Preparation method and application of catalyst for preparing acrylic acid through selective oxidation of high-activity propylene or propane

Abstract

The invention provides a preparation method and application of a catalyst for preparing acrylic acid through selective oxidation of high-activity propylene or propane, and the preparation method comprises the following steps: uniformly mixing a molybdenum-vanadium-tellurium-niobium precursor, water and a pore-forming agent, washing, drying, roasting, and calcining to obtain a first oxide; the pore-forming agent is selected from one or more of ammonium citrate, ammonium carbonate, ammonium acetate and ammonium oxalate; mixing the molybdenum-vanadium-tellurium-niobium precursor with water, performing hydrothermal reaction, washing, drying, roasting, calcining, purifying, calcining and activating to obtain a second oxide; and mixing the first oxide and the second oxide to obtain the high-activity catalyst for preparing acrylic acid through selective oxidation of propylene or propane, namely the composite oxide catalyst. The composite oxide prepared by the method adopts a specific type of pore-forming agent, so that the reaction activity for preparing acrylic acid by selective oxidation of propylene or propane is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst preparation, and in particular relates to a preparation method and application of a high-activity catalyst for preparing acrylic acid by selective oxidation of propylene or propane. Background Art

[0002] Acrylic acid is a widely used monomer in the polymer field. It can be used as adhesives, pigments, super absorbent polymers, etc. At present, acrylic acid is mainly prepared by a two-step propylene process: first, propylene is selectively oxidized to acrolein at about 310°C under the catalysis of a Mo / Bi-based catalyst; then acrolein is selectively oxidized to acrylic acid at about 210°C under the catalysis of a Mo / V-based catalyst. The total conversion rate of propane in this process exceeds 90%, and the total selectivity of acrylic acid is also close to 90%. However, the two-step operation method is relatively complicated and the equipment investment cost is relatively high. Therefore, it is of great significance to prepare acrylic acid in a one-step process using propylene or propane as raw materials.

[0003] MoVTeNbOx mixed oxide is an excellent catalytic system for the selective oxidation of propylene or propane to acrylic acid in one step. Robert K. Grasselli et al. regulated the activity of the catalyst by incorporating P, W, B, and Cu elements during the synthesis process. Li Shuangming et al. also studied the regulatory effect of the incorporation of Cr, Fe, and Ce elements on the activity of the catalyst. Most of the MoVTeNbOx mixed oxide catalysts reported so far have a relatively low specific surface area, resulting in a relatively low activity of the catalyst. Therefore, it is necessary to further develop new synthesis methods to prepare catalysts with higher activity, thereby promoting the industrial application of the catalyst. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a method for preparing a high-activity catalyst for preparing acrylic acid by selective oxidation of propylene or propane and its application. The composite oxide catalyst prepared by the method adopts a specific type of pore-forming agent to obtain a higher specific surface area, thereby improving the reaction activity of preparing acrylic acid by selective oxidation of propylene or propane.

[0005] The present invention provides a method for preparing a high-activity catalyst for preparing acrylic acid by selective oxidation of propylene or propane, comprising the following steps:

[0006] The molybdenum-vanadium-tellurium-niobium precursor, water and a pore-forming agent are uniformly mixed, roasted and then calcined to obtain a first oxide; the pore-forming agent is selected from one or more of ammonium citrate, ammonium carbonate, ammonium acetate and ammonium oxalate;

[0007] The molybdenum, vanadium, tellurium and niobium precursors are mixed with water and subjected to hydrothermal reaction, washed and dried, roasted and then calcined, purified and calcined to activate, to obtain a second oxide;

[0008] The first oxide and the second oxide are mixed to obtain a high-activity catalyst for selective oxidation of propylene or propane to prepare acrylic acid.

[0009] Preferably, in the molybdenum-vanadium-tellurium-niobium precursor, Mo:V:Te:Nb=1:(0.2~0.4): (0.3~0.5): (0.10~0.2).

[0010] Preferably, the temperature for mixing the molybdenum-vanadium-tellurium-niobium precursor, water and the pore-forming agent is 0-120° C. and the time is 1-3 hours.

[0011] Preferably, the raw materials for preparing the molybdenum, vanadium, tellurium and niobium precursor include ammonium molybdate, ammonium niobium oxalate, telluric acid and vanadyl sulfate.

[0012] Preferably, the mass ratio of the pore-forming agent to ammonium molybdate is (1:40) to (1:1).

[0013] Preferably, the first oxide is prepared at a calcination temperature of 200-350° C. and a calcination time of 1-6 h;

[0014] The calcination temperature is 590~610℃, and the calcination time is 110~130min.

[0015] Preferably, the hydrothermal reaction temperature is 170-180° C., and the hydrothermal reaction time is 46-50 h.

[0016] Preferably, the second oxide is prepared by calcining at a temperature of 240-260° C. for a time of 1-6 h;

[0017] The calcination temperature is 590~610℃ and the calcination time is 110~130min.

[0018] Preferably, the mass ratio of the first oxide to the second oxide is (0.5:10) to (10:0.5).

