Cation rearrangement at tetrahedral sites in the Cu/ZnAl2O4 spinel enhancing CO2 hydrogenation to methanol

• Published in: Applied catalysis. B, Environmental Vol. 362; p. 124742
• Main Authors: Song, Lixin, Liu, Guobin, Qu, Zhenping
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.03.2025
• Subjects: Cation arrangement; CO2 hydrogenation; Formate intermediates; MSI; ZnAl2O4 spinel; MSI; Formate intermediates; Cation arrangement; CO2 hydrogenation; ZnAl2O4 spinel
• ISSN: 0926-3373
• DOI: 10.1016/j.apcatb.2024.124742

Cu/ZnAl2O4 spinel is a promising catalyst for CO2-to-methanol due to its dual-site H2 activation. However, controlling surface properties and metal-support interactions (MSI) through the coordination environment of spinel cations remains underexplored. Herein, the occupancy of Zn2+ and Al3+ cations in Cu/ZnAl2O4 spinel is fine-tuned by manipulating the calcination atmosphere. More disordered structures (AlO4 and ZnO6) observed on the CZA-Ar catalyst benefit the creation of oxygen vacancies and surface hydroxyl groups, which facilitate the formation of highly dispersed small-sized Cu species. This enhances MSI and hydrogen spillover effects, thereby boosting CO2 conversion and the space-time yield (STY) of methanol. High-pressure in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) results reveal that the crucial formate intermediates form at tetrahedral sites in ZnAl2O4 spinel, with more Al-HCOO- species observed on the CZA-Ar catalyst due to the formation of AlO4. This work advances the understanding of spinel catalysts in CO2 hydrogenation to methanol. [Display omitted] •The cationic occupation of spinel can be fine-tuned by the calcination atmosphere.•More disordered AlO4 and ZnO6 structures can be observed on the CZA-Ar catalyst.•Disordered structures boost OV and OH* groups, enhancing MSI and H spillover.•Formate intermediate species tend to form at tetrahedral sites in ZnAl2O4 spinel.