Oxidation catalysts, their preparation methods and applications, and selective oxidation methods for propylene

Abstract

This invention relates to the field of catalyst technology, specifically to an oxidation catalyst, its preparation method and application, and a method for selective oxidation of propylene. The catalyst has the general formula: Bi. a / (MoFe b X c Y d Z e )O j In this catalyst, X is selected from at least one of Mg, Co, Ni, Ca, Cu, Zn, and Mn; Y is selected from at least one of La and Ce; and Z is selected from at least one of K, Rb, Na, and Cs. The surface dispersion of Bi element is 1-3. This catalyst is used in oxidation reactions, such as the selective oxidation of propylene to acrolein and / or acrylic acid, and has the advantages of high total yield of acrolein and acrylic acid, as well as good catalyst structural stability.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to an oxidation catalyst, its preparation method and application, and a method for selective oxidation of propylene. 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 onto the catalyst surface, and an α-H atom is removed by a metal oxide, forming a free radical intermediate. This intermediate then generates the product through oxygen-nitrogen intercalation. During this process, the catalyst undergoes a redox cycle, losing the oxygen atom involved in the intercalation reaction, becoming reduced, and then re-oxidized by oxygen in the reaction gas. The active oxygen site is replenished through oxygen migration. Therefore, the catalyst must possess 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 commonly 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] CN1564709 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. However, the structural stability of these catalysts needs further improvement. Summary of the Invention

[0008] The purpose of this invention is to overcome the problems of low structural stability of existing oxidation catalysts and low yield of target products in oxidation catalysis. This invention provides an oxidation catalyst, its preparation method and application, and a method for selective oxidation of propylene. When this catalyst is used in oxidation reactions, such as the selective oxidation of propylene to prepare acrolein and / or acrylic acid, it has the advantages of high total yield of acrolein and acrylic acid, and good structural stability.

[0009] To achieve the above objectives, the present invention provides an oxidation catalyst, wherein the catalyst has the general formula: Bi a / (MoFe b X c Y d Z e )O j Where X is selected from at least one of Mg, Co, Ni, Ca, Cu, Zn, and Mn; Y is selected from at least one of La and Ce; Z is selected from at least one of K, Rb, Na, and Cs; a is the molar ratio of Bi to Mo, with a value of 0.1 to 0.3; b is the molar ratio of Fe to Mo, with a value of 0.1 to 0.5; c is the molar ratio of X to Mo, with a value of 0.5 to 1.5; d is the molar ratio of Y to Mo, with a value of 0.1 to 0.5; e is the molar ratio of Z to Mo, with a value of 0.01 to 0.06; j is the total number of oxygen atoms required to satisfy the valence of other elements; in the catalyst,

[0010] The surface dispersion of Bi element is 1-3.

[0011]

[0012] A second aspect of the present invention provides a method for preparing an oxidation catalyst, the method comprising:

[0013] (1) Dissolve the Mo compound and Z compound in water to form a first solution; dissolve the Fe compound, X compound and Y compound in water to obtain a second solution; mix the first solution and the second solution to obtain a slurry, concentrate, dry and calcine to obtain a solid precursor;

[0014] (2) The solid precursor is crushed, molded with binder and water, dried and calcined to obtain the molded precursor;

[0015] (3) Dissolve the Bi compound in an acidic solution to obtain a third solution, impregnate the third solution onto the molding precursor, and dry and calcine to obtain the catalyst.

[0016] A third aspect of the present invention provides an oxidation catalyst prepared by the preparation method described herein.

[0017] The fourth aspect of the present invention provides the application of the oxidation catalyst described in the present invention or the oxidation catalyst prepared by the preparation method described therein in the oxidation of olefins to prepare enaldehydes and / or olefinic acids.

[0018] The fifth aspect of the present invention provides a method for selective oxidation of propylene, 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 comprises the oxidation catalyst described in the present invention or an oxidation catalyst prepared by the preparation method described in the present invention.

[0019] Through the above technical solution, in the oxidation catalyst of the present invention, the active component Bi is distributed in the catalyst, and Bi has good dispersion on the catalyst surface, which can form abundant surface active sites, thereby improving the oxidation activity of the catalyst and the product yield.

