High-yield zeolite-like vanadium molybdate catalyst as well as synthesis method and application thereof

Abstract

The invention discloses a high-yield zeolite vanadium molybdate catalyst, the molecular formula of the catalyst is MoaVfTebOcMd, M is one of transition metal elements Cr, Mn, Fe, Co, Ni and Cu, a, b, c, d and f are molar ratios, a is equal to 2-3, b is equal to 0-0.2, c is equal to 10-20, d is equal to 0.2-0.5, f is equal to 1, the catalyst takes a Mo-V-O composite framework material as a main active component, and M is taken as a co-catalytic component. The catalyst disclosed by the invention does not use noble metal Nb, does not need an oxygen-containing ligand except a complexing agent during preparation, is low in synthesis cost and high in yield, and not only reduces the reaction temperature, but also improves the catalytic performance in the aspect of preparing ethylene by oxidative dehydrogenation of ethane when being used for catalyzing the reaction of preparing ethylene by oxidative dehydrogenation of ethane. The synthesis method of the catalyst is simple in process steps and high in yield, the prepared catalyst is good in catalytic activity, and the yield of ethylene in the ethylene preparation reaction through ethane dehydrogenation can be increased. The yield of the synthesis method of the catalyst can reach more than 80%.

Description

Technical Field

[0001] The present invention belongs to the technical field of inorganic synthesis and catalyst preparation, and particularly relates to a high-yield zeolite-like vanadate molybdate catalyst, a synthesis method thereof, and an application thereof. Background Art

[0002] The oxidative dehydrogenation (ODHE) of ethane over M1-type MoVOTeNb mixed metal oxide is one of the most promising methods for the targeted conversion of ethane in widely existing but relatively dispersed shale gas resources. Oxygen (O2), as the most commonly used oxidant in ODHE, can effectively promote the oxidative dehydrogenation reaction of ethane and accelerate the formation of ethylene under relatively mild conditions due to its wide source and low cost. Generally speaking, the ODHE reaction with O2 as the oxidant is considered to have the greatest potential because it improves the reaction efficiency, reduces the energy consumption, and has the advantages of industrial application. However, problems such as optimizing the reaction conditions, improving the selectivity and conversion rate, and catalyst deactivation still need to be solved.

[0003] The MoVONbTe catalyst (M1 phase) exhibits high ethane conversion (>50%) and high ethylene selectivity (>80%) under mild conditions of 300-450 °C. Its unique crystal structure (such as the seven-membered ring channel) and surface oxygen species (such as lattice oxygen O-) can preferentially promote the dehydrogenation of ethane to ethylene while inhibiting over-oxidation to form CO2. The synergistic effect of its multi-metal components: Mo and V: Mo provides structural stability, and V acts as the main active site to promote ethane activation; Te and Nb: Te regulates the reactivity of surface oxygen species, and Nb enhances the redox ability of the catalyst. The MoVONbTe catalyst achieves efficient oxygen transfer through the dynamic balance of oxygen vacancies and lattice oxygen, maintaining the catalytic cycle. Therefore, the MoVONbTe catalyst has shown excellent performance in laboratory and pilot-scale studies and is considered one of the most promising ODHE catalysts for industrialization. However, the MoVONbTe catalyst still faces many challenges in practical applications: 1) High preparation difficulty: The synthesis of the M1 phase structure requires precise control of the component ratio and heat treatment conditions, and the preparation process is complex and has poor reproducibility (Y. Chen et al., J. Catal. 416 (2022) 277-288); 2) High cost: Elements such as Te and the noble metal Nb are relatively expensive (A.C. Sanfiz et al., Top. Catal. 50 (2008) 19-32), and oxygen-containing ligands need to be added (Daniel Melzer et al., Nat Commun 10, 4012 (2019)), and the yield of the catalyst is relatively low (M. Sadakane et al., Angew. Chem. Int. Ed. 2009, 48, 3782-3786), increasing the cost of the catalyst; 3) Harsh catalytic reaction conditions: The reaction temperature is usually 350-400 °C (A. de Arriba et al., Catal. Today, 418, 114122 (2023)), and the catalyst is prone to carbon deposition, sintering, and phase transformation during high-temperature or long-term reactions, resulting in a decrease in activity. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a high-yield zeolite-like vanadomolybdate catalyst, its synthesis method and application in view of the deficiencies of the prior art. The catalyst of the present invention does not use the noble metal Nb and does not require oxygen-containing ligands except for complexing agents during preparation. It has low synthesis cost and high yield. When used in the catalytic reaction of oxidative dehydrogenation of ethane to ethylene with oxygen, it not only reduces the reaction temperature but also improves the catalytic performance in the oxidative dehydrogenation of ethane to ethylene.

[0005] The technical solution adopted by the present invention to solve the above technical problems is as follows: A high-yield zeolite-like vanadomolybdate catalyst, the molecular formula of the catalyst is Mo a V f Te b Oc M d , where M is one of the transition metal elements Cr, Mn, Fe, Co, Ni, Cu, and a, b, c, d, f are all molar ratios, a = 2 - 3, b = 0 - 0.2, c = 10 - 20, d = 0.2 - 0.5, f = 1. The catalyst uses the Mo-V-O composite framework material as the main active component and M as the co-catalytic component.

[0006] The zeolite-like vanadate molybdate catalyst of the present invention is a highly crystalline and high-yield catalyst containing a mixed metal oxide of molybdenum, vanadium, and tellurium doped with a transition metal element. The present invention does not use the noble metal Nb. By doping inexpensive transition metal elements, while significantly reducing the synthesis cost of the catalyst, the yield of the catalyst is increased, and the catalytic performance of the catalyst is further improved, making the catalyst exhibit extremely high catalytic activity for the oxidative dehydrogenation of ethane to ethylene with oxygen.

