Authors: Tangsheng Zou, Elisavet Tazedaki, Konstantin M. Engel, Yung‐Tai Chiang, Mikhail Agrachev, Katja Raue, Frank Krumeich, Henrik Eliasson, Rolf Erni, Wendelin J. Stark, Robert N. Grass, Thaylan Pinheiro Araújo, Javier Pérez‐Ramírez
Published: 2025-03-18
Source: Full article
AbstractIndium‐zirconium (InZrOx) and zinc‐zirconium oxides (ZnZrOx) have emerged as highly selective and stable catalysts for CO2 hydrogenation to methanol, a versatile energy carrier. However, the disparity in synthesis methods, catalyst formulations, and structures previously studied precludes quantitative comparisons between the two families. Herein, a rigorous framework is pioneered to benchmark InZrOx and ZnZrOx materials prepared by a standardized flame spray pyrolysis synthesis platform, enabling consistently high surface areas and tunable metal speciation ranging from isolated atoms (<5 mol%) to predominantly nanoparticles (>10 mol%). Isolated indium and zinc species are commonly identified to be optimal for activity and methanol selectivity in their respective families, maximizing CO2 and H2 activation abilities. InZrOx outperforms ZnZrOx across speciations and is less structure sensitive, as deviations from atomic dispersion is less detrimental on performance for the former. Focusing on representative catalysts featuring saturation of isolated species, the higher activity of 5 mol% InZrOx over its ZnZrOx counterpart is linked to differences in surface oxygen vacancy chemistry, a lower degree of product inhibition, and more facile hydrogenation of the formate intermediate to methoxy. The identification of reactivity descriptors governing both families facilitates the development of unified guidelines in designing reducible oxide catalysts.