Copper-ruthenium alloy photocatalyst, preparation method and application of copper-ruthenium alloy photocatalyst in preparation of synthesis gas by photocatalytic chemical-looping methane partial oxidation under mild condition

Abstract

The invention discloses a copper-ruthenium alloy photocatalyst, a preparation method and application of the copper-ruthenium alloy photocatalyst in preparation of synthesis gas by photocatalytic chemical-looping methane partial oxidation under mild conditions, and belongs to the technical field of methane catalytic conversion. The preparation method comprises the following steps: firstly, preparing a mixed metal oxide precursor by adopting a coprecipitation method, then preparing a mixed metal oxide through air calcination, finally, uniformly dispersing the mixed metal oxide by using a solvent, and evaporating the solvent to dryness to obtain catalyst powder with a uniform and flat surface. The photocatalyst is prepared by activating under a vacuum condition and then introducing methane for in-situ illumination, and can be used for partial oxidation reaction of photocatalytic chemical-looping methane under a mild condition and a relatively low pressure. According to the method, photocatalysis and a chemical looping strategy are organically combined, so that a competitive reaction of an oxidant and methane in a traditional direct oxidation system is avoided, generation of a by-product carbon dioxide is remarkably inhibited, the problem of high energy consumption caused by high temperature of thermocatalysis is avoided, and low-energy-consumption, high-selectivity and high-stability preparation of the synthesis gas is realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalytic conversion of methane, and particularly relates to a copper-ruthenium alloy photocatalyst, a preparation method thereof and application of the photocatalyst in preparation of synthesis gas through photocatalytic chemical looping partial oxidation of methane under mild conditions. BACKGROUND

[0002] With the gradual depletion of traditional petroleum resources and the increasing environmental problems, the development and utilization of new carbon sources are increasingly demanded in the chemical industry. Methane, as the main component of natural gas, coal-bed gas, shale gas and combustible ice, is abundant in reserves and low in price, and is considered as an important raw material source to replace petroleum. However, the methane molecule is a regular tetrahedron with a bond angle of 109.5°, has high symmetry and low polarizability, and is a typical nonpolar molecule. The dissociation energy of the C−H bond is as high as 439 kJ·mol −1 , and from the perspective of the molecular orbital of methane, the energy of the highest occupied orbital (HOMO) of the methane molecule is very low, and the energy of the lowest unoccupied orbital (LUMO) is very high, indicating that it requires extremely high energy to give or accept an electron, which makes it very difficult to be activated. In addition, the main storage sites of methane are located in remote areas, and its gaseous characteristics make the storage and transportation cost high, and there is a potential risk of easy leakage and greenhouse effect. Therefore, how to efficiently and safely convert methane into easily stored and higher value-added chemicals has become one of the important research directions in the field of energy and chemical industry.

[0003] The conversion of methane mainly includes two types: direct conversion and indirect conversion. Direct conversion of methane is to convert methane directly into high value-added chemicals such as liquid oxygen-containing compounds and hydrocarbons, which can theoretically improve energy efficiency and simplify process flow. Direct conversion of methane includes oxidation and non-oxidation two pathways. The non-oxidation pathway, i.e. the non-oxidative coupling reaction (NOCM) of methane, is an endothermic reaction, which usually requires extremely high temperature (>1000°C) to activate the inert C−H bond, which is easy to cause catalyst deactivation due to carbon deposition. The oxidation pathway is concerned by researchers due to its low energy consumption and good atom economy. However, it is still difficult for methane to couple into C 2+Methane is a hydrocarbon that readily produces a large amount of thermodynamically favorable byproduct CO2. Furthermore, partial oxidation of methane is difficult to selectively oxidize into oxygen-containing compounds and typically requires expensive oxidants (such as H2O2). Indirect methane conversion usually involves methane reforming to produce syngas (H2 and CO), which is then used to synthesize high-value-added chemicals such as ammonia, methanol, and olefins. This is currently the main route for the industrial utilization of methane. Typical reforming methods include steam reforming (SRM) and dry reforming (DRM), but these reactions are thermodynamically unfavorable at room temperature and require high temperature and pressure conditions, resulting in high energy consumption and cost, which is detrimental to sustainable development. In contrast, partial oxidation of methane (POM) is a thermodynamically spontaneous reaction with lower energy consumption and higher atom utilization efficiency. The theoretical H2 / CO molar ratio is 2:1, making it more suitable for subsequent methanol synthesis and Fischer-Tropsch synthesis processes. Therefore, it is considered one of the more ideal methane conversion routes.

[0004] Traditional partial oxidation (POM) processes typically rely on gaseous oxygen as an oxidant, with direct contact between fuel and oxygen, posing a significant explosion risk. Furthermore, the reaction is highly exothermic, making stable thermal management difficult. Secondly, precise control of oxygen concentration in the reaction system is challenging, easily leading to over-oxidation and the generation of large amounts of carbon dioxide and water, resulting in reduced syngas selectivity. To further improve the safety and selectivity of partial oxidation processes, researchers have proposed the chemically chained partial oxidation of methane (CLPOM) method. This method utilizes lattice oxygen in a recyclable carrier to achieve indirect oxygen transfer in different reaction environments, preventing direct contact between methane and air, thus effectively avoiding explosion risks. Highly selective syngas production is achieved through precise control of the lattice oxygen supply. Compared to traditional POM, the chemically chained partial oxidation of methane offers higher reaction safety, better oxygen utilization efficiency, and improved product control, providing a new technological approach for the clean and efficient conversion of methane. For example, Liang-Shih Fan et al. (Nat. Commun. 2019, 10, 5503) achieved near 100% CO selectivity by designing and synthesizing nanoscale iron oxide supports (Fe2O3@SBA-15) embedded in mesoporous silica (SBA-15), demonstrating that the co-generation of CO2 in the partial oxidation of methane in a chemical chain can be significantly suppressed. However, the reaction temperature of this cyclic redox system is between 750 and 935°C, which means that the reaction requires a huge amount of energy. Moreover, excessively high temperatures can easily cause sintering, agglomeration, or carbon deposition of the metal or oxide supports. Therefore, how to achieve efficient methane conversion under mild conditions has become a primary research goal for researchers.

[0005] Photocatalysis, as a promising solution, utilizes widely distributed and environmentally friendly solar energy to drive methane conversion under mild conditions, thereby avoiding catalyst sintering and carbon deposition and improving catalyst stability. Compared with traditional thermal reactions, the introduction of photon energy effectively lowers the activation barrier of methane and breaks the thermodynamic equilibrium, which is crucial for achieving efficient low-temperature methane conversion. Currently, photo-driven chemical chaining strategies have been applied to methane conversion reactions. For example, Khodakov et al. (Nat. Energy 2020, 5, 511-519) achieved highly selective and almost quantitative ethane production by using highly dispersed silver ions in a silver-phosphotungstic acid-titanium dioxide nanocomposite material (Ag-HPW / TiO2) to react stoichiometrically with methane. + ↔Ag 0 A cyclic redox system separates the CH4 oxidation and O2 reduction steps, effectively suppressing the over-oxidation of methane. This study confirms the feasibility of photo-driven chemical chaining processes for methane activation at low temperatures and provides a new approach to reducing energy consumption and avoiding catalyst deactivation in traditional thermocatalytic chemical chaining reactions. Introducing photochemistry into the chemical chaining methane partial oxidation (CLPOM) system holds promise for achieving efficient activation and selective conversion of methane under mild conditions. This technology not only fills the gap in existing research on photocatalytic chemical chaining methane partial oxidation but also provides a new pathway for the clean and efficient utilization of methane and carbon neutrality, possessing significant scientific value and application prospects. Summary of the Invention

[0006] The purpose of this invention is to provide a copper-ruthenium alloy photocatalyst, its preparation method, and its application in the photocatalytic partial oxidation of methane to syngas under mild conditions. The copper-ruthenium alloy photocatalyst prepared by this invention enhances light absorption and utilization. Furthermore, by controlling the copper-ruthenium ratio and metal loading, it exhibits a significantly enhanced catalytic effect on the photocatalytic partial oxidation of methane to syngas. To achieve the above objective, this invention first prepares a mixed metal oxide precursor using a co-precipitation method, then obtains the mixed metal oxide through air calcination, and finally disperses the mixed metal oxide uniformly with a solvent. After evaporating the solvent, a catalyst powder with a uniform and smooth surface is obtained. This powder is then activated under vacuum conditions and subsequently irradiated with in-situ methane light to obtain a highly active and stable copper-ruthenium alloy photocatalyst. After spin-coating onto a glass fiber membrane and vacuum activation, it can be used for the photocatalytic partial oxidation of methane under mild conditions and low pressure. This invention organically combines photocatalysis with a chemical chaining strategy, which avoids the competitive reaction between the oxidant and methane in traditional direct oxidation systems, significantly suppressing the generation of carbon dioxide as a byproduct, and also avoids the high energy consumption problem of thermal catalysis at high temperatures. Ultimately, it achieves low-energy, high-selectivity, and high-stability preparation of syngas.