[0007] When the catalyst of the present invention is used for the catalytic oxidative dehydrogenation of ethane to ethylene reaction, it not only reduces the reaction temperature but also improves the catalytic performance in the oxidative dehydrogenation of ethane to ethylene.

[0008] Preferably, M is one of trivalent Cr, divalent Mn, divalent Fe, divalent Co, divalent Ni, and divalent Cu.

[0009] The synthesis method of the above high-yield zeolite-like vanadate molybdate catalyst includes the following steps:

[0010] a) Prepare starting compounds containing molybdenum, vanadium, and tellurium, and add a metal salt of M and a complexing agent to the starting compounds to obtain a mixture, where the complexing agent is used to regulate the solution ion concentration, and the molar ratio of the complexing agent to the metal salt of M is 1:(1 - 2);

[0011] b) Hydrothermally treat the mixture obtained in step a) at a temperature of 150 - 200 °C for 24 - 48 hours to obtain an aqueous suspension containing the compound of Mo a V f Te b O c M d ;

[0012] c) Separate and obtain the solid in the aqueous suspension obtained in step b), and dry it at a temperature of 60 - 150 °C (particularly preferably 60 - 80 °C). The obtained solid product is the catalyst Mo a V f Te b O c M d .

[0013] The synthesis method of the catalyst of the present invention uses insoluble and cheap starting compounds containing molybdenum, vanadium and tellurium as raw materials to synthesize a high-crystallization and high-yield catalyst doped with a mixed metal oxide and a transition metal element, and adds a complexing agent to control the ion concentration of the solution. During the preparation, no oxygen-containing ligand is required except for the complexing agent, which further reduces the synthesis cost of the catalyst and greatly improves the yield of the catalyst. In addition, the synthesis method of the present invention uses a synthesis temperature of 150 to 200°C, omits the high-temperature step, reduces energy consumption and simplifies the process. The yield of the synthesis method of the catalyst of the present invention can reach more than 80%.

[0014] Preferably, in step a), the metal salt of M is one of chromium sulfate, manganese sulfate, iron sulfate, cobalt sulfate, nickel sulfate and copper sulfate.

[0015] Preferably, in step a), the starting compound comprises a molybdenum-containing compound, a vanadium-containing compound and a tellurium-containing compound, the molybdenum-containing compound is ammonium heptamolybdate or molybdenum trioxide, the vanadium-containing compound is vanadyl sulfate or vanadium pentoxide, and the tellurium-containing compound is tellurium dioxide.

[0016] Preferably, in step a), the complexing agent is oxalic acid and citric acid, wherein the molar ratio of oxalic acid to citric acid is (1-5):1.

[0017] The application of the high-yield zeolite vanadium molybdate catalyst in the catalytic oxygen oxidation ethane dehydrogenation to ethylene reaction is specifically as follows: the high-yield zeolite vanadium molybdate catalyst is pelletized and then catalyzed in the oxygen oxidation ethane dehydrogenation to ethylene reaction in a fixed bed reactor under normal pressure.

[0018] Preferably, the particle size of the high-yield zeolite vanadium molybdate catalyst after granulation is 20-60 mesh, and the reaction temperature of the catalytic oxygen oxidation ethane dehydrogenation to ethylene reaction is 250-330°C.

[0019] Preferably, in the catalytic oxygen oxidation ethane dehydrogenation to ethylene reaction, the high-yield zeolite vanadium molybdate catalyst is used in an amount of 0.1 to 0.5 g, the total flow rate of the reaction feed gas is 30 to 80 mL / min, the molar percentages of ethane and oxygen in the reaction feed gas are both 10%, and the rest is nitrogen.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] (1) The present invention does not use noble metal Nb. By doping inexpensive transition metal elements, while significantly reducing the synthesis cost of the catalyst, it improves the yield of the catalyst and further enhances the catalytic performance of the catalyst, enabling the catalyst to exhibit extremely high catalytic activity for the oxidative dehydrogenation of ethane to ethylene with oxygen. When the catalyst of the present invention is used in the reaction of oxidative dehydrogenation of ethane to ethylene with oxygen, it not only reduces the reaction temperature but also improves the catalytic performance in the oxidative dehydrogenation of ethane to ethylene.

[0022] (2) The synthesis method of the catalyst of the present invention uses inexpensive insoluble starting compounds containing molybdenum, vanadium, and tellurium as raw materials to synthesize a highly crystalline and high-yield catalyst of mixed metal oxides doped with transition metal elements, and adds a complexing agent to regulate the solution ion concentration. Except for the complexing agent, no oxygen-containing ligand is required during preparation, further reducing the synthesis cost of the catalyst. At the same time, the synthesis method of the catalyst of the present invention has simple process steps and high yield, and the prepared catalyst has good catalytic activity, which can improve the yield of ethylene in the ethane dehydrogenation to ethylene reaction. The yield of the synthesis method of the catalyst of the present invention can reach more than 80%. Taking the catalyst Mo 2.3 V1Te 0.2 O 14 Ni 0.47 as an example, the yield of preparing this catalyst is 80 - 85%. When this catalyst is used in the reaction of oxidative dehydrogenation of ethane to ethylene with oxygen, at a reaction temperature of 300 °C, the highest ethane conversion rate reaches 70 - 75%, and the highest ethylene yield reaches 50 - 55%. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 are the XRD powder diffraction patterns and yield diagrams of the catalysts of Examples 1 - 6;

