A metal Cu@ZnO x Core-shell structured nanocatalysts, their preparation methods and applications

Abstract

This invention relates to the field of carbon dioxide hydrogenation to methanol technology, and more particularly to a metallic Cu@ZnO. x Core-shell structured nanocatalysts, their preparation methods, and applications. The catalyst comprises a core-shell structure and a support: the core structure is metallic Cu nanoparticles, the shell structure is a thin layer of zinc oxide, and the support is alumina. The catalyst of this invention has an ultrathin zinc oxide (ZnO) layer on the surface of the metallic Cu nanoparticles. x Encapsulated within a core-shell structure, this catalyst exhibits a high methanol production rate in the low-temperature, low-pressure hydrogenation of carbon dioxide to methanol reaction. The preparation method of this catalyst is simple, reliable, and uses readily available raw materials, making it versatile.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide hydrogenation to methanol technology, and more particularly to a metallic Cu@ZnO. x Core-shell structured nanocatalysts, their preparation methods, and applications. Background Technology

[0002] With the rapid growth of global energy demand and the massive consumption of fossil fuels, large amounts of carbon dioxide (CO2) emissions are generated. Global climate change caused by CO2 as a greenhouse gas has become a serious global concern. Converting CO2 into valuable chemicals is an ideal way to alleviate this problem. CO2 molecules are thermodynamically stable, and if CO2 were the sole reactant, a large amount of energy would be required. However, it becomes thermodynamically easier if another substance with a higher Gibbs free energy (such as H2) is introduced as a co-reactant. Therefore, utilizing CO2 hydrogenation to prepare high-value chemicals such as oxygen-containing compounds (alcohols and dimethyl ethers) and hydrocarbons (olefins, liquid hydrocarbons, and aromatics) is one of the most promising conversion and utilization pathways.

[0003] Methanol (CH3OH) is an important chemical feedstock used as a fuel for internal combustion engines and fuel cells. With the depletion of non-renewable energy sources, methanol is also an alternative feedstock for the production of chemicals and even gasoline. Currently, with the successful development of active catalysts (zeolite-based catalysts), processes such as methanol-to-olefins (MTO) and methanol-to-propylene (MTP) have attracted significant attention. The market demand for methanol-derived fuels increased dramatically from 6% in 2011 to 22% in 2016. Therefore, CO2 conversion to methanol is one of the most attractive pathways for CO2 utilization and conversion.

[0004] Among the various catalysts developed to date for the hydrogenation of carbon dioxide to methanol (such as Cu-based catalysts, supported noble metal catalysts, and other types of catalysts), CuZnAl catalysts remain one of the most researched and industrially promising catalysts due to their relatively low cost and good reactivity. In CuZnAl catalysts prepared by traditional methods (such as co-precipitation), only a portion of the ZnO particles have interfacial contact with the CuO particles, resulting in Cu-ZnO... x The interfacial active sites are relatively few, leaving room for improvement in reactivity. Therefore, it is crucial to investigate new catalyst preparation methods to optimize the interfacial structure of CuZnAl catalysts, thereby enhancing the methanol production rate from carbon dioxide hydrogenation.

[0005] To improve the methanol production rate of Cu-based catalysts, researchers have undertaken numerous studies. One approach involves adding promoters (such as alkali metals, alkaline earth metals, and rare earth metals) to enhance methanol production activity. For example, cerium oxide doping can promote the bonding between Cu and CO, making CO desorption from the surface difficult, thereby inhibiting the reverse water-gas exchange reaction and methanol decomposition, while selectively promoting methanol synthesis. Another approach is to select suitable support materials (such as zirconium oxide or cerium oxide) to adjust the catalyst surface pH and Cu electronic states, thus influencing the adsorption and activation of CO2 and H2, and further improving the methanol synthesis performance of Cu-based catalysts. Furthermore, covering the surface of metal nanoparticles with oxides (such as SiO2) to form a core-shell structure can effectively prevent the growth and aggregation of metal particles, and its good metal dispersion can improve catalytic performance. However, these methods involve high raw material costs or complex preparation processes, making it difficult to achieve large-scale catalyst production, and therefore hindering the widespread industrial application. Summary of the Invention

[0006] The purpose of this invention is to provide a metallic Cu@ZnO x Core-shell structured nanocatalysts, their preparation method, and applications: The preparation method is simple and reliable, and can be used in the low-temperature, low-pressure carbon dioxide hydrogenation to methanol reaction. The core-shell structure of this catalyst can provide more Cu-ZnO. x Interfacial active sites, thereby increasing the methanol production rate of Cu-based catalysts.

