Preparation method of reaction catalyst for preparing acrylic acid through selective oxidation of propane

Abstract

The invention relates to the technical field of catalysts, in particular to a preparation method of a reaction catalyst for preparing acrylic acid through selective oxidation of propane, which comprises the following steps: adding a precursor salt solution into an aqueous solution, uniformly stirring, adding a certain mass of an active agent into the solution, uniformly stirring, and drying to obtain the catalyst. The preparation method comprises the following steps: preparing a solution, carrying out hydrothermal treatment on the solution at a certain temperature, washing and drying, roasting the obtained solid in a muffle furnace, and finally roasting the roasted solid in a tubular furnace under the protection of argon to obtain the final catalyst. According to the present invention, the preparation method has the simple process, and comprises the two steps of acrylic acid reaction catalyst preparation and acrylic acid preparation through the catalytic reaction of the catalyst, such that the propane conversion rate and the acrylic acid selectivity are significantly improved compared with the acrylic acid reaction catalyst prepared by the traditional method, meanwhile, the whole method is convenient to operate and easy to repeat, and has a good application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of catalysts, and in particular to a method for preparing a catalyst for preparing acrylic acid through selective oxidation of 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 as raw material.

[0003] MoVTeNbOx mixed oxide is also a relatively excellent catalytic system for the selective oxidation of propylene to propylene 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] The purpose of the present invention is to propose a method for preparing a catalyst for the selective oxidation of propane to prepare acrylic acid in order to significantly adjust the phase composition of the catalyst and thereby improve the reaction activity of the selective oxidation of propane to prepare acrylic acid.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A method for preparing a catalyst for preparing acrylic acid by selective oxidation of propane comprises the following steps: The precursor salt solution is placed in an aqueous solution and stirred evenly, then a certain mass of an active agent is placed in the solution and stirred evenly, then the solution is hydrothermally heated at a certain temperature, then washed and dried, and the obtained solid is placed in a muffle furnace for roasting, and finally the roasted solid is placed in a tubular furnace for calcination under argon protection to obtain the final catalyst; the above catalyst is diluted and mixed with silicon carbide, and catalytically reacted in a mixed gas of propane, oxygen, helium and water vapor to obtain acrylic acid.

[0006] As a further description of the above technical solution: The precursor salts are ammonium molybdate, ammonium niobium oxalate, telluric acid and vanadyl sulfate.

[0007] As a further description of the above technical solution: The molar ratio of each element in the precursor salt is: Mo:V:Te:Nb=1:0.2-0.4:0.2-0.5:0.10-0.2.

[0008] As a further description of the above technical solution: The hydrothermal temperature of the solution was 175° C. and the stirring time was 48 h.

[0009] As a further description of the above technical solution: The active agent is one or more of ammonium citrate, citric acid, and sodium citrate.

[0010] As a further description of the above technical solution: The mass ratio of the active agent to ammonium molybdate is 1:40-1:3.

[0011] As a further description of the above technical solution: The calcination temperature of the muffle furnace is 250° C., and the calcination time is 2 hours.

[0012] As a further description of the above technical solution: The calcination temperature is 600° C. and the calcination time is 2 h.

[0013] As a further description of the above technical solution: The content of water vapor is preferably 30%-85%.