[0024] Figure 2 are the XRD powder diffraction patterns and yield diagrams of the catalysts of Example 7, Comparative Example 1, and Comparative Example 2;

[0025] Figure 3 are the XRD powder diffraction patterns of the catalysts of Example 7 and Comparative Example 4;

[0026] Figure 4 are the CO2 adsorption - desorption isotherms of the catalysts of Example 7 and Comparative Example 3;

[0027] Figure 5 are the CO2 adsorption - desorption isotherms of the catalysts of Example 7, Comparative Example 1, and Comparative Example 2;

[0028] Figure 6 are the conversion rate diagrams of C2H6 and selectivity diagrams of C2H4 of Application Example 7 - 3 and the catalyst of Application Example 10;

[0029] Figure 7XPS spectra of Mo (3d) signals of Example 7 and Comparative Example 3;

[0030] Figure 8 XPS spectra of V(2p) signals of Example 7 and Comparative Example 3;

[0031] Figure 9 It is the XPS spectra of O(1s) signals of Example 7 and Comparative Example 3;

[0032] Figure 10 It is the XPS spectra of Te (3d) signals of Example 7 and Comparative Example 3;

[0033] Figure 11 XPS spectra of Ni(2p) signals of Example 7 and Comparative Example 3. DETAILED DESCRIPTION

[0034] The present invention is further described in detail below in conjunction with the accompanying drawings, examples, comparative examples and application examples. The raw materials used in the following examples are all commercially available products.

[0035] Example 1: High yield zeolite vanadium molybdate catalyst, molecular formula Mo 2.3 V1Te 0.02 O 14 Cr 0.31 , wherein Cr is trivalent. The synthesis method of the catalyst comprises the following steps: a) mixing 1.25g of MoO3, 0.3415g of V2O5, 0.01g of TeO2 and 0.4637g of Cr2(SO4)3·xH2O in 25.00mL of water, and adding 0.2835g of oxalic acid and 0.1969g of citric acid as complexing agents to obtain a primary mixture, adding the primary mixture to an autoclave with a polytetrafluoroethylene liner, stirring thoroughly, transferring the primary mixture to a reactor and continuing stirring until the mixture is uniformly mixed to obtain a mixture; b) transferring the obtained mixture to a reactor with a polytetrafluoroethylene liner, hydrothermally treating the mixture at a temperature of 190oC for 24 hours, and then slowly cooling the mixture to room temperature to obtain a catalyst containing Mo. 2.3 V1Te 0.02 O 14 Cr 0.31 c) extracting and filtering the solid in the aqueous suspension, and drying it in an oven at 60°C for 12h to obtain a solid product, which is the catalyst Mo 2.3 V1Te 0.02 O 14 Cr 0.31 .

[0036] Example 2: High yield zeolite vanadium molybdate catalyst, molecular formula Mo 2.3 V1Te 0.02 O14 Mn 0.31 , where Mn is divalent. The synthesis method of this catalyst includes the following steps: a) Mix 1.25 g of MoO3, 0.3415 g of V2O5, 0.01 g of TeO2, and 0.1998 g of MnSO4·H2O in 25.00 mL of water, and add 0.2835 g of oxalic acid and 0.1969 g of citric acid as complexing agents to obtain a preliminary mixture. Add this preliminary mixture to an autoclave with a polytetrafluoroethylene lining. After sufficient stirring, transfer it to a reactor and continue stirring until it is evenly mixed to obtain a mixture; b) Transfer the obtained mixture to a reactor with a polytetrafluoroethylene lining, hydrothermally treat it at a temperature of 190 °C for 24 hours, and then slowly cool it to room temperature at room temperature to obtain an aqueous suspension containing Mo 2.3 V1Te 0.02 O 14 Mn 0.31 compound; c) Extract and filter to obtain the solid in the aqueous suspension, and dry it in an oven at 60 °C for 12 h. The obtained solid product is the catalyst Mo 2.3 V1Te 0.02 O 14 Mn 0.31 .

[0037] Example 3: A high-yield zeolite-like vanadium molybdate catalyst with the molecular formula Mo 2.3 V1Te 0.02 O 14 Fe 0.31 , where Fe is divalent. The synthesis method of this catalyst includes the following steps: a) Mix 1.25 g of MoO3, 0.3415 g of V2O5, 0.01 g of TeO2, and 0.3287 g of FeSO4·7H2O in 25.00 mL of water, and add 0.2835 g of oxalic acid and 0.1969 g of citric acid as complexing agents to obtain a preliminary mixture. Add this preliminary mixture to an autoclave with a polytetrafluoroethylene lining. After sufficient stirring, transfer it to a reactor and continue stirring until it is evenly mixed to obtain a mixture; b) Transfer the obtained mixture to a reactor with a polytetrafluoroethylene lining, hydrothermally treat it at a temperature of 190 °C for 24 hours, and then slowly cool it to room temperature at room temperature to obtain an aqueous suspension containing Mo 2.3 V1Te 0.02 O 14 Fe 0.31 compound; c) Extract and filter to obtain the solid in the aqueous suspension, and dry it in an oven at 60 °C for 12 h. The obtained solid product is the catalyst Mo 2.3 V1Te 0.02 O 14 Fe 0.31 .

