Catalyst and forming method and application thereof

Abstract

The invention relates to a catalyst as well as a forming method and application thereof. The forming method comprises the following steps: mixing an aluminum source-containing aqueous solution with a first alkaline solution, and carrying out first heating reaction and first aging to obtain a first suspension; mixing a part of the first turbid liquid, a mixed aqueous solution containing a copper source, a zinc source and an M source and a second alkaline solution, carrying out a second heating reaction, and carrying out second aging to obtain a second turbid liquid; filtering and washing the second suspension, and performing first drying and first roasting on a filter cake to obtain oxide powder; mixing the other part of the first turbid liquid, an aqueous solution containing one or more of a copper source, a zinc source, an aluminum source and an M source and a third alkaline solution, and carrying out third heating reaction and third aging to obtain a third turbid liquid; filtering and washing the third suspension, and performing secondary drying on a filter cake to obtain a precursor; and mixing the oxide powder, the precursor and graphite, granulating, tabletting and molding, and then carrying out secondary roasting. The strength of the catalyst is improved through secondary roasting, and the atom utilization rate is increased.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and more specifically, to a catalyst, its forming method, and its application. Background Technology

[0002] CN114029094A discloses a method for forming an iron-containing metal composite catalyst. The method involves mixing a catalyst precursor and an additive evenly and then drying them. Lubricant, pore expander, and peptizing agent are then added and mixed again to obtain a wet material mass. The wet material mass is then placed into an extruder for extrusion forming. Finally, the formed catalyst is dried and calcined to obtain a high-strength methanol ammonia oxidation catalyst.

[0003] CN116037129A provides a method for forming a methanol catalyst, comprising the following steps: mixing catalyst powder with a binder and a pore-forming agent, then mixing it evenly with water, drying it, and grinding it to obtain a mixture with a particle size of 0.05-0.3 mm; mixing the mixture evenly with a solid lubricant, grinding it to obtain a mixture material; pressing the mixture material into tablets and granulating it, and calcining it at a temperature of 300-600℃ to obtain a methanol catalyst.

[0004] CN106102904B discloses a method for preparing a catalyst profile containing copper, zinc, and aluminum, the method comprising the following steps: (a) combining an alkaline solution with a copper-containing solution obtained by dissolving and / or suspending copper, zinc, and aluminum compounds to obtain a precipitate; (b) separating the precipitate to obtain a solid catalyst precursor; (c) heat-treating the solid catalyst precursor obtained in step (b) at a temperature in the range of 200°C to 600°C to obtain a mixed oxide; (d) mixing the solid catalyst precursor obtained in step (b) with the mixed oxide obtained in step (c) to obtain a mixture; and (e) pressing the mixture obtained in step (d) into tablets, wherein the catalyst profile has a Cu / Zn atomic ratio of 15:85 to 85:15.

[0005] In the field of CO2 hydrogenation to methanol catalysts, the development of molding technology remains a weak link. Existing technologies using extrusion processes produce catalysts with low strength, making it difficult to meet the needs of actual industrial production. While tableting processes typically require the addition of binders, pore-forming agents, and other additives to reduce molding difficulty, they introduce more impurities, affecting catalytic performance. Furthermore, after mixing the precursors, the catalyst undergoes no secondary treatment, reducing atom utilization and increasing production costs.

[0006] Therefore, there is a need to find a catalyst forming method to improve the strength of the formed catalyst, avoid introducing more impurity elements, and improve the atom utilization rate. Summary of the Invention

[0007] The purpose of this invention is to provide a catalyst, its molding method, and its application. The catalyst prepared by this molding method has high strength and high atom utilization.

