Hydrotalcite-derived indium-based catalyst as well as preparation method and application of supported palladium of hydrotalcite-derived indium-based catalyst

Abstract

The invention provides a hydrotalcite-derived indium-based catalyst and a preparation method and application of palladium loaded on the hydrotalcite-derived indium-based catalyst, and the preparation method comprises the following steps: mixing indium salt of In < 3 + >, zinc salt of Zn < 2 + >, aluminum salt of Al < 3 + > and water to obtain a mixed salt solution; mixing an alkaline compound containing hydroxyl and / or carbonate to obtain an alkaline solution; the preparation method comprises the following steps: dropwise adding an alkali solution and a mixed salt solution into water, controlling the pH value of a turbid liquid to be 7-14, after dropwise adding the mixed salt solution, crystallizing, carrying out solid-liquid separation, washing to be neutral, drying to obtain a layered double-metal hydroxide, and carrying out structural topology transformation and reduction to obtain the hydrotalcite-derived indium-based catalyst. According to the method, metal elements of hydrotalcite are adjustable, metal is highly dispersed after structural topology transformation, and an intercalation structure is still kept, so that microstructure regulation and control of indium, zinc and aluminum are achieved. The catalyst can continuously load palladium, has good dispersibility, can regulate and control the geometric structure and electronic characteristics of a metal-carrier interface, and has excellent catalytic reaction performance when being applied to CO / CO2 hydrogenation reaction.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, and particularly relates to a hydrotalcite-derived indium-based catalyst and its preparation method and application, specifically to a method for preparing a hydrotalcite-derived indium-based catalyst and a method for preparing a hydrotalcite-derived indium-based catalyst supported on palladium and its application. Background Technology

[0002] With population growth and increased human activity, the consumption of fossil fuels such as coal, oil, and natural gas has led to a continuous rise in atmospheric carbon dioxide concentration, causing numerous environmental problems such as global warming, sea-level rise, and environmental pollution. Therefore, CO2 emission reduction and conversion utilization have both environmental protection and resource utilization significance. Among many catalytic conversion pathways, hydrogen produced using renewable energy can react with CO2 to form alcohols, effectively reducing carbon emissions and offering economic benefits. Methanol, as one of the products of CO2 hydrogenation, is a good fuel energy carrier and gasoline additive due to its high volumetric energy density and octane number. Furthermore, methanol can be used as an upstream product to synthesize other commodities and as an intermediate for special products such as light olefins, dimethyl ether, and gasoline, and is widely used in chemical, pesticide, and pharmaceutical fields.

[0003] However, CO2 is in a fully oxidized state with a C=O bond energy as high as 803 kJ / mol, resulting in high thermodynamic stability and thus requiring high energy to activate. From a kinetic perspective, low temperatures reduce the chemical reaction rate, therefore CO2 activation requires higher temperatures; however, high temperatures easily lead to the generation of byproducts such as CO, mainly resulting in side reactions such as reverse water gasification and CO hydrogenation to methanol. Furthermore, CO2 hydrogenation to methanol involves multiple different reactions, with complex pathways and numerous steps, leading to a lack of clarity in the reaction mechanism. In addition, the scale of its heterogeneous catalytic conversion to methanol is small, the reaction selectivity is low, and its economic efficiency needs improvement. Therefore, designing efficient, low-energy-consumption, and highly selective catalysts for CO2 hydrogenation to methanol is currently the main development approach.

[0004] Among numerous catalysts, Pd-based catalysts not only possess excellent hydrogen dissociation characteristics, but the interaction between Pd and the metal / support can also modulate the electronic properties and geometry of Pd-based catalysts, thereby promoting CO2 adsorption and activation. Chinese patent CN105727942A discloses a palladium / carbon nanotube catalyst. However, the catalyst is limited to carbon nanotube-based supports, which are inherently costly and have complex preparation processes. Furthermore, the excellent hydrogenation capabilities of noble metal catalysts often lead to the formation of byproducts such as methane or CO. Indium oxide catalysts rich in oxygen vacancies exhibit excellent CO2 adsorption and activation capabilities, and show good CO2 hydrogenation activity when used in combination with other oxides (such as zirconium oxide). However, their activity is weaker than Cu-based catalysts, and the catalyst itself has poor stability, which limits the widespread use of indium oxide-based catalysts. Chinese patent CN116037107A discloses a Pd-supported magnesium-aluminum-doped indium oxide catalyst for CO2 hydrogenation to methanol production. It has a high indium oxide content and is relatively expensive. Therefore, designing the microstructure of Pd or In-based catalysts and preparing supported, highly efficient catalysts remains a key challenge in the field of catalytic materials. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a hydrotalcite-derived indium-based catalyst and its preparation method and application with supported palladium. This catalyst utilizes the tunable metal elements of hydrotalcite, and after a structural topological transformation, the metal is highly dispersed while still maintaining its intercalation structure, thereby achieving microstructural control of indium, zinc, and aluminum in the indium-based catalyst. Furthermore, the supported Pd exhibits good dispersion, and the interaction between the Pd metal and the InZnAl support effectively regulates the electronic and geometric structure of the catalyst, resulting in high catalytic performance when used in CO or CO2 hydrogenation reactions.

[0006] This invention provides a method for preparing a hydrotalcite-derived indium-based catalyst, comprising the following steps:

[0007] In 3+ Indium salts, Zn 2+ Zinc salts, Al 3+ Aluminum salts are mixed with water to obtain a mixed salt solution; basic compounds containing hydroxide ions and / or carbonates are mixed to obtain an alkaline solution.

[0008] An alkaline solution and a mixed salt solution were added dropwise to water, and the pH of the suspension was controlled at 7-14. After the mixed salt solution was added, the suspension was liquidized, and the solid and liquid were separated. The obtained solid was washed until neutral and dried to obtain a layered bimetallic hydroxide. Then, a structural topological transformation and reduction were performed to obtain a hydrotalcite-derived indium-based catalyst.

[0009] This invention provides a method for preparing palladium supported on a hydrotalcite-derived indium-based catalyst, comprising the following steps:

[0010] The unreduced indium-based hydrotalcite catalyst in the above technical solution is loaded with palladium salt by impregnation or precipitation, and then calcined and reduced to obtain palladium-loaded hydrotalcite-derived indium-based catalyst.

[0011] Preferably, the palladium salt supported by the hydrotalcite indium-based catalyst precipitation method comprises:

[0012] Unreduced hydrotalcite-derived indium-based catalyst was dispersed in deionized water and then Pd-containing catalyst was added under stirring conditions. 2+ The palladium salt was then adjusted to pH 8-11 and stirred in a water bath at 40-100℃ for 1-12 hours. The resulting precipitate was washed, dried, and then calcined and reduced to obtain palladium supported on a hydrotalcite-derived indium-based catalyst.

[0013] Preferably, the palladium salt supported by the hydrotalcite indium-based catalyst impregnation method comprises:

[0014] Pd-containing 2+ The palladium salt solution was added dropwise to the unreduced hydrotalcite-derived indium catalyst, stirred at 10-35°C for 1-12 h, dried under vacuum, and then subjected to structural topological transformation and reduction to obtain the hydrotalcite-derived indium-supported palladium catalyst.

[0015] This invention provides a method for preparing palladium supported on a hydrotalcite-derived indium-based catalyst, comprising the following steps:

[0016] Pd-containing 2+ palladium salts, In 3+ Indium salt, Zn 2+ Zinc salts and Al 3+ Aluminum salts are mixed with water to obtain a mixed salt solution; basic compounds containing hydroxide ions and / or carbonates are mixed to prepare an alkaline solution.

[0017] An alkaline solution and a mixed salt solution were added dropwise to water, and the pH of the suspension was controlled at 7-14. After the mixed salt solution was added, the suspension was liquidized, and the solid and liquid were separated. The obtained solid was washed until neutral and dried to obtain a layered bimetallic hydroxide. Then, a structural topological transformation and reduction were performed to obtain a palladium-supported indium catalyst derived from hydrotalcite.

[0018] Preferably, the crystallization temperature is 40~100℃, and the crystallization time is 1~12h;

[0019] The atmosphere for the structural topology transformation treatment is selected from one or more of vacuum, nitrogen, argon, helium, air, and hydrogen. The temperature for the structural topology transformation treatment is 400~800℃, and the time is 2~6h.

[0020] The reduction is carried out using hydrogen at a temperature of 100~500℃ for 2~6 hours.

[0021] Preferably, Zn 2+ With Al 3+ The molar ratio is (1~4):1;

[0022] Zn 2+ With Al 3+ The sum of their molar concentrations is 0.1~1 mol / L;

[0023] In 3+ The molar concentration is 0.0001~1 mol / L;

[0024] In 3+ With Al 3+ The molar ratio is (1~1000):1000.

[0025] Preferably, the palladium loading in the hydrotalcite-derived indium-based catalyst is 0.01~3 wt.%.

[0026] Preferably, the hydroxide-containing basic compound is selected from sodium hydroxide or potassium hydroxide; the carbonate is selected from sodium carbonate or potassium carbonate.

