Methanol reforming hydrogen production catalyst as well as preparation method and application thereof

Abstract

The invention provides a methanol reforming hydrogen production catalyst as well as a preparation method and application thereof, and relates to the technical field of methanol hydrogen production. The preparation method specifically comprises the following steps: S1, adding a copper source, a zinc source, an aluminum source, a calcium source and a magnesium source into a water-alcohol solvent, heating to a constant temperature, adding a reducing agent and a coagulation agent, uniformly stirring and dispersing, condensing at the same time, and refluxing the evaporated solvent into a reaction solution for full reaction; and S2, after the reaction is finished, evaporating and concentrating, adding a defoaming agent and a viscosity reducer, and then drying, roasting and forming to obtain the catalyst. According to the preparation method, the plasticity of subsequent extrusion molding can be improved, in time, a large amount of synthetic waste liquid is not generated, and evaporated water and alcohol substances can be repeatedly used after being condensed. The methanol-to-hydrogen catalyst prepared by the method has the advantages of high specific surface area, more uniform dispersion of copper active substances, smaller size and excellent methanol reforming hydrogen production performance.

Description

Technical Field

[0001] This invention relates to the field of methanol-to-hydrogen technology, and in particular to a methanol reforming catalyst for hydrogen production, its preparation method, and its application. Background Technology

[0002] Currently, copper-zinc oxide catalysts are the most widely used catalysts for methanol reforming to produce hydrogen. Among them, copper-zinc-aluminum composite oxide catalysts can achieve efficient methanol-to-hydrogen conversion at relatively low temperatures (T≦250 ℃). These catalysts typically use high-specific-surface-area active alumina, cerium dioxide, or silica as supports to facilitate the catalytic decomposition of methanol into hydrogen and carbon dioxide by copper and zinc species. The particle size, dispersion, and chemical state of the copper active species directly affect the catalytic conversion efficiency, which is closely related to the preparation method. Co-precipitation is the most commonly used industrial preparation method for methanol reforming to produce hydrogen catalysts. This involves the co-precipitation reaction of the metal active component precursor under the action of an alkaline compound. Commonly used alkaline precipitants include sodium carbonate, sodium bicarbonate, and ammonia. CN118663340A prepared a low-copper methanol reforming hydrogen production catalyst using soluble metal salts as precursors and sodium carbonate and sodium bicarbonate as precipitants. CN118616051A prepared a copper-zinc-aluminum catalyst using metal oxides as precursors and supersaturated sodium carbonate as precipitant. CN119909678A prepared a copper-silicon catalyst using ammonia as precipitant. CN118162140A prepared a hydrotalcite-like copper-based methanol reforming hydrogen production catalyst using a co-precipitation method.

[0003] In large-scale preparation using the coprecipitation method, it is difficult to uniformly mix the components, resulting in a small specific surface area of ​​the catalyst, low dispersion and large particle size of copper active species, which affects the selectivity and durability of the catalyst. In addition, the coprecipitation process generates a large amount of waste alkali and washing liquid, and the environmental costs cannot be ignored.

[0004] Therefore, this invention is proposed. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a methanol reforming hydrogen production catalyst, its preparation method, and its application. The preparation method of this invention improves the plasticity of subsequent extrusion molding, and simultaneously avoids generating large amounts of synthesis waste liquid. The evaporated water and alcohol substances can be reused after condensation. The methanol-to-hydrogen catalyst prepared by this method has a high specific surface area, more uniform dispersion of copper active materials, and smaller size, exhibiting excellent methanol reforming hydrogen production performance.

[0006] In order to achieve the objective of this invention, the following technical solution is adopted: This invention provides a method for preparing a methanol reforming hydrogen production catalyst, comprising the following steps: S1. Add copper, zinc, aluminum, calcium and magnesium sources to water-alcohol solvent, raise to constant temperature, add reducing agent and flocculant, stir to disperse evenly, and condense at the same time. Reflux the evaporated solvent back to the reaction solution to carry out full reaction. S2. After the reaction is complete, evaporate and concentrate the solution, add defoamer and viscosity reducer, then dry, calcine and shape to obtain the final product.

[0007] Furthermore, the copper source, zinc source, aluminum source, calcium source, and magnesium source are compounds composed of metal cations of copper, zinc, aluminum, calcium, and magnesium and coordinating anions, and the compounds are completely or partially soluble in the water-alcohol solvent. The coordinating anion is any one or more of nitrate, hydrochloride, sulfate, acetate, carbonate, bicarbonate, perchlorate, cyanate, citrate, or oxalate.