[0008] To achieve the above objectives, a first aspect of the present invention provides a method for forming a catalyst, the method comprising: An aluminum-containing aqueous solution is mixed with a first alkaline solution and subjected to a first heating reaction and a first aging process to obtain a first suspension. A portion of the first suspension, a mixed aqueous solution containing copper source, zinc source, and M source, is mixed with a second alkaline solution to undergo a second heating reaction and a second aging process to obtain a second suspension. The second suspension was filtered and washed, and the resulting filter cake was subjected to a first drying and a first calcination to obtain oxide powder. Another portion of the first suspension, an aqueous solution containing one or more of the following sources (copper, zinc, aluminum, and M source), is mixed with a third alkaline solution to undergo a third heating reaction and a third aging process to obtain a third suspension; the M source includes one or more of the following sources (alkaline earth metal, rare earth metal, titanium, zirconium, and gallium). The third suspension is filtered and washed, and the resulting filter cake is subjected to a second drying process to obtain the precursor. The oxide powder, the precursor, and graphite are mixed, granulated, and pressed into tablets. After pressing, the tablets are subjected to a second calcination.

[0009] Optionally, the concentrations of the aluminum-containing aqueous solution, the mixed aqueous solution containing copper, zinc, and M sources, and one or more aqueous solutions containing copper, zinc, aluminum, and M sources are each independently 0.5-1.5 mol / L.

[0010] Optionally, the volume ratio of the aluminum-containing aqueous solution to the first alkaline solution is 0.5-2:1.

[0011] Optionally, the volume ratio of the mixed aqueous solution containing copper source, zinc source and M source to the second alkaline solution is 0.5-2:1; the molar ratio of the copper source, the zinc source and the M source is 40-70:20-55:0.5-5.

[0012] Optionally, the volume ratio of one or more aqueous solutions containing copper, zinc, aluminum, and M sources to the third alkaline solution is 0.5-2:1; the molar ratio of the copper source, zinc source, aluminum source, and M source is 40-70:20-55:3-30:0.5-5.

[0013] Optionally, the aluminum source includes one or more of aluminum nitrate, aluminum sulfate, or aluminum chloride; the copper source includes one or more of copper nitrate, copper acetate, copper sulfate, and copper chloride; and the zinc source includes one or more of zinc nitrate, zinc acetate, and zinc chloride.

[0014] Optionally, the concentrations of the first alkaline solution, the second alkaline solution, and the third alkaline solution are each independently 1-1.5 mol / L; the base in the first alkaline solution, the second alkaline solution, and the third alkaline solution independently includes one or more of sodium carbonate, sodium bicarbonate, and sodium hydroxide.

[0015] Optionally, the pH value of the system is independently controlled to be 7-8 during the first heating reaction, the second heating reaction and the third heating reaction; the reaction temperature of the first heating reaction, the second heating reaction and the third heating reaction is independently 60-80℃, and the reaction time is independently 30-200min.

[0016] Optionally, the temperature for the first aging, the second aging, and the third aging is each independently 70-90°C, and the time is each independently 50-180 min.

[0017] Optionally, the mass ratio of the oxide powder, the precursor, and the graphite is 90-100:1-10:0.5-8, preferably 93-98:3-8:1-5.

[0018] Optionally, the temperature of the first drying and the second drying are each independently 100-120°C, and the time is each independently 10-15h.

[0019] Optionally, the temperature of the first and second calcinations is independently 300-400℃, and the time is independently 2-6h.

[0020] A second aspect of the present invention provides a catalyst obtained by the molding method provided in the first aspect of the present invention; the catalyst comprises, based on its weight, the following components: CuO 40-65%, ZnO 15-30%, Al2O3 2-25%, M x O y 1-4%, graphite 0.5-8%.

[0021] Optionally, the catalyst morphology is one of the following: planar cylinder, arc-shaped cylinder, ring-shaped, spherical, clover-shaped, and honeycomb-shaped; the average pore size of the catalyst is 5-20 nm; and the specific surface area is 50-150 m². 2 / g.

[0022] Optionally, the lateral compressive strength of the catalyst is 150-450 N / cm.

[0023] The third aspect of the present invention provides the use of the catalyst provided in the second aspect of the present invention in the hydrogenation of carbon dioxide to methanol.

