Oxide catalyst for preparing acetaldehyde and hydrogen by anaerobic dehydrogenation of ethanol and its preparation method and application

Abstract

The application discloses an oxide catalyst for preparing acetaldehyde and hydrogen through ethanol anaerobic dehydrogenation, a preparation method and application thereof, and belongs to the technical field of catalysts. The oxide catalyst for preparing acetaldehyde and hydrogen through ethanol anaerobic dehydrogenation is a single oxide or a composite oxide. The oxide catalyst component serves as a carrier or an active component. The oxide catalyst component contains two or three of zinc oxide, aluminum oxide, zirconium oxide and magnesium oxide. A reaction raw material is configured into a precursor solution according to a certain metal atom molar ratio. A precipitating agent is added dropwise into the solution under severe stirring to adjust the pH of the mixed solution. The mixture is stirred and aged to obtain an intermediate material. The intermediate material is filtered, dried and ground to obtain a powder. The powder is calcined in a muffle furnace to obtain the catalyst. The catalyst has the advantages of convenient operation, improved production efficiency, reduced cost, green environmental protection and sustainable development.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to an oxide catalyst for the oxygen-free dehydrogenation of ethanol to produce acetaldehyde and hydrogen, its preparation method, and its application. Background Technology

[0002] The overuse of fossil fuels has triggered a series of ecological problems, prompting a deeper exploration of sustainable energy solutions. Biomass energy, as the only renewable carbon-containing energy source, has become a research hotspot. It can not only reduce dependence on fossil resources but also lower the carbon footprint by producing carbon-neutral chemical products and fuels. Ethanol, as an easily accessible biomass energy source, not only provides a wide range of raw material sources but also has an ample supply. Furthermore, through a series of catalytic dehydrogenation reactions, ethanol can be converted into a variety of high-value-added chemical products, offering an effective solution to alleviate the fossil fuel shortage. The process of producing acetaldehyde from ethanol via anaerobic dehydrogenation not only achieves high atom utilization but also, as a key intermediate in the catalytic conversion of ethanol, acetaldehyde is of paramount importance for enhancing the high-value conversion of ethanol.

[0003] Currently, Cu-based catalysts are the most widely studied type in the research of oxygen-free dehydrogenation of ethanol, attracting much attention due to their excellent catalytic activity. However, copper-based catalysts are prone to sintering and coke deposition, leading to deactivation. Irreversible sintering during the reaction reduces activity and selectivity because catalyst particle polymerization at high temperatures reduces active sites, thereby decreasing catalytic efficiency. For example, Patent Document No. 201210349547.3 discloses a method for preparing a catalyst using the sol-gel method, with at least one of SiO2, Al2O3, or ZrO2 as a support and Cu as the active component. Additionally, Patent Document No. 201711285838.X discloses a catalyst for the direct dehydrogenation of ethanol to acetaldehyde, with ZnTa2O6 as the active component and SiO2 and / or activated carbon as the support. However, since tantalum is a rare and expensive metal, the extraction and preparation of tantalum pentoxide is costly; this may be a limiting factor for large-scale industrial applications. Patent document number 201910769571.4 discloses a catalyst for the direct dehydrogenation of ethanol to acetaldehyde, the active component of which contains Cu and boron compounds. To address this issue, patent number 201710908602.0 discloses a catalyst with the composition Au / AxByCuzOn (where A is a non-variable valence metal ion and B is a variable valence metal ion). This catalyst utilizes a simple two-step low-temperature combustion-calcination method to efficiently synthesize a support. By controlling the type and composition of the metal elements, the surface properties of the support can be modulated, enhancing the synergistic catalytic effect between the gold nanoparticles and the support, achieving stable and efficient gas-phase selective oxidation of ethanol to acetaldehyde. This invention solves the problems of carbon deposition and sintering; however, precious metals are expensive, and their reserves on Earth are limited, restricting not only extraction and supply but also significantly increasing costs for large-scale industrial applications.