[0014] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: In the present invention, the preparation method has a simple process and is divided into two steps, namely, preparing an acrylic acid reaction catalyst and preparing acrylic acid by using the catalyst to participate in a catalytic reaction. Compared with the acrylic acid reaction catalyst prepared in a traditional manner, the propane conversion rate and acrylic acid selectivity thereof are significantly improved, and the efficiency of preparing acrylic acid by selective oxidation of propane is effectively improved. At the same time, the whole method is easy to operate, easy to repeat, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The present invention discloses an XRD spectrum of a catalyst in a method for preparing a catalyst for a reaction of preparing acrylic acid by selective oxidation of propane. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] The reagents used in the following comparative examples and embodiments of the present invention, such as gases (propylene, oxygen, argon, helium, etc.) and vanadyl sulfate, telluric acid, ammonium niobium oxalate, ammonium molybdate, ammonium citrate, citric acid, sodium citrate, etc., were purchased from the market. See also Figure 1 The present invention provides a technical solution: a method for preparing a catalyst for preparing acrylic acid by selective oxidation of propane, comprising the following steps: According to the molar ratio of Mo:V:Te:Nb=1:0.2-0.4:0.2-0.5:0.10-0.2, ammonium molybdate, ammonium niobium oxalate, telluric acid and vanadyl sulfate solution are placed in an aqueous solution and stirred evenly, then a certain mass of an activator is placed in the solution and stirred evenly, the activator is one or more of ammonium citrate, citric acid, sodium citrate, and the mass ratio of the activator to ammonium molybdate is controlled to be 1:40-1:3, then the solution is hydrothermally heated at 175°C, the stirring time is 48h, then washed and dried, and the obtained solid is placed in a muffle furnace for calcination at a calcination temperature of 250°C and a calcination time of 2h, and finally the calcined solid is placed in a tubular furnace under argon protection for calcination at a calcination temperature of 600°C and a calcination time of 2h to obtain the final catalyst; The catalyst is diluted and mixed with silicon carbide, and catalytically reacted in a mixed gas of propane, oxygen, helium and water vapor to obtain acrylic acid, wherein the content of water vapor is controlled to be 10%-85%.

[0018] Comparative Example 1 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 was weighed 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 were weighed and dissolved in 50ml of deionized water to obtain solution 2. Solution 1 and solution 2 were mixed and then hydroheated at 175°C for 48h. The hydrothermal catalyst was then washed and dried, and the obtained precursor was placed in a muffle furnace and calcined at 250°C for 2h, and then calcined at 600°C for 2h in an argon atmosphere to obtain the final catalyst. The XRD spectrum of the catalyst is shown in FIG. Figure 1 shown.

[0019] The catalytic performance of the prepared catalyst was tested: 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 340°C-380°C.

[0020] The reaction gas composition is O2-C3H8-H2O-He=10%-5%-40%-45%, and the reaction gas space velocity is 3000 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, O, aluminum oxide capillary column is connected to FID detector for separation and detection of hydrocarbons, 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 the following table: Temperature (℃) Propane conversion rate (%) Acrylic acid selectivity (%) 340 6.1 52.5 360 10.2 57 380 18.0 60.5 Example 1 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 was weighed 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 were weighed and dissolved in 50ml of deionized water to obtain solution 2. Solution 1 and solution 2 were mixed and stirred evenly, and then 0.29g of sodium citrate was added, followed by hydroheating at 175°C for 48h, and then the hydrothermal catalyst was washed and dried, and the obtained precursor was placed in a muffle furnace and calcined at 250°C for 2h, and then calcined at 600°C for 2h in an argon atmosphere to obtain the final catalyst. The XRD spectrum of the catalyst is shown in FIG. Figure 1 shown.

[0021] The catalytic performance of the prepared catalyst was tested: 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 340°C-380°C.

[0022] The reaction gas composition is O2-C3H8-H2O-He=10%-5%-40%-45%, and the reaction gas space velocity is 3000 mL∙h -1 ∙g -1When 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, O, aluminum oxide capillary column is connected to FID detector for separation and detection of hydrocarbons, 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 the following table: Temperature (℃) Propane conversion rate (%) Acrylic acid selectivity (%) 340 8.0 57.0 360 12.6 63.5 380 22.1 64.5 Example 2 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 was weighed 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 were weighed and dissolved in 50ml of deionized water to obtain solution 2. Solution 1 and solution 2 were mixed and stirred evenly, and then 0.22g of citric acid was added, followed by hydroheating at 175°C for 48h, and then the hydrothermal catalyst was washed and dried, and the obtained precursor was placed in a muffle furnace and calcined at 250°C for 2h, and then calcined at 600°C for 2h in an argon atmosphere to obtain the final catalyst. The XRD spectrum of the catalyst is shown in FIG. Figure 1 shown.

