Catalysts for hydrogen production from methanol steam reforming and their preparation method using oxalic acid sol-gel method

Abstract

This invention discloses a method for preparing a catalyst suitable for methanol steam reforming to produce hydrogen using the oxalic acid sol-gel method, comprising the following steps: adding soluble copper, aluminum, and zinc sources, a dispersant, and a metal oxide additive to deionized water; heating to completely dissolve the soluble copper, aluminum, and zinc sources to obtain a mixed solution; preparing a saturated oxalic acid solution; mixing the saturated oxalic acid solution with the mixed solution to completely dissolve the metal oxide additive; waiting for the solution to exhibit a uniform color; evaporating and concentrating the solution to a sol-gel state; adding guar gum powder to reduce viscosity; drying and then calcining to obtain the catalyst. This invention's oxalic acid sol-gel method innovatively employs a "one-step direct synthesis method," eliminating solid-liquid separation and washing steps, shortening the preparation cycle, and achieving a high methanol conversion rate after optimizing the copper content.

Description

Technical Field

[0001] This invention belongs to the field of active catalyst technology for methanol steam reforming to produce hydrogen, specifically relating to an oxalic acid sol-gel method for preparing a catalyst suitable for low-temperature methanol steam reforming to produce hydrogen, and the catalyst prepared by this oxalic acid sol-gel method suitable for low-temperature methanol steam reforming to produce hydrogen. Background Technology

[0002] my country's fossil resources are characterized by abundant coal, limited gas, and scarce oil, resulting in a high dependence on imported oil and posing a severe challenge to energy security. Faced with global energy shortages and environmental pollution, developing hydrogen energy, with its wide availability, high energy density, and environmentally friendly characteristics, not only has significant energy value but also profound strategic implications. However, hydrogen energy development faces safety challenges and cost bottlenecks in hydrogen production, storage, and transportation. The "coal-methanol-hydrogen" on-site hydrogen production route offers an innovative solution to this challenge.

[0003] Methanol, with its small molecular weight (32.04 g / mol), high hydrogen content (12.5 wt%), and stability at room temperature and pressure, is an ideal hydrogen energy carrier. my country has abundant methanol resources, laying a solid foundation for the methanol economy. As the core technology of this system, methanol steam reforming (MSR) achieves efficient on-site hydrogen production by circumventing the long-distance storage and transportation challenges of traditional hydrogen energy. While this technology can be applied in multiple scenarios with fuel cells, it has limitations such as high reaction temperature (250-300°C), slow start-up, high CO content as a byproduct, and low thermal efficiency.

[0004] The reaction mechanism of MSR is as follows: CH3OH + H2O → 3H2 + CO2 CH3OH → 2H2 + CO CO + H₂O → H₂ + CO₂ To address the aforementioned issues, low-temperature methanol-water reforming technology has emerged. This system comprises two main branches: low-temperature methanol-water vapor reforming (LT-MSR) and liquid-phase methanol-water reforming. By controlling the reaction temperature below 200°C, the preheating time is significantly shortened (by more than 40% compared to traditional processes), effectively suppressing side reactions. Studies have shown that this technology can improve CO selectivity to over 90% while maintaining a hydrogen production rate comparable to high-temperature processes (>3.0 L / min·gcat), providing crucial technological support for the commercial application of hydrogen energy.

[0005] The key to developing the MSR process lies in the catalyst. Domestically, companies producing MSR catalysts include the Lanzhou Institute of Chemical Physics of the Chinese Academy of Sciences and Sichuan Shutai Chemical Technology Co., Ltd., while internationally, companies producing MSR catalysts include BASF (Germany), Clarient (Switzerland), and ICI (Imperial Chemical Industries Ltd) (UK). Commercially available catalysts, at appropriate operating temperatures (250~350°C), exhibit high methanol conversion rates, good selectivity, and long lifespans.

[0006] Cu-based catalysts are widely used in the MSR field due to their low cost and high activity. Among them, CuZnAlOx catalysts prepared by co-precipitation or precipitation-deposition methods have been commercialized. The main components of CuZnAlOx are CuO, ZnO and Al2O3, and their composition ratio varies from manufacturer to manufacturer.

