A method for catalytic steam reforming of methanol to produce hydrogen

Abstract

The present invention belongs to the field of hydrogen production, and discloses a method for catalytic steam reforming of methanol to produce hydrogen, that is, methanol steam undergoes a reforming reaction under the action of a composite catalyst containing four metal components of Cu, Ag, Zn, and Al to generate hydrogen. The CuAgZnAl catalyst continuously reacts in a fixed bed for 11 h under the conditions of an alcohol-water ratio of 1:1.5, 230 °C, and a feed rate of 79 kg·s / mol. The average methanol conversion rate is 83.4%, the average CO selectivity is 1.07%, the average hydrogen production is 0.091 mol / (g·h), and the stability of the CuAgZnAl catalyst is also very good. The addition of Ag improves the stability of the CuAgZnAl catalyst and reduces the CO selectivity. The developed CuAgZnAl catalyst of the present invention has industrial application value.

Description

Technical Field

[0001] The present invention belongs to the field of hydrogen production, and relates to a method for catalytic steam reforming of methanol to produce hydrogen. Specifically, it relates to a multi-component metal catalyst (CuAgZnAl), a preparation method of the catalyst, and an application of the catalyst in the production of hydrogen by steam reforming of methanol. Background Art

[0002] The overexploitation of fossil fuels has led to the gradual depletion of energy. A large amount of greenhouse gases are generated during the use of traditional petroleum and coal resources, exacerbating the problem of environmental pollution. China put forward the dual-carbon goal in 2020 and regarded it as a major development strategy of China. Fuel cell technology is known as one of the most competitive high-efficiency and clean power generation technologies in the 21st century, with a very bright application prospect, and is an important way to achieve "carbon peak" and "carbon neutrality".

[0003] Hydrogen fuel cells are applied to the transportation industry because of their extremely high energy density and power generation efficiency. However, due to the disadvantages of hydrogen being flammable, explosive and difficult to store, there are safety hazards during storage and transportation, resulting in great limitations in popularization in daily life.

[0004] Methanol is hailed as a "liquid sunshine" fuel because it can be prepared by means of synthesizing green hydrogen and carbon dioxide or biomass. Meanwhile, methanol is liquid at room temperature, which is convenient for storage and transportation. At the same time, compared with the current mainly used ethanol and methane for hydrogen production at 500-600 °C, methanol can efficiently produce hydrogen at 250 °C. Compared with fuels such as gasoline and metal hydrides, methanol has the advantages of being sulfur-free, having no strong carbon-carbon bonds, a high hydrogen-carbon ratio, and a low hydrogen production temperature. However, the electrochemically active of methanol is at least three orders of magnitude lower than that of hydrogen, and it is reported that the power generation efficiency of methanol is far less than that of hydrogen.

[0005] Therefore, based on methanol fuel cell technology, using methanol as a hydrogen carrier fuel, the concept of a reforming methanol fuel cell has been proposed internationally. Among them, reforming methanol fuel cells are mainly divided into two categories: The first category is that the hydrogen-rich gas obtained by reforming methanol is purified and then supplied to a low-temperature reaction stack (reaction temperature is 60-80 °C). However, due to the large volume of the purification device, such fuel cells usually have a high power density; The second category is that the hydrogen-rich gas obtained by reforming methanol is directly supplied to a high-temperature stack (reaction temperature is 150-200 °C) without purification. This type is also called an internal reforming methanol fuel cell. The internal reforming methanol fuel cell has relatively harsh operating conditions. Currently, the temperature required for methanol reforming to produce hydrogen conversion needs to reach 250-300 °C. High temperatures will damage the proton exchange membrane. It is necessary to control the temperature below 250 °C, and at the same time, reduce the selectivity of CO to prevent the membrane electrode from being poisoned by high-concentration CO, resulting in a decrease in the service life of the battery.