[0008] Furthermore, the calcium source is any one or more of calcium carbonate, calcium nitrate, calcium chloride, and calcium sulfate.

[0009] Furthermore, the magnesium source is any one or more of magnesium nitrate, magnesium sulfate, and magnesium chloride.

[0010] Furthermore, the molar ratio of Cu:Zn:Al:Ca:Mg in the copper source, zinc source, aluminum source, calcium source and magnesium source is (1-16):1:(0.1-2.5):(0.02-0.2):(0.005-0.05).

[0011] Furthermore, the molar ratio of Cu:Zn:Al:Ca:Mg in the copper source, zinc source, aluminum source, calcium source and magnesium source is (4-7):1:(0.5-1.0):(0.05-0.1):(0.005-0.01).

[0012] Furthermore, the water-alcohol solvent is a mixture of water and alcohol, and the two are mutually soluble; The alcohol is any one or more of methanol, ethanol, propanol, isopropanol, allyl alcohol, or glycerol.

[0013] Furthermore, the alcohol is ethanol.

[0014] The mass ratio of water to alcohol is 1:(1-50).

[0015] Furthermore, the mass ratio of water to alcohol is 1:(1-5).

[0016] Furthermore, the reducing agent is a liquid phase, specifically one or more of the following: hydrazine hydrate, paraformaldehyde with a molecular weight less than 300, ethylene glycol, 1,2-propanediol, 1,2-butanediol, tetraethylene glycol trioxide, polyethylene glycol ethylenediamine with a molecular weight less than 10,000, diisobutylaluminum hydride, sodium borohydride, sodium cyanoborohydride, or urea.

[0017] Furthermore, the reducing agent is ethylene glycol.

[0018] Furthermore, the mass ratio of the reducing agent to the alcohol is 1:(0.1-10).

[0019] Furthermore, the mass ratio of the reducing agent to the alcohol is 1:(0.5-2).

[0020] Furthermore, the mass ratio of the reducing agent to the alcohol is 1:1.

[0021] Furthermore, the temperature at which the temperature is raised to a constant temperature in step S1 is 40℃-150℃; Furthermore, the temperature at which the temperature is raised to a constant temperature in step S1 is 80℃-120℃.

[0022] Furthermore, in step S1, the temperature at which the temperature is raised to a constant temperature is 85°C.

[0023] Furthermore, the flocculant is any one or more of tartaric acid, citric acid, succinic acid, oxalic acid, fumaric acid, malonic acid, benzoic acid, salicylic acid, or adipic acid.

[0024] Furthermore, the defoamer is any one or more of methanol, ethanol, diethylhexanol, isooctanol, isoamyl alcohol, diisobutylmethanol, ethylene glycol monostearate, glyceryl monostearate, or sorbitan ester.

[0025] Furthermore, the defoamer is methanol or ethanol.

[0026] Furthermore, the viscosity reducer is any one or more of guar gum powder, starch, cellulose, carbon powder, graphite powder, or gelatin.

[0027] Furthermore, in step S3, the constant temperature calcination temperature is 350-550 ℃, and the calcination time is 3-12 h.

[0028] The present invention also provides a hydrogen catalyst prepared by the above-described method for preparing methanol reforming hydrogen production catalyst.

[0029] The present invention also provides the application of the above-mentioned hydrogen catalyst in hydrogen transportation.

[0030] The present invention has the following technical effects: (1) The preparation method of the methanol steam reforming hydrogen production catalyst of the present invention is simple. The raw materials are directly prepared into copper-zinc-aluminum catalyst in one step, without generating washing waste liquid, and the cost is low, making it suitable for large-scale production.

[0031] (2) Compared with the precipitation method, the catalyst active components prepared by the liquid phase reduction-evaporation precipitation method of the present invention have smaller nano-sizes and more uniform distribution. The methanol conversion rate at 230 °C is close to 100%, and the hydrogen production rate is better than that of commercial samples.

