CuZnAlZr and carbon material composite catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of catalysts, and particularly relates to a CuZnAlZr and carbon material composite catalyst as well as a preparation method and application thereof. The composite catalyst is composed of a metal component and a carbon nanotube; and the metal components comprise CuO, ZnO, Al2O3 and ZrO2, or comprise CuO, ZnO, Al2O3 and ZrO2, or comprise CuO, ZnO, Al2O3 and ZrO2. The preparation method of the composite catalyst comprises the following steps: preparing a CuZnAlZr salt mixed solution, preparing a precipitant mixed solution, preparing a carbon nanotube mixed solution, mixing, aging, washing, drying, roasting, granulating and the like. The obtained composite catalyst can be used for catalyzing carbon dioxide hydrogenation to prepare methanol, the catalytic activity of the composite catalyst is high, when the composite catalyst is used for catalyzing carbon dioxide hydrogenation to prepare methanol, the CO2 conversion rate is high, the methanol selectivity is high, the methanol space time yield is high, and the excellent catalytic activity is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and particularly relates to a CuZnAlZr and carbon material composite catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] The main anthropogenic factor of global warming is the continuous increase in the concentration of carbon dioxide in the atmosphere. One of the most effective and economical methods for the conversion and utilization of carbon dioxide is the catalytic hydrogenation of carbon dioxide to methanol. Thermal catalysis dominates in industry, and the research on catalysts is the key.

[0003] Copper-based catalysts are widely used in the hydrogenation of carbon dioxide to methanol. The preparation methods include co-precipitation method, impregnation method, sol-gel method, etc., among which the co-precipitation method is the most widely used. The selected promoters generally include Zn, Al, Zr, Ce, In, etc., which can adjust the surface properties of the catalyst, change the structure, and form an interaction with the active component, thereby improving the activity of the catalyst.

[0004] Currently, the traditional catalyst for the synthesis of methanol from industrial syngas is Cu-ZnO-Al 2 O 3 , however, copper-based catalysts have disadvantages such as low efficiency, easy sintering and deactivation, and poor stability, and water will be produced during the formation of methanol, which will affect the reaction and reduce the selectivity of methanol. These disadvantages limit their potential in large-scale industrial applications.

[0005] Patent application CN101786001A discloses a catalyst for the hydrogenation of carbon dioxide to methanol, but this catalyst has the problem of low CO2 conversion rate.

[0006] Patent application CN107008332B discloses a catalyst for the hydrogenation of carbon dioxide to synthesize methanol, but this catalyst has the problem of poor methanol selectivity.

[0007] Therefore, there is still an urgent need for a catalyst for the hydrogenation of carbon dioxide to synthesize methanol with high CO 2 conversion rate and high methanol selectivity. Summary of the Invention

[0008] To solve the above technical problems, the present invention provides the following technical solutions.

[0009] In the first aspect, the present invention provides a composite catalyst.

[0010] A composite catalyst, the composition of the composite catalyst is a metal component and carbon nanotubes; the metal component is CuO, ZnO and Al 2 O 3 , or is CuO, ZnO, Al 2 O3 and ZrO 2 ; Among them, the molar ratio of Cu, Zn, Al, and Zr in the composite catalyst is 2:1:x:z; x is 0.1 - 1, and the sum of z and x is 1, The mass ratio of carbon nanotubes to the total mass of CuO, ZnO, Al 2 O 3 and ZrO 2 is 16.6:100 - 19.7:100.

[0011] In some preferred embodiments, the molar ratio of Cu, Zn, Al, and Zr in the composite catalyst is 2:1:0.6:0.4, 2:1:0.7:0.3, or 2:1:0.8:0.2.

[0012] In some embodiments, the mass ratio of carbon nanotubes to the total mass of CuO, ZnO, Al 2 O 3 and ZrO 2 is 16.6:100, 17.0:100, 17.5:100, 17.8:100, 18.0:100, 18.5:100, 18.7:100, 19.0:100, 19.5:100, or 19.7:100. In some preferred embodiments, the mass ratio of carbon nanotubes to the total mass of CuO, ZnO, Al 2 O 3 and ZrO 2 is 18.7:100.

[0013] In some embodiments, the carbon nanotubes are multi-walled carbon nanotubes.

[0014] In some embodiments, the composite catalyst is prepared according to the preparation method described in the second aspect.

[0015] Second aspect, the present invention provides a preparation method of a composite catalyst.

[0016] A preparation method of a composite catalyst, which includes the following steps: (1) Preparation of CuZnAlZr salt mixture: Dissolve water-soluble copper salt, water-soluble zinc salt, water-soluble aluminum salt, and water-soluble zirconium salt in water to obtain a CuZnAlZr salt mixture; (2) Preparation of precipitant mixture: Mix the precipitant with water to obtain a precipitant mixture; (3) Preparation of carbon nanotube mixture: Mix carbon nanotubes with water to obtain a carbon nanotube mixture; (4) Mixing and aging: Add the CuZnAlZr salt mixture and the precipitant mixture to the carbon nanotube mixture while mixing, and control the pH to be 9.0 - 11.0 during the mixing process; after the addition is completed, obtain the mixed solution 1, and age the mixed solution 1 to obtain the mixed solution 2; (5) Washing, drying, calcining, and granulating: Wash the mixed solution 2 obtained in step (4) with water until neutral, dry, calcine, and granulate to obtain the composite catalyst.

