A catalyst for efficiently catalyzing carbon dioxide hydrogenation to produce methanol and a preparation method thereof

Abstract

This invention discloses a highly efficient catalyst for the catalytic hydrogenation of carbon dioxide to methanol and its preparation method, belonging to the field of catalyst technology. The highly efficient catalyst for the catalytic hydrogenation of carbon dioxide to methanol consists of a zirconium oxide support and zinc monopores supported on the surface of the zirconium oxide support, wherein the zirconium oxide support and the zinc monopores are connected by Zn-O-Zr coordination bonds. The highly efficient catalyst for the catalytic hydrogenation of carbon dioxide to methanol of this invention exhibits higher methanol selectivity and carbon dioxide conversion rate, and can achieve a high space-time yield (>1000 mmol). MeOH h ‑1 g Zn ‑1 Furthermore, the preparation process described in this invention is simple, easy to operate, and easy to repeat, and has good application prospects.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a highly efficient catalyst for the hydrogenation of carbon dioxide to methanol and its preparation method. Background Technology

[0002] The massive emissions of carbon dioxide have caused numerous environmental problems, but carbon dioxide is also a valuable carbon resource. Transforming harmful carbon dioxide into high-value-added chemicals is a promising approach to addressing both environmental and energy issues. Combining carbon dioxide with green hydrogen to produce methanol not only perfectly embodies the concepts of a "methanol economy" and "liquid sunshine," but also solves the problem of massive carbon dioxide emissions caused by the current fossil fuel-based methanol synthesis, further reducing our dependence on traditional fossil fuels.

[0003] The design and synthesis of highly efficient catalysts are key to the production of methanol from carbon dioxide.

[0004] Currently, Cu-ZnO-Al2O3 catalysts are the main catalysts used in industrial applications for the hydrogenation of carbon dioxide to methanol. However, Cu-based catalysts suffer from deactivation and low selectivity (<60%). Therefore, composite oxide catalysts with high stability and methanol selectivity, such as ZnO-ZrO2 and In2O3-ZrO2, have attracted attention. Among them, ZnO-ZrO2 catalysts have been used in solar water electrolysis to produce H2 and in a 1000-ton industrial demonstration project for CO2 hydrogenation to methanol. This shows that ZnO-ZrO2 catalysts have great application potential, but the problem of low CO2 conversion rate still needs to be solved. Therefore, improving CO2 conversion rate while ensuring high methanol selectivity and lifespan is the main problem currently facing catalysts for the hydrogenation of carbon dioxide to methanol. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a highly efficient catalyst for the catalytic hydrogenation of carbon dioxide to methanol and a method for its preparation. The highly efficient catalyst for the catalytic hydrogenation of carbon dioxide to methanol exhibits excellent catalytic activity and selectivity, and can achieve a high space-time yield (>1000 mmol). MeOH h -1 g Zn -1 ).

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] This invention provides a highly efficient catalyst for the hydrogenation of carbon dioxide to methanol, which consists of a zirconium oxide support and a unit zinc dot supported on the surface of the zirconium oxide support.

[0008] The zirconium oxide support and the unit zinc spot are connected by Zn-O-Zr coordination bonds.

[0009] The catalysts mentioned above for the efficient catalytic hydrogenation of carbon dioxide to methanol contain only Zn-O-Zr coordination bonds.

[0010] The unit point zinc described in this invention refers to zinc ions that contain only Zn-O-Zr and lack Zn-O-Zn or Zn-Zn coordination environments.

[0011] The zinc ion at the unit point is preferably a zinc ion with a valence state of 0 < chemical valence < 2.

[0012] Preferably, the zinc loading per unit spot is 0.07 wt% to 6 wt%; more preferably, it is 0.5 wt% to 5 wt%. In some specific embodiments of the present invention, the zinc loading per unit spot is specifically 1.08 wt%, 4.13 wt%, 0.81 wt%, 2.77 wt%, or 0.86 wt%.

[0013] This invention also provides a method for preparing a highly efficient catalyst for the hydrogenation of carbon dioxide to methanol, comprising the following steps:

[0014] 1) A zirconium salt solution was mixed with a precipitant and subjected to a constant-temperature precipitation reaction to obtain a zirconium oxide precursor, which was then heat-treated to prepare a zirconium oxide support.

[0015] 2) Add ammonia to the zinc salt solution and adjust the pH until the precipitate formed in the solution is completely dissolved to obtain a solution of tetraamminezinc hydroxide;

[0016] 3) The zirconium oxide support obtained in step 1) is mixed with the solution of tetraamminezinc hydroxide obtained in step 2) and then dried to obtain the catalyst precursor;

[0017] 4) The catalyst precursor obtained in step 3) is calcined to obtain a highly efficient catalyst for the hydrogenation of carbon dioxide to methanol.