[0032] (3) The preparation method provided by the present invention generates gases from the decomposition of organic matter and raw material anionic ligands during the drying and calcination process, which makes the catalyst form rich mesopores and has a larger specific surface area, which is beneficial to the transfer of reactants and heat. Attached Figure Description

[0033] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0034] Figure 1 : Microscopic morphology photographs of the catalyst prepared in Example 1; Figure 2 : Elemental distribution photograph of the catalyst prepared for implementation 1; Figure 3 : These are the performance evaluation results of the catalyst prepared in Example 1; Figure 4 : Nitrogen isotherm adsorption-desorption curve of the catalyst prepared in Example 1; Figure 5 The image shows the microstructure of the catalyst prepared in Example 2. The chain-like distribution forms cavities, which is beneficial for the methanol reforming to hydrogen production reaction. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0036] In a first aspect, the present invention provides a method for preparing a methanol reforming hydrogen production catalyst, comprising the following steps: S1. Add copper, zinc, aluminum, calcium and magnesium sources to water-alcohol solvent, raise to constant temperature, add reducing agent and flocculant, stir to disperse evenly, and condense at the same time. Reflux the evaporated solvent back to the reaction solution to carry out full reaction. S2. After the reaction is complete, evaporate and concentrate the solution, add defoamer and viscosity reducer, then dry, calcine, pulverize, grind and shape to obtain the final product.

[0037] In a heated water-alcohol system, the reducing agent partially reduces metal ions (especially Cu). 2+ This forms metal atoms or low-valence metal ions. Simultaneously, the flocculant (polybasic organic acid) acts as a complexing agent, reacting with metal ions (especially Zn). 2+ Al 3 + This forms a complex, allowing all metal components to be highly uniformly mixed at the molecular level.

[0038] Evaporation of the solvent increases the system concentration, disrupting the stability of the complex and prompting the reduced crystal nuclei to act as "seeds," initiating the co-precipitation of all metal components in a highly uniform manner. Reflux condensation ensures controllable reaction volume and concentration, preventing localized over-precipitation and component separation caused by complete solvent evaporation. Defoamers and viscosity reducers optimize the rheological properties of the concentrated slurry, making it easier to shape. The final calcination step is crucial: it allows organic acids, residual solvents, and decomposition products of the reducing agent to burn out, forming a rich porous structure; simultaneously, it transforms the amorphous precursor into a highly catalytically active copper-zinc-aluminum composite oxide crystalline phase.

[0039] This preparation method avoids the large amount of alkali metal salt-containing wastewater generated by traditional coprecipitation methods from the source, and the solvent can be recycled, truly realizing green chemistry. The process from solution complexation to coprecipitation greatly ensures the uniformity of mixing multiple metal elements such as Cu, Zn, Al, Ca, and Mg at the atomic scale, enabling the prepared product to have high performance. At the same time, the decomposition of organic matter during calcination leaves abundant mesopores and micropores for the catalyst, creating a high specific surface area, which is conducive to the diffusion of reactants and products. Finally, the reduction, precipitation, and concentration are integrated into a single reactor, simplifying the process and reducing equipment and operating costs.

[0040] In some embodiments, the copper source, zinc source, aluminum source, calcium source, and magnesium source are compounds composed of metal cations of copper, zinc, aluminum, calcium, and magnesium and coordinating anions, and the compounds are completely or partially soluble in the water-alcohol solvent. The coordinating anion is any one or more of nitrate, hydrochloride, sulfate, acetate, carbonate, bicarbonate, perchlorate, cyanate, citrate, or oxalate.

[0041] This invention utilizes the formation of coordination compounds or precipitates between organic acids and metal ions. As the solvent evaporates, the multi-component organometallic compounds gradually aggregate and precipitate, forming a gel state, thus preventing uneven distribution of components and large particle size in the product due to excessively rapid precipitation.

[0042] Most of the selected anions can decompose into gases and escape during the calcination process, without introducing impurity ions that are difficult to remove. This ensures the uniformity of the reaction starting point, avoids component inhomogeneity caused by the insolubility of some raw materials, and ensures the purity of the final catalyst.

[0043] In some embodiments, the calcium source is any one or more of calcium carbonate, calcium nitrate, calcium chloride, and calcium sulfate.

[0044] In some embodiments, the magnesium source is any one or more of magnesium nitrate, magnesium sulfate, and magnesium chloride.

[0045] In some embodiments, the molar ratio of Cu:Zn:Al:Ca:Mg in the copper source, zinc source, aluminum source, calcium source and magnesium source is (1-16):1:(0.1-2.5):(0.02-0.2):(0.005-0.05).

[0046] In some embodiments, the molar ratio of Cu:Zn:Al:Ca:Mg in the copper source, zinc source, aluminum source, calcium source and magnesium source is (4-7):1:(0.5-1.0):(0.05-0.1):(0.005-0.01).

