Copper-based catalyst for preparing acetaldehyde through ethanol dehydrogenation as well as preparation method and application of copper-based catalyst

Abstract

The invention discloses a copper-based catalyst for preparing acetaldehyde through ethanol dehydrogenation as well as a preparation method and application of the copper-based catalyst. The preparation method comprises the following steps: S1, carrying out alkalization treatment on protic mordenite in a strong alkali solution to increase the number of surface hydroxyl groups of the protic mordenite; and S2, adding the mordenite obtained in the step S1 into a copper salt solution to load copper ions, and then sequentially carrying out low-temperature drying shaping and medium-temperature activation stages to obtain the copper-based catalyst with networked Cu-OH-Si-O bonds on the surface. Through the synergistic effect of alkali liquor regulation and control and staged oxygen roasting, the dispersity and stability of a Cu active center in the catalyst are improved, the acetaldehyde selectivity of the reaction of preparing acetaldehyde through ethanol dehydrogenation is also improved, and side reactions are inhibited. Carrying out heat treatment regeneration on the inactivated copper-based catalyst in an oxygen-containing atmosphere; and after regeneration, the networked Cu-OH-Si-O bond on the surface of the copper-based catalyst is reconstructed.

Description

Technical Field

[0001] This invention relates to the field of dehydrogenation reaction catalyst technology, and specifically to a copper-based catalyst for the dehydrogenation of ethanol to acetaldehyde, its preparation method, and its applications. Background Technology

[0002] Currently, the dehydrogenation of ethanol to acetaldehyde and hydrogen mainly employs metal-based catalysts, with typical systems including copper-based, platinum-based, and nickel-based catalysts. Among these, copper-based catalysts are considered the most industrially promising system due to their low cost, abundant resources, and good dehydrogenation activity. In existing technologies, common copper-based catalysts are usually supported on metal oxides (such as Al2O3, SiO2, ZnO) or molecular sieves (such as ZSM-5, MFI, MOR), prepared by impregnation or ion exchange methods. Copper-based catalysts supported on mordenite (MOR) have the following characteristics: the MOR molecular sieve has a one-dimensional channel structure, which can provide a spatial confinement effect and improve the dispersion of copper active centers; the zeolite framework contains Brønsted acid sites, which can promote the adsorption and activation of ethanol molecules; the catalyst is usually calcined at high temperature to form CuO active centers (or Cu... 2+ (Active center), which is then reduced to Cu during the reaction or pretreatment stage. + / Cu 0 Active center. Existing mordenite-based copper-based catalysts have the following drawbacks:

[0003] (1) Poor catalyst stability

[0004] Copper active sites are prone to agglomeration or sintering during the reaction, leading to a reduction in the number of active sites. This is mainly because most reported ethanol dehydrogenation reactions occur at around 300°C, where copper nanoparticles tend to grow. At the same time, the hydroxyl groups on the support surface and the hydrothermal environment may induce the Oersted ripening process, accelerating the aggregation of copper particles.

[0005] (2) Insufficient selectivity

[0006] The strongly acidic sites on the surface of MOR molecular sieves readily promote intramolecular or intermolecular dehydration side reactions in ethanol, generating ethylene and secondary hydrocarbon active centers, thus reducing acetaldehyde selectivity. This is because the excessive number of Brønsted acid centers competes for the dehydrogenation pathway of the ethanol molecule.

[0007] (3) Limitations of regeneration methods

[0008] Existing technologies typically use a hydrogen atmosphere for regeneration, which has the following problems:

[0009] ① Hydrogen is a flammable and explosive gas, posing a high risk in industrial operations;

[0010] ② Hydrogen reduction often fails to completely remove carbon deposits or fully restore Cu.2+ The lack of active sites results in limited regeneration effects.

[0011] (4) The interaction of water molecules has not been properly utilized.

[0012] Studies have shown that water molecules can regulate the adsorption / desorption behavior of intermediates and inhibit carbon deposition. However, the adsorption capacity of water molecules on the surface of traditional catalysts is limited, and they easily lose stability at high temperatures. This is because the unmodified molecular sieve surface only exhibits weak adsorption of water molecules, making it difficult to maintain a synergistic effect under reaction conditions.