[0007] Coprecipitation is the most commonly used industrial preparation method for methanol reforming hydrogen production catalysts. This involves a coprecipitation 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. For example, patent CN118663340A prepared a low-copper methanol reforming hydrogen production catalyst using a soluble metal salt as a precursor and sodium carbonate and sodium bicarbonate as precipitants. The active component Cu in copper-based catalysts has poor metallic stability, and its performance is affected by changes in the copper valence state. The main causes of deactivation of copper-based catalysts include changes in the valence state of the active metal, coke deposition, or thermal sintering. Patent CN120714637A achieved a metal element-doped zinc-aluminum spinel catalyst for methanol reforming hydrogen production through a hydrothermal method. This catalyst exhibits high conversion rate, high hydrogen yield, and good anti-sintering ability, effectively extending the catalyst's lifespan. However, the spinel catalyst formed in this patent has a low specific surface area and low utilization rate of the internal catalyst active component. Patent CN120695859A provides a Cu / MoC methanol reforming molybdenum carbide-based catalyst for hydrogen production, which effectively promotes the formation of α-MoC crystal phase during the carbonization process of the molybdenum carbide-based catalyst, greatly improves the dispersion of active components on the support surface, and gives the catalyst good low-temperature activity and hydrogen production efficiency. At the same time, the catalyst also has good stability and low CO selectivity. However, the MoC used in this patent is expensive, and copper needs to be combined with zinc to better exert its activity and durability.

[0008] However, optimizing the activity of Cu-based catalysts is a multi-dimensional problem, involving key strategies such as synthesis methods, structural design, and elemental doping. Studies have shown that the specific surface area (especially that of Cu), particle size, and dispersion are the core factors affecting the activity, and all three are significantly positively correlated with the activity. Traditional co-precipitation methods, due to uneven micro-mixing, easily lead to uneven grain distribution, low specific surface area, and agglomeration of active components.

[0009] The above background information is provided only to assist in understanding the inventive concept and technical solution of this invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above information was disclosed before the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Summary of the Invention

[0010] In view of this, in order to overcome the shortcomings of the prior art, the object of the present invention is to provide a method for preparing an oxalic acid sol-gel method for a catalyst suitable for low-temperature methanol steam reforming to produce hydrogen.

[0011] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a catalyst suitable for methanol steam reforming to produce hydrogen via an oxalic acid sol-gel method, characterized by comprising the following steps: Soluble copper, aluminum, and zinc sources, along with dispersants and metal oxide additives, are added to deionized water and heated to completely dissolve the soluble copper, aluminum, and zinc sources, resulting in a mixed solution. Prepare a saturated oxalic acid solution; The saturated oxalic acid solution was mixed with the mixed solution, and the metal oxide additive was completely dissolved. When the solution showed a uniform color, it was evaporated and concentrated to a sol-gel state. Guava powder was added to reduce viscosity, and after drying, it was calcined to obtain the catalyst.

[0012] According to some preferred embodiments of the present invention, the copper source, zinc source, aluminum source and metal oxide additive are fed in a molar ratio of 1:0.15~0.35:0.1~0.3:0.01~0.05.

[0013] According to some preferred embodiments of the invention, the soluble copper source comprises copper nitrate; the soluble aluminum source comprises aluminum nitrate; the soluble zinc source comprises zinc sulfate; the dispersant comprises ethylene glycol and / or ethanol; and the auxiliary metal oxide comprises an oxide containing calcium and / or magnesium. The calcium-containing oxide is calcium oxide; the magnesium-containing oxide is magnesium oxide, which dissolves in a saturated solution containing oxalic acid.

[0014] According to some preferred embodiments of the invention, the dispersant comprises ethylene glycol and ethanol; the mass ratio of ethylene glycol to ethanol is 1:0.8-1.2.

[0015] According to some preferred embodiments of the invention, the heating is to raise the temperature of the mixed solution system to 80-90°C.

[0016] According to some preferred embodiments of the present invention, the preparation of the saturated oxalic acid solution is carried out at 80-90°C.

[0017] According to some preferred embodiments of the present invention, the oxalic acid content in the saturated oxalic acid solution is 1.05-1.2 times the theoretical value for the complete reaction of copper, zinc, and aluminum ions with oxalic acid.

[0018] According to some preferred embodiments of the invention, the reaction is carried out under reflux for 8-10 hours.

[0019] According to some preferred embodiments of the present invention, the amount of guar gum powder added is 1.5%-2.5% of the total mass of the system.

[0020] According to some preferred embodiments of the invention, the drying process is carried out at 120-150°C.

[0021] According to some preferred embodiments of the invention, the calcination treatment is performed at 350-450°C for 3-8 hours.