[0018] In the above preparation method, tetraamminezinc ions are used as the zinc source for the highly efficient catalyst for the hydrogenation of carbon dioxide to methanol.

[0019] Preferably, in step 3), after the zirconium oxide support is mixed with the solution of tetraamminezinc hydroxide, hydroxide ions will accumulate on the surface of the zirconium oxide support.

[0020] Preferably, the hydroxide ions are partly derived from excess hydroxide ions in the solution of tetraamminezinc hydroxide, and partly from hydroxide ions formed by defects in zirconium oxide itself.

[0021] The hydroxide ions aggregated on the surface of the zirconium oxide support combine with tetraamminezinc ions through strong electrostatic adsorption to obtain the catalyst precursor.

[0022] In step 3) of the above preparation method, the surface loading of the zirconium oxide support is controlled between 1 and 1500 μm. 2 / L.

[0023] In some specific embodiments of the present invention, the surface loading of the zirconium oxide support is preferably 1000 m. 2 / L.

[0024] The present invention does not have any particular limitation on the drying method in step 3), and any method known to those skilled in the art is acceptable.

[0025] In some specific embodiments of the present invention, atmospheric pressure drying is preferred.

[0026] The drying temperature is preferably 40°C to 80°C, more preferably 60°C.

[0027] The drying time is preferably 10 to 14 hours, more preferably 12 hours.

[0028] The drying process in step 3) also includes washing and filtration.

[0029] The present invention does not specifically limit the solvent used for washing and the method of filtration, both of which are solvents and methods well known to those skilled in the art.

[0030] In this invention, the washing before drying is preferably done with deionized water.

[0031] The filtration after washing is preferably vacuum filtration. Preferably, the zirconium salt solution in step 1) is selected from one or more of zirconium nitrate solution, zirconium chloride solution, zirconium oxychloride solution, zirconium citrate solution, zirconium sulfate solution, and zirconium carbonate solution; more preferably, the zirconium salt solution in step 1) is selected from one or more of zirconium nitrate solution, zirconium chloride solution, and zirconium oxychloride solution; and even more preferably, zirconium nitrate solution.

[0032] Preferably, the precipitant in step 1) is selected from one or more of ammonium carbonate, ammonia, and sodium carbonate; more preferably, it is ammonia.

[0033] Preferably, the temperature of the isothermal precipitation reaction in step 1) is 30℃~100℃; more preferably, it is 70℃.

[0034] Preferably, the isothermal precipitation reaction time is selected from 1 to 48 hours; more preferably, it is 3 to 20 hours. In some specific embodiments of the present invention, 3 hours is preferred.

[0035] The preferred temperature for heat treatment in step 1) is 300℃ to 700℃; more preferably 500℃.

[0036] The heating rate of the heat treatment is preferably 2 to 10 °C / min; more preferably 5 °C / min.

[0037] The heat treatment time is preferably 1 to 5 hours; more preferably 3 hours.

[0038] Preferably, the zinc salt solution in step 2) is selected from one or more of zinc nitrate solution, zinc chloride solution, zinc sulfate solution, zinc oxychloride solution, and zinc acetate solution; more preferably, it is one or more of zinc nitrate solution, zinc chloride solution, and zinc sulfate solution; and even more preferably, it is zinc nitrate solution.

[0039] Preferably, the pH in step 2) is selected from 9 to 12. In some specific embodiments of the present invention, the pH in step 2) is selected from 9, 10, or 11.5.

[0040] Preferably, in step 3), the molar ratio of tetraamminezinc hydroxide to zirconium oxide support is (1-50):1; more preferably, it is (2-20):1. In some specific embodiments of the present invention, the molar ratio of tetraamminezinc hydroxide to zirconium oxide support in step 3) is 2:1, 5:1, 10:1, or 20:1.

[0041] Preferably, the calcination temperature in step 4) of this invention is 300℃~700℃; more preferably, it is 400℃~600℃. In some specific embodiments of this invention, preferably, the calcination temperature is 500℃.

[0042] Preferably, the calcination time is 1 to 5 hours; more preferably, it is 2 to 4 hours. In some specific embodiments of the present invention, preferably, the calcination time is 3 hours.

[0043] Preferably, the heating rate of the calcination is 2–10 °C / min; more preferably, it is 5–10 °C / min. In some specific embodiments of the present invention, preferably, the heating rate of the calcination is 5 °C / min.

