Elucidation of Active Sites in Aldol Condensation of Acetone over Single-Facet Dominant Anatase TiO<sub>2</sub> (101) and (001) Catalysts
Fan Lin, Huamin Wang, Yuntao Zhao, Jia Fu, Donghai Mei, Nicholas R. Jaegers, Feng Gao, Yong Wang
Abstract
H is a kinetically relevant step, which is consistent with kinetic and isotopic studies as well as DFT calculations. The {001} facet showed a lower apparent activation energy (or higher activity) than the {101} facet. This is likely caused by the weaker Lewis acid and Brønsted base strengths of the {001} facet which favors the reprotonation-desorption of the coupled intermediate, making the C-C coupling step more exothermic on the {001} facet and resulting in an earlier transition state with a lower activation barrier. It is also possible that the {001} facet has a smoother surface configuration and less steric hindrance during intermolecular C-C bond formation than the {101} facet.