[0023] The catalytic performance of the prepared catalyst was tested: 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 340°C-380°C.

[0024] The reaction gas composition is O2-C3H8-H2O-He=10%-5%-40%-45%, and the reaction gas space velocity is 3000 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, O, aluminum oxide capillary column is connected to FID detector for separation and detection of hydrocarbons, 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 the following table: Temperature (℃) Propane conversion rate (%) Acrylic acid selectivity (%) 340 15.5 68.8 360 28.9 72.9 380 45.6 73.1 Example 3 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 was weighed 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 were weighed and dissolved in 50ml of deionized water to obtain solution 2. Solution 1 and solution 2 were mixed and stirred evenly, and then 0.44g of citric acid was added, followed by hydroheating at 175°C for 48h, and then the hydrothermal catalyst was washed and dried, and the obtained precursor was placed in a muffle furnace and calcined at 250°C for 2h, and then calcined at 600°C for 2h in an argon atmosphere to obtain the final catalyst. The XRD spectrum of the catalyst is shown in FIG. Figure 1 shown.

[0025] The catalytic performance of the prepared catalyst was tested: 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 340°C-380°C.

[0026] The reaction gas composition is O2-C3H8-H2O-He=10%-5%-40%-45%, and the reaction gas space velocity is 3000 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, O, aluminum oxide capillary column is connected to FID detector for separation and detection of hydrocarbons, 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 the following table: Temperature (℃) Propane conversion rate (%) Acrylic acid selectivity (%) 340 13 62.1 360 21.9 67.1 380 35.7 65.5 Example 4 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 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 stirred evenly, and then 0.22g of citric acid and 0.29g of sodium citrate are added and stirred evenly, and then hydroheated at 175°C for 48h, and then the hydroheated catalyst is 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 to obtain the final catalyst. The XRD spectrum of the catalyst is shown in FIG. Figure 1 shown.

[0027] The catalytic performance of the prepared catalyst was tested: 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 340°C-380°C.

[0028] The reaction gas composition is O2-C3H8-H2O-He=10%-5%-40%-45%, and the reaction gas space velocity is 3000 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, O, aluminum oxide capillary column is connected to FID detector for separation and detection of hydrocarbons, 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 the following table: Temperature (℃) Propane conversion rate (%) Acrylic acid selectivity (%) 340 11.8 63.5 360 18.9 66.8 380 30.9 68.2 Example 5 600 mg of the catalyst in Example 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 340°C-380°C.

[0029] The reaction gas composition is O2-C3H8-H2O-He=10%-5%-70%-15%, and the reaction gas space velocity is 3000 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, O, aluminum oxide capillary column is connected to FID detector for separation and detection of hydrocarbons, 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 the following table: Temperature (℃) Propylene conversion rate (%) Acrylic acid selectivity (%) 340 21.5 73.2 360 34.2 73.6 380 48.9 75.2 In summary, through the above-mentioned set of comparative examples and five sets of embodiment tables and Figure 1 Analysis of the XRD spectrum of the catalyst shows that: First, in Comparative Example 1, the average propane conversion rate and acrylic acid selectivity in the temperature range of 340°C are 6.1% and 52.5%, respectively; the average propane conversion rate and acrylic acid selectivity in the five groups of examples at 340°C are 13.96% and 64.92%, respectively; the average propane conversion rate and acrylic acid selectivity in the temperature range of 360°C in Comparative Example 1 are 10.2% and 57%, respectively; the average propane conversion rate and acrylic acid selectivity in the five groups of examples at 360°C are 23.3% and 68.78%, respectively; the average propane conversion rate and acrylic acid selectivity in the temperature range of 380°C in Comparative Example 1 are 18.0% and 60.5%, respectively; the average propane conversion rate and acrylic acid selectivity in the five groups of examples at 380°C are 36.64% and 69.3%, respectively. Therefore, the propane conversion rate and acrylic acid selectivity of the acrylic acid reaction catalyst prepared by the preparation method are higher than those of the acrylic acid reaction catalyst obtained by conventional technical means in the comparative example.