[0019] The present invention provides a method for preparing acrylic acid by selective oxidation of propylene or propane, comprising the following steps:

[0020] The composite oxide catalyst prepared by the method described in the above technical solution is mixed with silicon carbide, and catalytically reacted in a mixed gas of propylene or propane, oxygen, argon and water vapor to obtain acrylic acid.

[0021] The present invention provides a method for preparing a catalyst for preparing acrylic acid by selective oxidation of propylene or propane with high activity, comprising the following steps: uniformly mixing a molybdenum, vanadium, tellurium, niobium precursor, water and a pore-forming agent, washing and drying, roasting and then calcining to obtain a first oxide; the pore-forming agent is selected from one or more of ammonium citrate, ammonium carbonate, ammonium acetate and ammonium oxalate; mixing the molybdenum, vanadium, tellurium, niobium precursor and water, hydrothermally reacting, washing and drying, roasting and then calcining, purifying and calcining and activating to obtain a second oxide; mixing the first oxide and the second oxide to obtain a catalyst for preparing acrylic acid by selective oxidation of propylene or propane with high activity, i.e., a composite oxide catalyst. The composite oxide catalyst prepared by the above method has a high specific surface area, thereby improving the reaction activity of preparing acrylic acid by selective oxidation of propylene or propane. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 N2 adsorption and desorption spectra of the catalysts prepared in Comparative Example 1 and Preparative Examples 1 to 5 of the present invention;

[0023] Figure 2 A is an electron microscope image of catalyst 1 prepared in comparative example 1, and B is an electron microscope image of the first oxide prepared in example 4. DETAILED DESCRIPTION

[0024] The present invention provides a method for preparing a high-activity catalyst for preparing acrylic acid by selective oxidation of propylene or propane, comprising the following steps:

[0025] The molybdenum-vanadium-tellurium-niobium precursor, water and a pore-forming agent are uniformly mixed, roasted and then calcined to obtain a first oxide; the pore-forming agent is selected from one or more of ammonium citrate, ammonium carbonate, ammonium acetate and ammonium oxalate;

[0026] The molybdenum, vanadium, tellurium and niobium precursors are mixed with water and subjected to hydrothermal reaction, washed and dried, roasted and then calcined, purified and calcined to activate, to obtain a second oxide;

[0027] The first oxide and the second oxide are mixed to obtain a high-activity catalyst for selective oxidation of propylene or propane to prepare acrylic acid.

[0028] The present invention mixes a molybdenum, vanadium, tellurium, and niobium precursor, water, and a pore-forming agent uniformly, and then calcines the mixture after roasting to obtain a first oxide. In the present invention, the molybdenum, vanadium, tellurium, and niobium precursor has Mo:V:Te:Nb=1:(0.2~0.4): (0.3~0.5): (0.10~0.2); in a specific embodiment, the molybdenum, vanadium, tellurium, and niobium precursor has Mo:V:Te:Nb=1:0.3:0.41:0.10. The raw materials used in the molybdenum, vanadium, and niobium precursor are ammonium molybdate, ammonium niobium oxalate, telluric acid, and vanadium oxysulfate.

[0029] The present invention preferably dissolves ammonium niobium oxalate, a raw material used in the molybdenum, vanadium, tellurium and niobium precursor, in water to obtain solution 1; then dissolves ammonium molybdate, vanadium oxysulfate and telluric acid in water to obtain solution 2; after mixing solution 1 and solution 2, a pore-forming agent is added, stirred until all the water evaporates, and then calcined.

[0030] The present invention specifically selects the type of pore-forming agent, which does not necessarily increase the reactive sites of the catalyst by increasing the specific surface area of ​​the oxide; the pore-forming agent in the present invention is one or more of ammonium citrate, ammonium carbonate, ammonium acetate and ammonium oxalate. The mass ratio of the pore-forming agent to ammonium molybdate is (1:40) to (1:1), preferably (1:20) to (1:1). In a specific embodiment, the mass ratio of the pore-forming agent to ammonium molybdate is 1:17.84.

[0031] The method of preparing the first oxide and drying after washing is a rotary evaporation method, a stirring method to dryness or an oven drying method. The temperature of mixing the molybdenum, vanadium, tellurium and niobium precursor, water and pore-forming agent in the present invention is 0-120°C, specifically 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C or 120°C; the molybdenum, vanadium, tellurium and niobium precursor, water and pore-forming agent are stirred evenly, preferably for 1-3h. To prepare a first oxide, the calcination temperature is 200-350°C, specifically 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, 320°C, 330°C, 340°C or 350°C; the calcination time is 1-6h, specifically 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h or 6h; the calcination temperature is 590-610°C, specifically 590°C, 600°C or 610°C; the calcination time is 110-130min, specifically 110min, 115 min, 120 min, 125 min or 130 min.

[0032] The invention comprises mixing a molybdenum, vanadium, tellurium and niobium precursor with water, performing a hydrothermal reaction, washing, drying, roasting and calcining, purifying and calcining and activating to obtain a second oxide.