[0022] The present invention also provides a method for preparing a catalyst suitable for low-temperature methanol steam reforming to produce hydrogen using the oxalic acid sol-gel method described above.

[0023] According to some preferred embodiments of the present invention, the catalyst comprises alumina, zinc oxide, copper oxide, and metal oxide additives; by weight, the catalyst comprises 5-10 parts of alumina, 8-20 parts of zinc oxide, 65-85 parts of copper oxide, and 0.01-2 parts of metal oxide additives.

[0024] Due to the adoption of the above technical solutions, compared with the prior art, the oxalic acid sol-gel method for preparing catalysts suitable for low-temperature methanol steam reforming to produce hydrogen has the following advantages: (1) Breakthrough in low-temperature and high-efficiency catalytic performance: The catalyst prepared by the oxalic acid sol-gel method of this invention achieves a methanol conversion rate of over 99.22% and a CO conversion rate of over 6.53% at 230℃, with a hydrogen generation rate of 1074.34 m³ / s per unit volume of catalyst. 3 / (m 3 The efficiency (*h) is significantly better than that of traditional CuZnAlOx catalysts (requiring 250~350℃).

[0025] (2) The oxalic acid sol-gel method of the present invention is an innovative "one-step direct synthesis method", which eliminates the solid-liquid separation and washing steps, shortens the preparation cycle, and achieves a high methanol conversion rate after the copper content is optimized. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 The image shows the microstructure of the CuZnAl-RJ catalyst prepared by the oxalic acid sol-gel method in Example 1 of this invention. Figure 2 The elemental distribution diagram of the CuZnAl-RJ catalyst prepared by the oxalic acid sol-gel method in Example 1 of this invention is shown. Figure 3 The nitrogen adsorption-desorption curves are shown for the CuZnAl-RJ catalyst prepared by the oxalic acid sol-gel method in Example 1 of this invention. Detailed Implementation

[0028] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0029] This invention relates to the preparation of oxalic acid sol-gel method for low-temperature methanol reforming hydrogen production catalysts, specifically copper-zinc-aluminum composite oxide catalysts. The main raw materials include copper, aluminum, zinc, magnesium, and calcium sources, as detailed in Table 1.

[0030] Table 1. Main Chemical Reagents, Specifications, and Manufacturers Given that the precipitation method involves solid-liquid separation and filter cake washing, which affect the preparation cycle, the preparation method of the catalyst suitable for low-temperature methanol steam reforming to produce hydrogen in this invention is the oxalic acid sol-gel method, which specifically includes the following steps: Soluble copper, aluminum, and zinc sources, along with a dispersant and metal oxide additives, are added to deionized water. The mixture is heated until the soluble copper, aluminum, and zinc sources completely dissolve, yielding a mixed solution. Simultaneously, a saturated oxalic acid solution is prepared. The mixed solution is then mixed with the oxalic acid solution, allowing the metal oxide additives to completely dissolve. Simultaneously, the copper, zinc, and aluminum elements slowly react with the oxalic acid to form a sol-gel product. Subsequently, excess water is evaporated by heating, followed by drying and calcination to obtain methanol reforming hydrogen production catalyst powder. The metal oxide additives are calcium and / or magnesium sources, serving as additive components, such as calcium oxide and magnesium oxide. The catalyst in this invention primarily consists of copper, zinc, and aluminum. The calcium oxide provided by the calcium source enhances the structural strength during catalyst calcination, while the magnesium oxide provided by the magnesium source improves the catalyst's activity.

[0031] Preferably, the copper source, zinc source, aluminum source, and metal oxide additive are fed in a molar ratio of 1:0.15~0.35:0.1~0.3:0.01~0.05. Soluble copper sources include copper nitrate; soluble aluminum sources include aluminum nitrate; soluble zinc sources include zinc sulfate; dispersants include ethylene glycol and / or ethanol; and the metal oxide additive includes oxides containing calcium and / or magnesium. The calcium-containing oxide is calcium oxide; and the magnesium-containing oxide is magnesium oxide. The mass ratio of ethylene glycol to ethanol is 1:0.8-1.2; the temperature of the mixed solution system is raised to 80-90℃; the oxalic acid saturated solution is prepared at 80-90℃; the theoretical oxalic acid content of the oxalic acid saturated solution is 1.05-1.2N; the reaction is carried out under reflux for 8-10 hours; the drying treatment is carried out at 120-150℃; the calcination treatment is carried out at 350-450℃ for 3-8 hours; the amount of guar gum powder added is 1.5%-2.5% of the total mass of the system.