[0004] Therefore, there is a need to provide an oxide catalyst for the oxygen-free dehydrogenation of ethanol to produce acetaldehyde and hydrogen, as well as its preparation method and application, in order to solve the above-mentioned problems. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide an oxide catalyst for the oxygen-free dehydrogenation of ethanol to produce acetaldehyde and hydrogen, its preparation method, and its application, thereby solving the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] An oxide catalyst for the oxygen-free dehydrogenation of ethanol to produce acetaldehyde and hydrogen includes a catalyst, wherein the catalyst is a single oxide or a composite oxide, and the oxide catalyst component serves as a support or active component, wherein the oxide catalyst component contains two or three of zinc oxide, aluminum oxide, zirconium oxide and magnesium oxide.

[0008] As a further aspect of the present invention, the raw material for the catalyst is one or more of zinc nitrate, aluminum nitrate, zirconium nitrate, and magnesium nitrate.

[0009] As a further embodiment of the present invention, when the metal elements in the catalyst are Zn and Al / Mg, the molar ratio is 0.5-1:1; when the metal elements in the catalyst are Zn and Zr, the molar ratio is 5-35:95-65; and when the metal elements in the catalyst are Zn, Zr and Al, the molar ratio is 1:4:2-8.

[0010] A method for preparing an oxide catalyst for the oxygen-free dehydrogenation of ethanol to acetaldehyde and hydrogen, characterized by comprising the following steps:

[0011] Step S1: Prepare a precursor solution by mixing the reaction raw materials according to a certain metal atomic molar ratio. Under vigorous stirring, add the precipitant dropwise into the solution to adjust the pH of the mixed solution. Stir and age the mixture to obtain the intermediate material.

[0012] Step S2: Filter, dry and grind the intermediate material obtained in step S1 to obtain powder;

[0013] Step S3: Calcine the powder obtained in step S2 in a muffle furnace to obtain the catalyst.

[0014] As a further embodiment of the present invention, the reaction raw materials in step S1 are one or more of zinc nitrate, aluminum nitrate, zirconium nitrate, and magnesium nitrate.

[0015] As a further embodiment of the present invention, the precipitant in step S1 is a 1 mol / L sodium carbonate solution or a 0.75 mol / L ammonium carbonate solution.

[0016] As a further embodiment of the present invention, the drying temperature in step S2 is 80-100℃ and the drying time is 8-12h.

[0017] As a further embodiment of the present invention, the calcination temperature in the muffle furnace in step S3 is 450-500℃, and the calcination time is 3-4h.

[0018] An oxide catalyst for the preparation of acetaldehyde and hydrogen from ethanol using anaerobic dehydrogenation.

[0019] As a further aspect of the present invention, the reaction conditions for the preparation of acetaldehyde and hydrogen by the oxide catalyst in the oxygen-free dehydrogenation of ethanol are as follows: under the conditions of a reaction temperature of 250-340℃ and a reaction pressure of 0.1-2MPa, ethanol is passed into a reactor carrying the oxide catalyst to directly dehydrogenate and produce acetaldehyde.

[0020] In summary, the embodiments of the present invention have the following beneficial effects compared with the prior art:

[0021] 1. This invention utilizes oxides, which are abundant and inexpensive raw materials, for the oxygen-free dehydrogenation of ethanol to produce acetaldehyde and hydrogen, enabling large-scale production and reducing the overall cost of the catalyst. This is particularly important for industrial applications, especially since cost control is one of the key factors in large-scale production.

[0022] 2. The catalyst described in this invention not only does not produce harmful byproducts in the process of ethanol dehydrogenation to produce acetaldehyde and hydrogen, but also generates high-value hydrogen energy. Its green catalytic characteristics meet the requirements of current sustainable development and environmental protection.

