Copper oxide catalyst, method for preparing the same, and use thereof

Abstract

The application provides a kind of nano copper oxide catalyst, by the temperature of 500-600 ℃ nano copper oxide particles in rare earth metal salt solution quenching, make rare earth metal oxide cover on the surface of nano copper oxide particles, simultaneously make rare earth metal ion into the copper oxide lattice on the surface of nano copper oxide particles, and make Cu 2+ In the copper oxide lattice be reduced to Cu + After the relative abundance of oxygen vacancy on the surface of nano copper oxide particles is improved and obtained.The application also provides a preparation method and application of the nano copper oxide catalyst.

Description

Technical Field

[0001] This invention belongs to the field of catalysts, specifically relating to a copper oxide catalyst. Background Technology

[0002] The increasing energy consumption and environmental pollution caused by the use of fossil fuels has prompted a global effort to develop eco-friendly renewable energy strategies. Hydrogen, as a next-generation energy source, has attracted growing research attention, but its high production and transportation costs severely limit its widespread application. Liquid methanol is considered a promising hydrogen carrier, possessing inherent advantages in terms of safety and transportation economics. Furthermore, CH3OH has advantages such as high volumetric energy density and renewability, enabling low-cost in-situ hydrogen utilization in fuel cell systems. Therefore, developing efficient methanol-to-hydrogen reactions is crucial for alleviating environmental problems and the energy crisis. Methanol steam reforming (MSR) is the most developed and commonly used method, primarily involving methanol decomposition and water-gas shift reactions, due to its advantages such as a high H / C molar ratio, zero sulfur and nitrogen emissions, and low reforming temperature (200-350℃).

[0003] Developing efficient and durable catalysts is of great significance for the MSR reaction. Copper-based catalysts have attracted increasing attention due to their advantages such as low cost, high activity, and H2 selectivity.

[0004] However, due to the low Taman temperature of copper (407°C), active copper is prone to agglomeration and sintering during the reaction, so improving the thermal stability of copper-based catalysts is also an important issue.

[0005] Typically, impregnation, sol-gel, and co-precipitation methods are used to prepare copper-based nanocatalysts for various thermocatalytic reactions. These methods can control the atomic-scale composition and morphology of the catalyst surface to a certain extent. However, many strategies involve rather complex preparation processes, such as harsh synthesis conditions (pressure, gas environment, etc.), specific solvents, and laborious modification treatments (annealing, ion exchange, or etching), all of which pose obstacles to large-scale applications. Therefore, it is essential to develop a simple, universal, and low-cost technique to achieve efficient surface engineering and improve the catalytic performance of MSR catalysts. Summary of the Invention

[0006] The first objective of this invention is to provide a highly catalytically active and highly selective nano-copper oxide catalyst.

[0007] A second objective of this invention is to provide a method for preparing the aforementioned nano-copper oxide catalyst.

[0008] A third objective of this invention is to provide the application of the aforementioned nano-copper oxide catalyst in the field of alcohol reforming for hydrogen production.

[0009] The present invention is achieved through the following technical solution.

[0010] A nano-copper oxide catalyst is prepared by quenching nano-copper oxide particles at 500-600℃ in a rare earth metal salt solution, causing the rare earth metals to oxidize and coat the surface of the nano-copper oxide particles. Simultaneously, rare earth metal ions enter the copper oxide lattice on the surface of the nano-copper oxide particles, and Cu in the copper oxide lattice... 2+ Reduced to Cu + It is obtained by increasing the relative abundance of oxygen vacancies on the surface of the nano-copper oxide particles.

[0011] The rare earth metal salt solution includes a Ce soluble salt solution, a La soluble salt solution, a Y soluble salt solution, a Nd soluble salt solution, or a Gd soluble salt solution.

[0012] The particle size of the nano-copper oxide particles is 20-50 nm.

[0013] The soluble salts of Ce include cerium nitrate, cerium chloride, or cerium sulfate;

[0014] The soluble salts of La include lanthanum nitrate, lanthanum chloride, or lanthanum sulfate;

[0015] The soluble salts of Y include yttrium nitrate, yttrium chloride, or yttrium sulfate;

[0016] The soluble salts of Nd include neodymium nitrate, neodymium chloride, or neodymium sulfate;

[0017] The soluble salts of Gd include gadolinium nitrate, gadolinium chloride, or gadolinium sulfate.