[0006] Traditional Cu-based catalysts are widely used in the hydrogen production reaction of methanol steam reforming. For example, the RP60 commercial catalyst of BASF Company in Germany is mainly composed of transition metals Cu, Zn, and Al. The CuZnAl2O3 catalyst has good activity at temperatures not lower than 250 °C, and its activity rapidly decreases at lower temperatures of 180 - 230 °C. In addition, the stability of the CuZnAl2O3 catalyst during use still needs to be further improved. 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 reported the reasons for the deactivation of the CuZnAl2O3 catalyst, including the oxidation, sintering, and carbon deposition of the metal active components. 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 constructed the CuO / ZnO / Ga2O3 catalyst. By adding Ga promoter, the catalyst shows high catalytic activity at a low temperature of 180 °C, which is 2.2 times the activity of the commercial catalyst RP60 under the same reaction conditions. However, the catalyst showed obvious deactivation after 30 hours of continuous reaction, and the conversion rate was lower than that of commercial RP60 at the 30th hour. Zhang S, Liu Y, Zhang M, et al. Sustainable production of hydrogen with high purity from methanol and water at low temperatures[J]. Nature Communications, 2022, 13(1): 5527 combined Pt metal with Ce porous nanorods to prepare the Pt / PN-CeO2 catalyst, achieving efficient conversion of methanol steam reforming at low temperatures with a CO selectivity of less than 1%.Lin L, Zhou W, Gao R, et al. Low-temperature hydrogen production from water and methanol using Pt / α-MoC catalysts[J]. Nature, 2017, 544(7648): 80-83. A series of Pt / α-MoC catalysts were synthesized and used to catalyze the low-temperature methanol reforming for hydrogen production, and good catalytic activity was also achieved. When preparing the Pt / α-MoC catalysts, it is necessary to control MoC as α-phase. However, α-MoC has unstable structure and is easy to be transformed into β-Mo2C. Once β-Mo2C is formed, the catalyst has almost no activity. Therefore, strict control of process conditions is required during the synthesis and maintenance processes.

[0007] In summary, the key to developing the reforming methanol fuel cell technology is to develop highly efficient catalysts. Transition metal catalysts have the most commercial large-scale promotion and application value with lower cost and good catalytic activity. However, due to problems such as low low-temperature activity, poor stability, and high CO selectivity, they currently cannot meet the requirements of the low-temperature steam reforming of methanol for hydrogen production. Although catalysts based on noble metals such as Pt and α-MoC can produce good catalytic activity at relatively low reaction temperatures, they have the disadvantages of high Pt cost and complex preparation and maintenance processes of α-MoC, which will limit their large-scale promotion and application. Summary of the Invention

[0008] In order to overcome the shortcomings and deficiencies of the prior art, the present invention provides a multi-metal catalyst of CuAgZnAl added with an Ag promoter, enabling it to have good catalytic activity and stability at low temperature and maintaining a low CO selectivity. The present invention adopts the form of combining silver and copper, and significant improvements are obtained in terms of cost, activity, and CO selectivity.

[0009] Taking the RP60 commercial catalyst of BASF Company in Germany as a control, at a reaction temperature of 230 °C, the conversion rate of methanol on the CuAgZnAl catalyst is higher than that of the RP60 commercial catalyst, and at the same time, the CO selectivity is lower than that of the RP60 commercial catalyst. As the reaction temperature increases, the CuAgZnAl catalyst still has catalytic activity up to 360 °C, while the RP60 commercial catalyst starts to rapidly deactivate from 320 °C. The present invention provides a CuAgZnAl catalyst for the steam reforming of methanol for hydrogen production, which has high reaction activity and low CO selectivity at a relatively low temperature of 200-230 °C.

[0010] The inventive concept of the present invention is as follows: Cu-based catalysts represented by the CuZnAl component generate catalytic activity after being reduced at high temperature before the reaction. The components of the reduced catalyst are easily partially oxidized in the hydrothermal reaction system, resulting in low catalytic activity, easy carbon deposition deactivation, and poor stability. Research results such as those by Li Zhang, Jingbo Mao, Shenmin Li, Jingmei Yi n, Xudong. Sun, Xinwen. Guo, Chunshan Song, Jinxia Zhou, "Hydrogenation of levulinic acid into gamma-valerolactone over in situ reduced CuAg bimetallic catalyst: Strategy and mechanism of preventing Cu leaching," Appl. Catal. B: Environ., 2018, 232(15), 1-10 show that Ag, as an electronic promoter, can promote the reduction of metals such as Cu and inhibit their oxidation. Introducing an Ag promoter into the CuZnAl component, the combination of Ag and Cu reduces the reduction temperature of Cu oxides, making it easier for Cu to maintain a low valence state during the reaction, resulting in excellent catalytic performance. As an electronic well, Ag can also modulate the electronic properties of Cu, Zn, and Al, thereby optimizing the catalytic activation function, enabling the catalyst to exhibit good catalytic activity at a lower temperature, while reducing CO selectivity, inhibiting carbon deposition, and improving the stability of the catalyst.

