Graphene oxide supported multi-metal oxide thermal catalyst, preparation method thereof and application thereof

Abstract

The application discloses a graphene oxide loaded multi-metal oxide thermal catalyst and a preparation method and application thereof. The catalyst is composed of Cu, Ag, ZnO, Al2O3 and graphene oxide (GO), and a chemical expression formula of the catalyst is CuZnAgAl@GO, wherein Cu is a main component, Ag, ZnO and Al2O3 are auxiliary agents, and GO is a carrier. The CuZnAgAl@GO catalyst is synthesized by a deposition precipitation method, is simple in preparation and is suitable for large-scale industrialized preparation. The CuZnAgAl@GO catalyst is based on cheap Cu, ZnO and Al2O3 components, Ag is introduced and loaded on the graphene oxide, compared with a commercial catalyst RP60, the amount of CO generation is significantly reduced, the selectivity of CO is maintained at about 0.3%, meanwhile, the catalytic activity of the catalyst is equivalent to that of the commercial catalyst RP60, and the catalyst has excellent stability.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen production technology, specifically relating to a graphene oxide-supported multimetal oxide thermal catalyst, its preparation method, and its application. Background Technology

[0002] With increasing global concern about energy security and environmental pollution associated with fossil fuel use, the search for clean and renewable alternative energy sources has become a primary task in the global energy economic transformation. Hydrogen, as a clean and renewable energy source with extremely high calorific value, holds promise as an ideal alternative to fossil fuels. However, until the issues of hydrogen production and storage are effectively resolved, in-situ hydrogen production from liquid fuels combined with fuel cells remains a reasonable solution.

[0003] Methanol, known as "liquid sunshine" fuel, can be synthesized from green hydrogen and carbon dioxide or biomass. Methanol is liquid at room temperature, making it easy to store and transport. Compared to ethanol and methane, which are currently the main fuels for hydrogen production at 500–600°C, methanol can efficiently produce hydrogen at 250°C (Basile A, Iulianelli A, Longo T, Liguori S, De Falco M. Pd-based selective membrane state-of-the-art. In: De De FM, Marrelli L, Iaquaniello G, editors. Membrane Reactors for Hydrogen Production Processes. London: Springer, London; 2010. p. 21–55.). Compared to gasoline and metal hydrides, methanol has advantages such as being sulfur-free, lacking strong carbon-carbon bonds, having a high hydrogen-to-carbon ratio, and requiring a low hydrogen production temperature.

[0004] However, despite its numerous advantages, methanol's electrochemical activity is at least three orders of magnitude lower than that of hydrogen, resulting in significantly lower power generation efficiency compared to hydrogen (Madaswamy SL, Alothman AA, Al-Anazy MM, et al. Polyaniline-based nanocomposites for direct methanol fuel cells (DMFCs) - A Recent Review [J]. Journal of Industrial and Engineering Chemistry, 2021, 97, 79-94.). Therefore, methanol steam reforming for hydrogen production coupled with proton exchange membrane fuel cells holds promise for achieving integrated hydrogen production, storage, transportation, and real-time supply. This approach not only eliminates the safety hazards of high-pressure hydrogen storage but also reduces transportation costs, providing a new strategy for fuel cell applications. However, the application is limited by the use of proton exchange membranes, making the conditions for methanol steam reforming for hydrogen production quite demanding; currently, the temperature required for methanol reforming for hydrogen production is 250-300℃. High temperatures can damage proton exchange membranes, necessitating temperature control below 250°C. Simultaneously, CO selectivity must be reduced to prevent high-concentration CO poisoning of the membrane electrode assembly, which would shorten battery life. Developing a highly efficient catalyst with high activity at low temperatures has become a key solution.