[0018] The relative abundance of oxygen vacancies on the surface of the nano-copper oxide catalyst is 45%-46%.

[0019] The concentration of the rare earth metal salt solution is 0.25-0.35M.

[0020] A method for preparing a nano-copper oxide catalyst includes the following steps:

[0021] The nano-copper oxide particles are heat-treated, then quenched in a rare earth metal salt solution, and the product is collected and dried to obtain the final product.

[0022] The mass-to-volume ratio of nano-copper oxide particles to rare earth metal salt solution is 1.3-1.6 g: 25 mL.

[0023] The heat treatment temperature is 500-600℃;

[0024] The heating rate of the heat treatment is 5-6℃ / min;

[0025] The heat treatment time is 2-3 hours.

[0026] The drying temperature is 60-70℃;

[0027] The drying time is 10-12 hours.

[0028] An application of the aforementioned nano-copper oxide catalyst is in the reforming of alcohols to produce hydrogen.

[0029] The alcohols include C1-C5 alcohols.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] The nano-copper oxide catalyst provided by this invention introduces cerium dioxide (CeO2) as a reforming promoter for alcohols through quenching. Quenching in a rare earth metal salt solution allows rare earth metal ions to enter the copper oxide lattice on the surface of the nano-copper oxide particles, thereby creating defects on the catalyst surface and introducing more oxygen vacancies. The presence of these oxygen vacancies accelerates the dissociation of H2O, thus promoting the MSR reaction and reducing the CO concentration. On the other hand, since the rare earth metal oxides loaded on the surface of the quenched nano-copper oxide particles act as a physical barrier, they effectively prevent the agglomeration and sintering of Cu species during the reaction, improving the thermal stability of the Cu-based catalyst.

[0032] The preparation method of the nano-copper oxide catalyst provided by this invention is simple, universal, and low in cost. It can achieve efficient surface engineering and improve the catalytic performance of the prepared nano-copper oxide catalyst.

[0033] The nano-copper oxide catalyst provided by this invention can be applied to the efficient and highly selective reforming of alcohols to produce hydrogen. Attached Figure Description

[0034] Figure 1 A schematic diagram of the MSR reaction is shown;

[0035] Figure 2a A schematic diagram of the quenching process for nano-copper oxide catalyst is shown.

[0036] Figure 2b The XRD patterns of CuO-R, Ce / CuO-R, and Ce / CuO-Q are shown.

[0037] Figure 2c Raman plots of CuO-R, Ce / CuO-R, and Ce / CuO-Q are shown.

[0038] Figure 2d A TEM image of Ce / CuO-Q is shown;

[0039] Figure 2e Ce / CuO-QHAADF-STEM image is shown;

[0040] Figure 2f Ce / CuO-QHAADF-STEM image is shown;

[0041] Figure 2g STEM-EDX images of Ce / CuO-Q are shown;

[0042] Figure 2h The STEM-EDX plot of Cu in Ce / CuO-Q is shown;

[0043] Figure 2i The distribution of O element in Ce / CuO-Q via STEM-EDX is shown;

[0044] Figure 2j The distribution of Ce element in Ce / CuO-Q via STEM-EDX is shown;

[0045] Figure 3 a shows enlarged views of the XRD patterns of CuO-R, Ce / CuO-R, and Ce / CuO-Q;

[0046] Figure 3 b shows enlarged views of the Raman plots for CuO-R, Ce / CuO-R, and Ce / CuO-Q;

[0047] Figure 4 shows SEM images of CuO-R, Ce / CuO-R, and Ce / CuO-Q; among them, Figure 4a SEM images of CuO-R are shown; Figure 4b SEM images of Ce / CuO-R are shown; Figure 4c SEM images of Ce / CuO-Q are shown;

[0048] Figure 5 a shows a TEM image of Ce / CuO-R;

[0049] Figure 5 b shows a STEM-EDX image of Ce / CuO-R;

[0050] Figure 5 c shows the Cu element distribution in Ce / CuO-R using STEM-EDX;

[0051] Figure 5 d shows the O element distribution in the STEM-EDX of Ce / CuO-R;

[0052] Figure 5 e shows the Ce element distribution in Ce / CuO-R using STEM-EDX;

[0053] Figure 6a shows the EPR spectra of CuO-R, Ce / CuO-R, and Ce / CuO-Q;

