Preparation method of high-dispersion supported CuNi alloy catalyst rich in hydroxyl groups on surface

Abstract

The invention discloses a preparation method of a high-dispersion supported CuNi alloy catalyst rich in hydroxyl groups on the surface. The preparation method comprises the following steps: by taking Cu salt and Ni salt as active metal sources, Zr salt, Al salt, Ti salt and the like as carrier metal sources and urea and other electron-rich organic matters containing heteroatoms as spacer chelating agents, slowly and orderly dispersing and growing adjacent Cu and Ni species on the surface of the carrier metal under the action of water to generate ordered and controllable mixed metal salt precipitates, and then washing, drying and reducing at high temperature to obtain the Cu-Ni-Cu-Ni composite material. And finally, the high-dispersion supported CuNi alloy catalyst rich in hydroxyl groups on the surface is obtained. According to the invention, a highly dispersed CuNi alloy structure is formed by adopting a direct reduction mode, so that the CuNi alloy has excellent substrate activation capability, and 85% of high ethanol selectivity in total alcohol can be realized in a catalytic CO2 hydrogenation process. The method has the advantages of simple preparation process, low cost and the like, and has industrial application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalyst synthesis, and particularly relates to a highly dispersed supported CuNi alloy catalyst with a hydroxyl-rich surface, a preparation method thereof, and its application in the catalytic hydrogenation of CO2 to ethanol. Background Art

[0002] Since the Industrial Revolution, fossil fuels such as coal, oil, and natural gas have been rapidly consumed. Currently, the total global demand for fossil fuels is still over 80%. The use of fossil fuels causes the annual emission of more than 30 billion tons of carbon dioxide into the environment. The large amount of CO2 emissions exacerbates the greenhouse effect, leading to global environmental problems such as global warming, glacier melting, and sea-level rise. Therefore, converting CO2 into high-value-added chemical products such as alcohols, olefins, and aromatics is of great significance for improving global climate change, reducing the huge dependence on fossil fuels, and turning waste into treasure.

[0003] Ethanol is an important chemical product, widely used in fields such as the chemical industry, medical industry, food industry, and agricultural production. In view of this, the highly selective conversion of CO2 into ethanol is a very valuable topic. However, CO2 is a thermodynamically stable and chemically inert linear molecule with a bond energy of 799 kJ / mol and a C=O dissociation energy of 532 kJ / mol, resulting in the need for relatively high energy for CO2 conversion. On the other hand, the high energy barrier of the C-C coupling reaction in this reaction makes it difficult to occur, resulting in the formation of C1 products such as CO, methane, and methanol; secondly, the C-C coupling reaction is difficult to precisely control and is prone to generating other C2 products (such as ethylene, acetaldehyde, acetic acid, etc.), resulting in low ethanol selectivity. Therefore, although a large number of catalysts have been reported for the hydrogenation of CO2 to ethanol, there are still generally problems of low CO2 conversion rate and low ethanol selectivity. For example, the Cu-Co / alumina catalyst reported in patent CN 118988318A has a total alcohol selectivity of only about 40%, and the highest selectivity of ethanol in the total alcohol can only reach 60%; the PdCu / CeO2 catalyst reported in patent CN108927156A is used for the selective hydrogenation of alkynes, but the high price of the precious metals used limits its practical application. Summary of the Invention

