Copper-based composite oxide catalyst and preparation method and application thereof

Abstract

The invention is suitable for the technical field of catalytic materials, and provides a copper-based composite oxide catalyst and a preparation method and application thereof. The catalyst is introduced through 1-16 times of atomic layer deposition by taking aluminum oxide as a carrier, copper as a core active metal component with the mass fraction of 3-15wt% and zirconium oxide as a synergistic active component. By means of the atomic layer deposition technology, the covering state of zirconium oxide on the surface of aluminum oxide loaded copper is precisely regulated and controlled, controllable evolution of the aluminum oxide loaded copper from high-dispersion nanoclusters to a continuous oxide film is achieved, and a copper-zirconium oxide interface of a uniform structure is constructed. A nanocluster interface under a low deposition cycle number can significantly improve the conversion rate of methanol prepared by CO2 hydrogenation and the space-time yield of methanol, and the performance is superior to that of a traditional liquid phase method catalyst; the zirconium oxide covering layer can effectively inhibit sintering and agglomeration of copper particles and prolong the service life of the catalyst; and the catalyst can realize excellent performance only with low copper loading capacity, and has performance advantages and cost benefits.

Description

Technical Field

[0001] This application belongs to the field of catalytic materials technology, and in particular relates to a copper-based composite oxide catalyst, its preparation method and application. Background Technology

[0002] Carbon dioxide (CO2), as one of the most significant greenhouse gases, has caused serious environmental and climate problems due to its massive emissions. Converting CO2 into high-value-added chemicals is a promising approach. Among these methods, the hydrogenation of CO2 to methanol is considered one of the most industrially promising CO2 conversion routes due to the high energy density, ease of storage and transportation, and wide range of downstream chemical applications of methanol.

[0003] Currently, the most widely used methanol synthesis catalyst system in industry is the Cu / ZnO / Al2O3 system, with a copper loading typically of 50-60 wt%. This catalyst has achieved large-scale application in syngas systems, but in hydrogenation systems where CO2 is the main carbon source, it suffers from low reactivity, poor methanol selectivity, and insufficient long-term stability. Studies have shown that introducing zirconium oxide into copper-based catalysts can significantly improve the performance of CO2 hydrogenation to methanol. Compared to zinc oxide, zirconium oxide has stronger adsorption and activation capabilities for CO2, and its oxide properties are more stable. The metal-oxide interface structure formed between copper and zirconium oxide is the core factor determining catalytic performance.

[0004] However, in existing technologies, zirconium oxide is mostly introduced through co-precipitation, impregnation, or sol-gel methods. These liquid-phase methods struggle to precisely control the nucleation and growth of zirconium species on the copper surface, easily leading to localized enrichment or particle agglomeration of zirconium species. This prevents the formation of a uniform and controllable copper-zirconia interface structure, limiting further improvements in catalyst performance. Therefore, there is an urgent need to develop a technique capable of precisely controlling the dispersion and coverage of zirconium oxide on the copper surface at the nanoscale to construct a uniform copper-zirconia interface, meeting the requirements for efficient and stable CO2 hydrogenation to methanol reactions. Summary of the Invention

[0005] The purpose of this application is to provide a copper-based composite oxide catalyst, which aims to solve the problems of insufficient activity, selectivity and stability of existing copper-based catalysts in the CO2 hydrogenation to methanol reaction.

[0006] The embodiments of this application are implemented as follows: a copper-based composite oxide catalyst is composed of a support, a core active metal component, and synergistic active components; wherein,

[0007] The support is alumina; the core active metal component is copper, which is loaded on the surface of the support and has a mass fraction of 3-15 wt%; the synergistic active component is zirconium oxide, which together with copper constitutes the active sites of the catalyst. The zirconium oxide is introduced by atomic layer deposition, with a corresponding atomic layer deposition cycle number of 1-16 times and a mass fraction of 5-25 wt%.