[0020] Mo-Bi composite oxide systems are important catalytic systems for the selective oxidation of olefins or ammonia oxidation, and Bi is considered a key active site for the first step of dehydrogenation. The catalyst described in this invention can better disperse the Bi component and expose it to the surface accessible to the reactant gases, providing more Bi-O active sites. Therefore, it can significantly improve the catalytic performance of the catalyst, especially under high loading conditions.

[0021] The catalyst described in this invention is used for the oxidation of olefins (e.g., propylene) to prepare enaldehydes (e.g., acrolein) and olefinic acids (e.g., acrylic acid), and has the advantage of high total yield of enaldehydes and olefinic acids, especially under high loading conditions.

[0022] The method for preparing the oxidation catalyst described in this invention involves first molding and then loading Bi in an acidic solution. This avoids Bi precipitation being covered by other components and also prevents the Bi component from being masked during the secondary molding process. It can better disperse and expose the Bi component on the surface accessible to the reaction gas, providing more Bi-O active sites. Detailed Implementation

[0023] 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.

[0024] In this invention, the high-load condition in the reaction of olefin (e.g., propylene) oxidation to prepare aldehyde (e.g., acrolein) and olefinic acid (e.g., acrylic acid) refers to a feed gas volume hourly space velocity of 1500–3000 mL / g·h.

[0025] This invention provides an oxidation catalyst, the catalyst having the general formula: Bi a / (MoFe b X c Y d Z e )O j Where X is selected from at least one of Mg, Co, Ni, Ca, Cu, Zn, and Mn; Y is selected from at least one of La and Ce; Z is selected from at least one of K, Rb, Na, and Cs; a is the molar ratio of Bi to Mo, with a value of 0.1 to 0.3; b is the molar ratio of Fe to Mo, with a value of 0.1 to 0.5; c is the molar ratio of X to Mo, with a value of 0.5 to 1.5; d is the molar ratio of Y to Mo, with a value of 0.1 to 0.5; e is the molar ratio of Z to Mo, with a value of 0.01 to 0.06; j is the total number of oxygen atoms required to satisfy the valence of other elements; in the catalyst,

[0026]

[0027] The surface dispersion of Bi element is 1-3.

[0028] In the oxidation catalyst described in this invention, by changing the distribution of the key active component Bi in the catalyst, Bi has good dispersion on the catalyst surface, which can form abundant surface active sites, thereby improving the oxidation activity of the catalyst and the product yield.

[0029] In this invention, the Bi content and the total metal content on the catalyst surface were obtained by XPS measurement. The Bi content and the total metal content in the catalyst were obtained by ICP testing.

[0030] According to a preferred embodiment of the present invention, the surface dispersion of Bi element is 1.2-2.8.

[0031] According to a preferred embodiment of the present invention, the value of 'a' is 0.15-0.2. This is beneficial for improving the oxidation activity of the catalyst and the product yield.

[0032] According to a preferred embodiment of the present invention, the value of b is 0.15 to 0.3. This is beneficial for improving the oxidation activity of the catalyst and the product yield.

[0033] According to a preferred embodiment of the present invention, the value of c is 0.7-1.2. This is beneficial for improving the oxidation activity of the catalyst and the product yield.

[0034] According to a preferred embodiment of the present invention, the value of d is 0.15 to 0.3. This is beneficial for improving the oxidation activity of the catalyst and the product yield.

[0035] According to a preferred embodiment of the present invention, the value of e is 0.02 to 0.05. This is beneficial for improving the oxidation activity of the catalyst and the product yield.

[0036] According to a preferred embodiment of the present invention, X is selected from Co and Ni, preferably, the molar ratio of Co and Ni is 0.5-2; the oxidation catalyst of the present invention contains both Co and Ni, which have a synergistic effect and can improve the oxidation activity of the catalyst and the product yield.

[0037] According to a preferred embodiment of the present invention, Y is selected from La and Ce, and preferably, the molar ratio of La to Ce is 0.5-2; the oxidation catalyst of the present invention contains both La and Ce, which have a synergistic effect and can improve the oxidation activity of the catalyst and the product yield.