[0007] The preparation method of the copper-ruthenium alloy photocatalyst of the present invention comprises the following steps: (1) First, magnesium precursor, aluminum precursor, copper precursor, and ruthenium precursor were added to deionized water and stirred in an oil bath at 353~373 K. Then, a precipitant was added, and the pH was adjusted to 8~10. The mixture was stirred for 12~24 h to obtain a solution. The magnesium precursor was either magnesium chloride or magnesium nitrate, with a dosage range of 0~2.288 g. The aluminum precursor was either aluminum nitrate or aluminum chloride, with a dosage range of 0~1.5 g, and the dosages of magnesium and aluminum precursors were not both 0. The copper precursor was either copper nitrate or copper chloride, with a dosage range of 0.2392~0.9568 g. The ruthenium precursor was either ruthenium chloride, ruthenium nitrate, ruthenium acetylacetonate, or ruthenium dodecylcarbonyl, with a dosage range of 1.96~39.2 g. mg; The precipitant is one of sodium carbonate, sodium hydroxide, or ammonia water, and the ratio of the amount of precipitant added to the amount of all metal substances in the precursor is 1:1~2; (2) After the mixture solution obtained in step (1) is cooled to room temperature, the product is centrifuged and washed with deionized water 4 to 6 times until the pH value of the filtrate is 7; after drying at 353 to 393 K for 12 to 24 h, a mixed metal oxide precursor is obtained; then the mixed metal oxide precursor is heated to 573 to 1073 K in air at a rate of 1 to 10 K / min and held for 2 to 4 h to obtain a mixed metal oxide; (3) Weigh the mixed metal oxide obtained in step (2) and disperse it uniformly in a solvent (anhydrous ethanol, deionized water, acetone, etc.) at a concentration of 1~10 mg / mL. Then, keep it at 323~373 K for 0.5~1 h to completely evaporate the solvent and obtain a powder with a uniform and smooth surface. Then, under vacuum conditions (pressure less than 2 Pa), heat it to 473~533 K at a rate of 1~10 K / min to activate it for 1~2 h to remove impurities and residual solvent adsorbed on the surface. After cooling to room temperature, introduce methane gas (purity 99.999%, pressure 20~1000 mbar) and finally irradiate it under a light source with a wavelength range of 300~2500 nm for 10~30 min to obtain a copper ruthenium alloy catalyst supported on a mixed oxide of magnesium oxide and aluminum oxide, or supported on magnesium oxide, or supported on aluminum oxide, which is the copper ruthenium alloy catalyst for photocatalytic partial oxidation of methane in a chemical chain.

[0008] The copper-ruthenium alloy photocatalyst described in this invention is prepared by the above-described preparation method.

[0009] This invention also relates to the application of the above-mentioned copper-ruthenium alloy catalyst in the photocatalytic chemical chain partial oxidation of methane to syngas under mild conditions, the specific steps of which are as follows: (1) Disperse the copper-ruthenium alloy catalyst in a solvent (anhydrous ethanol, deionized water or acetone) at a concentration of 1~10 mg / mL; then spin-coat the obtained dispersion onto the surface of the glass fiber membrane and dry it at 323~373 K for 0.5~1 h to remove the solvent and obtain a catalyst membrane with a uniform and smooth surface. (2) Place the catalyst film obtained in step (1) at the bottom of the quartz reactor and heat it to 473-533 K at a rate of 1-10 K / min under vacuum conditions (pressure less than 2 Pa) for 1-2 h to remove impurities and residual solvents adsorbed on the catalyst surface. (3) After the catalyst activated in step (2) is cooled to room temperature, high-purity methane gas (purity 99.999%, pressure 20~1000 mbar) is introduced into the quartz reactor and reacted for 0.5~120 min under the irradiation of a light source with a wavelength range of 300~2500 nm, thereby realizing the partial oxidation of methane in the photocatalytic chemical chain.

[0010] Photocatalytic partial oxidation of methane involves the reaction of lattice oxygen in a copper-ruthenium alloy catalyst with methane to selectively produce syngas (carbon monoxide and hydrogen). The main reaction is: CH4 + O2. lattice →CO + 2H₂; Side reaction: CH₄ + 2O lattice →CO2+2H2,CH4→C+2H2; During the catalytic reaction, the lattice oxygen of the catalyst is continuously consumed. After each reaction, the catalyst needs to be exposed to air for 2-10 minutes to replenish the lattice oxygen. The catalytic effect of the replenished catalyst remains unchanged, and the cycle performance is good. After the reaction is completed, the quartz reactor is cooled to room temperature, and 1 mL of the gas after the reaction is extracted from the quartz reactor using a gas-tight needle. The peak areas of hydrogen, methane, carbon monoxide, and carbon dioxide in the quartz reactor after the reaction are determined by gas chromatography (GC). The results are then analyzed using a standard curve (…). Figure 3 (a) Calculate the amount of hydrogen in the product; use a standard curve ( Figure 3 (bd) Calculate the conversion rate of methane, the formation rate and yield of carbon monoxide and the byproduct carbon dioxide, and the formation rate of the byproduct coke. The calculation formulas are as follows:

[0011] The advantages of this invention compared to the prior art are: (1) The photocatalyst of the present invention has a simple synthesis step, short time consumption, and is easy to mass-produce; the solvent used in the reaction is mostly deionized water, which is green and environmentally friendly; the requirements for reaction conditions and reaction equipment are not high, and it has good reproducibility and industrial scale-up potential. (2) This invention organically combines photocatalysis with chemical chaining strategy, avoiding the competitive reaction between oxidant and methane in traditional direct oxidation system, significantly inhibiting the generation of by-product carbon dioxide, and improving the selectivity of methane to target products such as carbon monoxide and hydrogen. The selectivity of carbon monoxide in this reaction is as high as 99%, and the molar ratio of hydrogen to carbon monoxide is 2:1, which is more suitable for subsequent methanol synthesis and Fischer-Tropsch synthesis. (3) This invention is the first to realize the photocatalytic partial oxidation of chemical chain methane to prepare syngas under mild conditions, which effectively avoids the disadvantage of high temperature (≥973 K) of traditional thermocatalytic chemical chain methane partial oxidation, greatly reduces energy consumption, and suppresses side reactions caused by high temperature, greatly improves the stability of the catalyst. The photocatalyst showed no significant decay within 20 cycles of testing, and the selectivity remained almost unchanged. Attached Figure Description

