Preparation method of supported high-entropy metal oxide catalyst for hydrogen production by photo-thermal methanol-water reforming

Abstract

The invention discloses a preparation method of a supported high-entropy metal oxide catalyst for photo-thermal methanol-water reforming hydrogen production. The preparation method is specifically implemented according to the following steps: step 1, preparing CeO2 gel; step 2, grinding the CeO2 gel obtained in the step 1 serving as a raw material to obtain CeO2 gel powder, and calcining the CeO2 gel powder to obtain a porous sheet CeO2 oxide; step 3, loading a plurality of metal ions on the porous sheet CeO2 oxide obtained in the step 2 to prepare multi-metal loaded CeO2 powder; and 4, calcining the multi-metal loaded CeO2 powder obtained in the step 3, and grinding to obtain the loaded high-entropy metal oxide catalyst. The problems of slow reaction kinetics, long activation time and low hydrogen production efficiency of the existing low-temperature methanol-water reforming hydrogen production catalyst in a temperature interval of lower than 150 DEG C are solved.

Description

Technical Field

[0001] This invention belongs to the field of catalyst preparation technology, specifically relating to a method for preparing a supported high-entropy metal oxide catalyst for photothermal methanol-water reforming to produce hydrogen. Background Technology

[0002] Hydrogen energy boasts significant advantages such as high energy density, green and low-carbon characteristics, and wide applicability. Although hydrogen energy development and utilization technologies, represented by fuel cells, have achieved major breakthroughs in recent years and are rapidly developing in transportation, energy storage, and industry, the flammable and explosive nature of hydrogen (H2) and its high liquefaction pressure (up to 700 psi) pose significant challenges to the cost, safety, and reliability of its storage and transportation. Compared to liquid organic hydrogen storage materials such as methylcyclohexane, dibenzyltoluene, and carbazole, methanol (CH3OH) has significant economic advantages: low cost and wide availability. Its mass hydrogen storage density can reach 18.8%, and it can release three times the equivalent of hydrogen through water reforming (CH3OH + H2O → CO2 + 3H2). Combined with mature and safe methanol storage and transportation technologies, it becomes a highly promising liquid hydrogen storage carrier. While traditional methanol steam reforming (SRM) hydrogen production technology is widely used, it requires high temperature (250~400 ℃) and high pressure, and its catalytic performance is sensitive to operating conditions. Gas-phase reactions result in high energy consumption and equipment requirements. High temperatures also exacerbate methanol decomposition and reverse water-gas shift reactions, producing CO as a byproduct and reducing hydrogen purity, making it difficult to meet the needs of distributed or mobile hydrogen production fuel cells. In contrast, aqueous methanol reforming (APRM) hydrogen production technology eliminates the need for a liquid vaporization unit, enabling the construction of compact, integrated online hydrogen production devices that meet miniaturization and space requirements. The liquid-phase environment also enhances the water-gas shift reaction, effectively suppressing CO generation. Therefore, developing efficient APRM technology under mild conditions has become a key research focus for modular, distributed hydrogen production systems. However, the main bottleneck of existing low-temperature APRM hydrogen production technologies lies in their extremely low activity below 150 °C. According to the basic principles of thermocatalysis, low temperatures limit charge transfer between the catalyst and molecules, molecular activation rates, and adsorption / desorption processes, leading to slow reaction kinetics, long activation times, and low hydrogen production efficiency. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing a supported high-entropy metal oxide catalyst for photothermal methanol-water reforming to produce hydrogen, thereby solving the problems of slow reaction kinetics, long activation time, and low hydrogen production efficiency of existing low-temperature methanol-water reforming hydrogen production catalysts in the temperature range below 150 °C.

[0004] To address the aforementioned technical problems, this invention provides a method for preparing a supported high-entropy metal oxide catalyst for photothermal methanol-water reforming to produce hydrogen, specifically implemented according to the following steps:

[0005] Step 1, prepare CeO2 gel;

[0006] Step 2: Using the CeO2 gel obtained in Step 1 as raw material, first grind it to obtain CeO2 gel powder, and then calcine the CeO2 gel powder to obtain porous thin sheet CeO2 oxide.

[0007] Step 3: Load various metal ions onto the porous CeO2 oxide sheets obtained in Step 2 to prepare multi-metal-loaded CeO2 powder;

[0008] Step 4: Calcination treatment is performed on the multi-metal supported CeO2 powder obtained in Step 3. After grinding, a supported high-entropy metal oxide catalyst is obtained.

[0009] The technical solution of the present invention also has the following characteristics:

[0010] As a preferred embodiment of the present invention, in step 1, the preparation of CeO2 gel specifically involves:

[0011] Step 1.1: Add polyvinylpyrrolidone to deionized water and allow it to dissolve completely;

[0012] Step 1.2: Add cerium nitrate to the solution obtained in step 1.1. After it is completely dissolved, heat it to 60-100℃ until the solution is completely evaporated to obtain solid gel crystals, namely CeO2 gel; wherein each 10 mmol of cerium nitrate corresponds to 2-10 g of polyvinylpyrrolidone.