[0038] A second aspect of the present invention provides a method for preparing an oxidation catalyst, the method comprising:

[0039] (1) Dissolve the Mo compound and Z compound in water to form a first solution; dissolve the Fe compound, X compound and Y compound in water to obtain a second solution; mix the first solution and the second solution to obtain a slurry, concentrate, dry and calcine to obtain a solid precursor;

[0040] (2) The solid precursor is crushed, molded with binder and water, dried and calcined to obtain the molded precursor;

[0041] (3) The Bi compound is dissolved in an acidic solution to obtain a third solution. The third solution is then impregnated onto the molding precursor, dried, and calcined to obtain the catalyst. By first molding and then loading Bi in the acidic solution, Bi precipitation can be avoided from being covered by other components. It can also avoid the Bi component being masked during the secondary molding process, and can better disperse and expose the Bi component on the surface accessible to the reactant gas, providing more Bi-O active sites.

[0042] In this invention, the amount of each substance fed satisfies the general formula of the catalyst to be prepared: Bi a / (MoFe b X c Y d Z e )O j Wherein, X is selected from at least one of Mg, Co, Ni, Ca, Cu, Zn, and Mn; Y is selected from at least one of La and Ce; Z is selected from at least one of K, Rb, Na, and Cs; a is the molar ratio of Bi to Mo, with a value of 0.1 to 0.3; b is the molar ratio of Fe to Mo, with a value of 0.1 to 0.5; c is the molar ratio of X to Mo, with a value of 0.5 to 1.5; d is the molar ratio of Y to Mo, with a value of 0.1 to 0.5; e is the molar ratio of Z to Mo, with a value of 0.01 to 0.06; and j is the total number of oxygen atoms required to satisfy the valence of other elements.

[0043] According to a preferred embodiment of the present invention, the Mo compound, Y compound, Bi compound, Fe compound, X compound and Z compound may be selected from nitrates, ammonium salts, sulfates, oxides, hydroxides, chlorides, acetates and the like.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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 the following: cobalt nitrate, cobalt sulfate, cobalt chloride, magnesium nitrate, magnesium sulfate, magnesium chloride, magnesium oxide, magnesium acetate, nickel nitrate, nickel sulfate, nickel chloride, calcium nitrate, calcium acetate, calcium chloride, copper nitrate, zinc nitrate, and manganese nitrate.

[0048] 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, and cerium acetate.

[0049] 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, and cesium nitrate.

[0050] According to a preferred embodiment of the present invention, the amount of water in the first and second solutions and the amount of nitric acid solution in the third solution have a wide range of selection, with the aim of fully dissolving the compound.

[0051] According to a preferred embodiment of the present invention, in step (2), the solid precursor is broken into particles smaller than 100 micrometers.

[0052] In this invention, the range of drying conditions that can be selected in step (2) is relatively wide. According to a preferred embodiment of this invention, the drying conditions include: a temperature of 100-150℃; and the drying time can be reasonably determined according to actual needs. Preferably, the time is 1-4 hours.

[0053] 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 350-450℃; and the roasting time can be reasonably determined according to actual needs. Preferably, the time is 1-3h.

[0054] In this invention, the range of types of adhesives that can be selected in step (2) is relatively wide, as long as they can bond the wet material into shape. According to a preferred embodiment of this invention, the adhesive is selected from at least one of methylcellulose, hydroxypropyl methylcellulose and carboxymethylcellulose.

[0055] In this invention, in step (2), there is no particular limitation on the shape of the molding precursor, as long as it is suitable for filling the reactor. For example, the molding precursor can be prepared into Raschig rings, spheres, gears, and honeycomb shapes.

[0056] According to a preferred embodiment of the present invention, in step (3), the mass concentration of the acid in the acid-containing solution is 3wt-20wt%; preferably, the acid is selected from nitric acid.

[0057] According to a preferred embodiment of the present invention, in step (3), the impregnation method is equal volume impregnation.

[0058] In this invention, the range of drying conditions that can be selected in step (3) is relatively wide. According to a preferred embodiment of this invention, the drying conditions include: a temperature of 80-100℃; and the drying time can be reasonably determined according to actual needs. Preferably, the time is 2-10h.

[0059] In this invention, the range of roasting conditions that can be selected in step (3) is relatively wide. According to a preferred embodiment of this invention, the roasting conditions include: a temperature of 500-600℃; and the roasting time can be reasonably determined according to actual needs. Preferably, the time is 1-6h.

