A method for preparing a copper-based catalyst supported on ZnAl2O4 and its application in catalytic methanol reforming for hydrogen production.
By loading a copper-based catalyst onto ZnAl2O4 spinel and using a two-site organic molecule promoter, the problems of high cost and high CO concentration of existing catalysts were solved, realizing a low-temperature and efficient methanol reforming hydrogen production reaction with high hydrogen yield and low CO selectivity.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SOUTHERN UNIVERSITY OF SCIENCE AND TECHNOLOGY
- Filing Date
- 2026-03-31
- Publication Date
- 2026-06-30
Smart Images
Figure CN122298430A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalysis technology, specifically the preparation and application of a catalyst for methanol reforming to produce hydrogen. Background Technology
[0002] Methanol is a widely available bulk raw material with advantages such as high energy density and convenient storage and transportation, and is considered a high-energy fuel suitable for industrial use. Catalytic conversion of methanol to hydrogen can meet the on-site hydrogen needs in many situations, solving the problems of hydrogen transportation and storage difficulties.
[0003] Methanol reforming for hydrogen production includes four methods: methanol cracking, methanol steam reforming, methanol partial oxidation, and methanol partial oxidation steam reforming. Methanol steam reforming has the highest hydrogen content. The core of the methanol reforming hydrogen production reaction is the catalyst, with copper-based catalysts and noble metal catalysts being the most studied. Noble metal catalysts result in high carbon monoxide (CO) concentrations. CO, as a byproduct of methanol reforming for hydrogen production, can poison and deactivate noble metal catalysts even in small amounts during subsequent hydrogen fuel cell utilization. Copper-based catalysts, as non-noble metal catalysts, have attracted considerable attention. Chinese invention patent CN101112684A discloses a catalyst for methanol reforming for hydrogen production. This catalyst uses La, Ce, Pr, Gd, and Sm as A-sites and Cr, Zr, Zn, Ni, Co, or Mn as B-sites to synthesize an ABO3 perovskite catalyst. This catalyst exhibits high conversion rates in the high-temperature autothermal methanol reforming hydrogen production reaction at 460–540℃. However, the catalyst has high preparation costs, and the catalytic reaction temperature needs to be lowered. A 1%Pd–20%Cu / ZnAl2O4 catalyst has been reported (Applied Catalysis A: General 2014, 26-34). The addition of precious metals gives the catalyst high activity for methanol-to-hydrogen conversion at 240℃, but it also increases the cost. The existing problems with methanol reforming catalysts for hydrogen production are that precious metal catalysts have high activity but also high cost; copper-based catalysts have high loading and low dispersion, but due to the low Taman temperature of copper, particle aggregation occurs after activation, leading to higher reaction temperatures and high CO concentration in the hydrogen-rich product gas.
[0004] To address the aforementioned problems, it is necessary to develop methanol reforming catalysts with high catalytic activity and good catalytic stability. This invention proposes a method for preparing a copper-based catalyst supported on ZnAl₂O₄ spinel and its application in catalytic methanol reforming for hydrogen production. Summary of the Invention
[0005] The present invention aims to provide a method for preparing a highly efficient catalyst for methanol reforming to produce hydrogen. This catalyst uses spinel-structured ZnAl2O4 as a support, and the formation of the copper-based catalyst is controlled by adding a two-site organic molecular promoter. This achieves highly uniform dispersion of the copper active component, strengthens the interaction between the active metal and the support, effectively reduces the size of copper particles, inhibits aggregation, provides more active sites, and improves the performance of the methanol reforming to produce hydrogen reaction.
[0006] To achieve the above objectives, the present invention adopts the following technical methods:
[0007] A method for preparing a ZnAl2O4-supported copper-based catalyst and its application in catalytic methanol reforming for hydrogen production, characterized by the following preparation process:
[0008] Copper metal salt was dissolved in water, and a certain amount of organic molecular auxiliaries were added. The mixture was stirred at room temperature for 0.5 hours until homogeneous. ZnAl2O4 support was added, and the mixture was stirred at room temperature for another 0.5 hours. Then, the temperature was raised to 80°C and stirred for 1 hour. The mixture was transferred to an oven and dried at 80°C. The resulting solid product was ground evenly and then calcined at high temperature in an atmosphere to obtain a ZnAl2O4-supported copper-based catalyst.