[0012] Figure 1 (a) shows the synthesized magnesium oxide (MgO), magnesium oxide-aluminum oxide mixed oxide (MgO-Al2O3, abbreviated as MA), and magnesium oxide-aluminum oxide mixed oxide (Cu) loaded with pure copper nanoparticles. 20 / MA), a mixed oxide of magnesium oxide and aluminum oxide supported on copper ruthenium alloy (Cu 19.8 Ru 0.2 The XRD pattern of the synthesized MgO (MgO / MA) matches the standard card, indicating that MgO is a pure phase. The synthesized MA is shifted at a higher angle compared to MgO, suggesting that MA is mostly in the form of magnesium oxide, with some Al incorporated into MgO. Furthermore, in Cu... 20 The detection of peaks matching the Cu standard card in / MA indicates that Cu exists in the form of nanoparticles. The absence of Ru peaks indicates that Ru is uniformly dispersed in Cu. Figure 1 (b) CuRu alloys with different proportions were synthesized and supported on a mixture of magnesium oxide and aluminum oxide (Cu). 20 Cu 19.95 Ru 0.05 Cu 19.9 Ru 0.1 Cu 19.8 Ru 0.2 Cu 19.5 Ru 0.5 Cu 19 The XRD pattern of Ru1) did not show any Ru peaks, which indicates that the synthesis method described above can disperse Ru in Cu evenly and that Ru has a small size, corresponding to Examples 1, 2, 4 to 8; Figure 2 (a) A mixed oxide of magnesium oxide and aluminum oxide (Cu) containing copper-ruthenium alloy synthesized in this invention. 19.8 Ru 0.2Transmission electron microscopy (TEM) images ( / MA) show that Cu nanoparticles are uniformly dispersed on a magnesium oxide and aluminum oxide mixed oxide. Figure 2 (b) is Cu 19.8 Ru 0.2 The particle size distribution of / MA shows that the sample particle size is mainly between 6 and 20 nm, with 13 nm accounting for a large proportion, indicating that the particle size of Cu nanoparticles is about 13 nm. Figure 2 (c) is Cu 19.8 Ru 0.2 / MA high-resolution transmission electron microscope (HR-TEM) image, scale bar 5 nm, showing that MgO mainly exposes {200} crystal planes with a {200} lattice spacing of 2.08 Å, and Cu mainly exposes {111} crystal planes with a {111} lattice spacing of 2.06 Å, corresponding to Example 1; Figure 3 (a) is the standard curve for determining different amounts of hydrogen using gas chromatography (GC); The curve equation is y = 1.64x, where y represents the peak area of ​​hydrogen gas as measured by gas chromatography (GC), and x represents the amount of hydrogen gas introduced into the 88 mL sealed quartz reactor, in μmol. First, five different amounts of hydrogen gas are introduced into the 88 mL sealed quartz reactor. Then, 1 mL of gas is extracted from the quartz reactor sequentially using a gas-tight needle and injected into the gas chromatograph to obtain the corresponding hydrogen peak area. This yields a standard curve of hydrogen peak area versus amount of methane. Figure 3 (b) Standard curves for determining different amounts of methane using gas chromatography (GC); The curve equation is y = 2.41x, where y represents the peak area of ​​methane as measured by gas chromatography (GC), and x represents the amount of methane introduced into the 88 mL sealed quartz reactor, in μmol. First, five different amounts of methane are introduced into the 88 mL sealed quartz reactor. Then, 1 mL of gas is extracted from the quartz reactor sequentially using a gas-tight needle and injected into the gas chromatograph to obtain the corresponding methane peak area. This yields a standard curve of methane peak area versus amount of methane. This standard curve is mainly used to calculate the amount of methane before and after the reaction, thereby obtaining the amount of methane consumed to verify the carbon balance in the reaction. Figure 3 (c) Standard curves for determining different amounts of carbon monoxide using gas chromatography (GC); The curve equation is y = 1.86x, where y represents the peak area of ​​carbon monoxide as measured by gas chromatography (GC), and x represents the amount of carbon monoxide introduced into an 88 mL sealed quartz reactor, in μmol. First, five different amounts of carbon monoxide are introduced into the 88 mL sealed quartz reactor. Then, 1 mL of gas is extracted from the quartz reactor sequentially using a gas-tight needle and injected into a gas chromatograph to obtain the corresponding carbon monoxide peak area. This yields a standard curve of carbon monoxide peak area versus amount of carbon monoxide. Figure 3 (d) is the standard curve for determining different amounts of carbon dioxide using gas chromatography (GC); The curve equation is y = 2.20x, where y represents the peak area of ​​carbon dioxide as measured by gas chromatography (GC), and x represents the amount of carbon dioxide introduced into the 88 mL sealed quartz reactor, in μmol. First, five different amounts of carbon dioxide are introduced into the 88 mL sealed quartz reactor. Then, 1 mL of gas is extracted from the quartz reactor sequentially using a gas-tight needle and injected into the gas chromatograph to obtain the corresponding carbon dioxide peak area. This yields a standard curve of carbon dioxide peak area versus amount of carbon dioxide. Figure 4 : To support CuRu alloys with different proportions on a mixture of magnesium oxide and aluminum oxide (Cu 20 Cu 19.95 Ru 0.05 Cu 19.9 Ru 0.1 Cu 19.8 Ru 0.2 Cu 19.5 Ru 0.5 Cu 19 The photocatalytic performance of CuRu1 is shown in the graph; the vertical axis represents the product formation rate, and the horizontal axis represents the proportion of CuRu alloy. Different colored bars represent different products (black: carbon monoxide, white: carbon dioxide, gray: carbon deposits). This graph illustrates the photocatalytic performance of CuRu1. 19.8 Ru 0.2 It has the highest CO selectivity, with undoped or low Ru doping ratio (Cu). 20 Cu 19.95 Ru 0.05 Cu 19.9 Ru 0.1 The product contains a large amount of carbon dioxide, and an excessively high Ru doping ratio (Cu) 19.5 Ru 0.5 Cu 19 Ru1) will produce carbon deposits, corresponding to Examples 1, 5-8; Figure 5The graph shows the photocatalytic performance of magnesium oxide and aluminum oxide mixed oxides with different CuRu loadings. The horizontal axis represents the ratio of CuRu to MA support. The bars on the left vertical axis represent the product yields for different CuRu loadings, with different colored bars representing different products (black: carbon monoxide, white: carbon dioxide). The dotted line graph on the right vertical axis represents the methane conversion rate under different CuRu loadings, in mmol•g. CuRu -1 •h -1 The figure reflects the utilization efficiency of unit mass of active metal component (CuRu) for the partial oxidation reaction of chemically chained methane. The figure shows that as the amount of CuRu loaded increases, the methane conversion rate first increases and then decreases, showing a volcano curve trend, and reaches the highest when n(CuRu):n(MA)=1:4. This indicates that the catalyst at this ratio has the highest CuRu metal utilization efficiency, corresponding to Examples 1, 9-12. Figure 6 : This graph shows the photocatalytic performance of different catalysts; the horizontal axis represents different catalysts, from left to right: magnesium oxide-alumina mixed oxide (MA), ruthenium-supported magnesium oxide-alumina mixed oxide (Ru). 0.2 / MA), a magnesium oxide-alumina mixed oxide loaded with copper nanoparticles (Cu 20 / MA), a mixed oxide of magnesium oxide and aluminum oxide supported on copper ruthenium alloy (Cu 19.8 Ru 0.2 / MA), the vertical axis represents the product formation rate, and different colored bars represent different products (black: carbon monoxide, white: carbon dioxide); this graph illustrates Cu 19.8 Ru 0.2 / MA exhibits the highest product formation rate and CO selectivity, indicating that the formation of copper-ruthenium alloys can significantly enhance the performance of photocatalytic chemical chain methane partial oxidation reaction, corresponding to Examples 1-4; Figure 7 : A mixed oxide of magnesium oxide and aluminum oxide supported on copper-ruthenium alloy (Cu 19.8 Ru 0.2 / MA) Thermocatalytic performance at different temperatures; the horizontal axis represents different reaction temperatures, the vertical axis represents the product formation rate, and different colored bars represent different products (black: carbon monoxide, white: carbon dioxide); the graph shows that although the product formation rate increases with increasing temperature, it is still much lower than the product formation rate under photocatalytic conditions. This indicates that the reaction is mainly initiated by light rather than by heat generated by light, and further illustrates the significant promoting effect of light on the partial oxidation reaction of chemical chain methane, corresponding to Example 13; Figure 8 : A mixed oxide of magnesium oxide and aluminum oxide supported on copper-ruthenium alloy (Cu19.8 Ru 0.2 / MA) Cyclic stability plot with the catalyst not exposed to air after each reaction; the horizontal axis represents the number of cycles, and the vertical axis represents the conversion rate of methane; the plot shows that the conversion rate of methane continuously decreases within 10 cycles without replenishment of lattice oxygen, which indicates the necessity of exposing the catalyst to air after each reaction to replenish lattice oxygen, and also proves that the reaction is mediated by lattice oxygen, corresponding to Example 14. Figure 9 : A mixed oxide of magnesium oxide and aluminum oxide supported on copper-ruthenium alloy (Cu 19.8 Ru 0.2 / MA) Cyclic stability graph of catalyst exposed to air after each reaction; the horizontal axis represents the number of cycles, and the bars on the left corresponding to the vertical axis represent the methane conversion rate per cycle, with different colored bars representing different products (black: carbon monoxide, white: carbon dioxide); the dotted line graph on the right corresponding to the vertical axis represents the selectivity per cycle (molar amount of hydrogen / molar amount of carbon monoxide), with one bar and one dot per cycle; this graph illustrates Cu 19.8 Ru 0.2 The reactivity of / MA did not show significant decay after 20 cycles, indicating that Cu 19.8 Ru 0.2 The MA catalyst has good cycle stability and can be reused multiple times, as shown in Example 15. Detailed Implementation