[0054] Figure 6 b shows the basis Figure 6 Quantitative results of the EPR signal intensity of CuO-R, Ce / CuO-R and Ce / CuO-Q on the concentration of oxygen vacancies in CuO-R, Ce / CuO-R and Ce / CuO-Q;

[0055] Figure 6 c shows the O1S diagrams of Ce / CuO-R and Ce / CuO-Q;

[0056] Figure 6 d shows the Cu2p plots for Ce / CuO-R and Ce / CuO-Q;

[0057] Figure 6 e shows the Cu LMM AES plots of Ce / CuO-R and Ce / CuO-Q;

[0058] Figure 6 f shows the Ce3d plots for Ce / CuO-R and Ce / CuO-Q;

[0059] Figure 7 Shown are (a) XRD patterns, (b) Cu 2p XPS spectra, and (c) Cu LMM AESspectra of the catalysts after 10 h of the reforming reaction.

[0060] Figure 8 The following are O 1s XPS plots of CuO-R, Ce / CuO-R, and Ce / CuO-Q after 10 hours of reforming reaction;

[0061] Figure 9 Figure a shows the conversion rates of methanol by CuO-R, Ce / CuO-R, and Ce / CuO-Q at different temperatures;

[0062] Figure 9 b shows the selectivity of CuO-R, Ce / CuO-R, and Ce / CuO-Q for CO at different temperatures;

[0063] Figure 9 Figure c shows the conversion rates of hydrogen to CuO-R, Ce / CuO-R, and Ce / CuO-Q at different temperatures;

[0064] Figure 9Figure d shows the catalytic effect of Ce / CuO-Q under steady state; the reaction conditions were 4 mL / h and the molar ratio of H2O to CH3OH was 1.05.

[0065] Figure 10 a shows the steady-state catalytic diagram of Ce / CuO-Q;

[0066] Figure 10 b shows the steady-state catalytic diagram of La / CuO-Q;

[0067] Figure 10 c shows the steady-state catalytic diagram of Y / CuO-Q;

[0068] Figure 10 Figure d shows the steady-state catalytic diagram of Nd / CuO-Q;

[0069] Figure 10 e shows the steady-state catalytic diagram of Gd / CuO-Q;

[0070] Figure 10 f shows the selectivity of the MSR reaction for CO for La / CuO-Q, Y / CuO-Q, Nd / CuO-Q and Gd / CuO-Q; the reaction conditions are 4 mL / h and the molar ratio of H2O to CH3OH is 1.05;

[0071] Figure 11 The following are FTIR spectra of Ce / CuO-Q after reforming at different times;

[0072] Figure 12 a shows the FE-SEM image of Ce / CuO-Q;

[0073] Figure 12 b shows the FE-SEM image of U-Ce / CuO-Q;

[0074] Figure 12 c shows the Raman plots of Ce / CuO-Q and U-Ce / CuO-Q. Detailed Implementation

[0075] The present invention will be further described below with reference to specific embodiments.

[0076] Example 1

[0077] CuO nanoparticles with a particle size of 100 nm were calcined at 550°C for 2 hours (heating rate: 5°C / min), with 1.5 g of copper oxide added. The calcined product was then immersed in 25 mL of Ce(NO3)3 (0.3 M) solution for quenching. After magnetic stirring for 5 minutes, the product was collected by multiple centrifugations and dried in a 60°C oven for 12 hours. The nano-copper oxide catalyst prepared in Example 1 is designated Ce / CuO-Q.

[0078] Comparative Example 1

[0079] 100 nm CuO nanoparticles were calcined at 550°C for 2 hours and then naturally cooled to room temperature. The CuO nanoparticles were then added to a Ce(NO3)3 solution, stirred, centrifuged, and finally dried. The catalyst prepared in Comparative Example 1 was labeled Ce / CuO-R.

[0080] Comparative Example 2

[0081] 100 nm CuO nanoparticles were calcined at 550°C for 2 hours and then naturally cooled to room temperature. The catalyst prepared in Comparative Example 2 was labeled CuO-R.

[0082] In this invention, the catalysts after 10 hours of MSR reaction are named R-CuO-R, R-Ce / CuO-R, and R-Ce / CuO-Q, respectively. The catalyst after 100 hours of reaction is labeled U-Ce / CuO-Q.