[0009] The above preparation method has the following characteristics:
[0010] The copper metal salt is at least one of copper nitrate, acetate, and chloride.
[0011] The copper metal salt is dissolved in water and can be mixed with other metal salts, including one or more of lanthanum and cerium metal salts, to form a metal-doped copper-based catalyst.
[0012] The ZnAl2O4 supported copper-based catalyst has a copper loading of 10-50 wt%.
[0013] The organic molecular auxiliaries are at least one of bisamino and bissulfhydryl organic molecules; the bisamino organic auxiliaries are at least one of ethylenediamine, propylenediamine, and hexamethylenediamine; the bissulfhydryl organic auxiliaries are at least one of ethylenedithiol, propylenedithiol, and hexamethylenedithiol.
[0014] The amount of the organic molecular auxiliary agent used is such that the molar ratio of the organic molecule to copper is 1:1-10:1.
[0015] The atmosphere is either air or oxygen, the high-temperature calcination temperature is 350-550℃, and the calcination time is 3-5 hours.
[0016] The aforementioned organic molecule dual-site binding assistance refers to the ability of the diamino or dithiol groups of organic molecules to bind to the support ZnAl2O4 and copper ions respectively through dual sites, acting as a bridge to anchor copper ions on the spinel support, so that copper is evenly distributed on the support, effectively reducing the size of copper particles (4-30 nm), inhibiting aggregation, and providing more active sites for the catalyst.
[0017] The ZnAl2O4-supported copper-based catalyst described above is used for methanol reforming to produce hydrogen. The catalyst is packed into a fixed-bed reactor for in-situ reduction under a 50% H2 / N2 mixture at 330°C. After 1 hour of reduction, methanol vapor reforming to produce hydrogen is carried out at atmospheric pressure at 220-300°C, an oxygen-to-methanol-to-water ratio of 0.4 / 1 / 1.2, and a methanol mass hourly space velocity (MHSV) of 1.0-6.0 h⁻¹. -1 .
[0018] The ZnAl2O4-supported copper-based catalyst described above exhibits excellent catalytic activity with high methanol conversion and hydrogen yield, and low CO selectivity in the methanol autothermal reforming hydrogen production reaction.
[0019] Compared with the prior art, the present invention has the following beneficial effects:
[0020] This invention uses ZnAl₂O₄ as a support and employs a two-site organic molecule-assisted loading of a copper-based catalyst to achieve the formation and high dispersion of nanoscale copper particles. This enhances the interaction between the active metal and the support, ensuring stable immobilization of the copper active component and endowing the ZnAl₂O₄-supported copper-based catalyst with excellent catalytic activity and stability. The catalyst exhibits good catalytic performance in the low-temperature catalytic reaction of methanol reforming to hydrogen, with high hydrogen yield and low CO selectivity. The method of this invention is simple, easy to operate, and highly controllable. The performance of the ZnAl₂O₄-supported copper-based catalyst in the catalytic reaction of methanol reforming to hydrogen is significantly better than that of catalysts prepared by other traditional methods. Attached Figure Description
[0021] Figure 1 The images shown are scanning electron microscope (SEM) images and elemental surface scan mapping images of the catalyst prepared in Example 4 of this invention.
[0022] Figure 2 XRD diffraction patterns of the catalysts prepared on the spinel-structured ZnAl2O4 support, in Example 4, and in Comparative Example 1;
[0023] Figure 3 A comparison of the catalytic performance of the catalysts prepared in Example 4 and Comparative Example 1 for methanol reforming to hydrogen production: (a) methanol conversion; (b) CO selectivity; (c) hydrogen yield. Example 4; Comparative Example 1). Detailed Implementation
[0024] The present invention will now be described with reference to specific embodiments. Experimental methods not specifically described in the embodiments generally use conventional conditions, conditions described in manuals, or conditions recommended by the manufacturer. The general equipment, materials, reagents, etc., used are all commercially available unless otherwise specified. The raw materials used in the following embodiments and comparative examples are all commercially available.