[0008] Another objective of this application is a method for preparing the above-mentioned copper-based composite oxide catalyst, comprising:

[0009] Step S1: The copper precursor is loaded onto the alumina support using the equal volume impregnation method, and the mass fraction of copper is controlled to be 3-15 wt%. After drying and calcination, the Cu / Al2O3 precursor is obtained.

[0010] Step S2: The Cu / Al2O3 precursor is placed in an atomic layer deposition reactor, and ZrO2 atomic layer deposition reaction is carried out for 1-16 cycles using zirconium precursor and oxidant as reaction source to deposit ZrO2 nanoclusters on the surface of Cu / Al2O3 precursor.

[0011] Step S3: The product after atomic layer deposition is subjected to calcination and reduction treatment in sequence to obtain the copper-based composite oxide catalyst.

[0012] Another objective of this application is to apply the above-mentioned copper-based composite oxide catalyst to a fixed-bed reactor for the reaction of CO2 hydrogenation to methanol; the reactants are CO2 and H2 in a volume ratio of 1:3; the reaction temperature is 200-300℃ and the reaction pressure is 3-6 MPa.

[0013] The copper-based composite oxide catalyst provided in this application utilizes atomic layer deposition (ALD) technology to control the coverage state of zirconium oxide on the copper surface, achieving a controllable evolution from nanoclusters to continuous thin films. This constructs a uniform copper-zirconia interface. The nanocluster interface formed under low deposition cycle numbers can significantly improve CO2 conversion and methanol space-time yield, exhibiting superior performance compared to catalysts prepared by traditional liquid-phase methods. Simultaneously, the zirconium oxide coating effectively inhibits the sintering and agglomeration of copper particles, greatly extending the catalyst's lifespan. Furthermore, this catalyst requires only a low copper loading of 3-15 wt% to achieve excellent catalytic performance, combining performance advantages with cost-effectiveness. Attached Figure Description

[0014] Figure 1 This is a comparison diagram of the exposed surface area of ​​the catalyst Cu provided in Examples 1-6 and Comparative Example 1 of this application;

[0015] Figure 2High-resolution transmission electron microscopy (HRTEM) images of the catalysts provided in Examples 3(a), 5(b), and 6(c) of this application;

[0016] Figure 3 Transmission electron microscopy (TEM) elemental mapping of the catalysts provided in Example 3(a) and Comparative Example 1(b) of this application;

[0017] Figure 4 This is a comparison chart of the stability tests of the catalysts provided in Examples 1 and 3 of this application. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0019] This application provides a copper-based composite oxide catalyst, comprising a support, a core active metal component, and a synergistic active component. Alumina is selected as the support to provide a stable loading substrate for the active component. The core active metal component is copper, which is loaded onto the surface of the alumina support using an equal-volume impregnation method, with a copper mass fraction of 3-15 wt%, preferably 3-10 wt%. The synergistic active component is zirconium oxide, which, together with copper, constitutes the active sites of the catalyst. This zirconium oxide is introduced via atomic layer deposition (ALD), with a corresponding ALD cycle number of 1-16 times, preferably 2-8 times. By controlling the ALD cycle number, the zirconium oxide on the copper surface can be controllably evolved from nanoclusters to a continuous thin film.

[0020] This application also provides a method for preparing the above-mentioned copper-based composite oxide catalyst, including three core steps: Cu / Al2O3 precursor preparation, zirconium oxide atomic layer deposition, and calcination and reduction treatment, as detailed below:

[0021] Step S1: The copper precursor is loaded onto the alumina support using the equal volume impregnation method, and the mass fraction of copper is controlled to be 3-15 wt%. After drying and calcination, the Cu / Al2O3 precursor is obtained.

[0022] Step S2: The Cu / Al2O3 precursor is placed in an atomic layer deposition reactor, and ZrO2 atomic layer deposition reaction is carried out for 1-16 cycles using zirconium precursor and oxidant as reaction source to deposit ZrO2 nanoclusters on the surface of Cu / Al2O3 precursor.

[0023] Step S3: The product after atomic layer deposition is subjected to calcination and reduction treatment in sequence to obtain the copper-based composite oxide catalyst.

