DFT study on CO oxidative coupling to DMO over Pd4/TiO2 and Pd4/TiO2-Ov: A role of oxygen vacancy on support.

Graphical abstract Highlights • CO oxidative coupling on Pd 4 /TiO 2 and Pd 4 /TiO 2 -O v were studied by DFT method. • The stronger interaction between Pd 4 and TiO 2 -O v than Pd 4 and TiO 2. • Pd 4 /TiO 2 -O v exhibits a high activity for CO oxidative coupling to DMO. Abstract The reaction mechanisms for CO oxidative coupling to DMO on Pd 4 supported on TiO 2 (0 0 1) catalysts were studied by using the density functional theory calculations with a Hubbard U correction (DFT + U). Two different supports including perfect TiO 2 (0 0 1) and oxygen vacancy TiO 2 (0 0 1) were investigated. The interaction between Pd 4 and supports showed that the binding energy of Pd 4 cluster with oxygen vacancy TiO 2 (0 0 1) was stronger than that with the perfect TiO 2 (0 0 1), and the relatively weak adsorption energy of CO was obtained on Pd 4 /TiO 2 -O v , implied that it was easier for CO removing and reacting. In addition, reaction mechanisms of CO oxidative coupling to DMO on Pd 4 /TiO 2 and Pd 4 /TiO 2 -O v were studied, and the Pd 4 /TiO 2 -O v catalyst showed higher activity than Pd 4 -TiO 2. Moreover, compared with Pd(1 1 1), Pd 4 /TiO 2 -O v not only reduced the amount of Pd, but also improved the activity of CO oxidative coupling to DMO. However, DMO and DMC were competitive products on Pd 4 /TiO 2 and Pd 4 /TiO 2 -O v , showed that they were with poor selectivity to DMO. [ABSTRACT FROM AUTHOR]