[0038] Example 4: A high-yield zeolite-like vanadium molybdate catalyst with the molecular formula Mo 2.3 V1Te 0.02 O 14 Co 0.31 , where Co is divalent. The synthesis method of this catalyst includes the following steps: a) Mix 1.25 g of MoO3, 0.3415 g of V2O5, 0.01 g of TeO2, and 0.2945 g of CoSO4·7H2O in 25.00 mL of water, and add 0.2835 g of oxalic acid and 0.1969 g of citric acid as complexing agents to obtain a preliminary mixture. Add this preliminary mixture to an autoclave with a polytetrafluoroethylene lining, stir well, transfer it to a reactor, and continue stirring until it is evenly mixed to obtain a mixture; b) Transfer the obtained mixture to a reactor with a polytetrafluoroethylene lining, hydrothermally treat it at a temperature of 190 °C for 24 hours, and then slowly cool it to room temperature at room temperature to obtain an aqueous suspension containing the Mo 2.3 V1Te 0.02 O 14 Co 0.31 compound; c) Extract and filter to obtain the solid in the aqueous suspension, dry it in an oven at 60 °C for 12 h, and the obtained solid product is the catalyst Mo 2.3 V1Te 0.02 O 14 Co 0.31 .

[0039] Example 5: A high-yield zeolite-like vanadium molybdate catalyst with the molecular formula Mo 2.3 V1Te 0.02 O 14 Ni 0.31 , where Ni is divalent. The synthesis method of this catalyst includes the following steps: a) Mix 1.25 g of MoO3, 0.3415 g of V2O5, 0.01 g of TeO2, and 0.3108 g of NiSO4·6H2O in 25.00 mL of water, and add 0.2835 g of oxalic acid and 0.1969 g of citric acid as complexing agents to obtain a preliminary mixture. Add this preliminary mixture to an autoclave with a polytetrafluoroethylene lining, stir well, transfer it to a reactor, and continue stirring until it is evenly mixed to obtain a mixture; b) Transfer the obtained mixture to a reactor with a polytetrafluoroethylene lining, hydrothermally treat it at a temperature of 190 °C for 24 hours, and then slowly cool it to room temperature at room temperature to obtain an aqueous suspension containing the Mo 2.3 V1Te 0.02 O 14 Ni 0.31 compound; c) Extract and filter to obtain the solid in the aqueous suspension, dry it in an oven at 60 °C for 12 h, and the obtained solid product is the catalyst Mo2.3 V1Te 0.02 O 14 Ni 0.31 。

[0040] Example 6: High-yield zeolite-like vanadium molybdate catalyst, with the molecular formula Mo 2.3 V1Te 0.02 O 14 Cu 0.31 , where Cu is divalent. The synthesis method of this catalyst includes the following steps: a) Mix 1.25 g of MoO3, 0.3415 g of V2O5, 0.01 g of TeO2 and 0.2951 g of CuSO4·5H2O in 25.00 mL of water, and add 0.2835 g of oxalic acid and 0.1969 g of citric acid as complexing agents to obtain a preliminary mixture. Add this preliminary mixture to an autoclave with a polytetrafluoroethylene lining, stir well, then transfer it to a reactor and continue stirring until evenly mixed to obtain a mixture; b) Transfer the obtained mixture to a reactor with a polytetrafluoroethylene lining, hydrothermally treat it at a temperature of 190 °C for 24 hours, and then slowly cool it to room temperature at room temperature to obtain an aqueous suspension containing Mo 2.3 V1Te 0.02 O 14 Cu 0.31 compound; c) Extract and filter to obtain the solid in the aqueous suspension, dry it in an oven at 60 °C for 12 h, and the obtained solid product is the catalyst Mo 2.3 V1Te 0.02 O 14 Cu 0.31 。

[0041] Example 7: High-yield zeolite-like vanadium molybdate catalyst, with the molecular formula Mo 2.3 V1Te 0.2 O 14 Ni 0.47 , where Ni is divalent. The synthesis method of this catalyst includes the following steps: a) Mix 1.10 g of MoO3, 0.3015 g of V2O5, 0.1 g of TeO2 and 0.3108 g of NiSO4·6H2O in 25.00 mL of water, and add 0.2835 g of oxalic acid and 0.1969 g of citric acid as complexing agents to obtain a preliminary mixture. Add this preliminary mixture to an autoclave with a polytetrafluoroethylene lining, stir well, then transfer it to a reactor and continue stirring until evenly mixed to obtain a mixture; b) Transfer the obtained mixture to a reactor with a polytetrafluoroethylene lining, hydrothermally treat it at a temperature of 190 °C for 24 hours, and then slowly cool it to room temperature at room temperature to obtain an aqueous suspension containing Mo 2.3 V1Te 0.2 O 14 Ni0.47 An aqueous suspension of the compound; c) Filter the extraction to obtain the solid in the aqueous suspension, and dry it in an oven at 60 °C for 12 h. The obtained solid product is the catalyst Mo 2.3 V1Te 0.2 O 14 Ni 0.47 .

[0042] Comparative Example 1: Zeolite vanadomolybdate catalyst, with the molecular formula Mo3V1O 18 . The synthesis method of this catalyst includes the following steps: a) At room temperature, dissolve (NH4)6Mo7O 24 (7.270 g, 99%) and VOSO4·xH2O (2.570 g, 99%) separately in 105 mL of distilled water, and stir for 10 minutes to obtain two kinds of dissolved solutions; b) After mixing the two obtained dissolved solutions, continue to stir for 10 minutes, then adjust the pH value of the solution to 3.2, and pour the solution into a stainless steel autoclave with a polytetrafluoroethylene liner; c) Bubble N2 through the solution in the stainless steel autoclave for 10 minutes to remove O2 in the solution, then place the stainless steel autoclave in an oven and heat it at 175 °C for 48 hours to obtain a crude product; d) Filter and dry the crude product to obtain a solid crude product, and further purify it with oxalic acid; e) Add 1 g of the solid crude product purified with oxalic acid to 25 mL of an oxalic acid aqueous solution with a concentration of 0.4 mol / L, stir the solution at 60 °C for 30 minutes, then filter and wash the obtained solid with distilled water. The obtained solid is dried overnight in an oven at 80 °C, and the final product obtained is the catalyst Mo3V1O 18 .

