Density functional theory studies on dehydrogenation of methanol to formaldehyde on Pt(111) surface at different coverage

Platinum metal exhibits excellent catalytic activity and selectivity in many important chemical reactions. In this paper, density functional theory is used to study the adsorption configurations of oxygen in methanol on Pt(1 1 1) surface and dehydrogenation reaction (CH3OH -> CH2O) at different coverage. It is found that methanol molecules prefer to adsorb at the top position of Pt(1 1 1) at various coverage levels. With the coverage increases, the adsorption capacity of methanol decreases rapidly, and then tends to flatten until the coverage reaches 1/6. The product of CH2O is formed by two-step dehydrogenation process. The energy barrier for both dehydrogenations increase first and then decreases with increasing coverage. The lowest energy barrier for both dehydrogenations occurs on the Pt(1 1 1) surface with coverage of 1/6 (Ea, O-H = 0.66 eV, Ea, C-H = 0.16 eV). Therefore, coverage of 1/6 is the optimal coverage for CH3OH generating CH2O on the Pt(1 1 1) surface.