[0024] Optionally, step S1 includes: selecting a soluble copper salt as a copper precursor, dissolving it in deionized water to prepare an impregnation solution with a pore volume matching that of the alumina support; adding the alumina support to the impregnation solution and stirring thoroughly to impregnate it, so that the copper precursor is uniformly loaded on the support surface, controlling the copper mass fraction to be 3-15 wt%; after impregnation, drying the sample at 60-120℃ for 6-24 h, and then calcining it in air at 200-400℃ for 2-6 h, with a calcination heating rate of 1-10℃ / min. -1 The Cu / Al2O3 precursor was obtained.

[0025] To improve the dispersibility and crystallinity of copper species in the precursor, those skilled in the art can select the following preferred process conditions: the soluble copper salt is preferably copper nitrate, copper acetate, or copper chloride; the drying condition is preferably drying at 80°C for 12 h; the calcination condition is preferably calcination at 5°C for 1 minute. -1 The temperature was increased to 300°C at a heating rate and then calcined in air for 2 hours.

[0026] Optionally, step S2 includes: placing the Cu / Al2O3 precursor in an atomic layer deposition reactor, introducing an inert gas for atmosphere protection, controlling the reaction chamber temperature to 150-250°C, and sequentially pulse-introducing the zirconium precursor and oxidant; each deposition cycle includes four steps: zirconium precursor pulse, inert gas purging, oxidant pulse, and inert gas purging again; by controlling the number of deposition cycles from 1 to 16, ZrO2 species with controllable distribution are deposited on the surface of the Cu / Al2O3 precursor.

[0027] Preferably, the inert gas in step S2 is nitrogen; the zirconium precursor is tetra(dimethylamino)zirconium, zirconium chloride, or an alkoxyzirconium compound; the oxidant is water vapor, ozone, or oxygen; the deposition reaction temperature is preferably 200°C; and the preferred time parameters for each step in a single deposition cycle are: zirconium precursor pulse time 300s, inert gas purging time 300s, oxidant pulse time 600s, and re-purging time 300s.

[0028] Optionally, step S3 includes: placing the product after atomic layer deposition in a calcination apparatus and calcining it at 1-10°C for 1 minute under an air or oxygen atmosphere. -1 The temperature was increased to 350-500℃ at a rising rate, and then calcined at a constant temperature for 1-5 h to completely convert the deposited zirconium precursor into well-defined ZrO2. The calcined product was then transferred to a reduction apparatus, where hydrogen or a hydrogen-containing mixture was introduced, and the product was reduced at a constant temperature of 250-400℃ for 1-6 h, with the gas flow rate controlled at 30-200 mL / min during the reduction process. -1 Copper-based composite oxide catalysts can be prepared in this way.

[0029] Preferably, to further improve the conversion efficiency of ZrO2 and the dispersibility of Cu species, step S3 can adopt the following process conditions: the preferred calcination conditions are calcination at 400℃ for 2 h, with a heating rate of 5℃ / min. -1 The preferred reduction conditions are 300℃ for 2 h, with the reducing atmosphere gas flow rate controlled at 30 mL / min. -1 .

[0030] The copper-based composite oxide catalyst described in this application is suitable for the CO2 hydrogenation to methanol reaction in a fixed-bed reactor. Specific application conditions are as follows: the reactants are CO2 and H2 in a volume ratio of 1:3; the reaction temperature is controlled at 200-300℃, and the reaction pressure is controlled at 3-6 MPa. The total space velocity can be flexibly adjusted according to the reactor size and process requirements. Under these conditions, the catalyst can efficiently catalyze the hydrogenation of CO2 to methanol, while zirconium oxide can effectively inhibit the sintering and agglomeration of copper particles, ensuring stable performance of the catalyst during long-term continuous operation.

[0031] The following detailed embodiments illustrate the copper-based composite oxide catalyst, its preparation method, and its application provided in this application. Unless otherwise specified, the experimental methods used in the embodiments are conventional methods; and the materials and reagents used, unless otherwise specified, are commercially available conventional products.