[0023] 3. The preparation method of the catalyst described in this invention is simple, can be carried out at low temperature and normal pressure, and does not require complex equipment or high energy consumption;

[0024] 4. The catalyst described in this invention has a large specific surface area and active sites, which can provide more reaction sites, thus exhibiting high catalytic activity.

[0025] To more clearly illustrate the structural features and effects of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0026] Figure 1 The image shows the XRD pattern of the ZnO-Al2O3 catalyst in the embodiments of the invention.

[0027] Figure 2 The nitrogen adsorption characterization spectrum of the ZnO-Al2O3 catalyst in the embodiments of the invention is shown.

[0028] Figure 3 The image shows the XRD pattern of the ZnO-MgO catalyst in the embodiments of the invention.

[0029] Figure 4 The nitrogen adsorption characterization spectrum of the ZnO-MgO catalyst in the embodiments of the invention is shown.

[0030] Figure 5 The image shows the XRD pattern of the ZnO-ZrO2 catalyst in the embodiments of the invention.

[0031] Figure 6 The nitrogen adsorption characterization spectrum of the ZnO-ZrO2 catalyst in the embodiments of the invention is shown.

[0032] Figure 7 The XRD patterns of the ZnO catalyst in the embodiments of the invention are shown after no pretreatment, H2 pretreatment, and N2 pretreatment.

[0033] Figure 8 The images show the H2-TPR spectra of the ZnO catalyst in the embodiments of the invention after no pretreatment, H2 pretreatment, and N2 pretreatment.

[0034] Figure 9 The XPS spectra of the ZnO catalyst in the embodiments of the invention are shown after no pretreatment and H2 pretreatment.

[0035] Figure 10 The XANES spectra of the ZnO catalyst in the embodiments of the invention are shown after no pretreatment and H2 pretreatment. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0037] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0038] In this invention, the catalyst is a single oxide or a composite oxide, wherein the catalyst is represented as A(x)B(y) or A(x)B(y)C(z), and the oxide catalyst contains two or three of ZnO, Al2O3, ZrO2 and MgO, and the molar ratio of the metal elements is x:y or x:y:z.

[0039] In Example 1, this example provides a single oxide catalyst for the preparation of acetaldehyde from ethanol by oxygen-free dehydrogenation, wherein the catalyst is Zn(1)Al(0), and the molar ratio of Zn to Al is 1:0.

[0040] The preparation method of Zn(1)Al(0) is as follows:

[0041] (1) Add 29.75g of Zn(NO3)2·6H2O to 100mL of water to prepare a 1mol / L solution and stir for 15min;

[0042] (2) Add 1 mol / L Na2CO3 solution dropwise to the solution in (1) as a precipitant, adjust the pH of the mixed solution to 10, stir and age the mixture for 3 hours and filter it;

[0043] (3) The precipitate obtained in step (2) is dried at 100℃ for 12 hours, then taken out and ground.

[0044] (4) Finally, the powder obtained in step (3) is calcined in a muffle furnace at 450°C for 4 hours to obtain a catalyst, denoted as Zn(1)Al(0).

[0045] The activity evaluation of Zn(1)Al(0) is as follows:

[0046] Anhydrous ethanol was used as a raw material to carry out ethanol dehydrogenation reaction in a fixed-bed reactor. The reaction conditions were as follows: 1 g of catalyst was packed in the fixed-bed reactor, the reaction pressure was 0.1 MPa, the reaction temperature was 320 °C, the flow rate of ethanol was 0.06 mL / h, and the flow rate of N2 carrier gas was 20 mL / min. After the reaction stabilized, the liquid products were analyzed by offline gas chromatography with an FID detector. The reaction results are shown in Table 1.

[0047] In Example 2, this example provides a composite oxide catalyst for the preparation of acetaldehyde from ethanol by oxygen-free dehydrogenation. The catalyst is composed of ZnO and Al2O3, and the catalyst is represented as Zn(0.5)Al(1), wherein the molar ratio of Zn to Al is 0.5:1.