[0043] Comparative Example 2: Zeolite vanadomolybdate catalyst, with the molecular formula Mo3V1O 18 Zn x (x = 0.2). The synthesis method of this catalyst includes the following steps: a) Dissolve 21.594 g of MoO3 (0.150 mol, 99.5%) in 33.2 mL of a 25 - 30% methylamine solution (methylamine: 0.210 - 0.251 mol) under continuous stirring. After MoO3 is completely dissolved, a gray - blue clear solution is obtained. Then place the obtained solution in a vacuum oven and evaporate and dry it under vacuum at 75 °C (p / p 0= 0.03) for 24 h to obtain a white solid powder. The white solid powder was dried overnight in an oven at 80 °C to obtain the product, named MAHM; b) Weigh 2.675 g of MAHM and dissolve it in 45 mL of distilled water, and stir for 10 minutes at room temperature to obtain a MAHM solution; Weigh 0.885 g of VOSO4 and dissolve it in 15 mL of distilled water, and stir for ten minutes at room temperature to obtain a VOSO4 solution; Pour the VOSO4 solution into the MAHM solution, stir for 10 minutes at room temperature, then add 1 mmol of zinc sulfate heptahydrate, continue to stir for 10 minutes, and then quickly carry out nitrogen (100 mL / min) bubbling for 10 minutes to obtain a reaction solution; c) Transfer the obtained reaction solution to a reaction kettle with a polytetrafluoroethylene lining, place the reaction kettle in an oven at 175 °C and react for 48 hours. After that, the reaction kettle is slowly cooled to room temperature at room temperature, and a crude product is obtained in the reaction kettle; d) Filter the crude product in the reaction kettle to obtain a solid product, dry it in an oven at 60 °C for 12 hours. After the dried sample is mixed with an oxalic acid solution with a concentration of 0.4 mol / L, stir it in a water bath at 60 °C for 30 minutes, wash it with 500 mL of distilled water, filter it, and dry the obtained solid in an oven at 80 °C for 12 hours. The final product obtained is the catalyst Mo3V1O 18 Zn x (x = 0.2).

[0044] Comparative Example 3: Zeolite vanadomolybdate catalyst, with the molecular formula Mo 2.3 V1Te 0.02 O 14 Ni 0.47 , where Ni is divalent. The synthesis method of this catalyst includes the following steps: a) Mix 1.10 g of MoO3, 0.3415 g of V2O5, 0.01 g of TeO2 and 0.3108 g of NiSO4·6H2O in 25.00 mL of water, and add 0.2835 g of oxalic acid and 0.1969 g of citric acid as complexing agents to obtain a preliminary mixture. Add this preliminary mixture to an autoclave with a polytetrafluoroethylene lining, stir well, and then transfer it to a reactor and continue to stir until it is evenly mixed to obtain a mixture; b) Transfer the obtained mixture to a reactor with a polytetrafluoroethylene lining, carry out hydrothermal treatment at a temperature of 190 °C for 24 hours, and then slowly cool it to room temperature at room temperature to obtain an aqueous suspension containing Mo 2.3 V1Te 0.02 O 14 Ni 0.47 compound; c) Extract and filter to obtain the solid in the aqueous suspension, dry it in an oven at 60 °C for 12 h, and the obtained solid product is the catalyst Mo 2.3 V1Te 0.02 O 14 Ni 0.47 .

[0045] Comparative Example 4: Zeolite vanadium molybdate catalyst, molecular formula Mo 2.3 V1O 14 Ni 0.47 , wherein Ni is divalent. The synthesis method of the catalyst comprises the following steps: a) mixing 1.10 g of MoO3, 0.3015 g of V2O5 and 0.3108 g of NiSO4·6H2O in 25.00 mL of water, and adding 0.2835 g of oxalic acid and 0.1969 g of citric acid as complexing agents to obtain a primary mixture, adding the primary mixture to an autoclave with a polytetrafluoroethylene liner, stirring thoroughly, transferring the mixture to a reactor and continuing stirring until the mixture is uniformly mixed to obtain a mixture; b) transferring the obtained mixture to a reactor with a polytetrafluoroethylene liner, hydrothermally treating the mixture at a temperature of 190°C for 24 hours, and then slowly cooling the mixture to room temperature to obtain a catalyst containing Mo. 2.3 V1O 14 Ni 0.47 c) extracting and filtering the solid in the aqueous suspension, and drying it in an oven at 60°C for 12h to obtain a solid product, which is the catalyst Mo 2.3 V1O 14 Ni 0.47 .

[0046] The catalysts prepared in the above Examples 1 to 6 are applied to Application Examples 1 to 6 of the catalytic oxygen oxidation ethane dehydrogenation reaction to produce ethylene, and the catalyst prepared in the above Example 7 is applied to Application Examples 7-1, 7-2, and 7-3 of the catalytic oxygen oxidation ethane dehydrogenation reaction to produce ethylene, and Application Examples 8 to 10 are added. Among them, Application Example 8 uses the catalyst prepared in Comparative Example 1, Application Example 9 uses the catalyst prepared in Comparative Example 2, and Application Example 10 uses the catalyst prepared in Comparative Example 3.