[0027] The molar ratio of the hydroxide-containing basic compound to the carbonate is (1~5):1;

[0028] The sum of the molar concentrations of the hydroxide-containing basic compound and the carbonate is 0.5~5 mol / L;

[0029] The volume ratio of the mixed salt solution to the alkaline solution is (0.1~5):1;

[0030] The molar concentration of carbonate in the alkaline solution is 0.1~1 mol / L;

[0031] The molar concentration of the basic compound containing hydroxide ions in the alkaline solution is 0.1~4 mol / L.

[0032] This invention provides the application of a hydrotalcite-derived indium-based catalyst prepared by the preparation method described above, or a hydrotalcite-derived indium-based supported palladium catalyst prepared by the same method, in the hydrogenation of CO or CO2 to methanol.

[0033] The reaction conditions for methanol production include: a reaction temperature of 180–300 °C; a reaction pressure of 0.1–10 MPa; a volume ratio of H2:CO or CO2 in the reaction mixture of 1–6; and a mass hourly space velocity (WHSV) of 9000–40000 mL·g. cat -1 ·h -1The volumetric flow rate of CO or the mixture of CO2 and H2 is 10~200 mL / min; the balance gas of the mixture is selected from one or more of nitrogen, argon and helium.

[0034] This invention provides a method for preparing a hydrotalcite-derived indium-based catalyst, comprising the following steps: [The method involves] mixing In... 3+ Indium salts, Zn 2+ Zinc salts, Al 3+ Aluminum salts and water are mixed to obtain a mixed salt solution; an alkaline compound containing hydroxide ions and / or a carbonate are mixed to obtain an alkaline solution; the alkaline solution and the mixed salt solution are added dropwise to water, controlling the pH of the suspension to 7-14. After the mixed salt solution is completely added, the suspension is liquidized, and solid-liquid separation is performed. The obtained solid is washed to neutral, dried, and a layered bimetallic hydroxide is obtained. This is then subjected to structural topological transformation and reduction to obtain a hydrotalcite-derived indium-based catalyst. The preparation method of palladium-supported hydrotalcite-derived indium-based catalyst of this invention uses indium salts, zinc salts, and aluminum salts as raw materials, and an alkaline compound containing hydroxide ions and / or a carbonate as a precipitant. A constant pH method is used to obtain the hydrotalcite-derived indium-based catalyst; subsequently, palladium-supported hydrotalcite-derived indium-based catalyst is obtained through impregnation, precipitation, and constant pH methods. The preparation method of this invention utilizes the tunable metal elements of hydrotalcite, and the high dispersion of the metal after structural topological transformation while maintaining the intercalation structure, thereby achieving microstructural control of indium, zinc, and aluminum in the indium-based catalyst. Furthermore, the palladium prepared by this method exhibits good dispersion, and the geometry and electronic properties of the metal-support interface are tunable. When used in the carbon monoxide / carbon dioxide hydrogenation reaction, it also possesses excellent catalytic performance. Attached Figure Description

[0035] Figure 1 TEM images, (a2 - e2) HRTEM images, and (a3 - e4) fast Fourier transform images of palladium catalysts supported on hydrotalcite-derived indium-based catalysts with different In contents are shown. a~e correspond to the catalysts of Example 3 and Examples 14-17, respectively.

[0036] Figure 2 TEM images, (a2 - e2) HRTEM images, and (a3 - e4) fast Fourier transform images of palladium catalysts supported on hydrotalcite-derived indium-based catalysts with different Pd contents are shown. a~e correspond to the catalysts of Example 22 and Examples 18-21, respectively.

[0037] Figure 3 XRD patterns of InZnAl-hydrotalcite with different In contents (Examples 14-17). Detailed Implementation

[0038] This invention provides a method for preparing a hydrotalcite-derived indium-based catalyst, comprising the following steps:

[0039] In 3+ Indium salts, Zn 2+ Zinc salts, Al 3+ Aluminum salts are mixed with water to obtain a mixed salt solution; basic compounds containing hydroxide ions and / or carbonates are mixed to obtain an alkaline solution.

[0040] An alkaline solution and a mixed salt solution were added dropwise to water, and the pH of the suspension was controlled at 7-14. After the mixed salt solution was added, the suspension was liquidized, and the solid and liquid were separated. The obtained solid was washed until neutral and dried to obtain a layered bimetallic hydroxide. Then, a structural topological transformation and reduction were performed to obtain a hydrotalcite-derived indium-based catalyst.

[0041] This invention will In 3+ Indium salts, Zn 2+ Zinc salts, Al 3+ Aluminum salts are mixed with water to obtain a mixed salt solution. In this invention, the water used is one or more of deionized water, distilled water, and ultrapure water, preferably deionized water. In this invention, In... 3+ The Zn is provided by one or more of indium nitrate hydrate and indium chloride; more preferably by indium nitrate hydrate. 2+ It is provided by one or more of zinc nitrate hexahydrate, zinc acetate, and zinc chloride, preferably zinc nitrate hexahydrate. In this invention, Al 3+ It is provided by one or more of aluminum nitrate nonahydrate, aluminum chloride hexahydrate and anhydrous aluminum chloride, more preferably by aluminum nitrate nonahydrate.

[0042] The Zn described in this invention 2+ With Al 3+ The molar ratio is (1~4):1, preferably (2~4):1, and more preferably 3:1. The Zn 2+ With Al 3+ The sum of the molar concentrations is 0.1~1 mol / L, preferably 0.2~0.5 mol / L, and more preferably 0.4 mol / L.

[0043] In this invention In 3+ The molar concentration of In is 0.0001~1 mol / L, preferably 0.0001~0.07 mol / L; In this invention 3+ With Al 3+ The molar ratio is (1~1000):1000; more preferably (1~800):1000.

[0044] The hydroxide-containing basic compound described in this invention is selected from sodium hydroxide or potassium hydroxide, preferably sodium hydroxide. The carbonate described in this invention is selected from sodium carbonate or potassium carbonate, preferably sodium carbonate. The sum of the molar concentrations of the hydroxide-containing basic compound and the carbonate in this invention is 0.1~5 mol / L, specifically 0.1 mol / L, 0.5 mol / L, 1.0 mol / L, 1.5 mol / L, 2.0 mol / L, 2.5 mol / L, 3.0 mol / L, 3.5 mol / L, 4.0 mol / L, 4.5 mol / L, or 5.0 mol / L, preferably 1~3 mol / L, more preferably 1.2 mol / L. The alkaline solution in this invention is preferably a mixed alkaline solution, i.e., a mixed alkaline solution of the hydroxide-containing basic compound and the carbonate; the molar concentration of the carbonate in the mixed alkaline solution is 0.1~1 mol / L, preferably 0.5 mol / L. The molar concentration of the alkaline compound in the mixed alkaline solution of the present invention is 0.1~4 mol / L, specifically 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1.0 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L, 2.0 mol / L, 2.1 mol / L, 2.2 mol / L, 2.3 mol / L, 2.4 mol / L, 2.5 mol / L, 2.6 mol / L, 2.7 mol / L, 2.8 mol / L, etc. The concentrations are 2.9 mol / L, 3.0 mol / L, 3.1 mol / L, 3.2 mol / L, 3.3 mol / L, 3.4 mol / L, 3.5 mol / L, 3.6 mol / L, 3.7 mol / L, 3.8 mol / L, 3.9 mol / L, or 4 mol / L. In this invention, the molar ratio of the hydroxide-containing basic compound to the carbonate is (1~5):1; more preferably (1~4):1; and even more preferably 4:1.

[0045] In this invention, the volume ratio of the mixed salt solution to the mixed alkali solution is (0.1~5):1, preferably (0.1~2):1; in a specific embodiment of this invention, the volume ratio of the mixed salt solution to the mixed alkali solution is 1:1.

[0046] In this invention, a mixed alkaline solution and a mixed salt solution are added dropwise to water, and the pH of the suspension is controlled to be 7-14, preferably 8-14, and more preferably 8-10. Preferably, the mixed alkaline solution and the mixed salt solution are added dropwise to 10-50 mL of water.

[0047] In this invention, the pH value of the system is kept constant during the mixing of the mixed salt solution and the mixed alkali solution. Specifically, the pH value can be kept constant by controlling the dropping speed and stirring speed. This invention monitors the pH value of the system with a pH meter and controls it to remain constant, ensuring that the carrier precursor (indium zinc aluminum hydrotalcite layer) has a suitable layered structure, thereby preventing the metal from failing to enter the hydrotalcite layer and forming large particles with uneven dispersion.

[0048] In this invention, continuous stirring is required during the dropwise addition of the mixed salt solution. The stirring rate is 3000~10000 rpm, more preferably 6000~8000 rpm.

[0049] After the mixed salt solution is added dropwise, the suspension is transferred to a constant temperature water bath, and the crystallization temperature is controlled at 40~100℃ while continuously stirring for 1~12 hours. Specifically, the crystallization temperature is 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, or 100℃; the crystallization time is specifically 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, or 12 hours.

[0050] In this invention, solid-liquid separation is performed after crystallization, and the solid is washed with deionized water until neutral.

[0051] The present invention does not specifically limit the washing method described in the above preparation method, and can use methods well known to those skilled in the art such as centrifugation, vacuum filtration, and atmospheric pressure filtration.