[0048] The preparation method of Zn(0.5)Al(1) is as follows:

[0049] (1) Add 9.92g of Zn(NO3)2·6H2O and 25.01g of Al(NO3)3·9H2O to 100mL of water to prepare a 1mol / L solution and stir for 15min;

[0050] (2) Add 1 mol / L Na2CO3 solution dropwise to the solution in (1) as a precipitant, adjust the pH of the mixed solution to 10, stir and age the mixture for 3 hours and filter it;

[0051] (3) The precipitate obtained in step (2) is dried at 100℃ for 12 hours, then taken out and ground.

[0052] (4) Finally, the powder obtained in step (3) is calcined in a muffle furnace at 450°C for 4 hours to obtain the catalyst, which is represented as Zn(0.5)Al(1).

[0053] The activity evaluation of Zn(0.5)Al(1) is as follows:

[0054] Ethanol dehydrogenation was carried out in a fixed-bed reactor using anhydrous ethanol as a raw material. The reaction conditions were as follows: 1 g of catalyst was packed into the fixed-bed reactor, the reaction pressure was 0.1 MPa, the reaction temperature was 320 °C, the flow rate of ethanol was 0.06 mL / h, and the flow rate of N2 carrier gas was 20 mL / min. After the reaction stabilized, the liquid products were analyzed by offline gas chromatography with an FID detector. The reaction results are shown in Table 1.

[0055] In Examples 3-8, following the preparation methods provided in Examples 1-2, a series of zinc-based composite oxide catalysts were prepared by changing the types of raw materials and the molar ratio of metal atoms. The relevant performance tests were then conducted, and the results are shown in Table 1.

[0056] In Example 9, this example provides a single oxide catalyst for the preparation of acetaldehyde from ethanol by oxygen-free dehydrogenation, the catalyst being represented as Zn(0)Zr(100), wherein the molar ratio of Zn to Al is 0:100.

[0057] The preparation method of Zn(0)Zr(100) is as follows:

[0058] (1) Prepare 50 mL of 0.6 mol / L zirconium nitrate solution by dissolving 12.88 g of Zr(NO3)4·5H2O at 70℃ and stirring for 15 min;

[0059] (2) Add 0.75 mol / L (NH4)2CO3 solution dropwise to the solution in (1) as a precipitant, adjust the pH of the mixed solution to 7, stir and age the mixture for 3 hours and filter it;

[0060] (3) The precipitate obtained in step (2) is dried at 100℃ for 12 hours, then taken out and ground.

[0061] (4) Finally, the powder obtained in step (3) is calcined in a muffle furnace at 500°C for 3 hours to obtain a catalyst denoted as ZrO2.

[0062] The activity evaluation of Zn(0)Zr(100) is as follows:

[0063] Anhydrous ethanol was used as a raw material to carry out ethanol dehydrogenation reaction in a fixed-bed reactor. The reaction conditions were as follows: 1 g of catalyst was packed in the fixed-bed reactor, the reaction pressure was 0.1 MPa, the reaction temperature was 320 °C, the flow rate of ethanol was 0.06 mL / h, and the flow rate of N2 carrier gas was 20 mL / min. After the reaction stabilized, the liquid products were analyzed by offline gas chromatography with an FID detector. The reaction results are shown in Table 1.

[0064] In Example 10, this example provides a composite oxide catalyst for the preparation of acetaldehyde from ethanol by oxygen-free dehydrogenation. The catalyst is composed of ZnO and ZrO2, and the catalyst is represented as Zn(5)Zr(95), wherein the molar ratio of Zn to Al is 5:95.

[0065] The preparation method of Zn(5)Zr(95) is as follows:

[0066] (1) Prepare 50 mL of 0.6 mol / L zirconium nitrate solution by mixing 0.45 g of Zn(NO3)2·6H2O and 12.24 g of Zr(NO3)4·5H2O at 70℃ and stirring for 15 min.