[0017] In some embodiments, the CuZnAlZr salt mixture and the precipitant mixture in step (4) are added to the carbon nanotube mixture in a co-current dropwise manner.

[0018] In some preferred embodiments, the pH in step (4) is preferably 9.8 - 10.2. In some more preferred embodiments, the pH in step (4) is preferably 10.0.

[0019] In some embodiments, the pH control during the mixing process in step (4) is achieved by adjusting the dropping rate of the CuZnAlZr salt mixture and / or the precipitant mixture.

[0020] In some embodiments, the water-soluble copper salt is selected from at least one of Cu(NO 3 ) 2 or its hydrate, copper sulfate or its hydrate, copper chloride or its hydrate.

[0021] In some embodiments, the water-soluble zinc salt is selected from at least one of Zn(NO 3 ) 2 or its hydrate, zinc sulfate or its hydrate, zinc chloride or its hydrate.

[0022] In some embodiments, the water-soluble aluminum salt is selected from at least one of Al(NO 3 ) 3 or its hydrate, aluminum sulfate or its hydrate, aluminum chloride or its hydrate.

[0023] In some embodiments, the water-soluble zirconium salt is selected from at least one of Zr(NO 3 ) 4 or its hydrate, zirconium oxychloride or its hydrate, zirconium chloride or its hydrate.

[0024] In some embodiments, the precipitant includes at least one of NaOH, Na 2 CO 3 , ammonia water, urea, potassium hydroxide.

[0025] In some preferred embodiments, the water-soluble copper salt is selected from Cu(NO 3) 2 ·3H 2 O。

[0026] In some preferred embodiments, the water-soluble zinc salt is selected from Zn(NO 3 ) 2 ·6H 2 O。

[0027] In some preferred embodiments, the water-soluble aluminum salt is selected from Al(NO 3 ) 3 ·9H 2 O。

[0028] In some preferred embodiments, the water-soluble zirconium salt is selected from Zr(NO 3 ) 4 ·5H 2 O。

[0029] In some preferred embodiments, the precipitating agent includes NaOH and Na 2 CO 3 。

[0030] In some embodiments, in the CuZnAlZr salt mixture solution in step (4), the molar feed amounts of Cu 2+ , Zn 2+ , Al 3+ and Zr 4+ are in a ratio of 2:1:x:z, where x is 0.1 - 1 and the sum of z and x is 1. In some preferred embodiments, in the CuZnAlZr salt mixture solution in step (4), the molar feed amounts of Cu 2+ , Zn 2+ , Al 3+ and Zr 4+ are in a ratio of 2:1:x:z, where x is 0.6 - 0.8 and the sum of z and x is 1. In some preferred embodiments, in the CuZnAlZr salt mixture solution in step (4), the molar feed amounts of Cu 2+ , Zn 2+ , Al 3+ and Zr 4+ are in a ratio of 2:1:0.6:0.4, 2:1:0.7:0.3 or 2:1:0.8:0.2.

[0031] In some embodiments, the precipitating agent includes NaOH and Na 2 CO 3 , and in the precipitating agent solution in step (4), the molar feed amount of NaOH is related to Cu 2+ , Zn 2+ , Al 3+ and Zr4+ The molar ratio of the total feed is 1:1 - 3:1, preferably 1.5:1; the molar amount of Na 2 CO 3 fed in the precipitant solution and the molar amount of Al 3+ fed in the CuZnAlZr salt mixture solution is 1:1 - 3:1 or 2:1.

[0032] In some embodiments, the molar concentration ratio of Cu 2+ :Zn 2+ :Al 3+ :Zr 4+ in the CuZnAlZr salt mixture solution is 2:1:x:z, where x is 0.1 - 1 and the sum of z and x is 1. In some preferred embodiments, the molar concentration ratio of Cu 2+ , Zn 2+ , Al 3+ and Zr 4+ in the CuZnAlZr salt mixture solution in step (4) is 2:1:x:z, where x is 0.6 - 0.8 and the sum of z and x is 1. In some preferred embodiments, the molar concentration ratio of Cu 2+ :Zn 2+ :Al 3+ :Zr 4+ is 2:1:0.6:0.4, 2:1:0.7:0.3 or 2:1:0.8:0.2.

[0033] In some embodiments, the precipitant includes NaOH and Na 2 CO 3 , the molar concentration of NaOH in the precipitant solution is 1 - 3 times (such as 1, 1.5, 2, 2.5 or 3 times) or 1.5 times the total molar concentration of Cu 2+ , Zn 2+ , Al 3+ and Zr 4+ in the CuZnAlZr salt mixture solution, and the molar concentration of Na 2 CO 3 in the precipitant solution is 1 - 3 times (such as 1, 1.5, 2, 2.5 or 3 times) or 2 times the molar concentration of Al 3+ in the CuZnAlZr salt mixture solution.