[0013] As a preferred embodiment of the present invention, step 2 is specifically implemented according to the following steps:

[0014] Step 2.1: Place the solid gel crystal block obtained in step 1.2 into a ball mill and ball mill it to obtain a uniform porous carrier gel powder;

[0015] Step 2.2: Place the porous carrier gel powder obtained in Step 2.1 in a ceramic boat, cover the surface with tin foil, and punch holes in the tin foil. Calcinate the powder in air at a heating rate of 1-7 ℃ / min to 400-800 ℃ for 2-8 h to obtain porous CeO2 oxide sheets.

[0016] As a preferred embodiment of the present invention, step 3 specifically comprises:

[0017] The porous CeO2 oxide obtained in step 2 is added to deionized water and completely dispersed. Then, any 5-7 metal salts selected from manganese nitrate, cobalt nitrate, iron nitrate, copper nitrate, palladium nitrate, nickel nitrate, zirconium nitrate, cadmium nitrate, and zinc nitrate are added and completely dissolved. The solution is then heated to 60-100 °C until it is completely evaporated. After grinding, a multi-metal loaded powder is obtained. The total molar ratio of the porous CeO2 oxide to the selected metal salt is 1:0.1-1.

[0018] As a preferred technical solution of the present invention, step 4 specifically involves: placing the multi-metal supported CeO2 powder obtained in step 3 in a ceramic boat, covering the surface with tin foil, and punching holes in the tin foil. Then, calcining the powder at a heating rate of 1-7℃ / min to 400-800℃ in an air atmosphere for 2-8 hours. After grinding, a supported high-entropy metal oxide catalyst is obtained.

[0019] The beneficial effects of this invention are:

[0020] (1) The catalyst obtained by the preparation method of the supported high-entropy metal oxide catalyst for photothermal methanol-water reforming hydrogen production of the present invention can achieve uniform distribution of low-temperature catalytic active metals (such as Zr, Mn, Ti, V), photothermal conversion metals (such as Mn, Co) and hydrogen production co-catalytic metals (such as Fe, Cu, Ni, Cr, Zn, Pd) on CeO2 porous sheets. Its crystal composition shows the single crystal structure of CeO2, which is beneficial to the mutual coupling of multi-metal active sites during the catalytic process.

[0021] (2) The preparation method of the supported high-entropy metal oxide catalyst for photothermal methanol-water reforming hydrogen production of the present invention is simple, low-cost, has good catalyst stability, and is easy to prepare on a large scale. Attached Figure Description

[0022] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0023] Figure 1 These are TEM images of the products obtained in Example 1 and the comparative sample;

[0024] Figure 2 These are BET graphs of the products obtained in Example 1 and the comparative sample;

[0025] Figure 3 These are pore size distribution diagrams of the products obtained in Example 1 and the comparative sample.

[0026] Figure 4 This is a graph showing the activity of hydrogen production from low-temperature photothermal methanol-water reforming using different proportions of comparative samples from Example 1.

[0027] Figure 5 This is the activity diagram of low-temperature methanol-water reforming for hydrogen production under three conditions: photocatalysis, thermal catalysis, and photothermal synergistic catalysis, as shown in Example 1.

[0028] Figure 6 These are XRD patterns of the products obtained in Examples 1, 2, and 3;

[0029] Figure 7 This is a mapping diagram of the product obtained in Example 1;

[0030] Figure 8 This is a low-temperature photothermal methanol-water reforming hydrogen production activity diagram of the products obtained in Examples 1, 2, 3, and 4. Detailed Implementation

[0031] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] The present invention discloses a method for preparing a supported high-entropy metal oxide catalyst for photothermal methanol-water reforming to produce hydrogen, which is specifically implemented according to the following steps:

[0033] Step 1, preparing CeO2 gel, specifically:

[0034] Step 1.1: Add polyvinylpyrrolidone (PVP, K30, molecular weight 40000) to deionized water and dissolve it completely.

[0035] Step 1.2: Add cerium nitrate (Ce(NO3)2·6H2O) to the solution obtained in Step 1.1. After it is completely dissolved, heat it to 60-100 °C until the solution is completely evaporated to obtain solid gel crystals, i.e., CeO2 gel; wherein each 10 mmol of cerium nitrate (Ce(NO3)2·6H2O) corresponds to 2-10 g of polyvinylpyrrolidone.

[0036] Step 2: Using the CeO2 gel obtained in Step 1 as raw material, prepare porous thin-sheet CeO2 oxide, specifically as follows:

[0037] Step 2.1: Place the CeO2 gel block obtained in step 1.2 into a ball mill and ball mill it to obtain a uniform porous carrier gel powder;

[0038] Step 2.2: Place the porous carrier gel powder obtained in step 2.1 in a ceramic boat, cover the surface with tin foil, and punch holes in the tin foil. Calcine the powder in air at a heating rate of 1-7 ℃ / min to 400-800 ℃ for 2-8 h to obtain porous sheet CeO2 oxide.