[0067] (2) Add 0.75 mol / L (NH4)2CO3 solution dropwise to the solution in (1) as a precipitant, adjust the pH of the mixed solution to 7, stir and age the mixture for 3 hours and filter it;

[0068] (3) The precipitate obtained in step (2) is dried at 100℃ for 12 hours, then taken out and ground.

[0069] (4) Finally, the powder obtained in step (3) is calcined in a muffle furnace at 500°C for 3 hours to obtain the catalyst denoted as Zn(5)Zr(95).

[0070] The activity evaluation of Zn(5)Zr(95) is as follows:

[0071] Anhydrous ethanol was used as a raw material to carry out ethanol dehydrogenation reaction in a fixed-bed reactor. The reaction conditions were as follows: 1 g of catalyst was packed in the fixed-bed reactor, the reaction pressure was 0.1 MPa, the reaction temperature was 320 °C, the flow rate of ethanol was 0.06 mL / h, and the flow rate of N2 carrier gas was 20 mL / min. After the reaction stabilized, the liquid products were analyzed by offline gas chromatography with an FID detector. The reaction results are shown in Table 1.

[0072] In Examples 11-16, following the preparation methods provided in Examples 9-10 above, a series of composite oxide catalysts were prepared by changing the molar ratio of zinc nitrate and zirconium nitrate or zinc nitrate, aluminum nitrate and zirconium nitrate, and relevant performance tests were conducted. The results are shown in Table 1.

[0073] Table 1 shows the correspondence between ethanol dehydrogenation activity and selectivity in the examples.

[0074]

[0075]

[0076] In addition, the present invention explored the preparation conditions of composite oxide catalysts, and representative work is described in Examples 17-24.

[0077] In Example 17, this example provides a single oxide catalyst for the preparation of acetaldehyde from ethanol by oxygen-free dehydrogenation, the catalyst being represented as Zn(1)Al(0), wherein the molar ratio of Zn to Al is 1:0.

[0078] Applications of the catalyst Zn(1)Al(0), i.e., ZnO:

[0079] Anhydrous ethanol was used as a raw material to carry out ethanol dehydrogenation reaction in a fixed-bed reactor. The reaction conditions were as follows: 1 g of catalyst was packed in the fixed-bed reactor, the reaction pressure was 0.1 MPa, the reaction temperature was 250 °C, the flow rate of ethanol was 0.06 mL / h, and the flow rate of N2 carrier gas was 20 mL / min. After the reaction stabilized, the liquid products were analyzed by offline gas chromatography with an FID detector. The reaction results are shown in Table 2.

[0080] In Examples 18-19, following the activity evaluation method provided in Example 17, the ZnO catalyst was subjected to relevant performance tests at different reaction temperatures of 280°C and 350°C. The results are shown in Table 2.

[0081] Table 2. Correspondence between ethanol dehydrogenation activity and selectivity on ZnO catalysts at different temperatures.

[0082] Example Reaction temperature / °C Selectivity of acetaldehyde / % Ethanol conversion rate / % 17 250 23.99 89.74 18 280 35.29 86.13 1 320 42.55 86.88 19 350 29.21 79.26

[0083] In Example 20, this example provides a single oxide catalyst for the preparation of acetaldehyde from ethanol by oxygen-free dehydrogenation, the catalyst being represented as Zn(1)Al(0), wherein the molar ratio of Zn to Al is 1:0.

[0084] Applications of the catalyst Zn(1)Al(0), i.e., ZnO:

[0085] Anhydrous ethanol was used as a raw material to carry out ethanol dehydrogenation reaction in a fixed-bed reactor. The reaction conditions were as follows: 1 g of catalyst was packed in the fixed-bed reactor, the reaction pressure was 0.5 MPa, the reaction temperature was 320 °C, the flow rate of ethanol was 0.06 mL / h, and the flow rate of N2 carrier gas was 20 mL / min. After the reaction stabilized, the liquid products were analyzed by offline gas chromatography with an FID detector. The reaction results are shown in Table 3.