[0005] Traditional Cu-based catalysts are widely used in methanol steam reforming for hydrogen production, such as the RP60 commercial catalyst from BASF in Germany, whose main components are transition metals Cu, Zn, and Al. CuZnAl2O3 catalysts exhibit good activity at temperatures not lower than 250°C, but their activity rapidly decreases at lower temperatures of 180-220°C. Furthermore, the stability of CuZnAl2O3 catalysts during use needs further improvement. Li H et al. reported the deactivation causes of CuZnAl2O3 catalysts, including oxidation, sintering, and carbon deposition of the active metal components (Li H, Ma C, Zou X, et al. On-board methanol catalytic reforming for hydrogen production-A review[J]. International Journal of Hydrogen Energy, 2021(7).DOI:10.1016 / j.ijhydene.2021.04.062). Ribeirinha P et al. constructed a CuO / ZnO / Ga2O3 catalyst. By adding Ga as a promoter, the catalyst exhibited high catalytic activity at a low temperature of 180℃, which was 2.2 times that of the commercial catalyst RP60 under the same reaction conditions (Ribeirinha P, Mateos-Pedrero C, Boaventura M, et al. CuO / ZnO / Ga2O3 catalyst for low temperature MSR reaction: Synthesis, characterization and kinetic model[J]. Applied Catalysis B: Environmental, 2018, 221:371-379). However, the catalyst showed significant deactivation after 30 hours of continuous reaction, with the conversion rate lower than that of commercial RP60 at the 30th hour.

[0006] In summary, the key to developing methanol reforming fuel cell technology lies in developing highly efficient catalysts. Transition metal catalysts have the greatest commercial value for large-scale application due to their lower cost and better catalytic activity. However, due to their low low-temperature activity, poor stability, and high CO selectivity, they cannot currently meet the requirements for methanol-to-hydrogen hydrogen production through low-temperature steam reforming. Summary of the Invention

[0007] To overcome the shortcomings and deficiencies of existing technologies, this invention provides a CuZnAgAl@GO multimetallic catalyst with graphene oxide as a support and Cu as the main component, exhibiting good catalytic activity and stability at low temperatures while maintaining low CO selectivity. Using the commercial RP60 catalyst from BASF (Germany) as a control, at a reaction temperature of 220°C, the methanol conversion rate on the CuZnAgAl@GO catalyst is higher than that of the RP60 commercial catalyst, while the CO selectivity is lower. This invention provides a CuZnAgAl@GO catalyst for methanol steam reforming to hydrogen production, exhibiting high activity and low CO selectivity at relatively low temperatures (180–220°C).

[0008] The inventive concept of this invention is to use graphene oxide as a carrier, leveraging graphene's unique two-dimensional planar structure and its excellent physical and chemical properties to provide a large specific surface area, allowing the metal components to be better dispersed on the graphene surface and avoiding the agglomeration of metal oxides. Simultaneously, as a carbon carrier material, graphene can in-situ reduce Cu oxides during the synthesis and calcination process, ensuring that more active species in the synthesis catalyst remain in Cu. 0 State. More Cu 0 -Cu + This is beneficial for methanol steam reforming. Characterization and calculations revealed that oxygen-containing intermediate species (CH3O* and HCOO*) can be better adsorbed on Cu. 0 -Cu + This site simultaneously promotes charge transfer between the catalyst and surface species, making it easier for the CH chemical bonds in methanol to break, thus promoting the forward reaction.

[0009] The CuZnAgAl@GO catalyst of this invention is based on inexpensive Cu, ZnO, and Al2O3 components, with Ag introduced and supported on graphene oxide. Ag is a relatively inexpensive component in the noble metal family, and its content in the CuZnAgAl@GO catalyst is very low; therefore, introducing Ag does not significantly increase the catalyst cost. In the CuZnAgAl@GO catalyst, besides the GO support, the Cu component can be reduced to Cu. 0 In terms of valence state, Ag, as an electronic additive, can also promote the reduction of metals such as Cu and inhibit their oxidation, thereby improving the catalyst activity and stability and enhancing its application value.

