Preparation method of acetic acid removal catalyst in industrial tail gas and application of acetic acid removal catalyst in ethane oxidation dehydrogenation reaction for preparing ethylene

Abstract

The application provides a preparation method of an acetic acid removal catalyst in an industrial tail gas and application of the catalyst in an ethane oxidative dehydrogenation reaction for preparing ethylene, and belongs to the technical field of petroleum chemical industry.The active component of the catalyst is non-noble metal oxides such as Fe, Cu, Ce and Zn and mixed oxides therebetween, which are then physically mixed with pure M1 phase molybdenum vanadium tellurium niobium mixed oxide.The catalyst is prepared by using an impregnation method, then dried in air, and calcined in a muffle furnace at 400 DEG C to 600 DEG C.The catalyst obtained by the application can efficiently remove by-product acetic acid while not changing the selectivity of ethylene in the ethane oxidative dehydrogenation reaction for preparing ethylene.The catalyst can simplify the separation process procedure of the ethane oxidative dehydrogenation reaction for preparing ethylene, reduce the corrosion to equipment, and has a good industrial application prospect.

Description

Technical Field

[0001] This invention relates to the field of petrochemical technology, specifically to a method for preparing an acetic acid removal catalyst from industrial tail gas and its application in the oxidative dehydrogenation of ethane to produce ethylene. Background Technology

[0002] Ethylene (C2H4) is one of the world's largest-produced chemical products and an important basic chemical raw material, mainly used in the synthesis of fibers, rubber, plastics, acrylic fibers, adhesives, and other chemicals. Currently, industrially, ethylene is primarily produced through naphtha steam cracking; however, due to limited crude oil resources, this route's capacity is nearing saturation. Producing ethylene from ethane via thermal cracking significantly reduces costs. However, ethane thermal cracking is an endothermic reaction, and due to thermodynamic equilibrium limitations, reaction temperatures exceeding 900℃ result in high energy consumption. Furthermore, the cracking furnace is prone to carbon buildup and coking, the equipment is complex, and operating costs are high.

[0003] The oxidative dehydrogenation of ethane to ethylene is a novel, low-energy-consumption method for ethylene production, attracting widespread attention from researchers. Among numerous ethane oxidative dehydrogenation catalysts, the molybdenum-vanadium-tellurium-niobium mixed metal oxide catalyst has great potential for industrial application due to its high activity. However, this catalyst inevitably produces a small amount of acetic acid (selectivity less than 5%) during the ethane-to-ethylene process.

[0004] Currently, the conventional method for removing acetic acid is separation. For example, G. Mikidis et al. (CN108349845A) proposed washing the reaction tail gas with water and then extracting the acetic acid from the water; Yan Binghai et al. (CN112142547A) proposed first separating the reaction tail gas into gas and liquid, and then feeding it into an absorption tower to obtain deacidified gas. Because the selectivity and concentration of the byproduct acetic acid in this reaction are very low, separating it would significantly increase energy consumption and cost. Furthermore, the presence of acetic acid places higher demands on the corrosion resistance of the process equipment, increasing investment costs. Therefore, oxidizing and removing the small amount of acetic acid in the tail gas would simplify the separation process for the ethane oxidative dehydrogenation to ethylene reaction, reduce equipment corrosion, and lower production costs.

[0005] Currently, the catalysts for acetic acid oxidation are mainly VOCs catalytic combustion catalysts, with Pt and Pd being the primary noble metal catalysts used in industrial applications. Besides their high cost, these catalysts exhibit high catalytic activity, enabling the co-catalytic combustion of hydrocarbons, making it difficult to selectively remove acetic acid in the ethane oxidative dehydrogenation to ethylene reaction. Therefore, developing high-performance, highly selective acetic acid removal catalysts for the complex chemical industry tail gas systems is of great significance for the industrial application of the ethane oxidative dehydrogenation to ethylene reaction. Summary of the Invention

[0006] To address the problem of acetic acid removal from the tail gas of ethane oxidative dehydrogenation reaction, this invention provides a method for preparing an acetic acid removal catalyst for industrial tail gas and its application. The specific technical solution is as follows:

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] In a first aspect, the present invention provides a method for preparing an acetic acid removal catalyst, which is carried out according to the following steps:

[0009] An Fe-based precursor solution doped with one or more elements is impregnated in an oxide support, and then dried and calcined to obtain an acetic acid oxidation catalyst. The catalyst is then physically ground and mixed with pure M1 phase MoVTeNOx oxide, and calcined to obtain the final catalyst.