[0011] RP60 for industrial promotion is developed based on relatively inexpensive Cu, ZnO, and Al2O3 components. The main components of the CuAgZnAl catalyst developed in the present invention are also based on inexpensive Cu, ZnO, and Al2O3 components. The main innovation of the present invention is the combination of introducing Ag with the traditional CuZnAl catalyst. Ag is a relatively inexpensive component in the noble metal family, and the content of Ag in the CuAgZnAl catalyst is very low. Introducing Ag does not significantly increase the cost of the catalyst. However, a small amount of Ag improves the activity and stability of the catalyst, enhancing its application value.

[0012] The object of the present invention is achieved by the following technical solutions:

[0013] A method for catalytic steam reforming of methanol to produce hydrogen is realized by the following steps: Using methanol and an aqueous solution as raw materials, catalytic steam reforming of methanol to produce hydrogen is carried out in a fixed-bed reactor under the action of a CuAgZnAl catalyst.

[0014] The described CuAgZnAl catalyst has the following composition and preparation process: The components for catalytic reforming to produce hydrogen are composed of Cu, Ag, ZnO, and Al2O3. Among them, Cu is the main component, and Ag, ZnO, and Al2O3 mainly act as promoters. On the basis of CuZnAl, the introduction of Ag significantly improves the activity and stability of the catalyst. The molar ratios of the components in the catalyst are as follows:

[0015] Cu:Ag = 2:1 to 10:1

[0016] Cu:Zn = 1:4 to 4:1

[0017] Cu:Al = 1:1 to 10:1

[0018] This catalyst is prepared by the co-precipitation method. The typical operation steps are as follows:

[0019] (1) Preparation of the salt solution: Take a certain amount of Cu(NO3)2·3H2O, Zn(NO3)2·6H2O, Al(NO3)3·9H2O, and AgNO3 in a beaker, and dissolve them with deionized water to make a salt solution;

[0020] (2) Preparation of the precipitant: Take one of a certain amount of NaHCO3, Na2CO3, and NaOH in a beaker, and dissolve it with deionized water to make an alkaline solution with a concentration of 0.1 - 1.5 M, which is used as the precipitant;

[0021] (3) Co-precipitation: Precipitate the solution prepared in (1) with the precipitant prepared in (2). It can be reverse precipitation (the salt solution is dropped into the precipitant), forward precipitation (the precipitant is dropped into the salt solution), or concurrent precipitation (the salt solution and the precipitant are simultaneously dropped into the buffer solution). The pH value of the mixture at the end of precipitation is 5 - 10, and then continuously stir and age;

[0022] (4) Filtration: Filter the suspension obtained in step (3) to separate the solid, and wash it with deionized water;

[0023] (5) Drying: Place the solid obtained in step (4) in a forced-air drying oven to dry, and then grind it into a powder;

[0024] (6) Calcination: Put the powdered sample prepared in step (5) into a crucible and calcine it in air, nitrogen, or argon. The calcination temperature is 400 - 700 °C.

[0025] For the described catalytic reaction of steam reforming of methanol to produce hydrogen, the typical operation steps are as follows;

[0026] (1) Catalyst reduction: Reduce it with hydrogen, or a mixture of hydrogen and nitrogen, or a mixture of hydrogen and argon, and reduce it for 1 - 10 hours under the condition of 200 - 500 °C;

[0027] (2) Reaction: A mixture of methanol and water is pumped into a fixed-bed reactor. After preheating, the mixture enters the reaction tube, contacts with the catalyst, and undergoes a catalytic reaction; the molar ratio of methanol to water is 1:1 to 1:3; the reaction temperature is 200 - 280 °C; the catalyst dosage [catalyst mass (kg) divided by methanol feed rate (mol / s)] is 30 - 300 kg·s / mol;

[0028] (3) Product collection: After the reaction, the mixture is condensed to separate water and methanol, and the gaseous product is discharged from the device through a pipeline.

[0029] Furthermore, the molar ratio of each component in the synthesized CuAgZnAl catalyst is Cu:Zn:Ag:Al = 3:3:0.5:1.