[0010] To achieve the above objectives, the technical solution of the present invention is as follows:

[0011] The present invention provides a graphene oxide supported polymetallic oxide thermal catalyst, wherein the catalyst is composed of Cu, Ag, ZnO, Al2O3 and graphene oxide (GO), and its chemical formula is CuZnAgAl@GO, wherein Cu is the main component, Ag, ZnO and Al2O3 are auxiliary agents, and GO is the support;

[0012] The molar ratio of each element in the catalyst is:

[0013] Cu:Ag = 2:1 to 10:1;

[0014] Cu:Zn = 1:4 to 4:1;

[0015] Cu:Al = 1:1 to 10:1;

[0016] The mass of GO is 1%-10% of the total mass of Cu, Ag, ZnO, and Al2O3.

[0017] Another aspect of the present invention provides a method for preparing the above-mentioned graphene oxide-supported polymetallic oxide thermal catalyst, the method comprising the following steps:

[0018] (1) Preparation of graphene oxide solution: dissolve graphene oxide in water and sonicate to obtain graphene oxide solution;

[0019] (2) Preparation of salt solution: Cu(NO3)2·3H2O, Zn(NO3)2·6H2O, Al(NO3)3·9H2O and AgNO3 are dissolved in deionized water to obtain salt solution;

[0020] (3) Precipitation: Using an alkaline solution as a precipitant, the graphene oxide solution obtained in step (1), the salt solution obtained in step (2), and the alkaline solution are mixed to carry out a precipitation reaction. When the precipitation is completed, the pH value of the mixture is 5 to 10. Then, the mixture is continuously stirred and aged for 1 to 1.5 hours.

[0021] Precipitation can be performed using reverse precipitation, forward precipitation, or co-current precipitation. Reverse precipitation involves mixing a graphene oxide solution and an alkaline solution, then adding a salt solution dropwise to the mixture. Forward precipitation involves mixing a graphene oxide solution and a salt solution, then adding a precipitant dropwise to the mixture. Co-current precipitation involves mixing a graphene oxide solution and a buffer solution (here, the buffer solution is deionized water), then simultaneously adding the precipitant and the salt solution dropwise to the mixture.

[0022] (4) Filtration: The suspension obtained in step (3) is filtered to separate the solids and washed with deionized water;

[0023] (5) Drying: Dry the solid obtained in step (4) and then grind it into powder;

[0024] (6) Calcination: The powder obtained in step (5) is placed in a crucible and calcined to obtain CuZnAgAl@GO catalyst.

[0025] In the above technical solution, the alkaline solution is further described as an aqueous solution of any one of NaHCO3, Na2CO3, and NaOH, with a concentration of 0.1 to 1.5 M, preferably an aqueous solution of NaHCO3 with a concentration of 1.1 M.

[0026] In the above technical solution, further, in step (3), the aging temperature is 45-95℃.

[0027] In the above technical solution, the calcination atmosphere is air, nitrogen or Ar, the calcination temperature is 400-700℃, and the calcination time is 1-4h.

[0028] This invention also provides a method for catalytic methanol steam reforming to produce hydrogen. Under the action of the above-mentioned CuZnAgAl@GO catalyst, the reaction conditions for methanol steam reforming to produce hydrogen are: methanol:water molar ratio of 1:1 to 1:3; reaction temperature of 200 to 280°C; and reaction volume hourly space velocity of 1000 to 12000 h⁻¹. -1 .

[0029] In the above technical solution, the specific steps of the method are as follows:

[0030] 1) Catalyst reduction: The CuZnAgAl@GO catalyst was reduced at 200–500 °C for 1–10 h under a reducing atmosphere;

[0031] 2) Reaction: A mixture of methanol and water is pumped into the fixed-bed reactor. After being preheated, the mixture enters the reaction tube and comes into contact with the catalyst to carry out a catalytic reaction.

[0032] 3) Product collection: The mixture after the reaction is discharged from the device through pipeline.

[0033] In the above technical solution, the reducing atmosphere is any one of hydrogen, a mixture of hydrogen and nitrogen, or a mixture of hydrogen and argon.