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

[0008] This invention provides a metallic Cu@ZnO x A core-shell structured nanocatalyst, comprising a core-shell structure and a support: the core structure is metallic Cu nanoparticles, the shell structure is a zinc oxide thin layer, and the support is aluminum oxide, denoted as Cu@ZnO. x / Al2O3.

[0009] In the above technical solution, the catalyst particle size is further directly related to the loading of metallic Cu, and the loading is the mass loading, which is calculated as the mass of metal / the total mass of catalyst; the particle size of the metallic Cu nanoparticles is 5-50 nm, and the metallic Cu nanoparticles account for 4-90% of the total mass of the catalyst by mass fraction.

[0010] In the above technical solution, the zinc oxide composition is further denoted as ZnO. x The thickness is controllable and at the nanoscale, within 1 nm.

[0011] In the above technical solution, the alumina carrier is further described as amorphous alumina or γ-type alumina.

[0012] Another aspect of the present invention provides a method for preparing the above-mentioned core-shell structured nanocatalyst, the method comprising the following steps:

[0013] (1) Dissolve the copper precursor and aluminum precursor in water at a copper-aluminum molar ratio of 0.03-8.50:1, stir until homogeneous to obtain a mixed solution, add the mixed solution dropwise to a sodium carbonate solution at 65℃ under stirring, wash the precipitate with deionized water and dry it, and treat the obtained powder at 500℃ and pure H2 atmosphere for 2-4 hours at a flow rate of 50-100 ml / min to obtain Cu / Al2O3 sample;

[0014] (2) Separate the Cu / Al2O3 sample obtained in step (1) and the zinc source solid powder with quartz wool, place them in a quartz reaction tube with the zinc source at the front end and the Cu / Al2O3 sample at the rear end, and treat them in a carbon dioxide hydrogen atmosphere at 450°C for 1-200 h to obtain the core-shell structure catalyst.

[0015] In the above technical solution, further, in step (1), the metallic copper precursor is at least one of copper nitrate, chlorate, acetate, and sulfate;

[0016] The aluminum precursor is at least one of aluminum nitrate, chlorate, and sulfate.

[0017] In the above technical solution, further, in step (1), the drying temperature is 110℃ and the drying time is 12-24h.

[0018] In the above technical solution, further, in step (2), the zinc source is at least one of zinc oxide and metallic zinc.

[0019] In the above technical solution, further, in step (2), the separation distance between the Cu / Al2O3 sample and the zinc source is 2mm-1cm.

[0020] In the above technical solution, further, in step (2), the thickness of the shell is adjusted by changing the processing time. The longer the time, the thicker the shell. The preferred processing time is 100-150h.

[0021] In the above technical solution, the carbon dioxide hydrogenation atmosphere is a mixture of carbon dioxide and hydrogen in a volume ratio of 1 / 199-1 / 3 containing an inert gas; the inert gas is at least one of high-purity Ar and high-purity N2.

[0022] In another aspect, the present invention provides the application of the above-mentioned core-shell structured nanocatalyst in the hydrogenation of carbon dioxide to methanol, wherein the reaction conditions are: pressure 2-4 MPa, reaction gas flow rate 20-100 mL / min, and reaction temperature 200-260 °C.

[0023] The beneficial effects of this invention are as follows:

[0024] 1. The catalyst of this invention has a surface coated with an ultrathin layer of zinc oxide (ZnO) on the surface of the metal Cu nanoparticles. x Encapsulated by a core-shell structure, ZnO exhibits a core-shell structure that can be controlled by adjusting the processing time. x The shell thickness allows for precise control of Cu and ZnO. x The catalyst achieves an optimal number of active sites at its contact interface. Therefore, it exhibits a high methanol production rate in the low-temperature, low-pressure carbon dioxide hydrogenation to methanol reaction.

[0025] 2. The preparation method of this invention is simple, uses inexpensive raw materials, has strong versatility, and has great application potential. Attached Figure Description

[0026] Figure 1 The images show the X-ray diffraction pattern and transmission electron microscope (TEM) image of the sample in Example 1. a is the X-ray diffraction pattern and b is the TEM image.