[0060] According to a preferred embodiment of the present invention, in steps (2) and (3), the roasting atmosphere is an atmosphere containing O2. However, from an economic point of view, the roasting atmosphere is preferably air. Unless otherwise specified, the roasting atmosphere in the present invention is always air.

[0061] According to a preferred embodiment of the present invention, the solution after mixing of each process is a homogeneous solution, a suspension, or a mixture of solution and suspension.

[0062] In this invention, a solid can be obtained through steps such as concentration. For this invention, it is preferred to obtain the solid by evaporation and concentration at 60-80°C.

[0063] A third aspect of this invention provides the application of the oxidation catalyst described herein or the oxidation catalyst prepared by the method described herein in the oxidation of olefins to prepare enaldehydes and / or olefinic acids. The catalyst described herein, used in the oxidation of olefins (e.g., propylene) to prepare enaldehydes (e.g., acrolein) and olefinic acids (e.g., acrylic acid), has the advantage of high total yield of enaldehydes and olefinic acids, especially under high loading conditions.

[0064] A fourth aspect of the present invention provides a method for selective oxidation of propylene, 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 comprises the oxidation catalyst described in the present invention or an oxidation catalyst prepared by the preparation method described in the present invention.

[0065] According to a preferred embodiment of the present invention, the contact conditions include a temperature of 300-550°C, preferably 330-380°C.

[0066] According to a preferred embodiment of the present invention, the contact conditions include a pressure of 0.01 to 0.08 MPa, wherein the pressure is gauge pressure.

[0067] According to a preferred embodiment of the present invention, the contact conditions include: the volumetric hourly space velocity of the feed gas is 1500-3000 mL / g·h.

[0068] According to a preferred embodiment of the present invention, the contact conditions include: propylene: oxygen-containing oxidizing gas = 1:(6-8) by volume.

[0069] 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 diluent gaseous material; by volume ratio, propylene: diluent gaseous material = 1:(0.5~5).

[0070] According to a preferred embodiment of the present invention, the dilutive gaseous material is water vapor.

[0071] 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.

[0072] In the following examples and comparative examples, the catalyst evaluation conditions are as follows:

[0073] Reactor: Fixed-bed single-tube reactor, inner diameter 26.0 mm, reactor length 800 mm

[0074] Catalyst: 200 grams

[0075] Reaction temperature: 360℃

[0076] Reaction pressure: 0.05 MPa (gauge pressure)

[0077] Propylene:Air (feedstock molar ratio) = 1:7.2

[0078] Propylene:water vapor = 1:1.8

[0079] Feed gas volumetric hourly space velocity: 2000 mL / g·h

[0080] 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%).

[0081] The definitions of propylene conversion, product yield, and selectivity are as follows:

[0082]

[0083]

[0084]

[0085] Example 1

[0086] (1) Weigh out 1 mole of molybdate and 0.04 mole of potassium hydroxide and dissolve them in 200 mL of water to form a first solution; weigh out 0.2 mole of ferric nitrate, 0.7 mole of cobalt nitrate, 0.2 mole of nickel nitrate and 0.2 mole of cerium nitrate and dissolve them in 200 mL of water to form a second solution. Mix the first solution and the second solution to obtain a slurry, concentrate it at 70 °C, dry it at 100 °C for 12 h, and then calcine it at 300 °C for 2 h to obtain a solid precursor.

[0087] (2) Crush the solid precursor, sieve it through a 200-mesh screen, add water and methylcellulose, extrude and cut it into Raschig rings with an outer diameter of 5 mm, an inner diameter of 3.5 mm and a length of 4.5 mm, dry it at 120℃ for 3 h, and calcine it at 400℃ for 2 h to obtain the shaped precursor.

[0088] (3) Weigh out 0.2 mol of bismuth nitrate and dissolve it in 50 g of 10 wt% nitric acid solution to obtain a third solution. Impregnate the molding precursor with an equal volume of the third solution, bake at 90 °C for 6 h, and calcine at 550 °C for 4 h to obtain catalyst Bi. 0.2 / (MoFe 0.2 Co 0.7 Ni 0.2 Ce 0.2 K 0.04 )O j .

