Preparation method and application of a catalyst for selectively oxidizing propylene or propane with high activity to prepare acrylic acid

Abstract

The present invention provides a preparation method and application of a catalyst for the selective oxidation of high-activity propylene or propane to prepare acrylic acid, comprising the following steps: mixing a molybdenum-vanadium-tellurium-niobium precursor, water and a pore-forming agent evenly, washing and then 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 and then carrying out a hydrothermal reaction, washing and then drying, roasting and then calcining, and then purifying and calcining and activating to obtain a second oxide; mixing the first oxide and the second oxide to obtain a catalyst for the selective oxidation of high-activity propylene or propane to prepare acrylic acid, namely a composite oxide catalyst. The composite oxide prepared by the above method adopts a specific type of pore-forming agent, thereby improving the reaction activity of the selective oxidation of propylene or propane to prepare acrylic acid.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalyst preparation, and particularly relates to a preparation method and application of a catalyst for selectively oxidizing high-activity propylene or propane to prepare acrylic acid. Background Art

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

[0003] The MoVTeNbOx mixed oxide is an excellent catalytic system for selectively oxidizing propylene or propane to acrylic acid in one step. Robert K. Grasselli et al. adjusted the catalyst activity by incorporating elements such as P, W, B, and Cu during the synthesis process, and Li Shuangming et al. also studied the regulation effect of the incorporation of elements such as Cr, Fe, and Ce on the catalyst activity. At present, most of the reported MoVTeNbOx mixed oxide catalysts have a relatively low specific surface area, resulting in relatively low activity of the catalysts. Therefore, it is necessary to further develop new synthesis methods to prepare catalysts with higher activity, so as to promote the industrial application of this catalyst. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a preparation method and application of a catalyst for selectively oxidizing high-activity propylene or propane to prepare acrylic acid. The composite oxide catalyst prepared by this method uses a specific type of pore-forming agent to obtain a higher specific surface area, thereby improving the reaction activity of selectively oxidizing propylene or propane to prepare acrylic acid.

[0005] The present invention provides a preparation method of a catalyst for selectively oxidizing high-activity propylene or propane to prepare acrylic acid, comprising the following steps:

[0006] Mix the molybdenum-vanadium-tellurium-niobium precursor, water and a pore-forming agent evenly, calcine and then sinter, 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] Mix the molybdenum-vanadium-tellurium-niobium precursor and water, carry out a hydrothermal reaction, wash and then dry, calcine and then sinter, and then purify and sinter for activation to obtain a second oxide;

[0008] Mix the first oxide and the second oxide to obtain a catalyst for the selective oxidation of high-activity 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 h.

[0011] Preferably, the raw materials for preparing the molybdenum-vanadium-tellurium-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) - (1:1).

[0013] Preferably, for preparing the first oxide, the calcination temperature is 200 - 350 °C, and the calcination time is 1 - 6 h;

[0014] The roasting temperature is 590 - 610 °C, and the roasting time is 110 - 130 min.

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

[0016] Preferably, for preparing the second oxide, the calcination temperature is 240 - 260 °C, and the time is 1 - 6 h;

[0017] The roasting temperature is 590 - 610 °C, and the time is 110 - 130 min.

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

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

[0020] Mix the composite oxide catalyst prepared by the method described in the above technical solution with silicon carbide, and carry out a catalytic reaction 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 the selective oxidation of high-activity propylene or propane to acrylic acid, comprising the following steps: mixing a molybdenum-vanadium-tellurium-niobium precursor, water and a pore-forming agent uniformly, washing and then 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 and then carrying out a hydrothermal reaction, washing and then drying, roasting and then calcining, and then purifying and calcining for activation to obtain a second oxide; mixing the first oxide and the second oxide to obtain a catalyst for the selective oxidation of high-activity propylene or propane to acrylic acid, i.e., a composite oxide catalyst. The composite oxide catalyst prepared by the above method has a relatively high specific surface area, thereby improving the reaction activity of the selective oxidation of propylene or propane to acrylic acid. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is the N2 adsorption and desorption spectrogram of the catalysts prepared in Preparation Comparative Example 1 and Preparation Examples 1-5 of the present invention;

[0023] Figure 2 In it, A is the electron micrograph of Catalyst 1 prepared in Preparation Comparative Example 1, and B is the electron micrograph of the first oxide prepared in Preparation Example 4. DETAILED DESCRIPTION OF THE INVENTION