[0052] After washing until neutral, the solid is dried. This invention does not impose any particular limitation on the drying method; it can be any method well-known to those skilled in the art, such as atmospheric pressure drying, vacuum drying, or freeze drying. In a specific embodiment, a constant temperature oven is used for drying. The drying temperature is 40~90℃, specifically 40℃, 50℃, 60℃, 70℃, 80℃, or 90℃; the drying time is 6~12 hours, specifically 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, or 12 hours.

[0053] After drying, a layered bimetallic hydroxide is obtained. This invention involves subjecting the layered bimetallic hydroxide to a topological transformation and reduction to obtain a hydrotalcite-derived indium-based catalyst. The atmosphere for the topological transformation treatment in this invention is selected from one or more of vacuum, nitrogen, argon, helium, and air; more preferably, the atmosphere for the topological transformation treatment is air. The temperature for the topological transformation treatment in this invention is 400~800℃, specifically 400℃, 450℃, 500℃, 550℃, 600℃, 650℃, 700℃, 750℃, or 800℃. The time for the topological transformation treatment in this invention is 2~6 hours, specifically 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, or 6 hours. In this invention, the reduction is performed using hydrogen reduction at a temperature of 100~500℃ for 2~6 hours.

[0054] This invention provides a method for preparing palladium supported on a hydrotalcite-derived indium-based catalyst, comprising the following steps:

[0055] The unreduced indium-based hydrotalcite catalyst in the above technical solution is loaded with palladium salt by impregnation or precipitation, and then calcined and reduced to obtain palladium-loaded hydrotalcite-derived indium-based catalyst.

[0056] The palladium salt supported by the precipitation method of the hydrotalcite indium-based catalyst described in this invention includes:

[0057] Unreduced hydrotalcite-derived indium-based catalyst was dispersed in deionized water and then Pd-containing catalyst was added under stirring conditions. 2+ The palladium salt solution was prepared, and the pH was adjusted to 8-11. The mixture was stirred in a water bath at 40-100℃ for 1-12 hours. The resulting precipitate was washed, dried, and then subjected to structural topological transformation and reduction to obtain palladium supported on a hydrotalcite-derived indium-based catalyst.

[0058] Specifically, this invention uses ultrasonic assistance to disperse a hydrotalcite-derived indium-based catalyst into deionized water, and magnetic stirring is used to add a Pd-containing catalyst. 2+ The palladium salt is used. Preferably, a carbonate solution is used to adjust the pH to 8-11, specifically sodium carbonate; the adjusted pH value is 8, 9, 10, or 11. The sediment is preferably washed with deionized water to remove sodium ions; the drying method is vacuum drying, with a vacuum drying temperature of 40-90℃, specifically 40℃, 50℃, 60℃, 70℃, 80℃, or 90℃; the time is 1-12 hours, specifically 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, or 12 hours.

[0059] The palladium salt supported by the hydrotalcite indium-based catalyst impregnation method described in this invention includes:

[0060] Pd-containing2+ The palladium salt solution was added dropwise to the unreduced hydrotalcite-derived indium catalyst in the above technical solution, stirred at 10~35℃ for 1~12h, dried under vacuum, and then subjected to structural topological transformation treatment and reduction to obtain the hydrotalcite-derived indium-supported palladium catalyst.

[0061] In this invention, the temperature for the structural topological transformation treatment when palladium is loaded is 400-800°C, and the time is 2-6 hours. Reduction is carried out in a hydrogen atmosphere at a temperature of 100-500°C, specifically 100°C, 150°C, 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, or 500°C; the reduction time is 2-6 hours, specifically 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 5 hours, 5 hours, 5.5 hours, or 6 hours. The hydrogen volume content in the hydrogen atmosphere used for reduction is 5-100%, specifically 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100%; preferably 10-100%.

[0062] The Pd content in the palladium supported on the hydrotalcite-derived indium-based catalyst provided by this invention is 0.01~3 wt.%; specifically, 0.01 wt.%, 0.05 wt.%, 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, 0.8 wt.%, 0.9 wt.%, 1.0 wt.%, 1.1 wt.%, 1.2 wt.%, 1.3 wt.%, 1.4 wt.%, 1.5 wt.%, 1.6 wt.%, 1.7 wt.%, 1.8 wt.%, 1.9 wt.%, 2.0 wt.%, 2.1 wt.%, 2.2 wt.%, 2.3 wt.% wt.%, 2.4wt.%, 2.5wt.%, 2.6wt.%, 2.7wt.%, 2.8wt.%, 2.9wt.%, or 3wt.%; more preferably 0.1~1.6wt.%; the In content is 0.1~20 wt.%, specifically 0.1wt.%, 0.5wt.%, 1wt.%, 2wt.%, 3wt.%, 4wt.%, 5wt.%, 6wt.%, 7wt.%, 8wt.%, 9wt.%, 10wt.%, 11wt.%, 12wt.%, 13wt.%, 14wt.%, 15wt.%, 16wt.%, 17wt.%, 18wt.%, 19wt.%, or 20wt.%; more preferably 0.1~15wt.%.

[0063] In₂O₃-based catalysts exhibit high methanol selectivity and excellent stability at high temperatures. Furthermore, the abundant oxygen vacancies on their surface not only activate CO₂ but also interact with other metals, thereby modulating CO₂ conversion and methanol selectivity. Adding Pd effectively improves hydrogen dissociation activation, thus increasing the reaction efficiency of CO₂ and H₂. Therefore, it is necessary to design highly efficient Pd surface hydrogenation active sites and Pd-InO₃-based catalysts. x Catalysts with interfacial interactions can effectively increase methanol production and give the catalysts excellent catalytic performance.

[0064] This invention provides the application of a hydrotalcite-derived indium-based catalyst prepared by the preparation method described above, or a hydrotalcite-derived indium-based supported palladium catalyst prepared by the same method, in the hydrogenation of CO or CO2 to methanol.

[0065] The reaction conditions for methanol production include: a reaction temperature of 180~300℃, specifically 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, 290℃, or 300℃, preferably 200~300℃; a reaction pressure of 0.1~10MPa, specifically 0.1MPa, 0.5MPa, 1 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, 3MPa, 3.5 MPa, 4 MPa, 4.5 MPa, 5 MPa, 5.5 MPa, 6 MPa, 6.5 MPa, 7 MPa, 7.5 MPa, 8 MPa, 8.5 MPa, 9 MPa, 9.5 MPa, or 10 MPa, preferably 3~5 MPa; and H2 in the reaction mixture. The volume ratio of CO or CO2 is 1 to 6, specifically 1, 2, 3, 4, 5, or 6, preferably 2 to 5; the mass hourly space velocity is 9000 to 40000 mL·g. cat -1 ·h -1 Specifically, it can be 9000 mL·g cat -1 ·h -1 9600 mL·g cat -1 ·h -1 10000 mL·g cat -1 ·h -1 15000 mL·g cat -1 ·h -1 20000 mL·g cat -1 ·h -1 25000 mL·g cat-1 ·h -1 30000 mL·g cat -1 ·h -1 35000 mL·g cat -1 ·h -1 Or 40000 mL·g cat -1 ·h -1 The volumetric flow rate of CO or the mixture of CO2 and H2 is 10~200 mL / min, specifically 10 mL / min, 20 mL / min, 30 mL / min, 40 mL / min, 50 mL / min, 60 mL / min, 70 mL / min, 80 mL / min, 90 mL / min, 100 mL / min, 110 mL / min, 120 mL / min, 130 mL / min, 140 mL / min, 150 mL / min, 160 mL / min, 170 mL / min, 180 mL / min, 190 mL / min or 200 mL / min; the balance gas of the mixture is selected from one or more of nitrogen, argon and helium.

[0066] The method for preparing palladium supported on a hydrotalcite-derived indium-based catalyst of this invention uses indium salts, zinc salts, and aluminum salts as raw materials, and basic compounds and / or carbonates containing hydroxide ions as precipitants. A constant pH method is used to obtain the hydrotalcite-derived indium-based catalyst, followed by impregnation, precipitation, and constant pH methods to obtain palladium supported on the hydrotalcite-derived indium-based catalyst. Furthermore, the effects of different structural topological transformation processes, pretreatment temperature, and the contents of Pd and In on reaction performance were explored. The preparation method of this invention utilizes the tunable metal element in hydrotalcite, and the highly dispersed metal after structural topological transformation while maintaining the intercalation structure, thereby achieving microstructural control of indium in the indium-based catalyst. In addition, the palladium prepared by this method exhibits good dispersion and tunable electronic properties of the metal-support interface structure, demonstrating excellent catalytic performance when used in the carbon monoxide / carbon dioxide hydrogenation reaction.