[0034] In some embodiments, the feeding volume ratio of the CuZnAlZr salt mixture solution and the precipitant mixture solution in step (4) is 1:1 - 3:1. In some embodiments, the feeding volume ratio of the CuZnAlZr salt mixture solution and the precipitant mixture solution in step (4) is 1:1, 2:1 or 3:1.

[0035] In some embodiments, the ratio of the feeding mass of carbon nanotubes in the carbon nanotube mixture in step (4) to the total feeding mass of water-soluble copper salt, water-soluble zinc salt, water-soluble aluminum salt and water-soluble zirconium salt in the CuZnAlZr salt mixture is 1-10:100. In some preferred embodiments, the ratio of the feeding mass of carbon nanotubes in the carbon nanotube mixture in step (4) to the total feeding mass of water-soluble copper salt, water-soluble zinc salt, water-soluble aluminum salt and water-soluble zirconium salt in the CuZnAlZr salt mixture is 4:100-6:100. In some more preferred embodiments, the ratio of the feeding mass of carbon nanotubes in the carbon nanotube mixture in step (4) to the total feeding mass of water-soluble copper salt, water-soluble zinc salt, water-soluble aluminum salt and water-soluble zirconium salt in the CuZnAlZr salt mixture is 5:100.

[0036] In some embodiments, Cu in the CuZnAlZr salt mixture 2+ :Zn 2+ :Al 3+ :Zr 4+ The total molar concentration is 1 mol / L - 3 mol / L. In some embodiments, Cu in the CuZnAlZr salt mixture 2+ :Zn 2+ :Al 3+ :Zr 4+ The total molar concentration is 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L or 3 mol / L.

[0037] In some embodiments, the precipitant includes NaOH and Na 2 CO 3 , the molar concentration of NaOH in the precipitant mixture is 1.5 mol / L - 4.5 mol / L (such as 1.5 mol / L, 2.0 mol / L, 2.5 mol / L, 3.0 mol / L, 3.5 mol / L, 4.0 mol / L or 4.5 mol / L) or 1.5 mol / L; the molar concentration of Na 2 CO 3 in the precipitant mixture is 1-3 times (such as 1, 1.5, 2, 2.5 or 3 times) or 2 times the molar concentration of Al 3+ in the CuZnAlZr salt mixture.

[0038] In some embodiments, the precipitant includes NaOH and Na 2 CO 3 , the molar concentration of NaOH in the precipitant mixture is 1.5 mol / L; the molar concentration of Na in the precipitant mixture2 CO 3 The molar concentration of is twice the molar concentration of Al in the CuZnAlZr salt mixture solution. 3+

[0039] In some embodiments, the aging is to stir the mixed solution 1 at 50°C - 80°C. In some embodiments, the aging is to stir the mixed solution 1 at 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C.

[0040] In some embodiments, the aging time is 8 hours - 16 hours. In some embodiments, the aging time is 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours or 16 hours. In some preferred embodiments, the aging time is 15 hours.

[0041] In some embodiments, the neutrality in step (5) means the pH is 6 - 8. In some embodiments, the neutrality in step (5) means the pH is 6, 6.8, 7, 7.2 or 8.

[0042] In some embodiments, the drying in step (5) is carried out at 60°C - 110°C. In some embodiments, the drying in step (5) is carried out at 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C or 110°C.

[0043] In some embodiments, the drying time of the drying in step (5) is 10 hours - 16 hours. In some embodiments, the drying time of the drying in step (5) is 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours or 16 hours.

[0044] In some embodiments, the calcination in step (5) is carried out under a nitrogen atmosphere or an inert gas atmosphere.

[0045] In some embodiments, the temperature of the calcination in step (5) is 400°C - 600°C. In some embodiments, the temperature of the calcination in step (5) is 400°C, 450°C, 500°C, 550°C or 600°C.

[0046] In some embodiments, the time of the calcination in step (5) is 3 hours - 6 hours. In some embodiments, the time of the calcination in step (5) is 3 hours, 4 hours, 5 hours or 6 hours.

[0047] ​In some embodiments, the granulation in step (5) is to form the solid obtained by roasting into particles with a particle size in the range of 0.450 mm - 0.900 mm. In some embodiments, the granulation in step (5) is to form the solid obtained by roasting into particles with a particle size of 0.450 mm, 0.500 mm, 0.600 mm, 0.700 mm, 0.800 mm or 0.900 mm.

[0048] In some embodiments, the granulation includes a compression granulation method.

[0049] In some embodiments, the carbon nanotubes are multi-walled carbon nanotubes.

[0050] In a third aspect, the present invention provides a composite catalyst.

[0051] A composite catalyst prepared by the preparation method described in the second aspect.