[0004] Aiming at the above problems existing in the prior art, the present invention provides a highly dispersed supported CuNi alloy catalyst with a hydroxyl-rich surface and a preparation method thereof. It uses non-precious metals Cu and Ni as alloy components, and utilizes the "chelation effect" and "precipitation effect" competition mechanism of alkaline chelating agents and the selective reduction process to prepare a highly dispersed supported CuNi alloy catalyst with a hydroxyl-rich surface. When it is used for the catalytic hydrogenation of CO2 to ethanol, a high ethanol selectivity of 85% in the total alcohol can be achieved.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A highly dispersed supported CuNi alloy catalyst with a surface rich in hydroxyl groups uses Cu salts and Ni salts as active metal sources. Under the action of water, the "spacer anchoring" and "selective adsorption" mechanisms of the spacer chelating agent are utilized to construct adjacent Cu and Ni species, and the adjacent Cu and Ni species are slowly and orderly dispersed and grown on the surface of the support metal through the competition mechanism of "chelating effect" and "precipitation effect" generated by the spacer chelating agent and its hydrolysis, thereby generating an orderly and controllable mixed metal salt precipitate. After filtration, washing, and drying, a mixed metal salt precursor is obtained. Then, the precursor is directly subjected to high-temperature reduction without calcination. The spacer chelating agent is used to in-situ remove organic small molecules such as H2O, NH3, and CO2 and generate active surface hydroxyl groups to assist the CO2 activation and intermediate product formation in the subsequent catalytic process, and the active metals are selectively reduced in combination with the metal activity sequence, so as to retain ZrO2, etc. as the support, and a highly dispersed supported CuNi alloy catalyst with a surface rich in hydroxyl groups is obtained.

[0006] The preparation of the highly dispersed supported CuNi alloy catalyst with a surface rich in hydroxyl groups specifically includes the following steps: 1) Dissolve Cu salts, Ni salts, and the support metal salt sufficiently in a solvent, and add a spacer chelating agent, and generate a mixed metal salt precipitate by heating and stirring; 2) Filter, wash, and dry the mixed metal salt precipitate obtained in step 1) to obtain a mixed metal salt precursor; 3) Subject the mixed metal salt precursor obtained in step 2) to high-temperature reduction to obtain a highly dispersed supported CuNi alloy catalyst with a surface rich in hydroxyl groups.

[0007] Further, the Cu salt is a nitrate, hydrochloride, sulfate, and / or acetate of copper.

[0008] Further, the Ni salt is a nitrate, hydrochloride, sulfate, and / or acetate of nickel.

[0009] Further, the support metal salt is a nitrate, hydrochloride, sulfate, and / or acetate of one or more of Zr, Al, and Ti.

[0010] Further, the spacer chelating agent is an electron-rich organic compound containing heteroatoms, specifically one or more of urea, thiourea, and carbonyldiimidazole, and preferably urea.

[0011] Further, in step 1), the solvent is deionized water or a mixture of it and one or more of methanol, ethanol, and acetonitrile, and the volume ratio of deionized water is 10 - 100%, and preferably deionized water.

[0012] Further, the dosage of the metal salt used in step 1) relative to the solvent is 0.01 - 50 mol / L, where Cu accounts for 0 - 60% of the total metal molar amount, and Ni accounts for 0 - 60% of the total metal molar amount.

[0013] Further, the dosage of the spacer chelating agent used in step 1) relative to the solvent is 0.01 - 50 mol / L.

[0014] Further, the temperature of the heating and stirring in step 1) is 25 - 300 °C, and the time is 0.1 - 72 h.

[0015] Further, the temperature of the drying in step 2) is 60 - 300 °C.

[0016] Further, the high-temperature reduction in step 3) is carried out in an H2 / N2 mixed gas atmosphere containing 1% - 100% H2 at 100 - 800 °C for 0.5 - 72 h.