[0025] Example 1:
[0026] Propylene dithiol was used as an organic molecule auxiliary agent to synthesize the catalyst. 1.77 g of copper nitrate was dissolved in 5 mL of deionized water, 0.25 mL of propylene dithiol was added, and the pH was adjusted to 11 with ammonia. 2.00 g of ZnAl2O4 support was added, and the mixture was stirred at room temperature for 0.5 h. The temperature was then raised to 80 °C and stirred for another 1 h. The resulting mixture was transferred to an oven and dried at 80 °C for 12 h. The dried solid powder was crushed evenly and then calcined at 450 °C in an oxygen atmosphere for 4 h to obtain the Cu / ZnAl2O4-1 catalyst.
[0027] Example 2:
[0028] Hexamethylenediamine was used as an organic molecule auxiliary agent to synthesize the catalyst. 1.77 g of copper nitrate was dissolved in 5 mL of deionized water, 2.525 mL of hexamethylenediamine was added, followed by 2.00 g of ZnAl2O4 support. The mixture was stirred at room temperature for 0.5 h, then heated to 80 °C and stirred for another 1 h. The resulting mixture was transferred to an oven and dried at 80 °C for 12 h. After the dried solid powder was crushed evenly, it was calcined at 450 °C in air for 4 h to obtain the Cu / ZnAl2O4-2 catalyst.
[0029] Example 3:
[0030] Propylene diamine was used as an organic molecule auxiliary agent to synthesize the catalyst. 1.77 g of copper nitrate was dissolved in 5 mL of deionized water, 2.525 mL of propylene diamine was added, followed by 2.00 g of ZnAl2O4 support. The mixture was stirred at room temperature for 0.5 h, then heated to 80 °C and stirred for another 1 h. The resulting mixture was transferred to an oven and dried at 80 °C for 12 h. The dried solid powder was then crushed evenly and calcined at 450 °C in air for 4 h to obtain the Cu / ZnAl2O4-3 catalyst.
[0031] Example 4:
[0032] Ethylenediamine was used as an organic molecule auxiliary agent to synthesize the catalyst. 1.77 g of copper nitrate was dissolved in 5 mL of deionized water, and 2.525 mL of ethylenediamine was added, resulting in a molar ratio of ethylenediamine to copper of 4:1. 2 g of ZnAl₂O₄ support was weighed, stirred at room temperature for 0.5 h, then heated to 80 °C and stirred for another 1 h. The mixture was then transferred to a drying oven and dried at 80 °C for 12 h. The dried solid powder was then crushed evenly and calcined in air at 450 °C for 4 h to obtain the Cu / ZnAl₂O₄⁻ catalyst.
[0033] Example 5:
[0034] Ethylenediamine was used as an organic molecular auxiliary agent to synthesize the catalyst, and the molar ratio of ethylenediamine to copper was controlled to be 1:1. 1.77 g of copper nitrate was dissolved in 5 mL of deionized water, and 0.63 mL of ethylenediamine was added, at which point the molar ratio of ethylenediamine to copper was 1:1. 2 g of ZnAl₂O₄ support was weighed, stirred at room temperature for 0.5 h, then heated to 80 °C and stirred for another 1 h. The mixture was then transferred to a drying oven and dried at 80 °C for 12 h. The dried solid powder was then crushed evenly and calcined in air at 450 °C for 4 h to obtain the Cu / ZnAl₂O₄⁻⁵ catalyst.
