Interface-enhanced catalytic performance of TiO2-supported Cu and Au for dimethyl oxalate hydrogenation: A comparative microkinetic analysis.

Sub-nanometer-sized Cu 6 and Au 6 clusters are stably anchored on the oxygen-deficient anatase TiO 2 surface, where Cu 6 -(V O)-TiO 2 shows high catalytic activity and satisfactory selectivity toward MG. [Display omitted] • The size and structure of stable Cu and Au clusters on TiO 2 are determined. • Oxygen vacancies can stabilize sub-nanometer-sized metal clusters. • Ti 5c and Cuδ+/Auδ- ions are coordinated to reaction intermediates. • The activity of Cu 6 -(V O)-TiO 2 (1 0 1) shows strong temperature sensitivity. • Cu-TiO 2 has good catalytic performance for DMO hydrogenation and MG production. The electronic structures of Cu-TiO 2 and Au-TiO 2 and their catalytic behaviors in the hydrogenation of dimethyl oxalate (DMO) have been studied by the stochastic surface walking-global neural network potential method, density functional theory calculation, and microkinetic analysis. Calculated results indicate that metal clusters on the pristine and oxygen-deficient TiO 2 are mostly coordinated to O 2c ions, and the defective surface may provide additional oxygen vacancies for Cu 6 and Au 6 cluster anchoring. It turns out that the interfacial Ti 5c and Cuδ+/Auδ- ions provide adsorption and hydrogenation sites for the reaction intermediates with unsaturated O and C atoms, respectively. The turnover frequency for DMO consumption is much higher on Cu-TiO 2 than on Au-TiO 2 , Cu(1 1 1), and Cu(2 1 1) at 443.15 K and 20 bar of total pressure. Given the satisfactory methyl glycolate (MG) selectivity, the Cu-TiO 2 catalyst has the potential to act as an excellent catalyst for the selective MG production. [ABSTRACT FROM AUTHOR]