[0013] The following specific embodiments provide a further detailed description of the present invention. The specific operational processes in these embodiments will enable those skilled in the art to more fully understand the present invention. The embodiments described below are only some embodiments of the present invention, not all of them. Therefore, the scope of protection of the present invention is not limited to the following embodiments.

[0014] Example 1 Preparation method of magnesium oxide and aluminum oxide mixed oxide catalyst supported on copper-ruthenium alloy and its application in photocatalytic chemical chain methane partial oxidation to syngas: (1) Weigh 1.830 g magnesium chloride hexahydrate (MgCl2•6H2O), 1.125 g aluminum nitrate (Al(NO3)3•9H2O), 0.7176 g copper nitrate (Cu(NO3)2•3H2O) and 7.84 mg ruthenium chloride (RuCl3•3H2O) and add them to 15 mL of deionized water. Stir the solution in an oil bath at 373 K. Then add 1.2 M sodium carbonate solution to the solution to adjust the pH to 8 and stir for 24 h. After the solution cools to room temperature, centrifuge the product and wash it 4 times with deionized water until the pH of the filtrate is 7. Dry the product in an oven at 373 K for 12 h to obtain a mixed metal oxide precursor. Heat the mixed metal oxide precursor to 873 K in air at a rate of 5 K / min and hold for 2 h to obtain a mixed metal oxide. (2) Weigh 100 mg of the obtained mixed metal oxide, place it at the bottom of a quartz reactor and disperse it evenly in acetone. Keep it at 353 K for 0.5 h to completely evaporate the solvent and obtain a powder with a uniform and smooth surface. Under vacuum conditions (pressure less than 2 Pa), heat it to 513 K at 5 K / min and activate it for 1 h to remove impurities and residual solvent adsorbed on the catalyst surface. After cooling to room temperature, introduce 100 mbar methane gas (purity 99.999%) and finally irradiate it with a 300 W xenon lamp (wavelength range 300~2500 nm, PLS-SXE300D) for 20 min to obtain 100 mg of magnesium oxide and aluminum oxide mixed oxide catalyst supported on copper ruthenium alloy, which is named Cu 19.8 Ru 0.2 / MA (abbreviated as Cu) 19.8 Ru 0.2 ), where n(Cu 19.8 Ru 0.2 ):n(MA)=1:4; (3) Weigh 20 mg of the prepared catalyst into a 25 mL beaker, add 10 mL of deionized water and sonicate to disperse it evenly; use spin coating to evenly coat the obtained dispersion onto the surface of a glass fiber membrane (Shanghai Xingya Purification Materials Factory), dry at 353 K for 0.5 h to obtain a catalyst membrane with a uniform and smooth surface; place the catalyst membrane at the bottom of a quartz reactor, heat it to 513 K at 5 K / min under vacuum conditions (pressure less than 2 Pa), and activate it for 1 h to remove impurities and residual solvents adsorbed on the catalyst surface; after cooling to room temperature, introduce 28.5 mbar of high-purity methane gas (purity 99.999%) into the quartz reactor, and irradiate it with a 300 W xenon lamp (wavelength range 300~2500 nm, PLS-SXE300D) to carry out photocatalytic chemical chain partial oxidation of methane to prepare syngas (carbon monoxide and hydrogen), with an irradiation time of 5 minutes. min; after the reaction is complete, the components of the product are quantitatively analyzed by gas chromatography (GC-2014C). 1 mL of gas is extracted from the quartz reactor using a gas-tight needle and injected into the gas chromatograph to obtain the peak area of ​​hydrogen. The peak area is then analyzed using a standard curve (…). Figure 3 (a) The amount of hydrogen produced can be calculated. Then, 1 mL of gas is extracted from the quartz reactor using a gas-tight needle and injected into a gas chromatograph to obtain the peak areas of methane, carbon monoxide, and carbon dioxide. The peak areas are then analyzed using a standard curve. Figure 3 (bd)) can calculate the amount of methane consumed and the amount of carbon monoxide and carbon dioxide produced. Then, the conversion rate of methane, the generation rate and yield of carbon monoxide and carbon dioxide, and the formation rate of coke can be calculated using the above formula. (4) The conversion rate of methane was calculated to be 24.54 mmol·g. -1 ·h -1 (66.60 mmol·g) CuRu -1 ·h -1 The carbon monoxide formation rate was 24.44 mmol·g. -1 ·h -1 (The yield of carbon monoxide was 40.9%), and the rate of carbon dioxide production was 0.1 mmol·g. -1 ·h -1 (The yield of carbon dioxide is 0.17%).

[0015] Example 2 Preparation method of magnesium oxide and aluminum oxide mixed oxide catalyst loaded with copper nanoparticles and its application in photocatalytic chemical chain methane partial oxidation to syngas: (1) Weigh 1.830 g magnesium chloride hexahydrate (MgCl2•6H2O), 1.125 g aluminum nitrate (Al(NO3)3•9H2O) and 0.7248 g copper nitrate (Cu(NO3)2•3H2O) and add them to 15 mL of deionized water. Stir the solution in an oil bath at 373 K. Then add 1.2 M sodium carbonate solution to the solution to adjust the pH to 8 and stir for 24 h. After the solution cools to room temperature, centrifuge the product and wash it 4 times with deionized water until the pH of the filtrate is 7. Dry the product in an oven at 373 K for 12 h to obtain a mixed metal oxide precursor. Heat the mixed metal oxide precursor to 873 K in an air atmosphere at 5 K / min and hold for 2 h to obtain a mixed metal oxide. (2) Weigh 100 mg of the obtained mixed metal oxide, place it at the bottom of the quartz reactor and disperse it evenly in acetone. Keep it at 353 K for 0.5 h to completely evaporate the solvent and obtain a powder with a uniform and smooth surface. Under vacuum conditions (pressure less than 2 Pa), heat it to 513 K at 5 K / min and activate it for 1 h to remove impurities and residual solvent adsorbed on the catalyst surface. After cooling to room temperature, introduce 100 mbar methane gas (purity 99.999%) and finally irradiate it with a 300 W xenon lamp (wavelength range 300~2500 nm, PLS-SXE300D) for 20 min to obtain 100 mg of magnesium oxide and aluminum oxide mixed oxide catalyst loaded with copper nanoparticles, which is named Cu 20 / MA (abbreviated as Cu) 20 ); (3) Same as step (3) in Example 1; (4) The conversion rate of methane was calculated to be 8.85 mmol·g. -1 ·h -1 The carbon monoxide formation rate was 4.48 mmol·g. -1 ·h -1 The carbon dioxide production rate was 4.37 mmol·g. -1 ·h -1 .