[0017] From the perspective of the electronic structure of CO2 itself, its electron cloud is highly concentrated at the oxygen atom end, endowing this end with significant electronegativity, enabling it to be activated by electron-deficient materials; while the carbon atom end is positively charged and can thus be activated by electron-rich materials. Based on this property, selective activation of CO2 can be achieved by constructing materials with electron-deficient or electron-rich structures. For C-C coupling, usually oxygen-containing intermediates (such as CO, CH x O, etc.) and deeply hydrogenated intermediates (such as CH x etc.) are required to exist, and the two intermediates couple C-C at adjacent sites. Cu, as a metal with mild hydrogenation ability, can effectively fix oxygen-containing intermediates such as C(H) x O, etc. Ni is a metal with strong hydrogenation ability and can provide a large amount of dissociated H, which helps to generate deeply hydrogenated intermediates such as CH x etc. Further regulating the distance between Cu and Ni metals to form an alloy can promote the C(H) x O and CH xCoupling then generates ethanol. In addition, the catalytic activity of CO2 hydrogenation is affected by the alloy dispersion. Higher catalytic activity can be obtained by using a support that can highly disperse the alloy. Metal oxides have easily adjustable surface properties. They can disperse bimetals through metal bonds or metal-oxygen bonds, and can obtain surface hydroxyl groups by regulating the surface electron distribution of metal oxides to assist in activating CO2-based intermediates for generation. Based on this, the highly dispersed supported CuNi alloy catalyst with a hydroxyl-rich surface in the present invention not only has the function of fixing and activating CO2, but also can generate two different intermediates, providing adjacent active sites for C-C coupling, thereby achieving a high CO2 conversion rate and ethanol selectivity. After reduction by hydrogen, the catalyst forms a highly dispersed CuNi alloy. The formation of the alloy provides adjacent Cu and Ni sites, making it easier for the oxygen-containing intermediates fixed by Cu and the deeply hydrogenated intermediates generated by Ni to undergo C-C coupling and further hydrogenation to generate ethanol. Therefore, the obtained highly dispersed supported CuNi alloy catalyst with a hydroxyl-rich surface is suitable for catalyzing the hydrogenation of CO2 to ethanol.

[0018] Furthermore, the application method is to load the highly dispersed supported CuNi alloy catalyst with a hydroxyl-rich surface into a batch autoclave reactor, and simultaneously charge a CO2 / H2 / Ar mixed gas to carry out the reaction of hydrogenating CO2 to prepare ethanol.

[0019] Even further, the dosage of the catalyst is 10 - 1000 mg, the reaction solvent is 0 - 100 mL of 1,4-dioxane, the reaction pressure is 0.1 - 4 MPa, the reaction time is 0.5 - 48 h, and the reaction temperature is 25 - 300 °C.

[0020] The beneficial effects of the present invention are as follows: (1) The highly dispersed supported CuNi alloy catalyst with a hydroxyl-rich surface prepared in the present invention activates CO2 with the help of surface hydroxyl groups. The adjacent Cu and Ni sites in the CuNi alloy provide two different intermediates for C-C coupling, which can achieve the effect of highly efficient catalysis of CO2 hydrogenation and high-selectivity preparation of ethanol. It can achieve 85% ethanol selectivity during the catalysis of CO2 hydrogenation, and has the advantages of high ethanol selectivity, simple preparation process, and low cost, which are significantly better than most types of catalysts published currently.

[0021] (2) The preparation conditions of the catalyst in the present invention are mild, the preparation process is simple, and the cost is low. It is a new method that can be used for large-scale production. Description of the Drawings

[0022] Figure 1 SEM images of catalyst a prepared in Comparative Example 3 and catalyst A prepared in Example 1.

[0023] Figure 2This is the TEM image of catalyst A prepared in Example 1.

[0024] Figure 3 The catalytic performance comparison chart of catalyst A prepared in Example 1 and catalysts F and G prepared in Comparative Examples 1 and 2 is shown.

[0025] Figure 4 The catalytic performance comparison chart of different catalysts prepared in Examples 1 to 5 and Comparative Examples 3 to 5 is shown.

[0026] Figure 5 The catalytic performance comparison chart of catalysts A, A1 and A2 prepared at different reduction temperatures in Example 1 and Examples 6 and 7 is shown.

[0027] Figure 6 XRD patterns of different catalysts prepared in Examples 1 to 5 and Comparative Examples 3 and 4.

[0028] Figure 7 This is the XPS O1s spectrum of the catalyst prepared in Examples 1 to 5.