[0089] Example 2

[0090] (1) Weigh out 1 mole of molybdate and 0.01 mole of cesium hydroxide and dissolve them in 200 mL of water to form a first solution; weigh out 0.1 mole of ferric nitrate, 1.5 mole of cobalt nitrate, 0.2 mole of cerium nitrate, and 0.3 mole of lanthanum nitrate and dissolve them in 200 mL of water to form a second solution. Mix the first solution and the second solution to obtain a slurry, concentrate it at 70 °C, dry it at 100 °C for 12 h, and then calcine it at 300 °C for 2 h to obtain a solid precursor.

[0091] (2) The solid precursor was crushed, sieved through a 200-mesh sieve, and water and methylcellulose were added. The extruded strips were cut into Raschig rings with an outer diameter of 5 mm, an inner diameter of 3.5 mm, and a length of 4.5 mm. The strips were dried at 120°C for 3 h and calcined at 400°C for 2 h to obtain the shaped precursor.

[0092] (3) Weigh out 0.1 mol of bismuth nitrate and dissolve it in 50 g of a 10% nitric acid solution to obtain a third solution. Impregnate the molding precursor with the third solution, bake at 90°C for 6 h, and calcine at 550°C for 4 h to obtain catalyst Bi. 0.1 / (MoFe 0.1 Co 1.5 Ce0.2 La 0.3 Cs 0.01 )O j .

[0093] Example 3

[0094] (1) Weigh out 1 mole of molybdate, 0.04 mole of potassium hydroxide and 0.01 mole of sodium hydroxide and dissolve them in 200 mL of water to form a first solution; weigh out 0.5 mole of ferric nitrate, 0.5 mole of copper nitrate and 0.1 mole of cerium nitrate and dissolve them in 200 mL of water to form a second solution. Mix the first solution and the second solution to obtain a slurry, concentrate it at 70 °C, dry it at 100 °C for 12 h, and then calcine it at 300 °C for 2 h to obtain a solid precursor.

[0095] (2) The solid precursor was crushed and sieved through a 200-mesh sieve. A suitable amount of water and methylcellulose were added and extruded into Raschig rings with an outer diameter of 5 mm, an inner diameter of 3.5 mm, and a length of 4.5 mm. The rings were dried at 120°C for 3 h and calcined at 400°C for 2 h to obtain the shaped precursor.

[0096] (3) Weigh out 0.3 moles of bismuth nitrate and dissolve it in 50 g of a 10% nitric acid solution to obtain a third solution. Impregnate the molding precursor with the third solution, bake at 90°C for 6 h, and calcine at 550°C for 4 h to obtain catalyst Bi. 0.3 / (MoFe 0.5 Cu 0.5 Ce 0.1 K 0.04 Na 0.01 )O j .

[0097] Example 4

[0098] (1) Weigh out 1 mole of molybdate and 0.04 mole of potassium hydroxide and dissolve them in 200 mL of water to form a first solution; weigh out 0.2 mole of ferric nitrate, 0.9 mole of cobalt nitrate and 0.2 mole of cerium nitrate and dissolve them in 200 mL of water to form a second solution. Mix the first solution and the second solution to obtain a slurry, concentrate it at 70 °C, dry it at 100 °C for 12 h, and then calcine it at 300 °C for 2 h to obtain a solid precursor.

[0099] (2) Crush the solid precursor, sieve it through a 200-mesh screen, add water and methylcellulose, extrude and cut it into Raschig rings with an outer diameter of 5 mm, an inner diameter of 3.5 mm and a length of 4.5 mm, dry it at 120℃ for 3 h, and calcine it at 400℃ for 2 h to obtain the shaped precursor.

[0100] (3) Weigh out 0.2 mol of bismuth nitrate and dissolve it in 50 g of 10 wt% nitric acid solution to obtain a third solution. Impregnate the molding precursor with an equal volume of the third solution, bake at 90 °C for 6 h, and calcine at 550 °C for 4 h to obtain catalyst Bi. 0.2 / (MoFe 0.2 Co 0.9 Ce 0.2 K 0.04 )O j .

