Nanoparticulate Ru on TiO2 exposed the {100} facets: Support facet effect on selective hydrogenation of benzene to cyclohexene

Support facet effect of supported metal catalysts for conversion of environmentally toxic feedstock to value-added product is challenging but of significant importance for the understanding of the reaction mechanism and accordingly rational design of newly high-efficient catalytic materials. We report here the effect of the exposed degree of TiO2 {1 0 0} facets, which was facilely tuned by hydrothermal temperature, on benzene selective hydrogenation to cyclohexene over TiO2-supported nanoparticulate Ru catalysts. It is found that the Ru/TiO2 catalyst exposed the most {1 0 0} facets exhibited slightly lower intrinsic activity, but unexpectedly highest selectivity towards cyclohexene (initial selectivity of 93%). A positively linear correlation between the initial selectivity to cyclohexene and the amount of surface OH groups on the Ru/TiO2 catalysts, which was determined by the exposed degree of TiO2 {1 0 0} facets, was identified. This linearity rationalizes the selectivity enhancement of the Ru/TiO2 catalyst exposed more {1 0 0} facets since the surface OH groups functioned in increasing the hydrophilicity of the catalysts, decreasing the type of adsorption sites of cyclohexene, and blocking the chemisorption sites of cyclohexene. (C) 2018 Elsevier Inc. All rights reserved.