[0033] In the present invention, the temperature of the hydrothermal reaction is 170-180°C, specifically 170°C, 175°C or 180°C; the time of the hydrothermal reaction is 46-50h, specifically 46h, 47h, 48h, 49h or 50h. The temperature used for roasting is 240-260°C, specifically 240°C, 250°C or 260°C; the time used for roasting is 1-6h, specifically 1h, 2h, 3h, 4h, 5h or 6h; the temperature of calcination is 590-610°C, specifically 590°C, 595°C, 600°C, 605°C or 610°C; the time of calcination is 110-130min, specifically 110min, 115min, 120min, 125min or 130min.

[0034] The present invention preferably uses hydrogen peroxide for purification. After purification, the temperature used for calcination activation is 590-610°C, specifically 590°C, 600°C or 610°C; the time is 110-130min, specifically 110min, 115min, 120min, 125min or 130min.

[0035] The feed ratio of the molybdenum, vanadium, tellurium, and niobium precursor used to prepare the first oxide and the molybdenum, vanadium, tellurium, and niobium precursor used to prepare the second oxide of the present invention can be the same or different; the processing methods can be the same or different.

[0036] After obtaining the first oxide and the second oxide, the present invention mixes the first oxide and the second oxide to obtain a composite oxide catalyst, that is, a high-activity catalyst for selectively oxidizing propylene or propane to prepare acrylic acid.

[0037] In the present invention, the mass ratio of the first oxide to the second oxide is (0.5:10) to (10:0.5), preferably (2-8):(8-2); more preferably (4-6):(6-4). In a specific embodiment, the mass ratio of the first oxide to the second oxide is 6:4.

[0038] The present invention provides a method for preparing acrylic acid by selective oxidation of propylene or propane, comprising the following steps:

[0039] The high-activity catalyst for preparing acrylic acid by selective oxidation of propylene or propane prepared by the method described in the above technical solution is mixed with silicon carbide, and catalytically reacted in a mixed gas of propylene or propane, oxygen, argon and water vapor to obtain acrylic acid.

[0040] The invention dilutes and mixes the high-activity propylene or propane selective oxidation catalyst for preparing acrylic acid with silicon carbide, places the mixture on a micro fixed bed reactor, and tests the catalytic activity at 280-380° C. The mass ratio of the composite catalyst to the mass ratio of silicon carbide is 1:1.

[0041] To further illustrate the present invention, the preparation method and application of a high-activity catalyst for selective oxidation of propylene or propane to prepare acrylic acid provided by the present invention are described in detail below in conjunction with examples, but they should not be construed as limiting the scope of protection of the present invention.

[0042] The reagents used in the following comparative examples and embodiments of the present invention, such as gases (propylene, oxygen, argon, etc.) and vanadyl sulfate, telluric acid, ammonium niobium oxalate, ammonium molybdate, ammonium citrate, ammonium carbonate, ammonium nitrate, ammonium acetate, ammonium oxalate, etc., were all purchased from the market.

[0043] Preparatory comparative example 1

[0044] The molar ratio of Mo:V:Te:Nb is 1:0.3:0.41:0.10. Under heating conditions at 80°C, 0.98g of ammonium niobium oxalate is weighed in proportion and dissolved in 25ml of ionized water to obtain solution 1. Similarly, 4.46g of ammonium molybdate, 1.95g of vanadyl sulfate, and 2.45g of telluric acid are weighed and dissolved in 50ml of deionized water to obtain solution 2. Solution 1 and solution 2 are mixed and stirred until the water is completely evaporated. The obtained precursor is placed in a muffle furnace and calcined at 300°C for 2h, and then calcined at 600°C for 2h under an argon atmosphere to obtain a second oxide, recorded as catalyst 1.

[0045] The catalytic performance test of the prepared catalyst 1 was carried out:

[0046] 600 mg of the above catalyst 1 was diluted and mixed with 600 mg of silicon carbide, placed in a micro fixed bed reactor, and the catalytic activity was tested at 280°C~380°C. The reaction gas composition was O2-C3H6-H2O-He=1-3.7-6.3-13, and the reaction gas space velocity was 2400 mL·h -1 ·g -1 When the reaction reaches a steady state, the tail gas after the reaction is analyzed online by SHIMADZU GC-2014 gas chromatograph. Porapak Q column and 5A molecular sieve column are connected to TCD detector for separation and analysis of CO, CO2, O2, aluminum oxide capillary column is connected to FID detector for separation and detection of hydrocarbons, and RTX-1 capillary column is connected to FID detector for separation and detection of oxygen-containing organic matter such as acrylic acid, acetic acid, etc. The specific catalytic activity is shown in Table 1, and the specific surface area is shown in Table 2.

[0047] Preparatory comparative example 2

[0048] The molar ratio of Mo:V:Te:Nb is 1:0.25:0.23:0.18. Under heating conditions at 80°C, 1.18g of ammonium niobium oxalate is weighed in proportion and dissolved in 25ml of ionized water to obtain solution 1. Similarly, 4.46g of ammonium molybdate, 1.63g of vanadyl sulfate, and 1.35g of telluric acid are weighed and dissolved in 50ml of deionized water to obtain solution 2. Solution 1 and solution 2 are mixed, and then hydroheated at 175°C for 48h. The hydroheated catalyst is then washed and dried, and the obtained precursor is placed in a muffle furnace and calcined at 250°C for 2h, and then calcined at 600°C for 2h in an argon atmosphere. The obtained catalyst is dissolved in hydrogen peroxide, washed and dried, and then calcined at 600°C for 2h in an argon atmosphere to obtain a second oxide, recorded as catalyst 2.