[0024] Through the above technical solution, this invention employs a co-precipitation method to prepare a precursor containing a single metal or a mixture of multiple metals. The precursor is mixed with the oxide powder obtained after a first calcination, pressed into tablets, and then subjected to a second calcination to obtain a shaped catalyst. This invention effectively improves the catalyst strength and reduces the difficulty of catalyst production through secondary calcination, while avoiding metal waste caused by precursor retention and improving atom utilization. Furthermore, the molding process eliminates the need for binders, pore-forming agents, etc., thus avoiding the introduction of other impurity elements. The catalyst obtained by the molding method of this invention is particularly suitable for the reaction of carbon dioxide hydrogenation to methanol.

[0025] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0026] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a pore size distribution diagram of the catalyst in Example 1 of the present invention; Figure 2 This is a SEM image of the catalyst in Example 1 of the present invention; Figure 3 This is the XRD pattern of the precursor of Embodiment 1 of the present invention; Figure 4 These are the XRD patterns of the catalysts in Example 1 and Comparative Example 1 of the present invention. Detailed Implementation

[0027] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0028] The first aspect of this invention provides a method for forming a catalyst, the method comprising: An aluminum-containing aqueous solution is mixed with a first alkaline solution and subjected to a first heating reaction and a first aging process to obtain a first suspension. A portion of the first suspension, a mixed aqueous solution containing copper source, zinc source, and M source, is mixed with a second alkaline solution to undergo a second heating reaction and a second aging process to obtain a second suspension. The second suspension was filtered and washed, and the resulting filter cake was subjected to a first drying and a first calcination to obtain oxide powder. Another portion of the first suspension, an aqueous solution containing one or more of the following sources (copper, zinc, aluminum, and M source), is mixed with a third alkaline solution to undergo a third heating reaction and a third aging process to obtain a third suspension; the M source includes one or more of the following sources (alkaline earth metal, rare earth metal, titanium, zirconium, and gallium). The third suspension is filtered and washed, and the resulting filter cake is subjected to a second drying process to obtain the precursor. The oxide powder, the precursor, and graphite are mixed, granulated, and pressed into tablets. After pressing, the tablets are subjected to a second calcination.

[0029] This invention employs a co-precipitation method to prepare a precursor containing a single metal or a mixture of multiple metals. The precursor is mixed with an oxide powder obtained after a first calcination, and after pressing into tablets, a second calcination is performed to obtain a shaped catalyst. This invention effectively improves the catalyst strength and reduces the difficulty of catalyst production through secondary calcination, while avoiding metal waste caused by precursor retention and improving atom utilization. Furthermore, the molding process eliminates the need for binders, pore-forming agents, etc., thus avoiding the introduction of other impurity elements.

[0030] According to the present invention, optionally, the concentrations of the aluminum-containing aqueous solution, the mixed aqueous solution containing copper, zinc, and M sources, and one or more aqueous solutions containing copper, zinc, aluminum, and M sources are each independently 0.5-1.5 mol / L. The concentration of the metal salt solution directly affects the size, distribution, purity, and uniformity of the precipitate. The concentration of the aluminum-containing aqueous solution affects the nucleation rate of the precipitate, thereby affecting the particle size and dispersibility of the formed alumina support; a higher concentration results in a faster nucleation rate, making it easier to form smaller particles, but may lead to uneven particle distribution and agglomeration. The concentrations of the copper, zinc, and M source aqueous solutions affect the dispersibility and interaction of the metals on the support after precipitation; a lower concentration results in greater dispersibility, preventing the metals from binding to form doped carbonate precursors, thus weakening the interaction between metals after calcination; a higher concentration leads to metal agglomeration, forming large particles, which weakens the catalyst performance.

[0031] According to the present invention, optionally, the volume ratio of the aluminum-containing aqueous source solution to the first alkaline solution is 0.5-2:1. Through the above embodiments, an aluminum hydroxide framework can be generated, which facilitates the loading of copper, zinc, and M onto the aluminum hydroxide framework.