[0013] Therefore, improving the dispersion and stability of Cu active centers and the selectivity of acetaldehyde in mordenite-based copper catalysts while suppressing side reactions remains an urgent technical problem to be solved. Summary of the Invention

[0014] Due to the aforementioned deficiencies in the existing technology, this invention provides a copper-based catalyst for the dehydrogenation of ethanol to acetaldehyde, its preparation method, and its applications. Through the synergistic effect of alkaline control and staged oxygen roasting, a networked Cu-OH-Si-O structure is constructed in situ on the surface of the mordenite-based copper-based catalyst. This not only improves the dispersion and stability of Cu active centers but also enhances the acetaldehyde selectivity of the ethanol dehydrogenation to acetaldehyde reaction and suppresses side reactions.

[0015] To achieve the above objectives, in a first aspect, the present invention provides a method for preparing a copper-based catalyst for the dehydrogenation of ethanol to acetaldehyde, comprising the following steps:

[0016] Step S1: Alkaliize the proton-type mordenite in a strong alkaline solution to increase the number of surface hydroxyl groups of the proton-type mordenite.

[0017] Step S2: Add the mordenite obtained in step S1 to a copper salt solution to load copper ions, and then perform low-temperature drying and shaping and medium-temperature activation stages in sequence to obtain a copper-based catalyst with networked Cu-OH-Si-O bonds on the surface.

[0018] The processing temperature during the low-temperature drying and shaping stage should not exceed 120℃. During this stage, Cu... 2+ It forms a Cu-(OH)2 complex with the hydroxyl groups on the surface of mordenite;

[0019] The temperature of the intermediate-temperature activation stage is 250~350℃, and the treatment atmosphere is oxygen. During this stage, networked Cu-OH-Si-O bonds are generated on the surface of the copper-based catalyst.

[0020] The above technical solution weakens strong acid sites and introduces surface hydroxyl groups through alkali modification, thereby regulating the acidity / alkalinity and pore structure of zeolite and improving the dispersion and stability of Cu active centers. It also enhances acetaldehyde selectivity and suppresses side reactions by synergistically constructing a networked Cu-OH-Si-O bond through alkali modification and staged calcination, and maintaining the stability of this network under high-temperature conditions. A two-stage calcination process of "low-temperature shaping—medium-temperature activation" is employed: a Cu-(OH)2 surface complex is formed at low temperature to achieve initial anchoring of copper active centers and hydroxyl groups; subsequently, medium-temperature calcination in an oxygen atmosphere controls the Cu... 2+ The dispersion and oxidation state ratios form highly dispersed Cu-OH-Si-O bonds that are covalently bonded to the support.

[0021] Furthermore, the treatment with the strong alkaline solution is to weaken the strong acid sites of the zeolite and introduce surface hydroxyl groups. The solute of the strong alkaline solution can be an alkali metal or alkaline earth metal, such as KOH, LiOH, Ca(OH)2, etc., with a concentration of not less than 0.5M.

[0022] As a better technical solution, the strong alkaline solution is a 1M NaOH aqueous solution.

[0023] Furthermore, the solute in the copper salt solution is one of the soluble copper salts such as copper nitrate, copper chloride, and copper sulfate.

[0024] Furthermore, the copper loading is 1 to 10 wt%. For example, the copper loading is 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, or 10 wt%.

[0025] As a better technical solution, the copper loading is 5 wt%.

[0026] Secondly, the present invention provides a copper-based catalyst, which is prepared by the preparation method described above; the surface of the copper-based catalyst contains networked Cu-OH-Si-O bonds, and water molecules are adsorbed on the surface to form a water complex network structure under the reaction conditions of ethanol dehydrogenation to acetaldehyde above 200°C.

[0027] Furthermore, after the copper-based catalyst is deactivated in the ethanol dehydrogenation reaction, the deactivated copper-based catalyst is regenerated by heat treatment in an oxygen-containing atmosphere; after regeneration, the networked Cu-OH-Si-O bonds on the surface of the copper-based catalyst are reconstructed.

[0028] As a better technical solution, the deactivated copper-based catalyst is regenerated by treating it at 300°C for 1 hour in an O2 / Ar mixed atmosphere.

[0029] Thirdly, the present invention provides an application of the copper-based catalyst described above in the ethanol dehydrogenation to acetaldehyde industry.