[0049] The catalytic performance of the prepared catalyst 2 was tested:

[0050] 600 mg of the above catalyst 2 was diluted and mixed with 600 mg of silicon carbide, placed in a micro fixed bed reactor, and the catalytic activity was tested at 280°C~380°C. The reaction gas composition was O2-C3H8-H2O-He=10%-5%-40%-45%, and the reaction gas space velocity was 2000 mL·h -1 ·g -1 When the reaction reached a steady state, the tail gas after the reaction was analyzed online by SHIMADZU GC-2014 gas chromatograph. Porapak Q column and 5A molecular sieve column were connected to TCD detector for separation and analysis of CO, CO2, O2, aluminum oxide capillary column was connected to FID detector for separation and detection of hydrocarbons, and RTX-1 capillary column was connected to FID detector for separation and detection of oxygen-containing organic matter such as acrylic acid, acetic acid, etc. The specific catalytic activity is shown in Table 3.

[0051] Preparatory comparative example 3

[0052] The molar ratio of Mo:V:Te:Nb is 1:0.3:0.41:0.10. Under heating conditions at 80°C, 0.98g of ammonium niobium oxalate is weighed in proportion and dissolved in 25ml of ionized water to obtain solution 1. Similarly, 4.46g of ammonium molybdate, 1.95g of vanadyl sulfate, and 2.45g of telluric acid are weighed and dissolved in 50ml of deionized water to obtain solution 2. Solution 1 and solution 2 are mixed and stirred evenly, and then 0.25g of ammonium nitrate is added and stirred until the water is completely evaporated. The obtained precursor is placed in a muffle furnace and calcined at 250°C for 2h, and then calcined at 600°C for 2h under an argon atmosphere to obtain a catalyst, i.e., the first oxide.

[0053] The catalytic performance of the prepared first oxide was tested:

[0054] 600 mg of the first oxide and 600 mg of silicon carbide were diluted and mixed, placed in a micro fixed bed reactor, and the catalytic activity was tested at 280°C~380°C. The reaction gas composition was O2-C3H6-H2O-He=1-3.7-6.3-13, and the reaction gas space velocity was 2400 mL·h -1 ·g -1 When the reaction reaches a steady state, the tail gas after the reaction is analyzed online by SHIMADZU GC-2014 gas chromatograph. Porapak Q column and 5A molecular sieve column are connected to TCD detector for separation and analysis of CO, CO2, O2, aluminum oxide capillary column is connected to FID detector for separation and detection of hydrocarbons, and RTX-1 capillary column is connected to FID detector for separation and detection of oxygen-containing organic matter such as acrylic acid and acetic acid. The specific catalytic activity is shown in Table 1, and the specific surface area is shown in Table 2.

[0055] Preliminary Example 1

[0056] The molar ratio of Mo:V:Te:Nb is 1:0.3:0.41:0.10. Under heating conditions at 80°C, 0.98g of ammonium niobium oxalate is weighed in proportion and dissolved in 25ml of ionized water to obtain solution 1. Similarly, 4.46g of ammonium molybdate, 1.95g of vanadyl sulfate, and 2.45g of telluric acid are weighed and dissolved in 50ml of deionized water to obtain solution 2. Solution 1 and solution 2 are mixed and stirred evenly, and then 0.25g of ammonium citrate is added and stirred until the water is completely evaporated. The obtained precursor is placed in a muffle furnace and calcined at 250°C for 2h, and then calcined at 600°C for 2h under an argon atmosphere to obtain a catalyst, i.e., the first oxide.

[0057] The catalytic performance of the prepared first oxide was tested:

[0058] 600 mg of the first oxide and 600 mg of silicon carbide were diluted and mixed, placed in a micro fixed bed reactor, and the catalytic activity was tested at 280°C~380°C. The reaction gas composition was O2-C3H6-H2O-He=1-3.7-6.3-13, and the reaction gas space velocity was 2400 mL·h -1 ·g -1 When the reaction reaches a steady state, the tail gas after the reaction is analyzed online by SHIMADZU GC-2014 gas chromatograph. Porapak Q column and 5A molecular sieve column are connected to TCD detector for separation and analysis of CO, CO2, O2, aluminum oxide capillary column is connected to FID detector for separation and detection of hydrocarbons, and RTX-1 capillary column is connected to FID detector for separation and detection of oxygen-containing organic matter such as acrylic acid, acetic acid, etc. The specific catalytic activity is shown in Table 1, and the specific surface area is shown in Table 2.