[0010] Preferably, the mass fraction of Fe in the acetic acid oxidation catalyst is 0.02-0.2%.

[0011] Preferably, the doping element is one or two of Cu, Ce, Zn, Ca, K, Na, Mg, and Cs.

[0012] Preferably, the molar ratio of the dopant element to the molar ratio of Fe element is 1:5 to 1:20.

[0013] Preferably, the oxide support is one or more of Al2O3, TiO2, and SiO2.

[0014] Preferably, the roasting temperature is 400℃-600℃ and the roasting time is 2h-12h.

[0015] Preferably, the Fe-based precursor solution is a solution prepared by ferric nitrate and nitrate of doped elements.

[0016] In a second aspect, the present invention provides an acetic acid removal catalyst from industrial exhaust gas, comprising an acetic acid oxidation catalyst and an M1 phase MoVTeNOx oxide;

[0017] The acetic acid oxidation catalyst is an Fe-based catalyst with doped elements supported on an oxide support.

[0018] Preferably, the mass ratio of the acetic acid oxidation catalyst to the M1 phase MoVTeNOx oxide is (0-0.5):1.

[0019] In a third aspect, the present invention provides the application of the acetic acid removal catalyst prepared by the method described above or the acetic acid removal catalyst prepared by the method described above in the coupled oxidative removal of acetic acid in the reaction of ethane oxidative dehydrogenation to ethylene.

[0020] The beneficial effects of this invention are as follows:

[0021] The active component of the catalyst of this invention is a mixture of non-noble metal oxides such as Fe, Cu, Ce, and Zn-based oxides, and their mixtures, which are then physically mixed with pure M1-phase molybdenum-vanadium-tellurium-niobium mixed oxides. The catalyst obtained by this invention can efficiently remove the byproduct acetic acid in the oxidative dehydrogenation of ethane to ethylene without altering the ethylene selectivity. This catalyst simplifies the separation process in the oxidative dehydrogenation of ethane to ethylene, reduces equipment corrosion, and has promising prospects for industrial application. Detailed Implementation

[0022] A method for preparing an acetic acid removal catalyst from industrial exhaust gas includes the following steps:

[0023] An Fe-based precursor solution doped with one or more elements is impregnated in an oxide support, and then dried and calcined to obtain an acetic acid oxidation catalyst. The catalyst is then physically ground and mixed with pure M1 phase MoVTeNOx oxide, and calcined to obtain the final catalyst.

[0024] Specifically, the preparation method is as follows:

[0025] 1. Prepare a solution by mixing an appropriate amount of ferric nitrate and the nitrate of the doped element, and then impregnate the solution onto the oxide carrier.

[0026] The mass fraction of Fe is 0.02-0.2.

[0027] The doping element is one or two of the following: Cu, Ce, Zn, Ca, K, Na, Mg, and Cs;

[0028] The molar ratio of the dopant element to the molar ratio of Fe is 1:5-1:20;

[0029] The oxide support is one of Al2O3, TiO2, and SiO2.

[0030] 2. After impregnation, the catalyst is dried at 60-120℃, preferably at 80℃ for 12 hours. The dried catalyst is then ground and calcined at 400℃-600℃ for 2-12 hours, preferably at 500℃-600℃ for 2-6 hours, and more preferably at 550℃ for 4 hours, to obtain the acetic acid oxidation catalyst.

[0031] 3. After physically grinding and mixing the prepared acetic acid oxidation catalyst with pure M1 phase MoVTeNbOx oxide, calcining it at 400-600℃ for 2-8 hours under an inert atmosphere, pressing it into tablets and sieving it to 40-80 mesh to obtain the final catalyst.