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

[0025] Mixing a molybdenum-vanadium-tellurium-niobium precursor, water and a pore-forming agent uniformly, 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;

[0026] Mixing the molybdenum-vanadium-tellurium-niobium precursor and water and then carrying out a hydrothermal reaction, washing and then drying, roasting and then calcining, and then purifying and calcining for activation to obtain a second oxide;

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

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

[0029] In the present invention, ammonium niobium oxalate, which is the raw material used for the molybdenum-vanadium-tellurium-niobium precursor, is preferably dissolved in water to obtain Solution 1; then ammonium molybdate, vanadyl sulfate and tellurous acid are dissolved in water to obtain Solution 2; after mixing Solution 1 and Solution 2, a pore-forming agent is added, and the mixture is stirred until all the water has evaporated, and then calcined.

[0030] In the present invention, a specific selection is made for the type of pore-forming agent. It is not that as long as the specific surface area of the oxide can be increased, the reaction active sites of the catalyst can necessarily be increased; in the present invention, the pore-forming agent 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 example, the mass ratio of the pore-forming agent to ammonium molybdate is 1:17.84.

[0031] The method for preparing the first oxide and drying it after washing is rotary evaporation drying, stirring to dryness or oven drying. In the present invention, the temperature for mixing the molybdenum-vanadium-tellurium-niobium precursor, water and the pore-forming agent is 0 to 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-niobium precursor, water and the pore-forming agent are stirred evenly, and the stirring time is preferably 1 to 3 h. When preparing the first oxide, the calcination temperature is 200 to 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 to 6 h, specifically 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h or 6 h; the calcination temperature is 590 to 610 °C, specifically 590 °C, 600 °C or 610 °C; the calcination time is 110 to 130 min, specifically 110 min, 115 min, 120 min, 125 min or 130 min.

[0032] In the present invention, the molybdenum-vanadium-tellurium-niobium precursor and water are mixed and then subjected to hydrothermal reaction, washed and dried, calcined and then calcined again, and then purified and calcined for activation to obtain the 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 - 50 h, specifically 46 h, 47 h, 48 h, 49 h or 50 h. The temperature used for calcination is 240 - 260 °C, specifically 240 °C, 250 °C or 260 °C; the time used for calcination is 1 - 6 h, specifically 1 h, 2 h, 3 h, 4 h, 5 h or 6 h; 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 - 130 min, specifically 110 min, 115 min, 120 min, 125 min or 130 min.

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

[0035] The feeding ratio of the molybdenum - vanadium - tellurium - niobium precursor used for preparing the first oxide and the molybdenum - vanadium - tellurium - niobium precursor used for preparing the second oxide in the present invention can be the same or different; the treatment 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 catalyst for the selective oxidation of high - activity 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) - (10:0.5), preferably (2 - 8):(8 - 2); more preferably (4 - 6):(6 - 4). In specific examples, the mass ratio of the first oxide to the second oxide is 6:4.

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

[0039] Mix the catalyst for the selective oxidation of high - activity propylene or propane to prepare acrylic acid prepared by the method of the above - mentioned technical solution with silicon carbide, and carry out a catalytic reaction in a mixed gas of propylene or propane, oxygen, argon and water vapor to obtain acrylic acid.

[0040] After diluting and mixing the catalyst for the selective oxidation of high - activity propylene or propane to prepare acrylic acid with silicon carbide, the present invention places it 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 of silicon carbide is 1:1.

[0041] To further illustrate the present invention, the preparation method and application of a catalyst for selectively oxidizing high-activity propylene or propane to prepare acrylic acid provided by the present invention will be described in detail below in conjunction with embodiments, 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 examples of the present invention, such as gases (propylene, oxygen, argon, etc.) and reagents such as 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] Preliminary Comparative Example 1

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

[0045] The catalytic performance of the prepared Catalyst 1 was tested:

[0046] After mixing 600 mg of the above-mentioned Catalyst 1 with 600 mg of silicon carbide for dilution, it was placed on a micro fixed-bed reactor, and the catalytic activity was tested at 280 °C to 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 reached a steady state, the tail gas after the reaction was analyzed online by SHIMADZU GC-2014 gas chromatography. The Porapak Q column and 5A molecular sieve column were connected to the TCD detector for separating and analyzing CO, CO2, and O2, the alumina capillary column was connected to the FID detector for separating and detecting hydrocarbons, and the RTX-1 capillary column was connected to the FID detector for separating and detecting oxygen-containing organic compounds 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.