[0044] The present invention also provides a method for producing methanol by carbon dioxide hydrogenation, wherein the method employs the above-mentioned highly efficient catalyst for producing methanol by carbon dioxide hydrogenation or the highly efficient catalyst for producing methanol by carbon dioxide hydrogenation prepared by the above-mentioned preparation method.

[0045] In the above method for producing methanol by hydrogenation of carbon dioxide, the volume ratio of carbon dioxide to hydrogen is preferably 1:(1-10); more preferably 1:(2-4). In some specific embodiments of the present invention, it is specifically 1:3.

[0046] In the method for producing methanol by carbon dioxide hydrogenation, the preferred carbon dioxide flow rate to catalyst mass ratio is (10-50) mL / min:300 mg; more preferably, it is (20-40) mL / min:300 mg. In some specific embodiments of the present invention, it is specifically 30 mL / min:300 mg.

[0047] In the method for producing methanol by carbon dioxide hydrogenation, the reaction temperature is preferably 200℃~400℃; more preferably 220℃~320℃. In some specific embodiments of the present invention, the temperature is specifically 250℃, 275℃, or 300℃.

[0048] In the method for producing methanol by hydrogenation of carbon dioxide, the reaction pressure is preferably 1-5 MPa; more preferably 2-3 MPa.

[0049] Compared with existing technologies, the highly efficient catalytic catalyst for the hydrogenation of carbon dioxide to methanol provided by this invention consists of a zirconium oxide support and a single zinc dot supported on the surface of the zirconium oxide support, wherein the zirconium oxide support and the single zinc dot are connected by Zn-O-Zr coordination bonds. The highly efficient catalytic catalyst for the hydrogenation of carbon dioxide to methanol of this invention exhibits higher methanol selectivity and carbon dioxide conversion rate, and can achieve a high space-time yield (>1000 mmol). MeOH h -1 g Zn -1 Furthermore, the preparation process described in this invention is simple, easy to operate, and easy to repeat, and has good application prospects. Attached Figure Description

[0050] Figure 1 X-ray diffraction pattern of the zirconia material prepared in Example 1;

[0051] Figure 2 X-ray diffraction pattern of the zirconium oxide-supported single-site zinc catalyst prepared in Example 1;

[0052] Figure 3 The X-ray absorption spectrum of the zirconium oxide-supported zinc catalyst prepared in Example 1 is shown below.

[0053] Figure 4 The fine structure X-ray absorption spectrum of the zirconium oxide-supported single-site zinc catalyst prepared in Example 1 is shown.

[0054] Figure 5 The graphs show the activity of the zirconium oxide support and the zirconium oxide-supported single-point zinc catalyst prepared in Example 1 and the zinc-zirconium composite metal oxide catalyst prepared in Comparative Example 1. The bar graphs represent methanol selectivity, and the triangles, pentagrams, and circles represent carbon dioxide conversion.

[0055] Figure 6X-ray diffraction pattern of the zirconium oxide-supported single-site zinc catalyst prepared in Example 2;

[0056] Figure 7 The graphs show the activity of the zirconium oxide support and the zirconium oxide-supported zinc catalyst prepared in Example 2, where the bar graph represents methanol selectivity and the pentagram represents carbon dioxide conversion.

[0057] Figure 8 X-ray diffraction pattern of the zirconium oxide-supported single-site zinc catalyst prepared in Example 3;

[0058] Figure 9 The graphs show the activity of the zirconium oxide support and the zirconium oxide-supported zinc catalyst prepared in Example 3, where the bar graph represents methanol selectivity and the pentagram represents carbon dioxide conversion.

[0059] Figure 10 X-ray diffraction pattern of the zirconium oxide-supported single-site zinc catalyst prepared in Example 4;

[0060] Figure 11 The graphs show the activity of the zirconium oxide support and the zirconium oxide-supported zinc catalyst prepared in Example 4, where the bar graph represents methanol selectivity and the pentagram represents carbon dioxide conversion.

[0061] Figure 12 X-ray diffraction pattern of the zirconium oxide-supported single-site zinc catalyst prepared in Example 5;

[0062] Figure 13 The graphs show the activity of the zirconium oxide support and the zirconium oxide-supported zinc catalyst prepared in Example 5, where the bar graph represents methanol selectivity and the pentagram represents carbon dioxide conversion.

[0063] Figure 14 X-ray diffraction pattern of the zirconium oxide-supported single-site zinc catalyst prepared in Example 6;

[0064] Figure 15 The graphs show the activity of the zirconium oxide support and the zirconium oxide-supported zinc catalyst at a single point, prepared in Example 6. The bar graphs represent methanol selectivity, and the pentagrams represent carbon dioxide conversion. Detailed Implementation

[0065] To further illustrate the present invention, the following detailed description of the highly efficient catalyst for the hydrogenation of carbon dioxide to methanol and its preparation method provided by the present invention is given in conjunction with embodiments.