[0030] Compared with the prior art, the above invention has the following advantages or beneficial effects:

[0031] (1) Innovative surface structure design and microstructure optimization induced by two-stage calcination

[0032] The preparation method of this invention constructs a highly dispersed, covalently bonded network of Cu-OH-Si-O bonds on the surface of a copper-based catalyst through synergistic alkali modification and staged calcination. This achieves a stable surface water complex structure at temperatures above 200°C, which assists in the desorption of reaction intermediates and inhibits carbon deposition. This is a previously undisclosed support regulation strategy. The combined low-temperature shaping and high-temperature activation control of Cu... 2+ The ratio of active centers to oxidized states is adjusted to prevent high-temperature reduction or agglomeration, significantly improving anti-sintering performance.

[0033] (2) Oxygen atmosphere regeneration and structural self-repair with high selectivity and long life performance

[0034] The copper-based catalyst of this invention exhibits significantly improved acetaldehyde selectivity and enhanced reaction stability due to the synergistic effect of optimized support acidity and surface water complexation. Simultaneously, the Cu-OH-Si-O bond network can be reconstructed through the oxygen regeneration process, combining carbon removal and activity restoration functions, thus overcoming the limitations of traditional reduction regeneration. Furthermore, the acetaldehyde selectivity and conversion rate can be restored to over 90% after regeneration. Attached Figure Description

[0035] The invention, its features and advantages will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings.

[0036] Figure 1 In one embodiment of the present invention, the copper-based catalyst was used at 150-225°C and a weight hourly space velocity (WHSV) of 1.52 h⁻¹. -1 Ethanol dehydrogenation activity test curve under the specified conditions;

[0037] Figure 2 This is a graph showing the ethanol conversion rate and product selectivity of a copper-based catalyst under different weight hourly space velocities at 225°C in one embodiment of the present invention.

[0038] Figure 3 In one embodiment of the present invention, the copper-based catalyst was subjected to a reaction at 225°C and a weight hourly space velocity of 1.52 h⁻¹. -1 Graphs showing the changes in ethanol conversion rate and acetaldehyde yield over time;

[0039] Figure 4 The infrared (IR) spectra of the copper-based catalyst adsorbing ethanol at 40°C and different adsorption times in one embodiment of the present invention are shown.

[0040] Figure 5This is an in-situ DRIFTS (diffuse reflectance Fourier transform infrared spectrum) image of the surface active centers of the copper-based catalyst changing with temperature during ethanol desorption in one embodiment of the present invention. Detailed Implementation

[0041] The structure of the present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the invention. Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It will also be understood that, unless expressly defined herein, terms such as those defined in a general dictionary shall be interpreted as having the meaning consistent with their meaning in the relevant field context, and not as having an ideal or overly formal meaning.

[0042] In a first aspect, the present invention provides a method for preparing a copper-based catalyst for the dehydrogenation of ethanol to acetaldehyde, comprising the following steps:

[0043] Step S1: The proton-type mordenite zeolite is alkalized in a strong alkaline solution to increase the number of surface hydroxyl groups. Proton-type mordenite zeolite (H-MOR) is selected as the support because its one-dimensional channels and moderate acidity are conducive to the directional adsorption and conversion of ethanol molecules. For example, H-MOR is placed in a NaOH solution and stirred for several hours, filtered, and washed until neutral to obtain NaMOR. This treatment weakens the strong Brønsted acid sites of the mordenite zeolite, increases the number of surface hydroxyl groups (-OH), and regulates the acid-base distribution. After NaOH modification, the hydroxyl groups on the support surface can form a stable hydrogen bond network with the residual Brønsted acid sites. In the subsequent copper loading and oxygen calcination process, this network interacts with Cu... 2+ The active center further forms a Cu-OH-Si-O structure, exhibiting a "surface water complex structure" that can be maintained even at high temperatures.

[0044] The treatment with the strong alkaline solution is to weaken the strong acid sites of the zeolite and introduce surface hydroxyl groups. The solute of the strong alkaline solution can be an alkali metal or alkaline earth metal, such as KOH, LiOH, Ca(OH)2, etc., with a concentration of not less than 0.5M.

[0045] Step S2: The mordenite obtained in step S1 is added to a copper salt solution to load copper ions, followed by low-temperature drying and medium-temperature activation stages to obtain a copper-based catalyst with a network of Cu-OH-Si-O bonds on its surface. More specifically, a calculated amount of Cu(NO3)2·2.5H2O is dissolved in deionized water, and NaMOR is added and stirred until homogeneous. Besides copper nitrate, copper chloride, copper sulfate, and other soluble copper salts can also be used as the solute in the copper salt solution.