[0047] Application Examples 1 to 6: The amount of catalyst used is 0.5g. The catalytic oxygen oxidation ethane dehydrogenation to ethylene reaction is carried out in a fixed bed reactor under normal pressure. The reaction temperature is 300oC, and the total flow rate of the raw gas for the reaction is 50mL / min. The molar percentages of ethane and oxygen in the raw gas for the reaction are both 10%, and the rest is nitrogen. The raw gas is continuously introduced for 30 minutes to simulate the oxygen oxidation ethane dehydrogenation reaction. After the reaction is completed, the generated gas is introduced into a Shimadzu GC-2014c gas chromatograph for analysis. The C2H6 conversion rate and C2H4 selectivity of the six catalysts are combined for analysis and comparison. The results are shown in Table 1.

[0048] Application Example 8: The dosage of the catalyst is 0.5 g each. The catalytic oxidative dehydrogenation of ethane to ethylene reaction is carried out in a fixed-bed reactor under atmospheric pressure conditions. The reaction temperature is 260 - 310 °C, and the total flow rate of the reaction feed gas is 50 mL / min; the molar percentages of ethane and oxygen in the reaction feed gas are both 10%, and the rest is nitrogen. The feed gas is continuously introduced for 30 minutes to simulate the oxidative dehydrogenation of ethane reaction. After the reaction, the generated gas is introduced into a Shimadzu GC-2014c gas chromatograph for analysis. The CO x (x = 1, 2) conversion rate, C2H6 conversion rate, C2H4 selectivity, and C2H4 yield are analyzed and compared in combination, and the results are shown in Table 2.

[0049] Application Example 9: The dosage of the catalyst is 0.5 g each. The catalytic oxidative dehydrogenation of ethane to ethylene reaction is carried out in a fixed-bed reactor under atmospheric pressure conditions. The reaction temperature is 260 - 310 °C, and the total flow rate of the reaction feed gas is 50 mL / min; the molar percentages of ethane and oxygen in the reaction feed gas are both 10%, and the rest is nitrogen. The feed gas is continuously introduced for 30 minutes to simulate the oxidative dehydrogenation of ethane reaction. After the reaction, the generated gas is introduced into a Shimadzu GC-2014c gas chromatograph for analysis. The CO x (x = 1, 2) conversion rate, C2H6 conversion rate, C2H4 selectivity, and C2H4 yield are analyzed and compared in combination, and the results are shown in Table 3.

[0050] Application Example 7-1: The dosage of the catalyst is 0.5 g each. The catalytic oxidative dehydrogenation of ethane to ethylene reaction is carried out in a fixed-bed reactor under atmospheric pressure conditions. The reaction temperature is 260 - 310 °C, and the total flow rate of the reaction feed gas is 50 mL / min; the molar percentages of ethane and oxygen in the reaction feed gas are both 10%, and the rest is nitrogen. The feed gas is continuously introduced for 30 minutes to simulate the oxidative dehydrogenation of ethane reaction. After the reaction, the generated gas is introduced into a Shimadzu GC-2014c gas chromatograph for analysis. The CO x (x = 1, 2) conversion rate, C2H6 conversion rate, C2H4 selectivity, and C2H4 yield are analyzed and compared in combination, and the results are shown in Table 4.

[0051] Application Example 7-2: The catalyst dosages were divided into 5 types, namely 0.5 g, 0.4 g, 0.3 g, 0.2 g, and 0.1 g. The catalytic oxidative dehydrogenation of ethane to ethylene reaction was carried out in a fixed-bed reactor under atmospheric pressure conditions. The reaction temperature was 300 °C, and the total flow rate of the reaction feed gas was 50 mL / min; the molar percentages of ethane and oxygen in the reaction feed gas were both 10%, and the rest was nitrogen. The feed gas was continuously introduced for 30 minutes to simulate the oxidative dehydrogenation of ethane reaction. After the reaction ended, the generated gas was introduced into a Shimadzu GC-2014c gas chromatograph for analysis. The C2H6 conversion rate, C2H4 selectivity, and C2H4 yield of the 5 different catalyst dosages were combined for analysis and comparison, and the results are shown in Table 5.

[0052] Application Example 7-3: The catalyst dosage was 0.5 g. The catalytic oxidative dehydrogenation of ethane to ethylene reaction was carried out in a fixed-bed reactor under atmospheric pressure conditions. The reaction temperature was 280 - 330 °C, and the total flow rate of the reaction feed gas was 50 mL / min; the molar percentages of ethane and oxygen in the reaction feed gas were both 10%, and the rest was nitrogen. The feed gas was continuously introduced for 30 minutes to simulate the oxidative dehydrogenation of ethane reaction. After the reaction ended, the generated gas was introduced into a Shimadzu GC-2014c gas chromatograph for analysis. The C2H6 conversion rate and C2H4 selectivity of the catalyst were combined for analysis and comparison, and the results are shown in Figure 6 .