[0047] Cu / Zn is the main catalytic active center, and its ratio directly affects the number of active sites and catalytic efficiency. In some embodiments, the water-alcohol solvent is a mixture of water and alcohol, and the two are mutually soluble; Al mainly forms the alumina framework, providing a large specific surface area and thermal stability, preventing the active components from sintering; Ca / Mg, as a "structural aid," is incorporated into the alumina lattice or located at grain boundaries, which can further improve the thermal stability and mechanical strength of the catalyst and prevent deactivation under high-temperature reaction conditions; this ratio range is an optimized golden ratio. Within this range, the catalyst can simultaneously possess high activity, high selectivity, high stability, and good mechanical strength.

[0048] The alcohol is any one or more of methanol, ethanol, propanol, isopropanol, allyl alcohol, or glycerol.

[0049] The mass ratio of water to alcohol is 1:(1-50); In some embodiments, the mass ratio of water to alcohol is 1:(1-10).

[0050] The addition of alcohols can alter the polarity of the solvent, increasing the solubility of certain organometallic salts while lowering the solvent's boiling point, making the "evaporation and concentration" step easier and more energy-efficient. Some selected alcohols (such as glycerol) can also act as weak reducing agents or complexing agents in the reaction. The reaction system of water and alcohol provides an optimized reaction medium, ensuring complete dissolution, high evaporation efficiency, and control over the size and morphology of metal particles.

[0051] In some embodiments, the reducing agent is a liquid phase, specifically one or more of the following: hydrazine hydrate, paraformaldehyde with a molecular weight less than 300, ethylene glycol, 1,2-propanediol, 1,2-butanediol, tetraethylene glycol trioxide, polyethylene glycol ethylenediamine with a molecular weight less than 10,000, diisobutylaluminum hydride, sodium borohydride, sodium cyanoborohydride, or urea.

[0052] In some embodiments, the reducing agent is ethylene glycol.

[0053] In some embodiments, the mass ratio of the reducing agent to the alcohol is 1:(0.1-10). In some embodiments, the mass ratio of the reducing agent to the alcohol is 1:(0.5-2).

[0054] In some embodiments, the mass ratio of the reducing agent to the alcohol is 1:1.

[0055] The role of the reducing agent is to controllably and partially reduce metal ions (mainly Cu). 2+ → Cu 0 or Cu + The process generates nanoscale metal nuclei as precipitate "seeds." Controlling the amount of reducing agent is crucial: too little leads to insufficient reduction and nucleation; too much causes excessive reduction of the metal into large agglomerates, disrupting uniformity. By controlling the degree of reduction, the size and number of active metal nanocrystal nuclei can be precisely controlled, ultimately regulating the dispersion and particle size of copper particles in the catalyst—a key to achieving high activity.

[0056] In some embodiments, the temperature at which the temperature is raised to a constant temperature in step S1 is 40°C-150°C; In some embodiments, the temperature at which the temperature is raised to a constant temperature in step S1 is 80°C-120°C.

[0057] In some embodiments, the temperature at which the temperature is raised to a constant temperature in step S1 is 85°C.

[0058] In this invention, the reaction temperature affects the reaction rate. Higher temperatures accelerate reduction and complexation reactions, solvent evaporation, and the agglomeration process. However, excessively high temperatures may lead to rapid nucleus growth and aggregation, compromising dispersibility. This temperature provides an optimal window that ensures sufficient reaction and evaporation rates while preventing excessive growth of nanoparticles. It is a crucial process parameter for achieving small-sized, highly dispersed active centers.

[0059] In some embodiments, the flocculant is any one or more of tartaric acid, citric acid, succinic acid, oxalic acid, fumaric acid, malonic acid, benzoic acid, salicylic acid, or adipic acid.

[0060] The flocculating agent is limited to specific polycarboxylic acids. These polycarboxylic acids have multiple coordination sites, enabling them to simultaneously complex with various metal ions, forming complex network complexes. This ensures a highly uniform distribution of active components, additives, and supports in the catalyst precursor and final product. During evaporation, these complex networks precipitate together, acting like a "molecular network" that uniformly "locks" all metal ions together, achieving superior mixing homogeneity.