[0032] According to the present invention, optionally, the volume ratio of the mixed aqueous solution containing copper source, zinc source, and M source to the second alkaline solution is 0.5-2:1; the molar ratio of the copper source, the zinc source, and the M source is 40-70:20-55:0.5-5. Through the above embodiments, the precipitation reaction can be better mixed with a portion of the first suspension, allowing for better contact between the precipitate and aluminum hydroxide, while avoiding the formation of hydrotalcite-like substances.

[0033] According to the present invention, optionally, the volume ratio of the aqueous solution containing one or more of the copper source, zinc source, aluminum source, and M source to the third alkaline solution is 0.5-2:1; the molar ratio of the copper source, the zinc source, the aluminum source, and the M source is 40-70:20-55:3-30:0.5-5. Through the above embodiments, the solution can be better mixed with another portion of the first suspension to carry out the precipitation reaction, and a mixed precipitate containing different metals can be generated.

[0034] According to the present invention, optionally, the aluminum source includes one or more of aluminum nitrate, aluminum sulfate, or aluminum chloride; the copper source includes one or more of copper nitrate, copper acetate, copper sulfate, and copper chloride; and the zinc source includes one or more of zinc nitrate, zinc acetate, and zinc chloride.

[0035] According to the present invention, optionally, the M source is mainly an auxiliary agent that can provide basic sites, promote the formation of polybasic carbonates, and improve the dispersion of copper.

[0036] According to the present invention, optionally, the concentrations of the first alkaline solution, the second alkaline solution, and the third alkaline solution are each independently 1-1.5 mol / L; through the above embodiments, the alkaline solution can undergo hydrolysis reaction with copper source, zinc source, aluminum source, and M source to generate sparingly soluble metal salts.

[0037] According to the present invention, optionally, the base in the first alkaline solution, the second alkaline solution and the third alkaline solution each independently includes one or more of sodium carbonate, sodium bicarbonate and sodium hydroxide.

[0038] According to the present invention, optionally, the pH value of the system is independently controlled to be 7-8 during the first heating reaction, the second heating reaction and the third heating reaction. The pH value affects the supersaturation of the solution, thereby affecting the type of precursor. By controlling the pH value of the system, the formation of zinc malachite can be promoted, and the occurrence of precursors such as hydrotalcite, copper nitrate and copper oxide can be avoided, thereby ensuring close contact between copper and zinc metals.

[0039] According to the present invention, optionally, the reaction temperature of the first heating reaction, the second heating reaction and the third heating reaction are each independently 60-80°C, and the reaction time is each independently 30-200 min.

[0040] According to the present invention, optionally, the temperature of the first aging, the second aging and the third aging are each independently 70-90°C and the time is each independently 50-180 min.

[0041] According to the present invention, optionally, the mass ratio of the oxide powder, the precursor and the graphite is 90-100:1-10:0.5-8, preferably 93-98:3-8:1-5.

[0042] According to the present invention, optionally, the temperature of the first drying and the second drying are each independently 100-120°C, and the time is each independently 10-15h.

[0043] According to the present invention, optionally, the temperature of the first calcination and the second calcination are each independently 300-400°C, and the time is each independently 2-6 hours.

[0044] A second aspect of the present invention provides a catalyst obtained by the molding method provided in the first aspect of the present invention; the catalyst comprises, based on its weight, the following components: CuO 40-65%, ZnO 15-30%, Al2O3 2-25%, M x O y 1-4%, graphite 0.5-8%.

[0045] According to the present invention, optionally, the catalyst morphology is one of planar cylinder, arc-shaped cylinder, annular, spherical, clover-shaped, and honeycomb-shaped, and the average pore size of the catalyst is 5-20 nm; the specific surface area is 50-150 m². 2 / g.

[0046] According to the present invention, optionally, the lateral pressure strength of the catalyst is 150-450 N / cm.

[0047] A third aspect of this invention provides the use of the catalyst provided in the second aspect of this invention in the hydrogenation of carbon dioxide to methanol. The catalyst is used in the hydrogenation of carbon dioxide to methanol at a reaction temperature of 210-280°C, a pressure of 2-8 MPa, and a volume hourly space velocity of 2000-4000 h⁻¹. -1 The catalyst of this invention exhibits excellent CO2 conversion, methanol selectivity, and methanol yield in the reaction of carbon dioxide hydrogenation to methanol.