[0029] Figure 8 In-situ infrared spectra of catalyst A prepared in Example 1 and catalysts a and b prepared in Comparative Examples 3 and 4. DETAILED DESCRIPTION

[0030] A highly dispersed supported CuNi alloy catalyst with rich surface hydroxyl groups, the preparation steps of which are as follows: 1) Fully dissolve the Cu salt, Ni salt and carrier metal salt in a solvent, add a spacer chelating agent, heat and stir at 25-300°C for 0.1-72 h to generate a mixed metal salt precipitate; 2) filtering, washing, and drying the mixed metal salt precipitate obtained in step 1) at 60-300° C. to obtain a mixed metal salt precursor; 3) The mixed metal salt precursor obtained in step 2) is reduced at 100-800° C. for 0.5-72 h in a H2 / N2 mixed gas atmosphere containing 1%-100% H2 to obtain a highly dispersed supported CuNi alloy catalyst with rich surface hydroxyl groups.

[0031] Among them, the Cu salt described in step 1) is nitrate, hydrochloride, sulfate and / or acetate of copper. The Ni salt is nitrate, hydrochloride, sulfate and / or acetate of nickel. The supported metal salt is nitrate, hydrochloride, sulfate and / or acetate of one or more of Zr, Al, and Ti. The spacer chelating agent is one or more of urea, thiourea, and carbonyldiimidazole. The solvent is deionized water or a mixture of it and one or more of methanol, ethanol, and acetonitrile, where the volume ratio of deionized water is 10 - 100%. The dosage of the metal salt relative to the solvent is 0.01 - 50 mol / L, where Cu accounts for 0 - 60% of the total metal molar amount, and Ni accounts for 0 - 60% of the total metal molar amount. The dosage of the spacer chelating agent relative to the solvent is 0.01 - 50 mol / L.

[0032] To make the content of the present invention easier to understand, the technical solutions of the present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited thereto.

[0033] Example 1 1) Dissolve 15 mmol of copper nitrate, 15 mmol of nickel nitrate, and 10 mmol of zirconium nitrate in 200 mL of deionized water, place it in an oil bath, heat it at 105 °C and stir vigorously to mix. After the solution becomes clear, add 300 mmol of urea and continue to react for 8 h. After the reaction, filter to separate the solid, wash it three times with deionized water, and then dry it in an oven at 80 °C for 24 h to obtain the catalyst precursor.

[0034] 2) Grind the dried catalyst precursor into powder, place it in a tubular furnace, and reduce it under a hydrogen atmosphere at 400 °C for 3 h to obtain the CuNi alloy catalyst A (Cu3Ni3Zr2).

[0035] Example 2 In step 1), change the dosage of copper nitrate to 25 mmol and the dosage of nickel nitrate to 5 mmol, and the remaining steps are the same as in Example 1 to obtain the CuNi alloy catalyst B (Cu5Ni1Zr2).

[0036] Example 3 In step 1), change the dosage of copper nitrate to 20 mmol and the dosage of nickel nitrate to 10 mmol, and the remaining steps are the same as in Example 1 to obtain the CuNi alloy catalyst C (Cu4Ni2Zr2).

[0037] Example 4 In step 1), change the dosage of copper nitrate to 10 mmol and the dosage of nickel nitrate to 20 mmol, and the remaining steps are the same as in Example 1 to obtain the CuNi alloy catalyst D (Cu2Ni4Zr2).

[0038] Example 5 In step 1), the dosage of copper nitrate was changed to 2.5 mmol, and the dosage of nickel nitrate was changed to 27.5 mmol. The remaining steps were the same as in Example 1, and the CuNi alloy catalyst E (Cu 0.5 Ni 5.5 Zr2) was obtained.

[0039] Example 6 The reduction temperature in step 2) was changed to 350 °C, and the remaining steps were the same as in Example 1, obtaining the CuNi alloy catalyst A1 reduced at 350 °C.

[0040] Example 7 The reduction temperature in step 2) was changed to 450 °C, and the remaining steps were the same as in Example 1, obtaining the CuNi alloy catalyst A2 reduced at 450 °C.