[0067] To further illustrate the present invention, the following detailed description, in conjunction with embodiments, provides a method for preparing and applying a hydrotalcite-derived indium-based catalyst and its supported palladium. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0068] Example 1

[0069] (I) Preparation of Pd-S1 catalyst

[0070] 1) Indium nitrate hydrate, zinc nitrate hexahydrate, and aluminum nitrate nonahydrate were added at a molar ratio of divalent to trivalent ions of 2:1, using deionized water as the solvent. The mixture was stirred thoroughly until completely dissolved, yielding a 100 mL, 0.45 mol / L mixed salt solution. Sodium hydroxide and sodium carbonate were prepared into a 100 mL, 1.2 mol / L mixed alkali solution, and stirred thoroughly until completely dissolved. In another beaker, 50 mL of distilled water was added, and the alkali and salt solutions were slowly added dropwise while continuously stirring. The pH of the suspension was controlled at 8 ± 0.5 using a pH meter. After all the salt solutions had been added, the suspension was transferred to a constant-temperature water bath and crystallized at 70°C with continuous stirring for 5 hours. After crystallization, solid-liquid separation was performed, and the solid was washed with deionized water until neutral. The solid was then dried in a 60°C oven for 12 hours. The obtained catalyst precursor was a layered bimetallic hydroxide. The resulting solid powder was further subjected to a topological transformation treatment at 500℃ for 4 h to obtain a layered hydrotalcite-derived indium catalyst, i.e., an unreduced hydrotalcite-derived indium catalyst. The layered hydrotalcite-derived indium catalyst was dispersed in 100 mL of deionized water using ultrasonic assistance. 50 mL of palladium nitrate solution (containing 0.005 g Pd) was added under magnetic stirring. The pH of the solution was then adjusted to 10 with 0.5 M sodium carbonate, followed by stirring in a 60℃ water bath for 3 h. The resulting precipitate was washed with deionized water to remove sodium ions and then vacuum dried at 60℃ for 12 h. The resulting solid powder was further subjected to a topological transformation treatment at 400℃ for 4 h, and finally dried at 500℃ with a total flow rate of 50 mL / min. -1 The catalyst was reduced in a 1:4 H2:N2 mixture for 2 h to obtain a layered double hydroxide-derived indium-based catalyst supported on palladium Pd-S1.

[0071] In the Pd-S1 catalyst provided in this embodiment, the mass content of Pd is 0.5 wt% and the mass content of In is 12 wt%, based on the mass of the catalyst being 100%.

[0072] (II) Pd-S1 catalyst for catalytic hydrogenation of carbon dioxide

[0073] Weigh 0.3 g of Pd-S1 catalyst and mix it evenly with 0.3 g of 40-60 mesh quartz sand. Place the mixture in a quartz reaction tube and introduce a hydrogen-nitrogen mixture with a total volume flow rate of 50 mL / min and a hydrogen volume concentration of 20%. Pretreat at 200℃ for 2 h. After pretreatment and reduction, shut off the H2 gas and use N2 for pressure leak detection. After confirming no leaks, shut off N2. Introduce a mixed reaction gas (CO2 / H2 = 1 / 3, V / V) and pressurize to 5 MPa. Raise the temperature to 270℃ and adjust the mixed gas flow rate to 48 mL / min. -1The mass hourly space velocity (MSV) of the mixed reaction gas is 9600 mL·g. cat -1 ·h -1 .

[0074] Product monitoring: During the reaction, the products at different reaction times are analyzed. The detection method is as follows: after the reaction reaches steady state, the products of the reaction system are collected every 20 minutes.

[0075] The resulting carbon dioxide reaction rate, methanol selectivity, and space-time yield are shown in Table 1.

[0076] Example 2

[0077] (I) Preparation of Pd-S2 catalyst

[0078] 1) Indium nitrate hydrate, zinc nitrate hexahydrate, and aluminum nitrate nonahydrate were added at a molar ratio of divalent to trivalent ions of 2:1, using deionized water as the solvent. The mixture was stirred thoroughly until completely dissolved, yielding a 100 mL, 0.45 mol / L mixed salt solution. Sodium hydroxide and sodium carbonate were prepared into a 100 mL, 1.2 mol / L mixed alkali solution, and stirred thoroughly until completely dissolved. In another beaker, 50 mL of distilled water was added, and the alkali and salt solutions were slowly added dropwise while continuously stirring. The pH of the suspension was controlled at 8 ± 0.5 using a pH meter. After all the salt solutions had been added, the suspension was transferred to a constant-temperature water bath and crystallized at 70°C with continuous stirring for 5 hours. After crystallization, solid-liquid separation was performed, and the solid was washed with deionized water until neutral. The solid was then dried in a 60°C oven for 12 hours. The obtained catalyst precursor was a layered bimetallic hydroxide. The resulting solid powder was further subjected to a topological transformation treatment at 500℃ for 4 h to obtain a hydrotalcite-derived indium catalyst with an intercalated structure, i.e., an unreduced hydrotalcite-derived indium catalyst. Palladium nitrate solution (containing 0.005 g Pd) was uniformly added dropwise to the hydrotalcite-derived indium catalyst, stirred at room temperature for 4 h, and then vacuum dried at 60℃ for 12 h. The resulting solid powder was further subjected to a topological transformation treatment at 400℃ for 4 h, and finally dried at 500℃ with a total flow rate of 50 mL·min⁻¹. -1 Palladium Pd-S2 was obtained by reducing it in a 1:4 H2:N2 mixture for 2 h to obtain a hydrotalcite-derived indium-based catalyst with an intercalated structure.

[0079] In the Pd-S2 catalyst provided in this embodiment, the mass content of Pd is 0.5 wt% and the mass content of In is 12 wt%, based on the mass of the catalyst being 100%.

[0080] (II) Pd-S2 catalyst for catalytic hydrogenation of carbon dioxide

[0081] This method is the same as the catalytic carbon dioxide hydrogenation method provided in Example 1, but the difference is that the catalyst used is a Pd-S2 catalyst, and everything else is the same as in Example 1.

[0082] The detection method for the reaction products is the same as that in Example 1, and the detection results are shown in Table 1.

[0083] Example 3

[0084] (I) Preparation of Pd-S3 catalyst

[0085] 1) Palladium nitrate hydrate, indium nitrate hydrate, zinc nitrate hexahydrate, and aluminum nitrate nonahydrate were added at a molar ratio of divalent to trivalent ions of 2:1, using deionized water as the solvent. The mixture was stirred thoroughly until completely dissolved, yielding a 100 mL, 0.45 mol / L mixed salt solution. Sodium hydroxide and sodium carbonate were prepared into a 100 mL, 1.2 mol / L mixed alkali solution, and stirred thoroughly until completely dissolved. In another beaker, 50 mL of distilled water was added, and the alkali and salt solutions were slowly added dropwise while continuously stirring. The pH of the suspension was controlled at 8 ± 0.5 using a pH meter. After all the salt solutions had been added, the suspension was transferred to a constant temperature water bath and crystallized at 70°C with continuous stirring for 5 hours. After crystallization, solid-liquid separation was performed, and the solid was washed with deionized water until neutral. The solid was then dried in a 60°C oven for 12 hours. The obtained catalyst precursor was a layered bimetallic hydroxide. The resulting solid powder was further subjected to a structural topological transformation treatment at 400℃ for 4 h, and finally at 500℃ with a total flow rate of 50 mL·min. -1 Palladium Pd-S3, a hydrotalcite-derived indium-based catalyst with an intercalated structure, was obtained by reduction in a 1:4 H2:N2 mixture for 2 h.

[0086] In the Pd-S3 catalyst provided in this embodiment, the mass content of Pd is 0.5 wt% and the mass content of In is 12 wt%, based on the mass of the catalyst being 100%.

[0087] (II) Pd-S3 catalyst for catalytic hydrogenation of carbon dioxide

[0088] This method is the same as the catalytic carbon dioxide hydrogenation method provided in Example 1, except that the catalyst used is a Pd-S3 catalyst, and everything else is the same as in Example 1.

[0089] The detection method for the reaction products is the same as that in Example 1, and the detection results are shown in Table 1.

[0090] Example 4

[0091] (I) Preparation of Pd-S4 catalyst

[0092] Indium nitrate hydrate, zinc nitrate hexahydrate, and aluminum nitrate nonahydrate were added at a molar ratio of divalent to trivalent ions of 2:1, using deionized water as the solvent. The mixture was stirred thoroughly until completely dissolved, yielding a 100 mL, 0.45 mol / L mixed salt solution. Sodium hydroxide and sodium carbonate were prepared into a 100 mL, 1.2 mol / L mixed alkali solution, and stirred thoroughly until completely dissolved. In another beaker, 50 mL of distilled water was added, and the alkali and salt solutions were slowly added dropwise while continuously stirring. The pH of the suspension was controlled at 8 ± 0.5 using a pH meter. After all the salt solutions had been added, the suspension was transferred to a constant-temperature water bath and crystallized at 70°C with continuous stirring for 5 hours. After crystallization, solid-liquid separation was performed, and the solid was washed with deionized water until neutral. The solid was then dried in a 60°C oven for 12 hours. The obtained catalyst precursor was a layered bimetallic hydroxide. The resulting solid powder was further subjected to a topological transformation treatment at 500℃ for 4 h to obtain a hydrotalcite-derived indium-based catalyst with an intercalated structure. The hydrotalcite-derived indium-based catalyst was dispersed in 100 mL of deionized water using ultrasonic assistance. 50 mL of sodium tetrachloropalladate solution (containing 0.005 g Pd) was added under magnetic stirring. The pH of the solution was then adjusted to 10 with 0.5 M sodium carbonate, followed by stirring in a 60℃ water bath for 3 h. The resulting precipitate was washed with deionized water to remove sodium ions and then vacuum dried at 60℃ for 12 h. The resulting solid powder was further subjected to a topological transformation treatment at 400℃ for 4 h, and finally dried at 500℃ with a total flow rate of 50 mL / min. -1 The catalyst was reduced in a 1:4 H2:N2 mixture for 2 h to obtain a layered structured hydrotalcite-derived indium-based catalyst supported on palladium Pd-S4.

