Effects of n‑Butane Coverage on Its Catalytic Dehydrogenation: A Density Functional Theory Study on the Pt(111) Surface

Butane dehydrogenation at different butane coverages on the Pt(111) surface have been investigated using density functional theory (DFT) calculations. The adsorption of intermediates on the surface with a lower coverage is stronger, resulting in a more facile activation of C–H. Based on the microkinetic model, it was found that the coverage has a strong influence on the reaction activity but no obvious effect on the reaction pathway. Analysis of the degree of rate control reveals that the rate-determining steps for each product are similar at different coverages. Furthermore, at lower coverage, the energy barrier for butadiene desorption is higher than that for the preceding C–H bond cleavage step, resulting in deeper dehydrogenation. Moreover, C–C bond cleavage was found to primarily occur from the products obtained from deep dehydrogenation of butadiene. Our results help to interpret experimental butane dehydrogenation and provide ways to improve catalyst performance.