[0059] Preliminary Example 2

[0060] The molar ratio of Mo:V:Te:Nb is 1:0.3:0.41:0.10. Under heating conditions at 80°C, 0.98g of ammonium niobium oxalate is weighed in proportion and dissolved in 25ml of ionized water to obtain solution 1. Similarly, 4.46g of ammonium molybdate, 1.95g of vanadyl sulfate, and 2.45g of telluric acid are weighed and dissolved in 50ml of deionized water to obtain solution 2. Solution 1 and solution 2 are mixed and stirred evenly, and then 0.25g of ammonium acetate is added and stirred until the water is completely evaporated. The obtained precursor is placed in a muffle furnace and calcined at 250°C for 2h, and then calcined at 600°C for 2h under an argon atmosphere to obtain a catalyst, i.e., the first oxide.

[0061] The catalytic performance of the prepared first oxide was tested:

[0062] 600 mg of the first oxide and 600 mg of silicon carbide were diluted and mixed, placed in a micro fixed bed reactor, and the catalytic activity was tested at 280°C~380°C. The reaction gas composition was O2-C3H6-H2O-He=1-3.7-6.3-13, and the reaction gas space velocity was 2400 mL·h -1 ·g -1 When the reaction reaches a steady state, the tail gas after the reaction is analyzed online by SHIMADZU GC-2014 gas chromatograph. Porapak Q column and 5A molecular sieve column are connected to TCD detector for separation and analysis of CO, CO2, O2, aluminum oxide capillary column is connected to FID detector for separation and detection of hydrocarbons, and RTX-1 capillary column is connected to FID detector for separation and detection of oxygen-containing organic matter such as acrylic acid, acetic acid, etc. The specific catalytic activity is shown in Table 1, and the specific surface area is shown in Table 2.

[0063] Preparatory Example 3

[0064] The molar ratio of Mo:V:Te:Nb is 1:0.3:0.41:0.10. Under heating conditions at 80°C, 0.98g of ammonium niobium oxalate is weighed in proportion and dissolved in 25ml of ionized water to obtain solution 1. Similarly, 4.46g of ammonium molybdate, 1.95g of vanadyl sulfate, and 2.45g of telluric acid are weighed and dissolved in 50ml of deionized water to obtain solution 2. Solution 1 and solution 2 are mixed and stirred evenly, and then 0.25g of ammonium oxalate is added and stirred until the water is completely evaporated. The obtained precursor is placed in a muffle furnace and calcined at 250°C for 2h, and then calcined at 600°C for 2h under an argon atmosphere to obtain a catalyst, i.e., the first oxide.

[0065] The catalytic performance of the prepared first oxide was tested:

[0066] 600 mg of the first oxide and 600 mg of silicon carbide were diluted and mixed, placed in a micro fixed bed reactor, and the catalytic activity was tested at 280°C~380°C. The reaction gas composition was O2-C3H6-H2O-He=1-3.7-6.3-13, and the reaction gas space velocity was 2400 mL·h -1 ·g -1 When the reaction reaches a steady state, the tail gas after the reaction is analyzed online by SHIMADZU GC-2014 gas chromatograph. Porapak Q column and 5A molecular sieve column are connected to TCD detector for separation and analysis of CO, CO2, O2, aluminum oxide capillary column is connected to FID detector for separation and detection of hydrocarbons, and RTX-1 capillary column is connected to FID detector for separation and detection of oxygen-containing organic matter such as acrylic acid, acetic acid, etc. The specific catalytic activity is shown in Table 1, and the specific surface area is shown in Table 2.

[0067] Preliminary Example 4

[0068] The molar ratio of Mo:V:Te:Nb is 1:0.3:0.41:0.10. Under heating conditions at 80°C, 0.98g of ammonium niobium oxalate is weighed in proportion and dissolved in 25ml of ionized water to obtain solution 1; similarly, 4.46g of ammonium molybdate, 1.95g of vanadyl sulfate, and 2.45g of telluric acid are weighed and dissolved in 50ml of deionized water to obtain solution 2; solution 1 and solution 2 are mixed and stirred evenly, and then 0.25g of ammonium oxalate is added and stirred evenly, and then a rotary evaporator is used to remove all water, and then the obtained precursor is placed in a muffle furnace and calcined at 250°C for 2h, and then calcined at 600°C for 2h under an argon atmosphere to obtain a catalyst, i.e., the first oxide.

[0069] The catalytic performance of the prepared first oxide was tested:

[0070] 600 mg of the above catalyst was diluted and mixed with 600 mg of silicon carbide, placed in a micro fixed bed reactor, and the catalytic activity was tested at 280°C~380°C. The reaction gas composition was O2-C3H6-H2O-He=1-3.7-6.3-13, and the reaction gas space velocity was 2400 mL·h -1 ·g -1 When the reaction reaches a steady state, the tail gas after the reaction is analyzed online by SHIMADZU GC-2014 gas chromatograph. Porapak Q column and 5A molecular sieve column are connected to TCD detector for separation and analysis of CO, CO2, O2, aluminum oxide capillary column is connected to FID detector for separation and detection of hydrocarbons, and RTX-1 capillary column is connected to FID detector for separation and detection of oxygen-containing organic matter such as acrylic acid, acetic acid, etc. The specific catalytic activity is shown in Table 1, and the specific surface area is shown in Table 2.