[0101] The method of Example 1 is the same as that of Example 1, except that in step (1), cobalt nitrate equivalent to 0.2 moles of Co is used instead of nickel nitrate equivalent to 0.2 moles of Ni, and the other conditions are the same as those of Example 1.

[0102] Example 5

[0103] (1) Weigh out 1 mole of molybdate and 0.04 mole of potassium hydroxide and dissolve them in 200 mL of water to form a first solution; weigh out 0.2 mole of ferric nitrate, 0.7 mole of cobalt nitrate, 0.2 mole of nickel nitrate, 0.1 mole of lanthanum nitrate and 0.1 mole of cerium nitrate and dissolve them in 200 mL of water to form a second solution. Mix the first solution and the second solution to obtain a slurry, concentrate it at 70 °C, dry it at 100 °C for 12 h, and then calcine it at 300 °C for 2 h to obtain a solid precursor.

[0104] (2) Crush the solid precursor, sieve it through a 200-mesh screen, add water and methylcellulose, extrude and cut it into Raschig rings with an outer diameter of 5 mm, an inner diameter of 3.5 mm and a length of 4.5 mm, dry it at 120℃ for 3 h, and calcine it at 400℃ for 2 h to obtain the shaped precursor.

[0105] (3) Weigh out 0.2 mol of bismuth nitrate and dissolve it in 50 g of 10 wt% nitric acid solution to obtain a third solution. Impregnate the molding precursor with an equal volume of the third solution, bake at 90 °C for 6 h, and calcine at 550 °C for 4 h to obtain catalyst Bi. 0.2 / (MoFe 0.2 Co 0.7 Ni 0.2 La 0.1 Ce 0.1 K 0.04 )O j .

[0106] The method of Example 1 is the same as in Example 1, except that in step (1), lanthanum nitrate equivalent to 0.1 moles of La is used instead of cerium nitrate equivalent to 0.1 moles of Ce, and the other conditions are the same as in Example 1.

[0107] Example 6

[0108] (1) Weigh out 1 mole of molybdate and 0.04 mole of potassium hydroxide and dissolve them in 200 mL of water to form a first solution; weigh out 0.2 mole of ferric nitrate, 0.7 mole of cobalt nitrate, 0.2 mole of nickel nitrate and 0.2 mole of lanthanum nitrate and dissolve them in 200 mL of water to form a second solution. Mix the first solution and the second solution to obtain a slurry, concentrate it at 70 °C, dry it at 100 °C for 12 h, and then calcine it at 300 °C for 2 h to obtain a solid precursor.

[0109] (2) Crush the solid precursor, sieve it through a 200-mesh screen, add water and methylcellulose, extrude and cut it into Raschig rings with an outer diameter of 5 mm, an inner diameter of 3.5 mm and a length of 4.5 mm, dry it at 120℃ for 3 h, and calcine it at 400℃ for 2 h to obtain the shaped precursor.

[0110] (3) Weigh out 0.2 mol of bismuth nitrate and dissolve it in 50 g of 10 wt% nitric acid solution to obtain a third solution. Impregnate the molding precursor with an equal volume of the third solution, bake at 90 °C for 6 h, and calcine at 550 °C for 4 h to obtain catalyst Bi. 0.2 / (MoFe 0.2 Co 0.7 Ni 0.2 La 0.2 K 0.04 )O j .

[0111] The method of Example 1 is the same as in Example 1, except that in step (1), lanthanum nitrate equivalent to 0.2 moles of La is used instead of cerium nitrate equivalent to 0.2 moles of Ce, and the other conditions are the same as in Example 1.

[0112] Comparative Example 1

[0113] (1) Weigh out 1 mole of molybdate and 0.04 mole of potassium hydroxide and dissolve them in 200 mL of water to form a first solution; weigh out 0.2 mole of ferric nitrate, 0.2 mole of bismuth nitrate, 0.7 mole of cobalt nitrate, 0.2 mole of nickel nitrate and 0.2 mole of cerium nitrate and dissolve them in 200 mL of water to form a second solution; mix the first solution and the second solution to obtain a slurry; concentrate at 70 °C; dry at 100 °C for 12 h; and calcine at 300 °C for 2 h to obtain a solid precursor.