[0041] Comparative Example 1 The catalyst precursor obtained in step 1) was first placed in a muffle furnace and calcined at 400 °C for 4 h, and then reduced in a tubular furnace at 400 °C under a hydrogen atmosphere for 3 h according to step 2), obtaining the catalyst F (Cu3Ni3Zr2 - calcined).

[0042] Comparative Example 2 1) Dissolve 15 mmol of copper nitrate, 15 mmol of nickel nitrate, and 10 mmol of zirconium nitrate in 100 mL of deionized water, place it in an oil bath, heat it at 105 °C and stir vigorously to mix. After the solution becomes clear, slowly add 100 ml of a mixed solution containing 0.3 mol / L NaOH and 0.1 mol / L Na2CO3 and continue to react for 8 h. After the reaction ends, filter to separate the solid, wash it three times with deionized water, and then place it in an 80 °C oven to dry for 24 h to obtain the catalyst precursor.

[0043] 2) Grind the dried catalyst precursor into powder, place it in a muffle furnace, calcine it at 400 °C for 4 h, and then reduce it in a tubular furnace at 400 °C under a hydrogen atmosphere for 3 h according to step 2), obtaining the catalyst G (Cu3Ni3Zr2 - alkali).

[0044] Comparative Example 3 1) Dissolve 15 mmol of copper nitrate and 10 mmol of zirconium nitrate in 200 mL of deionized water, place it in an oil bath, heat it at 105 °C and stir vigorously to mix. After the solution becomes clear, add 300 mmol of urea and continue to react for 8 h. After the reaction ends, filter to separate the solid, wash it three times with deionized water, and then place it in an 80 °C oven to dry for 24 h to obtain the catalyst precursor.

[0045] 2) Grind the dried catalyst precursor into powder, place it in a tubular furnace, and reduce it at 400 °C under a hydrogen atmosphere for 3 h to obtain catalyst a (Cu3Zr2).

[0046] Comparative Example 4 Change copper nitrate in step 1) to an equimolar amount of nickel nitrate, and the remaining steps are the same as in Comparative Example 3 to obtain catalyst b (Ni3Zr2).

[0047] Comparative Example 5 Change zirconium nitrate in step 1) to 15 mmol of nickel nitrate, and the remaining steps are the same as in Comparative Example 3 to obtain catalyst c (Cu3Ni3).

[0048] To observe the morphological structure of the catalyst, SEM characterization was performed on catalyst a prepared in Comparative Example 3 and catalyst A prepared in Example 1. The results are shown in Figure 1 . It can be seen from Figure 1 that there are a large number of agglomerated Cu particles in catalyst a, while no obvious Cu agglomeration phenomenon is observed in the CuNi alloy catalyst A, indicating that the active metals Cu and Ni in the CuNi alloy prepared in the present invention have good dispersion.

[0049] To further observe the morphological structure of the catalyst, TEM characterization was performed on catalyst A prepared in Example 1. The results are shown in Figure 2 . It can be clearly observed from Figure 2 the 111 and 200 crystal planes belonging to the CuNi alloy, verifying the existence of the CuNi alloy. The 111 and 200 crystal planes belonging to ZrO2 can also be observed. In addition, some cross-grid lattice fringes can be observed, which are attributed to the overlapping region of the CuNi alloy and ZrO2 phases, indicating that the CuNi alloy is supported on the ZrO2 substrate.

[0050] Application Example The prepared catalyst was tested for CO2 hydrogenation performance in a batch autoclave reactor. 50 mg of the catalyst was added to the reactor, 5 ml of 1,4-dioxane was used as the reaction solvent, and a CO2 / H2 / Ar mixed gas with a CO2 and H2 ratio of 1:3 was charged to 4 MPa. The reaction temperature was 200 °C, and the reaction time was 8 h.