[0030] Second, Example 5 is an extended example of Example 2. In Example 2, the proportions of oxygen, propane, water vapor and helium in the reaction gas group are 10%, 5%, 40% and 45%, respectively. In Example 5, the proportions of oxygen, propane, water vapor and helium in the reaction gas group are 10%, 5%, 70% and 15%, respectively. By increasing the proportion of water vapor in the reaction gas group, the propane conversion rate and acrylic acid selectivity in the temperature range of 340°C are increased by 6% and 4.4%, respectively, in the temperature range of 360°C, the propane conversion rate and acrylic acid selectivity are increased by 5.3% and 0.7%, respectively, in the temperature range of 380°C, the propane conversion rate and acrylic acid selectivity are increased by 3.3% and 2.1%, respectively. It can be seen that the propane conversion rate and acrylic acid selectivity can be slightly improved by increasing the proportion of water vapor in the reaction gas group.

[0031] Finally, for the acrylic acid reaction catalyst prepared by this preparation method, when the proportion of water vapor in the reaction gas group is 30%-85%, the propane conversion rate and acrylic acid selectivity can be higher than the conventional level. At the same time, this preparation method is simple in process, easy to operate, easy to repeat, and has good application prospects.

[0032] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a catalyst for preparing acrylic acid by selective oxidation of propane, characterized in that: The following steps are involved: The precursor salt solution is placed in an aqueous solution and stirred evenly, then a certain mass of the active agent is placed in the solution and stirred evenly, then the solution is hydrothermally heated at a certain temperature, then washed and dried, and the obtained solid is placed in a muffle furnace for calcination, and finally the calcined solid is placed in a tubular furnace under argon protection to calcine to obtain the final catalyst; The above catalyst is diluted and mixed with silicon carbide, and catalytically reacted in a mixed gas of propane, oxygen, helium and water vapor to obtain acrylic acid.

2. The method for preparing a catalyst for preparing acrylic acid by selective oxidation of propane according to claim 1, characterized in that: The precursor salts are ammonium molybdate, ammonium niobium oxalate, telluric acid and vanadyl sulfate.

3. The method for preparing a catalyst for preparing acrylic acid by selective oxidation of propane according to claim 2, characterized in that: The molar ratio of each element in the precursor salt is: Mo:V:Te:Nb=1:0.2-0.4:0.2-0.5:0.10-0.

2.

4. The method for preparing a catalyst for preparing acrylic acid by selective oxidation of propane according to claim 1, characterized in that: The hydrothermal temperature of the solution was 175° C. and the stirring time was 48 h.

5. The method for preparing a catalyst for preparing acrylic acid by selective oxidation of propane according to claim 1, characterized in that: The active agent is one or more of ammonium citrate, citric acid, and sodium citrate.

6. The method for preparing a catalyst for preparing acrylic acid by selective oxidation of propane according to claim 1, characterized in that: The mass ratio of the active agent to ammonium molybdate is 1:40-1:

3.

7. The method for preparing a catalyst for preparing acrylic acid by selective oxidation of propane according to claim 1, characterized in that: The calcination temperature of the muffle furnace is 250° C., and the calcination time is 2 hours.

8. The method for preparing a catalyst for preparing acrylic acid by selective oxidation of propane according to claim 1, characterized in that: The calcination temperature is 600° C. and the calcination time is 2 h.

9. The method for preparing a catalyst for preparing acrylic acid by selective oxidation of propane according to claim 1, characterized in that: The content of the water vapor is controlled to be 10%-85%.

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