A palladium-copper bimetallic base nanocatalyst, a preparation method and application thereof

Abstract

The present application relates to a kind of palladium copper bimetallic base nanometer catalyst and its preparation method and application, belong to metal-based catalyst technical field.The low carbon alcohol of the existing carbon dioxide conversion into high value-added technology is converted into carbon dioxide with low conversion rate, low carbon alcohol and the like problems such as low selectivity are solved.The palladium copper bimetallic base nanometer catalyst of the present application is prepared by step reduction method, first, the palladium precursor is reduced to palladium nanoparticles by reducing agent I, and is deposited on the oxide carrier, then the copper precursor is deposited on the surface of palladium nanoparticles by reducing agent II, finally, palladium copper bimetallic base nanometer catalyst is obtained.The preparation method has simple operation process, is easy to operate, has wide applicability, the catalyst prepared has high activity, good stability, high atom utilization rate, the catalyst is applied in carbon dioxide hydrogenation preparation low carbon alcohol reaction, the conversion rate of carbon dioxide is higher, the selectivity of low carbon alcohol is higher.

Description

Technical Field

[0001] This invention belongs to the field of metal-based catalyst technology, specifically relating to a palladium-copper bimetallic nanocatalyst, its preparation method and application, and particularly to the application of the palladium-copper bimetallic nanocatalyst in the hydrogenation of carbon dioxide to prepare lower alcohols. Background Technology

[0002] In recent years, the significant increase in atmospheric carbon dioxide concentration has posed a huge threat to the living environment of all mankind, and the reduction and utilization of carbon dioxide emissions has become an important global issue. As a cheap and renewable carbon and oxygen resource, converting carbon dioxide into high-value-added chemicals can not only alleviate the pressure of carbon dioxide emissions, but also realize the recycling of carbon resources. This is a fundamental way to achieve green chemistry and solve energy and environmental problems.

[0003] Current research on converting carbon dioxide into high-value-added chemicals mainly focuses on the hydrogenation of carbon dioxide to methanol. However, lower-carbon alcohols have higher energy density and higher market prices compared to methanol. Taking ethanol as an example, the current average market price of ethanol is 6500 yuan / ton, with a calorific value of 6350 kcal / kg, while the average market price of methanol is 2200 yuan / ton, with a calorific value of 4650 kcal / kg. Therefore, the preparation of lower-carbon alcohols (methanol, ethanol, propanol) through the hydrogenation of carbon dioxide further broadens the scope of carbon dioxide utilization, offering both economic and social benefits.

[0004] The key technology for the synthesis of lower alcohols from carbon dioxide via hydrogenation lies in the design and development of catalysts. Currently reported catalysts mainly include noble metal-based (palladium, rhodium, platinum, etc.), copper-based, molybdenum-based, and cobalt-based catalysts. Patent CN116899598A discloses a PdFe / Fe3O4 catalyst. This catalyst uses an iron salt solution as a precursor, prepares iron oxide via a sol-gel method or precipitation method, then loads it with noble metal palladium, and prepares it through high-temperature reduction. It is suitable for the synthesis of lower alcohols from carbon dioxide via hydrogenation. However, the reaction products are mainly alkanes and carbon monoxide. Patent CN103191747B discloses a method for preparing a CuZn / ZrO2 catalyst. This catalyst uses copper nitrate, zinc nitrate, and zirconium nitrate as precursors, and sodium carbonate as a precipitant, prepared via a co-precipitation method. It is suitable for the synthesis of lower alcohols from carbon dioxide via hydrogenation. However, the catalyst preparation process is complex and cumbersome, taking more than 50 hours. Patent CN201510369970 discloses a rhodium-based catalyst. This catalyst, in the presence of ruthenium complexes, rhodium complex catalysts, iodides, and solvents, hydrogenates carbon dioxide and hydrogen in a reactor to yield ethanol and higher alcohols. However, this catalyst is homogeneous and only suitable for batch reactions. Furthermore, its synthesis requires expensive organic ligands, and the air sensitivity of these ligands leads to poor catalyst stability. Bai et al. reported the preparation of a palladium-copper-based catalyst via a one-step reduction method, exhibiting ethanol selectivity in the hydrogenation of carbon dioxide; however, this catalyst is only suitable for batch reactions, limiting its industrial application prospects (J. Am. Chem. Soc. 2017, 139, 6827-6830).