[0035] Example 6:
[0036] Ethylenediamine was used as an organic molecular auxiliary agent to synthesize the catalyst, and the molar ratio of ethylenediamine to copper was controlled to be 10:1. 1.77 g of copper nitrate was dissolved in 5 mL of deionized water, and 25.25 mL of ethylenediamine was added, resulting in a molar ratio of ethylenediamine to copper of 10:1. 2 g of ZnAl₂O₄ support was weighed, stirred at room temperature for 0.5 h, then heated to 80 °C and stirred for another 1 h. The mixture was then transferred to a drying oven and dried at 80 °C for 12 h. The dried solid powder was then crushed evenly and calcined in air at 450 °C for 4 h to obtain the Cu / ZnAl₂O₄-6 catalyst.
[0037] Example 7:
[0038] The calcination temperature was controlled at 350℃. 1.77 g of copper nitrate was dissolved in 5 mL of deionized water, and 2.525 mL of ethylenediamine was added. 2 g of ZnAl₂O₄ support was weighed, stirred at room temperature for 0.5 h, then heated to 80℃ and stirred for another 1 h. The mixture was then transferred to a drying oven and dried at 80℃ for 12 h. The dried solid powder was crushed evenly and calcined in air at 350℃ for 4 h to obtain the Cu / ZnAl₂O₄-7 catalyst.
[0039] Example 8:
[0040] The calcination temperature was controlled at 550℃. 1.77 g of copper nitrate was dissolved in 5 mL of deionized water, and 2.525 mL of ethylenediamine was added. 2 g of ZnAl₂O₄ support was weighed, stirred at room temperature for 0.5 h, then heated to 80℃ and stirred for another 1 h. The mixture was then transferred to a drying oven and dried at 80℃ for 12 h. The dried solid powder was crushed evenly and calcined in air at 550℃ for 4 h to obtain the Cu / ZnAl₂O₄-8 catalyst.
[0041] Example 9:
[0042] The calcination time was adjusted to 3 hours. 1.77 g of copper nitrate was dissolved in 5 mL of deionized water, and 2.525 mL of ethylenediamine was added. 2 g of ZnAl₂O₄ support was weighed, stirred at room temperature for 0.5 hours, then heated to 80°C and stirred for another 1 hour. The mixture was then transferred to a drying oven and dried at 80°C for 12 hours. The dried solid powder was then crushed evenly and calcined in air at 450°C for 3 hours to obtain the Cu / ZnAl₂O₄-9 catalyst.
[0043] Example 10:
[0044] The calcination time was adjusted to 5 hours. 1.77 g of copper nitrate was dissolved in 5 mL of deionized water, and 2.525 mL of ethylenediamine was added. 2 g of ZnAl₂O₄ support was weighed, stirred at room temperature for 0.5 hours, then heated to 80°C and stirred for another 1 hour. The mixture was then transferred to a drying oven and dried at 80°C for 12 hours. The dried solid powder was then crushed evenly and calcined in air at 450°C for 5 hours to obtain the Cu / ZnAl₂O₄-10 catalyst.
[0045] Example 11:
[0046] Lanthanum nitrate was used as an additional additive. 1.77 g of copper nitrate and 0.234 g of lanthanum nitrate (La(NO3)3·xH2O) were dissolved in 5 mL of deionized water, and 2.525 mL of ethylenediamine was added. 2 g of ZnAl2O4 support was weighed, stirred at room temperature for 0.5 h, then heated to 80 °C and stirred for another 1 h. The mixture was then transferred to a drying oven and dried at 80 °C for 12 h. The dried solid powder was crushed evenly and calcined in air at 450 °C for 4 h to obtain a Cu / ZnAl2O4-11 catalyst with a La loading of 5 wt%.
[0047] Example 12:
[0048] Cerium nitrate was added as an auxiliary agent. 1.77 g of copper nitrate and 0.31 g of cerium nitrate (Ce(NO3)3) were dissolved in 5 mL of deionized water, and 2.525 mL of ethylenediamine was added. 2 g of ZnAl2O4 support was weighed, stirred at room temperature for 0.5 h, then heated to 80 °C and stirred for another 1 h. The mixture was then transferred to a drying oven and dried at 80 °C for 12 h. The dried solid powder was crushed evenly and calcined in air at 450 °C for 4 h to obtain a Cu / ZnAl2O4-12 catalyst with a Ce loading of 5 wt%.
