Understanding the role of TiO2 crystal structure on the enhanced activity and stability of Ru/TiO2 catalysts for the conversion of lignin-derived oxygenates

Abstract

Although Ru catalysts supported on reducible oxides such as TiO₂ hold significant promise for the deoxygenation of biomass derived oxygenates, a significant drawback is their instability under oxidation conditions necessary for catalyst regeneration. In this contribution, the role of TiO₂ crystal structure on resistance to metal particle sintering during calcination treatments at 400 and 500 °C is investigated. The resulting impact of the calcination temperature and TiO₂ support phase for the conversion of guaiacol at 400 °C under atmospheric pressure of hydrogen over supported Ru catalysts is presented. Results suggest that the rutile TiO₂ phase plays an important role in stabilizing Ru particles during calcination pretreatment in comparison with anatase supported Ru catalysts. Furthermore, rates normalized to the area of the support and the Ru suggest that the high activity of Ru/TiO₂ systems for guaiacol conversion is attributed to defect sites created by hydrogen spillover from the Ru metal to the reducible TiO₂ as opposed to only the sites located at the Ru/TiO₂ interface.