[0048] The present invention will be further illustrated by the following examples, but the present invention is not limited thereto.

[0049] The instruments, methods, and conditions for XRD analysis used in the embodiments and comparative examples of this invention are as follows: X-ray diffraction analysis (XRD) is performed using a Shimadzu XRD-6000 X-ray diffractometer from Japan. The test conditions include: tube voltage 40kV, tube current 40mA, Cu target Kα radiation, 2θ scan range 10°-60°, and scan rate 5° / min.

[0050] The instruments, methods, and conditions for SEM analysis used in this embodiment of the invention are as follows: the scanning electron microscope (SEM) is a FEI Nova NanoSEM450 model with an operating voltage of 5kV.

[0051] Example 1 The catalyst forming method in this embodiment includes the following steps: S1. Add 410 mL of 1 mol / L Al(NO3)3 aqueous solution and 500 mL of 1.2 mol / L Na2CO3 solution dropwise to a stirred tank and mix them to carry out the first heating reaction. The reaction temperature is 70℃ and the time is 40 min. The pH value of the system is controlled at 8. The system is then aged at 80℃ for 50 min to obtain the first suspension. S2. Take three-quarters of the volume of the first suspension, and add dropwise 2300 mL of a 1 mol / L mixed aqueous solution of Cu(NO3)2, Zn(NO3)2, and Ga(NO3)3 and 2200 mL of a 1.2 mol / L Na2CO3 solution to carry out a second heating reaction at 70℃ for 160 min, controlling the pH of the system to 7. After the addition is complete, age the mixture at 80℃ for 2 h to obtain the second suspension; wherein the molar ratio of Cu(NO3)2, Zn(NO3)2, and Ga(NO3)3 is 63.43:34.15:2.42. S3. Filter and wash the second suspension until the conductivity of the filtrate is lower than 30 μs / cm. Then dry the filter cake at 110°C for 12 h and calcine it at 350°C for 4 h to obtain oxide powder. S4. Add 575 mL of a 1 mol / L Cu(NO3)2 and Zn(NO3)2 mixed aqueous solution and 550 mL of a 1.2 mol / L Na2CO3 solution to the remaining first suspension for a third heating reaction at 70 °C for 80 min, controlling the pH of the system to 7. After the addition is complete, age the mixture at 80 °C for 2 h to obtain the third suspension; wherein the molar ratio of Cu(NO3)2 to Zn(NO3)2 is 45.60:54.40. S5. Filter and wash the third suspension until the conductivity of the filtrate is below 30 μS / cm. Then, dry the filter cake at 110℃ for 12 hours to obtain the precursor. Figure 3 As shown, the precursors are mainly malachite, malachite-like minerals, and zinc-aluminum hydrotalcite. S6. Mix oxide powder, precursor, and graphite in a ratio of 95:5:3. Granulate the mixture under a pressure of 1.5 MPa. The compacted bulk density after granulation is 1.07 g / cm³. 3Then, the particles are pressed into tablets under a pressure of 9 kN to obtain planar cylindrical particles with a diameter of 5.4 mm and a height of 5 mm. The formed planar cylindrical particles are then calcined at 350 °C for 4 h to obtain the catalyst.

[0052] The catalyst in this embodiment comprises: CuO 60.86%, ZnO 21.64%, Al 2O 3 13.33%, Ga 2O 3 1.26%, and graphite 2.91%.

[0053] SEM images of the catalyst in this embodiment are shown below. Figure 2 As shown, the internal catalyst particles are distributed in clusters.

[0054] Example 2 The catalyst forming method in this embodiment is the same as in Example 1, except that in step S4, 575 mL of a 1 mol / L mixed aqueous solution of Cu(NO3)2, Zn(NO3)2, and Al(NO3)3 and 550 mL of a 1.2 mol / L Na2CO3 solution are added dropwise to the remaining first suspension to carry out a third heating reaction at 70°C for 120 min, with the pH of the system controlled at 7. After the addition is completed, the suspension is aged at 80°C for 2 h to obtain a third suspension. The molar ratio of Cu(NO3)2, Zn(NO3)2, and Al(NO3)3 is 63.13:30.45:6.42.