[0034] The beneficial effects of this invention are as follows:

[0035] (1) The CuZnAgAl@GO catalyst of this invention is based on inexpensive Cu, ZnO, and Al2O3 components, with Ag introduced and supported on graphene oxide. Compared with the commercial catalyst RP60, it significantly reduces CO generation while maintaining CO selectivity at around 0.3%, and also maintains catalytic activity comparable to the commercial catalyst RP60, and the catalyst exhibits excellent stability. The CuZnAgAl@GO catalyst catalyzes the methanol steam reforming reaction for hydrogen production at 220°C. In the first 10 hours, the average conversion rate is 60.92%, and the CO selectivity is 0.297%. Even after 100 hours, the methanol conversion rate remains above 55%, while the CO selectivity remains below 0.3%. Under the same conditions, RP60 has an average conversion rate of 67.384% and a CO selectivity of 0.745% in the first 10 hours.

[0036] (2) Except for Ag, all other metals in the catalyst of this invention are inexpensive, and the amount of Ag used is extremely small, resulting in a low overall cost of the catalyst. The addition of Ag has an electronic effect with Cu, which lowers the reduction temperature of the oxidized Cu and keeps the Cu component in a low valence state in the reaction system. The addition of a small amount of Ag makes the catalyst highly active and stable at low temperatures, and its long service life saves on catalyst input costs.

[0037] (3) The CuZnAgAl@GO catalyst of the present invention is synthesized by deposition precipitation method, which is simple to prepare and suitable for large-scale industrial preparation.

[0038] In summary, the CuZnAgAl@GO catalyst exhibits high reactivity, low CO selectivity, and good stability at low temperatures in the catalytic low-temperature methanol steam reforming reaction to produce hydrogen. The preparation method of the CuZnAgAl@GO catalyst is suitable for large-scale industrial production, demonstrating significant advantages and industrial application value. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0040] Unless otherwise specified, the experimental methods used in this invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can all be purchased from chemical companies.

[0041] Example 1

[0042] Continuous reaction of CuZnAgAl@GO catalyst

[0043] 1. Catalyst Preparation: In this example, the molar ratio of each component in the CuZnAgAl@GO catalyst is Cu:Zn:Ag:Al = 3:3:0.5:1. The CuZnAgAl@GO catalyst was prepared by a deposition precipitation method, and the specific steps are as follows:

[0044] (1) Preparation of graphene oxide solution: 10 wt% of the synthesized polymetallic oxide graphene oxide was placed in a beaker, water was added, and the solution was sonicated for 30 min to obtain a graphene oxide solution with a volume percentage of 3%.

[0045] Graphene oxide was prepared using a modified Hummers method, or commercial graphene oxide could be used. In this embodiment, the modified Hummers method was used: 230 mL of 98% concentrated sulfuric acid was added to a beaker containing 5 g of KNO3. Stirring was started, and the beaker was placed in an ice-water bath. When the ice-water bath temperature was ≤5℃, 10 g of natural flake graphite was slowly added to the beaker. After stirring for 2.5 h, 30 g of KMnO4 was added to the beaker within 10 min, while controlling the water bath temperature to ≤20℃. The water bath temperature was then increased to 35℃, and stirring was continued for 2 h. 460 mL of deionized water was then added. The beaker was then placed in an oil bath at 98℃ and stirred for 15 min. The beaker was then removed, and 1.4 L of deionized water and 25 mL of 30% H2O2 solution were added simultaneously. After standing, the graphene oxide separated into layers. The supernatant was filtered off, and the beaker was washed with water. This process was repeated 5-6 times, and the wet graphene oxide was obtained by centrifugation.