[0032] This invention provides a catalyst for the removal of acetic acid from industrial exhaust gas, comprising an acetic acid oxidation catalyst and an M1 phase MoVTeNOx oxide;

[0033] The acetic acid oxidation catalyst is an Fe-based catalyst with doped elements supported on an oxide support.

[0034] In this invention, the mass ratio of the acetic acid oxidation catalyst to the M1 phase MoVTeNOx oxide is preferably (0-0.5):1, more preferably (0.25-0.5):1, and most preferably 0.5:1 or 0.25:1.

[0035] This invention provides a catalyst prepared above for the oxidative removal of acetic acid in the oxidative dehydrogenation of ethane to ethylene. Specifically, the catalyst is diluted and mixed with silicon carbide, and the reaction is carried out in a mixture of ethane, oxygen, argon or water vapor at a reaction temperature of 200℃-400℃ and a total space velocity of 720-3600 L / kg-cat / h in a fixed-bed reactor.

[0036] Preferably, the reaction atmosphere is a mixture of ethane, oxygen, and water vapor (gas ratio of 3:2:5) or a mixture of ethane, oxygen, and argon (gas ratio of 3:2:5), the total gas flow rate is 30 ml / min, and the reaction temperature is 300℃-400℃.

[0037] To further illustrate the present invention, the following detailed description is provided in conjunction with embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0038] The reagents used in the following embodiments of the present invention, such as gases (ethane, oxygen, argon, etc.) and reagents such as ferric nitrate, copper nitrate, calcium nitrate, telluric acid, ammonium niobate oxalate, and ammonium molybdate, were all purchased from the market.

[0039] Comparative Example 1

[0040] According to the molar ratio of Mo:V:Te:Nb = 1:0.25:0.23:0.12, under heating conditions at 80℃, a certain amount of ammonium niobate oxalate was weighed and dissolved in deionized water to obtain solution 1. Similarly, a certain amount of ammonium molybdate, vanadium oxysulfate, and telluric acid were weighed and dissolved in deionized water to obtain solution 2. Solutions 1 and 2 were combined and stirred evenly to obtain the precursor solution, and then stirred evenly again. The evenly mixed solution was transferred to a hydrothermal reactor and heated at 1... Hydrothermal synthesis was performed at 75℃ for 48 hours. The suspension obtained by hydrothermal synthesis was washed by centrifugation and dried overnight at 80℃ in a forced-air drying oven. The precursor was calcined at 600℃ for 2 hours under an argon atmosphere. The calcined catalyst was then placed in a 7.5% hydrogen peroxide solution, heated to 60℃, stirred for 3 hours, washed by centrifugation with deionized water, and dried overnight at 110℃ to obtain pure M1 phase molybdenum-vanadium-tellurium-niobium composite metal oxide (pure M1 phase MoVTeNbOx catalyst).

[0041] The catalytic performance of the prepared Comparative Example 1 catalyst was tested:

[0042] 300 mg of the above catalyst was diluted and mixed with 400 mg of silicon carbide, and then placed in a micro fixed-bed reactor. The reaction atmosphere was a mixture of ethane, oxygen, and argon (gas ratio 3:2:5), the total gas flow rate was 30 ml / min, and the reaction temperature was 300℃-400℃ (selected temperature conditions were 300℃, 325℃, and 350℃). The gas composition after the reaction was detected by online gas chromatography (Shimadzu GC-2014 gas chromatograph, HP-AL2O3 / s column and Rtx-1 column connected to FID detector, PorapakQ column connected to TCD detector, high-purity helium as carrier gas). Specific catalytic activity is shown in Table 1.

[0043] As shown in Table 1, when using the catalyst of Comparative Example 1, the selectivity of acetic acid is significantly improved with the increase of ethane conversion, and the concentration of the byproduct acetic acid also increases significantly.