[0083] Inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis showed that the Ce content in Ce / CuO-Q and Ce / CuO-R was 1.24 wt.% and 1.31 wt.%, respectively.

[0084] Example 2

[0085] CuO nanoparticles with a particle size of 100 nm were calcined at 550°C for 2 hours (heating rate: 5°C / min), with 1.3 g of copper oxide added. The calcined product was then immersed in 25 mL of La(NO3)3 (0.3 M) solution for quenching. After magnetic stirring for 5 minutes, the product was collected by multiple centrifugations and dried in a 60°C oven for 12 hours. The nano-copper oxide catalyst prepared in Example 2 is designated as La / CuO-Q.

[0086] Example 3

[0087] CuO nanoparticles with a particle size of 100 nm were calcined at 550°C for 2 hours (heating rate: 5°C / min), with 1.6 g of copper oxide added. The nanoparticles were then immersed in 25 mL of Y(NO3)3 (0.3 M) solution for quenching. After magnetic stirring for 5 minutes, the product was collected by multiple centrifugations and dried in a 60°C oven for 12 hours. The nano-copper oxide catalyst prepared in Example 3 is designated as Y / CuO-Q.

[0088] Example 4

[0089] CuO nanoparticles with a particle size of 100 nm were calcined at 550°C for 2 hours (heating rate: 5°C / min), with 1.5 g of copper oxide added. The nanoparticles were then immersed in 25 mL of Nd(NO3)3 (0.3 M) solution for quenching. After magnetic stirring for 5 minutes, the product was collected by multiple centrifugations and dried in a 60°C oven for 12 hours. The nano-copper oxide catalyst prepared in Example 4 is designated as Nd / CuO-Q.

[0090] Example 5

[0091] CuO nanoparticles with a particle size of 100 nm were calcined at 550°C for 2 hours (heating rate: 5°C / min), with 1.5 g of copper oxide added. The nanoparticles were then immersed in 25 mL of Gd(NO3)3 (0.3 M) solution for quenching. After magnetic stirring for 5 minutes, the product was collected by multiple centrifugations and dried in a 60°C oven for 12 hours. The nano-copper oxide catalyst prepared in Example 5 is designated as Gd / CuO-Q.

[0092] This invention utilizes a quenching method to functionalize the surface of CuO nanoparticles with cerium, forming a Ce / CuO-Q catalyst rich in Ce single-atom sites and some ultrafine CeO2 particles. Quenching CuO in Ce(NO3)3 solution promotes Ce doping into the CuO lattice and generates abundant surface vacancies, thereby modulating the local electronic structure and coordination environment of the catalyst surface. Ce ions in the lattice tend to... 4+ and Ce 3+ Effective circulation between the catalyst and the substrate generates more oxygen vacancies. Simultaneously, the ultrafine CeO2 particles on the CuO surface effectively inhibit the sintering and agglomeration of Cu during MSR, thus extending the catalyst's operating time. Compared to the reference catalyst (Ce / CuO-R) prepared by the conventional impregnation method, Ce / CuO-Q exhibits higher catalytic activity and lower CO selectivity in MSR, achieving 100% methanol conversion and a CO selectivity of 0.052% at 260°C. Notably, this quenching method is also applicable to other rare earth salt solution systems, such as La / CuO-Q, Y / CuO-Q, Nd / CuO-Q, and Gd / CuO-Q catalysts. Therefore, the method provided by this invention offers a novel, simple, and low-cost route for the preparation of high-performance MSR catalysts.

[0093] In this invention, the MSR reaction is measured in a continuous plug flow quartz reactor (e.g., Figure 1(As shown). Before testing, a mixture consisting of an appropriate amount of SiO2 and 300 mg of catalyst was pressed into flakes and then placed in the reforming chamber. A methanol-water solution with an H2O / CH3OH molar ratio of 1.05 was introduced into the evaporation chamber via a Chuangrui CT1000 peristaltic pump (China). Reactor effluents (such as H2, CO2, and CO) were separated by a phase separator and analyzed using an SP-7890 gas chromatograph (China) equipped with TCD and FID. Gas flow rates were determined by an SCal Plus electronic soap bubble flow meter (China), and unreacted reactants were collected by a condenser. Methanol conversion and gaseous product selectivity were evaluated according to the following formula.