[0032] Example 1: Preparation of Cu / Al2O3 precursor (Cu loading 5wt%)

[0033] Copper nitrate was selected as the copper precursor. Based on the pore volume parameters of the alumina support, copper nitrate was dissolved in deionized water to prepare an impregnation solution with a volume that perfectly matched the pore volume of the support. The alumina support was added to the impregnation solution and stirred thoroughly at room temperature to ensure that the copper precursor was uniformly adsorbed onto the support surface, with the copper mass fraction controlled at 5 wt%.

[0034] After impregnation, the sample was transferred to a forced-air drying oven and dried at 80°C for 12 h to remove free moisture from the system. The dried sample was then placed in a muffle furnace and dried at 5°C for 1 minute. -1 The heating rate was increased to 300℃, and the mixture was calcined at a constant temperature in air for 2 h to completely decompose copper nitrate into copper oxide, thus obtaining the Cu / Al2O3 precursor.

[0035] Example 2: Preparation of Cu / Al2O3@1ZrO2 catalyst (1 ALD cycle, Zr loading 5%)

[0036] The Cu / Al₂O₃ precursor obtained in Example 1 was placed in the ALD reaction chamber, and nitrogen gas was introduced as a protective gas at a flow rate of 10 mL / min. -1 Purge the chamber for 30 minutes to remove air and moisture. Heat the chamber to 200°C and maintain the temperature for 30 minutes.

[0037] Using tetra(dimethylamino)zirconium as the zirconium precursor and water vapor as the oxidant, a ZrO2 atomic layer deposition reaction was carried out in one cycle. The steps and duration of a single deposition cycle are as follows: zirconium precursor pulse 300 s → nitrogen purging 300 s → oxidant pulse 600 s → nitrogen purging again 300 s.

[0038] After deposition, the sample is removed and placed in a muffle furnace at 5°C for 1 minute. -1 The heating rate was increased to 400℃, and the sample was calcined in air for 2 h to completely convert the deposited zirconium precursor into ZrO2. The sample was then transferred to a fixed-bed reactor, and a 10 vol% H2 / Ar mixture was introduced at a flow rate of 30 mL / min. -1 , at 5℃min -1 The heating rate was increased to 300℃, and the reduction was carried out at a constant temperature for 2 h to obtain the Cu / Al2O3@1ZrO2 catalyst.

[0039] Example 3: Preparation of Cu / Al2O3 catalyst (2 ALD cycles, Zr loading 8%)

[0040] All the steps of Example 2 were repeated, except that the number of ZrO2 atomic layer deposition cycles was adjusted to 2, while all other process parameters (deposition temperature, carrier gas flow rate, duration of each step in a single cycle, calcination and reduction conditions) remained the same, to obtain a Cu / Al2O3@2ZrO2 catalyst. In this catalyst, ZrO2 is distributed on the Cu surface in the form of highly dispersed nanoclusters, without forming a continuous capping layer.

[0041] Example 4: Preparation of Cu / Al2O3@4ZrO2 catalyst (4 ALD cycles)

[0042] Repeat all the steps of Example 2, only adjusting the number of ZrO2 atomic layer deposition cycles to 4, while keeping all other process parameters the same, to obtain Cu / Al2O3@4ZrO2 catalyst (Zr loading 12%).

[0043] Example 5: Preparation of Cu / Al2O3@8ZrO2 catalyst (8 ALD cycles, Zr loading 18%)

[0044] All the steps of Example 2 were repeated, except that the number of ZrO2 atomic layer deposition cycles was adjusted to 8, while all other process parameters remained the same, to obtain a Cu / Al2O3@8ZrO2 catalyst. In this catalyst, ZrO2 is grown and bonded on the Cu surface to form a continuous oxide film with a thickness of approximately 1 nm.