[0016] Example 3 Preparation method of ruthenium-supported magnesium oxide and aluminum oxide mixed oxide catalyst and its application in photocatalytic chemical chain methane partial oxidation to syngas: (1) Weigh 1.830 g magnesium chloride hexahydrate (MgCl2•6H2O), 1.125 g aluminum nitrate (Al(NO3)3•9H2O), and 7.84 mg ruthenium chloride (RuCl3•3H2O) and add them to 15 mL of deionized water. Stir the solution in an oil bath at 373 K. Then, add 1.2 M sodium carbonate solution dropwise to adjust the pH to 8 and stir for 24 h. After the solution cools to room temperature, centrifuge the product and wash it four times with deionized water until the pH of the filtrate is 7. Dry the product in an oven at 373 K for 12 h to obtain a mixed metal oxide precursor. Heat the mixed metal oxide precursor to 873 K in air at 5 K / min and hold for 2 h to obtain a mixed metal oxide. Obtain the ruthenium-supported magnesium oxide and aluminum oxide mixed oxide catalyst, which is named RuCl3•3H2O. 0.2 / MA; (2) Same as step (3) in Example 1; (3) The conversion rate of methane was calculated to be 4.01 mmol·g. -1 ·h -1 The rate of carbon monoxide formation is 0.5 mmol·g. -1 ·h -1 The carbon dioxide production rate was 3.51 mmol·g. -1 ·h -1 .

[0017] Example 4 Preparation method of magnesium oxide and aluminum oxide mixed oxide catalyst and its application in photocatalytic chemical chain methane partial oxidation to syngas: (1) Weigh 1.830 g magnesium chloride hexahydrate (MgCl2•6H2O) and 1.125 g aluminum nitrate (Al(NO3)3•9H2O) and add them to 15 mL of deionized water. Stir the mixture in an oil bath at 373 K. Then, add 1.2 M sodium carbonate solution dropwise to the solution to adjust the pH to 8 and stir for 24 h. After the solution cools to room temperature, centrifuge the product and wash it 4 times with deionized water until the pH of the filtrate is 7. Dry the product in an oven at 373 K for 12 h to obtain a mixed metal oxide precursor. Heat the mixed metal oxide precursor to 873 K in an air atmosphere at 5 K / min and hold for 2 h to obtain a mixed metal oxide. A mixed oxide catalyst of magnesium oxide and aluminum oxide is obtained and named MgO-Al2O3 (abbreviated as MA). (2) Same as step (3) in Example 1; (3) The conversion rate of methane was calculated to be 0.24 mmol·g. -1 ·h -1 The rate of carbon monoxide formation is 0.13 mmol·g.-1 ·h -1 The carbon dioxide production rate was 0.11 mmol·g. -1 ·h -1 .

[0018] Example 5 Preparation method of magnesium oxide and aluminum oxide mixed oxide catalyst supported on copper-ruthenium alloy and its application in photocatalytic chemical chain methane partial oxidation to syngas: (1) Weigh 1.830 g magnesium chloride hexahydrate (MgCl2•6H2O), 1.125 g aluminum nitrate (Al(NO3)3•9H2O), 0.7230 g copper nitrate (Cu(NO3)2•3H2O) and 1.96 mg ruthenium chloride (RuCl3•3H2O) and add them to 15 mL of deionized water. Stir the solution in an oil bath at 373 K. Then add 1.2 M sodium carbonate solution to the solution to adjust the pH to 8 and stir for 24 h. After the solution cools to room temperature, centrifuge the product and wash it 4 times with deionized water until the pH of the filtrate is 7. Dry the product in an oven at 373 K for 12 h to obtain a mixed metal oxide precursor. Heat the mixed metal oxide precursor to 873 K in air at 5 K / min and hold for 2 h to obtain a mixed metal oxide. (2) Weigh 100 mg of the obtained mixed metal oxide, place it at the bottom of a quartz reactor and disperse it evenly in acetone. Keep it at 353 K for 0.5 h to completely evaporate the solvent and obtain a powder with a uniform and smooth surface. Under vacuum conditions (pressure less than 2 Pa), heat it to 513 K at 5 K / min and activate it for 1 h to remove impurities and residual solvent adsorbed on the catalyst surface. After cooling to room temperature, introduce 100 mbar methane gas (purity 99.999%) and finally irradiate it with a 300 W xenon lamp (wavelength range 300~2500 nm, PLS-SXE300D) for 20 min to obtain 100 mg of magnesium oxide and aluminum oxide mixed oxide catalyst supported on copper ruthenium alloy, which is named Cu 19.95 Ru 0.05 / MA (abbreviated as Cu) 19.95 Ru 0.05 ); (3) Same as step (3) in Example 1; (4) The conversion rate of methane was calculated to be 11.04 mmol·g. -1 ·h -1 The carbon monoxide formation rate was 6.53 mmol·g. -1 ·h -1 The carbon dioxide production rate was 4.51 mmol·g. -1 ·h-1 .

[0019] Example 6 Preparation method of magnesium oxide and aluminum oxide mixed oxide catalyst supported on copper-ruthenium alloy and its application in photocatalytic chemical chain methane partial oxidation to syngas: (1) Weigh 1.830 g magnesium chloride hexahydrate (MgCl2•6H2O), 1.125 g aluminum nitrate (Al(NO3)3•9H2O), 0.7212 g copper nitrate (Cu(NO3)2•3H2O) and 3.92 mg ruthenium chloride (RuCl3•3H2O) and add them to 15 mL of deionized water. Stir the solution in an oil bath at 373 K. Then add 1.2 M sodium carbonate solution to the solution to adjust the pH to 8 and stir for 24 h. After the solution cools to room temperature, centrifuge the product and wash it 4 times with deionized water until the pH of the filtrate is 7. Dry the product in an oven at 373 K for 12 h to obtain a mixed metal oxide precursor. Heat the mixed metal oxide precursor to 873 K in air at 5 K / min and hold for 2 h to obtain a mixed metal oxide. (2) Weigh 100 mg of the obtained mixed metal oxide, place it at the bottom of a quartz reactor and disperse it evenly in acetone. Keep it at 353 K for 0.5 h to completely evaporate the solvent and obtain a powder with a uniform and smooth surface. Under vacuum conditions (pressure less than 2 Pa), heat it to 513 K at 5 K / min and activate it for 1 h to remove impurities and residual solvent adsorbed on the catalyst surface. After cooling to room temperature, introduce 100 mbar methane gas (purity 99.999%) and finally irradiate it with a 300 W xenon lamp (wavelength range 300~2500 nm, PLS-SXE300D) for 20 min to obtain 100 mg of magnesium oxide and aluminum oxide mixed oxide catalyst supported on copper ruthenium alloy, which is named Cu 19.9 Ru 0.1 / MA (abbreviated as Cu) 19.95 Ru 0.1 ); (3) Same as step (3) in Example 1; (4) The conversion rate of methane was calculated to be 15.33 mmol·g. -1 ·h -1 The carbon monoxide formation rate was 11.04 mmol·g. -1 ·h -1 The carbon dioxide production rate was 4.29 mmol·g. -1 ·h -1 .