[0094]

[0095]

[0096]

[0097]

[0098] In the formula, what do each symbol represent?

[0099] The methanol conversion rate and gaseous product selectivity were evaluated according to formulas (Equations 1-4). MeOH S represents the methanol conversion rate. H2 S CO S CO2 These represent the selectivity for H2, CO, and CO2, respectively. F i It is the molar flow rate of component i in the gas.

[0100] The quenching process for preparing the Ce / CuO-Q catalyst according to this invention is as follows: Figure 2a As shown. The composition of the catalyst was investigated by XRD analysis. Only CuO (PDF#80-1917) diffraction peaks were detected in all catalysts. Figure 2b Due to the low Ce loading and high dispersion, no Ce-related peaks were detected. Compared to other samples, the CuO peak of the Ce / CuO-Q catalyst was slightly shifted to a higher angle. Figure 3 a) This indicates that Ce has been incorporated into the CuO lattice. 3+ Ions. Raman spectroscopy further confirmed the structure of the catalyst. 223 and 613 cm⁻¹ -1 The nearby peaks correspond to the stretching vibrations of the Cu-O bond, while the peak at 277 cm⁻¹... -1 The nearby peaks belong to the bending vibrations of the Cu-O bond. Figure 2c It is worth noting that, compared with CuO-R and Ce / CuO-R, Ce / CuO-Q has a lower efficiency at 223 cm⁻¹. -1 The nearby peaks experienced redshift ( Figure 3 (b) This indicates that quenching in Ce(NO3)3 solution alters the Cu-O coordination environment, thereby generating abundant defect structures.

[0101] Scanning electron microscopy revealed no significant differences in the basic morphology of the CuO-R, Ce / CuO-R, and Ce / CuO-Q catalysts (Figure 4), indicating that quenching does not affect the overall morphology. The morphology and composition of the catalysts were further investigated using a concentrator-corrected spherical aberration TEM. Ultrafine nanoparticles were decorated on the surfaces of Ce / CuO-Q and Ce / CuO-R. Figure 2d and Figure 5 a). Furthermore, N2 adsorption-desorption experiments were conducted on the catalysts to determine their textural properties. As shown in Table 1, the specific surface areas of CuO-R, Ce / CuO-R, and Ce / CuO-Q were 16.3, 21.4, and 22.8 m², respectively. 2 / g.

[0102] Table 1

[0103]

[0104] The increase in specific surface area further demonstrates the formation of ultrafine nanoparticles on the CuO surface. Elemental maps of Ce / CuO-Q and Ce / CuO-R ( Figure 2g -j and Figure 5 It can be observed that Ce species are distributed on the CuO surface. For the Ce / CuO-Q catalyst, the lattice spacing of the large particles (0.234 nm) is considered to be the CuO (111) plane, while the lattice spacing of the ultrafine nanoparticles (0.311 nm) corresponds to the CeO2 (111) plane. Figure 6 e). Importantly, the HAADF-STEM image of Ce / CuO-Q shows the presence of a single Ce atom ( Figure 1 f (marked with a red circle) indicates part of Ce 3+ The CuO is doped into the CuO lattice. Therefore, these results collectively indicate that the CuO structure in the quenched Ce / CuO-Q undergoes some changes compared to Ce / CuO-R, including the incorporation of Ce and the introduction of defects.

[0105] Unpaired electrons and defects are quantified by EPR ( Figure 6 a). A distinct isotropic resonance was observed at g=2.003 in all samples, attributed to unpaired electrons trapped in oxygen vacancies. Furthermore, quantitative results of the EPR signal intensity are shown in [the table below]. Figure 6 b. Oxygen vacancy concentration in Ce / CuO-Q (8.11 × 10¹⁵ spin g) -1 ) are CuO-R (5.14×10 15 Spin g -1) and Ce / CuO-R (6.74×10 15 Spin g -1 The oxygen vacancies were 1.58 times and 1.20 times greater than those in Ce(NO3)3 solution. This result indicates that quenching in Ce(NO3)3 solution generated more oxygen vacancies.