[0066] The following reagents, including zirconium nitrate, zinc nitrate, ammonia, and ammonium carbonate, are all commercially available products.

[0067] Example 1

[0068] Weigh 10g of zirconium nitrate and dissolve it in deionized water. Stir in an oil bath at 70℃ and add ammonia precipitant at a uniform rate until the pH reaches 7. After centrifugation and washing, dry at 80℃ for 16h and place in a muffle furnace to calcine at 500℃ for 3h at a heating rate of 5℃ / min. After cooling to room temperature, grind the obtained zirconium oxide support into powder for later use.

[0069] Weigh 1.0 g of zinc nitrate and dissolve it in 100 mL of deionized water to prepare a metal salt solution. Slowly add ammonia water while stirring at a constant speed until the pH equals 10 to obtain the precursor solution.

[0070] Weigh 3.9g of zirconium oxide support and slowly add it to the precursor solution. Stir continuously at room temperature for three hours, filter and wash repeatedly three times, and dry at 60 degrees Celsius for 12 hours to obtain the calcined precursor.

[0071] The calcined precursor was placed in a muffle furnace and heated to 500°C in air at a heating rate of 5°C / min. After holding at this temperature for 3 hours, it was naturally cooled to obtain a zirconium oxide-supported zinc catalyst with a zinc loading of 1.08 wt%.

[0072] The obtained zirconium oxide support material was analyzed using X-ray diffraction, and the results are as follows: Figure 1 As shown, the results indicate that there are four main diffraction peaks, which correspond to the (011), (-111), (111) and (002) crystal planes of the zirconia material, respectively, confirming that the crystal structure is monoclinic zirconia.

[0073] The final zirconium oxide-supported single-point zinc catalyst was analyzed by X-ray diffraction, and the results are as follows: Figure 2 As shown, the results indicate that the X-ray diffraction pattern of the zirconia-supported single-site zinc catalyst is similar to that of the standard monoclinic zirconia. Figure 1 No other XRD diffraction peaks related to zinc were observed.

[0074] The final prepared zirconium oxide-supported zinc catalyst was analyzed by X-ray absorption spectroscopy, and the results are as follows: Figure 3 As shown, the results indicate that the R space of the X-ray absorption spectrum of the zirconia-supported single-site zinc catalyst does not have Zn-O-Zn bonds in the second shell compared to standard zinc oxide, and the R space of the X-ray absorption spectrum of the zirconia-supported single-site zinc catalyst does not have Zn-Zn bonds compared to standard zinc.

[0075] The above Figure 2 and Figure 3 The results show that the preparation method used in Example 1 can effectively synthesize zirconium oxide-supported single-point zinc catalyst.

[0076] Figure 4The X-ray absorption fine structure spectrum of the zirconium oxide-supported single-site zinc catalyst prepared in Example 1 shows that the single-site zinc is a zinc ion with a valence state of 0 < chemical valence < 2.

[0077] The catalytic performance of the prepared zirconia support and zirconia-supported zinc catalyst was tested.

[0078] The hydrogenation test was conducted on a flow-through fixed-bed reactor. Specifically, 300 mg of zirconia-supported zinc catalyst was diluted with 700 mg of SiC to reduce the influence of thermal effects. The diluted catalyst was placed in a quartz tube with an inner diameter of 5 mm, and the quartz tube was placed on the flow-through fixed-bed reactor. The reaction atmosphere was a mixture of carbon dioxide and hydrogen (gas volume ratio of 1:3), at a pressure of 3 MPa, and at a reaction temperature of 250℃~300℃.

[0079] The composition of the reaction products was detected in real time by online gas chromatography, and their specific catalytic activity per unit point of zinc supported on zirconium oxide was as follows: Figure 5 As shown.

[0080] from Figure 5 As can be seen, when the space velocity is 6000 mL / g cat At 250℃, the carbon dioxide conversion rate was 0.6% and the methanol selectivity was 98.5%; when the temperature was increased to 275℃, the carbon dioxide conversion rate was 1.6% and the methanol selectivity was 97.1%; when the temperature was further increased to 300℃, the carbon dioxide conversion rate was 4.6% and the methanol selectivity was 78.1%, at which point the methanol space-time yield (STY) was 1001.7 mmol / h. MeOH h -1 g Zn -1 As can be seen, under the same conditions, the carbon dioxide conversion rate and methanol selectivity of the zirconium oxide support are extremely low, with almost no activity.