[0086] In Examples 21-22, following the activity evaluation method provided in Example 20 above, the ZnO catalyst was subjected to relevant performance tests under different reaction pressures of 1 MPa and 2 MPa. The results are shown in Table 3.

[0087] Table 3. Correspondence between ethanol dehydrogenation activity and selectivity on ZnO catalysts under different pressures.

[0088]

[0089]

[0090] In Example 23, this example provides a single oxide catalyst for the preparation of acetaldehyde from ethanol by oxygen-free dehydrogenation, the catalyst being represented as Zn(1)Al(0), wherein the molar ratio of Zn to Al is 1:0.

[0091] Applications of the catalyst Zn(1)Al(0), i.e., ZnO:

[0092] Anhydrous ethanol was used as a raw material for ethanol dehydrogenation in a fixed-bed reactor. Before the reaction, the ZnO catalyst was treated at 450℃ for 1 h under 10% H2 / Ar conditions. The treated catalyst was denoted as ZnO(H2). The reaction conditions were as follows: 1 g of catalyst was loaded into the fixed-bed reactor, the reaction pressure was 0.1 MPa, the reaction temperature was 320℃, the flow rate of ethanol was 0.06 mL / h, and the flow rate of N2 carrier gas was 20 mL / min. After the reaction stabilized, the liquid products were analyzed by offline gas chromatography with an FID detector. The reaction results are shown in Table 4.

[0093] In Example 24, following the activity evaluation method provided in Example 23 above, ZnO was treated in a N2 atmosphere at 450°C for 1 hour by changing the pretreatment conditions. The resulting catalyst was denoted as ZnO(N2), and relevant performance tests were performed. The results are shown in Table 4.

[0094] Table 4. Correspondence between ethanol dehydrogenation activity and selectivity on ZnO catalysts under different reaction conditions.

[0095] Example Catalyst pretreatment conditions Selectivity of acetaldehyde / % Ethanol conversion rate / % 1 No pretreatment 42.55 86.88 23 <![CDATA[H2, treated at 450 °C for 1 h]]> 80.43 10.11 24 <![CDATA[N2, treated at 450°C for 1 h]]> 78.18 10.10

[0096] In Test Example 1, the X-ray diffraction patterns of the zinc-aluminum composite oxide catalysts prepared in Examples 1-4 are shown below. Figure 1 ,observe Figure 1 It can be seen that when the molar ratio of Zn to Al is 0.5:1, the formation of cubic spinel-type ZnAl₂O₄ is beneficial to improving the ethanol conversion rate; Figure 2 As can be seen from the nitrogen adsorption-desorption isotherm, all of these samples have a mesoporous structure;

[0097] In Example 2, the X-ray diffraction patterns of the zinc-magnesium composite oxide catalyst products prepared in Examples 5-8 are shown below. Figure 3 ,Depend on Figure 3 It can be seen that the diffraction peaks of the composite material are not sharp, indicating that ZnO and MgO are uniformly dispersed in the Zn-Mg composite material; from Figure 4 As can be seen from the nitrogen adsorption-desorption isotherm, all of these samples have a mesoporous structure;

[0098] In Example 3, the X-ray diffraction patterns of the zinc-zirconium composite oxide catalysts prepared in Examples 9-13 are shown below. Figure 5 ,Depend on Figure 5 It was found that when the molar ratio of Zn to Zr was 20:80 and 5:95, respectively, the tetragonal zinc-zirconium composite oxide contributed to the improvement of ethanol conversion rate; Figure 6 As can be seen from the nitrogen adsorption-desorption isotherm, all of these samples have a mesoporous structure;