[0106] To investigate the chemical changes induced by quenching, XPS spectral analysis was performed on the samples. The O1s XPS spectra of the three samples could be decomposed into a combination of lattice oxygen (OL, ~529.7 eV), oxygen vacancies (OV, ~531.6 eV), and surface chemisorbed oxygen (OC, ~533.3 eV). Figure 2c Notably, the relative abundance of OV in Ce / CuO-Q (45.9%) was higher than that in CuO-R (37.6%) and Ce / CuO-R (40.8%). In the Cu2p3 / 2 XPS spectrum ( Figure 6 In d), the peak located at 945-938 eV is designated as Cu. 2+ The satellite peaks of Ce / CuO-Q (933.4 eV) are shifted to lower binding energies than those of Ce / CuO-R (933.5 eV), indicating that the quenching process reduces the Cu2p3 / 2 binding energy. 2+ The valence state of Cu species was further verified using CuLMM spectroscopy. Figure 6 e). The peaks located near 917.9 and 916.3 eV are respectively related to Cu. 2+ and Cu + Related to Cu in Ce / CuO-Q. + / (Cu + +Cu 2+ The Cu ratio (25.9%) is higher than that of Ce / CuO-R. + / (Cu + +Cu 2+ The ratio (20.6%) is consistent with the results of Cu2p3 / 2XPS. Furthermore, the Ce3d5 / 2XPS spectrum was fitted with three peaks ( Figure 6 f), where v and v'' are determined to be Ce 4+ ion, v' corresponds to Ce 3+ Ions. Compared to Ce / CuO-R, all peaks of Ce / CuO-Q shift to higher binding energies, Ce... 3+ / (Ce 3+ +Ce 4+ The area ratio of ) decreased from 32.4% to 27.1% (Table 2).

[0107] Table 2

[0108]

[0109] This indicates that quenching induced Cu 2+ To Cu + Electron conversion, accompanied by Ce 3+ To Ce 4+ The oxidation of CuO nanoparticles is thus facilitated by quenching in Ce(NO3)3 solution. This alters the electronic structure and surface properties of CuO nanoparticles, creating oxygen-rich vacancies. This promotes H2O activation and the conversion of C-containing intermediates, thereby enhancing the catalytic activity and CO2 selectivity of the MSR reaction.

[0110] The catalyst after 10 hours of reforming reaction was studied using XRD, XPS, and XAES. XRD patterns ( Figure 7 In (a), diffraction peaks of metallic copper (PDF#04-0836) and Cu2O (PDF#77-0199) were detected, indicating that CuO was reduced to metallic copper and Cu2O. Similarly, no diffraction peaks related to Ce were observed. Furthermore, the Cu2p3 / 2 spectrum was fitted with four peaks ( Figure 7 b). The peak value near 932.9 eV corresponds to Cu. + Or Cu, while the peak value at ~934.8 eV is similar to Cu. 2+ Related. Cu 2+ The appearance of this phenomenon may be due to oxidation of the catalyst surface during the testing process. This is because Cu in the Cu2p3 / 2 spectrum... + The binding energy of Cu is very close to that of Cu, making them difficult to distinguish. Therefore, CuLMM spectroscopy was used to further verify the valence state of the Cu species. The CuLMM spectrum of the catalyst was decomposed into six peaks ( Figure 7 c). The three peaks located near 918.8, 917.7, and 916.5 eV represent Cu, Cu, and Cu, respectively. 2+ and Cu + It is worth noting that the Cu in R-Ce / CuO-Q + The peak area ratio (39.5%) is higher than that of Cu in R-Ce / CuO-R. + Peak area ratio (35.5%) (Table 3)

[0111] Table 3

[0112]

[0113] This implies that the synergistic effect between Cu and Ce species in the quench-induced catalyst is enhanced, thereby promoting the MSR reaction. The oxygen vacancy concentration on the catalyst surface was further investigated using O1s XPS spectroscopy. Figure 8The peak area ratios of Ov were R-Ce / CuO-Q (80.6%) > R-Ce / CuO-R (75.2%) > R-CuO-R (67.1%), indicating that the catalyst initiated by quenching contained more oxygen vacancies during the reaction.