[0061] In some embodiments, the defoamer is any one or more of methanol, ethanol, diethylhexanol, isooctanol, isoamyl alcohol, diisobutylmethanol, ethylene glycol monostearate, glyceryl monostearate, or sorbitan ester.

[0062] In some embodiments, the defoamer is methanol or ethanol.

[0063] In some embodiments, the viscosity reducer is any one or more of guar gum powder, starch, cellulose, carbon powder, graphite powder, or gelatin.

[0064] In some embodiments, the constant temperature calcination temperature in step S3 is 350-550 ℃, and the calcination time is 3-12 h.

[0065] The following is a detailed explanation using specific embodiments: Example 1 Weigh 5 kg of ethanol and 5 kg of deionized water (water to ethanol mass ratio 1:1) and add them to the reaction vessel, then start stirring. Add 7.5 kg of zinc acetate, 12 kg of aluminum nitrate, 40 kg of copper nitrate, 500 g of calcium chloride, and 85 g of magnesium hydroxide according to the ratio Cu:Zn:Al:Ca:Mg = 4.8:1:0.94:0.13:0.04. Raise the temperature to 90°C and start reflux. Slowly add 500 g of polyethylene glycol and 5 kg of ethylene glycol (alcohol / reducing agent = 1) to the reaction solution, stirring for 30 min. Then add 25 kg of oxalic acid and continue stirring at a constant temperature for 8 h. After the reaction is complete, evaporate the solvent using a condenser. During this process, slowly add 100 g of ethanol dropwise in batches for defoaming and add 200 g of guar gum powder to reduce the viscosity of the solution. After evaporation, the solution becomes gel-like and is transferred to a drying device to dry at 120°C for 8 hours. Then, it is transferred to a calcining device to calcine at 400°C for 5 hours. After cooling to room temperature, catalyst powder is obtained. After extrusion molding, it is made into a monolithic catalyst.

[0066] The catalyst powder exhibits a nanoparticle stacked morphology and possesses abundant pores, see Figure 1 .

[0067] The elements in the catalyst are evenly distributed, with no obvious separation or aggregation. Figure 2 .

[0068] Simulation test results show that the catalyst powder achieves a methanol conversion rate of 99.63% and a hydrogen production of 1144.37 mg / L at 230℃. 3 / (m 3 ×h), see Table 1; the performance at 215℃, 230℃, 245℃, 260℃, 275℃, and 280℃ is 96.43%, 99.63%, 99.86%, 99.91%, 99.88%, and 100%, respectively. Figure 3 .

[0069] The catalyst prepared in this example has a specific surface area of ​​33.55 m². 2 / g, its nitrogen isothermal adsorption-desorption curve is shown in Figure 4 Compared to Comparative Example 1, the catalyst prepared by the precipitation method has a specific surface area of ​​only 21.36 m². 2 / g.

[0070] Example 2 Based on the same synthesis scheme as in Example 1, the viscosity reducer was replaced by sodium methylcellulose instead of guar gum powder, while the stoichiometric ratio of the raw materials remained unchanged.

[0071] Sodium methylcellulose is a cellulose derivative with good solubility. Unlike guar gum, cellulose has a filamentous structure. When sodium methylcellulose is used as a viscosity reducer, the catalyst particles grow around the filamentous fiber structure and extend to form a more regular chain morphology, as shown in [reference needed]. Figure 5 .

[0072] from Figure 5 As can be seen, the cavities generated by the thermal decomposition of the viscosity reducer after calcination are beneficial for the transfer of reactants and heat.

[0073] Example 3 Weigh 5g of methanol and 5g of deionized water (water to methanol mass ratio 1:1) and add them to a beaker, then start stirring. Following the ratio of Cu:Zn:Al:Ca:Mg = 2.9:1:2.5:0.15:0.06, add 3.2g of zinc sulfate, 2.5g of alumina, 14g of copper nitrate, 0.17g of calcium oxide, and 0.07g of magnesium hydroxide. Heat to 85℃, then slowly add 10g of tetraethylene glycol (alcohol / reducing agent = 1:2), and reflux, stirring for 30 minutes. Subsequently, add 28g of oxalic acid and continue stirring at a constant temperature for 8 hours. After the reaction is complete, evaporate the solvent using a condenser. During this process, slowly add 5g of ethanol in batches for defoaming, and add 2g of starch to reduce the viscosity of the solution. After evaporation, the solution becomes gel-like. Transfer to a drying device and dry at 135℃ for 6 hours, then transfer to a calcining device and calcine at 380℃ for 6 hours. After cooling to room temperature, the catalyst powder is obtained. After extrusion molding, it is made into an integral catalyst.