[0071] Preliminary Example 5

[0072] The molar ratio of Mo:V:Te:Nb is 1:0.3:0.41:0.10. Under heating conditions at 80°C, 0.98g of ammonium niobium oxalate is weighed in proportion and dissolved in 25ml of ionized water to obtain solution 1; 4.46g of ammonium molybdate, 1.95g of vanadyl sulfate, and 2.45g of telluric acid are also weighed and dissolved in 50ml of deionized water to obtain solution 2; solution 1 and solution 2 are mixed and stirred evenly, and then 0.25g of ammonium oxalate is added and stirred evenly, and then a rotary evaporator is used to remove all water, and then the obtained precursor is placed in a muffle furnace, roasted at 300°C for 2h, and then calcined at 600°C for 2h under an argon atmosphere to obtain a catalyst, i.e., the first oxide.

[0073] The catalytic performance of the prepared first oxide was tested:

[0074] 600 mg of the first oxide and 600 mg of silicon carbide were diluted and mixed, placed in a micro fixed bed reactor, and the catalytic activity was tested at 280°C~380°C. The reaction gas composition was O2-C3H6-H2O-He=1-3.7-6.3-13, and the reaction gas space velocity was 2400 mL·h -1 ·g -1 When the reaction reaches a steady state, the tail gas after the reaction is analyzed online by SHIMADZU GC-2014 gas chromatograph. Porapak Q column and 5A molecular sieve column are connected to TCD detector for separation and analysis of CO, CO2, O2, aluminum oxide capillary column is connected to FID detector for separation and detection of hydrocarbons, and RTX-1 capillary column is connected to FID detector for separation and detection of oxygen-containing organic matter such as acrylic acid, acetic acid, etc. The specific catalytic activity is shown in Table 1, and the specific surface area is shown in Table 2.

[0075] Comparative Example 1

[0076] The catalysts in Preparatory Comparative Example 1 and Preparatory Comparative Example 2 were mixed in a mass ratio of 6:4, and then the mixture was ground and mixed evenly in an agate mortar to obtain Comparative Catalyst 1.

[0077] The catalytic performance test of the prepared comparative catalyst 1 was carried out:

[0078] 600 mg of the above-mentioned comparative catalyst 1 was diluted and mixed with 600 mg of silicon carbide, placed in a micro fixed bed reactor, and the catalytic activity was tested at 280°C~380°C. The reaction gas composition was O2-C3H8-H2O-He=10%-5%-40%-45%, and the reaction gas space velocity was 2000 mL·h -1 ·g -1When the reaction reached a steady state, the tail gas after the reaction was analyzed online by SHIMADZU GC-2014 gas chromatograph. Porapak Q column and 5A molecular sieve column were connected to TCD detector for separation and analysis of CO, CO2, O2, aluminum oxide capillary column was connected to FID detector for separation and detection of hydrocarbons, and RTX-1 capillary column was connected to FID detector for separation and detection of oxygen-containing organic matter such as acrylic acid, acetic acid, etc. The specific catalytic activity is shown in Table 3.

[0079] Comparative Example 2

[0080] The catalysts in Preparatory Comparative Example 1 and Preparatory Comparative Example 2 were mixed in a mass ratio of 6:4, and then the mixture was placed in a QM-3SP2 star ball mill for grinding and mixing to obtain a comparative catalyst 2.

[0081] The catalytic performance test of the prepared comparative catalyst 2 was carried out:

[0082] 600 mg of the above-mentioned comparative catalyst 2 was diluted and mixed with 600 mg of silicon carbide, placed in a micro fixed bed reactor, and the catalytic activity was tested at 280°C~380°C. The reaction gas composition was O2-C3H8-H2O-He=10%-5%-40%-45%, and the reaction gas space velocity was 2000 mL·h -1 ·g -1 When the reaction reached a steady state, the tail gas after the reaction was analyzed online by SHIMADZU GC-2014 gas chromatograph. Porapak Q column and 5A molecular sieve column were connected to TCD detector for separation and analysis of CO, CO2, O2, aluminum oxide capillary column was connected to FID detector for separation and detection of hydrocarbons, and RTX-1 capillary column was connected to FID detector for separation and detection of oxygen-containing organic matter such as acrylic acid, acetic acid, etc. The specific catalytic activity is shown in Table 3.

[0083] Comparative Example 3

[0084] The catalysts in Preparatory Comparative Example 3 and Preparatory Comparative Example 2 were mixed in a mass ratio of 6:4, and then the mixture was placed in an agate mortar and ground and mixed evenly to obtain Comparative Catalyst 3.

[0085] The catalytic performance test of the prepared comparative catalyst 3 was carried out:

[0086] 600 mg of the above-mentioned comparative catalyst 1 was diluted and mixed with 600 mg of silicon carbide, placed in a micro fixed bed reactor, and the catalytic activity was tested at 280°C~380°C. The reaction gas composition was O2-C3H8-H2O-He=10%-5%-40%-45%, and the reaction gas space velocity was 2000 mL·h -1 ·g -1When the reaction reached a steady state, the tail gas after the reaction was analyzed online by SHIMADZU GC-2014 gas chromatograph. Porapak Q column and 5A molecular sieve column were connected to TCD detector for separation and analysis of CO, CO2, O2, aluminum oxide capillary column was connected to FID detector for separation and detection of hydrocarbons, and RTX-1 capillary column was connected to FID detector for separation and detection of oxygen-containing organic matter such as acrylic acid, acetic acid, etc. The specific catalytic activity is shown in Table 3.