[0081] from Figure 5 It can also be seen that the zirconia-supported single-site zinc catalyst described in this invention exhibits significantly higher reactivity than the ordinary zinc-zirconia composite metal oxide catalyst in Comparative Example 1. This indicates that the zirconia-supported single-site zinc catalyst formed by introducing single-site zinc atoms into the zirconia support can significantly enhance the catalytic activity of carbon dioxide hydrogenation to methanol.

[0082] Example 2

[0083] Weigh 10g of zirconium nitrate and dissolve it in deionized water. Stir in an oil bath at 70℃ and add ammonia precipitant at a uniform rate until the pH reaches 7. After centrifugation and washing, dry at 80℃ for 16h and place in a muffle furnace to calcine at 500℃ for 3h at a heating rate of 5℃ / min. After cooling to room temperature, grind the obtained zirconium oxide support into powder for later use.

[0084] Weigh 1.0 g of zinc nitrate and dissolve it in 100 mL of deionized water to prepare a metal salt solution. Slowly add ammonia water while stirring at a constant speed until the pH equals 9 to obtain the precursor solution.

[0085] Weigh 3.9g of zirconium oxide support and slowly add it to the precursor solution. Stir continuously at room temperature for three hours, filter and wash repeatedly three times, and dry at 60 degrees Celsius for 12 hours to obtain the calcined precursor.

[0086] The calcined precursor was placed in a muffle furnace and heated to 500°C in air at a heating rate of 5°C / min. After holding at this temperature for 3 hours, it was naturally cooled to obtain a zirconia-supported single-point zinc catalyst with a single-point zinc loading of 4.13 wt%.

[0087] The final zirconium oxide-supported zinc catalyst was analyzed by X-ray diffraction, and the results are as follows: Figure 6 As shown, the X-ray diffraction pattern of the catalyst is similar to that of standard monoclinic zirconium oxide. Figure 1 No other XRD diffraction peaks related to zinc were observed, in conjunction with Example 1. Figure 2 and Figure 3 This indicates that a zirconium oxide-supported single-point zinc catalyst was prepared in Example 2.

[0088] The catalytic performance of the prepared zirconia support and the zirconia-supported zinc-on-zirconia catalyst was tested.

[0089] Hydrogenation tests were conducted on a flow-through fixed-bed reactor. Specifically, 300 mg of catalyst was diluted with 700 mg of SiC and placed in a quartz tube with an inner diameter of 5 mm. The quartz tube was then placed on the flow-through fixed-bed reactor. The reaction atmosphere was a mixture of carbon dioxide and hydrogen (gas ratio 1:3), at a pressure of 3 MPa, and at a temperature of 300 °C. The composition of the reaction products was detected in real time by online gas chromatography, and their specific catalytic activity was as follows: Figure 7 As shown. From Figure 7 As can be seen, when the space velocity is 6000 mL / g cat At a temperature of 300℃, the carbon dioxide conversion rate was 1.5% and the methanol selectivity was 66.1%, which is significantly better than the activity of the zirconium oxide support itself.

[0090] Example 3

[0091] Weigh 10g of zirconium nitrate and dissolve it in deionized water. Stir in an oil bath at 70℃ and add ammonia precipitant at a uniform rate until the pH reaches 7. After centrifugation and washing, dry at 80℃ for 16h and place in a muffle furnace to calcine at 500℃ for 3h at a heating rate of 5℃ / min. After cooling to room temperature, grind the obtained zirconium oxide support into powder for later use.

[0092] Weigh 1.0 g of zinc nitrate and dissolve it in 100 mL of deionized water to prepare a metal salt solution. Slowly add ammonia water while stirring at a constant speed until the pH reaches 11.5 to obtain the precursor solution.

[0093] Weigh 3.9g of zirconium oxide support and slowly add it to the precursor solution. Stir continuously at room temperature for three hours, filter and wash repeatedly three times, and dry at 60 degrees Celsius for 12 hours to obtain the calcined precursor.

[0094] The calcined precursor was placed in a muffle furnace and heated to 500°C in air at a heating rate of 5°C / min. After being held at this temperature for 3 hours, it was naturally cooled to obtain a zirconia-supported single-point zinc catalyst with a single-point zinc loading of 0.81 wt%.

[0095] The final zirconium oxide-supported zinc catalyst was analyzed by X-ray diffraction, and the results are as follows: Figure 8 As shown, the X-ray diffraction pattern of the catalyst is similar to that of standard monoclinic zirconium oxide. Figure 1 No other XRD diffraction peaks related to zinc were observed, in conjunction with Example 1. Figure 2 and Figure 3 This indicates that Example 3 successfully prepared a zirconium oxide-supported zinc catalyst with a single point of contact.