[0074] The simulation test performance results are shown in Table 1.

[0075] Example 4 Using ethylene glycol as a reducing agent, a 100 ml solution was prepared at a mass ratio of deionized water:ethanol:ethylene glycol = 1:1:2, with 2% sodium carboxymethyl cellulose added as a viscosity reducer. Subsequently, zinc acetate, copper acetate, aluminum nitrate, calcium oxide, and magnesium oxide were added sequentially to the solution at a molar ratio of Cu:Zn:Al:Ca:Mg = 4:1:0.57:0.08:0.01. The mixture was heated to 85°C and refluxed for 60 min. Citric acid was added as a flocculant, equal to 2.05 times the total molar amount of the aforementioned metal elements. After the reaction was complete, the solvent was evaporated, methanol was added dropwise to defoam, and the gel-like product was transferred to a drying device and dried at 120°C. After calcination at 400°C for 5 h, catalyst powder was obtained. Graphite, silica sol, and water were added and mixed, and the resulting product was extruded to form an integral catalyst.

[0076] The simulated catalytic performance results are shown in Table 1.

[0077] Example 5 Compared to Example 4, replacing the defoamer with 2g of isoamyl alcohol achieves the same effect.

[0078] The simulated catalytic performance results are shown in Table 1.

[0079] Example 6 Weigh 20g of ethanol and 20g of deionized water (water to ethanol mass ratio 1:1), and start stirring. Add 8g of zinc acetate, 35g of copper acetate, 2.3g of aluminum oxide, 0.3g of calcium oxide, and 0.1g of magnesium oxide according to the ratio Cu:Zn:Al:Ca:Mg = 4.8:1:1.2:0.15:0.07. Stir and heat to 85℃, then slowly add 5g of ethylene glycol (alcohol / reducing agent = 4:1), turn on reflux, and stir for 30 minutes. Then, add 38g of oxalic acid for coagulation, and continue stirring at a constant temperature for 8 hours. After the reaction is complete, evaporate the solvent using a condenser. During this process, slowly add 5g of ethanol in batches for defoaming, and add 2g of guar gum powder to reduce the viscosity of the solution. After evaporation, the solution becomes gel-like. Transfer to a drying device and dry at 135℃ for 6 hours, then transfer to a calcining device and calcine at 400℃ for 5 hours. After cooling to room temperature, obtain the catalyst powder. After extrusion molding, it is made into an integral catalyst.

[0080] The simulated catalytic performance results are shown in Table 1.

[0081] Example 7 Weigh 500g of deionized water and 1000g of ethanol (water to alcohol mass ratio 1:2), add 1250g of oxalic acid, and heat to 85℃ until the oxalic acid is completely dissolved. Weigh 1500g of copper nitrate trihydrate, 680g of aluminum nitrate nonahydrate, 250g of zinc sulfate, 13g of calcium oxide, 5g of magnesium oxide, 500g of deionized water, and 200g of ethylene glycol (alcohol / reducing agent = 5:1) according to the ratio Cu:Zn:Al:Ca:Mg = 4.0:1:1.2:0.15:0.07, mix thoroughly, and then add dropwise to the above oxalic acid solution. After the addition is complete, continue stirring and reflux for 8 hours. After the reaction is complete, evaporate the solvent using a condenser. During the process, slowly add 50g of ethanol in batches for defoaming, and add 40g of guar gum powder to reduce the viscosity of the solution. After evaporation, the solution becomes gel-like and is transferred to a drying device at 135°C for 6 hours. It is then transferred to a calcining device at 400°C for 10 hours to obtain catalyst powder. This powder is then extruded to form a monolithic catalyst.

[0082] The simulated catalytic performance results are shown in Table 1.

[0083] Example 8 The catalyst powder is prepared into a monolithic catalyst through a molding extrusion die to better meet the needs of practical applications. In this example, the calcined catalyst powder is ground and mixed evenly, and 2% graphite powder, 5% zirconium sol, and a small amount of deionized water are added according to the mass of the catalyst powder. After thorough mixing, it is extruded into a Φ5*5mm cylindrical monolithic catalyst.

[0084] Example 9 Using the same preparation conditions as in Example 11, but with different extrusion dies, the monolithic catalyst can be spherical, cubic, cuboid, ellipsoid, or other elongated shapes.