[0087] Example 1

[0088] The catalysts in Preparatory Example 1 and Preparatory Comparative Example 2 were mixed in a mass ratio of 6:4, and then the mixture was placed in an agate mortar and ground and mixed uniformly to obtain a composite oxide catalyst.

[0089] The catalytic performance of the prepared composite oxide catalyst was tested:

[0090] 600 mg of the above composite oxide catalyst was diluted and mixed with 600 mg of silicon carbide, placed in a micro fixed bed reactor, and the catalytic activity was tested at 280°C~380°C. The reaction gas composition was O2-C3H8-H2O-He=10%-5%-40%-45%, and the reaction gas space velocity was 2000 mL·h -1 ·g -1 When the reaction reached a steady state, the tail gas after the reaction was analyzed online by SHIMADZU GC-2014 gas chromatograph. Porapak Q column and 5A molecular sieve column were connected to TCD detector for separation and analysis of CO, CO2, O2, aluminum oxide capillary column was connected to FID detector for separation and detection of hydrocarbons, and RTX-1 capillary column was connected to FID detector for separation and detection of oxygen-containing organic matter such as acrylic acid, acetic acid, etc. The specific catalytic activity is shown in Table 3.

[0091] Example 2

[0092] The catalysts in Preparatory Example 2 and Preparatory Comparative Example 2 were mixed in a mass ratio of 6:4, and then the mixture was placed in an agate mortar and ground and mixed uniformly to obtain a composite oxide catalyst.

[0093] The catalytic performance of the prepared composite oxide catalyst was tested:

[0094] 600 mg of the above composite oxide catalyst was diluted and mixed with 600 mg of silicon carbide, placed in a micro fixed bed reactor, and the catalytic activity was tested at 280°C~380°C. The reaction gas composition was O2-C3H8-H2O-He=10%-5%-40%-45%, and the reaction gas space velocity was 2000 mL·h -1 ·g -1When the reaction reached a steady state, the tail gas after the reaction was analyzed online by SHIMADZU GC-2014 gas chromatograph. Porapak Q column and 5A molecular sieve column were connected to TCD detector for separation and analysis of CO, CO2, O2, aluminum oxide capillary column was connected to FID detector for separation and detection of hydrocarbons, and RTX-1 capillary column was connected to FID detector for separation and detection of oxygen-containing organic matter such as acrylic acid, acetic acid, etc. The specific catalytic activity is shown in Table 3.

[0095] Example 3

[0096] The catalysts in Preparatory Example 3 and Preparatory Comparative Example 2 were mixed in a mass ratio of 6:4, and then the mixture was ground and mixed evenly in an agate mortar to obtain a composite oxide catalyst.

[0097] The present invention conducts catalytic performance tests on the prepared composite oxide catalyst:

[0098] 600 mg of the above composite oxide catalyst was diluted and mixed with 600 mg of silicon carbide, placed in a micro fixed bed reactor, and the catalytic activity was tested at 280°C~380°C. The reaction gas composition was O2-C3H8-H2O-He=10%-5%-40%-45%, and the reaction gas space velocity was 2000 mL·h -1 ·g -1 When the reaction reached a steady state, the tail gas after the reaction was analyzed online by SHIMADZU GC-2014 gas chromatograph. Porapak Q column and 5A molecular sieve column were connected to TCD detector for separation and analysis of CO, CO2, O2, aluminum oxide capillary column was connected to FID detector for separation and detection of hydrocarbons, and RTX-1 capillary column was connected to FID detector for separation and detection of oxygen-containing organic matter such as acrylic acid, acetic acid, etc. The specific catalytic activity is shown in Table 3.

[0099] Example 4

[0100] The catalysts in Preparatory Example 4 and Preparatory Comparative Example 2 were mixed in a mass ratio of 6:4, and then the mixture was placed in an agate mortar and ground and mixed uniformly to obtain a composite oxide catalyst.

[0101] The catalytic performance of the prepared composite oxide catalyst was tested:

[0102] 600 mg of the above composite oxide catalyst was diluted and mixed with 600 mg of silicon carbide, placed in a micro fixed bed reactor, and the catalytic activity was tested at 280°C~380°C. The reaction gas composition was O2-C3H8-H2O-He=10%-5%-40%-45%, and the reaction gas space velocity was 2000 mL·h -1 ·g -1When the reaction reached a steady state, the tail gas after the reaction was analyzed online by SHIMADZU GC-2014 gas chromatograph. Porapak Q column and 5A molecular sieve column were connected to TCD detector for separation and analysis of CO, CO2, O2, aluminum oxide capillary column was connected to FID detector for separation and detection of hydrocarbons, and RTX-1 capillary column was connected to FID detector for separation and detection of oxygen-containing organic matter such as acrylic acid, acetic acid, etc. The specific catalytic activity is shown in Table 3.