[0114] (2) The solid precursor was crushed, sieved through a 200-mesh sieve, and then mixed with an appropriate amount of water and methylcellulose. The mixture was extruded and cut into Raschig rings with an outer diameter of 5 mm, an inner diameter of 3.5 mm, and a length of 4.5 mm. The rings were dried at 120℃ for 3 h and calcined at 400℃ for 2 h to obtain the shaped precursor. The precursor was then dried at 90℃ for 6 h and calcined at 550℃ for 4 h to obtain the catalyst Bi. 0.2 MoFe0.2 Co 0.7 Ni 0.2 Ce 0.2 K 0.04 O j .

[0115] Comparative Example 2

[0116] (1) Weigh out 1 mole of molybdate and 0.04 mole of potassium hydroxide and dissolve them in 200 mL of water to form a first solution; weigh out 0.2 mole of ferric nitrate, 0.7 mole of cobalt nitrate, 0.2 mole of nickel nitrate and 0.2 mole of cerium nitrate and dissolve them in 200 mL of water to form a second solution. Mix the first solution and the second solution to obtain a slurry, concentrate it at 70 °C, dry it at 100 °C for 12 h, and then calcine it at 300 °C for 2 h to obtain a solid precursor.

[0117] (2) The solid precursor was crushed and sieved through a 200-mesh sieve. Bismuth nitrate equivalent to 0.2 mol Bi was dissolved in a suitable amount of 10% nitric acid solution to obtain a third solution. This third solution was loaded onto the crushed solid precursor, and a suitable amount of water and methylcellulose were added. The extruded strips were cut into Raschig rings with an outer diameter of 5 mm, an inner diameter of 3.5 mm, and a length of 4.5 mm. The rings were dried at 120℃ for 3 h and calcined at 400℃ for 2 h to obtain the shaped precursor. The precursor was then dried at 90℃ for 6 h and calcined at 550℃ for 4 h to obtain the catalyst Bi. 0.2 MoFe 0.2 Co 0.7 Ni 0.2 Ce 0.2 K 0.04 O j .

[0118] Comparative Example 3

[0119] The method of Example 1 is followed, except that an equal mass of water is used instead of nitric acid solution, while the other conditions are the same as in Example 1; specifically as follows:

[0120] (1) Weigh out 1 mole of molybdate and 0.04 mole of potassium hydroxide and dissolve them in 200 mL of water to form a first solution; weigh out 0.2 mole of ferric nitrate, 0.7 mole of cobalt nitrate, 0.2 mole of nickel nitrate and 0.2 mole of cerium nitrate and dissolve them in 200 mL of water to form a second solution. Mix the first solution and the second solution to obtain a slurry, concentrate it at 70 °C, dry it at 100 °C for 12 h, and then calcine it at 300 °C for 2 h to obtain a solid precursor.

[0121] (2) The solid precursor was crushed, sieved through a 200-mesh sieve, and water and methylcellulose were added. The extruded strips were cut into Raschig rings with an outer diameter of 5 mm, an inner diameter of 3.5 mm, and a length of 4.5 mm. The strips were dried at 120°C for 3 h and calcined at 400°C for 2 h to obtain the shaped precursor.

[0122] (3) Weigh out 0.2 moles of bismuth nitrate equivalent to Bi and dissolve it in water to obtain a third solution. Impregnate the molding precursor with the third solution, bake at 90°C for 6 hours, and calcine at 550°C for 4 hours to obtain catalyst Bi. 0.2 / (MoFe 0.2 Co 0.7 Ni 0.2 Ce 0.2 K 0.04 )O j .

[0123] Table 1

[0124]

[0125] 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 catalyst has the general formula: Bi a / (MoFe) b X c Y d Z e )O j Where X is selected from at least one of Mg, Co, Ni, Ca, Cu, Zn, and Mn; Y is selected from at least one of La and Ce; Z is selected from at least one of K, Rb, Na, and Cs; a is the molar ratio of Bi to Mo, with a value of 0.1 to 0.3; b is the molar ratio of Fe to Mo, with a value of 0.1 to 0.5; c is the molar ratio of X to Mo, with a value of 0.5 to 1.5; d is the molar ratio of Y to Mo, with a value of 0.1 to 0.5; e is the molar ratio of Z to Mo, with a value of 0.01 to 0.06; j is the total number of oxygen atoms required to satisfy the valence of other elements; in the catalyst, the surface dispersion of Bi element is 1-3; 。 2. The oxidation catalyst according to claim 1, wherein, The surface dispersion of Bi element is 1.2-2.8; and / or The value of 'a' ranges from 0.15 to 0.2; and / or The value of b ranges from 0.15 to 0.3; and / or The value of c ranges from 0.7 to 1.2; and / or The value of d ranges from 0.15 to 0.3; and / or The value of e ranges from 0.02 to 0.