[0039] Step 3: Add the porous CeO2 oxide flakes obtained in Step 2 to deionized water and disperse it completely. Then, add any 5-7 metal salts selected from manganese nitrate (Mn(NO3)2·4H2O), cobalt nitrate (Co(NO3)2·6H2O), iron nitrate (Fe(NO3)2·9H2O), copper nitrate (Cu(NO3)2·3H2O), palladium nitrate (Pb(NO3)2), nickel nitrate (Ni(NO3)2·6H2O), zirconium nitrate (Zr(NO3)2·5H2O), cadmium nitrate (Cd(NO3)3·4H2O), and zinc nitrate (Zn(NO3)2·6H2O) and dissolve them completely. Then heat to 60-100 °C until the solution is completely evaporated. After grinding, obtain multi-metal supported CeO2 powder; wherein the total molar ratio of porous CeO2 oxide flakes to the selected metal salts is 1:0.1-0.5.

[0040] Step 4: Place the multi-metal supported CeO2 powder obtained in Step 3 in a ceramic boat, cover the surface with tin foil, and punch holes in the tin foil. Calcinate the powder in air at a heating rate of 1-7 °C / min to 400-800 °C for 2-8 h. After grinding, the supported high-entropy metal oxide catalyst is obtained.

[0041] The principle of this invention is as follows: on the one hand, it utilizes semiconductor photocatalytic materials to generate highly active photogenerated carriers upon photoexcitation; on the other hand, it combines an external low-temperature heat source to promote the dissociation and activation of methanol C-H bonds and water molecule O-H bonds through the coupling effect of photoexcitation and thermal excitation. CeO2 metal oxide is selected as the active photocatalyst support unit, satisfying the structural basis for molecular activation using photogenerated carriers. High-entropy oxide-modified support units are formed using multi-metal synergy, with transition metals such as Ni, Cu, and Co, and noble metals such as Pt, Pd, and Ru as surface-active metal units. Through charge transfer of photogenerated carriers and the energy guarantee of the external low-temperature heat source, the thermocatalytic process of subsequent intermediate molecule adsorption and conversion is further enhanced. This achieves the rational assembly of photocatalytic and thermocatalytic units in different elementary reactions of APRM hydrogen production, complementing each other's strengths and weaknesses, effectively leveraging the photo-thermal catalytic synergy, and achieving highly efficient low-temperature photothermal coupled catalytic APRM hydrogen production activity. Therefore, the purpose of this invention is to provide a method for preparing a highly efficient hydrogen production catalyst that can be used under low-temperature methanol-water reforming conditions. Currently, research on low-temperature photothermal catalytic APRM hydrogen production technology is still relatively scarce. It is a novel low-temperature methanol-water reforming hydrogen production technology.

[0042] This invention provides a method for preparing a supported high-entropy metal oxide catalyst for photothermal methanol-water reforming to produce hydrogen. The catalyst is prepared via a sol-gel method followed by ball milling and calcination. First, polyvinylpyrrolidone (PVP), with its long-chain organic molecular structure, is used as an ion-complexing agent to achieve uniform cross-linking between cerium dioxide crystal grains. Second, a high-speed ball mill can pulverize large gel crystals into ultrafine gel powder, effectively reducing grain size and ensuring uniform crystallization during calcination. Subsequent high-temperature calcination leads to the thermal decomposition of the organic cross-linked structure, forming a rich and uniform mesoporous structure, which serves as a support for the uniform loading of multiple metals. Finally, the prepared porous CeO2 sheet support has an electronegative surface. During stirring and heating until the solution is completely evaporated, different metal ions can be uniformly and efficiently adsorbed onto the porous sheet support through electrostatic adsorption. The multi-metal loaded powder then undergoes a high-temperature calcination process in an air atmosphere to achieve the crystallization transformation of surface multi-metal ions into high-entropy metal oxides. Due to the highly uniform distribution of different metal ions, the prepared supported high-entropy metal oxides have a unique single-crystal structure, achieving a uniform distribution of low-temperature catalytically active metals (such as Ce and Mn), photothermal conversion metals (such as Cu, Zr, and Co), and hydrogen production co-catalytic metals (such as Fe, Pd, Ni, Cr, and Zn) at the atomic level.

[0043] Based on the above characteristics, the supported high-entropy metal oxide catalyst obtained in this invention possesses abundant active sites, excellent crystal structure stability, and a well-developed mesoporous structure. Its abundant multi-metal active sites can promote the dissociation and activation of methanol C-H bonds and water molecule O-H bonds, accelerating the dehydrogenation reaction. Simultaneously, the prepared supported high-entropy metal oxide can generate active photogenerated carriers under light irradiation. Photothermal synergistic catalysis accelerates charge transfer, adsorption state generation, and changes between multi-site active units and reactant molecules during the reaction process, promoting the formation of reaction intermediates. Furthermore, this catalyst is a black catalytic material with excellent surface photothermal conversion performance. Compared to traditional methanol steam reforming hydrogen production technology, which requires high temperature (250~400 ℃) and high pressure, and whose catalytic performance is highly sensitive to operating conditions, the gas-phase reaction results in relatively high energy consumption and equipment requirements. The preparation of the supported high-entropy metal oxide catalyst provided by this invention enables methanol aqueous reforming (APRM) hydrogen production technology to achieve efficient hydrogen production at low temperature (120~250 ℃), which helps to solve the problem of green and low-carbon methanol aqueous reforming online hydrogen production and plays an important supporting role in promoting the development of modular and distributed hydrogen production systems and hydrogen energy applications.