[0085] Comparative Example 1 In this example, a precipitation method was used. According to the ratio of Cu:Zn:Al:Ca:Mg = 4.8:1:0.94:0.13:0.04, 7.5 kg of zinc acetate, 12 kg of aluminum nitrate, 40 kg of copper nitrate, 500 g of calcium chloride, and 85 g of magnesium chloride were dissolved in a 50% ethanol aqueous solution and stirred until dissolved. A saturated sodium carbonate solution was gradually added dropwise to adjust the pH to 8-10. After precipitation was complete, the reaction was continued with stirring for 8 hours. Subsequently, the mixture was filtered, and the filter cake was washed with deionized water until neutral. It was then dried at 120°C for 8 hours, and then transferred to a calcination apparatus for calcination at 400°C for 5 hours. After cooling to room temperature, catalyst powder was obtained. This powder was then extruded to form a monolithic catalyst.

[0086] Comparative Example 2 In this example, a grinding method was used. Following the stoichiometric ratio of the metal elements in the raw materials described in Example 1, 14.64g of copper oxide, 3.69g of zinc oxide, 1.33g of aluminum oxide, 0.2g of calcium oxide, and 0.04g of magnesium oxide were placed in a grinding apparatus. 10g of ethylene glycol, 5g of ethanol, 25g of deionized water, 23g of oxalic acid, 5g of citric acid, and 2g of guar gum powder were added. After all the additions were complete, the grinding reaction was continued for 4 hours. The product was then dried at 120℃ for 3 hours and calcined at 380℃ for 4 hours to obtain catalyst powder. This powder was then extruded to form an integral catalyst.

[0087] The simulated catalytic performance results are shown in Table 1.

[0088] Comparative Example 3 Compared to Example 4, the difference is that no reducing agent is added.

[0089] A 100 ml solution was prepared by mixing deionized water and ethanol at a mass ratio of 1:1, and 2% sodium hydroxymethyl cellulose was added as a viscosity reducer. Subsequently, zinc acetate, copper acetate, aluminum nitrate, calcium oxide, and magnesium oxide were added sequentially to the solution according to a molar ratio of Cu:Zn:Al:Ca:Mg = 4:1:0.6:0.08:0.01. The mixture was heated to 85°C and refluxed for 60 min. Citric acid was added as a flocculant, with a total molar ratio of 2.05 times the total molar amount of the aforementioned metal elements. After the reaction was complete, the solvent was evaporated, methanol was added dropwise to defoam, and the gel-like product was transferred to a drying device and dried at 120°C. After calcination at 400°C for 5 h, catalyst powder was obtained. Graphite, silica sol, and water were added and mixed, and the mixture was extruded to form a monolithic catalyst.

[0090] The simulated catalytic performance results are shown in Table 1.

[0091] Comparative Example 4 Compared to Example 3, the difference is that no flocculant is added.

[0092] Weigh 5g of methanol and 5g of deionized water into a beaker (water to alcohol mass ratio 1:1), start stirring, add 3.2g of zinc sulfate, 2.6g of alumina, 14g of copper nitrate, 0.17g of calcium oxide, and 0.07g of magnesium hydroxide, heat to 85℃, slowly add 10g of tetraethylene glycol, start reflux, and stir for 8 hours. After the reaction is complete, evaporate the solvent using a condenser. During the process, slowly add 5g of ethanol in batches for defoaming, and add 2g of starch to reduce the viscosity of the solution. After evaporation, the solution becomes gel-like, transfer it to a drying device and dry at 135℃ for 6 hours, then transfer it to a calcining device and calcine at 380℃ for 6 hours. After cooling to room temperature, the catalyst powder is obtained. After extrusion molding, it is made into a monolithic catalyst.

[0093] The simulation test performance results are shown in Table 1.

[0094] Comparative Example 5 Compared to Example 3, the difference is that no viscosity reducer was added. After the reaction was complete, the gel-like product adhered tightly to the reactor wall, resulting in a decrease in yield and hindering large-scale preparation.

[0095] Experimental Example: Catalyst Performance Verification One ml of the sample to be tested was placed in a quartz reaction tube, both ends were sealed with quartz wool, and the tube was placed in a simulation evaluation device. A 50% methanol aqueous solution was prepared and pumped into the vaporization chamber at a flow rate of 0.96 ml / h using a peristaltic pump to create a simulated atmosphere. The catalyst was heated to 230 °C, and the hydrogen and methanol content at the outlet was analyzed using gas chromatography-mass spectrometry (GC-MS) to calculate the hydrogen yield and methanol conversion rate. The calculation formulas are as follows: Methanol conversion efficiency: ; Hydrogen generation rate per unit volume of catalyst: ; Correction factor: .