[0052] In a fourth aspect, the present invention provides an application of the aforementioned composite catalyst.

[0053] An application of the composite catalyst described in the first aspect, the composite catalyst prepared by the preparation method described in the second aspect, or the composite catalyst described in the third aspect in the catalytic hydrogenation of carbon dioxide to produce methanol.

[0054] Beneficial effects Compared with the prior art, at least one of the following beneficial technical effects is included in a certain embodiment of the present invention: (1) The composite catalyst obtained by the present invention has unexpectedly excellent catalytic activity for the reaction of hydrogenating CO 2 to produce methanol, has excellent CO 2 conversion rate, methanol selectivity and methanol space-time yield, and has excellent unexpected technical effects.

[0055] (2) As can be seen from the results in Table 4, compared with other molar ratios of Cu 2+ :Zn 2+ :Al 3+ :Zr 4+ in the CuZnAlZr salt mixture solution (such as 2:1:1:0, 2:1:0.9:0.1, 2:1:0.5:0.5, 2:1:0.3:0.7), the composite catalyst obtained by using the CuZnAlZr salt mixture solution with other molar ratios of Cu 2+ :Zn 2+ :Al 3+ :Zr 4+ provided by the present invention (such as 2:1:0.7:0.3, 2:1:0.8:0.2 and 2:1:0.6:0.4) has a higher CO when catalyzing the reaction of hydrogenating CO2 to produce methanol.2 Conversion rate, higher methanol selectivity and methanol space-time yield, with excellent unexpected technical effects.

[0056] (3) Compared with the other ratios of the total mass of the carbon nanotubes fed in step (3) to Cu(NO 3 ) 2 ·3H 2 O, Zn(NO 3 ) 2 ·6H 2 O, Al(NO 3 ) 3 ·9H 2 O, Zr(NO 3 ) 4 ·5H 2 O (such as less than or equal to 1:99, or greater than or equal to 10:90), using the ratio of the mass of the carbon nanotubes fed in step (3) provided by the present invention to Cu(NO 3 ) 2 ·3H 2 O, Zn(NO 3 ) 2 ·6H 2 O, Al(NO 3 ) 3 ·9H 2 O, Zr(NO 3 ) 4 ·5H 2 O (4:100 - 6:100) in the catalytic reaction of CO2 hydrogenation to methanol has higher CO 2 Conversion rate, higher methanol selectivity and methanol space-time yield, with excellent unexpected technical effects.

[0057] (4) Compared with other pH values (such as 6.0 ± 0.2, 7.0 ± 0.2, 12.0 ± 0.2) during the mixing process in step (4), using the pH value (such as 10.0 ± 0.2) during the mixing process in step (4) provided by the present invention in the catalytic reaction of CO2 hydrogenation to methanol has higher CO 2 Conversion rate, higher methanol selectivity and methanol space-time yield, with excellent unexpected technical effects.

[0058] Term definition: In the present invention, "room temperature" refers to the ambient temperature, which can be 20°C - 30°C; in some embodiments, it is 22°C - 28°C; in some embodiments, it is 24°C - 26°C; in some embodiments, it is 25°C.

[0059] In the foregoing of the present invention, all the numbers disclosed herein are approximate values, whether or not the words "about" or "approximately" are used. Based on the disclosed numbers, the numerical value of each number may have a difference of less than ±10% or a reasonable difference considered by those skilled in the art, such as a difference of ±1%, ±2%, ±3%, ±4% or ±5%.

[0060] The term "optionally", "optional" or "optionally" means that the subsequent described event or situation may but does not necessarily occur.

[0061] The term "wt%" represents weight percentage.

[0062] The term "GHSV" is an abbreviation of "Gas Hourly Space Velocity", which refers to the ratio of the volume flow rate of the gas entering the reactor to the volume of the catalyst per unit time.

[0063] The term "cocurrent dropwise addition" means adding two or more liquid reagents in a cocurrent manner, that is, keeping their flow directions consistent, and at the same time slowly adding them drop by drop into a reaction vessel or system. This operation requires the liquid to enter the target system drop by drop, in a controlled, slow and uniform manner, rather than being poured quickly or flowing in a stream.

[0064] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples. Description of the Drawings

[0065] Figure 1 XRD pattern of the composite catalyst obtained in Example 1.

[0066] Figure 2 SEM image of the composite catalyst obtained in Example 1.

[0067] Figure 3 TEM image of the composite catalyst obtained in Example 1.

[0068] Figure 4 Nitrogen adsorption - desorption isotherm of the composite catalyst obtained in Example 1. Detailed Description of the Invention

[0069] To enable those skilled in the art to better understand the technical solution of the present invention, some non-limiting embodiments are further disclosed below for a further detailed description of the present invention.

[0070] All the reagents used in the present invention can be purchased from the market or prepared by the methods described in the present invention.