[0005] In summary, existing catalysts for the hydrogenation of carbon dioxide to produce lower alcohols still suffer from drawbacks such as low carbon dioxide conversion rate, low selectivity of the product alcohols, poor catalyst stability, and complex preparation process. Summary of the Invention

[0006] This invention addresses the problems of low carbon dioxide conversion rate and low selectivity of low-carbon alcohols in existing technologies for converting carbon dioxide into high-value-added low-carbon alcohols. It provides a palladium-copper bimetallic nanocatalyst, its preparation method, and its application. The preparation method is simple, and the prepared catalyst exhibits good activity and stability. When applied to the reaction of carbon dioxide hydrogenation to produce low-carbon alcohols, the catalyst demonstrates a high carbon dioxide conversion rate and high selectivity for low-carbon alcohols.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] This invention provides a palladium-copper bimetallic nanocatalyst, comprising an oxide support, palladium nanoparticles deposited on the surface of the oxide support, and copper nanoparticles deposited on the surface of the palladium nanoparticles. The molar ratio of palladium to copper is 0.1 to 10, and the loading of palladium relative to the oxide support is 1 wt.% to 5 wt.%.

[0009] Preferably, the size of the palladium-copper bimetallic nanocatalyst is 6 nm to 20 nm.

[0010] Preferably, the oxide is one or more of silicon dioxide, aluminum oxide, titanium dioxide, zirconium oxide, and cerium oxide.

[0011] The present invention also provides a method for preparing the above-mentioned palladium-copper bimetallic nanocatalyst, the steps of which are as follows:

[0012] (1) Dissolve the palladium precursor and oxide support in solvent I, denoted as solution a; dissolve reducing agent I in deionized water, denoted as solution b;

[0013] The reducing agent I is one or more of sodium borohydride, potassium borohydride, and hydrazine hydrate. The molar ratio of reducing agent I to palladium is 10:1 to 2:1. The amount of oxide support is calculated as 1 wt.% to 5 wt.% of palladium relative to the oxide support.

[0014] (2) Add solution b dropwise to solution a and stir for several hours to form a precipitate;

[0015] (3) After centrifuging and washing the obtained precipitate, it is redispersed in solvent II and denoted as solution c;

[0016] (4) Dissolve the copper precursor in deionized water and denote it as solution d; mix solution d and solution c evenly to obtain a mixed solution; in the mixed solution, the molar ratio of copper to palladium is 1:10 to 1:2.

[0017] (5) Dissolve reducing agent II in deionized water and denote it as solution e; add solution e dropwise to the mixed solution and stir for several hours to form a precipitate;

[0018] The reducing agent II is one or more of ascorbic acid, aminoborane complex, diborane, and ethylene glycol, and the molar ratio of reducing agent II to copper is 10:1 to 2:1.

[0019] (6) The precipitate was centrifuged, washed, dried and ground into powder to obtain palladium-copper bimetallic nanocatalyst.

[0020] Preferably, in step (1), the palladium precursor is one or more of palladium acetate, palladium chloride, palladium nitrate, palladium acetylacetone, and potassium tetrachloropalladate.

[0021] Preferably, in step (1), solvent I is one or more of deionized water, acetone, methanol, ethanol, and ethylene glycol, and the concentration of palladium in solution a is 0.05 mol / L to 1 mol / L.

[0022] Preferably, in step (2), the stirring speed is 400 r / min to 1000 r / min, and the stirring time is 1 to 5 h.

[0023] Preferably, in step (3), the centrifugal washing method is: centrifugation washing with deionized water and anhydrous ethanol 1 to 3 times respectively.

[0024] Preferably, in step (3), solvent II is one or more of deionized water, acetone, methanol, ethanol, and ethylene glycol.

[0025] Preferably, in step (4), the copper precursor is one or more of copper nitrate, copper chloride, copper sulfate, copper acetylacetone, and copper acetate.

[0026] Preferably, in step (5), the stirring speed is 400 r / min to 1000 r / min, and the stirring time is 1 h to 5 h;

[0027] Preferably, in step (6), the washing method is: centrifugation washing with deionized water and anhydrous ethanol 1 to 5 times respectively.

[0028] Preferably, in step (6), the drying temperature is 60℃~150℃ and the drying time is 5h~24h.