[0051] Figure 3It is a comparison chart of the catalytic performances of catalysts A, F, and G. As can be seen from the figure, catalyst A prepared by the direct reduction method obviously has a higher CO2 conversion rate than catalyst F prepared by calcination followed by reduction, indicating that the direct reduction method helps to retain the surface hydroxyl groups capable of activating CO2. For catalyst G prepared with an alkali solution as an intercalating chelating agent, the catalytic product is mainly methane, probably because the process of precipitating metals with the alkali solution is rapid, resulting in insufficient dispersion of the active metals. Larger metal particles are formed after calcination and reduction, thus having a high selectivity for methane. This proves that the catalyst prepared with urea as an intercalating chelating agent and by the direct reduction method has more excellent performance.

[0052] Figure 4 It is a comparison chart of the catalytic performances of catalysts A - E and catalysts a - c. It can be clearly seen from the figure that the catalytic performance of the CuNi alloy catalyst A is significantly better than that of the single - metal catalysts a and b. And with the increase of the Ni loading amount, the methane selectivity continuously rises. Among them, catalyst A with a CuNi ratio of 1:1 has better catalytic performance. Its ethanol selectivity can reach 85% in the total alcohols, and the CO2 conversion rate can reach 14%. This catalytic performance is better than that of the vast majority of non - noble metal catalysts reported currently.

[0053] Figure 5 It is a comparison chart of the catalytic performances of catalysts A, A1, and A2 prepared at different reduction temperatures. As can be seen from the figure, with the increase of the reduction temperature, the CO2 conversion rate shows an upward trend, but at the same time, the methane selectivity also increases. Catalyst A with a reduction temperature of 400 °C has both a relatively high CO2 conversion rate and ethanol selectivity.

[0054] To deeply study the structure - activity relationship of the catalyst, XRD characterization was carried out, and the results are as Figure 6 shown (in the figure, the Cu loading amount gradually increases from bottom to top. The single - metal catalysts a and b in the comparative examples are at the bottom and top respectively, and the middle are CuNi alloy catalysts A, B, C, D, and E with different ratios). It can be observed from the figure that the 111, 200, and 220 crystal planes belonging to Cu and Ni show regular offsets from bottom to top. The offset phenomenon can be observed more clearly from the enlarged view in the right - hand area. The regular offset of the crystal plane peaks also verifies the formation of the CuNi alloy. At the same time, the 111, 200, and 211 crystal plane peaks belonging to ZrO2 are also observed, indicating that ZrO2 in the catalyst has a good crystal structure after reduction. In addition, the 111 crystal plane peak belonging to Cu2O is observed for some catalysts, indicating that Cu in the catalyst may exist in the form of a mixed valence state.

[0055] XPS characterization was further carried out, and the results are as Figure 7 shown. From Figure 7From the O 1s spectrum, we can see that each catalyst has a certain amount of surface hydroxyl groups, among which catalyst A has the highest surface hydroxyl content of 13.7%. Combined with its optimal catalytic performance, it is speculated that surface hydroxyl groups may play an important role in the process of CO2 hydrogenation to ethanol.

[0056] In situ infrared characterization was performed on the catalyst A with better performance and the single metal catalysts a and b for comparison to explore the reaction mechanism of catalytic CO2 hydrogenation to ethanol. The results are as follows: Figure 8 As shown. Figure 8 It can be seen that the peaks of intermediates generated after CO2 adsorption activation, such as CO3*, HCO3*, and HCOO3*, can be observed in the in-situ infrared spectra of the three catalysts. It is worth noting that in the spectrum of catalyst A, an obvious C2H5O* intermediate peak belonging to ethanol generation can be observed, while this peak of the other two comparison catalysts is very weak. In addition, at 2016 cm -1 A large peak at 2080 cm-1 belonging to bridging CO can be observed, which is not observed in the other two comparative catalysts. -1 The peak of gaseous CO at 1461 cm -1 The CH3* peak at 3016 cm-1 indicates that the formation of ethanol is likely to be achieved through the key step of carbon-carbon coupling between bridging CO and CH3*. -1 A peak belonging to the production of CH4 gas was observed at , and Ni is recognized as a metal with strong hydrogenation ability, indicating that metal Ni is the active center for the production of methane, so its content in the alloy catalyst needs to be controlled.