[0046] (2) Preparation of salt solution: Take 4.8439g Cu(NO3)2·3H2O, 5.6171g Zn(NO3)2·6H2O, 2.5458g Al(NO3)2·9H2O, and 0.5839g AgNO3, and dissolve them in 50mL of deionized water to prepare a salt solution;

[0047] (3) Preparation of alkaline solution: Take 10.062g NaHCO3 and dissolve it in 100mL of deionized water to prepare an alkaline solution;

[0048] (4) Deposition and precipitation: The graphene oxide solution obtained in step (1) and the alkaline solution obtained in step (3) are mixed and heated in a 40°C water bath for 10 minutes with the salt solution obtained in step (2). The salt solution is slowly and uniformly added to the mixture of graphene oxide and alkaline solution within ten minutes, while stirring vigorously until the pH is 6.5. After precipitation, the mixture is heated to 65°C in a water bath and aged at this temperature for 90 minutes.

[0049] (5) Filtration: While the solid is hot, filter it to separate the solid and wash it three times with deionized water;

[0050] (6) Drying: Place the sample obtained in step (5) in a forced-air drying oven and dry at 40°C for 5 hours, then dry at 85°C for 24 hours, and grind it into powder using an agate mortar.

[0051] (7) Calcination: Place the powder obtained in step (6) in a crucible and place it in a tube furnace. Under nitrogen protection, the temperature is increased from room temperature to 500℃ at a programmed rate of 5℃ / min. The sample is then calcined at 500℃ for 2 hours. When the temperature drops to room temperature, the sample is removed and sealed for storage.

[0052] 2. Reaction Testing: The performance of the CuZnAgAl@GO catalyst in the methanol steam reforming reaction to produce hydrogen was tested using a fixed-bed reactor in a continuous reaction. The specific steps were as follows:

[0053] (1) Catalyst loading: Take the reaction tube of the fixed bed reactor, put 1g of catalyst (120-160 mesh) into it, and add quartz wool to the upper and lower ends of the catalyst to fix the catalyst at a constant temperature in the tube. Put the reaction tube into the heating jacket and tighten the upper and lower ends. Check the airtightness of the device.

[0054] (2) Pre-reduction of catalyst: After ensuring no gas leakage, open the N2 valve, set the N2 flow rate to 10 mL / min, and open the condenser reflux device. In the atmosphere of 10 mL / min N2, perform programmed temperature increase from room temperature to 260℃ at a heating rate of 5℃ / min. When the temperature reaches 260℃, open the H2 gas path valve, set the H2 flow rate to 10 mL / min, and pre-reduce at 260℃ for 1 h. After the catalyst is reduced for 1 h, lower the reactor temperature to 220℃ and close the hydrogen gas path valve at the same time.

[0055] (3) Reaction Test: When the reaction bed temperature is constant at 220℃, turn on the feed pump and set the feed rate to 0.05mL / min. At this time, the volumetric space velocity [volume flow rate of methanol-water solution (m³ / min)] is... 3 ·h) divided by catalyst volume (m 3 )] is 6600h -1 After the raw material is preheated and vaporized at 130°C through a preheating tube, it is introduced into the reaction tube along with N2 at a flow rate of 10 mL / min to carry out the reaction.

[0056] (4) Product analysis: The tail gas after the reaction is discharged through the fixed bed and connected to the gas chromatograph 10-way valve. After sampling, the components are analyzed by coupling the TCD detector and FID detector of the gas chromatograph.

[0057] Where: Methanol conversion rate = (Amount of carbon dioxide generated per minute + Amount of carbon monoxide generated per minute + Amount of methane generated per minute) / Amount of methanol aqueous solution introduced per minute × 100%.

[0058] CO selectivity = Amount of carbon monoxide produced per minute / (Amount of carbon dioxide produced per minute + Amount of carbon monoxide produced per minute) × 100%

[0059] H2 production = Moles of hydrogen produced per hour / Amount of catalyst used (mol / (g·h))

[0060] The chromatographic analysis conditions were as follows: thermal conductivity detector (TCD) and flame ionization detector (FID) were used, with helium as the carrier gas and normalization method was employed.

[0061] 3. The reaction results are shown in Table 1.