[0047] Preliminary Comparative Example 2

[0048] The molar ratio of Mo:V:Te:Nb is 1:0.25:0.23:0.18. Under the heating condition of 80 °C, 1.18 g of ammonium niobium oxalate was weighed proportionally and dissolved in 25 ml of ionized water to obtain Solution 1. Similarly, 4.46 g of ammonium molybdate, 1.63 g of vanadyl sulfate, and 1.35 g of telluric acid were weighed and dissolved in 50 ml of deionized water to obtain Solution 2. After mixing Solution 1 and Solution 2, it was then hydrothermally treated at 175 °C for 48 h. Then, the hydrothermally treated catalyst was washed and dried, and the obtained precursor was placed in a muffle furnace and calcined at 250 °C for 2 h. Subsequently, it was calcined at 600 °C for 2 h under an argon atmosphere. The obtained catalyst was dissolved in hydrogen peroxide, washed, dried, and then calcined at 600 °C for 2 h under an argon atmosphere to obtain the second oxide, denoted as Catalyst 2.

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

[0050] After mixing 600 mg of the above-mentioned Catalyst 2 with 600 mg of silicon carbide and diluting, it was placed on 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 chromatography. The Porapak Q column and 5A molecular sieve column were connected to the TCD detector for the separation and analysis of CO, CO2, and O2. The alumina capillary column was connected to the FID detector for the separation and detection of hydrocarbons. The RTX-1 capillary column was connected to the FID detector for the separation and detection of oxygen-containing organic compounds such as acrylic acid and acetic acid. 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 the heating condition of 80 °C, 0.98 g of ammonium niobium oxalate was weighed proportionally and dissolved in 25 ml of ionized water to obtain Solution 1; similarly, 4.46 g of ammonium molybdate, 1.95 g of vanadyl sulfate, and 2.45 g of telluric acid were weighed and dissolved in 50 ml of deionized water to obtain Solution 2; after mixing Solution 1 and Solution 2 and stirring evenly, 0.25 g of ammonium nitrate was added and stirred until the water was completely evaporated. The obtained precursor was placed in a muffle furnace and calcined at 250 °C for 2 h. Subsequently, it was calcined at 600 °C for 2 h under an argon atmosphere to obtain the catalyst, i.e., the first oxide.

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

[0054] After diluting and mixing 600 mg of the above-mentioned first oxide with 600 mg of silicon carbide, it was placed on a micro fixed-bed reactor, and the catalytic activity was tested at 280 °C to 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 . After the reaction reached a steady state, the tail gas after the reaction was analyzed online by SHIMADZU GC-2014 gas chromatography. The Porapak Q column and 5A molecular sieve column were connected to the TCD detector for separating and analyzing CO, CO2, and O2. The alumina capillary column was connected to the FID detector for separating and detecting hydrocarbons. The RTX-1 capillary column was connected to the FID detector for separating and detecting oxygen-containing organic compounds 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 was 1:0.3:0.41:0.10. Under the heating condition of 80 °C, 0.98 g of ammonium niobium oxalate was weighed and dissolved in 25 ml of ionized water to obtain Solution 1. Similarly, 4.46 g of ammonium molybdate, 1.95 g of vanadyl sulfate, and 2.45 g of telluric acid were weighed and dissolved in 50 ml of deionized water to obtain Solution 2. After mixing Solution 1 and Solution 2 and stirring evenly, 0.25 g of ammonium citrate was added and stirred until the water was completely evaporated. The obtained precursor was placed in a muffle furnace and calcined at 250 °C for 2 h, and then calcined at 600 °C for 2 h in an argon atmosphere to obtain a catalyst, that is, the first oxide.

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

[0058] After diluting and mixing 600 mg of the above-mentioned first oxide with 600 mg of silicon carbide, it was placed on a micro fixed-bed reactor, and the catalytic activity was tested at 280 °C to 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 . After the reaction reached a steady state, the tail gas after the reaction was analyzed online by SHIMADZU GC-2014 gas chromatography. The Porapak Q column and 5A molecular sieve column were connected to the TCD detector for separating and analyzing CO, CO2, and O2. The alumina capillary column was connected to the FID detector for separating and detecting hydrocarbons. The RTX-1 capillary column was connected to the FID detector for separating and detecting oxygen-containing organic compounds 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.