[0071] Reagent sources: Copper nitrate trihydrate (Xilong Scientific, AR), Zinc nitrate hexahydrate (Xilong Scientific, AR), Aluminum nitrate nonahydrate (Sinopharm Chemical Reagent Co., Ltd., AR), Zirconium nitrate pentahydrate (Macklin, AR), Carbon nanotubes (manufacturer: Xianfeng Nano, type: multi-walled carbon nanotubes), Sodium hydroxide (Sinopharm Chemical Reagent Co., Ltd., AR), Sodium carbonate (Sinopharm Chemical Reagent Co., Ltd., AR).

[0072] Example 1: Preparation of composite catalyst The composite catalyst was prepared according to the following method: (1) Preparation of CuZnAlZr salt mixture solution: Dissolve Cu(NO 3 ) 2 ·3H 2 O, Zn(NO 3 ) 2 ·6H 2 O, Al(NO 3 ) 3 ·9H 2 O, Zr(NO 3 ) 4 ·5H 2 O in 50 ml of water to obtain a CuZnAlZr salt mixture solution; the molar ratio of Cu 2+ :Zn 2+ :Al 3+ :Zr 4+ in the CuZnAlZr salt mixture solution is 2:1:0.7:0.3, and the total molar concentration of Cu 2+ :Zn 2+ :Al 3+ :Zr 4+ in the CuZnAlZr salt mixture solution is 1 mol / L; (2) Preparation of precipitant mixture solution: Mix NaOH and Na 2 CO 3 with 50 ml of water to obtain a precipitant mixture solution; the molar concentration of NaOH in the precipitant mixture solution is 1.5 mol / L, and the molar concentration of Na 2 CO 3 is the same as that of Al 3+Twice the molar concentration; (3) Preparation of carbon nanotube mixture: Mix carbon nanotubes with 100 ml of water to obtain a carbon nanotube mixture; the mass of the carbon nanotubes fed is in a ratio of 5:100 to the total mass of Cu(NO 3 ) 2 ·3H 2 O, Zn(NO 3 ) 2 ·6H 2 O, Al(NO 3 ) 3 ·9H 2 O, Zr(NO 3 ) 4 ·5H 2 O; (4) Mixing and aging: Slowly add the CuZnAlZr salt mixture and the precipitant mixture drop by drop into the carbon nanotube mixture while mixing, controlling the pH to be 10.0 ± 0.2 during the mixing process (by adjusting the dropping rates of the CuZnAlZr salt mixture and / or the precipitant mixture to control the pH); after the addition, obtain mixture solution 1, and age mixture solution 1 by stirring at 60°C for 15 hours to obtain mixture solution 2; (5) Washing, drying, calcining and granulating: Wash the mixture solution 2 obtained in step (4) with water until neutral (pH 7.0 ± 0.2), dry at 80°C for 10 h, calcine in a nitrogen atmosphere at 500°C for 4 h, and granulate to 0.600 mm (it can be 0.450 mm - 0.900 mm) to obtain the composite catalyst.

[0073] Take the obtained composite catalyst for XRD (X-ray diffraction), nitrogen adsorption-desorption test, BET (specific surface area and porosity analysis), SEM (scanning electron microscope) and TEM (transmission electron microscope) detection.

[0074] Results: As Figure 1 shown by the XRD pattern, the composite catalyst obtained in Example 1 shows diffraction peaks of a typical hydrotalcite-like structure. The introduction of the carbon material does not affect the crystal phase of the hydrotalcite-like, and no diffraction peaks of carbon are detected, indicating that the introduced amount of carbon nanotubes is too small and it exists in an amorphous state.

[0075] As Figure 4 can be seen, the composite catalyst obtained in Example 1 forms a slit-shaped pore structure dominated by mesopores. The mesopore-dominated pore structure is beneficial to the diffusion of reactants and the exposure of active sites, which is beneficial to improving the activity of the obtained composite catalyst. And from the fact that the adsorption and desorption curves basically coincide, it can be known that the composite catalyst obtained in Example 1 of the present invention has structural stability.

[0076] The BET test results show that the specific surface area, pore volume, and pore diameter of the composite catalyst obtained in Example 1 are 63.57 m 2 / g, 0.54 cm 3 / g, and 16.94 nm, respectively.

[0077] For the SEM image of the composite catalyst obtained in Example 1, see Figure 2 , and for the TEM image of the obtained composite catalyst, see Figure 3 .

[0078] Examples 2 - 3: Preparation of the composite catalyst Example 2: Referring to the preparation method of Example 1, adjust the molar ratio of Cu 2+ :Zn 2 + :Al 3+ :Zr 4+ in the CuZnAlZr salt mixture solution in step (1) to 2:1:0.8:0.2, and keep the rest of the reagents, reagent dosages, operations, and operating conditions the same as in Example 1.

[0079] Example 3: Referring to the preparation method of Example 1, adjust the molar ratio of Cu 2+ :Zn 2 + :Al 3+ :Zr 4+ in the CuZnAlZr salt mixture solution in step (1) to 2:1:0.6:0.4, and keep the rest of the reagents, reagent dosages, operations, and operating conditions the same as in Example 1.