[0096] Where F R F is the reforming tail gas flow rate (ml / h), F is the liquid feed rate (ml / h), ρmix is ​​the mixed liquid density (g / ml), w is the water-to-alcohol molar ratio, and V is the liquid concentration. cat Catalyst volume (m 3 CCO, CCO2, and CH2 represent the contents of CO, CO2, and H2 in the exhaust gas, respectively. T1 and P1 are the temperature (K) and pressure (kPa) for the actual reaction evaluation, while T2 and P2 are the temperature (273.15K) and pressure (101.325kPa) under standard conditions.

[0097] The test results are shown in Table 1. The methanol reforming hydrogen production catalyst and its preparation technology provided by this invention, after simulation testing, showed a methanol conversion efficiency exceeding 95% at 230 °C, with a maximum hydrogen generation rate of 1144.37 m³ / s per unit volume of catalyst. 3 / (m 3 The catalyst prepared by the *h) method has a higher specific surface area than that prepared by the precipitation method.

[0098] Table 1: Catalyst Performance Verification Results

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a methanol reforming hydrogen production catalyst, characterized in that, Includes the following steps: S1. Add copper, zinc, aluminum, calcium and magnesium sources to water-alcohol solvent, raise to constant temperature, add reducing agent and flocculant, stir to disperse evenly, and condense at the same time. Reflux the evaporated solvent back to the reaction solution to carry out full reaction. S2. After the reaction is complete, evaporate and concentrate the solution, add defoamer and viscosity reducer, then dry, calcine and shape to obtain the final product.

2. The method for preparing the methanol reforming hydrogen production catalyst according to claim 1, characterized in that, The copper source, zinc source, aluminum source, calcium source, and magnesium source are compounds composed of metal cations of copper, zinc, aluminum, calcium, and magnesium and coordinating anions, and the compounds can be completely or partially dissolved in the water-alcohol solvent. The coordinating anion is any one or more of nitrate, hydrochloride, sulfate, acetate, carbonate, bicarbonate, perchlorate, cyanate, citrate, or oxalate.

3. The method for preparing the methanol reforming hydrogen production catalyst according to claim 2, characterized in that, The molar ratio of Cu:Zn:Al:Ca:Mg in the copper source, zinc source, aluminum source, calcium source and magnesium source is (1-16):1:(0.1-2.5):(0.02-0.2):(0.005-0.05).

4. The method for preparing the methanol reforming hydrogen production catalyst according to claim 1, characterized in that, The water-alcohol solvent is a mixture of water and alcohol, and the two are mutually soluble; Wherein, the alcohol is any one or more selected from methanol, ethanol, propanol, isopropanol, allyl alcohol, or glycerol; The mass ratio of water to alcohol is 1:(1-50).

5. The method for preparing the methanol reforming hydrogen production catalyst according to claim 1, characterized in that, The reducing agent is a liquid phase, specifically one or more of the following: hydrazine hydrate, paraformaldehyde with a molecular weight less than 300, ethylene glycol, 1,2-propanediol, 1,2-butanediol, tetraethylene glycol trioxide, polyethylene glycol ethylenediamine with a molecular weight less than 10,000, diisobutylaluminum hydride, sodium borohydride, sodium cyanoborohydride, or urea.

6. The method for preparing the methanol reforming hydrogen production catalyst according to claim 1, characterized in that, The mass ratio of the reducing agent to the alcohol is 1:(0.1-10).

7. The method for preparing the methanol reforming hydrogen production catalyst according to claim 1, characterized in that, The temperature at which the temperature is raised to a constant temperature in step S1 is 40℃-150℃.

8. The method for preparing the methanol reforming hydrogen production catalyst according to claim 1, characterized in that, The flocculant is any one or more of tartaric acid, citric acid, succinic acid, oxalic acid, fumaric acid, malonic acid, benzoic acid, salicylic acid, or adipic acid.

9. A hydrogen catalyst prepared by the method for preparing a methanol reforming hydrogen production catalyst according to any one of claims 1-8.

10. The application of the hydrogen catalyst as described in claim 9 in hydrogen transportation.

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