[0027] Figure 2 The images shown are dark-field high-resolution scanning transmission electron microscope (STEM) images and energy-dispersive X-ray spectroscopy (EDS) elemental distribution maps of the sample in Example 1. Image a is a dark-field STEM image, and image b is an EDS elemental distribution map.

[0028] Figure 3 The images show the Auger spectra of the samples excited by X-rays in Example 1. a is the LMM Auger spectrum of Zn, and b is the LMM Auger spectrum of Cu.

[0029] Figure 4 The images shown are dark-field high-resolution scanning transmission electron microscope (STEM) images and energy-dispersive X-ray spectroscopy (EDS) elemental distribution maps of the samples in Example 4. Image a is a dark-field STEM image, and image b is an EDS elemental distribution map.

[0030] Figure 5 The graph shows the methanol formation rate of the sample in Example 5 and the commercial CuZnAl catalyst in the carbon dioxide hydrogenation reaction.

[0031] Figure 6 This is a stability test diagram of the sample in Example 5 and the commercial CuZnAl catalyst in the carbon dioxide hydrogenation reaction. Detailed Implementation

[0032] The present invention will now be described in detail through embodiments, but the scope of the claims is not limited to these embodiments. Furthermore, the embodiments only provide some conditions for achieving this objective and do not imply that all conditions must be met to achieve this objective.

[0033] Example 1

[0034] (1) Dissolve 25 g of copper nitrate nonahydrate and 6.85 g of aluminum nitrate trihydrate in water and stir until homogeneous to obtain a mixed solution. Add the mixed solution dropwise to a sodium carbonate solution at 65°C under stirring. After washing the precipitate with deionized water, dry it in an oven at 110°C for 12-24 h. The powder obtained after drying is treated in pure H2 at 500°C for 4 h at a flow rate of 80 ml / min to obtain a Cu / Al2O3 sample.

[0035] (2) The aforementioned 0.15 g Cu / Al2O3 sample and 0.3 g zinc oxide particles were separated by quartz wool at a distance of approximately 3 mm and placed in a quartz reaction tube with the zinc oxide particles at the front end and the Cu / Al2O3 sample at the rear end. The mixture was treated at 450 °C in a 0.5% CO2 / H2 atmosphere for 100 h. The Cu / Al2O3 separated at the rear end yielded approximately 69 wt% Cu@ZnO. x / Al2O3 core-shell structure catalyst.

[0036] 69wt% Cu@ZnO in Example 1 x X-ray diffraction pattern of Al2O3 core-shell structure ( Figure 1 a) and transmission electron microscopy ( Figure 1 b) Characterization showed that the synthesized catalyst contained Cu particles supported on amorphous alumina with a particle size of approximately 30 nm. High-resolution scanning transmission electron microscopy in dark-field mode (STEM) Figure 2 a) and the elemental distribution of the corresponding energy spectrum ( Figure 2 b) Analysis showed that the surface of Cu nanoparticles was coated with a Zn-containing oxide layer with a thickness of about 1 nm, which is a typical core-shell structure. Quasi-in-situ X-ray excited Auger spectroscopy showed that the Cu particle surface was in a reduced state, while the Zn species in the surface coating were in an oxidized state. Figure 3 ).

[0037] Example 2

[0038] (1) Dissolve 0.1 g of copper nitrate nonahydrate and 5 g of aluminum nitrate trihydrate in water and stir until homogeneous to obtain a mixed solution. Add the mixed solution dropwise to a 65°C sodium carbonate solution under stirring. The precipitate is washed with deionized water and then dried in a 110°C oven for 12-24 h. The powder obtained after drying is treated in pure H2 at 500°C for 4 h at a flow rate of 80 ml / min to obtain a Cu / Al2O3 sample.

[0039] (2) The aforementioned 0.15 g Cu / Al2O3 sample and 0.3 g zinc oxide particles were separated by quartz wool at a distance of approximately 3 mm and placed in a quartz reaction tube with the zinc oxide particles at the front end and the Cu / Al2O3 sample at the rear end. The mixture was treated at 450 °C in a 0.5% CO2 / H2 atmosphere for 100 h. The Cu / Al2O3 separated at the rear end yielded approximately 4 wt% Cu@ZnO. x / Al2O3 core-shell structure catalyst. The average size of Cu particles in the catalyst of Example 2 is approximately 5 nm.