[0093] In the Pd-S4 catalyst provided in this embodiment, the mass content of Pd is 0.5 wt% and the mass content of In is 12 wt%, based on the mass of the catalyst being 100%.

[0094] (II) Pd-S4 catalyst for catalytic hydrogenation of carbon dioxide

[0095] This method is the same as the catalytic carbon dioxide hydrogenation method provided in Example 1, except that the catalyst used is Pd-S4 catalyst, and everything else is the same as in Example 1.

[0096] The detection method for the reaction products is the same as that in Example 1, and the detection results are shown in Table 1.

[0097] Comparative Example 1

[0098] (I) Preparation of Pd-S5 based catalysts

[0099] The preparation method is the same as in Example 1, but the difference is that no structural topological transformation treatment is performed, the hydrogen pretreatment temperature is 200°C, and the resulting Pd-based catalyst is labeled as Pd-S5 catalyst.

[0100] In the Pd-S5 catalyst provided in this embodiment, the mass content of Pd is 0.5 wt% and the mass content of In is 12 wt%, based on the mass of the catalyst being 100%.

[0101] (II) Catalytic hydrogenation of carbon dioxide using Pd-S5 catalyst

[0102] This method is the same as the catalytic carbon dioxide hydrogenation method provided in Example 1, but the difference is that the catalyst used is Pd-S5 catalyst and the reaction temperature is 280℃. Everything else is the same as in Example 1.

[0103] The detection method for the reaction products is the same as that in Example 1, and the detection results are shown in Table 1.

[0104] Example 5

[0105] (I) Preparation of Pd-S6 based catalysts

[0106] The preparation method is the same as in Example 1, but the difference is that the topological transformation treatment temperature is 400°C, the hydrogen pretreatment temperature is 200°C, and the resulting Pd-based catalyst is labeled as Pd-S6 catalyst.

[0107] In the Pd-S6 catalyst provided in this embodiment, the mass content of Pd is 0.5 wt% and the mass content of In is 12 wt%, based on the mass of the catalyst being 100%.

[0108] (II) Pd-S6 catalyst for catalytic hydrogenation of carbon dioxide

[0109] This method is the same as the catalytic carbon dioxide hydrogenation method provided in Example 1, but the difference is that the catalyst used is Pd-S6 catalyst and the reaction temperature is 280℃. Everything else is the same as in Example 1.

[0110] Example 6

[0111] (I) Preparation of Pd-S7 based catalysts

[0112] The preparation method is the same as in Example 1, but the difference is that the topological transformation treatment temperature is 500°C, the hydrogen pretreatment temperature is 200°C, and the resulting Pd-based catalyst is labeled as Pd-S7 catalyst.

[0113] In the Pd-S7 catalyst provided in this embodiment, the mass content of Pd is 0.5 wt% and the mass content of In is 12 wt%, based on the mass of the catalyst being 100%.

[0114] (II) Catalytic hydrogenation of carbon dioxide using Pd-S7 catalyst

[0115] This method is the same as the catalytic carbon dioxide hydrogenation method provided in Example 1, but the difference is that the catalyst used is Pd-S7 catalyst and the reaction temperature is 280℃. Everything else is the same as in Example 1.

[0116] Example 7

[0117] (I) Preparation of Pd-S8 based catalysts

[0118] The preparation method is the same as in Example 1, but the difference is that the topological transformation treatment temperature is 600°C, the hydrogen pretreatment temperature is 200°C, and the resulting Pd-based catalyst is labeled as Pd-S8 catalyst.

[0119] In the Pd-S8 catalyst provided in this embodiment, the mass content of Pd is 0.5 wt% and the mass content of In is 12 wt%, based on the mass of the catalyst being 100%.

[0120] (II) Pd-S8 catalyst for catalytic hydrogenation of carbon dioxide

[0121] This method is the same as the catalytic carbon dioxide hydrogenation method provided in Example 1, but the difference is that the catalyst used is Pd-S8 catalyst and the reaction temperature is 280℃. Everything else is the same as in Example 1.

[0122] Example 8

[0123] (I) Preparation of Pd-S9 based catalysts

[0124] The preparation method is the same as in Example 1, but the difference is that the topological transformation treatment temperature is 700°C, the hydrogen pretreatment temperature is 200°C, and the resulting Pd-based catalyst is labeled as Pd-S9 catalyst.

[0125] In the Pd-S9 catalyst provided in this embodiment, the mass content of Pd is 0.5 wt% and the mass content of In is 12 wt%, based on the mass of the catalyst being 100%.

[0126] (II) Pd-S9 catalyst for catalytic hydrogenation of carbon dioxide

[0127] This method is the same as the catalytic carbon dioxide hydrogenation method provided in Example 1, but the difference is that the catalyst used is Pd-S9 catalyst and the reaction temperature is 280℃. Everything else is the same as in Example 1.

[0128] Example 9

[0129] (I) Preparation of Pd-S10 based catalysts

[0130] The preparation method is the same as in Example 1, but the difference is that the topological transformation treatment temperature is 800°C, the hydrogen pretreatment temperature is 200°C, and the resulting Pd-based catalyst is labeled as Pd-S10 catalyst.

[0131] In the Pd-S10 catalyst provided in this embodiment, the mass content of Pd is 0.5 wt% and the mass content of In is 12 wt%, based on the mass of the catalyst being 100%.

[0132] (II) Catalytic hydrogenation of carbon dioxide using Pd-S10 catalyst

[0133] This method is the same as the catalytic carbon dioxide hydrogenation method provided in Example 1, but the difference is that the catalyst used is Pd-S10 catalyst and the reaction temperature is 280℃. Everything else is the same as in Example 1.

[0134] Comparative Example 2

[0135] (I) Preparation of Pd-S11 based catalysts

[0136] The preparation method is the same as in Example 1, but the difference is that the topological transformation treatment temperature is 500°C and no hydrogen pretreatment is performed. The resulting Pd-based catalyst is labeled as Pd-S11 catalyst.

[0137] In the Pd-S11 catalyst provided in this embodiment, the mass content of Pd is 0.5 wt% and the mass content of In is 12 wt%, based on the mass of the catalyst being 100%.

[0138] (II) Catalytic hydrogenation of carbon dioxide using Pd-S11 catalyst

[0139] This method is the same as the catalytic carbon dioxide hydrogenation method provided in Example 1, but the difference is that the catalyst used is Pd-S11 catalyst and the reaction temperature is 280℃. Everything else is the same as in Example 1.

[0140] The detection method for the reaction products is the same as that in Example 1, and the detection results are shown in Table 1.

[0141] Example 10

[0142] (I) Preparation of Pd-S12 based catalysts

[0143] The preparation method is the same as in Example 1, but the difference is that the topological transformation treatment temperature is 500°C, the hydrogen pretreatment temperature is 100°C, and the resulting Pd-based catalyst is labeled as Pd-S12 catalyst.

[0144] In the Pd-S12 catalyst provided in this embodiment, the mass content of Pd is 0.5 wt% and the mass content of In is 12 wt%, based on the mass of the catalyst being 100%.

[0145] (II) Catalytic hydrogenation of carbon dioxide using Pd-S12 catalyst

[0146] This method is the same as the catalytic carbon dioxide hydrogenation method provided in Example 1, but the difference is that the catalyst used is Pd-S12 catalyst and the reaction temperature is 280℃. Everything else is the same as in Example 1.

[0147] The detection method for the reaction products is the same as that in Example 1, and the detection results are shown in Table 1.

[0148] Example 11

[0149] (I) Preparation of Pd-S13 based catalysts

[0150] The preparation method is the same as in Example 1, but the difference is that the topological transformation treatment temperature is 500°C, the hydrogen pretreatment temperature is 300°C, and the obtained Pd-based catalyst is labeled as Pd-S13 catalyst.

[0151] In the Pd-S13 catalyst provided in this embodiment, the mass content of Pd is 0.5 wt% and the mass content of In is 12 wt%, based on the mass of the catalyst being 100%.

[0152] (II) Catalytic hydrogenation of carbon dioxide using Pd-S13 catalyst

[0153] This method is the same as the catalytic carbon dioxide hydrogenation method provided in Example 1, but the difference is that the catalyst used is Pd-S13 catalyst and the reaction temperature is 280℃. Everything else is the same as in Example 1.

[0154] The detection method for the reaction products is the same as that in Example 1, and the detection results are shown in Table 1.

[0155] Example 12

[0156] (I) Preparation of Pd-S14 based catalysts

[0157] The preparation method is the same as in Example 1, but the difference is that the topological transformation treatment temperature is 500°C, the hydrogen pretreatment temperature is 400°C, and the obtained Pd-based catalyst is labeled as Pd-S14 catalyst.

[0158] In the Pd-S14 catalyst provided in this embodiment, the mass content of Pd is 0.5 wt% and the mass content of In is 12 wt%, based on the mass of the catalyst being 100%.