[0044] Table 1. Catalyst performance test results for Comparative Example 1

[0045]

[0046] Example 1

[0047] 43 mg of ferric nitrate was dissolved in 1 ml of water. The solution was then uniformly impregnated onto 1 g of Al2O3. The catalyst was then dried at 80 °C for 12 h. The dried catalyst was ground and calcined at 550 °C for 4 h to obtain the acetic acid oxidation catalyst. The above catalyst and pure M1 phase MoVTeNOx oxide (Comparative Example 1) catalyst were ground and mixed at a mass ratio of 1:2. The mixture was then calcined at 600 °C for 2 h under a nitrogen atmosphere, pressed into tablets, and sieved to 40-80 mesh to obtain the final catalyst.

[0048] The catalytic performance of the prepared catalyst was tested.

[0049] Take 300 mg of the above catalyst and 400 mg of silicon carbide, mix and dilute them, and place them in a micro fixed-bed reactor. The reaction atmosphere is a mixture of ethane, oxygen, and argon (gas ratio of 3:2:5), the total gas flow rate is 30 ml / min, and the reaction temperature is 300℃-400℃. Refer to Table 2 for specific catalytic activity.

[0050] Table 2 Catalyst performance test results in Example 1

[0051]

[0052] Example 2

[0053] Weigh out 83 mg of ferric nitrate and 8.8 mg of copper nitrate and dissolve them in 1 ml of water. Then, uniformly impregnate 1 g of Al2O3 with the solution. The catalyst is then dried at 80 °C for 12 h. After drying, the catalyst is ground and calcined at 550 °C for 4 h. The above catalyst and pure M1 phase MoVTeNOx oxide (Comparative Example 1) catalyst are ground and mixed at a mass ratio of 1:2. Then, the mixture is calcined at 600 °C for 2 h under a nitrogen atmosphere, pressed into tablets, and sieved to 40-80 mesh to obtain the final catalyst.

[0054] The catalytic performance of the prepared catalyst was tested.

[0055] Take 300 mg of the above catalyst and 400 mg of silicon carbide, mix and dilute them, and place them in a micro fixed-bed reactor. The reaction atmosphere is a mixture of ethane, oxygen, and argon (gas ratio of 3:2:5), the total gas flow rate is 30 ml / min, and the reaction temperature is 300℃-400℃. Refer to Table 3 for specific catalytic activities.

[0056] Table 3. Catalyst performance test results in Example 2

[0057]

[0058] Example 3

[0059] Weigh 43 mg of ferric nitrate and 12 mg of calcium nitrate and dissolve them in 1 ml of water. Then, uniformly impregnate 1 g of Al2O3 with the solution. The catalyst is then dried at 80 °C for 12 h. After drying, the catalyst is ground and calcined at 550 °C for 4 h. The above catalyst and pure M1 phase MoVTeNOx oxide (Comparative Example 1) catalyst are ground and mixed at a mass ratio of 1:2. Then, the mixture is calcined at 400 °C for 4 h under a nitrogen atmosphere, pressed into tablets, and sieved to 40-80 mesh to obtain the final catalyst.

[0060] The catalytic performance of the prepared catalyst was tested.

[0061] Take 300 mg of the above catalyst and 400 mg of silicon carbide, mix and dilute them, and place them in a micro fixed-bed reactor. The reaction atmosphere is a mixture of ethane, oxygen, and argon (gas ratio of 3:2:5), the total gas flow rate is 30 ml / min, and the reaction temperature is 300℃-400℃. Refer to Table 4 for specific catalytic activities.

[0062] Table 4. Catalyst performance test results in Example 3

[0063]

[0064] Example 4

[0065] Weigh out 86 mg of ferric nitrate, 6 mg of zinc nitrate, and 5 mg of potassium nitrate and dissolve them in 1 ml of water. Then, uniformly impregnate 1 g of Al2O3 with the solution. Subsequently, bake the catalyst at 80 °C for 12 h. Grind the dried catalyst and calcine it at 550 °C for 4 h. Grind and mix the above catalyst with pure M1 phase MoVTeNOx oxide (Comparative Example 1) catalyst at a mass ratio of 1:2. Then, calcine it at 600 °C for 2 h under a nitrogen atmosphere, compress it into tablets, and sieve it to 40-80 mesh to obtain the final catalyst.