[0059] Preliminary Example 2

[0060] The molar ratio of Mo:V:Te:Nb is 1:0.3:0.41:0.10. Under the heating condition of 80 °C, 0.98 g of ammonium niobium oxalate is weighed proportionally and dissolved in 25 ml of ionized water to obtain Solution 1; similarly, 4.46 g of ammonium molybdate, 1.95 g of vanadyl sulfate, and 2.45 g of telluric acid are weighed and dissolved in 50 ml of deionized water to obtain Solution 2; Solution 1 and Solution 2 are mixed and stirred evenly, then 0.25 g 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 2 h, and then calcined at 600 °C for 2 h in an argon atmosphere to obtain a catalyst, namely the first oxide.

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

[0062] After mixing 600 mg of the above-mentioned first oxide with 600 mg of silicon carbide for dilution, it is placed on a micro fixed-bed reactor, and the catalytic activity is tested at 280 °C to 380 °C. The reaction gas composition is O2-C3H6-H2O-He = 1-3.7-6.3-13, and the reaction gas space velocity is 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 chromatography. The Porapak Q column and 5A molecular sieve column are connected to the TCD detector for separating and analyzing CO, CO2, and O2, the alumina capillary column is connected to the FID detector for separating and detecting hydrocarbons, and the RTX-1 capillary column is connected to the FID detector for separating and detecting oxygen-containing organic compounds 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.

[0063] Preparation Example 3

[0064] The molar ratio of Mo:V:Te:Nb is 1:0.3:0.41:0.10. Under the heating condition of 80 °C, 0.98 g of ammonium niobium oxalate is weighed proportionally and dissolved in 25 ml of ionized water to obtain Solution 1; similarly, 4.46 g of ammonium molybdate, 1.95 g of vanadyl sulfate, and 2.45 g of telluric acid are weighed and dissolved in 50 ml of deionized water to obtain Solution 2; Solution 1 and Solution 2 are mixed and stirred evenly, then 0.25 g 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 2 h, and then calcined at 600 °C for 2 h in an argon atmosphere to obtain a catalyst, namely the first oxide.

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

[0066] After diluting and mixing 600 mg of the above-mentioned first oxide with 600 mg of silicon carbide, it was placed on a micro fixed-bed reactor, and the catalytic activity was tested at 280 °C to 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 After the reaction reached a steady state, the tail gas after the reaction was analyzed online by SHIMADZU GC-2014 gas chromatography. The Porapak Q column and 5A molecular sieve column were connected to the TCD detector for separating and analyzing CO, CO2, and O2. The alumina capillary column was connected to the FID detector for separating and detecting hydrocarbons. The RTX-1 capillary column was connected to the FID detector for separating and detecting oxygen-containing organic compounds 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.

[0067] Preliminary Example 4

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

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

[0070] After diluting and mixing 600 mg of the above catalyst with 600 mg of silicon carbide, it was placed on a micro fixed-bed reactor, and the catalytic activity was tested at 280 °C to 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 After the reaction reached a steady state, the tail gas after the reaction was analyzed online by SHIMADZU GC-2014 gas chromatography. The Porapak Q column and 5A molecular sieve column were connected to the TCD detector for separating and analyzing CO, CO2, and O2. The alumina capillary column was connected to the FID detector for separating and detecting hydrocarbons. The RTX-1 capillary column was connected to the FID detector for separating and detecting oxygen-containing organic compounds 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.

[0071] Preliminary Example 5

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

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

[0074] After mixing 600 mg of the above first oxide with 600 mg of silicon carbide for dilution, it is placed on a micro fixed-bed reactor, and the catalytic activity is tested at 280 °C to 380 °C. The reaction gas composition is O2-C3H6-H2O-He = 1-3.7-6.3-13, and the reaction gas space velocity is 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 chromatography. The Porapak Q column and 5A molecular sieve column are connected to the TCD detector for the separation and analysis of CO, CO2, and O2. The alumina capillary column is connected to the FID detector for the separation and detection of hydrocarbons. The RTX-1 capillary column is connected to the FID detector for the separation and detection of oxygen-containing organic compounds 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.

[0075] Comparative Example 1

[0076] The catalysts in Preparation Comparative Example 1 and Preparation Comparative Example 2 were mixed according to 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 1.

[0077] The catalytic performance of the prepared Comparative Catalyst 1 was tested:

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

[0079] Comparative Example 2

[0080] The catalysts in Preparation Comparative Example 1 and Preparation Comparative Example 2 were mixed in a mass ratio of 6:4, and then the mixture was placed in a QM-3SP2 planetary ball mill and ground and mixed evenly to obtain Comparative Catalyst 2.