[0030] Furthermore, the precipitant used for the synthesized CuAgZnAl catalyst is prepared with NaHCO3, and the concentration is 1.1 M.

[0031] Furthermore, for the preparation method of the synthesized CuAgZnAl catalyst, the precipitation method used is reverse precipitation, and the pH value at the end of titration is 6.5.

[0032] Furthermore, the dried powder obtained in step (5) of the synthesized CuAgZnAl catalyst is calcined in an air atmosphere at a temperature of 500 °C for 2 h;

[0033] Furthermore, the conditions for the methanol steam reforming to produce hydrogen reaction under the action of the CuAgZnAl catalyst are: the molar ratio of methanol to water is 1:1.5; the reaction temperature is 230 °C; the catalyst dosage is 79 kg·s / mol.

[0034] The present invention has the following advantages and effects compared with the prior art:

[0035] (1) Adding an Ag promoter to the CuZnAl catalyst significantly improves the conversion rate of methanol compared with the commercial catalyst RP60, while reducing the CO production amount, maintaining the CO selectivity at about 1%, and the catalyst has excellent stability. The CuAgZnAl catalyst catalyzes the methanol steam reforming to produce hydrogen reaction at 230 °C. The average conversion rate in the first 11 hours is 83.4%, and the CO selectivity is 1.07%. The reaction continues to 100 h, and the methanol conversion rate still remains above 80%, while the CO selectivity always remains at 1%. Under the same conditions, the average conversion rate of RP60 in the first 11 hours is 78.7%, and the CO selectivity is 1.93%.

[0036] (2) Except for Ag, the metals in the catalyst are all inexpensive, and the amount of Ag used is extremely small, so the overall cost of the catalyst is relatively low. The addition of Ag has an electronic effect with Cu, reducing the reduction temperature of oxidized Cu and promoting the Cu component to maintain a low valence state in the reaction system. The addition of a small amount of Ag makes the catalyst highly active and stable in low-temperature reactions, and its long service life can save the catalyst input cost.

[0037] (3) The CuAgZnAl catalyst is synthesized by the co-precipitation method, which is simple to prepare and suitable for large-scale industrial preparation.

[0038] In summary, when the CuAgZnAl catalyst is used in the catalytic steam reforming of methanol to hydrogen at low temperature, it has the characteristics of high reaction activity, low CO selectivity, and good stability. The preparation method of the CuAgZnAl catalyst is suitable for large-scale industrial preparation, and has obvious advantages and industrial application value. Specific implementation method

[0039] The present invention will be further described in detail below with reference to the embodiments, but the implementation manners of the present invention are not limited thereto. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can be purchased from chemical companies.

[0040] Example 1 Continuous reaction of CuAgZnAl catalyst

[0041] 1. Preparation of the catalyst: The CuAgZnAl catalyst is prepared by the co-precipitation method, and the specific steps are as follows:

[0042] (1) Preparation of the salt solution: Take 4.8439 g of Cu(NO3)2·3H2O, 5.6171 g of Zn(NO3)2·6H2O, 2.5458 g of Al(NO3)2·9H2O, and 0.5839 g of AgNO3, and dissolve them in 50 mL of deionized water to make a salt solution;

[0043] (2) Preparation of the alkali solution: Take 10.062 g of NaHCO3 and dissolve it in 100 mL of deionized water to make an alkali solution;

[0044] (3) Co-precipitation: Heat the solutions in steps (1) and (2) in a water bath at 40 °C for 10 min, slowly and uniformly add the salt solution in (1) to (2) within ten minutes, and stir vigorously at the same time; after precipitation, raise the temperature of the mixture to 65 °C in the water bath, and stir and age at this temperature for 90 min. Then filter while it is hot and wash three times with deionized water;

[0045] (4) Drying: Place the sample prepared in step (3) in a forced-air drying oven, dry it at 40 °C for 5 h, then dry it at 95 °C for 24 h, and grind it with an agate mortar until the sample becomes powder.

[0046] (5) Calcination: Put the powder obtained in step (4) in a crucible, place it in a muffle furnace, and heat it from room temperature to 500 °C at a rate of 5 °C / min under air, keep it at 500 °C for 2 h for calcination. When the temperature drops to room temperature, take out the sample and store it sealed.

