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

Shilong Chen; Ali M Abdel-Mageed; Dan Li; Joachim Bansmann; Sebastian Cisneros; Johannes Biskupek; Weixin Huang; R Jürgen Behm

doi:10.1002/anie.201903882

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

Angew Chem Int Ed Engl. 2019 Jul 29;58(31):10732-10736. doi: 10.1002/anie.201903882. Epub 2019 Jun 27.

Authors

Shilong Chen¹, Ali M Abdel-Mageed¹, Dan Li², Joachim Bansmann¹, Sebastian Cisneros¹, Johannes Biskupek³, Weixin Huang², R Jürgen Behm¹

Affiliations

¹ Institute of Surface Chemistry and Catalysis, Ulm University, 89069, Ulm, Germany.
² Hefei National Laboratory for Physical Sciences at the Microscale, Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes and Department of Chemical Physics, University of Science and Technology of China, 230026, Hefei, P. R. China.
³ Central Facility for Electron Microscopy, Ulm University, 89069, Ulm, Germany.

PMID: 31095821
DOI: 10.1002/anie.201903882

Abstract

Ru/TiO₂ catalysts exhibit an exceptionally high activity in the selective methanation of CO in CO₂ - and H₂ -rich reformates, but suffer from continuous deactivation during reaction. This limitation can be overcome through the fabrication of highly active and non-deactivating Ru/TiO₂ catalysts by engineering the morphology of the TiO₂ support. Using anatase TiO₂ nanocrystals with mainly {001}, {100}, or {101} facets exposed, we show that after an initial activation period Ru/TiO₂ -{100} and Ru/TiO₂ -{101} are very stable, while Ru/TiO₂ -{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 TiO₂ -{100} and TiO₂ -{101} supports stabilize flat Ru nanoparticles, while on TiO₂ -{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/TiO₂ -{001}.

Keywords: CO methanation; Ru/TiO2; metal-support interactions; morphology engineering; particle shape.