[0057] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A preparation method of a highly dispersed supported CuNi alloy catalyst with a surface rich in hydroxyl groups, characterized in that, Using Cu salts and Ni salts as active metal sources, under the action of water, the "spacer anchoring" and "selective adsorption" mechanisms of the spacer chelating agent are utilized to achieve the construction of adjacent Cu and Ni species. Through the competitive mechanism of "chelating action" and "precipitation action" generated by the spacer chelating agent and its hydrolysis, the adjacent Cu and Ni species are slowly and orderly dispersed and grown on the surface of the supported metal, and then an orderly and controllable mixed metal salt precipitate is formed. After filtration, washing, and drying, a mixed metal salt precursor is obtained. Then, the precursor is directly reduced to selectively reduce the active metal, and the spacer chelating agent is used to in-situ remove organic small molecules and generate active surface hydroxyl groups at the same time, thereby obtaining the highly dispersed supported CuNi alloy catalyst with a hydroxyl-rich surface.

2. The preparation method of a highly dispersed supported CuNi alloy catalyst with a surface rich in hydroxyl groups according to claim 1, characterized in that, It includes the following steps: 1) Fully dissolve Cu salts, Ni salts, and supported metal salts in a solvent, and add a spacer chelating agent, and generate a mixed metal salt precipitate by heating and stirring; 2) Filter, wash, and dry the mixed metal salt precipitate obtained in step 1) to obtain a mixed metal salt precursor; 3) Perform high-temperature reduction on the mixed metal salt precursor obtained in step 2) to obtain a highly dispersed supported CuNi alloy catalyst with a hydroxyl-rich surface.

3. The preparation method of a highly dispersed supported CuNi alloy catalyst with a hydroxyl-rich surface according to claim 2, characterized in that, The Cu salt is nitrate, hydrochloride, sulfate, and / or acetate of copper; The Ni salt is nitrate, hydrochloride, sulfate, and / or acetate of nickel; The supported metal salt is nitrate, hydrochloride, sulfate, and / or acetate of one or more of Zr, Al, and Ti; The spacer chelating agent is an electron-rich organic compound containing heteroatoms, specifically one or more of urea, thiourea, and carbonyldiimidazole.

4. The preparation method of a highly dispersed supported CuNi alloy catalyst with a surface rich in hydroxyl groups according to claim 2, characterized in that, In step 1), the solvent is deionized water or a mixture of deionized water and one or more of methanol, ethanol, and acetonitrile, and the volume ratio of deionized water is 10 - 100%.

5. The preparation method of a highly dispersed supported CuNi alloy catalyst with a surface rich in hydroxyl groups according to claim 2, characterized in that, In step 1), the dosage of the metal salt relative to the solvent is 0.01 - 50 mol / L, where Cu accounts for 0 - 60% of the total metal molar amount, and Ni accounts for 0 - 60% of the total metal molar amount.

6. The preparation method of a highly dispersed supported CuNi alloy catalyst with a surface rich in hydroxyl groups according to claim 2, characterized in that, In step 1), the dosage of the spacer chelating agent relative to the solvent is 0.01 - 50 mol / L.

7. The preparation method of a highly dispersed supported CuNi alloy catalyst with a surface rich in hydroxyl groups according to claim 2, characterized in that, In step 1), the temperature of the heating and stirring is 25 - 300 °C, and the time is 0.1 - 72 h.

8. The preparation method of a highly dispersed supported CuNi alloy catalyst with a surface rich in hydroxyl groups according to claim 1, characterized in that, In step 3), the high-temperature reduction is carried out in a H₂ / N₂ mixed gas atmosphere containing 1% - 100% H₂ at 100 - 800 °C for 0.5 - 72 h.

9. A highly dispersed supported CuNi alloy catalyst with a hydroxyl-rich surface prepared by any of the methods as claimed in claims 1 - 8.

10. Use of a highly dispersed supported CuNi alloy catalyst with a hydroxyl-rich surface as claimed in claim 9 in the hydrogenation of CO₂ to ethanol.

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