[0045] Example 6: Preparation of Cu / Al2O3@16ZrO2 catalyst (16 ALD cycles, Zr loading 25%)

[0046] All the steps of Example 2 were repeated, except that the number of ZrO2 atomic layer deposition cycles was adjusted to 16, while all other process parameters remained the same, to obtain a Cu / Al2O3@16ZrO2 catalyst. The thickness of the continuous ZrO2 film in this catalyst was further increased to approximately 2 nm.

[0047] Examples 7-9: Preparation of copper-zirconia composite catalysts with different Cu loadings

[0048] Example 7: 3Cu / Al2O3@2ZrO2 catalyst (Cu loading 3 wt%)

[0049] The amount of copper nitrate was adjusted, and a Cu / Al2O3 precursor with a Cu mass fraction of 3wt% was prepared according to the method of Example 1. Then, the precursor was taken and ZrO2 atomic layer deposition, calcination and reduction were performed according to the process parameters of Example 3 (2 ALD cycles, Zr loading of 8%) to obtain 3Cu / Al2O3@2ZrO2 catalyst.

[0050] Example 8: 10Cu / Al2O3@2ZrO2 catalyst (Cu loading 10 wt%)

[0051] The amount of copper nitrate was adjusted, and a Cu / Al2O3 precursor with a Cu mass fraction of 10 wt% was prepared according to the method of Example 1. Then, the precursor was taken and ZrO2 atomic layer deposition, calcination and reduction were performed according to the process parameters of Example 3 (2 ALD cycles, Zr loading of 8%) to obtain 10Cu / Al2O3@2ZrO2 catalyst.

[0052] Example 9: 15Cu / Al2O3@2ZrO2 catalyst (Cu loading 15 wt%)

[0053] The amount of copper nitrate was adjusted, and a CuO / Al2O3 precursor with a Cu mass fraction of 15 wt% was prepared according to the method of Example 1. Then, the precursor was taken and ZrO2 atomic layer deposition, calcination and reduction were performed according to the process parameters of Example 3 (2 ALD cycles, Zr loading of 8%) to obtain 15Cu / Al2O3@2ZrO2 catalyst.

[0054] Comparative Example 1: Preparation of Cu / Al2O3@ZrO2 catalyst by liquid phase impregnation

[0055] To compare with the technical solution of this application, the catalyst was prepared by the traditional liquid phase impregnation method, and the Zr content was controlled to be comparable to that of the Cu / Al2O3@2ZrO2 catalyst in Example 3.

[0056] Zirconium chloride was selected as the zirconium precursor and dissolved in anhydrous ethanol to prepare a zirconium impregnation solution. The Cu / Al₂O₃ precursor obtained in Example 1 was added to the above impregnation solution, and the mixture was stirred and impregnated at room temperature for 1 h. Oxalic acid was added to the system as a precipitant, and the reaction was continued with stirring for 30 min to promote the deposition of Zr species on the catalyst surface. After the reaction, the mixture was transferred to a centrifuge and centrifuged at 8000 r / min for 10 min to collect the solid product. The solid product was washed three times with deionized water until the washing solution was neutral. The washed sample was placed in a forced-air drying oven and dried at 80 °C for 12 h. Subsequently, it was dried in a muffle furnace at 5 °C for 1 min. -1 The heating rate was increased to 400℃, and the sample was calcined in air for 2 hours. The calcined sample was then transferred to a fixed-bed reactor, and a hydrogen atmosphere was introduced. The temperature was increased at 5℃ / min. -1 The heating rate was increased to 300℃, and the reduction was carried out at a constant temperature for 2 h to obtain the liquid-phase Cu / Al2O3@ZrO2 catalyst (Zr loading 8%).