[0053] Application Example 10: The catalyst dosage was 0.5 g. The catalytic oxidative dehydrogenation of ethane to ethylene reaction was carried out in a fixed-bed reactor under atmospheric pressure conditions. The reaction temperature was 280 - 330 °C, and the total flow rate of the reaction feed gas was 50 mL / min; the molar percentages of ethane and oxygen in the reaction feed gas were both 10%, and the rest was nitrogen. The feed gas was continuously introduced for 30 minutes to simulate the oxidative dehydrogenation of ethane reaction. After the reaction ended, the generated gas was introduced into a Shimadzu GC-2014c gas chromatograph for analysis. The C2H6 conversion rate and C2H4 selectivity of the catalyst were combined for analysis and comparison, and the results are shown in Figure 6

[0054] Figure 1 XRD powder diffraction patterns and production diagrams of the catalysts of Examples 1 - 6. From Figure 1It can be seen that by adding MnSO4·H2O, FeSO4·7H2O, CoSO4·7H2O, NiSO4·6H2O and CuSO4·5H2O, the orthorhombic phase XRD diffraction characteristic peaks are located at 6.7°, 7.9°, 9.0°, 22.2°. This indicates that the incorporation of Mn, Fe, Co, Ni and Cu successfully synthesizes the M1 phase, and the catalyst has a high yield. Based on XRD analysis, the synthesized catalysts all have the same structural framework. This shows that this method is applicable to the synthesis of different transition metal ions incorporated. When Cr is added, the orthorhombic phase is not obtained, and the characteristic peaks at 12.8°, 23.4°, 25.7°, 27.4° and 39° are attributed to MoO3. Among Examples 1 to 6 with the addition of 6 different metal ions, Example 5 exhibits high crystallinity and purity, which indicates that Ni is the most suitable element for forming the catalyst and is therefore used as a model catalyst in the following research. In addition, by Figure 1 It can also be seen that the yields of the catalysts synthesized in Examples 1 to 6 can reach more than 80%.

[0055] Figure 2 XRD powder diffraction patterns and yield diagrams of the catalysts of Example 7, Comparative Example 1 and Comparative Example 2 are shown. The yield of the catalyst in Comparative Example 1 is only 10%, and the waste of a large amount of raw materials leads to an increase in cost. Comparative Example 2 is doped with Zn metal, and the yield only reaches 16%. Compared with Comparative Example 1 and Comparative Example 2, the yield of the catalyst synthesized in Example 7 has been greatly increased to 80%. The XRD patterns of these 3 catalysts are the same, indicating that the catalysts prepared by different methods have the same crystal structure.

[0056] Figure 3 XRD powder diffraction patterns of the catalysts of Example 7 and Comparative Example 4 are shown. The catalyst in Comparative Example 4 does not contain Te element, and its XRD pattern does not show the MoVO orthorhombic phase and there are amorphous phase impurities, while Example 7 with the addition of a trace amount of 0.1 g of Te element has a complete orthorhombic phase, proving that the presence of Te element is crucial for the synthesis of the catalyst.

[0057] Figure 4 CO2 adsorption-desorption isotherms of the catalysts of Example 7 and Comparative Example 3 are shown. The CO2 adsorption amount of Comparative Example 3 with a Te content of 0.01 g is significantly less than that of Example 7 with a Te content of 0.1 g, indicating that the change in Te content has a great impact on the pore size, and the Te content can significantly affect the adsorption capacity of the catalyst and does not block the pores.

[0058] Figure 5 CO2 adsorption-desorption isotherms of the catalysts of Example 7, Comparative Example 1 and Comparative Example 2 are shown. The CO2 adsorption amount of Example 7 is greater than that of Comparative Example 2 and Comparative Example 1, indicating that the doping of Te and Ni does not block the micropores of the catalyst.

[0059] Figure 6 Conversion rate graph (A) of C2H6 and selectivity graph (B) of C2H4 for the catalysts of Application Example 7-3 and Application Example 10. Through comparison, it can be seen that the catalytic effect of the catalyst with 0.1 g of Te content in Application Example 7-3 has been greatly improved compared to the catalyst with 0.01 g of Te content in Application Example 10. The catalyst in Application Example 7-3 can reach a conversion rate of 62% at a relatively low reaction temperature of 290 °C, while the catalyst in Application Example 10 only has a conversion rate of 24%, indicating that the Te element has a crucial impact on the catalytic effect, which is consistent with Figure 3 、 Figure 4 the results.

[0060] Figure 7 XPS spectra of the Mo(3d) signal for Example 7 and Comparative Example 3; Figure 8 XPS spectra of the V(2p) signal for Example 7 and Comparative Example 3; Figure 9 XPS spectra of the O(1s) signal for Example 7 and Comparative Example 3; Figure 10 XPS spectra of the Te(3d) signal for Example 7 and Comparative Example 3; Figure 11 XPS spectra of the Ni(2p) signal for Example 7 and Comparative Example 3.

[0061] By comparing Application Examples 1-6 in Table 1, it can be found that the catalyst doped with metal Ni in Application Example 5 has the best catalytic performance.

[0062] By comparing Application Example 8, Application Example 9 and Application Example 7-1 in Tables 2-4, the performance of the catalysts was tested. It can be clearly seen from Table 4 that at 280 °C, the conversion rate of C2H6 is 34.08% and the selectivity of C2H4 is 93%; when the temperature rises to 290 °C, the activity of the catalyst increases sharply, the conversion rate of C2H6 reaches 69.78%, and the selectivity of C2H4 drops to 72.51%. Further increasing the temperature has little effect on the activity of the catalyst. Compared with Comparative Examples 1 and 2 synthesized by the metal salt method, the Mo 2.3 V1Te 0.2 O 14 Ni 0.47 catalyst of Example 7 has the same orthorhombic structure but is more active throughout the reaction temperature range.

[0063] By comparing the catalyst dosages of Application Example 7-2 in Table 5, it can be found that increasing the catalyst dosage can improve the reaction activity, and the ethylene selectivity will also decrease accordingly. The ethylene yield is the highest when the catalyst dosage is 0.5 g.