[0029] The present invention also provides the application of the above-mentioned palladium-copper bimetallic nanocatalyst in the synthesis of lower alcohols by carbon dioxide hydrogenation.

[0030] Preferably, the lower alcohol is one or more of methanol, ethanol, and propanol.

[0031] Preferably, the steps are as follows:

[0032] (1) The palladium-copper bimetallic nanocatalyst was subjected to hydrogen pre-reduction treatment. The pre-reduction treatment conditions were: space velocity of 3000 mL / g / h~10000 mL / g / h, temperature of 200℃~400℃, and reduction time of 0.5h~5h.

[0033] (2) After the pre-reduction treated palladium-copper bimetallic nanocatalyst is pressed into tablets, crushed, and sieved to a particle size of 10-80 mesh, it is loaded into a fixed bed reactor and subjected to carbon dioxide hydrogenation reaction to obtain low carbon alcohol.

[0034] The reaction conditions are as follows: reaction temperature 200℃~400℃, reaction pressure 2MPa~4MPa, space velocity 3000mL / g / h~8000mL / g / h, and the gas used is a mixture of CO2 and H2 with a volume ratio of 1:1~1:5.

[0035] The principle of this invention is as follows:

[0036] The palladium-copper bimetallic nanocatalyst of the present invention is prepared by a stepwise reduction method, in which the types and concentrations of reducing agents used in the two reductions are different. The palladium precursor is reduced to palladium nanoparticles by reducing agent I and deposited on an oxide support. Then, the copper precursor is deposited on the surface of the palladium nanoparticles by reducing agent II, and finally the palladium-copper bimetallic nanocatalyst is obtained.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] (1) The preparation method of the palladium-copper bimetallic nanocatalyst of the present invention is simple, easy to operate, and has wide applicability.

[0039] (2) The palladium-copper bimetallic nanocatalyst of the present invention has high activity, good stability and high atom utilization. By adjusting the ratio of palladium and copper and changing the type of oxide support, different distributions of alcohol products can be obtained.

[0040] (3) This invention precisely controls the reduction rate of metal ions by adjusting the concentration and type of reducing agent, so that palladium and copper exist in the catalyst in a highly dispersed bimetallic form. This not only strengthens the interaction between synergistic palladium and copper metals, but also improves the metal-support interaction between the bimetallic component and the support, which is beneficial to the activation of carbon dioxide and the regulation of reaction intermediates, thereby improving the conversion rate of carbon dioxide and the selectivity of low-carbon alcohols, which is far superior to single palladium-based catalysts, copper-based catalysts, and palladium-copper catalysts prepared by direct one-step reduction. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 High-resolution transmission electron microscopy (HR-TEM) image of the palladium-copper bimetallic nanocatalyst prepared in Example 1 of this invention. Detailed Implementation

[0043] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to embodiments.

[0044] In the following embodiments, various processes and methods not described in detail are conventional methods known in the art. Unless otherwise specified, the materials, reagents, apparatus, instruments, equipment, etc., used in the following embodiments are commercially available.

[0045] Example 1

[0046] First, 2 g of silicon dioxide and 0.086 g of palladium nitrate were dissolved in 6 mL of deionized water and stirred until homogeneous to obtain a mixed solution. Excess sodium borohydride aqueous solution was added dropwise to the mixed solution, and the mixture was stirred for 1 h (stirring speed 400 r / min–1000 r / min) to form a precipitate, wherein the molar ratio of sodium borohydride to palladium nitrate was 10:1. The precipitate was washed twice by centrifugation with deionized water and anhydrous ethanol, respectively, and redispersed in deionized water. Copper nitrate aqueous solution was added and stirred until homogeneous to obtain a mixed solution, wherein the molar ratio of copper nitrate to palladium nitrate was 1:3. An aqueous solution of ammonia borane complex was added dropwise to the mixed solution, and the mixture was stirred for 2 h (stirring speed 400 r / min–1000 r / min) to form a precipitate, wherein the molar ratio of ammonia borane complex to copper nitrate was 5:1. The precipitate was washed three times by centrifugation with deionized water and anhydrous ethanol, respectively, and then dried at 60 °C for 12 h to obtain a palladium-copper bimetallic nanocatalyst.