[0159] (II) Catalytic hydrogenation of carbon dioxide using Pd-S14 catalyst

[0160] This method is the same as the catalytic carbon dioxide hydrogenation method provided in Example 1, but the difference is that the catalyst used is Pd-S14 catalyst and the reaction temperature is 280℃. Everything else is the same as in Example 1.

[0161] The detection method for the reaction products is the same as that in Example 1, and the detection results are shown in Table 1.

[0162] Example 13

[0163] (I) Preparation of Pd-S15 based catalysts

[0164] The preparation method is the same as in Example 1, but the difference is that the topological transformation treatment temperature is 500°C, the hydrogen pretreatment temperature is 500°C, and the obtained Pd-based catalyst is labeled as Pd-S15 catalyst.

[0165] In the Pd-S15 catalyst provided in this embodiment, the mass content of Pd is 0.5 wt% and the mass content of In is 12 wt%, based on the mass of the catalyst being 100%.

[0166] (II) Catalytic hydrogenation of carbon dioxide using Pd-S15 catalyst

[0167] This method is the same as the catalytic carbon dioxide hydrogenation method provided in Example 1, but the difference is that the catalyst used is Pd-S15 catalyst and the reaction temperature is 280℃. Everything else is the same as in Example 1.

[0168] The detection method for the reaction products is the same as that in Example 1, and the detection results are shown in Table 1.

[0169] Example 14

[0170] (I) Preparation of Pd-S16 based catalysts

[0171] The preparation method is the same as in Example 8, and the obtained Pd-based catalyst is labeled as Pd-S16 catalyst.

[0172] In the Pd-S16 catalyst provided in this embodiment, the mass content of Pd is 0.5 wt% and the mass content of In is 1 wt%, based on the mass of the catalyst being 100%.

[0173] (II) Catalytic hydrogenation of carbon dioxide using Pd-S16 catalyst

[0174] This method is the same as the catalytic carbon dioxide hydrogenation method provided in Example 1, but the difference is that the catalyst used is Pd-S16 catalyst and the reaction temperature is 280℃. Everything else is the same as in Example 1.

[0175] The detection method for the reaction products is the same as that in Example 1, and the detection results are shown in Tables 1 and 2.

[0176] Example 15

[0177] (I) Preparation of Pd-S17 based catalysts

[0178] The preparation method is the same as in Example 8, and the obtained Pd-based catalyst is labeled as Pd-S17 catalyst.

[0179] In the Pd-S17 catalyst provided in this embodiment, the mass content of Pd is 0.5 wt% and the mass content of In is 5 wt%, based on the mass of the catalyst being 100%.

[0180] (II) Catalytic hydrogenation of carbon dioxide using Pd-S17 catalyst

[0181] This method is the same as the catalytic carbon dioxide hydrogenation method provided in Example 1, but the difference is that the catalyst used is Pd-S17 catalyst and the reaction temperature is 280℃. Everything else is the same as in Example 1.

[0182] The detection method for the reaction products is the same as that in Example 1, and the detection results are shown in Tables 1 and 2.

[0183] Example 16

[0184] (I) Preparation of Pd-S18 based catalysts

[0185] The preparation method is the same as in Example 8, and the obtained Pd-based catalyst is labeled as Pd-S18 catalyst.

[0186] In the Pd-S18 catalyst provided in this embodiment, the mass content of Pd is 0.5 wt% and the mass content of In is 10 wt%, based on the mass of the catalyst being 100%.

[0187] (II) Catalytic hydrogenation of carbon dioxide using Pd-S18 catalyst

[0188] This method is the same as the catalytic carbon dioxide hydrogenation method provided in Example 1, but the difference is that the catalyst used is Pd-S18 catalyst and the reaction temperature is 280℃. Everything else is the same as in Example 1.

[0189] The detection method for the reaction products is the same as that in Example 1, and the detection results are shown in Tables 1 and 2.

[0190] Example 17

[0191] (I) Preparation of Pd-S19 based catalysts

[0192] The preparation method is the same as in Example 8, and the obtained Pd-based catalyst is labeled as Pd-S19 catalyst.

[0193] In the Pd-S19 catalyst provided in this embodiment, the mass content of Pd is 0.5 wt% and the mass content of In is 15 wt%, based on the mass of the catalyst being 100%.

[0194] (II) Catalytic hydrogenation of carbon dioxide using Pd-S19 catalyst

[0195] This method is the same as the catalytic carbon dioxide hydrogenation method provided in Example 1, but the difference is that the catalyst used is Pd-S19 catalyst and the reaction temperature is 280℃. Everything else is the same as in Example 1.

[0196] The detection method for the reaction products is the same as that in Example 1, and the detection results are shown in Tables 1 and 2.

[0197] In this invention, 0.3 g of Pd-S19 catalyst and 0.3 g of 40-60 mesh quartz sand are weighed and uniformly mixed. The mixture is placed in a quartz reaction tube, and a hydrogen-nitrogen mixture with a total volume flow rate of 50 mL / min and a hydrogen volume concentration of 20% is introduced. The mixture is pretreated at 200°C for 2 h. After pretreatment and reduction, the H2 gas is shut off, and a leak test is performed using N2. Once no leak is confirmed, the N2 gas is shut off. A mixed reaction gas (CO / H2 = 1 / 2, V / V) is introduced and pressurized to 5 MPa, heated to 280°C, and the mixed gas flow rate is adjusted to 48 mL / min. -1 The mass hourly space velocity (MSV) of the mixed reaction gas was 9600 mL·gcat. -1 ·h -1 and 30000mL·gcat -1 ·h -1 The measured CO conversion rates were 3.02% and 1.41%, respectively. The carbon monoxide conversion rate was calculated as: (Amount of CO in the input system - Amount of CO in the post-reaction system) / Amount of CO in the input system.

[0198] Example 18

[0199] (I) Preparation of Pd-S20 based catalysts

[0200] The preparation method is the same as in Example 8, and the obtained Pd-based catalyst is labeled as Pd-S20 catalyst.

[0201] In the Pd-S20 catalyst provided in this embodiment, the mass content of Pd is 0.2 wt% and the mass content of In is 12 wt%, based on the mass of the catalyst being 100%.

[0202] (II) Pd-S20 catalyst for catalytic hydrogenation of carbon dioxide

[0203] This method is the same as the catalytic carbon dioxide hydrogenation method provided in Example 1, but the difference is that the catalyst used is Pd-S20 catalyst and the reaction temperature is 280℃. Everything else is the same as in Example 1.

[0204] The detection method for the reaction products is the same as that in Example 1, and the detection results are shown in Tables 1 and 2.

[0205] Example 19

[0206] (I) Preparation of Pd-S21 based catalysts

[0207] The preparation method is the same as in Example 8, and the obtained Pd-based catalyst is labeled as Pd-S21 catalyst.

[0208] In the Pd-S21 catalyst provided in this embodiment, the mass content of Pd is 0.4 wt% and the mass content of In is 12 wt%, based on the mass of the catalyst being 100%.

[0209] (II) Catalytic hydrogenation of carbon dioxide using Pd-S21 catalyst

[0210] This method is the same as the catalytic carbon dioxide hydrogenation method provided in Example 1, but the difference is that the catalyst used is Pd-S21 catalyst and the reaction temperature is 280℃. Everything else is the same as in Example 1.

[0211] The detection method for the reaction products is the same as that in Example 1, and the detection results are shown in Tables 1 and 2.

[0212] Example 20

[0213] (I) Preparation of Pd-S22-based catalysts

[0214] The preparation method is the same as in Example 8, and the obtained Pd-based catalyst is labeled as Pd-S22 catalyst.

[0215] In the Pd-S22 catalyst provided in this embodiment, the mass content of Pd is 0.8 wt% and the mass content of In is 12 wt%, based on the mass of the catalyst being 100%.

[0216] (II) Catalytic hydrogenation of carbon dioxide using Pd-S22 catalyst

[0217] This method is the same as the catalytic carbon dioxide hydrogenation method provided in Example 1, but the difference is that the catalyst used is Pd-S22 catalyst and the reaction temperature is 280℃. Everything else is the same as in Example 1.

[0218] The detection method for the reaction products is the same as that in Example 1, and the detection results are shown in Tables 1 and 2.

[0219] Example 21

[0220] (I) Preparation of Pd-S23-based catalysts

[0221] The preparation method is the same as in Example 8, and the obtained Pd-based catalyst is labeled as Pd-S23 catalyst.

[0222] In the Pd-S23 catalyst provided in this embodiment, the mass content of Pd is 1.6 wt% and the mass content of In is 12 wt%, based on the mass of the catalyst being 100%.

[0223] (II) Catalytic hydrogenation of carbon dioxide using Pd-S23 catalyst

[0224] This method is the same as the catalytic carbon dioxide hydrogenation method provided in Example 1, but the difference is that the catalyst used is Pd-S23 catalyst and the reaction temperature is 280℃. Everything else is the same as in Example 1.

[0225] The detection method for the reaction products is the same as that in Example 1, and the detection results are shown in Tables 1 and 2.

