Tuning selectivity of CO2 hydrogenation by modulating the strong metal–support interaction over Ir/TiO2 catalysts

Abstract

Exploration of highly selective catalysts for CO₂ hydrogenation remains a great challenge since the reduction of CO₂ over the supported metal catalysts may give rise to various products in response to the modulation of the chemical state of active sites. Herein, by varying the pretreatment temperature of iridium/titanium oxide (Ir/TiO₂) catalysts, the selectivity of CO₂ hydrogenation from CH₄ to sole production of CO can be finely tuned. The change of product selectivity is achieved in such a way that the selectivity greatly depend on the formation of a reduced TiO_x overlayer around Ir nanoparticles (NPs) as originated from the strong metal–support interaction (SMSI). With only a weak reduction treatment, the exposed Ir NPs without a TiO_x coating promote CH₄ production exclusively. After the catalyst undergoes a high temperature reduction, the evolution of the TiO_x coating over Ir NPs shows a preference for CO production with an inhibition of further methanation. This study not only provides insights into the regulation of CO₂ hydrogenation by SMSI, but also serves as an effective approach to tuning other catalytic processes.