[0055] The catalyst in this embodiment comprises: CuO 63.05%, ZnO 15.51%, Al2O3 17.35%, Ga2O3 1.18%, and graphite 2.91%.

[0056] Example 3 The catalyst forming method in this embodiment is the same as in Example 1. The difference is that in step S4, 575 mL of 1 mol / L Zn(NO3)2 aqueous solution and 550 mL of 1.2 mol / L Na2CO3 solution are added dropwise to the remaining first suspension to carry out a third heating reaction. The reaction temperature is 70°C and the time is 180 min. The pH value of the system is controlled to be 7. After the addition is completed, the system is aged at 80°C for 2 h to obtain the third suspension.

[0057] The catalyst in this embodiment comprises: CuO 57.26%, ZnO 29.42%, Al2O 38.62%, Ga2O 31.79%, and graphite 2.91%.

[0058] Example 4 The catalyst forming method in this embodiment is the same as in Example 1, except that in step S6, the oxide powder, precursor, and graphite are mixed in a ratio of 90:10:3, and the mixed material is granulated under a pressure of 1.5 MPa. The compacted bulk density after granulation is 1.17 g / cm³. 3 Then, the particles are pressed into tablets under a pressure of 9 kN to obtain planar cylindrical particles with a diameter of 5.4 mm and a height of 5 mm. The formed planar cylindrical particles are then calcined at 350 °C for 4 h to obtain the catalyst.

[0059] The catalyst in this embodiment comprises: CuO 61.80%, ZnO 23.40%, Al2O3 10.77%, Ga2O3 1.12%, and graphite 2.91%.

[0060] Comparative Example 1 The molding method of this comparative catalyst includes the following steps: S1. Add 330 mL of 1 mol / L Al(NO3)3 aqueous solution and 400 mL of 1.2 mol / L Na2CO3 solution dropwise to a stirred tank and mix them to carry out the first heating reaction. The reaction temperature is 70℃ and the time is 30 min. The pH value of the system is controlled to be 8. The system is aged at 70℃ for 50 min to obtain the first suspension. S2. Add 2300 mL of a 1 mol / L mixed aqueous solution of Cu(NO3)2, Zn(NO3)2, and Ga(NO3)3 and 2200 mL of a 1.2 mol / L Na2CO3 solution to the first suspension for a second heating reaction at 70 °C for 60 min, controlling the pH of the system to 7. After the addition is complete, age the mixture at 80 °C for 2 h to obtain the second suspension; wherein the molar ratio of Cu(NO3)2, Zn(NO3)2, and Ga(NO3)3 is 64.23:33.79:1.98. S3. Filter and wash the second suspension until the conductivity of the filtrate is lower than 30 μs / cm. Then dry the filter cake at 110°C for 12 h and calcine it at 350°C for 4 h to obtain oxide powder. S4. Mix oxide powder and graphite at a ratio of 100.0:5.0. Granulate the mixture under a pressure of 1.5 MPa. The compacted bulk density after granulation is 1.1 g / cm³. 3 Then, under a pressure of 9kN, the catalyst is pressed into planar cylindrical particles with a diameter of 5.4mm and a height of 5mm to obtain the catalyst.

[0061] The catalyst in this comparative example includes: CuO 56.14%, ZnO 16.85%, Al2O3 20.71%, Ga2O3 1.54%, and graphite 4.76%.

[0062] The catalyst XRD of this comparative example is similar to that of Example 1. Figure 4 As shown, all exhibit characteristic peaks of CuO and graphite C, indicating that precursor doping does not affect the catalyst composition after secondary calcination.