[0066] The catalytic performance of the prepared catalyst was tested.

[0067] Take 300 mg of the above catalyst and 400 mg of silicon carbide, mix and dilute them, and place them in a micro fixed-bed reactor. The reaction atmosphere is a mixture of ethane, oxygen, and argon (gas ratio of 3:2:5), the total gas flow rate is 30 ml / min, and the reaction temperature is 300℃-400℃. Refer to Table 5 for specific catalytic activities.

[0068] Table 5. Catalyst performance test results in Example 4

[0069]

[0070] As can be seen from the comparison in Tables 1-5, we can clearly observe that its ethane conversion rate, ethylene selectivity and ethylene yield are not significantly different from those of the catalyst in Comparative Example 1, but it can significantly and efficiently remove acetic acid from the reaction tail gas.

[0071] Example 5

[0072] Weigh out 300 mg of the catalyst and 400 mg of silicon carbide from Example 4, mix and dilute them, and place them in a micro fixed-bed reactor. The reaction atmosphere is a mixture of ethane, oxygen, and water vapor (gas ratio of 3:2:5), the total gas flow rate is 30 ml / min, and the reaction temperature is 300℃-400℃. Specific catalytic activities are shown in Table 6.

[0073] Table 6. Catalyst performance test results in Example 5

[0074]

[0075] As can be seen from the comparison in Table 6, after replacing the argon gas in the reaction equilibrium gas with water vapor, the catalyst can still maintain a good acetic acid removal efficiency and has good adaptability.

[0076] Example 6

[0077] The acetic acid oxidation catalyst prepared according to the above method and the pure M1 phase MoVTeNOx oxide (Comparative Example 1) catalyst were ground and mixed at a mass ratio of 1:4. Then, the mixture was calcined at 600 degrees Celsius for 2 hours under a nitrogen atmosphere, pressed into tablets, and sieved to 40-80 mesh to obtain the final catalyst.

[0078] The catalytic performance of the prepared catalyst was tested.

[0079] 300 mg of the above catalyst was diluted and mixed with 400 mg of silicon carbide, and then placed in a micro fixed-bed reactor. The reaction atmosphere was a mixture of ethane, oxygen, and water vapor (gas ratio of 3:2:5), the total gas flow rate was 30 ml / min, and the reaction temperature was 300℃-400℃. Specific catalytic activity is shown in Table 7.

[0080] Table 7. Catalyst performance test results in Example 6

[0081]

[0082] As can be seen from the above examples and comparative examples, the acetic acid removal catalyst prepared by the present invention can efficiently remove acetic acid present in the tail gas while maintaining stable ethane conversion, ethylene selectivity and ethylene yield.

[0083] The technical solution of the present invention has been described in conjunction with the preferred embodiments of the examples. Those skilled in the art will readily understand that the above description is only a part of the embodiments of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. The application of a catalyst for the removal of acetic acid from industrial tail gas, characterized in that, The catalyst is used for the coupled oxidative removal of acetic acid in the oxidative dehydrogenation of ethane to ethylene, and the preparation method of the catalyst includes the following steps: The Fe-based precursor solution doped with two elements was impregnated in an oxide support, and then dried and calcined to obtain an acetic acid oxidation catalyst. The catalyst was then physically ground and mixed with pure M1 phase MoVTeNbOx oxide, and calcined to obtain the final catalyst. The mass fraction of Fe in the acetic acid oxidation catalyst is 0.02-0.2%. The doping elements are: Zn and K; The molar ratio of the dopant element to the Fe element is 1:5-1:20; The oxide support is Al2O3; The Fe-based precursor solution is a solution prepared by ferric nitrate and nitrate of doped elements; The acetic acid removal catalyst in the industrial exhaust gas includes an acetic acid oxidation catalyst and an M1 phase MoVTeNbOx oxide; the acetic acid oxidation catalyst is an Fe-based catalyst with doped elements supported on an oxide support; the mass ratio of the acetic acid oxidation catalyst to the M1 phase MoVTeNbOx oxide is (0-0.5):1, and the mass ratio is not 0.

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