[0114] MSR tests were conducted to evaluate the performance of different catalysts. Since the reaction is endothermic, methanol conversion and CO selectivity increased with increasing temperature. Using methanol conversion at a reforming temperature of 260℃ as the indicator, the order of catalytic activity was found to be Ce / CuO-Q (100%) > Ce / CuO-R (92.1%) > CuO-R (82.7%), accompanied by a CO selectivity order of Ce / CuO-Q (0.052%) < Ce / CuO-R (0.072%) < CuO-R (0.086%). Figure 9 (ab) This indicates that quenching in Ce(NO3)3 solution can improve activity and reduce CO content, attributed to increased defects and the interaction between Ce species and CuO. The catalyst possesses approximately 75% H2 selectivity, meeting its stoichiometric requirements and providing sufficient hydrogen for the fuel cell. Figure 9 c). Considering the excellent performance of Ce / CuO-Q in the tests, this powder was mixed with alumina sol to form a slurry for coating cordierite honeycomb ceramics. Durability tests were then conducted at 260°C. No significant deactivation was observed during 100 hours of operation. Figure 9 d). The methanol conversion rate decreased to 92.3%, and the CO selectivity was between 0.042% and 0.059%, indicating that the structured Ce / CuO-Q catalyst has good stability. It is noteworthy that the catalytic performance of the structured Ce / CuO-Q catalyst is not significantly different from that of the Ce / CuO-Q catalyst. Figure 10 a). Furthermore, the quenched derivative catalyst exhibits superior catalytic performance in MSR compared to the copper-based catalysts reported in Table 4.

[0115] Table 4

[0116]

[0117] The references mentioned in Table 4 are as follows:

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[0127]

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[0128]

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[0129]

[12] E. Baydir, Ö. Aras, Methanol steam reforming in a microchannelreactor coated with spray pyrolysis method for durable Cu / ZnO nanocatalyst, Journal of Analytical and Applied Pyrolysis 158 (2021) 105278.

[0130] Importantly, the MSR performance of CuO nanoparticles quenched in other rare earth salt solutions (La, Y, Nd, and Gd) was also examined. Under the same reaction conditions, the quenched catalyst exhibited higher catalytic activity and lower CO selectivity than CuO-R and Ce / CuO-R. Figure 10 (bf), which verifies the versatility of the quenching method for catalyst preparation.

[0131] The MSR reaction pathway on copper-based catalysts mainly involves three hypothetical pathways with methyl formate (CH3OOCH*), carbon monoxide (CO*), and methyl formate (HCOO*) as surface intermediates. Therefore, Fourier transform infrared spectroscopy was used to further clarify the formation pathway of the Ce / CuO-Q catalyst at 260℃. Figure 11 3425cm -1 and 1603cm -1 The peak at [cm] represents the strong absorption peak of H2O. The stretching vibration peak and symmetry bending peak of the methanol-derived OH bond are located at 3850-3700 cm⁻¹. -1 and 1450cm -1 The CH bond in the methoxy group (C3O*) extends to 2922 cm⁻¹. -1 and 2854cm -1 The CO extension peak in CH3O* is located at 1150-1000 cm⁻¹. -1 2968cm -1 1558cm -1 and 1385cm -1 The peak at approximately 1730 cm⁻¹ represents the CH extension vibration, OCO asymmetry, and symmetrical extension of formate. -1 The peak at that point is the C=O oscillation peak of aldehydes (CH2O*), while the absorption peak of CO2 is concentrated in the 2400-2300 cm⁻¹ range. -1 Furthermore, with the extension of reaction time, 2922cm -1 2400-2300cm -1 1730cm -1 and 558cm -1The continuously increasing peak intensity indicates the gradual accumulation of CH3O*, CO2, CH2O*, and HCOO* on the catalyst surface. Notably, these peak signals stabilize after 9 minutes, suggesting that the adsorption of reactants and intermediates on the catalyst surface has reached saturation. The results show that CH3OH is sequentially converted to CH3O*, CH2O*, and HCOO*, with HCOO* ultimately decomposing into H2 and CO2. Specifically, CH2O* reacts with OH* or O* from H2O to generate HCOO*. Figure 11 The absence of a CO peak indicates that the CO content is below the infrared detection limit, demonstrating that the Ce / CuO-Q catalyst provided by this invention can effectively suppress CO generation during the catalytic process.