[0047] 2. Reaction test: Use a fixed-bed reactor to conduct a continuous reaction test on the performance of the CuAgZnAl catalyst for the steam reforming of methanol to produce hydrogen. The specific steps are as follows:

[0048] (1) Loading the catalyst: Take the reaction tube of the fixed-bed reactor, put 1 g of catalyst (100 - 200 mesh) into it, and add quartz wool at both the upper and lower ends of the catalyst to fix the catalyst in the constant-temperature part of the tube. Place the reaction tube in the heating jacket and tighten both ends, and check the airtightness of the device.

[0049] (2) Pre-reducing the catalyst: After ensuring no air leakage, open the N2 valve, set the N2 flow rate to 10 mL / min, and turn on the condensation reflux device. Conduct a programmed temperature rise under an atmosphere of 10 mL / min N2 at a heating rate of 5 °C / min from room temperature to 260 °C. When the temperature reaches 260 °C, open the H2 gas path valve, set the H2 flow rate to 10 mL / min, and pre-reduce for 1 h at 260 °C. After the catalyst is reduced for 1 h, lower the temperature of the reactor to 230 °C, and at the same time close the hydrogen gas path valve.

[0050] (3) Reaction test: When the reaction bed temperature is constant at 230 °C, turn on the feed pump, set the feed rate to 0.05 mL / min. At this time, the feed amount is 79 kg·s / mol (the ratio of the catalyst dosage (kg) to the methanol feed amount (mol / s)). After the raw material is preheated and vaporized at 130 °C through the preheating tube, it is fed into the reaction tube together with 10 mL / min of N2 for reaction.

[0051] (4) Product analysis: The tail gas after the reaction first passes through a condensation tank to condense and remove water and methanol from the unreacted raw materials. The gas components after condensation are discharged from the tail gas of the fixed bed, connected to a six-port valve of a gas chromatograph, and analyzed for components by the TCD detector of the gas chromatograph after sampling.

[0052] Among them: The conversion rate of methanol = (the amount of carbon dioxide generated per minute + the amount of carbon monoxide generated per minute + the amount of methane generated per minute) / the amount of methanol aqueous solution fed per minute × 100%.

[0053] Selectivity of CO = amount of carbon monoxide generated per minute / (amount of carbon dioxide generated per minute + amount of carbon monoxide generated per minute) × 100%

[0054] H2 production = molar amount of hydrogen produced per hour / amount of catalyst used mol / (g·h)

[0055] The chromatographic analysis conditions were as follows: a thermal conductivity detector (TCD) was used, argon was used as the carrier gas, the internal standard method was used, and nitrogen was used as the internal standard gas.

[0056] 3. The reaction results are shown in Table 1.

[0057] Table 1 Continuous reaction results of CuAgZnAl catalyst for steam reforming of methanol at 230 °C

[0058]

[0059]

[0060] As can be seen from Example 1, when the reaction temperature was 230 °C during the 11-hour continuous reaction process, the activity of the CuAgZnAl catalyst was relatively stable. The average methanol conversion rate was 83.4%, the average CO selectivity was 1.07%, below 2%, and the average hydrogen production was 0.0908 mol / (g·h).

[0061] Comparative Example 1 Continuous reaction of RP60 commercial catalyst

[0062] 1. Preparation of the catalyst: Purchase the RP60 commercial catalyst from BASF Company in Germany, grind and screen it to obtain a powder between 100 and 200 mesh.

[0063] 2. Reaction test: Use a fixed-bed reactor to conduct a continuous reaction test on the performance of the RP60 catalyst for the steam reforming of methanol to produce hydrogen. The specific steps are the same as in Example 1.

[0064] 3. The reaction results are shown in Table 2.

[0065] Table 2 Continuous reaction results of RP60 commercial catalyst for steam reforming of methanol to produce hydrogen at 230 °C

[0066]

[0067]

[0068] As can be seen from Comparative Example 1, when the reaction temperature was 230 °C during the 11-hour continuous reaction process, the average methanol conversion rate catalyzed by the RP60 catalyst was 78.74%, the average CO selectivity was 1.93%, and the average hydrogen production was 0.0865 mol / (g·h).

[0069] Comparative analysis of Example 1 and Comparative Example 1 reveals that the reaction results show that under the same conditions, the CO selectivity on the CuAgZnAl catalyst of the present invention is approximately half of that on RP60, the average methanol conversion rate is 5% higher than that of RP60, and the hydrogen production also increases. The newly synthesized CuAgZnAl catalyst has high catalytic activity and lower CO selectivity than RP60. The CuAgZnAl catalyst proposed in this patent has high catalytic activity, low CO selectivity, and higher commercial application value.