[0062] Table 1. Results of CuZnAgAl@GO catalyst catalyzing continuous methanol steam reforming reaction at 220℃

[0063]

[0064] As can be seen from Example 1, when the reaction temperature is 220℃, the CuZnAgAl@GO catalyst has relatively stable activity during a continuous reaction process of 10h. The average methanol conversion rate is 60.92%, the average CO selectivity is 0.297% (below 0.5%), and the average hydrogen production is 0.084 mol / (g·h).

[0065] Example 2

[0066] Continuous reaction of CuZnAgAl@GO catalyst

[0067] 1. Catalyst preparation: The molar ratio of each component in the CuZnAgAl@GO catalyst in this embodiment is Cu:Zn:Ag:Al=4:3:0.5:1. The same preparation method as in Example 1 is used. The difference is that in step (2) of Example 2, the salt solution is prepared by taking 5.3554g Cu(NO3)2·3H2O, 4.9443g Zn(NO3)2·6H2O, 2.0782g Al(NO3)2·9H2O, and 0.4705g AgNO3 and dissolving them in 50mL of deionized water to prepare a salt solution.

[0068] 2. Reaction test: The performance of CuZnAgAl@GO catalyst in the methanol steam reforming to hydrogen production reaction was tested by continuous reaction in a fixed-bed reactor. The specific steps were the same as in Example 1.

[0069] 3. The reaction results are shown in Table 2.

[0070] Table 2. Results of continuous methanol-to-hydrogen reforming reaction catalyzed by CuZnAgAl@GO catalyst at 220℃.

[0071]

[0072] As can be seen from Example 2, when the reaction temperature is 220℃, the CuZnAgAl@GO catalyst has relatively stable activity during a continuous reaction process of 10h, with an average methanol conversion rate of 64.52%, an average CO selectivity of 0.66%, and an average hydrogen production of 0.089 mol / (g·h).

[0073] Comparative Example 1

[0074] Continuous reaction of RP60 commercial catalyst

[0075] 1. Catalyst preparation: Purchased RP60 commercial catalyst from BASF in Germany, and ground and sieved to obtain powder with a mesh size between 120-160.

[0076] 2. Reaction test: The performance of RP60 catalyst in the methanol steam reforming to hydrogen production reaction was tested by continuous reaction in a fixed-bed reactor. The specific steps were the same as in Example 1.

[0077] 3. The reaction results are shown in Table 3.

[0078] Table 3. Results of continuous methanol-to-hydrogen reforming reaction catalyzed by RP60 commercial catalyst at 220℃.

[0079]

[0080] As shown in Comparative Example 1, when the reaction temperature is 220℃, the average methanol conversion rate catalyzed by RP60 catalyst is 67.38%, the average CO selectivity is 0.75%, and the average hydrogen production is 0.094 mol / (g·h) during a continuous reaction process of 10 h.

[0081] Comparative Example 2

[0082] Continuous reaction of CuZnAgAl@GO catalyst

[0083] 1. Catalyst preparation: CuZnAgAl@GO catalyst was prepared by deposition precipitation method, and the specific steps were the same as in Example 1. The difference was that step (4) in Comparative Example 2 used an aging time of 120 min.

[0084] 2. Reaction test: The performance of CuZnAgAl@GO catalyst in the methanol steam reforming to hydrogen production reaction was tested by continuous reaction in a fixed-bed reactor. The specific steps were the same as in Example 1.

[0085] 3. The reaction results are shown in Table 4.

[0086] Table 4. Results of continuous methanol-to-hydrogen reforming reaction catalyzed by CuZnAgAl@GO catalyst at 220℃.

[0087]

[0088]

[0089] As can be seen from Comparative Example 2, keeping the content of each component constant and appropriately extending the aging time, the activity of the catalyst slightly decreases. When the reaction temperature is 220℃, during a continuous reaction process of 10h, the average methanol conversion rate is 43.70%, the average CO selectivity is 0.51%, and the average hydrogen production is 0.060 mol / (g·h).