[0040] Example 3

[0041] (1) Dissolve 25 g of copper nitrate nonahydrate and 5 g of aluminum nitrate trihydrate in water and stir until homogeneous to obtain a mixed solution. Add the mixed solution dropwise to a 65°C sodium carbonate solution under stirring. The precipitate is washed with deionized water and then dried in an oven at 110°C for 12-24 h. The powder obtained after drying is treated in pure H2 at 500°C for 4 h at a flow rate of 80 ml / min to obtain a Cu / Al2O3 sample.

[0042] (2) The aforementioned 0.15 g Cu / Al2O3 sample and 0.3 g zinc oxide particles were separated by quartz wool at a distance of approximately 3 mm and placed in a quartz reaction tube with the zinc oxide particles at the front end and the Cu / Al2O3 sample at the rear end. The mixture was treated at 450 °C in a 0.5% CO2 / H2 atmosphere for 100 h. The Cu / Al2O3 separated at the rear end yielded approximately 90 wt% Cu@ZnO. x / Al2O3 core-shell structure catalyst. The average size of Cu particles in the catalyst of Example 3 is about 50 nm.

[0043] Example 4

[0044] (1) Dissolve 25 g of copper nitrate nonahydrate and 6.85 g of aluminum nitrate trihydrate in water and stir until homogeneous to obtain a mixed solution. Add the mixed solution dropwise to a 65°C sodium carbonate solution under stirring. The precipitate is washed with deionized water and then dried in an oven at 110°C for 12-24 h. The powder obtained after drying is treated in pure H2 at 500°C for 4 h at a flow rate of 80 ml / min to obtain a Cu / Al2O3 sample.

[0045] (2) The aforementioned 0.15 g Cu / Al2O3 sample and 0.3 g zinc oxide particles were separated by quartz wool at a distance of approximately 3 mm and placed in a quartz reaction tube with the zinc oxide particles at the front end and the Cu / Al2O3 sample at the rear end. The mixture was treated at 450 °C in a 0.5% CO2 / H2 atmosphere for 60 h. The separated Cu / Al2O3 at the rear end could also yield approximately 87 wt% Cu@ZnO. x / Al2O3 core-shell structure catalyst. The Cu particle size in the catalyst of Example 4 is around 30 nm.

[0046] High-resolution scanning transmission electron microscopy in dark field mode ( Figure 4 a) and the elemental distribution of the corresponding energy spectrum ( Figure 4 b) Analysis showed that the surface of Cu nanoparticles was coated with Zn-containing oxides, and the core-shell structure was similar to that of the sample in Example 1, but the shell thickness was about 0.6 nm. The shell thickness could be controlled by changing the pretreatment conditions.

[0047] Example 5

[0048] (1) Dissolve 25 g of copper nitrate nonahydrate and 6.85 g of aluminum nitrate trihydrate in water and stir until homogeneous to obtain a mixed solution. Add the mixed solution dropwise to a sodium carbonate solution at 65°C under stirring. After washing the precipitate with deionized water, dry it in an oven at 110°C for 12-24 h. The powder obtained after drying is treated in pure H2 at 500°C for 4 h at a flow rate of 80 ml / min to obtain a Cu / Al2O3 sample.

[0049] (2) The aforementioned 0.15 g Cu / Al2O3 sample and 0.3 g zinc oxide particles were separated by quartz wool at a distance of approximately 3 mm and placed in a quartz reaction tube with the zinc oxide particles at the front end and the Cu / Al2O3 sample at the rear end. The mixture was treated at 450 °C in a 0.5% CO2 / H2 atmosphere for 150 h. The separated Cu / Al2O3 sample at the rear end could also yield approximately 67 wt% Cu@ZnO. x / Al2O3 core-shell structure catalyst. In the catalyst of Example 5, the Cu particle size is about 30 nm and the shell thickness is about 0.7 nm.