[0046] The processing temperature during the low-temperature drying and shaping stage should not exceed 120℃. During this stage, Cu... 2+ The copper-based catalyst forms a Cu-(OH)2 complex with the hydroxyl groups on the surface of the mordenite zeolite. The intermediate-temperature activation stage is conducted at 250–350 °C in an oxygen atmosphere. During this stage, a network of Cu-OH-Si-O bonds forms on the surface of the copper-based catalyst, resulting in highly dispersed Cu. 2+ Active center.

[0047] This "two-stage + oxygen roasting" process effectively prevents the aggregation of copper active centers, Cu 2+ The particle size of the active centers was controlled below 3 nm. The formation of Cu-OH-Si-O bonds enhanced the Cu... 2+ The electronic coupling between the active center and the support improves the stability of the redox cycle.

[0048] In some embodiments, the copper loading is optimized between 1–10 wt% to balance activity and stability. For example, copper loadings are 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, or 10 wt%. As a more preferred implementation, the copper loading is 5 wt%.

[0049] Secondly, this invention provides a copper-based catalyst, prepared using the method described above. The surface of the copper-based catalyst contains networked Cu-OH-Si-O bonds, and under the conditions of ethanol dehydrogenation to acetaldehyde reaction at temperatures above 200°C, water molecules are adsorbed on the surface to form a water-rich complex network structure. This structure stabilizes the Cu produced in the reaction. + / Cu 2+ The active site enhances the selectivity of acetaldehyde in the ethanol dehydrogenation reaction and inhibits carbon deposition through a synergistic adsorption-desorption effect. In-situ DRIFTS verification showed that this surface water complex network structure remains stable at 200–250 °C.

[0050] After the copper-based catalyst is deactivated in the ethanol dehydrogenation reaction, it is regenerated by heat treatment in an oxygen-containing atmosphere. After regeneration, the networked Cu-OH-Si-O bonds on the surface of the copper-based catalyst are reconstructed. In this process, oxygen can both remove carbon deposits and rebuild the Cu-OH-Si-O network, thereby restoring the surface water complex structure.

[0051] As a superior technical solution, the deactivated copper-based catalyst is regenerated by treating it at 300°C for 1 hour in an O2 / Ar mixed atmosphere. After regeneration, the acetaldehyde selectivity is restored to over 90%, and the activity remains basically stable. Compared with traditional hydrogen regeneration, oxygen regeneration avoids the risk of flammable gases and has higher safety and operability.

[0052] Thirdly, this invention provides an application of the copper-based catalyst described above in the ethanol dehydrogenation to acetaldehyde industry. The catalyst of this invention, used in the ethanol dehydrogenation reaction (CH3CH2OH → CH3CHO + H2), exhibits the following characteristics at 200-250°C: acetaldehyde selectivity >90%; and its activity can be fully recovered after regeneration. This catalytic system is superior to existing technologies in terms of structure, regeneration mechanism, and reaction synergy.

[0053] As described above, this invention utilizes the synergistic effect of alkaline control and staged oxygen calcination to construct a stable Cu-OH-Si-O complex structure in situ on the surface of Cu-alkali-treated mordenite zeolite. Specifically, this involves: first, treatment with NaOH solution to generate stable hydroxyl groups on the zeolite surface and weaken strong Brønsted acid sites; then, low-temperature drying (≤120℃) to fix the -OH sites, followed by medium-temperature oxygen calcination (250-350℃) to induce the formation of a Cu-OH-Si-O network; this network can still adsorb a certain number of water molecules to form a "surface water complex structure" under dehydrogenation reaction conditions above 200℃. This structure stabilizes Cu... 2+ On the one hand, it prevents the species from being reduced or agglomerated at high temperatures; on the other hand, it allows water molecules to exist in a complexed state, assisting in the desorption of reaction intermediates and inhibiting carbon deposition.

[0054] This invention employs a two-stage calcination process: low-temperature shaping followed by high-temperature activation. At low temperature, a Cu-(OH)₂ surface complex is formed, achieving initial anchoring of copper species with hydroxyl groups. Subsequently, high-temperature calcination is performed in an oxygen atmosphere to control the Cu content. 2+ The dispersion and oxidation state ratio are optimized to form a highly dispersed Cu-O-Si-O network that is covalently bonded to the support. This staged process, in conjunction with the oxygen environment, significantly improves the dispersion of Cu species (particle size <3 nm) and delays high-temperature sintering. Existing literature only discloses conventional single-stage calcination and does not address the synergistic effect of low-temperature hydroxyl fixation and high-temperature oxidation, thus demonstrating significant inventiveness.