[0090] As demonstrated in Examples 1 and 2, the CuZnAgAl@GO catalyst synthesized within the given scope of this invention exhibits good stability, high methanol conversion, and extremely low CO selectivity under different component ratios. Comparative analysis of Examples 1 and 1 reveals that, under comparable conditions, the CO selectivity of the CuZnAgAl@GO catalyst is approximately one-third that of the RP60 catalyst, while the average methanol conversion and hydrogen production are similar to those of RP60. Comparative analysis of Examples 1 and 2 also shows that changing the preparation conditions significantly affects the reaction activity; under comparable conditions, the reaction activity decreased by approximately 20%. The CuZnAgAl@GO catalyst proposed in this invention exhibits high catalytic activity and low CO selectivity at low temperatures, demonstrating greater commercial application value.

[0091] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A graphene oxide-supported polymetallic oxide thermal catalyst, characterized in that, The catalyst is composed of Cu, Ag, ZnO, Al2O3 and graphene oxide (GO), and its chemical formula is CuZnAgAl@GO, wherein Cu is the main component, Ag, ZnO and Al2O3 are auxiliary agents, and GO is the support. The molar ratio of the elements in the catalyst is: Cu:Ag = 2:1 to 10:1; Cu:Zn = 1:4 to 4:1; Cu:Al = 1:1 to 10:1; The mass of GO is 1%-10% of the total mass of Cu, Ag, ZnO, and Al2O3.

2. A method for preparing the graphene oxide-supported polymetallic oxide thermal catalyst according to claim 1, characterized in that, The method includes the following steps: (1) Preparation of graphene oxide solution: dissolve graphene oxide in water and sonicate to obtain graphene oxide solution; (2) Preparation of salt solution: Cu(NO3)2·3H2O, Zn(NO3)2·6H2O, Al(NO3)3·9H2O and AgNO3 are dissolved in deionized water to obtain salt solution; (3) Deposition and precipitation: The graphene oxide solution obtained in step (1) and the salt solution obtained in step (2) are mixed and precipitated with an alkaline solution. When the precipitation is finished, the pH value of the mixture is 5 to 10. Then, the mixture is continuously stirred and aged for 1 to 1.5 hours. (4) Filtration: The suspension obtained in step (3) is filtered to separate the solids and washed with deionized water; (5) Drying: Dry the solid obtained in step (4) and then grind it into powder; (6) Calcination: The powder obtained in step (5) is placed in a crucible and calcined to obtain CuZnAgAl@GO catalyst.

3. The preparation method according to claim 2, characterized in that, In step (3), the alkaline solution is an aqueous solution of any one of NaHCO3, Na2CO3, and NaOH, with a concentration of 0.1 to 1.5 M.

4. The preparation method according to claim 2, characterized in that, In step (3), the aging temperature is 45-95°C.

5. The preparation method according to claim 2, characterized in that, In step (6), the roasting atmosphere is air, nitrogen or Ar, the roasting temperature is 400-700℃, and the roasting time is 1-4h.

6. A method for producing hydrogen by catalytic steam reforming of methanol, characterized in that, Under the action of the CuZnAgAl@GO catalyst according to any one of claims 1-2, the conditions for the methanol steam reforming reaction to produce hydrogen are as follows: methanol:water molar ratio of 1:1 to 1:3; reaction temperature of 180 to 220°C; and reaction volume hourly space velocity of 1000 to 12000 h⁻¹. -1 .

7. The method according to claim 6, characterized in that, The specific steps of the method are as follows: 1) Catalyst reduction: The CuZnAgAl@GO catalyst was reduced at 200–500 °C for 1–10 h under a reducing atmosphere; 2) Reaction: A mixture of methanol and water is pumped into the fixed-bed reactor. After being preheated, the mixture enters the reaction tube and comes into contact with the catalyst to carry out a catalytic reaction. 3) Product collection: The mixture after the reaction is discharged from the device through pipeline.

8. The method according to claim 7, characterized in that, The reducing atmosphere is any one of hydrogen, a mixture of hydrogen and nitrogen, or a mixture of hydrogen and argon.

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