[0020] Example 7 Preparation method of magnesium oxide and aluminum oxide mixed oxide catalyst supported on copper-ruthenium alloy and its application in photocatalytic chemical chain methane partial oxidation to syngas: (1) Weigh 1.830 g magnesium chloride hexahydrate (MgCl2•6H2O), 1.125 g aluminum nitrate (Al(NO3)3•9H2O), 0.7067 g copper nitrate (Cu(NO3)2•3H2O) and 19.6 mg ruthenium chloride (RuCl3•3H2O) and add them to 15 mL of deionized water. Stir the solution in an oil bath at 373 K. Then add 1.2 M sodium carbonate solution to the solution to adjust the pH to 8 and stir for 24 h. After the solution cools to room temperature, centrifuge the product and wash it 4 times with deionized water until the pH of the filtrate is 7. Dry the product in an oven at 373 K for 12 h to obtain a mixed metal oxide precursor. Heat the mixed metal oxide precursor to 873 K in air at 5 K / min and hold for 2 h to obtain a mixed metal oxide. (2) Weigh 100 mg of the obtained mixed metal oxide, place it at the bottom of a quartz reactor and disperse it evenly in acetone. Keep it at 353 K for 0.5 h to completely evaporate the solvent and obtain a powder with a uniform and smooth surface. Under vacuum conditions (pressure less than 2 Pa), heat it to 513 K at 5 K / min and activate it for 1 h to remove impurities and residual solvent adsorbed on the catalyst surface. After cooling to room temperature, introduce 100 mbar methane gas (purity 99.999%) and finally irradiate it with a 300 W xenon lamp (wavelength range 300~2500 nm, PLS-SXE300D) for 20 min to obtain 100 mg of magnesium oxide and aluminum oxide mixed oxide catalyst supported on copper ruthenium alloy, which is named Cu 19.5 Ru 0.5 / MA (abbreviated as Cu) 19.5 Ru 0.5 ); (3) Same as step (3) in Example 1; (4) The conversion rate of methane was calculated to be 33.83 mmol·g. -1 ·h -1 The carbon monoxide formation rate was 27.17 mmol·g. -1 ·h -1 The carbon dioxide production rate was 0.14 mmol·g. -1 ·h -1 The rate of coke formation was 6.52 mmol·g. -1 ·h -1 .

[0021] Example 8 Preparation method of magnesium oxide and aluminum oxide mixed oxide catalyst supported on copper-ruthenium alloy and its application in photocatalytic chemical chain methane partial oxidation to syngas: (1) Weigh 1.830 g magnesium chloride hexahydrate (MgCl2•6H2O), 1.125 g aluminum nitrate (Al(NO3)3•9H2O), 0.6886 g copper nitrate (Cu(NO3)2•3H2O) and 39.2 mg ruthenium chloride (RuCl3•3H2O) and add them to 15 mL of deionized water. Stir the solution in an oil bath at 373 K. Then add 1.2 M sodium carbonate solution to the solution to adjust the pH to 8 and stir for 24 h. After the solution cools to room temperature, centrifuge the product and wash it 4 times with deionized water until the pH of the filtrate is 7. Dry the product in an oven at 373 K for 12 h to obtain a mixed metal oxide precursor. Heat the mixed metal oxide precursor to 873 K in air at 5 K / min and hold for 2 h to obtain a mixed metal oxide. (2) Weigh 100 mg of the obtained mixed metal oxide, place it at the bottom of a quartz reactor and disperse it evenly in acetone. Keep it at 353 K for 0.5 h to completely evaporate the solvent and obtain a powder with a uniform and smooth surface. Under vacuum conditions (pressure less than 2 Pa), heat it to 513 K at 5 K / min and activate it for 1 h to remove impurities and residual solvent adsorbed on the catalyst surface. After cooling to room temperature, introduce 100 mbar methane gas (purity 99.999%) and finally irradiate it with a 300 W xenon lamp (wavelength range 300~2500 nm, PLS-SXE300D) for 20 min to obtain 100 mg of magnesium oxide and aluminum oxide mixed oxide catalyst supported on copper ruthenium alloy, which is named Cu 19 Ru1 / MA (abbreviated as Cu) 19 Ru1); (3) Same as step (3) in Example 1; (4) The conversion rate of methane was calculated to be 38.06 mmol·g. -1 ·h -1 The carbon monoxide formation rate was 31.37 mmol·g. -1 ·h -1 The carbon dioxide production rate was 0.47 mmol·g. -1 ·h -1 The rate of coke formation was 6.22 mmol·g. -1 ·h -1 .

[0022] Example 9 Preparation method of magnesium oxide and aluminum oxide mixed oxide catalyst supported on copper-ruthenium alloy and its application in photocatalytic chemical chain methane partial oxidation to syngas: (1) Weigh 1.525 g magnesium chloride hexahydrate (MgCl2•6H2O), 0.938 g aluminum nitrate (Al(NO3)3•9H2O), 0.2392 g copper nitrate (Cu(NO3)2•3H2O) and 2.61 mg ruthenium chloride (RuCl3•3H2O) and add them to 15 mL of deionized water. Stir the solution in an oil bath at 373 K. Then add 1.2 M sodium carbonate solution to the solution to adjust the pH to 8 and stir for 24 h. After the solution cools to room temperature, centrifuge the product and wash it 4 times with deionized water until the pH of the filtrate is 7. Dry the product in an oven at 373 K for 12 h to obtain a mixed metal oxide precursor. Heat the mixed metal oxide precursor to 873 K in air at 5 K / min and keep it for 2 h to obtain a mixed metal oxide. (2) Weigh 100 mg of the obtained mixed metal oxide, place it at the bottom of the quartz reactor and disperse it evenly in acetone. Keep it at 353 K for 0.5 h to completely evaporate the solvent and obtain a powder with a uniform and smooth surface. Under vacuum conditions (pressure less than 2 Pa), heat it to 513 K at 5 K / min and activate it for 1 h to remove impurities and residual solvent adsorbed on the catalyst surface. After cooling to room temperature, introduce 100 mbar methane gas (purity 99.999%) and finally irradiate it with a 300 W xenon lamp (wavelength range 300~2500 nm, PLS-SXE300D) for 20 min to obtain 100 mg of magnesium oxide and aluminum oxide mixed oxide catalyst supported on copper ruthenium alloy, wherein n(Cu9Ru 0.09 ):n(MA)=1:10; (3) Same as step (3) in Example 1; (4) The conversion rate of methane was calculated to be 20.61 mmol·g. CuRu -1 ·h -1 The yield of carbon monoxide was 4.54%, and the yield of carbon dioxide was 1.98%.

[0023] Example 10 Preparation method of magnesium oxide and aluminum oxide mixed oxide catalyst supported on copper-ruthenium alloy and its application in photocatalytic chemical chain methane partial oxidation to syngas: (1) Weigh 2.288 g magnesium chloride hexahydrate (MgCl2•6H2O), 1.5 g aluminum nitrate (Al(NO3)3•9H2O), 0.7176 g copper nitrate (Cu(NO3)2•3H2O) and 7.84 mg ruthenium chloride (RuCl3•3H2O) and add them to 15 mL of deionized water. Stir the solution in an oil bath at 373 K. Then add 1.2 M sodium carbonate solution to the solution to adjust the pH to 8 and stir for 24 h. After the solution cools to room temperature, centrifuge the product and wash it 4 times with deionized water until the pH of the filtrate is 7. Dry the product in an oven at 373 K for 12 h to obtain a mixed metal oxide precursor. Heat the mixed metal oxide precursor to 873 K in air at 5 K / min and keep it for 2 h to obtain a mixed metal oxide. (2) Weigh 100 mg of the obtained mixed metal oxide, place it at the bottom of the quartz reactor and disperse it evenly in acetone. Keep it at 353 K for 0.5 h to completely evaporate the solvent and obtain a powder with a uniform and smooth surface. Under vacuum conditions (pressure less than 2 Pa), heat it to 513 K at 5 K / min and activate it for 1 h to remove impurities and residual solvent adsorbed on the catalyst surface. After cooling to room temperature, introduce 100 mbar methane gas (purity 99.999%) and finally irradiate it with a 300 W xenon lamp (wavelength range 300~2500 nm, PLS-SXE300D) for 20 min to obtain 100 mg of magnesium oxide and aluminum oxide mixed oxide catalyst supported on copper ruthenium alloy, wherein n(Cu 16.5 Ru 0.17 ):n(MA)=1:5; (3) Same as step (3) in Example 1; (4) The conversion rate of methane was calculated to be 29.33 mmol·g. CuRu -1 ·h -1 The yield of carbon monoxide was 10.52%, and the yield of carbon dioxide was 4.14%.