[0055] This invention proposes for the first time an integrated strategy of "oxygen regeneration + surface water network protection". The deactivated catalyst is regenerated at 300℃ in an O2 / Ar atmosphere, which not only thoroughly removes carbon but also reconstructs the Cu-OH-Si-O structure during the regeneration process, allowing the surface water complex network to be restored. This method considers the synergistic regeneration mechanism of the surface water complex network and active centers, avoiding the risk of hydrogen reduction. Furthermore, the acetaldehyde selectivity and conversion rate can be restored to over 90% after regeneration, demonstrating reversibility and structural stability.

[0056] The mordenite, solute, and solvent involved in the following effect examples are all commercially available, as are the magnetic stirrer, muffle furnace, and other reaction apparatus. The methods of use are existing technologies that can be found.

[0057] In the following examples, the reactor used for testing the ethanol dehydrogenation reaction employed a specially designed plug-flow reactor with a cooling spiral structure to improve heat exchange efficiency and a 3 mm diameter bypass pipe. During the experiment, 50 mg of catalyst was weighed and packed into the reaction tube. Ethanol was added to an 8 sccm argon carrier gas stream at a rate of 0.5 μL / min (controlled by a Harvard Pump 11 Elite syringe pump) and then introduced into the reactor. The reaction products were vaporized and detected using a Dycor LCD200 mass spectrometer, with the ^36Ar signal used as an internal standard for signal normalization.

[0058] Example

[0059] This embodiment provides a method for preparing a copper-based catalyst and its application in the ethanol dehydrogenation reaction.

[0060] First, commercially available H-type mordenite zeolite (HMOR, model NKF-12-25JS) was selected as the carrier. 10 g of HMOR was added to 100 mL of a 1 mol / L NaOH aqueous solution, and the mixture was magnetically stirred at room temperature for 12 hours. After the reaction was complete, the resulting solid was repeatedly washed with deionized water until the washing solution was neutral, yielding alkali-treated mordenite NaMOR.

[0061] Secondly, copper was loaded using an impregnation method. 0.182 g of Cu(NO3)2·2.5H2O (purchased from Sigma-Aldrich Chemistry Co.) was weighed and dissolved in 1.5 g of deionized water to obtain an impregnation solution. 1 g of NaMOR was added to this impregnation solution and stirred until a homogeneous mixture was formed. The resulting sample was dried overnight at 100 °C and then calcined in a muffle furnace at 300 °C for 12 hours to obtain a Cu-NaMOR catalyst with a loading of 5 wt.%. Following the same method, X wt.% Cu-NaMOR (X = 1, 2, ..., 10) could be prepared by adjusting the amount of copper salt.

[0062] The following section will use the obtained 5 wt.% Cu-NaMOR catalyst as an example to test the ethanol dehydrogenation reaction. Other copper-based catalysts with different loadings exhibit slightly inferior catalytic and regeneration performance, but all are superior to catalysts without copper loading.

[0063] See Figure 1 and Figure 2The Cu-NaMOR catalyst has an activation temperature of 170℃, an ethanol conversion rate exceeding 55%, 100% selectivity for hydrogen in the gas phase products (yield of 0.12 μmol / s), and 100% selectivity for acetaldehyde in the liquid phase products (yield of 0.052 μmol / s). See also... Figure 3 After 5 hours of reaction, both the ethanol conversion rate and the acetaldehyde yield decreased by approximately 20%. The catalyst was then regenerated by treating it at 300 °C under an O2 / Ar atmosphere for 1 hour. Experiments continued after regeneration.

[0064] See Figure 4 The IR spectrum of Cu-NaMOR adsorbing ethanol at 40℃ shows a peak at 1630 cm⁻¹. -1 and 3661 cm -1 The negative peaks appearing at the catalyst surface are attributed to the loss of water molecules, indicating that water molecules were already present on the catalyst surface before ethanol adsorption. These negative peaks become more pronounced with increasing ethanol adsorption time, suggesting that ethanol molecules may have replaced surface moisture or facilitated the migration of water molecules to other locations, leading to the appearance of the negative peaks. The source of these water molecules is likely related to the interaction between the acidic sites of HMOR and sodium hydroxide.

[0065] See Figure 5 In situ infrared spectra of catalyst surface species changes with temperature during ethanol desorption show that, with increasing temperature, the species at 1630 cm⁻¹... -1 The intensity of the negative peak characteristic of water gradually weakens and eventually stabilizes. This indicates that after ethanol molecules desorb from the catalyst surface or react, water molecules return to their original positions.

