Morphology‐Engineered Highly Active and Stable Ru/TiO₂ Catalysts for Selective CO Methanation

Abstract

Abstract Ru/TiO 2 catalysts exhibit an exceptionally high activity in the selective methanation of CO in CO 2 ‐ and H 2 ‐rich reformates, but suffer from continuous deactivation during reaction. This limitation can be overcome through the fabrication of highly active and non‐deactivating Ru/TiO 2 catalysts by engineering the morphology of the TiO 2 support. Using anatase TiO 2 nanocrystals with mainly {001}, {100}, or {101} facets exposed, we show that after an initial activation period Ru/TiO 2 ‐{100} and Ru/TiO 2 ‐{101} are very stable, while Ru/TiO 2 ‐{001} deactivates continuously. Employing different operando/in situ spectroscopies and ex situ characterizations, we show that differences in the catalytic stability are related to differences in the metal–support interactions (MSIs). The stronger MSIs on the defect‐rich TiO 2 ‐{100} and TiO 2 ‐{101} supports stabilize flat Ru nanoparticles, while on TiO 2 ‐{001} hemispherical particles develop. The former MSIs also lead to electronic modifications of Ru surface atoms, reflected by the stronger bonding of adsorbed CO on those catalysts than on Ru/TiO 2 ‐{001}.