[0057] First, the exposed Cu surface area of ​​the catalysts prepared in Examples 1-6 and Comparative Example 1 was tested using the N2O titration method to investigate the influence of the ZrO2 deposition cycle number and preparation method on the degree of Cu surface exposure. The test results are as follows: Figure 1 As shown in the figure, the data indicates that the exposed area of ​​the catalyst on the Cu surface gradually decreases with the increase of ZrO2 atomic layer deposition cycles. This suggests that the coverage of ZrO2 on the Cu surface increases with the number of deposition cycles, highlighting the precise controllability of atomic layer deposition technology over the Cu-ZrO2 interface coverage. Meanwhile, under similar Zr content conditions, the sample in Comparative Example 1, which introduced Zr using the liquid phase method, had a significantly smaller exposed area on the Cu surface than the sample prepared by atomic layer deposition. This result demonstrates that the traditional liquid phase method is more likely to cause non-uniform deposition of Zr species on the Cu surface, leading to over-coverage of the Cu active surface.

[0058] Furthermore, the catalysts prepared in Examples 3, 5, and 6 were characterized by high-resolution transmission electron microscopy (HRTEM) to clarify the morphological evolution of ZrO2 on the Cu surface under different ZrO2 atomic layer deposition cycles. The characterization results are as follows: Figure 2As shown, under lower deposition cycle numbers, such as 2 cycles, ZrO2 is mainly distributed in a highly dispersed state on the Cu surface, and no obvious ZrO2 lattice fringes are observed. When the deposition cycle number increases to 8, ZrO2 gradually connects and fuses on the Cu surface, forming a continuous oxide film with a thickness of about 1 nm. When the deposition cycle number is further increased to 16, the ZrO2 film thickness increases to about 2 nm. The above morphological evolution pattern intuitively demonstrates the precise controllability of atomic layer deposition technology over the ZrO2 growth process.

[0059] Furthermore, the catalysts prepared in Example 3 and Comparative Example 1 were characterized by transmission electron microscopy (TEM) to compare the distribution differences of Zr species introduced by atomic layer deposition and conventional liquid phase methods. The characterization results are as follows: Figure 3 As shown, in the sample prepared by atomic layer deposition (ALD), Zr species exhibit a uniform distribution in the Cu particles and their surrounding areas; while in the sample prepared by liquid phase deposition (LPD), the distribution of Zr species shows significant heterogeneity, with localized areas exhibiting significant Zr species enrichment. This result indicates a fundamental difference in the controllability of Zr species distribution between the two preparation methods, with ALD offering significantly superior controllability.

[0060] Furthermore, the catalysts obtained in Examples 1-9 and Comparative Example 1 were used to evaluate the performance of the fixed-bed reactor. The catalyst and quartz sand were thoroughly mixed and then packed into a fixed-bed reactor. The catalyst loading amount was 100 mg, and the quartz sand loading amount was 1 g. The quartz sand was used to dilute the catalyst and improve the heat transfer effect during the reaction process. After loading, the reactor was first activated at 300°C for 2 h under a hydrogen atmosphere, and then the reaction gas was switched to a mixture of H2 and CO2.

[0061] The reaction conditions were set as follows: the molar ratio of H2 to CO2 was 3:1, the reaction temperature was 240℃, the reaction pressure was 5 MPa, and the total space velocity was 9000 mL g. -1 h -1 After the reaction stabilized, samples were taken, and the products were qualitatively and quantitatively analyzed by gas chromatography. Based on this, the CO2 conversion rate, methanol selectivity, and methanol space-time yield (STY) were calculated. The specific performance data of different catalysts are shown in Table 1.

[0062] in, Figure 4The results of the CO2 hydrogenation to methanol stability tests on the catalysts prepared in Examples 1 and 3 are presented to compare the effect of ZrO2 introduction on the long-term performance of the catalysts. The test results show that the Cu / Al2O3 catalyst without ZrO2 (Example 1) experienced a 23% decrease in methanol space-time yield (STY) after 80 hours of continuous operation; while the catalyst with ZrO2 supported by atomic layer deposition (Example 3) showed only an 18% decrease in methanol STY after 400 hours of continuous operation. This data clearly demonstrates that the introduction of a ZrO2 capping layer can effectively improve the long-term stability of Cu-based catalysts in the CO2 hydrogenation to methanol reaction.