[0080] Example 4: Adjust the ratio of the feeding mass of the carbon nanotubes in step (3) to the total mass of Cu(NO 3 ) 2 ·3H 2 O, Zn(NO 3 ) 2 ·6H 2 O, Al(NO 3 ) 3 ·9H 2 O, Zr(NO 3 ) 4 ·5H 2 O to 4:100, and keep the rest of the reagents, reagent dosages, operations, and operating conditions the same as in Example 1.

[0081] Example 5: Adjust the ratio of the feeding mass of the carbon nanotubes in step (3) to the total mass of Cu(NO 3 ) 2 ·3H 2 O, Zn(NO 3 ) 2 ·6H2 O, Al(NO 3 ) 3 ·9H 2 O, Zr(NO 3 ) 4 ·5H 2 The ratio of the total mass of O to 6:100 was adjusted, and the other reagents, reagent feeding amounts, operations, and operating conditions were the same as those in Example 1.

[0082] Comparative Examples 1 - 4: The molar ratio of Cu 2+ :Zn 2+ :Al 3+ :Zr 4+ in the CuZnAlZr salt mixture was investigated For the molar ratio of Cu 2+ :Zn 2+ :Al 3+ :Zr 4+ in the CuZnAlZr salt mixture, the investigation ratios are shown in Table 1, and the other reagents, reagent feeding amounts, operations, and operating conditions were the same as those in Example 1.

[0083] Table 1: Investigation of the molar ratio of Cu 2+ :Zn 2+ :Al 3+ :Zr 4+ in the CuZnAlZr salt mixture Comparative Examples 5 - 8: Investigation of the mass ratio of carbon nanotubes to the precursor For the feeding mass of the carbon nanotubes described in step (3) and the total mass of Cu(NO 3 ) 2 ·3H 2 O, Zn(NO 3 ) 2 ·6H 2 O, Al(NO 3 ) 3 ·9H 2 O, Zr(NO 3 ) 4 ·5H 2 O (abbreviated as "mass ratio of carbon nanotubes to the precursor" in Table 1) was investigated, and the investigation ratios are shown in Table 2. The other reagents, reagent feeding amounts, operations, and operating conditions were the same as those in Example 1.

[0084] Table 2: Investigation of the mass ratio of carbon nanotubes to the precursor Comparative Examples 9 - 11: Investigation of the co - precipitation pH The pH during the mixing process in step (4) was investigated, and the investigated pH values are shown in Table 3. Other reagents, reagent dosages, operations, and operating conditions were the same as those in Example 1.

[0085] Table 3: Investigation of pH Test Example 1: Catalytic CO 2 Investigation of the reaction activity for the hydrogenation of CO to methanol Take the composite catalysts obtained in the above examples or comparative examples, and investigate the reaction activity of each catalyst for the hydrogenation of CO to methanol according to the following operations respectively. 2

[0086] Take 0.5 g of the composite catalyst to be tested and uniformly mix it with 1 g of quartz sand, and place it in a fixed-bed reactor for catalytic performance evaluation. The catalyst to be tested was first reduced with pure H at atmospheric pressure and 300 °C for 3 h before the reaction. After the reduction, the temperature was lowered to the reaction temperature (240 °C), and the reaction mixed gas [H 2 : CO 2 : 2 : N 2 = 69:23:8 (volume ratio)] was switched for the reaction. The reaction pressure was 5 Mpa, the reaction temperature was 240 °C, GHSV = 3600 ml / (h·g), and the substances coming out of the reaction tube were analyzed by gas chromatography. The results are shown in Table 4.

[0087] Table 4: Investigation results of the reaction activity for the hydrogenation of CO to methanol 2 Conclusion: (1) From the results in Table 4, it can be seen that compared with other molar ratios of Cu 2+ :Zn 2+ :Al 3+ :Zr 4+ in the CuZnAlZr salt mixture (such as 2:1:1:0 (Comparative Example 1), 2:1:0.9:0.1 (Comparative Example 2), 2:1:0.5:0.5 (Comparative Example 3), 2:1:0.3:0.7 (Comparative Example 4)), the composite catalysts obtained with other molar ratios of Cu 2+ :Zn 2+ :Al 3+ :Zr 4+ in the CuZnAlZr salt mixture provided by the present invention (such as 2:1:0.7:0.3 (Example 1), 2:1:0.8:0.2 (Example 2), and 2:1:0.6:0.4 (Example 3)) have higher CO 2 during the reaction for the hydrogenation of CO to methanol. 2Conversion rate, higher methanol selectivity and methanol space-time yield, with excellent unexpected technical effects.

