Tracking Dynamics of Supported Indium Oxide Catalysts in CO Hydrogenation to Methanol by In Situ TEM.

Supported reducible oxides, such as indium oxide on monoclinic zirconia (InO/m-ZrO), are promising catalysts for green methanol synthesis via CO hydrogenation. Growing evidence suggests that dynamic restructuring under reaction conditions plays a crucial but poorly understood role in catalytic performance. To address this, the direct visualization of the state-of-the-art InO/m-ZrO catalyst under CO hydrogenation conditions (T  =  553 K, P  =  1.9 bar, CO:H  =  1:4) is pioneered using in situ scanning transmission electron microscopy (STEM), comparing its behavior to InO on supports with similar (tetragonal, t-ZrO or anatase TiO) or lower (LSm-ZrO) surface areas. Complementary in situ infrared spectroscopy and catalytic tests confirm methanol formation under equivalent conditions. A machine-learning-based difference imaging approach differentiates and ranks restructuring patterns, revealing that partially reduced InO species on m-ZrO undergo cyclic aggregation-redispersion via atomic surface migration, maintaining high active phase dispersion. High-resolution ex situ STEM analysis further shows the epitaxial formation of InO mono- and bilayers on (100) m-ZrO facets, highlighting strong oxide-support interactions. In contrast, sintering prevails on t-ZrO, a-TiO, and low-surface m-ZrO, correlating with lower methanol productivity. This work underscores the pivotal role of oxide-support interfacial interactions in the reaction-induced restructuring of InO species and establishes a framework for tracking nanoscale catalyst dynamics.