[0032] In some embodiments, the specific steps of the preparation method for the catalyst suitable for low-temperature methanol steam reforming to produce hydrogen are as follows: Copper nitrate, zinc sulfate, aluminum nitrate, ethylene glycol / ethanol, calcium oxide, and magnesium oxide are weighed and added to deionized water. The mixture is heated until copper nitrate, zinc sulfate, and aluminum nitrate completely dissolve in the deionized water, resulting in a mixed solution. Simultaneously, a saturated solution of oxalic acid with a theoretical value of 1.05-1.2N is prepared at 80-90℃. The saturated oxalic acid solution is added dropwise to the above mixed solution, dissolving calcium oxide and magnesium oxide. A reflux reaction is then carried out until the solution exhibits a uniform color. The solution is evaporated and concentrated to a sol-gel state. Guaranteed sesame powder is added and stirred to disperse and reduce viscosity, inhibiting the viscous sol-gel from adhering to the walls. The mixture is then dried and calcined to obtain the methanol reforming to produce hydrogen catalyst powder, labeled CuZnAl-RJ. The theoretical value of 1.05-1.2N represents that the actual amount of oxalic acid added is 1.05-1.2 times the theoretical value for the complete reaction of copper, zinc, and aluminum ions with oxalic acid. The theoretical value for the complete reaction of copper and zinc with oxalic acid is 1, and for aluminum it is 1.5.

[0033] The catalyst for methanol reforming to produce hydrogen in this invention consists of alumina, zinc oxide, copper oxide, and a small amount of auxiliary oxides. The auxiliary elements include calcium and magnesium. The catalyst composition directly affects the performance of methanol-to-hydrogen conversion. Preferably, by weight, the catalyst comprises 5-15 parts alumina, 8-20 parts zinc oxide, 65-85 parts copper oxide, and 0.01-5 parts metal oxide auxiliary agents.

[0034] Example 1 The steps for preparing the methanol steam reforming hydrogen production catalyst using the oxalic acid sol-gel method in this embodiment are as follows: According to the molar ratio Cu:Zn:Al:Ca,Mg=1:0.24:0.18:0.02:0.005, the raw materials copper nitrate, zinc sulfate, aluminum nitrate, calcium oxide, and magnesium oxide were added to 1000ml of deionized water, and 20ml of ethylene glycol / ethanol (1:1) was added. The temperature was raised to 80℃ to completely dissolve the copper nitrate, zinc sulfate, and aluminum nitrate.

[0035] Simultaneously, a saturated solution of oxalic acid with a theoretical value of 1.1N was prepared at 85℃. The saturated oxalic acid solution was then added dropwise to the above solution to completely dissolve calcium oxide and magnesium oxide. The mixture was refluxed for 8 hours until the solution showed a uniform color. The solution was then evaporated and concentrated to a sol-gel state. 2% of the total mass of guar gum powder was added, and the mixture was stirred and dispersed to reduce viscosity. After drying at 120℃ and calcining at 400℃ for 6 hours, methanol reforming hydrogen production catalyst powder was obtained, labeled as CuZnAl-RJ.

[0036] In this embodiment, the catalyst powder finally prepared by the oxalic acid sol-gel method has a composition of copper, zinc and aluminum of Cu:Zn:Al = 0.478:0.1:0.0923.

[0037] Example 2 In this embodiment, the catalyst is modified by changing the feed ratio so that the composition of the main elements copper, zinc and aluminum in the catalyst is Cu:Zn:Al=0.804:0.1:0.129.

[0038] The remaining steps and parameters are basically the same as in Example 1.

[0039] Comparative Example 1 The difference between this comparative example and Example 1 is that guar gum powder is not added during the catalyst preparation process in this comparative example, which forms a very viscous sol-gel that adheres to the reactor wall, leading to a decrease in catalyst yield. The remaining steps and parameters are basically the same as in Example 1.

[0040] Comparative Example 2 The difference between this comparative example and Example 1 is that guar gum powder was replaced with hydroxyethyl cellulose in the catalyst preparation process of this comparative example. The remaining steps and parameters are basically the same as in Example 1.

[0041] Test methods The catalysts prepared in the examples and comparative examples were subjected to the following tests: 1. Catalyst activity evaluation 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: X CH3OH (%) = [F R ×(C CO +C CO2 )×(32+18w)×f]×100%÷[F×ρmix×22.4×1000] Hydrogen generation rate per unit volume of catalyst: Y H2 =(F R ×C H2 ) ÷ (60 × V cat ) Correction factor: f = (T1 × P2) ÷ (T2 × P1) Among them, 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 ), C CO C CO2 C H2 These 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.