[0063] Table 1

[0064]

[0065] As shown in Table 1, the number of ZrO2 deposition cycles and the Cu loading significantly regulate the performance of the catalyst in the CO2 hydrogenation to methanol reaction. Compared with the Cu / Al2O3 catalyst without ZrO2 (Example 1), the Cu / Al2O3@xZrO2 series catalysts with ZrO2 introduced through atomic layer deposition (ALD) significantly improve both methanol selectivity and methanol space-time yield. Samples prepared under low to medium deposition cycle conditions, such as Examples 2 and 3, exhibit superior CO2 conversion and methanol space-time yield, with Example 3 (2 deposition cycles) showing the highest methanol space-time yield. This indicates that the Cu-ZrO2 interface structure constructed under these conditions best meets the requirements of the CO2 hydrogenation to methanol reaction.

[0066] As the number of ZrO2 deposition cycles further increased (Examples 4-6), although the methanol selectivity of the catalyst remained at a high level, the CO2 conversion rate and methanol space-time yield both showed a significant downward trend. This indicates that excessive ZrO2 coverage will obscure some Cu active sites, thereby restricting further improvement of catalytic performance.

[0067] Furthermore, the Cu loading also has a crucial impact on catalyst performance (Examples 7-9). When the Cu loading is 5 wt%, the methanol space-time yield of the catalyst reaches its peak; however, when the Cu loading is reduced to 3 wt%, or increased to 10 wt% or 15 wt%, the methanol space-time yield decreases to varying degrees. This phenomenon is most likely directly related to the change in the degree of dispersion of Cu species on the support surface.

[0068] In comparison, under similar Zr content conditions, the catalyst in Comparative Example 1, which introduced Zr using a liquid-phase method, exhibited significantly lower CO2 conversion and methanol space-time yield than the sample prepared by atomic layer deposition (ALD). This fully demonstrates that the Cu-ZrO2 interface constructed using ALD technology has significant advantages in structural uniformity and controllability, which is more conducive to the full realization of catalytic activity.

[0069] In summary, the embodiments of this application precisely control the dispersion state and coverage of ZrO2 on the surface of Cu / Al2O3 catalyst using atomic layer deposition (ALD) technology, effectively avoiding the problems of local enrichment or particle agglomeration of Zr species that are prone to occur in traditional liquid-phase methods. This enables the controllable evolution of ZrO2 from highly dispersed nanoclusters to continuous oxide films. The discontinuous Cu-ZrO2 interface formed under low deposition cycle numbers can introduce a large number of active interfaces while maintaining appropriate exposure of Cu metal sites, significantly improving the reactivity of CO2 hydrogenation to methanol and the methanol space-time yield. The catalyst with two ALD cycles exhibits the best performance, with a CO2 conversion rate of 13.2% and a methanol space-time yield of 0.249 g gCat. -1 h -1 The performance far surpasses that of catalysts without ZrO2 and catalysts prepared by the liquid phase method. At the same time, the ZrO2 capping layer can effectively inhibit the sintering and agglomeration of Cu particles during the reaction, greatly improving the long-term stability of the catalyst. Compared with the unmodified Cu / Al2O3 catalyst, which reduced the methanol space-time yield by 23% within 80 h, this copper-based composite oxide catalyst only reduced it by 18% within 400 h. Moreover, it can achieve excellent catalytic performance with a low Cu loading of 3-15 wt%, combining performance advantages and cost-effectiveness.

[0070] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A copper-based composite oxide catalyst, characterized by comprising: The catalyst is composed of a carrier, a core active metal component and a synergistic active component. The carrier is alumina, the core active metal component is copper, which is loaded on the surface of the carrier with a mass fraction of 3-15wt%, and the synergistic active component is zirconium oxide, which, together with copper, forms the active sites of the catalyst.

2. The copper-based composite oxide catalyst according to claim 1, characterized by, The mass fraction of copper is 3-10wt%, and the number of atomic layer deposition cycles is 2-8.