[0088] (2) Compared with the other ratios of the feeding mass of carbon nanotubes to the total mass of Cu(NO 3 ) 2 ·3H 2 O, Zn(NO 3 ) 2 ·6H 2 O, Al(NO 3 ) 3 ·9H 2 O, Zr(NO 3 ) 4 ·5H 2 O (such as less than or equal to 1:99 (Comparative Example 5 - Comparative Example 6), or greater than or equal to 10:90 (Comparative Example 7 - Comparative Example 8)), using the ratio of the feeding mass of carbon nanotubes to the total mass of Cu(NO 3 ) 2 ·3H 2 O, Zn(NO 3 ) 2 ·6H 2 O, Al(NO 3 ) 3 ·9H 2 O, Zr(NO 3 ) 4 ·5H 2 O (4:100 - 6:100 (Example 1, Example 4, Example 5)) for the obtained composite catalyst in the reaction of catalytic hydrogenation of CO2 to methanol has higher CO 2 conversion rate, higher methanol selectivity and methanol space-time yield, with excellent unexpected technical effects.

[0089] (3) Compared with other pH values during the mixing process in step (4) (such as: 6.0 ± 0.2, 7.0 ± 0.2, 12.0 ± 0.2), using the pH value (such as 10.0 ± 0.2) during the mixing process in step (4) provided by the present invention for the obtained composite catalyst in the reaction of catalytic hydrogenation of CO 2 has higher CO 2 conversion rate, higher methanol selectivity and methanol space-time yield, with excellent unexpected technical effects.

[0090] The method of the present invention has been described by way of preferred embodiments. It is obvious that relevant personnel can make changes or appropriate modifications and combinations to the methods and applications described herein within the content, spirit and scope of the present invention to implement and apply the technology of the present invention. Those skilled in the art can draw on the content of this article and appropriately improve the process parameters to achieve it. It should be particularly pointed out that all such similar substitutions and modifications are obvious to those skilled in the art and are all considered to be included in the present invention.

Claims

1. A composite catalyst, characterized in that: The composite catalyst is composed of metal components and carbon nanotubes; the metal components are CuO, ZnO and Al2O3, or CuO, ZnO, Al2O3 and ZrO2; Wherein, the molar ratio of Cu, Zn, Al and Zr in the composite catalyst is 2:1:x:z; x is 0.1-1, the sum of z and x is 1, Preferably, the molar ratio of Cu, Zn, Al and Zr in the composite catalyst is 2:1:0.6:0.4, 2:1:0.7:0.3 or 2:1:0.8:0.2; The ratio of the mass of carbon nanotubes to the total mass of CuO, ZnO, Al2O3 and ZrO2 is 16.6:100-19.7:100, preferably 18.7:

100.

2. A method for preparing a composite catalyst, characterized in that: The following steps are involved: (1) Preparation of a CuZnAlZr salt mixture: dissolving a water-soluble copper salt, a water-soluble zinc salt, a water-soluble aluminum salt and a water-soluble zirconium salt in water to obtain a CuZnAlZr salt mixture; (2) Preparation of precipitant mixed solution: mixing the precipitant with water to obtain a precipitant mixed solution; (3) Preparation of a carbon nanotube mixed solution: mixing carbon nanotubes with water to obtain a carbon nanotube mixed solution; (4) Mixing and aging: adding the CuZnAlZr salt mixture and the precipitant mixture to the carbon nanotube mixture, mixing while adding, and controlling the pH value in the mixing process to be 9.0-11.0; After the addition is completed, a mixed solution 1 is obtained, and the mixed solution 1 is aged to obtain a mixed solution 2; (5) Washing, drying, calcining and granulating: The mixed solution 2 obtained in step (4) is washed with water until it becomes neutral, dried, calcined and granulated to obtain the composite catalyst.

3. The preparation method according to claim 2, wherein the CuZnAlZr salt mixed solution and the precipitant mixed solution in step (4) are added to the carbon nanotube mixed solution dropwise in parallel; The pH of step (4) is preferably 9.8-10.2, more preferably 10.0; The pH of the mixing process in step (4) is controlled by adjusting the dropping speed of the CuZnAlZr salt mixed solution and / or the precipitant mixed solution.

4. The preparation method according to any one of claims 2 to 3, wherein the water-soluble copper salt is selected from at least one of Cu(NO3)2 or its hydrate, copper sulfate or its hydrate, and copper chloride or its hydrate; and / or The water-soluble zinc salt is selected from at least one of Zn(NO3)2 or its hydrate, zinc sulfate or its hydrate, zinc chloride or its hydrate; and / or The water-soluble aluminum salt is selected from at least one of Al(NO3)3 or its hydrate, aluminum sulfate or its hydrate, aluminum chloride or its hydrate; and / or The water-soluble zirconium salt is selected from at least one of Zr(NO3)4 or its hydrate, zirconium oxychloride or its hydrate, zirconium chloride or its hydrate; and / or The precipitant comprises at least one of NaOH, Na2CO3, aqueous ammonia, urea, and potassium hydroxide; and / or Preferably, the water-soluble copper salt is selected from Cu(NO3)2·3H2O; and / or Preferably, the water-soluble zinc salt is selected from Zn(NO3)2·6H2O; and / or Preferably, the water-soluble aluminum salt is selected from Al(NO3)3·9H2O; and / or Preferably, the water-soluble zirconium salt is selected from Zr(NO3)4·5H2O; and / or Preferably, the precipitating agent comprises NaOH and Na2CO3.