[0042] 2. Characterization methods for catalysts 1) SEM characterization tests can be used to observe the morphological characteristics and particle size of samples. Scanning electron microscopy (SEM) was performed on a Thermal Apero (USA) equipped with an ETD micro-scanning probe, with an accelerating voltage of 1-30kV and a working distance of 3-10mm, connected to an energy dispersive spectroscopy detector (EDS, EDAX, USA).

[0043] 2) Specific surface area was determined using a Micromeritics ASAP 2460 automated adsorption analyzer. Before N2 physisorption, the sample was degassed at 210℃ for 4 h. Specific surface area was calculated using the Brunauer-Emmett-Teller (BET) method. Micropore volume was calculated using the t-plot method, and pore size distribution was calculated using the Horvath+SaitoFoley method. Mesopore volume and corresponding pore size distribution were calculated using the Barrett-Joyner-Halenda (BJH) method.

[0044] 3) The particle size distribution was tested using a Mastersizer 3000 laser particle size analyzer, with water as the dispersion medium.

[0045] Test Results 1) Table 2 shows the performance data of CuZnAl-RJ catalysts with different compositions. The copper-zinc-aluminum oxide prepared by the oxalic acid gel method in Example 1 has an elemental composition of Cu:Zn:Al = 0.478:0.1:0.0923. At 230℃, the methanol conversion rate is 99.22%, the CO conversion rate is 6.53%, and the hydrogen generation rate per unit volume of catalyst is 1074.34 m³ / s. 3 / (m 3 *h).

[0046] Based on Example 1, the proportion of added raw materials was changed, altering the catalyst composition to Cu:Zn:Al = 0.804:0.1:0.129, i.e., Example 2. The catalyst of Example 2 exhibited a methanol conversion rate of 100% and a CO conversion rate of 6.32% at 230°C, with a hydrogen generation rate of 1121.22 m³ / s per unit volume of catalyst. 3 / (m 3 *h).

[0047] Table 2 Performance data of CuZnAl-RJ catalysts with different compositions Meanwhile, the catalyst performance test results for Comparative Example 1 showed that the methanol conversion rate at 230℃ was 84.1%, and the hydrogen production was 903m³. 3 / (m 3 *h). Catalyst performance test results for Comparative Example 2: Methanol conversion rate at 230℃ was 75.8%, and hydrogen production was 814.5m³. 3 / (m 3 *h), the performance is significantly lower than that of the example.

[0048] 2) Figure 1 The image shows the microstructure of the CuZnAl-RJ catalyst in Example 1. It is a strip-shaped structure composed of stacked nanoparticle catalysts with abundant pores.

[0049] 3) EDS-mapping results showed that copper, aluminum, and zinc elements were evenly distributed, with no single oxide precipitation or aggregation observed. Figure 2 As shown, it can be demonstrated that the copper, zinc and aluminum elements in the catalyst of Example 1 are uniformly dispersed and do not aggregate. Figure 2 This represents the distribution of elements.

[0050] 4) Figure 3 The nitrogen isotherm adsorption-desorption curves of the CuZnAl-RJ catalyst in Example 1 show typical type II isotherms of nonporous or macroporous materials.

[0051] 5) The particle size analysis results (number distribution) of the catalyst in Example 1 show that D 90 It is 2.24 micrometers, D 50 It is 1.26 micrometers, D 10 The particle size is 0.906 micrometers. The catalyst prepared by the method in Example 1 of the specification has a more uniform distribution of components and a particle size concentrated between 0.9 and 2.3 micrometers.

[0052] Based on the above description and experimental data, the preparation method of the catalyst for low-temperature methanol steam reforming to produce hydrogen of the present invention has the following advantages: (1) Breakthrough in low-temperature and high-efficiency catalytic performance: The catalyst prepared by the oxalic acid sol-gel method of this invention achieves a methanol conversion rate of 99.22% and a CO conversion rate of 6.53% at 230℃, with a hydrogen generation rate of 1074.34 m³ / s per unit volume of catalyst. 3 / (m 3 *h)‎, significantly superior to traditional CuZnAlOx catalysts (requiring 250~350℃).