[0044] Furthermore, the supported high-entropy metal oxide catalyst obtained by this invention is characterized by its excellent photothermal conversion efficiency and photothermal catalytic activity, and its catalytic performance can be changed by regulating the metal composition. Based on this, the catalyst can also be used in various application scenarios such as photothermal catalytic CO2 reduction, CH4 conversion, and reductive denitrification.

[0045] Example 1

[0046] The present invention discloses a method for preparing a supported high-entropy metal oxide catalyst for photothermal methanol-water reforming to produce hydrogen, which is specifically implemented according to the following steps:

[0047] Step 1: Preparation of CeO2 gel; specifically:

[0048] Step 1.1: Add 100 mL of deionized water to a beaker, add 5 g of polyvinylpyrrolidone (PVP) as an ion complexing agent, and stir with a magnetic stirrer for 30 min to dissolve it.

[0049] Step 1.2: Add 10 mmol of Ce(NO3)2·6H2O to the solution obtained in Step 1.1 and stir continuously for 60 min to completely dissolve it; then heat the solution to 100 °C and keep stirring until the solution is completely evaporated to obtain solid gel crystals, namely CeO2 gel.

[0050] Step 2: Preparation of porous CeO2 oxide sheets; specifically:

[0051] Step 2.1: Place the solid gel crystal block obtained in step 1.2 into a high-speed ball mill and ball mill it at a speed of 1000 rpm for 1 h to obtain uniform CeO2 gel powder.

[0052] Step 2.2: Place the CeO2 gel powder obtained in Step 1 in a ceramic boat, cover the surface with tin foil, and punch holes in the tin foil. Calcinate the powder in air at a heating rate of 1 °C / min to 400 °C for 7 h. The resulting porous CeO2 oxide sheet is labeled as CeO2 PS.

[0053] Step 3: Prepare CeO2-supported Cu, Co, Ni, Zr, and Pd metal powders; specifically:

[0054] Add 100 ml of deionized water to a beaker, and add 2 mmol of CeO2 oxide obtained in step 2 as a carrier under stirring. Stir continuously for 30 min to completely disperse the oxide. Then add a total of 1 mmol of cobalt nitrate (Co(NO3)2·6H2O), copper nitrate (Cu(NO3)2·3H2O), nickel nitrate (Ni(NO3)2·6H2O), zirconium nitrate (Zr(NO3)2·6H2O), and palladium nitrate (Pb(NO3)2), wherein the molar ratio of Co, Cu, Ni, Zr, and Pb is 1:1:1:1:1. Stir continuously for 3 h to completely dissolve the oxide. Then heat to 100 °C and keep stirring until the solution is completely evaporated to obtain CuCoNiZrPd / CeO2 powder.

[0055] Step 4: Preparation of (CuCoNiZrPdO) x ) 0.5 / CeO2 is a high-entropy metal oxide, specifically:

[0056] The CuCoNiZrPd / CeO2 powder obtained in step 3 was placed in a porcelain boat, its surface was covered with tin foil, and the tin foil was perforated. It was then calcined in air at a heating rate of 5 °C / min to 500 °C for 2 h to obtain a high-entropy metal oxide labeled (CuCoNiZrPdO). x ) 0.5 / CeO2 PS.

[0057] To facilitate the illustration of the performance of the catalyst obtained in Example 1 of this invention, a comparative sample was selected as a (CuCoNiZrPdO) catalyst with particulate CeO2 (CeO2 NP) as the support. x ) 0.5 The preparation method of / CeO2 high-entropy metal oxide is as follows:

[0058] Step 1, preparing CeO2 particles; specifically:

[0059] Step 1.1: Add 100 mL of deionized water and 2 g of Ce(NO3)2·6H2O to a beaker and stir with a magnetic stirrer for 30 min to dissolve.

[0060] Step 1.2: Slowly inject 2 ml of 15% ammonia solution into the solution obtained in step 1.1, stir at room temperature in air for 12 h, and then vacuum filter and wash with water to obtain a light yellow powder.

[0061] Step 2: Preparation of particulate CeO2 oxide; specifically:

[0062] After grinding, CeO2 powder was placed in a ceramic boat, the surface was covered with tin foil, and the tin foil was perforated. The mixture was then calcined in air at a heating rate of 1 °C / min to 500 °C for 3 h to obtain CeO2 particles.

[0063] With all other operating steps and parameters unchanged, a high-entropy metal oxide with CeO2 particles as the support for the control sample can be obtained, labeled as (CuCoNiZrPdO). x ) 0.5 / CeO2 NP.

[0064] Table 1 shows the elemental content ICP table obtained from Example 1 and the comparative sample. By comparing the actual loading mass percentage of metal on CeO2 porous sheets and CeO2 particles, it can be seen that CeO2 porous sheets are more conducive to metal loading, which is basically consistent with its theoretical mass ratio.