[0049] Example 13:
[0050] The loading of copper nitrate was adjusted to 10 wt%. 0.59 g of copper nitrate was dissolved in 5 mL of deionized water, and 0.840 mL of ethylenediamine was added. 2 g of ZnAl₂O₄ support was weighed, stirred at room temperature for 0.5 h, then heated to 80 °C and stirred for another 1 h. The mixture was then transferred to a drying oven and dried at 80 °C for 12 h. The dried solid powder was crushed evenly and calcined in air at 450 °C for 4 h to obtain the Cu / ZnAl₂O₄-13 catalyst.
[0051] Example 14:
[0052] The loading of copper nitrate was adjusted to 50 wt%. 2.95 g of copper nitrate was dissolved in 5 mL of deionized water, and 4.200 mL of ethylenediamine was added. 2 g of ZnAl₂O₄ support was weighed, stirred at room temperature for 0.5 h, then heated to 80 °C and stirred for another 1 h. The mixture was then transferred to a drying oven and dried at 80 °C for 12 h. The dried solid powder was then crushed evenly and calcined in air at 450 °C for 4 h to obtain the Cu / ZnAl₂O₄-14 catalyst.
[0053] Example 15:
[0054] Copper acetate was used as the copper metal salt. 1.88 g of copper acetate was dissolved in 5 mL of deionized water, and 2.525 mL of ethylenediamine was added. 2 g of ZnAl₂O₄ support was weighed, stirred at room temperature for 0.5 h, then heated to 80 °C and stirred for another 1 h. The mixture was then transferred to a drying oven and dried at 80 °C for 12 h. The dried solid powder was then crushed evenly and calcined in air at 450 °C for 4 h to obtain the Cu / ZnAl₂O₄-15 catalyst.
[0055] Comparative Example 1:
[0056] To compare the catalytic performance of samples modified with organic additives, ZnAl2O4 was still used as the support, and copper salt was impregnated onto the ZnAl2O4 support using the traditional impregnation method. 1.77 g of copper nitrate was dissolved in 5 mL of deionized water, and 2 g of ZnAl2O4 support was added to the solution. The mixture was stirred at room temperature for 0.5 h, then heated to 80 °C and stirred for another 1 h. The mixture was then transferred to a drying oven and dried at 80 °C for 12 h. The dried solid powder was then crushed evenly and calcined in air at 450 °C for 4 h to obtain the Cu / ZnAl2O4-16 catalyst.
[0057] Comparative Example 2:
[0058] Preparation of spinel-structured ZnAl2O4 support. 11.9 g of zinc nitrate (Zn(NO3)2·6H2O) and 30 g of aluminum nitrate (Al(NO3)3·9H2O) were weighed and dissolved in 60 mL of deionized water to form a homogeneous solution. Ammonia was added to maintain the pH of the solution at 11. The mixture was stirred and aged for 1 h. The resulting mixture was filtered and washed with deionized water until neutral to obtain a white colloidal zinc aluminate hydrate precursor. After drying, the precursor was crushed and passed through a 60-mesh sieve. It was then calcined in a muffle furnace at 550 °C for 4 h to obtain the ZnAl2O4 support.
[0059] Example 16:
[0060] Performance evaluation of the catalyst in the methanol reforming hydrogen production reaction. The methanol reforming hydrogen production reaction was carried out in a fixed bed at atmospheric pressure. Before use, the solid catalyst powder was crushed into tablets, and 0.1 g of 40-60 mesh catalyst was sieved and loaded into the fixed bed for in-situ reduction. The reduction temperature was 330℃, the reduction time was 1 h, and the reducing atmosphere was a 50% H2 / N2 mixture. At a reaction temperature of 220-300℃, the oxygen-methanol-water ratio in the feed was 0.4:1:1.2 (mol / mol / mol), and the methanol mass hourly space velocity was 3.19 h⁻¹. -1 Nitrogen gas was used as both the carrier gas and the internal standard gas during the reaction.