[0081] The catalytic performance of the prepared Comparative Catalyst 2 was tested:

[0082] 600 mg of the above Comparative Catalyst 2 was taken and diluted and mixed with 600 mg of silicon carbide, and then placed on a micro fixed-bed reactor, and the catalytic activity was tested at 280 °C to 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 After the reaction reached a steady state, the tail gas after the reaction was analyzed online by a SHIMADZU GC-2014 gas chromatograph. A Porapak Q column and a 5A molecular sieve column were connected to a TCD detector for the separation and analysis of CO, CO2, and O2. An alumina capillary column was connected to an FID detector for the separation and detection of hydrocarbons. An RTX-1 capillary column was connected to an FID detector for the separation and detection of oxygen-containing organic compounds such as acrylic acid and acetic acid. The specific catalytic activity is shown in Table 3.

[0083] Comparative Example 3

[0084] The catalysts in Preparation Comparative Example 3 and Preparation 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 of the prepared Comparative Catalyst 3 was tested:

[0086] 600 mg of the above Comparative Catalyst 1 was taken and diluted and mixed with 600 mg of silicon carbide, and then placed on a micro fixed-bed reactor, and the catalytic activity was tested at 280 °C to 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 -1After the reaction reached a steady state, the tail gas after the reaction was analyzed online by SHIMADZU GC-2014 gas chromatography. A Porapak Q column and a 5A molecular sieve column were connected to a TCD detector for the separation and analysis of CO, CO2, and O2. An alumina capillary column was connected to an FID detector for the separation and detection of hydrocarbons. An RTX-1 capillary column was connected to an FID detector for the separation and detection of oxygen-containing organic compounds such as acrylic acid and acetic acid. The specific catalytic activity is shown in Table 3.

[0087] Example 1

[0088] The catalysts in Preparation Example 1 and Preparation 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 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 taken and diluted and mixed with 600 mg of silicon carbide, and then placed on a micro fixed-bed reactor, and the catalytic activity was tested at 280 °C to 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 After the reaction reached a steady state, the tail gas after the reaction was analyzed online by SHIMADZU GC-2014 gas chromatography. A Porapak Q column and a 5A molecular sieve column were connected to a TCD detector for the separation and analysis of CO, CO2, and O2. An alumina capillary column was connected to an FID detector for the separation and detection of hydrocarbons. An RTX-1 capillary column was connected to an FID detector for the separation and detection of oxygen-containing organic compounds such as acrylic acid and acetic acid. The specific catalytic activity is shown in Table 3.

[0091] Example 2

[0092] The catalysts in Preparation Example 2 and Preparation 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 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 taken and diluted and mixed with 600 mg of silicon carbide, and then placed on a micro fixed-bed reactor, and the catalytic activity was tested at 280 °C to 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 -1After the reaction reached a steady state, the tail gas after the reaction was analyzed online by SHIMADZU GC-2014 gas chromatography. A Porapak Q column and a 5A molecular sieve column were connected to a TCD detector for the separation and analysis of CO, CO2, and O2. An alumina capillary column was connected to an FID detector for the separation and detection of hydrocarbons. An RTX-1 capillary column was connected to an FID detector for the separation and detection of oxygen-containing organic compounds such as acrylic acid and acetic acid. The specific catalytic activity is shown in Table 3.

[0095] Example 3

[0096] The catalysts in Preparation Example 3 and Preparation 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 a composite oxide catalyst.

[0097] The present invention carried out a catalytic performance test on the prepared composite oxide catalyst:

[0098] 600 mg of the above composite oxide catalyst was taken and diluted and mixed with 600 mg of silicon carbide, and then placed on a micro fixed-bed reactor, and the catalytic activity was tested at 280 °C to 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 After the reaction reached a steady state, the tail gas after the reaction was analyzed online by SHIMADZU GC-2014 gas chromatography. A Porapak Q column and a 5A molecular sieve column were connected to a TCD detector for the separation and analysis of CO, CO2, and O2. An alumina capillary column was connected to an FID detector for the separation and detection of hydrocarbons. An RTX-1 capillary column was connected to an FID detector for the separation and detection of oxygen-containing organic compounds such as acrylic acid and acetic acid. The specific catalytic activity is shown in Table 3.

[0099] Example 4

[0100] The catalysts in Preparation Example 4 and Preparation 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 a composite oxide catalyst.