[0047] The morphology and composition of the palladium-copper bimetallic nanocatalysts were observed using transmission electron microscopy (TEM) or high-resolution transmission electron microscopy (HRTEM). The results are as follows: Figure 1 As shown, upon observation, palladium and copper in the palladium-copper bimetallic nanocatalyst obtained in Example 1 exist in a bimetallic form, and the size of the palladium-copper bimetallic nanocatalyst is approximately 8 nm.

[0048] Example 2

[0049] Replace the molar ratio of copper nitrate to palladium nitrate in Example 1 with 1:8, and perform the other operations as in Example 1.

[0050] Example 3

[0051] The molar ratio of copper nitrate to palladium nitrate in Example 1 was replaced with 1:10, and other operations were the same as in Example 1.

[0052] Example 4

[0053] Replace the molar ratio of copper nitrate to palladium nitrate in Example 1 with 1:1, and perform the other operations as in Example 1.

[0054] Example 5

[0055] The palladium precursor in Example 1 was replaced with palladium acetylacetone, and other operations were the same as in Example 1.

[0056] Example 6

[0057] The copper precursor in Example 1 was replaced with copper acetate, and other operations were the same as in Example 1.

[0058] Example 7

[0059] In Example 1, the molar ratio of the ammonia borane complex to copper nitrate was changed to 10:1, and other operations were the same as in Example 1.

[0060] Example 8

[0061] The oxide carrier silica in Example 1 was replaced with alumina. Other operations were the same as in Example 1.

[0062] Example 9

[0063] The oxide carrier silicon dioxide in Example 1 was replaced with titanium dioxide. Other operations were the same as in Example 1.

[0064] Example 10

[0065] 2 g of silica and 0.086 g of palladium nitrate were dissolved in 6 mL of deionized water and stirred until homogeneous. Excess sodium borohydride aqueous solution was added dropwise to the mixture and stirred for 1 h (stirring speed 400 r / min–1000 r / min) to form a precipitate, wherein the molar ratio of sodium borohydride to palladium nitrate was 5:1. The precipitate was washed twice by centrifugation with deionized water and anhydrous ethanol, respectively, and redispersed in deionized water. Copper nitrate aqueous solution was added and stirred until homogeneous, obtaining a mixed solution with a molar ratio of copper nitrate to palladium nitrate of 1:3. Ascorbic acid aqueous solution was added dropwise to the mixed solution and stirred for 2 h (stirring speed 400 r / min–1000 r / min) to form a precipitate, wherein the molar ratio of ascorbic acid to copper nitrate was 2:1. The precipitate was washed three times by centrifugation with deionized water and anhydrous ethanol, respectively, and then dried at 60 °C for 12 h to obtain a palladium-copper bimetallic nanocatalyst.

[0066] Comparative Example 1

[0067] 2 g of silicon dioxide and 0.086 g of palladium nitrate were dissolved in 6 mL of deionized water and stirred until homogeneous to obtain a mixed solution. Excess sodium borohydride aqueous solution was added dropwise to the mixed solution, and the mixture was stirred for 1 h (stirring speed 400 r / min–1000 r / min) to form a precipitate, wherein the molar ratio of sodium borohydride to palladium nitrate was 10:1. The precipitate was washed twice by centrifugation with deionized water and anhydrous ethanol, respectively, and dried at 60 °C for 12 h to obtain the catalyst.

[0068] Comparative Example 2

[0069] 2 g of silicon dioxide and 0.12 g of copper nitrate were dissolved in 6 mL of deionized water and stirred until homogeneous to obtain a mixed solution. Excess sodium borohydride aqueous solution was added dropwise to the mixed solution, and the mixture was stirred for 1 h (stirring speed 400 r / min~1000 r / min) to form a precipitate, wherein the molar ratio of sodium borohydride to copper nitrate was 10:1. The precipitate was washed twice by centrifugation with deionized water and anhydrous ethanol, respectively, and dried at 60 °C for 12 h to obtain the catalyst.