[0070] As mentioned above, it is only the preferred specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, making equivalent substitutions or changes should be covered within the protection scope of the present invention.

Claims

1. A method for catalytic steam reforming of methanol to produce hydrogen, characterized in that, Using methanol: aqueous solution as raw materials, methanol steam reforming for hydrogen production is carried out in a fixed-bed reactor under the action of a CuAgZnAl catalyst; The CuAgZnAl catalyst has the following composition and preparation process: It is composed of Cu, Ag, ZnO and Al2O3. Among them, Cu is the main component, and Ag, ZnO and Al2O3 mainly act as promoters. On the basis of CuZnAl, the introduction of Ag significantly improves the activity and stability of the catalyst. The molar ratios of the components in the catalyst are: Cu:Ag = 2:1 to 10:1; Cu:Zn = 1:4 to 4:1; Cu:Al = 1:1 to 10:1; The catalytic methanol steam reforming for hydrogen production reaction includes the following steps: (1) Catalyst reduction: Reduction is carried out with hydrogen, or a mixture of hydrogen and nitrogen, or a mixture of hydrogen and argon, and reduced at 200 - 500 °C for 1 - 10 hours; (2) Reaction: A mixture of methanol and water is pumped into the fixed-bed reactor. After the mixture is preheated, it enters the reaction tube, contacts the catalyst, and undergoes a catalytic reaction; The molar ratio of methanol: water is 1:1 to 1:3; the reaction temperature is 200 - 280 °C; the catalyst dosage is 30 - 300 kg·s / mol; (3) Product collection: After the reaction, the mixture is condensed to separate water and methanol, and the gas product is discharged from the device through a pipeline.

2. The method for catalytic steam reforming of methanol to produce hydrogen according to claim 1, characterized in that The molar ratios of the components in the CuAgZnAl catalyst are Cu:Zn:Ag:Al = 3:3:0.5:

1.

3. The method for catalytic steam reforming of methanol to produce hydrogen according to claim 1, characterized in that, The conditions for the methanol steam reforming for hydrogen production reaction under the action of the CuAgZnAl catalyst are: the molar ratio of methanol: water is 1:1.5; the reaction temperature is 230 °C; the catalyst dosage is 79 kg·s / mol.

4. The method for catalytic steam reforming of methanol to produce hydrogen according to claim 1, characterized in that, The CuAgZnAl catalyst is prepared by the co-precipitation method, including the following steps: (1) Preparation of salt solution: Take Cu(NO3)2·3H2O, Zn(NO3)2·6H2O, Al(NO3)3·9H2O, and AgNO3 in a beaker, and dissolve them with deionized water to make a salt solution; (2) Preparation of precipitant: Take one of NaHCO3, Na2CO3, and NaOH in a beaker, and dissolve it with deionized water to make an alkali solution with a concentration of 0.1 - 1.5 M, which is used as a precipitant; (3) Co-precipitation: Precipitate the solution prepared in step (1) with the precipitant prepared in step (2). The pH value of the mixture at the end of precipitation is 5 - 10, and then continuously stir and age; (4) Filtration: Filter the suspension obtained in step (3) to separate the solid, and wash it with deionized water; (5) Drying: Place the solid obtained in step (4) in a blast drying oven for drying, and then grind it into a powder; (6) Calcination: Put the powdered sample prepared in step (5) into a crucible and calcine it in air, nitrogen or argon. The calcination temperature is 400 - 700 °C.

5. The method for catalytic steam reforming of methanol to produce hydrogen according to claim 4, characterized in that, The precipitant used for the CuAgZnAl catalyst synthesized in step (2) is prepared with NaHCO3 and has a concentration of 1.1 M.

6. The method for catalytic steam reforming of methanol to produce hydrogen according to claim 4, wherein, For the preparation method of the CuAgZnAl catalyst synthesized in the step (3), the precipitation method used is reverse precipitation, and the pH value at the end of titration is 6.

5.

7. The method for catalytic steam reforming of methanol to produce hydrogen according to claim 4, characterized in that, The dried powder obtained in the step (5) of the CuAgZnAl catalyst synthesized in the step (6) is calcined in an air atmosphere at a temperature of 500 °C for 2 h.

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