05.

3. The oxidation catalyst according to claim 1, wherein, X is selected from Co and Ni; and / or Y is selected from La and Ce.

4. A method for preparing an oxidation catalyst, characterized in that, The method includes: (1) Dissolve the Mo compound and Z compound in water to form a first solution; dissolve the Fe compound, X compound and Y compound in water to obtain a second solution; mix the first solution and the second solution to obtain a slurry, concentrate, dry and calcine to obtain a solid precursor; (2) The solid precursor is crushed, mixed with binder and water to form a shaped precursor, dried and calcined to obtain a shaped precursor; (3) Dissolve the Bi compound in an acidic solution to obtain a third solution, impregnate the third solution onto the molding precursor, and dry and calcine to obtain the catalyst; The feed amounts of each substance satisfy the general formula of the catalyst to be prepared: Bi a / (MoFe) b X c Y d Z e )O j Wherein, X is selected from at least one of Mg, Co, Ni, Ca, Cu, Zn, and Mn; Y is selected from at least one of La and Ce; Z is selected from at least one of K, Rb, Na, and Cs; a is the molar ratio of Bi to Mo, with a value of 0.1 to 0.3; b is the molar ratio of Fe to Mo, with a value of 0.1 to 0.5; c is the molar ratio of X to Mo, with a value of 0.5 to 1.5; d is the molar ratio of Y to Mo, with a value of 0.1 to 0.5; e is the molar ratio of Z to Mo, with a value of 0.01 to 0.06; j is the total number of oxygen atoms required to satisfy the valence of other elements; in the catalyst, the surface dispersion of Bi element is 1-3; .

5. The preparation method according to claim 4, wherein, In step (2), Solid precursors are broken down into particles smaller than 100 micrometers; and / or Drying conditions include: a temperature of 100-150℃; and / or a time of 1-4 hours; and / or The roasting conditions include: a temperature of 350-450℃; and / or a time of 1-3 hours.

6. The preparation method according to claim 4 or 5, wherein, In step (3), In acidic solutions, the mass concentration of the acid is 3wt-20wt%; and / or The impregnation method is equal volume impregnation; and / or Drying conditions include: a temperature of 80-100℃; and / or a time of 2-10 hours; and / or The roasting conditions include: a temperature of 500-600℃; and / or a time of 1-6 hours.

7. The preparation method according to claim 6, wherein, In the acidic solution, the acid is selected from nitric acid.

8. An oxidation catalyst prepared by the preparation method according to any one of claims 4-7.

9. The use of the oxidation catalyst according to any one of claims 1-3 or the oxidation catalyst according to claim 8 in the oxidation of olefins to prepare alkenal and / or alkenoic acids.

10. A method for selective oxidation of propylene, 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 1-3 or the oxidation catalyst according to claim 8.

11. The oxidation method according to claim 10, wherein, Exposure conditions include: The temperature is 300-550℃; The pressure is 0.01~0.08MPa, where the pressure is gauge pressure; The volumetric hourly space velocity (VHSV) of the feed gas is 1500–3000 mL / g•h; and / or By volume ratio, propylene : oxygen-containing oxidizing gas = 1 : (6-8).

12. The oxidation method according to claim 11, wherein, The temperature is 330-380℃.

13. The oxidation method according to claim 10, wherein, The raw material gas also contains diluent gaseous material; by volume ratio, propylene: diluent gaseous material = 1: (0.5~5), and the diluent gaseous material is water vapor.

14. The oxidation method according to claim 10, wherein, The oxygen-containing oxidizing gas is one or more of oxygen and air.

15. The oxidation method according to claim 10, wherein, The oxygen-containing oxidizing gas is air.

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