[0065] Table 1. Surface metal content of supported high-entropy metal oxides in Example 1

[0066]

[0067] Figure 1 The images shown are TEM (transmission electron microscopy) images obtained in Example 1 and the comparative sample, where a is CeO2 particles (CeO2 NP), b is CeO2 porous sheets (CeO2 PS), and c is (CuCoNiZrPdO) particles. x ) 0.5 / CeO2 NP (CeO2 particles loaded with high-entropy metal oxides), d is (CuCoNiZrPdO) x ) 0.5 / CeO2 PS (CeO2 porous sheet supported on high-entropy metal oxide), it can be seen that the (CuCoNiZrPdO) prepared in Example 1 is... x ) 0.5 Large in size and phase-separated from CeO2 particles; in contrast, CeO2 PS provides abundant adsorption and loading space for high-entropy metal oxides (CuCoNiZrPdO). x ) 0.5 It exhibits ultra-small nanoparticles and is uniformly loaded on the CeO2 PS surface.

[0068] Figure 2 and Figure 3 The figures show the BET diagram and pore size distribution obtained from Example 1 and the comparative sample. The figures show the specific surface area of ​​CeO2 PS (89.08 m²). 2 / g) is significantly higher than CeO2 NP (66.81 m) 2The CeO2 PS pore size (3.8 nm) is smaller than that of CeO2NP (9 nm), mainly due to the ultra-small grain size and abundant pore structure of CeO2 NP. Its high specific surface area and abundant lamellar pore structure are conducive to the adsorption of multi-metal ions, thereby promoting the uniform loading of high-entropy oxides on the surface. After loading with high-entropy oxides, the specific surface areas of both decreased to varying degrees, indicating that the high-entropy oxides were successfully loaded onto the support.

[0069] To investigate the effect of different metal loading amounts on the present invention, the following tests were conducted, using Example 1 as a comparison, and were specifically carried out according to the following steps:

[0070] In this embodiment, the total molar amount of metal salt added in step 3 of Example 1 was adjusted so that the molar ratio between the supported metal and the CeO2 support was 1:1, 1:2, 1:3, and 1:4, respectively, while all other operation steps and parameters remained unchanged. The resulting supported high-entropy metal oxides were, in order, (CuCoNiZrPdO) x ) / CeO2、(CuCoNiZrPdO x ) 0.5 / CeO2、(CuCoNiZrPdO x ) 0.33 / CeO2、(CuCoNiZrPdO x ) 0.25 / CeO2. The obtained supported high-entropy metal oxides were tested for their photothermal methanol-water reforming hydrogen production activity, such as... Figure 4 As shown in the figure, the results indicate that there is a clear parabolic relationship between the hydrogen production activity of the catalyst and the metal loading. Specifically, as the loading increases, the hydrogen production activity first gradually increases, and then decreases after reaching an optimal value (1:2).

[0071] To investigate the effect of photothermal conditions on the performance of the supported high-entropy metal oxide catalyst obtained in this invention, using Example 1 as the catalyst, the following tests were conducted under three conditions: photocatalysis, thermal catalysis, and photothermal synergistic catalysis. The specific steps are as follows:

[0072] The photocatalytic activity of methanol-water reforming for hydrogen production was tested under light-only conditions. Specifically, 10-20 mg of a supported high-entropy metal oxide catalyst was dispersed in a mixture of 40-60 ml methanol and deionized water. The mixture was sonicated for 10-30 min to ensure uniform dispersion of the solid powder in the solution. The dispersion was placed in a photothermal reactor, and nitrogen gas was introduced under stirring until the pressure on the reactor gauge reached 0.1-0.5 MPa. Vacuum was then applied for 2-6 min, and this process was repeated 2-5 times. After the reactor temperature stabilized at 30 °C, the xenon lamp was turned on with a light intensity of 0.2 W / cm². 2Photocatalytic methanol-water reforming was performed to produce hydrogen. After 2 hours of reaction, the xenon lamp was turned off, and the gas was then extracted and measured by gas chromatography.

[0073] The thermocatalytic activity of methanol-water reforming for hydrogen production was tested under heating conditions. Specifically, 10-20 mg of supported high-entropy metal oxide catalyst was dispersed in a mixture of methanol and deionized water (total volume 40-60 ml), and sonicated for 10-30 min to ensure uniform dispersion of the solid powder in the solution. The dispersion was placed in a photothermal reactor, and nitrogen gas was introduced under stirring until the pressure on the reactor gauge reached 0.1-0.5 MPa. Vacuum was then applied for 2-6 min, and this process was repeated 2-5 times. After the reactor temperature stabilized at 140 °C, thermocatalytic methanol-water reforming for hydrogen production was initiated. After 2 h of reaction, heating was turned off, and the reaction was allowed to cool to room temperature. The gas was then extracted and analyzed by gas chromatography.