[0050] Example 6

[0051] (1) Dissolve 25 g of copper nitrate nonahydrate and 6.85 g of aluminum nitrate trihydrate in water and stir until homogeneous to obtain a mixed solution. Add the mixed solution dropwise to a sodium carbonate solution at 65°C under stirring. After washing the precipitate with deionized water, dry it in an oven at 110°C for 12-24 h. The powder obtained after drying is treated in pure H2 at 500°C for 4 h at a flow rate of 80 ml / min to obtain a Cu / Al2O3 sample.

[0052] (2) The aforementioned 0.15 g Cu / Al2O3 sample and 0.3 g metallic Zn particles were separated by quartz wool at a distance of approximately 3 mm and placed in a quartz reaction tube with the metallic Zn particles at the front and the Cu / Al2O3 sample at the rear. The mixture was treated at 450 °C in a 0.5% CO2 / H2 atmosphere for 1 h. The separated Cu / Al2O3 sample at the rear could also yield approximately 87 wt% Cu@ZnO.x / Al2O3 core-shell structure catalyst. The Cu particles in the catalyst are about 30 nm in size, and the shell thickness is about 0.2 nm.

[0053] Example 7

[0054] 1. Weigh 67 wt% Cu@ZnO from Example 5 x 100 mg of Al₂O₃ catalyst was loaded into a miniature vertical fixed-bed quartz tube reactor. Pure hydrogen was purged at 20 mL / min, and the reactor was pretreated at 250 °C for 2 h. The mixture was then kept at 250 °C to produce a carbon dioxide hydrogenation reaction gas (24% CO₂ / 72% H₂ / 4% N₂), pressurized to 3.0 MPa, and maintained at a flow rate of 20 mL / min. The product was analyzed online using an Agilent GC8890 chromatograph equipped with an HP-INNOWax column and a thermal conductivity detector. The methanol formation rate (TOF) of methanol after 2 h of reaction was recorded and calculated (TOF of methanol formation: the conversion frequency of methanol formation at a single active site).

[0055] 2. Weigh 100 mg of commercial CuZnAl catalyst (Sichuan Shutai, low-pressure methanol synthesis catalyst SCST-253-55) and load it into a micro vertical fixed-bed quartz tube reactor. Pretreat at 250℃ for 2 h with pure hydrogen at a flow rate of 20 mL / min. Maintain a constant temperature of 250℃, switch to carbon dioxide hydrogenation reaction gas (24% CO2 / 72% H2 / 4% N2), pressurize to 3.0 MPa, and maintain a gas flow rate of 20 mL / min. Analyze the product online using an Agilent GC8890 chromatogram equipped with an HP-INNOWax column and a thermal conductivity detector. Record the methanol formation rate after 2 h of reaction.

[0056] Figure 5 It is the 67wt% Cu@ZnO in Example 5 x Evaluation results of methanol production rates for the carbon dioxide hydrogenation reaction using Al2O3 catalyst and commercial CuZnAl catalyst. It can be seen that the methanol conversion frequency of the commercial CuZnAl catalyst is 102.8 h⁻¹, while that of the 67 wt% Cu@ZnO catalyst is significantly higher. x The methanol production rate of the Al2O3 catalyst was 123.1 h⁻¹. -1 Its performance is superior to that of commercial CuZnAl catalysts. These results demonstrate that Cu@ZnO... x Al2O3 core-shell catalysts can serve as excellent catalysts for the hydrogenation of carbon dioxide to methanol, and have potential value for industrial applications.

[0057] Example 8

[0058] 1. Weigh 67 wt% Cu@ZnO from Example 5 x100 mg of Al₂O₃ catalyst was loaded into a miniature vertical fixed-bed quartz tube reactor. Pure hydrogen was purged at 20 mL / min, and the reactor was pretreated at 250 °C for 2 h. The temperature was then maintained at 250 °C, and the flow rate was increased to 3.0 MPa with a gas flow rate of 20 mL / min. The product was analyzed online using an Agilent GC8890 chromatograph equipped with an HP-INNOWax column and a thermal conductivity detector. The reaction was carried out for 30 h, and the methanol formation rate was monitored.

