Insights into the alloy-support synergistic effects for the CO2 hydrogenation towards methanol on oxide-supported Ni5Ga3 catalysts: An experimental and DFT study

• Published in: Applied catalysis. B, Environmental Environmental, 2022-03, Vol.302, p.120842, Article 120842
• Main Authors: Rasteiro, Letícia F., De Sousa, Rafael A., Vieira, Luiz H., Ocampo-Restrepo, Vivianne K., Verga, Lucas G., Assaf, José M., Da Silva, Juarez L.F., Assaf, Elisabete M.
• Format: Article
• Language: English
• Subjects: Alloys; Carbon dioxide; Carbon dioxide emissions; Catalysts; Cerium oxides; CO2 hydrogenation; Density functional theory; Emissions; Gallium base alloys; Hydrogenation; Intermediates; Mathematical analysis; Methanol; Ni5Ga3 alloy; Optimization; Reaction intermediates; Reaction mechanism; Reaction mechanisms; Silicon dioxide; Strong interactions (field theory); Structural analysis; Synergistic effect; Zirconium dioxide
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2021.120842

Supported Ni-Ga alloys have emerged as potential catalyst to mitigate CO2 emissions by its conversion into methanol at mild conditions, however, its performance depends on the optimization of the alloy-support effects, which is unclear up to now. Herein, we investigate the influence of alloy-support synergy in the catalytic performance of Ni5Ga3 supported on SiO2, CeO2, and ZrO2, by combining in-depth structural, chemical and spectroscopic characterization and density functional theory (DFT) calculations. In situ DRIFTS confirmed further hydrogenation of key reaction intermediates in Ni5Ga3/ZrO2 surface, while weak CO2 adsorption in Ni5Ga3/SiO2 avoided intermediate stabilization on the surface and, strong interaction with Ni5Ga3/CeO2 poisoned interface active sites. Additionally, the relative energies of reactants and key intermediates in the three distinct regions of the catalyst (support surface, alloy surface, and alloy-support interface), calculated through DFT, allowed us to propose a reaction mechanism for the most promising catalyst, Ni5Ga3/ZrO2. [Display omitted] •Support effects on the performance of Ni5Ga3 catalysts were evaluated during CO2 hydrogenation to methanol.•Weak CO2 adsorption in Ni5Ga3/SiO2 limited the methanol production through an alloy surface mechanism.•The strong interaction of CO2 and reaction intermediates in the Ni5Ga3/CeO2 interface poisoned the active sites.•Ni5Ga3/ZrO2 interface was capable of stabilizing key reaction intermediates and promote further hydrogenation to methanol.•Combined in situ spectroscopy analysis and DFT calculations allowed to propose a reaction mechanism for Ni5Ga3/ZrO2 system.