[0074] The photothermal activity of methanol-water reforming for hydrogen production was tested under photothermal conditions. 10-20 mg of a supported high-entropy metal oxide catalyst was dispersed in a mixture of 40-60 ml methanol and deionized water. The mixture was sonicated for 10-30 min to ensure uniform dispersion of the solid powder. The dispersion was placed in a photothermal reactor, and nitrogen gas was introduced until the pressure on the reactor surface reached 0.1-0.5 MPa under stirring. Vacuum was then applied for 2-6 min, and this process was repeated 2-5 times. After the reactor temperature stabilized at 140 °C, the xenon lamp was turned on with a light intensity of 0.2 W / cm². 2 Photothermal catalytic methanol-water reforming was performed to produce hydrogen. After 2 hours of reaction, the xenon lamp and heating were turned off. After the reaction cooled to room temperature, the gas was extracted and measured by gas chromatography.

[0075] Experimental results show that ( Figure 5 Under the same conditions, room temperature photocatalysis (0.2 W / cm²) 2 The hydrogen production activity is very low (0.14 mol / g), while the photothermal coupled catalytic mode (140 ℃ + 0.2 W / cm²) has a much higher activity. 2 The hydrogen production activity of methanol-water reforming under photocatalysis (57.28 mol / g) was significantly higher than that under thermal catalysis (31.62 mol / g). This indicates that the reaction requires thermal energy for activation, while photoexcitation can effectively accelerate the molecular conversion process of hydrogen production, highlighting the key role of photothermal synergy in improving the catalytic performance of this supported high-entropy metal oxide.

[0076] Example 2

[0077] This invention provides a supported high-entropy metal oxide catalyst for photothermal methanol-water reforming to produce hydrogen, specifically implemented according to the following steps:

[0078] Step 1: Preparation of CeO2 gel; specifically:

[0079] Step 1.1: Add 100 mL of deionized water to a beaker, add 2 g of polyvinylpyrrolidone (PVP) as an ion complexing agent, and stir with a magnetic stirrer for 30 min to dissolve it.

[0080] Step 1.2: Add a total of 10 mmol of Ce(NO3)2·6H2O to the solution obtained in Step 1.1, and stir continuously for 60 min to completely dissolve it; then heat the solution to 70 °C and keep stirring until the solution is completely evaporated to obtain solid gel crystals;

[0081] Step 2: Preparation of porous CeO2 oxide sheets; specifically:

[0082] Step 2.1: Place the solid gel crystal block obtained in step 1.2 into a high-speed ball mill and ball mill at a speed of 800 rpm for 1.5 h to obtain uniform CeO2 gel powder.

[0083] Step 2.2: Place the CeO2 gel powder obtained in Step 1 in a ceramic boat, cover the surface with tin foil, and punch holes in the tin foil. Calcinate the powder in air at a heating rate of 3 °C / min to 550 °C for 5 h.

[0084] Step 3: Prepare CeO2-supported Cu, Fe, Ni, Cr, and Pd metal powders; specifically:

[0085] Add 100 ml of deionized water to a beaker, and add 2 mmol of CeO2 oxide obtained in step 2 as a carrier under stirring. Stir continuously for 30 min to completely disperse the oxide. Then add a total of 1 mmol of ferric nitrate (Fe(NO3)2·9H2O), copper nitrate (Cu(NO3)2·3H2O), nickel nitrate (Ni(NO3)2·6H2O), chromium nitrate (Cr(NO3)3·9H2O), and palladium nitrate (Pb(NO3)2), wherein the molar ratio of Fe, Cu, Ni, Cr, and Pb is 1:1:1:1:1. Stir continuously for 3 h to completely dissolve the oxide. Then heat to 60 °C and keep stirring until the solution is completely evaporated to obtain CuFeNiCrPd / CeO2 powder.

[0086] Step 4: Preparation of (CuFeNiCrPdO) x ) 0.5 / CeO2 is a high-entropy metal oxide, specifically:

[0087] CuFeNiCrPd / CeO2 powder was placed in a porcelain boat, its surface was covered with tin foil, and the tin foil was perforated. The mixture was then calcined in air at a heating rate of 5 °C / min to 550 °C for 4 h to obtain (CuFeNiCrPdO2) powder.x ) 0.5 / CeO2 is a high-entropy metal oxide.

[0088] Example 3

[0089] This invention provides a supported high-entropy metal oxide catalyst for photothermal methanol-water reforming to produce hydrogen, specifically implemented according to the following steps:

[0090] Step 1: Preparation of CeO2 gel; specifically:

[0091] Step 1.1: Add 100 mL of deionized water to a beaker, add 7 g of polyvinylpyrrolidone (PVP) as an ion complexing agent, and stir with a magnetic stirrer for 30 min to dissolve it.

[0092] Step 1.2: Add a total of 10 mmol of Ce(NO3)2·6H2O to the solution obtained in Step 1.1, and stir continuously for 60 min to completely dissolve it; heat the solution to 80 °C and keep stirring until the solution is completely evaporated to obtain solid gel crystals;

[0093] Step 2: Preparation of porous CeO2 oxide sheets; specifically:

[0094] Step 2.1: Place the solid gel crystal block obtained in step 1.2 into a high-speed ball mill and ball mill at a speed of 1000 rpm for 1 h to obtain uniform CeO2 gel powder.

[0095] Step 2.2: Place the CeO2 gel powder obtained in step 2.1 in a ceramic boat, cover the surface with tin foil, and punch holes in the tin foil. Calcinate the powder in air at a heating rate of 7 °C / min to 600 °C for 3 h.