[0096] The catalytic performance of the prepared zirconia support and the zirconia-supported zinc catalyst was tested.

[0097] The hydrogenation test was conducted on a flow-through fixed-bed reactor. Specifically, 300 mg of catalyst was diluted with 700 mg of SiC and placed in a quartz tube with an inner diameter of 5 mm. The quartz tube was then placed on the flow-through fixed-bed reactor.

[0098] The reaction atmosphere was a mixture of carbon dioxide and hydrogen (gas ratio 1:3), at a pressure of 3 MPa, and at a temperature of 300℃. The composition of the reaction products was detected in real time by online gas chromatography, and their specific catalytic activity was as follows: Figure 9 As shown. From Figure 9 As can be seen, when the space velocity is 6000 mL / g cat At a temperature of 300℃, the carbon dioxide conversion rate was 3.3% and the methanol selectivity was 71.2%, which were significantly better than the activity of the zirconium oxide support itself.

[0099] Example 4

[0100] Weigh 10g of zirconium nitrate and dissolve it in deionized water. Stir in an oil bath at 70℃ and add ammonia precipitant at a uniform rate until the pH reaches 7. After centrifugation and washing, dry at 80℃ for 16h and place in a muffle furnace to calcine at 500℃ for 3h at a heating rate of 5℃ / min. After cooling to room temperature, grind the obtained zirconium oxide support into powder for later use.

[0101] Weigh 0.5 g of zinc nitrate and dissolve it in 100 mL of deionized water to prepare a metal salt solution. Slowly add ammonia water while stirring at a constant speed until the pH equals 10 to obtain the precursor solution.

[0102] Weigh 3.9g of zirconium oxide support and slowly add it to the precursor solution. Stir continuously at room temperature for three hours, filter and wash repeatedly three times, and dry at 60 degrees Celsius for 12 hours to obtain the calcined precursor.

[0103] The calcined precursor was placed in a muffle furnace and heated to 500°C in air at a heating rate of 5°C / min. After holding at this temperature for 3 hours, it was naturally cooled to obtain a zirconia-supported single-point zinc catalyst with a single-point zinc loading of 2.77 wt%.

[0104] The final zirconium oxide-supported zinc catalyst was analyzed by X-ray diffraction, and the results are as follows: Figure 10 As shown, the results indicate that the X-ray diffraction pattern of the zirconia-supported single-site zinc catalyst is similar to that of the standard monoclinic zirconia. Figure 1 No other XRD diffraction peaks related to zinc were observed, in conjunction with Example 1. Figure 2 and Figure 3 This indicates that a zirconium oxide-supported single-point zinc catalyst was prepared in Example 4.

[0105] The catalytic performance of the prepared zirconia support and the zirconia-supported zinc catalyst was tested.

[0106] Hydrogenation tests were conducted on a flow-through fixed-bed reactor. Specifically, 300 mg of catalyst was diluted with 700 mg of SiC and placed in a quartz tube with an inner diameter of 5 mm. The quartz tube was then placed on the flow-through fixed-bed reactor. The reaction atmosphere was a mixture of carbon dioxide and hydrogen (gas ratio 1:3), at a pressure of 3 MPa, and at a temperature of 250℃–300℃. The composition of the reaction products was detected in real time by online gas chromatography, and their specific catalytic activity was as follows: Figure 11 As shown. From Figure 11 As can be seen, at a temperature of 300℃, the carbon dioxide conversion rate is 3.0% and the methanol selectivity is 60.8%, which is significantly better than the activity of the zirconium oxide support itself.

[0107] Example 5

[0108] Weigh 10g of zirconium nitrate and dissolve it in deionized water. Stir in an oil bath at 70℃ and add ammonia precipitant at a uniform rate until the pH reaches 7. After centrifugation and washing, dry at 80℃ for 16h and place in a muffle furnace to calcine at 500℃ for 3h at a heating rate of 5℃ / min. After cooling to room temperature, grind the obtained zirconium oxide support into powder for later use.

[0109] Weigh 1.9 g of zinc nitrate and dissolve it in 100 mL of deionized water to prepare a metal salt solution. Slowly add ammonia water while stirring at a constant speed until the pH equals 10 to obtain the precursor solution.

[0110] Weigh 3.9g of zirconium oxide support and slowly add it to the precursor solution. Stir continuously at room temperature for three hours, filter and wash repeatedly three times, and dry at 60 degrees Celsius for 12 hours to obtain the calcined precursor.