[0063] Comparative Example 2 The molding method of this comparative catalyst includes the following steps: S1. Add 410 mL of 1 mol / L Al(NO3)3 aqueous solution and 500 mL of 1.2 mol / L Na2CO3 solution dropwise to a stirred tank and mix them to carry out the first heating reaction. The reaction temperature is 70℃ and the time is 70 min. The pH value of the system is controlled at 8. The system is then aged at 85℃ for 50 min to obtain the first suspension. S2. Add 2300 mL of a 1 mol / L mixed aqueous solution of Cu(NO3)2, Zn(NO3)2, and Ga(NO3)3 and 2200 mL of a 1.2 mol / L Na2CO3 solution to the first suspension for a second heating reaction at 70°C for 200 min, controlling the pH of the system to 7. After the addition is complete, age the solution at 80°C for 2 h to obtain the second suspension; wherein the molar ratio of Cu(NO3)2, Zn(NO3)2, and Ga(NO3)3 is 67.46:28.32:4.22. S3. Filter and wash the second suspension until the conductivity of the filtrate is lower than 30 μs / cm. Then dry the filter cake at 110°C for 12 h to obtain the precursor. S4. A portion of the precursor was calcined at 350°C for 4 hours to obtain oxide powder. S5. Mix the oxide powder, another portion of the precursor, and graphite in a ratio of 95:5:3. Granulate the mixture under a pressure of 1.5 MPa. The compacted bulk density after granulation is 1.11 g / cm³. 3 Then, under a pressure of 9kN, the catalyst is pressed into planar cylindrical particles with a diameter of 5.4mm and a height of 5mm to obtain the catalyst.

[0064] The catalyst in this comparative example includes: CuO 64.22%, ZnO 15.26%, Al2O3 15.08%, Ga2O3 2.43%, and graphite 2.91%.

[0065] Comparative Example 3 The catalyst forming method of this comparative example is the same as that of Example 1, except that in step S2, three-quarters of the volume of the first suspension is taken, and 2300 mL of a 1 mol / L Cu(NO3)2 and Zn(NO3)2 mixed aqueous solution and 2200 mL of a 1.2 mol / L Na2CO3 solution are added dropwise to carry out a second heating reaction at 70°C for 150 min. The pH of the system is controlled at 7. After the addition is completed, the system is aged at 80°C for 2 h to obtain the second suspension. The molar ratio of Cu(NO3)2 to Zn(NO3)2 is 68.00:32.00.

[0066] The catalyst in this comparative example includes: CuO 62.96%, ZnO 26.49%, Al2O 37.64%, and graphite 2.91%.

[0067] Test Example 1 The catalysts of Examples 1-4 and Comparative Examples 1-3 were subjected to side pressure strength, specific surface area and pore size tests, and the results are shown in Table 1.

[0068] Side pressure strength: According to HG / T 4107-2016 "Methanol Synthesis Catalysts", the side pressure strength of the catalyst was tested using a DL4A strength tester. The arithmetic mean of 40 sets of data was taken, and the unit is N / cm.

[0069] Specific surface area and pore size were determined using an ASAP2460 physical BET adsorption analyzer.

[0070] Test Example 2 The performance of the catalysts from Examples 1-4 and Comparative Examples 1-3 for CO2 hydrogenation to methanol was tested. In a fixed-bed microreactor, the catalysts were first subjected to atmospheric pressure, 240°C, and a space velocity of 10000 h⁻¹. -1 In-situ reduction in a 5% H2 / N2 mixture for 4 hours, followed by introduction of a space velocity of 3000 h⁻¹. -1 A mixture of CO2:H2:N2 = 23:71:6 was pressurized to 3 MPa and its activity was tested at 240 °C. The results are shown in Table 1.

[0071] Table 1.

[0072]

[0073] As shown in Table 1, the secondary calcination improved the specific surface area and pore structure of the catalyst in terms of physical properties, and also had a high effective gain in side pressure strength. In terms of chemical properties, the catalyst had a higher CO2 conversion rate, suppressed methane selectivity, and achieved a greater methanol yield.