[0101] A catalytic performance test was carried out on the prepared composite oxide catalyst:

[0102] 600 mg of the above composite oxide catalyst was taken and diluted and mixed with 600 mg of silicon carbide, and then placed on a micro fixed-bed reactor, and the catalytic activity was tested at 280 °C to 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 -1After the reaction reached a steady state, the tail gas after the reaction was analyzed online by SHIMADZU GC-2014 gas chromatography. A Porapak Q column and a 5A molecular sieve column were connected to a TCD detector for the separation and analysis of CO, CO2, and O2. An alumina capillary column was connected to an FID detector for the separation and detection of hydrocarbons. An RTX-1 capillary column was connected to an FID detector for the separation and detection of oxygen-containing organic compounds such as acrylic acid and acetic acid. The specific catalytic activity is shown in Table 3.

[0103] Example 5

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

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

[0106] After 600 mg of the above composite oxide catalyst was diluted and mixed with 600 mg of silicon carbide, it was placed on a micro fixed-bed reactor, and the catalytic activity was tested at 280 °C to 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 After the reaction reached a steady state, the tail gas after the reaction was analyzed online by SHIMADZU GC-2014 gas chromatography. A Porapak Q column and a 5A molecular sieve column were connected to a TCD detector for the separation and analysis of CO, CO2, and O2. An alumina capillary column was connected to an FID detector for the separation and detection of hydrocarbons. An RTX-1 capillary column was connected to an FID detector for the separation and detection of oxygen-containing organic compounds such as acrylic acid and acetic acid. 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 the selective oxidation of high-activity propylene or propane to acrylic acid, comprising the following steps: mixing a molybdenum-vanadium-tellurium-niobium precursor, water and a pore-forming agent uniformly, washing and then 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 and then carrying out a hydrothermal reaction, washing and then drying, roasting and then calcining, and then purifying and calcining for activation to obtain a second oxide; mixing the first oxide and the second oxide to obtain a composite oxide catalyst, namely a catalyst for the selective oxidation of high-activity propylene or propane to acrylic acid. The composite oxide prepared by the above method has a relatively high specific surface area, thereby improving the reaction activity of the selective oxidation of propylene or propane to acrylic acid. Experimental results show that: for the catalyst with the best performance, the propane conversion rate for the selective oxidation of propane to acrylic acid is 75.2%, and the acrylic acid selectivity is 75.6%.

[0114] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a catalyst for the selective oxidation of high-activity propylene or propane to prepare acrylic acid, comprising the following steps: Mix the molybdenum-vanadium-tellurium-niobium precursor, water and pore-forming agent evenly. The raw materials for preparing the molybdenum-vanadium-tellurium-niobium precursor include ammonium molybdate, ammonium niobium oxalate, telluric acid and vanadyl sulfate. After roasting and then calcining, a first oxide is obtained; the pore-forming agent is selected from one or more of ammonium citrate, ammonium acetate and ammonium oxalate; the mass ratio of the pore-forming agent to ammonium molybdate is (1:40) - (1:1); Mix the molybdenum-vanadium-tellurium-niobium precursor and water, carry out hydrothermal reaction, wash and then dry, roast and then calcine, and then purify and calcine for activation to obtain a second oxide; Mix the first oxide and the second oxide to obtain a catalyst for the selective oxidation of high-activity propylene or propane to prepare acrylic acid; The molar ratio of Mo:V:Te:Nb in the molybdenum-vanadium-tellurium-niobium precursor used for preparing the first oxide and the second oxide is 1:(0.2 - 0.4):(0.3 - 0.5):(0.10 - 0.2).

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

3. The preparation method according to claim 1, characterized in that, For preparing the first oxide, the roasting temperature is 200 - 350 °C, and the roasting time is 1 - 6 h; The calcining temperature is 590 - 610 °C, and the calcining time is 110 - 130 min.

4. 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 - 50 h.

5. The preparation method according to claim 1, characterized in that, For preparing the second oxide, the roasting temperature is 240 - 260 °C, and the time is 1 - 6 h; The calcining temperature is 590 - 610 °C, and the time is 110 - 130 min.

6. 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) - (10:0.5).

7. A method for the selective oxidation of propylene or propane to prepare acrylic acid, comprising the following steps: Mix the catalyst for the selective oxidation of high-activity propylene or propane to prepare acrylic acid prepared by the method according to any one of claims 1 - 6 with silicon carbide, and carry out catalytic reaction in a mixed gas of propylene or propane, oxygen, helium and water vapor to obtain acrylic acid.

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