[0096] Step 3: Prepare CeO2-supported Cu, Zn, Ni, Fe, and Pd metal powders; specifically:

[0097] Add 100 ml of deionized water to a beaker, and add 2 mmol of CeO2 oxide obtained in step 2 as a carrier under stirring. Stir continuously for 30 min to completely disperse the oxide. Then add a total of 1 mmol of zinc nitrate (Zn(NO3)2·6H2O), copper nitrate (Cu(NO3)2·3H2O), nickel nitrate (Ni(NO3)2·6H2O), iron nitrate (Fe(NO3)2·9H2O), and palladium nitrate (Pb(NO3)2), with the molar ratio of Zn, Cu, Ni, Fe, and Pb being 1:1:1:1:1. Stir continuously for 3 h to completely dissolve the oxide. Then heat to 80 °C and keep stirring until the solution is completely evaporated to obtain CuZnNiFePd / CeO2 powder.

[0098] Step 4: Preparation of (CuZnNiFePdO) x ) 0.5 / CeO2 is a high-entropy metal oxide, specifically:

[0099] CuZnNiFePd / CeO2 powder was placed in a porcelain boat, its surface was covered with tin foil, and the tin foil was perforated. The mixture was then calcined in air at a heating rate of 1 °C / min to 450 °C for 6 h to obtain (CuZnNiFePdO2) powder. x ) 0.5 / CeO2 is a high-entropy metal oxide.

[0100] Example 4

[0101] This invention provides a supported high-entropy metal oxide catalyst for photothermal methanol-water reforming to produce hydrogen, specifically implemented according to the following steps:

[0102] Step 1: Preparation of CeO2 gel; specifically:

[0103] Step 1.1: Add 100 mL of deionized water to a beaker, add 10 g of polyvinylpyrrolidone (PVP) as an ion complexing agent, and stir with a magnetic stirrer for 30 min to dissolve it.

[0104] Step 1.2: Add a total of 10 mmol of Ce(NO3)2·6H2O to the solution obtained in Step 1.1 and stir continuously for 60 min to completely dissolve it; heat the solution obtained in Step 1.2 to 60 °C and keep stirring until the solution is completely evaporated to obtain solid gel crystals;

[0105] Step 2: Preparation of porous CeO2 oxide sheets; specifically:

[0106] Step 2.1: Place the solid gel crystal block obtained in step 1.2 into a high-speed ball mill and ball mill at a speed of 1000 rpm for 1 h to obtain uniform CeO2 gel powder.

[0107] Step 2.2: Place the CeO2 gel powder obtained in step 2.1 in a ceramic boat, cover the surface with tin foil, and punch holes in the tin foil. Calcinate the powder in air at a heating rate of 5 °C / min to 700 °C for 2 h.

[0108] Step 3: Prepare CeO2-supported Mn, Co, Cd, Zr, and Pd metal powders; specifically:

[0109] Add 100 ml of deionized water to a beaker, and add 2 mmol of CeO2 oxide obtained in step 2 as a carrier under stirring. Stir continuously for 30 min to completely disperse the oxide. Then add a total of 1 mmol of manganese nitrate (Mn(NO3)2·4H2O), cobalt nitrate (Co(NO3)2·6H2O), cadmium nitrate (Cd(NO3)3·4H2O), zirconium nitrate (Zr(NO3)2·6H2O), and palladium nitrate (Pb(NO3)2), wherein the molar ratio of Fe, Cu, Ni, Cr, and Pb is 1:1:1:1:1. Stir continuously for 3 h to completely dissolve the oxide. Then heat to 100 °C and keep stirring until the solution is completely evaporated to obtain MnCoCdZrPd / CeO2 powder.

[0110] Step 4: Preparation of (MnCoCdZrPdO) x ) 0.5 / CeO2 is a high-entropy metal oxide, specifically:

[0111] MnCoCdZrPd / CeO2 powder was placed in a porcelain boat, covered with tin foil, and perforated. The mixture was then calcined in air at a heating rate of 7 °C / min to 550 °C for 4 h to obtain (MnCoCdZrPdO2) powder. x ) 0.5 / CeO2 is a high-entropy metal oxide.

[0112] To investigate the performance of the supported high-entropy metal oxide catalyst obtained in this invention, its photothermal methanol-water reforming hydrogen production activity was tested. Specifically, 10-20 mg of the supported high-entropy metal oxide catalyst was dispersed in a mixture of 40-60 ml methanol and deionized water, and sonicated for 10-30 min to ensure uniform dispersion of the solid powder in the solution. The dispersion was placed in a photothermal reactor, and nitrogen gas was introduced under stirring until the pressure on the reactor surface reached 0.1-0.5 MPa. Vacuum was then applied for 2-6 min, and this process was repeated 2-5 times. After the reactor temperature stabilized at 110-150 °C, the xenon lamp was turned on to initiate photothermal catalytic methanol-water reforming for hydrogen production. After 2-4 h of reaction, the xenon lamp and heating were turned off. Once the reaction cooled to room temperature, the gas was extracted and analyzed by gas chromatography.