[0024] Example 11 Preparation method of magnesium oxide and aluminum oxide mixed oxide catalyst supported on copper-ruthenium alloy and its application in photocatalytic chemical chain methane partial oxidation to syngas: (1) Weigh 0.915 g magnesium chloride hexahydrate (MgCl2•6H2O), 0.563 g aluminum nitrate (Al(NO3)3•9H2O), 0.7176 g copper nitrate (Cu(NO3)2•3H2O) and 7.84 mg ruthenium chloride (RuCl3•3H2O) and add them to 15 mL of deionized water. Stir the solution in an oil bath at 373 K. Then add 1.2 M sodium carbonate solution to the solution to adjust the pH to 8 and stir for 24 h. After the solution cools to room temperature, centrifuge the product and wash it 4 times with deionized water until the pH of the filtrate is 7. Dry the product in an oven at 373 K for 12 h to obtain a mixed metal oxide precursor. Heat the mixed metal oxide precursor to 873 K in air at 5 K / min and hold for 2 h to obtain a mixed metal oxide. (2) Weigh 100 mg of the obtained mixed metal oxide, place it at the bottom of the quartz reactor and disperse it evenly in acetone. Keep it at 353 K for 0.5 h to completely evaporate the solvent and obtain a powder with a uniform and smooth surface. Under vacuum conditions (pressure less than 2 Pa), heat it to 513 K at 5 K / min and activate it for 1 h to remove impurities and residual solvent adsorbed on the catalyst surface. After cooling to room temperature, introduce 100 mbar methane gas (purity 99.999%) and finally irradiate it with a 300 W xenon lamp (wavelength range 300~2500 nm, PLS-SXE300D) for 20 min to obtain 100 mg of magnesium oxide and aluminum oxide mixed oxide catalyst supported on copper ruthenium alloy, wherein n(Cu 33 Ru 0.33 ):n(MA)=1:2; (3) Same as step (3) in Example 1; (4) The conversion rate of methane was calculated to be 33.81 mmol·g. CuRu -1 ·h -1 The yield of carbon monoxide was 41.51%, and the yield of carbon dioxide was 0.18%.

[0025] Example 12 Preparation method of magnesium oxide and aluminum oxide mixed oxide catalyst supported on copper-ruthenium alloy and its application in photocatalytic chemical chain methane partial oxidation to syngas: (1) Weigh 0.610 g magnesium chloride hexahydrate (MgCl2•6H2O), 0.375 g aluminum nitrate (Al(NO3)3•9H2O), 0.9568 g copper nitrate (Cu(NO3)2•3H2O) and 10.45 mg ruthenium chloride (RuCl3•3H2O) and add them to 15 mL of deionized water. Stir the solution in an oil bath at 373 K. Then add 1.2 M sodium carbonate solution to the solution to adjust the pH to 8 and stir for 24 h. After the solution cools to room temperature, centrifuge the product and wash it 4 times with deionized water until the pH of the filtrate is 7. Dry the product in an oven at 373 K for 12 h to obtain a mixed metal oxide precursor. Heat the mixed metal oxide precursor to 873 K in an air atmosphere at 5 K / min and hold for 2 h to obtain a mixed metal oxide. (2) Weigh 100 mg of the obtained mixed metal oxide, place it at the bottom of the quartz reactor and disperse it evenly in acetone. Keep it at 353 K for 0.5 h to completely evaporate the solvent and obtain a powder with a uniform and smooth surface. Under vacuum conditions (pressure less than 2 Pa), heat it to 513 K at 5 K / min and activate it for 1 h to remove impurities and residual solvent adsorbed on the catalyst surface. After cooling to room temperature, introduce 100 mbar methane gas (purity 99.999%) and finally irradiate it with a 300 W xenon lamp (wavelength range 300~2500 nm, PLS-SXE300D) for 20 min to obtain 100 mg of magnesium oxide and aluminum oxide mixed oxide catalyst supported on copper ruthenium alloy, wherein n(Cu 49.5 Ru 0.5 ):n(MA)=1:1; (3) Same as step (3) in Example 1; (4) The conversion rate of methane was calculated to be 18.04 mmol·g. CuRu -1 ·h -1 The yield of carbon monoxide was 44.37%, and the yield of carbon dioxide was 0.12%.

[0026] Example 13 Preparation method of magnesium oxide and aluminum oxide mixed oxide catalyst supported on copper-ruthenium alloy and its application in thermocatalytic chemical chain methane partial oxidation to syngas: (1) Same as step (1) in Example 1; (2) Same as step (2) in Example 1; (3) Weigh 20 mg of the prepared catalyst into a 25 mL beaker, add 10 mL of deionized water and sonicate to disperse it evenly; use spin coating to evenly coat the obtained dispersion onto the surface of a glass fiber membrane (Shanghai Xingya Purification Materials Factory), dry at 353 K for 0.5 h to obtain a catalyst membrane with a uniform and smooth surface; place the catalyst membrane at the bottom of a quartz reactor, heat it to 513 K at 5 K / min under vacuum conditions (pressure less than 2 Pa), and activate it for 1 h to remove impurities and residual solvents adsorbed on the catalyst surface; place the quartz reactor on a heating platform for preheating for 1 h, with the heating platform temperatures set to 200℃, 250℃, 300℃, 350℃, and 400℃ respectively (heating rate of 10℃ / min), and introduce 28.5 mbar of high-purity methane gas (purity 99.999%) into the quartz reactor for 5 hours. min; after the reaction is complete, the components of the product are quantitatively analyzed by gas chromatography (GC-2014C). 1 mL of gas is extracted from the quartz reactor using a gas-tight needle and injected into the gas chromatograph to obtain the peak area of ​​hydrogen. The peak area is then analyzed using a standard curve (…). Figure 3 (a) The amount of hydrogen produced can be calculated. Then, 1 mL of gas is extracted from the quartz reactor using a gas-tight needle and injected into a gas chromatograph to obtain the peak areas of methane, carbon monoxide, and carbon dioxide. The peak areas are then analyzed using a standard curve. Figure 3 (bd)) can calculate the amount of methane consumed and the amount of carbon monoxide and carbon dioxide produced. Then, the conversion rate of methane, the generation rate of carbon monoxide and carbon dioxide, and the generation rate of coke can be calculated using the above formula. (4) The conversion rate of methane at 200 °C is calculated to be 0.25 mmol·g. -1 ·h -1 The carbon dioxide production rate is 0.25 mmol·g. -1 ·h -1 The conversion rate of methane at 250 °C is 0.32 mmol·g. -1 ·h -1 The carbon dioxide production rate was 0.32 mmol·g. -1 ·h -1 The conversion rate of methane at 250 °C is 0.56 mmol·g. -1 ·h -1 The carbon dioxide production rate was 0.56 mmol·g. -1 ·h -1 The conversion rate of methane at 250 °C is 0.82 mmol·g. -1 ·h -1 The carbon dioxide production rate was 0.82 mmol·g. -1·h -1 The conversion rate of methane at 250 °C is 1.18 mmol·g. -1 ·h -1 The carbon dioxide production rate was 1.18 mmol·g. -1 ·h -1 .

[0027] Example 14 Preparation method of magnesium oxide and aluminum oxide mixed oxide catalyst supported on copper-ruthenium alloy and its application in photocatalytic chemical chain methane partial oxidation to syngas: (1) Same as step (1) in Example 1; (2) Same as step (2) in Example 1; (3) Same as step (3) in Example 1; (4) Same as step (4) in Example 1; (5) After the reaction is complete, the quartz reactor containing the catalyst is evacuated to a vacuum (pressure below 2 Pa). Then, 28.5 mbar of high-purity methane gas (99.999% purity) is introduced into the quartz reactor. A 300 W xenon lamp (wavelength range 300~2500 nm, PLS-SXE300D) is used to irradiate the reactor for photocatalytic chemical chain partial oxidation of methane to prepare syngas (carbon monoxide and hydrogen). The irradiation time is 5 min. After the reaction is complete, the composition of the product is quantitatively analyzed using gas chromatography (GC-2014C). 1 mL of gas is extracted from the quartz reactor using a gas-tight needle and injected into the gas chromatograph to obtain the peak area of ​​hydrogen. The peak area is then analyzed using a standard curve (…). Figure 3 (a) The amount of hydrogen produced can be calculated. Then, 1 mL of gas is extracted from the quartz reactor using a gas-tight needle and injected into a gas chromatograph to obtain the peak areas of methane, carbon monoxide, and carbon dioxide. The peak areas are then analyzed using a standard curve. Figure 3 (bd)) can calculate the amount of methane consumed and the amount of carbon monoxide and carbon dioxide produced. Then, the conversion rate of methane, the generation rate and yield of carbon monoxide and carbon dioxide, and the formation rate of coke can be calculated using the above formula.