[0061] The catalytic performance of the examples and comparative examples was tested and compared at a catalytic reaction temperature of 280℃. The results are shown in Table 1, including the conversion rate of methanol, the selectivity of carbon monoxide (CO), and the yield of hydrogen (H2).
[0062] Table 1. Comparison of catalytic performance of catalysts prepared by the method of the present invention and those prepared by the traditional impregnation method for methanol reforming to hydrogen production.
[0063] As shown in Table 1, the Cu / ZnAl2O4 catalyst prepared by the present invention using the dual-site binding assistance of organic molecules exhibits significantly superior catalytic performance in the methanol reforming hydrogen production reaction, demonstrating lower CO selectivity, higher methanol conversion rate, and higher hydrogen yield. In the reaction of the catalyst obtained in Example 4, the methanol conversion rate was 94.04%, and the CO selectivity was 0.94%; while the methanol conversion rate of the catalyst synthesized by the conventional impregnation method was 60.38%, and the CO selectivity was 2.21%.
[0064] The above embodiments describe the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention and are not intended to limit the scope of the invention in any way. Various changes and modifications can be made to the invention without departing from its scope, and all such changes and modifications fall within the scope of the claims.
Claims
1. A ZnAl2O4 supported copper-based catalyst, characterized in that, Using spinel-structured ZnAl2O4 as a support and copper as an active component, the copper is loaded onto the ZnAl2O4 support with the assistance of the two-site binding of organic molecules, and the loading amount of copper is 10-50 wt%.
2. The method for preparing a ZnAl2O4-supported copper-based catalyst according to claim 1, characterized in that, The copper is derived from at least one of copper nitrate, acetate, and chloride.
3. The ZnAl2O4 supported copper-based catalyst according to claim 1, characterized in that, It also includes a doped metal component, which is one or more of lanthanum and cerium, and the doped metal component is derived from its corresponding metal salt.
4. A method for preparing the ZnAl2O4-supported copper-based catalyst according to any one of claims 1-3, characterized in that, Includes the following steps: Copper metal salt was dissolved in water, and an organic molecular auxiliary agent was added. The copper ions were anchored on the support surface by the two-site binding assistance of the organic molecules. After stirring at room temperature until the mixture was homogeneous, a spinel-structured ZnAl2O4 support was added, and stirring was continued at room temperature. Then, the mixture was heated and stirred. The resulting mixture was dried, and the dried solid product was ground evenly and then calcined at high temperature under a specific atmosphere to obtain the ZnAl2O4 supported copper-based catalyst.
5. The preparation method according to claim 4, characterized in that, The organic molecular auxiliary agent is at least one of organic molecules containing diamino and disulfide groups; wherein, the diamino organic auxiliary agent is at least one of ethylenediamine, propylenediamine, and hexamethylenediamine; and the disulfide organic auxiliary agent is at least one of ethylenedithiol, propylenedithiol, and hexamethylenedithiol.
6. The preparation method according to claim 4, characterized in that, The amount of the organic molecular auxiliary agent is such that the molar ratio of organic molecules to copper is 1:1-10:
1.
7. The preparation method according to claim 4, characterized in that, The specific atmosphere is either an air atmosphere or an oxygen atmosphere; the high-temperature calcination temperature is 350-550℃, and the calcination time is 3-5h.
8. The preparation method according to claim 4, characterized in that, The aforementioned organic molecule dual-site binding assistance refers to the ability of the diamino or dithiol groups of organic molecules to bind with the carrier ZnAl2O4 and copper ions respectively, acting as a bridge to anchor the copper ions on the spinel carrier, thereby ensuring a uniform distribution of copper on the carrier.
9. A method for preparing a ZnAl2O4-supported copper-based catalyst according to claim 1, characterized in that, The ZnAl2O4 supported copper-based catalyst is used for the methanol autothermal reforming hydrogen production reaction under the following conditions: atmospheric pressure and reaction temperature of 220-300℃.