[0132] Particle sintering and carbon deposition lead to the deactivation of copper-based catalysts during the MSR reaction. Scanning electron microscopy and Raman spectroscopy analyses were performed on Ce / CuO-Q and U-Ce / CuO-Q catalysts. The results showed that the particle size of U-Ce / CuO-Q was significantly larger than that of Ce / CuO-Q (…). Figure 12 (ab). Meanwhile, the specific surface area of ​​the catalyst used increased from 22.8 m². 2 / g decreased to 3.6m 2 / g

[0133] In addition, the D band (1300-1400cm) without carbon. -1 (disorders and defects) and G-band (1500-1600cm) -1 Graphite or well-structured peaks ( Figure 12 c). Therefore, the sintering and agglomeration of particles lead to a decrease in the activity of Ce / CuO-Q, which may be due to Ostwald ripening, nanoparticle migration and agglomeration during the reaction process.

[0134] In summary, this invention provides a quenching method that induces Ce doping and generates vacancies on the CuO surface, thereby modulating the local electronic structure and coordination environment of the catalyst surface / nearby. Simultaneously, the ultrafine CeO2 particles on the CuO surface effectively prevent the sintering growth of Cu species during MSR, thus extending the catalyst's operating time. Compared to the reference catalyst (Ce / CuO-R) prepared by the conventional impregnation method, Ce / CuO-Q achieves 100% methanol conversion and a CO selectivity of 0.052% at 260°C, exhibiting higher catalytic activity and lower CO selectivity during reforming. After 100 hours of operation, the methanol conversion of the structured Ce / CuO-Q catalyst decreases to 92.3%, and the CO selectivity is 0.042%-0.059%, indicating good catalytic durability. Furthermore, Fourier transform infrared spectroscopy elucidates the evolution of reactants and intermediates on the catalyst surface. Sintering and agglomeration of Ce / CuO-Q lead to catalyst deactivation during the reaction. This quenching method is also applicable to other rare earth salt solution systems, including La / CuO-Q, Y / CuO-Q, Nd / CuO-Q and Gd / CuO-Q catalysts.

Claims

1. A nano-copper oxide catalyst, characterized in that: Nano-sized copper oxide particles are quenched in a rare earth metal salt solution at a temperature of 500-600℃, causing rare earth metal oxides to coat the surface of the nano-sized copper oxide particles. Simultaneously, rare earth metal ions enter the copper oxide lattice on the surface of the nano-sized copper oxide particles, and the Cu in the copper oxide lattice... 2+ Reduced to Cu + It is obtained by increasing the relative abundance of oxygen vacancies on the surface of the nano-copper oxide particles; The rare earth metal salt solution includes a soluble salt solution of Ce, a soluble salt solution of La, a soluble salt solution of Y, a soluble salt solution of Nd, or a soluble salt solution of Gd. The nano-copper oxide catalyst is used for hydrogen production from alcohol reforming; The alcohols include C1-C5 alcohols.

2. The nano-copper oxide catalyst according to claim 1, characterized in that: The particle size of the nano-copper oxide particles is 20-50 nm.

3. The nano-copper oxide catalyst according to claim 1, characterized in that: The soluble salts of Ce include cerium nitrate, cerium chloride, or cerium sulfate; The soluble salts of La include lanthanum nitrate, lanthanum chloride, or lanthanum sulfate; The soluble salts of Y include yttrium nitrate, yttrium chloride, or yttrium sulfate; The soluble salts of Nd include neodymium nitrate, neodymium chloride, or neodymium sulfate; The soluble salts of Gd include gadolinium nitrate, gadolinium chloride, or gadolinium sulfate.

4. The nano-copper oxide catalyst according to claim 1, characterized in that: The relative abundance of oxygen vacancies on the surface of the nano-copper oxide catalyst is 45%-46%.

5. The nano-copper oxide catalyst as described in claim 1, characterized in that: The concentration of the rare earth metal salt solution is 0.25-0.35M.

6. The method for preparing the nano-copper oxide catalyst according to claim 1, characterized in that: Includes the following steps: The nano-copper oxide particles are heat-treated, then quenched in a rare earth metal salt solution, and the product is collected and dried to obtain the final product.

7. The method for preparing the nano-copper oxide catalyst as described in claim 6, characterized in that: The mass-to-volume ratio of nano-copper oxide particles to rare earth metal salt solution is 1.3-1.6 g: 25 mL; The heat treatment temperature is 500-600℃; The heating rate of the heat treatment is 5-6℃ / min; The heat treatment time is 2-3 hours.

8. The method for preparing the nano-copper oxide catalyst as described in claim 6, characterized in that: The drying temperature is 60-70℃; The drying time is 10-12 hours.

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