5. The preparation method according to any one of claims 2 to 4, wherein the CuZnAlZr salt mixture in step (4) 2+ 、Zn 2+ 、Al 3+ and Zr 4+ The molar ratio of the feed is 2:1:x:z, x is 0.1-1, and the sum of z and x is 1. Preferably, the CuZnAlZr salt mixture contains Cu 2+ :Zn 2+ :Al 3+ :Zr 4+ The molar ratio of the feed is 2:1:x:z, x is 0.6-0.8, and the sum of z and x is 1; preferably, the Cu in the CuZnAlZr salt mixture in step (4) is 2+ 、Zn 2+ 、Al 3+ and Zr 4+ The molar ratio of the feed is 2:1:0.6:0.4, 2:1:0.7:0.3 or 2:1:0.8:0.2; and / or The precipitant includes NaOH and Na2CO3, and the molar amount of the NaOH in the precipitant solution in step (4) is equal to the molar amount of Cu in the CuZnAlZr salt mixture. 2+ 、Zn 2+ 、Al 3+ and Zr 4+ The total molar ratio of the feed is 1:1-3:1, preferably 1.5:1; the feed molar ratio of the Na2CO3 in the precipitant solution and the Al in the CuZnAlZr salt mixture is 1:1-3:1, preferably 1.5:1; 3+ The molar ratio of the feed is 1:1-3:1 or 2:

1.

6. The preparation method according to any one of claims 2 to 4, wherein the CuZnAlZr salt mixture contains Cu 2+ :Zn 2+ :Al 3+ :Zr 4+ The molar concentration ratio of Cu in the CuZnAlZr salt mixture is 2:1:x:z, x is 0.1-1, and the sum of z and x is 1. 2+ :Zn 2+ :Al 3+ :Zr 4+ The molar concentration ratio of Cu in the CuZnAlZr salt mixture is 2:1:x:z, x is 0.6-0.8, and the sum of z and x is 1; 2+ :Zn 2+ :Al 3+ :Zr 4+ The molar concentration ratio is 2:1:0.6:0.4, 2:1:0.7:0.3 or 2:1:0.8:0.2; and / or The precipitant includes NaOH and Na2CO3, and the molar concentration of the NaOH in the precipitant solution is equal to the molar concentration of Cu in the CuZnAlZr salt mixture. 2+ 、Zn 2+ 、Al 3+ and Zr 4+ The molar concentration of Na2CO3 in the precipitant solution is 1-3 times or 1.5 times of the total molar concentration. The molar concentration of Al2CO3 in the CuZnAlZr salt mixture is 3+ 1-3 times or 2 times the molar concentration; and / or In the step (4), the feed volume of the CuZnAlZr salt mixed solution and the precipitant mixed solution is 1:1-3:1 or 1:

1.

7. The preparation method according to any one of claims 2 to 6, wherein the ratio of the mass of the carbon nanotubes in the carbon nanotube mixture in step (4) to the total mass of the water-soluble copper salt, water-soluble zinc salt, water-soluble aluminum salt and water-soluble zirconium salt in the CuZnAlZr salt mixture is 1:100-10:100, preferably 4:100-6:100, more preferably 5:100; and / or The CuZnAlZr salt mixture contains Cu 2+ :Zn 2+ :Al 3+ :Zr 4+ The total molar concentration is 1 mol / L-3 mol / L or is 1 mol / L; and / or The precipitant includes NaOH and Na2CO3, the molar concentration of NaOH in the precipitant mixture is 1.5mol / L-4.5mol / L or 1.5mol / L; the molar concentration of Na2CO3 in the precipitant mixture is 3+ 1-3 times or 2 times the molar concentration.

8. The preparation method according to any one of claims 2 to 7, wherein the aging is stirring the mixed solution 1 at 50°C to 80°C; and / or The aging time is 8 hours to 16 hours, preferably 15 hours; and / or The neutral in step (5) is a pH of 6-8; and / or The drying in step (5) is carried out at 60°C-110°C, preferably 80°C; and / or The drying time in step (5) is 10 hours to 16 hours; and / or The calcination in step (5) is carried out under nitrogen atmosphere or inert gas atmosphere; and / or The calcination temperature in step (5) is 400°C-600°C, or 500°C; and / or The calcination time in step (5) is 3 hours to 6 hours, or 4 hours; and / or The granulation in step (5) is to prepare the solid obtained by calcination into particles with a particle size ranging from 0.450 mm to 0.900 mm; and / or The granulation includes a compression granulation method.

9. A composite catalyst, characterized in that The compound is prepared by the preparation method according to any one of claims 2 to 8.

10. Use of the composite catalyst according to claim 1, the composite catalyst prepared by the preparation method according to any one of claims 2 to 8, or the composite catalyst according to claim 9 in catalytic carbon dioxide hydrogenation to produce methanol.

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