[0059] 2. Weigh 100 mg of commercial CuZnAl catalyst (Sichuan Shutai, low-pressure methanol synthesis catalyst SCST-253-55) and load it into a micro vertical fixed-bed quartz tube reactor. Pretreat at 250℃ for 2 h by passing pure hydrogen at 20 mL / min. Maintain a constant temperature of 250℃, switch to carbon dioxide hydrogenation reaction gas (24% CO2 / 72% H2 / 4% N2), pressurize to 3.0 MPa, and maintain a gas flow rate of 20 mL / min. Analyze the product online using an Agilent GC8890 chromatogram equipped with an HP-INNOWax column and a thermal conductivity detector. Monitor the methanol formation rate for 30 h of reaction.

[0060] Figure 6 It is the 67wt% Cu@ZnO in Example 5 x Stability evaluation results of Al2O3 catalyst and commercial CuZnAl catalyst for carbon dioxide hydrogenation reaction. It can be seen that after 30 hours of testing, the 67wt% Cu@ZnO catalyst... x The stability of the Al2O3 catalyst is comparable to that of the commercial CuZnAl catalyst.

[0061] In summary, the beneficial effects of this invention are: direct synthesis of metallic Cu@ZnO. x Core-shell structured nanocatalysts overcome the shortcomings of previous core-shell materials, which required numerous raw materials and could not controllably modify metal nanoparticles at the nanoscale, thus exhibiting excellent versatility. Furthermore, Cu@ZnO is used as a catalyst in the low-temperature, low-pressure hydrogenation of carbon dioxide to methanol reaction. x The core-shell structure has the best Cu-ZnO x Increasing the number of interfacial active sites can significantly improve the methanol production rate of Cu-based catalysts in the carbon dioxide hydrogenation reaction, and has great application potential.

[0062] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the implementation. The scope of protection of the present invention should be determined by the scope defined in the claims. Other variations or modifications can be made based on the above description. Obvious variations or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A metallic Cu@ZnO x A method for preparing core-shell structured nanocatalysts, characterized in that, The catalyst comprises a core-shell structure and a support: the core structure is metallic Cu nanoparticles, the shell structure is a thin layer of zinc oxide, and the support is aluminum oxide. The method includes the following steps: (1) Dissolve the copper precursor and aluminum precursor in water at a copper-aluminum molar ratio of 0.03-8.50:1, stir until homogeneous to obtain a mixed solution, add the mixed solution dropwise to a sodium carbonate solution at 65 °C under stirring, wash the precipitate with deionized water and dry it, and treat the obtained powder at 500 °C in a pure H2 atmosphere for 2-4 h at a flow rate of 50-100 mL / min to obtain Cu / Al2O3 sample; (2) Separate the Cu / Al2O3 sample obtained in step (1) and the zinc source solid powder with quartz wool, place them in a quartz reaction tube with the zinc source at the front end and the Cu / Al2O3 sample at the rear end, and treat them in a carbon dioxide hydrogen atmosphere at 450 °C for 1-200 h to obtain the core-shell structure catalyst.

2. The preparation method according to claim 1, characterized in that: The Cu nanoparticles have a particle size of 5 nm-50 nm and account for 4%-90% of the total mass of the catalyst by mass fraction. The thickness of the zinc oxide thin layer is within 1 nm.

3. The preparation method according to claim 1, characterized in that: The alumina carrier is amorphous alumina or γ-type alumina.

4. The preparation method according to claim 1, characterized in that: In step (1), the metallic copper precursor is at least one of copper nitrate, acetate, and sulfate; The aluminum precursor is at least one of aluminum nitrate and sulfate.

5. The preparation method according to claim 1, characterized in that: In step (1), the drying temperature is 110℃ and the drying time is 12-24 h.

6. The preparation method according to claim 1, characterized in that: In step (2), the zinc source is at least one of zinc oxide and metallic zinc.

7. The preparation method according to claim 1, characterized in that: In step (2), the separation distance between the Cu / Al2O3 sample and the zinc source is 2 mm-1 cm.

8. The preparation method according to claim 1, characterized in that: The carbon dioxide hydrogenation atmosphere is a mixture of carbon dioxide and hydrogen in a volume ratio of 1 / 199 to 1 / 3, containing an inert gas; the inert gas is at least one of high-purity Ar and high-purity N2.

9. The application of a core-shell structured nanocatalyst prepared by the method according to any one of claims 1-8 in the hydrogenation of carbon dioxide to methanol, characterized in that, The reaction conditions are: pressure 2-4 MPa, reaction gas flow rate 20-100 mL / min, and reaction temperature 200-260 ℃.

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