[0074] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0075] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0076] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for forming a catalyst, characterized in that, The molding method includes: An aqueous solution containing an aluminum source is mixed with a first alkaline solution and subjected to a first heating reaction and a first aging process to obtain a first suspension. A portion of the first suspension, a mixed aqueous solution containing copper source, zinc source, and M source, is mixed with a second alkaline solution to undergo a second heating reaction and a second aging process to obtain a second suspension. The second suspension was filtered and washed, and the resulting filter cake was subjected to a first drying and a first calcination to obtain oxide powder. Another portion of the first suspension, an aqueous solution containing one or more of the following sources (copper, zinc, aluminum, and M source), is mixed with a third alkaline solution to undergo a third heating reaction and a third aging process to obtain a third suspension; the M source includes one or more of the following sources (alkaline earth metal, rare earth metal, titanium, zirconium, and gallium). The third suspension is filtered and washed, and the resulting filter cake is dried a second time to obtain the precursor. The oxide powder, the precursor, and graphite are mixed, granulated, and pressed into tablets. After pressing, the tablets are subjected to a second calcination.

2. The molding method according to claim 1, wherein, The concentrations of the aluminum-containing aqueous solution, the mixed aqueous solution containing copper, zinc, and M sources, and one or more aqueous solutions containing copper, zinc, aluminum, and M sources are each independently 0.5-1.5 mol / L; The volume ratio of the aluminum-containing aqueous solution to the first alkaline solution is 0.5-2:1; The volume ratio of the mixed aqueous solution containing copper source, zinc source and M source to the second alkaline solution is 0.5-2:1; the molar ratio of the copper source, the zinc source and the M source is 40-70:20-55:0.5-5; The volume ratio of one or more aqueous solutions containing copper, zinc, aluminum, and M sources to the third alkaline solution is 0.5-2:1; the molar ratio of the copper source, zinc source, aluminum source, and M source is 40-70:20-55:3-30:0.5-5.

3. The molding method according to claim 1, wherein, The aluminum source includes one or more of aluminum nitrate, aluminum sulfate, or aluminum chloride; the copper source includes one or more of copper nitrate, copper acetate, copper sulfate, or copper chloride; and the zinc source includes one or more of zinc nitrate, zinc acetate, or zinc chloride.

4. The molding method according to claim 1, wherein, The concentrations of the first alkaline solution, the second alkaline solution, and the third alkaline solution are each independently 1-1.5 mol / L; The base in the first alkaline solution, the second alkaline solution, and the third alkaline solution each independently includes one or more of sodium carbonate, sodium bicarbonate, and sodium hydroxide.

5. The molding method according to claim 1, wherein, The pH value of the system is independently controlled to be 7-8 during the first heating reaction, the second heating reaction, and the third heating reaction. The reaction temperatures of the first heating reaction, the second heating reaction, and the third heating reaction are each independently 60-80℃, and the reaction times are each independently 30-200min; The temperatures for the first, second, and third aging processes are each independently 70-90°C, and the time for each is independently 50-180 minutes.

6. The molding method according to claim 1, wherein, The mass ratio of the oxide powder, the precursor, and the graphite is 90-100:1-10:0.5-8, preferably 93-98:3-8:1-5.

7. The molding method according to claim 1, wherein, The temperature for the first drying and the second drying are each independently 100-120℃, and the time is each independently 10-15h; The first and second roasting temperatures are each independently 300-400℃, and the times are each independently 2-6h.

8. A catalyst, characterized in that, The catalyst is obtained by the molding method according to any one of claims 1-7; based on the weight of the catalyst, the catalyst comprises the following components: CuO 40-65%, ZnO 15-30%, Al2O3 2-25%, M x O y 1-4%, graphite 0.5-8%.

9. The catalyst according to claim 8, wherein, The catalyst has a morphology selected from the following: planar cylinder, arc-shaped cylinder, ring-shaped, spherical, clover-shaped, and honeycomb-shaped. The average pore size of the catalyst is 5-20 nm; the specific surface area is 50-150 m². 2 / g; The catalyst has a lateral compressive strength of 150-450 N / cm.

10. Use of the catalyst according to claim 8 or 9 in the hydrogenation of carbon dioxide to methanol.

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