Vietnam Journal of Catalysis and Adsorption

RESEARCH PAPER

open access logo 200x200Influence of Water on the Activation of Methanol over Platinum: A DFT Study

Trinh Quang Thang1,2,This email address is being protected from spambots. You need JavaScript enabled to view it., Dao Quoc Tuy1, Huynh Dang Chinh1, Pham Thanh Huyen1,This email address is being protected from spambots. You need JavaScript enabled to view it.

1 School of Chemical Engineering, Hanoi University of Science and Technology, 1 Dai Co Viet St., Hanoi, Vietnam.
2 Cambridge Centre for Advanced Research and Education in Singapore (CARES), Campus for Research Excellence and Technological Enterprise (CREATE), 1 Create Way, 138602 Singapore.

ABSTRACT

Water plays an active role in aqueous phase catalytic reactions. In this study, the effect of water on the chemical activity and selectivity of the C-H and O-H bond activation in methanol on Pt was studied using density functional theory. On clean terraces in gas phase, C-H and O-H activations are competitive with energy barriers of 88 and 82 kJ/mol, respectively. The selectivity however reverses in the presence of a monolayer of water and the O-H activation barrier is increased to 128 kJ/mol. The C-H activation barrier of 108 kJ/mol is less affected and the CH activation becomes the dominant channel, in agreement with experiments at low potentials. At higher potentials, the presence of surface hydroxyl groups opens a new hydrogen abstraction pathway with a very low barrier for O-H bond activation of 9 kJ/mol. Hydroxyl groups can also activate C-H bonds and hydrogen abstraction in methoxy has a barrier of 67 kJ/mol, but is however higher than the barrier for direct C-H activation of 36 kJ/mol.

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