[0226] Comparative Example 3

[0227] (I) Preparation of Pd-S24 catalyst

[0228] This comparative example provides a zinc-aluminum catalyst with hydrotalcite as a precursor, supported by precipitation of palladium, denoted as Pd-S24. The specific preparation method of this catalyst is as follows:

[0229] Zinc nitrate hexahydrate and aluminum nitrate nonahydrate were added at a molar ratio of divalent zinc ions to trivalent aluminum ions of 3:1, using deionized water as the solvent. The mixture was stirred thoroughly until completely dissolved, yielding a 100 mL, 0.45 mol / L mixed salt solution. Sodium hydroxide and sodium carbonate were prepared into a 100 mL, 1.2 mol / L mixed alkali solution, and stirred thoroughly until completely dissolved. In another beaker, 50 mL of distilled water was added, and the alkali and salt solutions were slowly added dropwise while continuously stirring. The pH of the suspension was controlled at 8 ± 0.5 using a pH meter. After all the salt solutions had been added, the suspension was transferred to a constant-temperature water bath and crystallized at 70°C with continuous stirring for 5 hours. After crystallization, solid-liquid separation was performed, and the solid was washed with deionized water until neutral. The solid was then dried in a 60°C oven for 12 hours. The obtained catalyst precursor was a layered bimetallic hydroxide. The resulting solid powder was further subjected to a topological transformation treatment at 500℃ for 4 h to obtain a hydrotalcite-derived zinc-aluminum catalyst with an intercalated structure. The hydrotalcite-derived zinc-aluminum catalyst was dispersed in 100 mL of deionized water using ultrasonic assistance. 50 mL of palladium nitrate solution (containing 0.005 g Pd) was added under magnetic stirring. The pH of the solution was then adjusted to 10 with 0.5 M sodium carbonate, followed by stirring in a 60℃ water bath for 3 h. The resulting precipitate was washed with deionized water to remove sodium ions and then vacuum dried at 60℃ for 12 h. The resulting solid powder was further subjected to a topological transformation treatment at 600℃ for 4 h, and finally dried at 200℃ with a total flow rate of 50 mL / min. -1 The catalyst was reduced in a 1:4 H2:N2 mixture for 2 h to obtain a layered double hydroxide-derived zinc-aluminum catalyst supported on palladium Pd-S24.

[0230] In the Pd-S24 catalyst provided in this comparative example, the mass content of Pd is 0.5 wt% and the mass content of In is 0 wt%, based on the mass of the catalyst as 100%.

[0231] (II) Pd-S24 catalyst for catalytic hydrogenation of carbon dioxide

[0232] This method is the same as the catalytic carbon dioxide hydrogenation method provided in Example 1, except that the catalyst used is the Pd-S24 catalyst provided in this comparative example, and the reaction temperature is 280℃. Everything else is the same as in Example 1.

[0233] The detection method for the reaction products is the same as that in Example 1, and the detection results are shown in Tables 1 and 2.

[0234] Example 22

[0235] (I) Preparation of S25 catalyst

[0236] This embodiment provides a hydrotalcite-derived indium-based catalyst with an intercalated structure, denoted as S25. The specific preparation method of this catalyst is as follows:

[0237] Indium nitrate hydrate, zinc nitrate hexahydrate, and aluminum nitrate nonahydrate were added at a molar ratio of divalent to trivalent ions of 2:1, using deionized water as the solvent. The mixture was stirred thoroughly until completely dissolved, yielding a 100 mL, 0.45 mol / L mixed salt solution. Sodium hydroxide and sodium carbonate were prepared into a 100 mL, 1.2 mol / L mixed alkali solution, and stirred thoroughly until completely dissolved. In another beaker, 50 mL of distilled water was added, and the alkali and salt solutions were slowly added dropwise while continuously stirring. The pH of the suspension was controlled at 8 ± 0.5 using a pH meter. After all the salt solutions had been added, the suspension was transferred to a constant-temperature water bath and crystallized at 70°C with continuous stirring for 5 hours. After crystallization, solid-liquid separation was performed, and the solid was washed with deionized water until neutral. The solid was then dried in a 60°C oven for 12 hours. The obtained catalyst precursor was a layered bimetallic hydroxide. The resulting solid powder was further subjected to a topological transformation treatment at 500℃ for 4 h at 200℃ with a total flow rate of 50 mL / min. -1 The catalyst was reduced in a 1:4 H2:N2 mixture for 2 h to obtain a hydrotalcite-derived indium-based catalyst with an intercalated structure.

[0238] In the S25 catalyst provided in this embodiment, the mass content of Pd is 0 wt% and the mass content of In is 12 wt%, based on the mass of the catalyst being 100%.

[0239] (ii) S25 catalyst for catalytic hydrogenation of carbon dioxide

[0240] This method is the same as the catalytic carbon dioxide hydrogenation method provided in Example 1, except that the catalyst used is the S25 catalyst provided in this example, and the reaction temperature is 280℃. Everything else is the same as in Example 1.

[0241] The detection method for the reaction products is the same as that in Example 1, and the detection results are shown in Tables 1 and 2.

[0242] Table 1

[0243]

[0244] Table 2

[0245]

[0246]

[0247]

[0248] Wherein, carbon dioxide conversion rate = (amount of CO2 in the input system - amount of CO2 in the system after the reaction) / amount of CO2 in the input system;

[0249] Methanol selectivity = Methanol production / CO2 consumption;

[0250] Methanol space-time yield = Methanol production / (time × volume);

[0251] By comparing the carbon dioxide conversion rate and methanol space-time yield in Table 1, it is shown that palladium-based catalysts prepared by different methods exhibit varying performance in the reaction of carbon dioxide hydrogenation to methanol. Furthermore, the palladium source, structural topological transformation, and pretreatment temperature also influence the reaction performance. The hydrotalcite-derived copper-based catalysts prepared by different methods not only effectively control the elemental composition ratio but also allow for controllable structural topological transformation parameters. Therefore, supported palladium-based catalysts possessing both high dispersion of the active component palladium and tunable electronic properties of the metal-support interface structure are obtained.

[0252] Figure 1 In the diagram, a1 is a TEM image of the catalyst prepared in Comparative Example 3, a2 is an HRTEM image of the catalyst prepared in Comparative Example 3, and a3 and a4 are fast Fourier transform images of the catalyst prepared in Comparative Example 3.

[0253] Figure 1 In the image, b1 is a TEM image of the catalyst prepared in Example 14, b2 is an HRTEM image of the catalyst prepared in Example 14, and b3 and b4 are fast Fourier transform images of the catalyst prepared in Example 14.

[0254] Figure 1 In the image, c1 is a TEM image of the catalyst prepared in Example 15, c2 is an HRTEM image of the catalyst prepared in Example 15, and c3 and c4 are fast Fourier transform images of the catalyst prepared in Example 15.

[0255] Figure 1 In the image, d1 is a TEM image of the catalyst prepared in Example 16, d2 is an HRTEM image of the catalyst prepared in Example 16, and d3 and d4 are fast Fourier transform images of the catalyst prepared in Example 16.

[0256] Figure 1 In the image, e1 is a TEM image of the catalyst prepared in Example 17, e2 is an HRTEM image of the catalyst prepared in Example 17, and e3 and e4 are fast Fourier transform images of the catalyst prepared in Example 17.

[0257] from Figure 1It can be seen that the catalyst in Comparative Example 3 has a relatively complete lamellar structure with clear edges. With increasing In content, the lamellar structure of the catalyst gradually breaks down, but some lamellar structures are still visible. ZnO(101) and ZnO(100) crystal planes were observed in HRTEM and Fast Fourier Transform images, while lattice fringes of ZnO(101) and In2O3(222) crystal planes were observed on the catalysts of Examples 14-17. Due to the low loading and good dispersibility, no Pd-related lattice fringes were found in the figures. This figure demonstrates that catalysts with different In contents formed indium oxide and zinc oxide after structural topological transformation and reduction, and although the structure partially collapsed, it still retained a lamellar structure.

[0258] Figure 2 In Example 22, a1 is a TEM image of the hydrotalcite-derived indium catalyst, a2 is an HRTEM image of the hydrotalcite-derived indium catalyst, and a3 and a4 are fast Fourier transform images of the catalyst prepared in Example 22.

[0259] Figure 2 b1 is a TEM image of the supported palladium catalyst prepared in Example 18, b2 is an HRTEM image of the supported palladium catalyst prepared in Example 18, and b3 and b4 are fast Fourier transform images of the catalyst prepared in Example 18.

[0260] Figure 2 c1 is a TEM image of the supported palladium catalyst prepared in Example 19, c2 is an HRTEM image of the supported palladium catalyst prepared in Example 19, and c3 and c4 are fast Fourier transform images of the catalyst prepared in Example 19.

[0261] Figure 2 In the image, d1 is a TEM image of the supported palladium catalyst prepared in Example 20, d2 is an HRTEM image of the supported palladium catalyst prepared in Example 20, and d3 and d4 are fast Fourier transform images of the catalyst prepared in Example 20.

[0262] Figure 2 In the image, e1 is a TEM image of the supported palladium catalyst prepared in Example 21, e2 is an HRTEM image of the supported palladium catalyst prepared in Example 21, and e3 and e4 are fast Fourier transform images of the catalyst prepared in Example 21.