[0053] (2) The oxalic acid sol-gel method of the present invention is an innovative "one-step direct synthesis method", which eliminates the solid-liquid separation and washing steps, shortens the preparation cycle, and achieves 100% methanol conversion rate after copper content optimization.

[0054] Existing technologies, such as patent CN102688759A, describe a catalyst for methanol reforming to produce hydrogen, its preparation method, and its application. This patent involves simultaneously adding Cu, Zn, and Al precursors and solid oxalic acid to an aqueous solution. The molar amount of oxalic acid added is 1.2-1.6 times the total molar amount of Cu, Zn, and Al. The reaction is carried out under stirring at a temperature of 50℃-90℃ for 5-9 hours. After the reaction, the catalyst is separated, dried at 100℃-120℃ for 10-15 hours, and calcined at 350℃-550℃ in an air or nitrogen atmosphere for 3-8 hours. After calcination, graphite is added and the catalyst is sheeted to obtain the finished catalyst. This patent uses oxalic acid as a precipitant, which avoids the influence of alkali metal impurities on catalyst performance. However, it is still a traditional precipitation method, where the catalyst is obtained through precipitation separation. The resulting catalyst particles are relatively large, and the distribution of components is not uniform. As can be seen from the data, the catalytic effect is not good, with a maximum methanol conversion rate of only 90.2% at 250℃. Secondly, the solid-liquid separation of precipitation increases the preparation cycle. Furthermore, the product formed by the oxalic acid precipitation method is relatively viscous. While small-scale laboratory synthesis can obtain the precipitate through centrifugation, it is difficult to achieve on a large scale. The method in this application uses reflux to form a sol-gel. The catalyst prepared by the sol-gel method has a smaller particle size and a more uniform distribution of catalyst components, concentrated between 0.9 and 2.3 micrometers. Moreover, the process is more suitable for large-scale mass production.

[0055] The above embodiments prepared by the method of the present invention are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing an oxalic acid sol-gel catalyst suitable for methanol steam reforming to produce hydrogen via the oxalic acid sol-gel method, characterized in that, Includes the following steps: Soluble copper, aluminum, and zinc sources, along with dispersants and metal oxide additives, are added to deionized water and heated to completely dissolve the soluble copper, aluminum, and zinc sources, resulting in a mixed solution. Prepare a saturated oxalic acid solution; The saturated oxalic acid solution was mixed with the mixed solution, and the metal oxide additive was completely dissolved. When the solution showed a uniform color, it was evaporated and concentrated to a sol-gel state. Guava powder was added to reduce viscosity, and after drying, it was calcined to obtain the catalyst.

2. The preparation method according to claim 1, characterized in that, The copper source, zinc source, aluminum source, and metal oxide additives are fed in a molar ratio of 1:0.15~0.35:0.1~0.3:0.01~0.

05.

3. The preparation method according to claim 1, characterized in that, The soluble copper source includes copper nitrate; the soluble aluminum source includes aluminum nitrate; the soluble zinc source includes zinc sulfate; the dispersant includes ethylene glycol and / or ethanol; and the auxiliary metal oxide includes oxides containing calcium and / or magnesium.

4. The preparation method according to claim 3, characterized in that, The dispersant comprises ethylene glycol and ethanol; the mass ratio of ethylene glycol to ethanol is 1:0.8-1.

2.

5. The preparation method according to claim 1, characterized in that, The heating refers to raising the temperature of the mixed solution system to 80-90℃.

6. The preparation method according to claim 1, characterized in that, The preparation of a saturated oxalic acid solution is carried out at 80-90℃.

7. The preparation method according to claim 1, characterized in that, The oxalic acid content in the saturated oxalic acid solution is 1.05-1.2 times the theoretical value for the complete reaction of copper, zinc, and aluminum ions with oxalic acid.

8. The preparation method according to claim 1, characterized in that, The reaction was carried out under reflux for 8-10 hours.

9. The preparation method according to claim 1, characterized in that, The amount of guar gum powder added is 1.5%-2.5% of the total mass of the system.

10. The preparation method according to claim 1, characterized in that, The drying process is carried out at 120-150℃.

11. The preparation method according to claim 1, characterized in that, The roasting process is performed at 350-450℃ for 3-8 hours.

12. A catalyst suitable for methanol steam reforming to produce hydrogen, characterized in that, It was prepared using the oxalic acid sol-gel method as described in any one of claims 1-10.

13. The catalyst according to claim 12, characterized in that, The catalyst includes alumina, zinc oxide, copper oxide, and metal oxide additives.

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