[0028] (6) After repeating the above operation 10 times, the conversion rate of methane was observed to decrease significantly, which proved the necessity of supplementing lattice oxygen and also proved that the reaction was mediated by lattice oxygen.

[0029] Example 15 Preparation method of magnesium oxide and aluminum oxide mixed oxide catalyst supported on copper-ruthenium alloy and its application in photocatalytic chemical chain methane partial oxidation to syngas: (1) Same as step (1) in Example 1; (2) Same as step (2) in Example 1; (3) Same as step (3) in Example 1; (4) Same as step (4) in Example 1; (5) After the reaction, the quartz reactor containing the catalyst was first exposed to air for 5 min, and then its interior was evacuated to a vacuum (pressure below 2 Pa). Then, 28.5 mbar of high-purity methane gas (purity 99.999%) was introduced into the quartz reactor, and photocatalytic chemical chain partial oxidation of methane (carbon monoxide and hydrogen) was performed using a 300 W xenon lamp (wavelength range 300~2500 nm, PLS-SXE300D) for 5 min. After the reaction, the composition of the product was quantitatively analyzed using gas chromatography (GC-2014C). 1 mL of gas was extracted from the quartz reactor using a gas-tight needle and injected into the gas chromatograph to obtain the peak area of ​​hydrogen. The peak area was then analyzed using a standard curve (…). Figure 3 (a) The amount of hydrogen produced can be calculated. Then, 1 mL of gas is extracted from the quartz reactor using a gas-tight needle and injected into a gas chromatograph to obtain the peak areas of methane, carbon monoxide, and carbon dioxide. The peak areas are then analyzed using a standard curve. Figure 3 (bd)) can calculate the amount of methane consumed and the amount of carbon monoxide and carbon dioxide produced. Then, the conversion rate of methane, the generation rate and yield of carbon monoxide and carbon dioxide, and the formation rate of coke can be calculated using the above formula.

[0030] (6) After repeating the above operation 20 times, it was observed that the conversion rate of methane did not decrease significantly, which indicates that the catalyst has good cycle stability and further proves that the reaction is mediated by lattice oxygen.

[0031] The above examples illustrate that the mixed oxide of magnesium oxide and aluminum oxide supported on copper-ruthenium alloy has high catalytic activity in the photocatalytic partial oxidation of methane in a chemical chain reaction, wherein Cu 19.8 Ru 0.2 / MA exhibits the highest selectivity and metal utilization, and demonstrates good cycling stability, showing its broad application prospects in the photocatalytic chemical chain reaction of methane partial oxidation to syngas.

Claims

1. A method for preparing a copper-ruthenium alloy photocatalyst, comprising the following steps: (1) First, magnesium precursor, aluminum precursor, copper precursor and ruthenium precursor are added to deionized water and stirred in an oil bath at 353~373 K. Then, a precipitant is added and the pH is adjusted to 8~10. The mixture is stirred for 12~24 h to obtain a mixed solution. The amount of magnesium precursor is 0~2.288 g, the amount of aluminum precursor is 0~1.5 g, and the amounts of magnesium precursor and aluminum precursor are not both 0. The amount of copper precursor is 0.2392~0.9568 g, the amount of ruthenium precursor is 1.96~39.2 mg, and the ratio of the amount of precipitant to the amount of all metals in the precursor is 1:1~2. (2) After the mixture solution obtained in step (1) is cooled to room temperature, the product is centrifuged and washed with deionized water 4 to 6 times until the pH value of the filtrate is 7; after drying at 353 to 393 K for 12 to 24 h, a mixed metal oxide precursor is obtained; then the mixed metal oxide precursor is heated to 573 to 1073 K in air at a rate of 1 to 10 K / min and held for 2 to 4 h to obtain a mixed metal oxide; (3) Weigh the mixed metal oxide obtained in step (2) and disperse it uniformly in the solvent at a concentration of 1~10 mg / mL. Then, keep it at 323~373 K for 0.5~1 h to completely evaporate the solvent and obtain a powder with a uniform and smooth surface. Then, under vacuum conditions, heat it to 473~533 K at a rate of 1~10 K / min to activate it for 1~2 h to remove impurities and residual solvent adsorbed on the surface. After cooling to room temperature, introduce methane gas and finally irradiate it under a light source with a wavelength range of 300~2500 nm for 10~30 min to obtain a copper ruthenium alloy catalyst supported on a mixed oxide of magnesium oxide and aluminum oxide, or supported on magnesium oxide, or supported on aluminum oxide, which is the copper ruthenium alloy catalyst for photocatalytic partial oxidation of methane in a chemical chain.

2. The preparation method of a copper-ruthenium alloy photocatalyst as described in claim 1, characterized in that: In step 1), the magnesium precursor is one of magnesium chloride and magnesium nitrate, the aluminum precursor is one of aluminum nitrate and aluminum chloride, the copper precursor is one of copper nitrate and copper chloride, the ruthenium precursor is one of ruthenium chloride, ruthenium nitrate, ruthenium acetylacetone, and ruthenium dodecylcarbonyl, and the precipitant is one of sodium carbonate, sodium hydroxide, and ammonia.

3. The preparation method of a copper-ruthenium alloy photocatalyst as described in claim 1, characterized in that: In step 3), the solvent is one of anhydrous ethanol, deionized water, or acetone.

4. The preparation method of a copper-ruthenium alloy photocatalyst as described in claim 1, characterized in that: In step 3), the purity of the methane gas is 99.999%, and the pressure is 20~1000 mbar.

5. A copper-ruthenium alloy photocatalyst, characterized in that: It is prepared by the preparation method described in any one of claims 1 to 4.

6. The application of the copper-ruthenium alloy photocatalyst according to claim 5 in the photocatalytic chemical chain partial oxidation of methane to prepare syngas under mild conditions.

7. The application of the copper-ruthenium alloy photocatalyst as described in claim 6 in the photocatalytic partial oxidation of methane to syngas under mild conditions, characterized in that: The steps are as follows: (1) Disperse the copper-ruthenium alloy catalyst in a solvent at a concentration of 1~10 mg / mL; then spin-coat the obtained dispersion onto the surface of a glass fiber membrane and dry it at 323~373 K for 0.5~1 h to remove the solvent and obtain a catalyst membrane with a uniform and smooth surface. (2) Place the catalyst film obtained in step (1) at the bottom of the quartz reactor and heat it to 473-533 K at a rate of 1-10 K / min under vacuum conditions for 1-2 h to remove impurities and residual solvents adsorbed on the catalyst surface. (3) After the catalyst activated in step (2) is cooled to room temperature, high-purity methane gas is introduced into the quartz reactor and reacted for 0.5 to 120 min under the irradiation of a light source with a wavelength range of 300 to 2500 nm, thereby realizing the partial oxidation of methane in the photocatalytic chemical chain.

8. The application of the copper-ruthenium alloy photocatalyst as described in claim 7 in the photocatalytic partial oxidation of methane to syngas under mild conditions, characterized in that: The solvent in step (1) is anhydrous ethanol, deionized water or acetone; the vacuum condition in step (2) is a pressure of less than 2 Pa; the purity of the high-purity methane gas in step (3) is 99.999% and the pressure is 20~1000 mbar.

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