[0263] Figure 2The catalyst in Example 22 is shown to be formed by the stacking of many broken lamellar structures. The catalysts in Examples 18-21, after being loaded with Pd, still maintained their lamellar structures, indicating that Pd retains its lamellar structure even after being added to the InZnAl support. In HRTEM and Fast Fourier Transform images, lattice fringes of ~0.24 nm and ~0.28 nm were observed on all catalysts, corresponding to the ZnO(101) and In2O3(222) crystal planes, respectively. This figure demonstrates that catalysts with different In contents formed indium oxide and zinc oxide after structural topological transformation and reduction, while still retaining their lamellar structures.

[0264] Figure 3 Curve-1 InZnAl-LDH corresponds to the XRD pattern of the catalyst prepared in Example 14, curve-5 InZnAl-LDH corresponds to the XRD pattern of the catalyst prepared in Example 15, curve-10 InZnAl-LDH corresponds to the XRD pattern of the catalyst prepared in Example 16, and curve-15 InZnAl-LDH corresponds to the XRD pattern of the catalyst prepared in Example 17. Figure 3 It can be seen that characteristic peaks of the (003), (006), and (012) crystal planes of hydrotalcite appeared at 2θ of 11.6°, 23.4°, and 34.9°, indicating the synthesis of ZnAl-LDH and InZnAl-LDH hydrotalcite. When the In content reached 15 wt.%, in addition to the characteristic peaks of hydrotalcite, some new characteristic peaks appeared, which belonged to In(OH)3, indicating that some In did not enter the hydrotalcite layers. This figure proves that the precursor formed by different In contents is a hydrotalcite structure.

[0265] As can be seen from the above embodiments, the present invention provides a method for preparing a hydrotalcite-derived indium-based catalyst, comprising the following steps: [The text abruptly ends here, so the translation stops as well.] 3+ Indium salts, Zn 2+ Zinc salts, Al 3+Aluminum salts and water are mixed to obtain a mixed salt solution; an alkaline compound containing hydroxide ions and / or a carbonate are mixed to obtain an alkaline solution; the alkaline solution and the mixed salt solution are added dropwise to water, controlling the pH of the suspension to be 7-14. After the mixed salt solution is added, the suspension is liquidized, and solid-liquid separation is performed. The obtained solid is washed to neutral, dried, and a layered bimetallic hydroxide is obtained. This is then subjected to structural topological transformation treatment and reduction to obtain a hydrotalcite-derived indium-based catalyst. The method for preparing palladium-supported hydrotalcite-derived indium-based catalysts of this invention uses indium salts, zinc salts, and aluminum salts as raw materials, and alkaline compounds containing hydroxide ions and / or carbonates as precipitants. A constant pH method is used to obtain the hydrotalcite-derived indium-based catalyst; subsequently, palladium-supported hydrotalcite-derived indium-based catalysts are obtained through impregnation, precipitation, and constant pH methods. Furthermore, the effects of different structural topological transformation processes, pretreatment temperature, and the contents of Pd and In on the reaction performance were explored. The preparation method described in this invention utilizes the tunable metal elements in hydrotalcite, achieving high metal dispersion and maintaining the intercalation structure after structural topological transformation, thereby enabling the microstructure control of indium, zinc, and aluminum in indium-based catalysts. Furthermore, the palladium prepared by this method exhibits good dispersion and tunable electronic properties of the metal-support interface structure, demonstrating excellent catalytic performance when used in the carbon monoxide / carbon dioxide hydrogenation reaction. Experimental results show that different preparation methods affect reaction performance; the precipitation method, although having a lower conversion rate, offers the highest methanol selectivity. Different palladium sources have varying effects on carbon dioxide conversion and methanol selectivity. Moreover, exploring catalyst performance using different structural topological transformation temperatures and reduction temperatures reveals that the pretreatment process influences reaction performance. After selecting the optimal pretreatment and adjusting the valence, different In contents were investigated to explore their impact on reaction performance. Results showed that when the In content was 10 wt%, the reaction performance was optimal, superior to the control example PdZnAl, with a STY reaching 41.64 g / (g). Pd •h). As the Pd content increases, the carbon dioxide conversion rate increases, while the methanol selectivity first increases and then decreases.

[0266] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing an indium-based catalyst derived from hydrotalcite, comprising the following steps: In 3+ dium salt, a zinc salt of Zn 2+ , an aluminum salt of Al 3+ , and water to obtain a mixed salt solution; mixing a hydroxyl group-containing basic compound and / or a carbonate to obtain a base solution; dropping an alkali solution and a mixed salt solution into water, controlling the pH of the suspension to be 7-14, crystallizing the suspension after the dropping of the mixed salt solution is completed, separating the solid from the liquid, washing the obtained solid to neutral, drying, obtaining a layered double hydroxide, and then performing a structure topology transformation treatment and reduction to obtain the indium-based catalyst derived from hydrotalcite.

2. A method for preparing a palladium-loaded indium-based catalyst derived from hydrotalcite, comprising the following steps: immersing or precipitating the indium-based catalyst derived from hydrotalcite not reduced in claim 1 with a palladium salt, and then performing a structure topology transformation treatment and reduction to obtain the palladium-loaded indium-based catalyst derived from hydrotalcite.

3. The preparation method according to claim 2, characterized in that, The precipitating of the indium-based catalyst derived from hydrotalcite with a palladium salt comprises: The hydrotalcite-derived indium-based catalyst is dispersed in deionized water, a solution containing Pd 2+ is added under stirring, and the pH is adjusted to 8-11. The mixture is stirred in a water bath at 40-100°C for 1-12 h. The obtained precipitate is washed and dried, and then subjected to structure topology transformation treatment and reduction to obtain a hydrotalcite-derived indium-based catalyst loaded with palladium.

4. The preparation method according to claim 2, characterized in that, The immersing of the indium-based catalyst derived from hydrotalcite with a palladium salt comprises: A solution of a palladium salt containing Pd 2+ is added dropwise to an unreduced hydrotalcite-derived indium-based catalyst, stirred at 10-35°C for 1-12 h, vacuum dried, and then subjected to a structure topology transformation treatment and reduction to obtain a hydrotalcite-derived indium-based supported palladium catalyst.

5. A method for preparing a palladium-loaded indium-based catalyst derived from hydrotalcite, comprising the following steps: a palladium salt containing Pd 2+ , an indium salt containing In 3+ , a zinc salt containing Zn 2+ , an aluminum salt containing Al 3+ and water to obtain a mixed salt solution; and mixing a hydroxyl-containing basic compound and / or a carbonate to prepare a base solution; dropping an alkali solution and a mixed salt solution into water, controlling the pH of the suspension to be 7-14, crystallizing the suspension after the dropping of the mixed salt solution is completed, separating the solid from the liquid, washing the obtained solid to neutral, drying, obtaining a layered double hydroxide, and then performing a structure topology transformation treatment and reduction to obtain the palladium-loaded indium-based catalyst derived from hydrotalcite.

6. The production method according to claim 1, 2 or 5, characterized by, The temperature for the crystallization is 40-100℃, and the time for the crystallization is 1-12h; The atmosphere for the structure topology transformation treatment is selected from one or more of vacuum, nitrogen, argon, helium, air, and hydrogen, the temperature for the structure topology transformation treatment is 400-800℃, and the time for the structure topology transformation treatment is 2-6h; The reduction is performed by using hydrogen, the temperature for the reduction is 100-500℃, and the time for the reduction is 2-6h.

7. The production method according to claim 1, 2 or 5, characterized by, Zn 2+ With Al 3+ The molar ratio is (1~4):1; Zn 2+ With Al 3+ The sum of their molar concentrations is 0.1~1 mol / L; In 3+ a molar concentration of 0.0001 to 1 mol / L; In 3+ with Al 3+ in a molar ratio of (1-1000): 1000.

8. The production method according to claim 2 or 5, characterized by, The loading amount of palladium in the palladium-loaded indium-based catalyst derived from hydrotalcite is 0.01-3wt.%.

9. The production method according to claim 1, 2 or 5, characterized by, The alkali compound containing hydroxyl ions is selected from sodium hydroxide or potassium hydroxide; and the carbonate is selected from sodium carbonate or potassium carbonate. The molar ratio of the alkali compound containing hydroxyl ions to the carbonate is (1-5):

1. The sum of the molar concentrations of the alkali compound containing hydroxyl ions and the carbonate is 0.1-5 mol / L. The volume ratio of the mixed salt solution to the alkali solution is (0.1-5):

1. The molar concentration of the carbonate in the alkali solution is 0.1-1 mol / L. The molar concentration of the alkali compound containing hydroxyl ions in the alkali solution is 0.1-4 mol / L.

10. The use of the indium-based catalyst derived from hydrotalcite prepared by the method in claim 1 or the palladium-loaded indium-based catalyst derived from hydrotalcite prepared by the method in any one of claims 2-9 in the hydrogenation of CO or CO2 to methanol. Reaction conditions for the production of methanol include: The reaction temperature is 180-300℃; the reaction pressure is 0.1-10 MPa; the volume ratio of H2:CO or CO2 in the reaction mixed gas is 1-6; the mass space velocity is 9000-40000 mL·g cat -1 ·h -1 ; the volume flow rate of the mixed gas of CO or CO2 and H2 is 10-200 mL / min; and the mixed gas balance gas is selected from one or more of nitrogen, argon and helium.

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