3. A process for the preparation of a copper-based composite oxide catalyst as claimed in claim 1, characterized in that, The method comprises the following steps: Step S1: loading copper precursor on alumina carrier by equal volume impregnation method, controlling the mass fraction of copper to be 3-15wt%, and drying and calcining to obtain Cu / Al2O3 precursor; Step S2: placing the Cu / Al2O3 precursor in an atomic layer deposition reactor, using zirconium precursor and oxidant as reaction sources, and performing 1-16 cycles of ZrO2 atomic layer deposition reaction to deposit ZrO2 nanoclusters on the surface of the Cu / Al2O3 precursor; Step S3: sequentially performing calcination and reduction treatment on the product after atomic layer deposition to obtain the copper-based composite oxide catalyst.

4. The method of claim 3, wherein the copper-based composite oxide catalyst is prepared by the steps of: The step S1 comprises: The soluble copper salt is selected as a copper precursor, dissolved in deionized water to prepare an impregnation solution matching the pore volume of the alumina carrier; the alumina carrier is added into the impregnation solution for sufficient stirring and impregnation, the mass fraction of copper is controlled to be 3-15 wt%, then dried at 60-120℃ for 6-24 h, and calcined at 200-400℃ for 2-6 h in an air atmosphere, the heating rate is 1-10℃ / min -1 , to obtain a Cu / Al2O3 precursor.

5. The method of claim 4, wherein the copper-based composite oxide catalyst is prepared by the steps of: The soluble copper salt in step S1 is copper nitrate, copper acetate or copper chloride; the drying conditions are preferably 80°C for 12 h; the calcination conditions are preferably 300°C for 2 h, with a preferred ramp rate of 5°C min -1 .

6. The method for preparing the copper-based composite oxide catalyst according to claim 3, characterized in that, The step S2 comprises: Placing the Cu / Al2O3 precursor in an atomic layer deposition reactor under the protection of inert gas, controlling the reaction temperature to be 150-250℃, and sequentially introducing zirconium precursor and oxidant; each deposition cycle includes four steps of zirconium precursor pulse, inert gas purging, oxidant pulse and again inert gas purging, and 1-16 cycles of ZrO2 atomic layer deposition reaction are performed to deposit ZrO2 nanoclusters on the surface of the Cu / Al2O3 precursor.

7. The method for preparing the copper-based composite oxide catalyst according to claim 6, characterized in that, The zirconium precursor in step S2 is tetrakis (dimethylamino) zirconium, zirconium chloride or alkoxy zirconium compound; the oxidant is water vapor, ozone or oxygen; the deposition reaction temperature is preferably 200℃; the zirconium precursor pulse time of a single deposition cycle is 300s, the inert gas purging time is 300s, the oxidant pulse time is 600s, and the again purging time is 300s.

8. The method of making a copper-based composite oxide catalyst according to claim 3, wherein The step S3 comprises: The product after atomic layer deposition treatment is calcined in air or oxygen atmosphere at 350-500°C for 1-5 h, the temperature rising rate is 1-10°C / min -1 to make the deposition precursor completely transform into ZrO2; The roasted product is placed in a reduction device and reduced under a hydrogen or hydrogen-containing mixed gas atmosphere at 250-400°C for 1-6 h, with the gas flow rate controlled at 30-200 mL / min -1 to obtain a copper-based composite oxide catalyst.

9. The method of claim 8, wherein the copper-based composite oxide catalyst is prepared by the steps of: In step S3, the calcination conditions are preferably calcination at 400 °C for 2 h, with a ramp rate of 5 °C min -1 ; the reduction conditions are preferably reduction at 300 °C for 2 h, with a reduction atmosphere gas flow rate controlled at 30 mL min -1 .

10. Use of a copper-based composite oxide catalyst as claimed in claim 1, characterized in that, The catalyst is used in a fixed bed reactor for CO2 hydrogenation to methanol reaction; the reaction raw materials are CO2 and H2 with a volume ratio of 1:3; the reaction temperature is 200-300℃, and the reaction pressure is 3-6MPa.

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