[0103] Example 5

[0104] The catalysts in Preparatory Example 5 and Preparatory Comparative Example 2 were mixed in a mass ratio of 6:4, and then the mixture was placed in an agate mortar and ground and mixed uniformly to obtain a composite oxide catalyst.

[0105] The catalytic performance of the prepared composite oxide catalyst was tested:

[0106] 600 mg of the above composite oxide catalyst was diluted and mixed with 600 mg of silicon carbide, placed in a micro fixed bed reactor, and the catalytic activity was tested at 280°C~380°C. The reaction gas composition was O2-C3H8-H2O-He=10%-5%-40%-45%, and the reaction gas space velocity was 2000 mL·h -1 ·g -1 When the reaction reached a steady state, the tail gas after the reaction was analyzed online by SHIMADZU GC-2014 gas chromatograph. Porapak Q column and 5A molecular sieve column were connected to TCD detector for separation and analysis of CO, CO2, O2, aluminum oxide capillary column was connected to FID detector for separation and detection of hydrocarbons, and RTX-1 capillary column was connected to FID detector for separation and detection of oxygen-containing organic matter such as acrylic acid, acetic acid, etc. The specific catalytic activity is shown in Table 3.

[0107] Table 1

[0108]

[0109] Table 2

[0110]

[0111] Table 3

[0112]

[0113] As can be seen from the above embodiments, the present invention provides a method for preparing a catalyst for preparing acrylic acid by selective oxidation of propylene or propane with high activity, comprising the following steps: uniformly mixing a molybdenum, vanadium, tellurium, niobium precursor, water and a pore-forming agent, washing and drying, roasting and then calcining to obtain a first oxide; the pore-forming agent is selected from one or more of ammonium citrate, ammonium carbonate, ammonium acetate and ammonium oxalate; mixing the molybdenum, vanadium, tellurium, niobium precursor and water, hydrothermally reacting, washing and drying, roasting and then calcining, purifying and calcining and activating to obtain a second oxide; mixing the first oxide and the second oxide to obtain a composite oxide catalyst, i.e., a catalyst for preparing acrylic acid by selective oxidation of propylene or propane with high activity. The composite oxide prepared by the above method has a high specific surface area, thereby improving the reaction activity of preparing acrylic acid by selective oxidation of propylene or propane. The experimental results show that the propane conversion rate of the catalyst with the best performance catalyzing the selective oxidation of propane to prepare acrylic acid is 75.2%, and the acrylic acid selectivity is 75.6%.

[0114] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a high-activity catalyst for preparing acrylic acid by selective oxidation of propylene or propane, comprising the following steps: The molybdenum-vanadium-tellurium-niobium precursor, water and a pore-forming agent are uniformly mixed, roasted and then calcined to obtain a first oxide; the pore-forming agent is selected from one or more of ammonium citrate, ammonium carbonate, ammonium acetate and ammonium oxalate; The molybdenum, vanadium, tellurium and niobium precursors are mixed with water and subjected to hydrothermal reaction, washed and dried, roasted and then calcined, purified and calcined to activate, to obtain a second oxide; The first oxide and the second oxide are mixed to obtain a high-activity catalyst for selective oxidation of propylene or propane to prepare acrylic acid.

2. The preparation method according to claim 1, characterized in that: In the molybdenum-vanadium-tellurium-niobium precursor, Mo:V:Te:Nb=1:(0.2~0.4): (0.3~0.5): (0.10~0.2).

3. The preparation method according to claim 1, characterized in that: The temperature of mixing the molybdenum, vanadium, tellurium and niobium precursor, water and pore-forming agent used in preparing the first oxide is 0-120° C. and the time is 1-3 hours.

4. The preparation method according to claim 1, characterized in that: The raw materials for preparing the molybdenum-vanadium-tellurium-niobium precursor include ammonium molybdate, ammonium niobium oxalate, telluric acid and vanadium oxysulfate.

5. The preparation method according to claim 4, characterized in that: The mass ratio of the pore former to ammonium molybdate is (1:40) to (1:1).

6. The preparation method according to claim 1, characterized in that: Prepare the first oxide, the calcination temperature is 200-350°C, and the calcination time is 1-6 hours; The calcination temperature is 590~610℃, and the calcination time is 110~130min.

7. The preparation method according to claim 1, characterized in that: The hydrothermal reaction temperature is 170~180°C, and the hydrothermal reaction time is 46~50h.

8. The preparation method according to claim 1, characterized in that: Prepare the second oxide, the calcination temperature is 240~260℃, the time is 1~6h; The calcination temperature is 590~610℃ and the calcination time is 110~130min.

9. The preparation method according to claim 1, characterized in that: The mass ratio of the first oxide to the second oxide is (0.5:10) to (10:0.5).

10. A method for preparing acrylic acid by selective oxidation of propylene or propane, comprising the following steps: The high-activity catalyst for preparing acrylic acid by selective oxidation of propylene or propane prepared by the method according to any one of claims 1 to 9 is mixed with silicon carbide, and catalytically reacted in a mixed gas of propylene or propane, oxygen, argon and water vapor to obtain acrylic acid.

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