[0113] The catalyst structure and performance test results are as follows:

[0114] Figure 6 The figures show the XRD patterns obtained in Examples 1, 2, and 3. The obtained supported high-entropy oxide (CuCoNiZrPdO) can be seen in the figures. x ) 0.5 / CeO2、(CuFeNiCrPdO x )0.5 / CeO2、(CuZnNiFePdO x ) 0.5 Both / CeO2 and CeO2 have the same single-phase crystal structure as CeO2, which is a cubic fluorite crystal form, and its unit cell standard card is CeO2-PDF#34-0394. By comparing the diffraction peak intensities, the sample (CuCoNiZrPdO) x ) 0.5 / CeO2、(CuZnNiFePdO x ) 0.5 The diffraction peak intensity of / CeO2 is slightly higher than that of CeO2, which indicates that loading high-entropy metal oxide further improves the overall crystallinity of the sample, forming a loaded high-entropy metal oxide with CeO2 as the main unit cell.

[0115] Figure 7 The elemental distribution mapping diagram obtained in Example 1 shows that Cu, Co, Ni, Zr, and Pd elements are uniformly distributed on the porous CeO2 sheet surface. Combined with characterization by XRD and TEM, it can be confirmed that a supported high-entropy metal oxide with a single-crystal structure and uniform elemental distribution was prepared.

[0116] Figure 8 The photothermal methanol-water reforming hydrogen production activity diagrams obtained in Examples 1, 2, 3, and 4 require only 140 °C heating and light irradiation (0.2 W / cm²). 2 Under the reaction conditions, the supported high-entropy oxides prepared by this invention exhibit good hydrogen production performance at low temperatures. At the same time, the hydrogen production activity of the catalyst can be effectively modulated by adjusting the active metal type of the high-entropy metal oxide.

[0117] The foregoing description illustrates and describes several preferred embodiments of the invention. However, as previously stated, it should be understood that the invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the invention should be within the protection scope of the appended claims.

Claims

1. A method for preparing a supported high-entropy metal oxide catalyst for photothermal methanol-water reforming to produce hydrogen, characterized in that, The specific steps are as follows: Step 1, prepare CeO2 gel; Step 2: Using the CeO2 gel obtained in Step 1 as raw material, first grind it to obtain CeO2 gel powder, and then calcine the CeO2 gel powder to obtain porous thin sheet CeO2 oxide. Step 3: Load various metal ions onto the porous CeO2 oxide sheets obtained in Step 2 to prepare multi-metal-loaded CeO2 powder; Step 4: Calcination treatment is performed on the multi-metal supported CeO2 powder obtained in Step 3. After grinding, a supported high-entropy metal oxide catalyst is obtained.

2. The method for preparing the supported high-entropy metal oxide catalyst for photothermal methanol-water reforming to produce hydrogen according to claim 1, characterized in that, In step 1, the preparation of CeO2 gel specifically involves: Step 1.1: Add polyvinylpyrrolidone to deionized water and allow it to dissolve completely; Step 1.2: Add cerium nitrate to the solution obtained in step 1.

1. After it is completely dissolved, heat it to 60-100 °C until the solution is completely evaporated to obtain solid gel crystals, namely CeO2 gel; wherein each 10 mmol of cerium nitrate corresponds to 2-10 g of polyvinylpyrrolidone.

3. The method for preparing the supported high-entropy metal oxide catalyst for photothermal methanol-water reforming to produce hydrogen according to claim 2, characterized in that, Step 2 is implemented in the following steps: Step 2.1: Place the solid gel crystal block obtained in step 1.2 into a ball mill and ball mill it to obtain a uniform porous carrier gel powder; Step 2.2: Place the porous carrier gel powder obtained in Step 2.1 in a ceramic boat, cover the surface with tin foil, and punch holes in the tin foil. Calcinate the powder in air at a heating rate of 1-7 ℃ / min to 400-800 ℃ for 2-8 h to obtain porous CeO2 oxide sheets.

4. The method for preparing the supported high-entropy metal oxide catalyst for photothermal methanol-water reforming to produce hydrogen according to claim 3, characterized in that, In step 3, specifically: The porous CeO2 oxide obtained in step 2 is added to deionized water and completely dispersed. Then, any 5-7 metal salts selected from manganese nitrate, cobalt nitrate, iron nitrate, copper nitrate, palladium nitrate, nickel nitrate, zirconium nitrate, cadmium nitrate, and zinc nitrate are added and completely dissolved. The solution is then heated to 60-100 °C until it is completely evaporated. After grinding, a multi-metal loaded powder is obtained. The total molar ratio of the porous CeO2 oxide to the selected metal salt is 1:0.1-1.

5. The method for preparing the supported high-entropy metal oxide catalyst for photothermal methanol-water reforming to produce hydrogen according to claim 2, characterized in that, Step 4 specifically involves placing the multi-metal supported CeO2 powder obtained in step 3 into a ceramic boat, covering the surface with tin foil, and punching holes in the tin foil. The powder is then calcined in air at a heating rate of 1-7 °C / min to 400-800 °C for 2-8 h. After grinding, a supported high-entropy metal oxide catalyst is obtained.

Images