[0099] In test example 4, the X-ray diffraction patterns of the catalyst products prepared in Examples 1 and 23-24 are shown below. Figure 7 ,observe Figure 7 It can be seen that the crystal structure of ZnO remains stable; Figure 8 The H2-TPR spectrum confirmed that oxygen vacancies were formed in the ZnO catalyst after H2 and N2 pretreatment; Figure 9 In the figure, the ratio of oxygen atoms Oα in the crystal lattice to oxygen atoms Oβ adsorbed on surface oxygen defect sites changes from 1:0.73 to 1:0.86, indicating an increase in the relative area of ​​oxygen defects. To further verify the existence of oxygen defects, Figure 10 The XANES spectrum provides information on the microscopic electronic structure of ZnO material before and after high-temperature reduction pretreatment. At the rising edge of the XANES spectrum, there is a significant energy shift. The edge of ZnO after high-temperature reduction treatment shifts to a lower energy position. This shift is caused by the transition from a high oxidation state to a low reduction state, which further proves the loss of oxygen in ZnO.

[0100] In summary, this invention presents an oxide catalyst for the oxygen-free dehydrogenation of ethanol to produce acetaldehyde and hydrogen. The catalyst is synthesized using a simple co-precipitation method, which is convenient to operate, lowering the technical threshold and improving production efficiency, thus facilitating industrial applications. This catalyst not only has potential applications in the oxygen-free dehydrogenation of ethanol to produce acetaldehyde and hydrogen, but also, due to the abundant raw material resources and low price of zinc-based composite oxides, can be produced on a large scale, effectively reducing catalyst costs and having significant implications for industrial applications. Furthermore, this catalyst produces no harmful byproducts, meeting green catalysis standards, further highlighting its advantages in sustainable development and environmental friendliness.

[0101] The above description is only a preferred embodiment 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. A method for preparing an oxide catalyst for the oxygen-free dehydrogenation of ethanol to acetaldehyde and hydrogen, characterized in that, Includes the following steps: Step S1: Prepare a precursor solution by mixing the reaction raw materials with an atomic molar ratio of Zn, Zr, and Al of 1:4:

4. Under vigorous stirring, add the precipitant dropwise into the solution to adjust the pH of the mixed solution. Stir and age the mixture to obtain the intermediate material. Step S2: Filter, dry and grind the intermediate material obtained in step S1 to obtain powder; Step S3: Calcine the powder obtained in step S2 in a muffle furnace to obtain the oxide catalyst; The oxide catalyst comprises zinc oxide, aluminum oxide, and zirconium oxide.

2. The method for preparing the oxide catalyst for the oxygen-free dehydrogenation of ethanol to acetaldehyde and hydrogen according to claim 1, characterized in that, The reaction raw materials in step S1 are zinc nitrate, aluminum nitrate, and zirconium nitrate.

3. The method for preparing the oxide catalyst for the oxygen-free dehydrogenation of ethanol to acetaldehyde and hydrogen according to claim 1, characterized in that, The precipitant in step S1 is a 1 mol / L sodium carbonate solution or a 0.75 mol / L ammonium carbonate solution.

4. The method for preparing the oxide catalyst for the oxygen-free dehydrogenation of ethanol to acetaldehyde and hydrogen according to claim 1, characterized in that, The drying temperature in step S2 is 80-100℃, and the drying time is 8-12h.

5. The method for preparing the oxide catalyst for the oxygen-free dehydrogenation of ethanol to acetaldehyde and hydrogen according to claim 1, characterized in that, The calcination temperature in the muffle furnace in step S3 is 450-500℃, and the calcination time is 3-4h.

6. The application of the oxide catalyst prepared by the method according to any one of claims 1-5 in the preparation of acetaldehyde and hydrogen by oxygen-free dehydrogenation of ethanol.

7. The application according to claim 6, characterized in that, The reaction conditions for the preparation of acetaldehyde and hydrogen by the oxide catalyst in the oxygen-free dehydrogenation of ethanol are as follows: under the conditions of reaction temperature of 250-340℃ and reaction pressure of 0.1-2MPa, ethanol is passed into a reactor carrying the oxide catalyst to directly dehydrogenate and produce acetaldehyde.

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