Modified Pt (2 1 1) and (3 1 1) surfaces towards the dehydrogenation of methylcyclohexane to toluene: A density functional theory study

Spin polarized van der Waals corrected density functional theory calculations on the pristine and modified Pt (2 1 1) and Pt (3 1 1) step surfaces were performed towards the dehydrogenation of methylcyclohexane to toluene. The reaction of energy for fully dehydrogenating methylcyclohexane to toluene on the pristine Pt (2 1 1) and Pt (3 1 1) step surfaces are 0.98 eV and 0.78 eV respectively. The pristine Pt (3 1 1) step surface has lower dehydrogenation energetics compared to the Pt (1 1 1) surface. The implication is that higher index surface would result in the overall increase in the activity, however the step surfaces have lower surface area. The current investigation show that the overall dehydrogenation reaction energetics is lowered by surface modifiers on the Pt step surfaces and the Si, P and Sn surface modifiers at low concentrations (n = 1, 2) resulted in improved catalytic dehydrogenation of methylcyclohexane on Pt (2 1 1) and Pt (3 1 1) step surfaces compared to S surface modifier. We obtained that the catalytic dehydrogenation reaction energetics can be improved considering low concentration of surface catalytic site blockers, which are applied as surface modifiers. The study motivates experimental investigations on the application of Si, P and Sn as surface modifiers for the catalytic dehydrogenation of methylcyclohexane.