The oxygen-containing oxidizing gas is one or more of oxygen and air, more preferably air.

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