[0111] The calcined precursor was placed in a muffle furnace and heated to 500°C in air at a heating rate of 5°C / min. After being held at this temperature for 3 hours, it was naturally cooled to obtain a zirconia-supported single-point zinc catalyst with a single-point zinc loading of 0.81 wt%.

[0112] The final zirconium oxide-supported zinc catalyst was analyzed by X-ray diffraction, and the results are as follows: Figure 12 As shown, the results indicate that the X-ray diffraction pattern of the zirconia-supported single-site zinc catalyst is similar to that of the standard monoclinic zirconia. Figure 1 No other XRD diffraction peaks related to zinc were observed, in conjunction with Example 1. Figure 2 and Figure 3 This indicates that Example 5 yielded a zirconium oxide-supported, single-site zinc catalyst.

[0113] The catalytic performance of the prepared zirconia support and the zirconia-supported zinc catalyst was tested.

[0114] Hydrogenation tests were conducted on a flow-through fixed-bed reactor. Specifically, 300 mg of catalyst was diluted with 700 mg of SiC and placed in a quartz tube with an inner diameter of 5 mm. The quartz tube was then placed on the flow-through fixed-bed reactor. The reaction atmosphere was a mixture of carbon dioxide and hydrogen (gas ratio 1:3), at a pressure of 3 MPa, and at a temperature of 300 °C. The composition of the reaction products was detected in real time by online gas chromatography, and their specific catalytic activity was as follows: Figure 13 As shown. From Figure 13 As can be seen, at a temperature of 300℃, the carbon dioxide conversion rate is 3.2% and the methanol selectivity is 66.8%, which are significantly better than the activity of the zirconium oxide support itself.

[0115] Example 6

[0116] Weigh 10g of zirconium nitrate and dissolve it in deionized water. Stir in an oil bath at 70℃ and add ammonia precipitant at a uniform rate until the pH reaches 7. After centrifugation and washing, dry at 80℃ for 16h and place in a muffle furnace to calcine at 500℃ for 3h at a heating rate of 5℃ / min. After cooling to room temperature, grind the obtained zirconium oxide support into powder for later use.

[0117] Weigh 4.8g of zinc nitrate and dissolve it in 100mL of deionized water to prepare a metal salt solution. Slowly add ammonia water while stirring at a constant speed until the pH equals 10 to obtain the precursor solution.

[0118] Weigh 3.9g of zirconium oxide support and slowly add it to the precursor solution. Stir continuously at room temperature for three hours, filter and wash repeatedly three times, and dry at 60 degrees Celsius for 12 hours to obtain the calcined precursor.

[0119] The calcined precursor was placed in a muffle furnace and heated to 500°C in air at a heating rate of 5°C / min. After holding at this temperature for 3 hours, it was naturally cooled to obtain a zirconia-supported single-point zinc catalyst with a single-point zinc loading of 0.86 wt%.

[0120] The final zirconium oxide-supported zinc catalyst was analyzed by X-ray diffraction, and the results are as follows: Figure 14 As shown, the results indicate that the X-ray diffraction pattern of the zirconia-supported single-site zinc catalyst is similar to that of the standard monoclinic zirconia. Figure 1 No other XRD diffraction peaks related to zinc were observed, in conjunction with Example 1. Figure 2 and Figure 3 This indicates that a zirconium oxide-supported single-point zinc catalyst was prepared in Example 6.

[0121] The catalytic performance of the prepared zirconia support and the zirconia-supported zinc catalyst was tested.

[0122] Hydrogenation tests were conducted on a flow-through fixed-bed reactor. Specifically, 300 mg of catalyst was diluted with 700 mg of SiC and placed in a quartz tube with an inner diameter of 5 mm. The quartz tube was then placed on the flow-through fixed-bed reactor. The reaction atmosphere was a mixture of carbon dioxide and hydrogen (gas ratio 1:3), at a pressure of 3 MPa, and at a temperature of 300 °C. The composition of the reaction products was detected in real time by online gas chromatography, and their specific catalytic activity was as follows: Figure 15 As shown. From Figure 15 As can be seen, at a temperature of 300℃, the carbon dioxide conversion rate is 3.1% and the methanol selectivity is 72.7%, which is significantly better than the activity of the zirconium oxide support itself.

[0123] Comparative Example 1

[0124] Weigh out 5.3 g of zirconium nitrate and 0.9 g of zinc nitrate and dissolve them in 100 mL of deionized water to prepare a mixed metal salt solution. Add ammonium carbonate solution to the mixed metal salt solution at a uniform rate, stir at 70 °C for 4 h, and then filter and wash three times to obtain the calcination precursor.