[0066] The experimental results above show that this invention, through the synergistic effect of alkaline control and staged oxygen roasting, constructs a stable Cu-OH-Si-O complex structure in situ on the surface of Cu-alkali-treated mordenite. This network can still adsorb a certain number of water molecules to form a "surface water complex structure" under dehydrogenation reaction conditions above 200℃. This structure stabilizes Cu... 2+ On the one hand, it prevents the species from being reduced or agglomerated at high temperatures; on the other hand, it allows water molecules to exist in a complexed state, assisting in the desorption of reaction intermediates and inhibiting carbon deposition. The existence of this stable water complex network was verified by in-situ DRIFTS experiments, representing a novel, non-obvious structural control method. Regeneration of the deactivated catalyst under an O2 / Ar atmosphere at 300℃ not only resulted in thorough carbon removal but also enabled the reconstruction of the Cu-OH-Si-O structure during the regeneration process, thus restoring the surface water complex network.

[0067] Those skilled in the art should understand that variations can be implemented by combining existing technology with the above embodiments, which will not be elaborated here. Such variations do not affect the essence of the present invention, and will not be elaborated here either.

[0068] The preferred embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and the devices and structures not described in detail should be understood as being implemented in a conventional manner in the art. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the scope of the present invention. This does not affect the essential content of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the present invention's technical solutions still fall within the protection scope of the present invention.

Claims

1. A method for preparing a copper-based catalyst for the dehydrogenation of ethanol to acetaldehyde, characterized in that, Includes the following steps: Step S1: Alkaliize the proton-type mordenite in a strong alkaline solution to increase the number of surface hydroxyl groups of the proton-type mordenite. Step S2: Add the mordenite obtained in step S1 to a copper salt solution to load copper ions, and then perform low-temperature drying and shaping and medium-temperature activation stages in sequence to obtain a copper-based catalyst with networked Cu-OH-Si-O bonds on the surface. The processing temperature during the low-temperature drying and shaping stage should not exceed 120℃. During this stage, Cu... 2+ It forms a Cu-(OH)2 complex with the hydroxyl groups on the surface of mordenite; The temperature of the intermediate-temperature activation stage is 250~350℃, and the treatment atmosphere is oxygen. During this stage, networked Cu-OH-Si-O bonds are generated on the surface of the copper-based catalyst.

2. The method for preparing a copper-based catalyst for the dehydrogenation of ethanol to acetaldehyde according to claim 1, characterized in that, The solute in the strong alkaline solution is an alkali metal or alkaline earth metal, and the concentration is not less than 0.5M.

3. The method for preparing a copper-based catalyst for the dehydrogenation of ethanol to acetaldehyde according to claim 2, characterized in that, The strong alkaline solution is a 1M NaOH aqueous solution.

4. The method for preparing a copper-based catalyst for the dehydrogenation of ethanol to acetaldehyde according to claim 1, characterized in that, The solute in the copper salt solution is one of copper nitrate, copper chloride, or copper sulfate.

5. The method for preparing a copper-based catalyst for the dehydrogenation of ethanol to acetaldehyde according to claim 1, characterized in that, The copper loading is 1~10 wt%.

6. The method for preparing a copper-based catalyst for the dehydrogenation of ethanol to acetaldehyde according to claim 5, characterized in that, The copper loading is 5 wt%.

7. A copper-based catalyst, characterized in that, The copper-based catalyst is prepared by any one of the preparation methods described in claims 1 to 6; the surface of the copper-based catalyst contains networked Cu-OH-Si-O bonds, and water molecules are adsorbed on the surface to form a water complex network structure under the reaction conditions of ethanol dehydrogenation to acetaldehyde above 200°C.

8. The copper-based catalyst according to claim 7, characterized in that, After the copper-based catalyst is deactivated in the ethanol dehydrogenation reaction, the deactivated copper-based catalyst is regenerated by heat treatment in an oxygen-containing atmosphere; after regeneration, the networked Cu-OH-Si-O bonds on the surface of the copper-based catalyst are reconstructed.

9. The copper-based catalyst according to claim 8, characterized in that, The deactivated copper-based catalyst was regenerated by treatment at 300°C for 1 hour in an O2 / Ar mixed atmosphere.

10. The application of the copper-based catalyst according to any one of claims 7 to 9 in the ethanol dehydrogenation to acetaldehyde industry.

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