[0070] Comparative Example 3

[0071] 2 g of silicon dioxide, 0.086 g of palladium nitrate, and 0.12 g of copper nitrate were dissolved in 6 mL of deionized water and stirred until homogeneous to obtain a mixed solution. Excess sodium borohydride aqueous solution was added dropwise to the mixed solution, and the mixture was stirred for 1 h (stirring speed 400 r / min–1000 r / min) to form a precipitate, wherein the molar ratio of sodium borohydride to the total of copper nitrate and palladium nitrate was 10:1. The precipitate was washed twice by centrifugation with deionized water and anhydrous ethanol, respectively, and dried at 60 °C for 12 h to obtain the catalyst.

[0072] Comparative Example 4

[0073] The reduction sequence in Example 1 was changed to first adding a copper precursor, then reducing it with an ammonia borane complex, and finally adding a palladium precursor and reducing it with sodium borohydride. Other operations were the same as in Example 1.

[0074] Comparative Example 5

[0075] The ammonia borane complex in Example 1 was replaced with sodium borohydride, and other operations were the same as in Example 1.

[0076] The reaction performance of the catalysts prepared in Examples 1-10 and Comparative Examples 1-5 was evaluated.

[0077] Before the reaction test, the catalyst was pre-reduced with hydrogen. The pre-reduction conditions were: space velocity of 8000 mL / g / h, pretreatment temperature of 300℃, and reduction for 2 h. After the temperature dropped to room temperature, the pre-reduced catalyst was tableted, pulverized, and sieved to a particle size of 10-80 mesh, and then loaded into a fixed-bed reactor for reaction performance evaluation. The reaction temperature was 270℃, the reaction pressure was 3 MPa, the space velocity was 6000 mL / g / h, and the gas used was a mixture of CO2 and H2 with a volume ratio of 1:1 to 1:5.

[0078] The reaction test results are shown in Table 1.

[0079] Table 1. Catalyst activity evaluation results

[0080]

[0081]

[0082] As shown in Table 1, the conversion rate of carbon dioxide and the selectivity of alcohols were relatively low when using catalysts prepared by one-step direct reduction or single palladium-based and copper-based catalysts. Furthermore, changing the reduction sequence also significantly affected the catalytic performance. The catalyst of this invention exhibited excellent catalytic performance in the catalytic hydrogenation of carbon dioxide to lower alcohols, with significantly improved catalytic activity and selectivity for lower alcohols. Simultaneously, by changing the molar ratio of palladium to copper, the type of support, and the type and concentration of the reducing agent, the product distribution of lower alcohols could be effectively controlled.

[0083] Obviously, the above embodiments are merely examples for clear illustration and are not intended to limit the embodiments. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all embodiments here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A palladium-copper bimetallic nanocatalyst, characterized in that, The catalyst comprises an oxide support, palladium nanoparticles deposited on the surface of the oxide support, and copper nanoparticles deposited on the surface of the palladium nanoparticles, wherein the molar ratio of palladium to copper is 0.1–10, and the loading of palladium relative to the oxide support is 1 wt.%–5 wt.%; the preparation method of the catalyst is as follows: (1) Dissolve the palladium precursor and oxide support in solvent I, and denote it as solution a; dissolve reducing agent I in deionized water, and denote it as solution b; The reducing agent I is one or more of sodium borohydride, potassium borohydride, and hydrazine hydrate. The molar ratio of reducing agent I to palladium is 10:1 to 2:

1. The amount of oxide support is calculated as 1 wt.% to 5 wt.% of palladium relative to the oxide support. (2) Add solution b dropwise to solution a and stir for several hours to form a precipitate; (3) After centrifuging and washing the obtained precipitate, it is redispersed in solvent II and denoted as solution c; (4) Dissolve the copper precursor in deionized water and denote it as solution d; mix solution d and solution c evenly to obtain a mixed solution; in the mixed solution, the molar ratio of palladium to copper is 0.1~10; (5) Dissolve reducing agent II in deionized water and denote it as solution e; add solution e dropwise to the mixed solution and stir for several hours to form a precipitate; The reducing agent II is one or more of ascorbic acid, aminoborane complex, diborane, and ethylene glycol, and the molar ratio of reducing agent II to copper is 10:1 to 2:

1. (6) The precipitate was centrifuged, washed, dried and ground into powder to obtain palladium-copper bimetallic nanocatalyst.

2. The palladium-copper bimetallic nanocatalyst according to claim 1, characterized in that, The size of the palladium-copper bimetallic nanocatalyst is 6 nm to 20 nm.