[0125] The calcined precursor was placed in a muffle furnace and heated to 500°C at a heating rate of 5°C / min under an air atmosphere. After holding at this temperature for 3 hours, it was naturally cooled to obtain the zinc-zirconium composite metal oxide catalyst ZnO-ZrO2.

[0126] The catalytic activity and methanol selectivity of the zinc-zirconium composite metal oxide catalyst ZnO-ZrO2 for the hydrogenation of carbon dioxide are as follows: Figure 5 As shown in the figure. The results indicate that the highly efficient catalyst for the hydrogenation of carbon dioxide to methanol described in this invention exhibits excellent catalytic activity and methanol selectivity.

[0127] In summary, the zirconia-supported zinc catalysts prepared in Examples 1-6 of this invention not only have the advantages of high activity and high selectivity, but also have simple preparation methods and low preparation costs, and can exhibit very high catalytic performance in the reaction of carbon dioxide hydrogenation to methanol.

[0128] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A highly efficient catalyst for the hydrogenation of carbon dioxide to methanol, characterized in that, It consists of a zirconia support and unit zinc dots loaded on the surface of the zirconia support; The zirconium oxide support and the unit zinc spot are connected by Zn-O-Zr coordination bonds; The unit point zinc refers to zinc ions with a valence state of 0 < chemical valence < 2; The unit point zinc refers to zinc ions that contain only Zn-O-Zr and have no Zn-O-Zn or Zn-Zn coordination environment; The preparation method of the highly efficient catalyst for the hydrogenation of carbon dioxide to methanol includes the following steps: 1) A zirconium salt solution is mixed with a precipitant and subjected to a constant-temperature precipitation reaction to obtain a zirconium oxide precursor, which is then heat-treated to prepare a zirconium oxide support. 2) Add ammonia to the zinc salt solution and adjust the pH until the precipitate formed in the solution is completely dissolved to obtain a solution of tetraamminezinc hydroxide; 3) The zirconium oxide support obtained in step 1) is mixed with the solution of tetraamminezinc hydroxide obtained in step 2) and then dried to obtain the catalyst precursor; 4) The catalyst precursor obtained in step 3) is calcined to obtain a highly efficient catalyst for the hydrogenation of carbon dioxide to methanol.

2. The highly efficient catalyst for the hydrogenation of carbon dioxide to methanol according to claim 1, characterized in that, The zinc loading per unit point is 0.07wt%~6wt%.

3. A method for preparing a highly efficient catalytic catalyst for the hydrogenation of carbon dioxide to methanol as described in any one of claims 1 to 2, characterized in that, Includes the following steps: 1) A zirconium salt solution is mixed with a precipitant and subjected to a constant-temperature precipitation reaction to obtain a zirconium oxide precursor, which is then heat-treated to prepare a zirconium oxide support. 2) Add ammonia to the zinc salt solution and adjust the pH until the precipitate formed in the solution is completely dissolved to obtain a solution of tetraamminezinc hydroxide; 3) The zirconium oxide support obtained in step 1) is mixed with the solution of tetraamminezinc hydroxide obtained in step 2) and then dried to obtain the catalyst precursor; 4) The catalyst precursor obtained in step 3) is calcined to obtain a highly efficient catalyst for the hydrogenation of carbon dioxide to methanol.

4. The preparation method according to claim 3, characterized in that, The zirconium salt solution in step 1) is selected from one or more of zirconium nitrate solution, zirconium chloride solution, zirconium oxychloride solution, and zirconium sulfate solution.

5. The preparation method according to claim 3, characterized in that, The precipitant in step 1) is selected from one or more of ammonium carbonate, ammonia, and sodium carbonate.

6. The preparation method according to claim 3, characterized in that, The temperature of the isothermal precipitation reaction in step 1) is 30℃~100℃; The time for the isothermal precipitation reaction is selected from 1 to 48 hours.

7. The preparation method according to claim 3, characterized in that, The zinc salt solution in step 2) is selected from one or more of zinc nitrate solution, zinc chloride solution, zinc sulfate solution, and zinc acetate solution; The pH in step 2) is selected from 9 to 12.

8. The preparation method according to claim 3, characterized in that, The calcination temperature in step 4) is 300℃~700℃; The calcination time is 1-5 h; The heating rate of the calcination is 2~10℃ / min.

9. A method for producing methanol by hydrogenation of carbon dioxide, characterized in that, The process involves using the highly efficient catalytic carbon dioxide hydrogenation to methanol catalyst as described in any one of claims 1 to 2, or the highly efficient catalytic carbon dioxide hydrogenation to methanol catalyst prepared by the preparation method described in any one of claims 3 to 8, to perform carbon dioxide hydrogenation to methanol.

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