[0064] The performance test methods in Tables 1-5: The catalyst reaction path judgment method for dehydrogenating ethane to ethylene by oxygen oxidation using reaction performance includes two major steps:

[0065] I. The specific reaction steps are as follows:

[0066] (1) Weigh 0.5 g of the catalyst with a particle size of 20 - 30 mesh and place it in the middle of the quartz reaction tube. Then place the quartz reaction tube in a fixed - bed reactor and heat it.

[0067] (2) Under different pretreatment atmospheres, heat it to the required reaction temperature at a heating rate of 10 °C / min.

[0068] (3) Introduce the raw material gas for the reaction. The raw material gas for the reaction consists of C2H6:O2:N2 = 5:5:40. To ensure the stable gas flow of the raw material gas for the reaction, after purging for thirty minutes, then conduct sampling and testing.

[0069] (4) Under atmospheric pressure, the mixed gas after the reaction passes through a pipeline and a filter and then enters a gas chromatograph (Shimadzu GC - 2014c) for on - line analysis. The detectors are FID and TCD detectors. To ensure the accuracy and repeatability of the test data, three repeated experiments are conducted at each reaction temperature.

[0070] (5) After the experiment, purge the pipeline system with N2. After evacuating the reaction mixed gas, turn off the power supply.

[0071] II. The calculation methods for the conversion rates of each reactant and the selectivities of each product are as follows: C2H6 conversion (C2H6 conversion), C2H4 yield (C2H4 yield), C2H4 selectivity (C2H4 selectivity), and CO x selectivity (CO x selectivity, x = 1, 2) are calculated according to the following formulas.

[0072]

[0073] Table 1

[0074]

[0075] Table 2

[0076]

[0077] Table 3

[0078]

[0079]

[0080] Table 4

[0081]

[0082] Table 5

[0083]

Claims

1. A high-yield zeolite-like vanadomolybdate catalyst, characterized in that, The molecular formula of the catalyst is Mo a V f Te b O c M d , where M is one of the transition metal elements Cr, Mn, Fe, Co, Ni, Cu, and a, b, c, d, f are all molar ratios, a = 2 - 3, b = 0 - 0.2, c = 10 - 20, d = 0.2 - 0.5, f = 1. The catalyst uses the Mo-V-O composite framework material as the main active component and M as the co-catalytic component.

2. The high-yield zeolite vanadium molybdate catalyst according to claim 1, characterized in that, M is one of trivalent Cr, divalent Mn, divalent Fe, divalent Co, divalent Ni, and divalent Cu.

3. The synthesis method of the high-yield zeolite vanadium molybdate catalyst according to any one of claims 1-2, characterized in that, It includes the following steps: a) Prepare starting compounds containing molybdenum, vanadium, and tellurium, and add a metal salt of M and a complexing agent to the starting compounds to obtain a mixture, where the complexing agent is used to regulate the ionic concentration of the solution, and the molar ratio of the complexing agent to the metal salt of M is 1:(1 - 2); b) Hydrothermally treat the mixture obtained in step a) at a temperature of 150 to 200 °C for 24 to 48 hours to obtain an aqueous suspension containing a Mo a V f Te b O c M d compound; c) Separate and obtain the solid in the aqueous suspension obtained in step b), and dry it at a temperature of 60 to 150 °C. The obtained solid product is the catalyst Mo a V f Te b O c M d 。 4. The synthesis method of a high-yield zeolite-like vanadium molybdate catalyst according to claim 3, characterized in that, In step a), the metal salt of M is one of chromium sulfate, manganese sulfate, iron sulfate, cobalt sulfate, nickel sulfate, and copper sulfate.

5. The synthesis method of a high-yield zeolite-like vanadium molybdate catalyst according to claim 3, characterized in that, In step a), the starting compounds include a molybdenum-containing compound, a vanadium-containing compound, and a tellurium-containing compound. The molybdenum-containing compound is ammonium heptamolybdate or molybdenum trioxide, the vanadium-containing compound is vanadyl sulfate or vanadium pentoxide, and the tellurium-containing compound is tellurium dioxide.

6. The synthesis method of a high-yield zeolite-like vanadium molybdate catalyst according to claim 3, characterized in that, In step a), the complexing agent is oxalic acid and citric acid, and the molar ratio of oxalic acid to citric acid is (1 - 5):

1.

7. Use of the high-yield zeolite vanadium molybdate catalyst according to any one of claims 1 - 2 in the reaction of catalytic oxidative dehydrogenation of ethane to ethylene with oxygen.

8. The application according to claim 7, wherein The application method is: after granulating the high-yield zeolite vanadium molybdate catalyst, conduct the reaction of catalytic oxidative dehydrogenation of ethane to ethylene with oxygen in a fixed-bed reactor under atmospheric pressure.

9. The application according to claim 8, wherein The particle size of the granulated high-yield zeolite vanadium molybdate catalyst is 20 - 60 mesh, and the reaction temperature of the reaction of catalytic oxidative dehydrogenation of ethane to ethylene with oxygen is 250 - 330 °C.

10. The application according to claim 9, characterized in that, In the reaction of catalytic oxidative dehydrogenation of ethane to ethylene with oxygen, the dosage of the high-yield zeolite vanadium molybdate catalyst is 0.1 - 0.5 g, the total flow rate of the reaction feed gas is 30 - 80 mL / min, the molar percentages of ethane and oxygen in the reaction feed gas are both 10%, and the rest is nitrogen.

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