3. The palladium-copper bimetallic nanocatalyst according to claim 1, characterized in that, The oxide is one or more of silicon dioxide, aluminum oxide, titanium dioxide, zirconium oxide, and cerium oxide.

4. The method for preparing palladium-copper bimetallic nanocatalyst according to any one of claims 1-3, characterized in that, The steps are as follows: (1) Dissolve the palladium precursor and oxide support in solvent I, and denote it as solution a; dissolve reducing agent I in deionized water, and denote it as solution b; The reducing agent I is one or more of sodium borohydride, potassium borohydride, and hydrazine hydrate. The molar ratio of reducing agent I to palladium is 10:1 to 2:

1. The amount of oxide support is calculated as 1 wt.% to 5 wt.% of palladium relative to the oxide support. (2) Add solution b dropwise to solution a and stir for several hours to form a precipitate; (3) After centrifuging and washing the obtained precipitate, it is redispersed in solvent II and denoted as solution c; (4) Dissolve the copper precursor in deionized water and denote it as solution d; mix solution d and solution c evenly to obtain a mixed solution; in the mixed solution, the molar ratio of palladium to copper is 0.1~10; (5) Dissolve reducing agent II in deionized water and denote it as solution e; add solution e dropwise to the mixed solution and stir for several hours to form a precipitate; The reducing agent II is one or more of ascorbic acid, aminoborane complex, diborane, and ethylene glycol, and the molar ratio of reducing agent II to copper is 10:1 to 2:

1. (6) The precipitate was centrifuged, washed, dried and ground into powder to obtain palladium-copper bimetallic nanocatalyst.

5. The method for preparing palladium-copper bimetallic nanocatalyst according to claim 4, characterized in that, In step (1), the palladium precursor is one or more of palladium acetate, palladium chloride, palladium nitrate, palladium acetylacetone, and potassium tetrachloropalladate. Solvent I is one or more of deionized water, acetone, methanol, ethanol, and ethylene glycol, and the concentration of palladium in solution a is 0.05 mol / L to 1 mol / L.

6. The method for preparing palladium-copper bimetallic nanocatalyst according to claim 4, characterized in that, In step (2), the stirring speed is 400 r / min to 1000 r / min, and the stirring time is 1 h to 5 h; And / or, in step (5), the stirring speed is 400r / min to 1000r / min and the stirring time is 1h to 5h.

7. The method for preparing palladium-copper bimetallic nanocatalyst according to claim 4, characterized in that, In step (3), solvent II is one or more of deionized water, acetone, methanol, ethanol, and ethylene glycol; And / or, in step (4), the copper precursor is one or more of copper nitrate, copper chloride, copper sulfate, copper acetylacetone, and copper acetate.

8. The method for preparing palladium-copper bimetallic nanocatalyst according to claim 4, characterized in that, In step (3), the centrifugal washing method is as follows: centrifuge and wash 1 to 3 times with deionized water and anhydrous ethanol respectively; And / or, in step (6), the washing method is: centrifugation washing with deionized water and anhydrous ethanol 1 to 5 times respectively; the drying temperature is 60°C to 150°C, and the drying time is 5h to 24h.

9. The application of the palladium-copper bimetallic nanocatalyst according to any one of claims 1-3 in the synthesis of lower alcohols by hydrogenation of carbon dioxide.

10. The application of the palladium-copper bimetallic nanocatalyst according to claim 9 in the synthesis of lower alcohols by carbon dioxide hydrogenation, characterized in that, (1) The palladium-copper bimetallic nanocatalyst was subjected to hydrogen pre-reduction treatment. The pre-reduction treatment conditions were: space velocity of 3000 mL / g / h~10000 mL / g / h, temperature of 200°C~400°C, and reduction time of 0.5h~5h. (2) After the pre-reduction treated palladium-copper bimetallic nanocatalyst is pressed into tablets, crushed, and sieved to a particle size of 10-80 mesh, it is loaded into a fixed bed reactor for carbon dioxide hydrogenation reaction to obtain low carbon alcohol. The reaction conditions are as follows: reaction temperature 200°C~400°C, reaction pressure 2MPa~4MPa, space velocity 3000mL / g / h~8000mL / g / h, and the gas used is a mixture of CO2 and H2 with a volume ratio of 1:1~1:

5. The lower alcohol is one or more of methanol, ethanol, and propanol.

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