Revealing the Janus Character of the Coke Precursor in the Propane Direct Dehydrogenation on Pt Catalysts from a kMC Simulation

Abstract

As the commercial catalyst in the propane direct dehydrogenation (PDH) reaction, one of the biggest challenges of Pt catalysts is coke formation, which severely reduces activity and stability. In this work, a first-principles DFT-based kinetic Monte Carlo simulation (kMC) is performed to understand the origin of coke formation, and an effective method is proposed to curb coke. The conventional DFT calculations give a complete description of the reaction pathway of dehydrogenation to propylene, deep dehydrogenation, and C–C bond cracking. The rate-limiting step is identified as the dissociative adsorption of propane. Moreover, a comparison between different exchange-correlation functionals indicates the importance of van der Waals corrections for the adsorption of propane and propylene. The lateral interactions between the surface adsorbates are significant, which implies that mean field microkinetic modeling might not adequately describe the reaction process. There are two distinct stages in PDH, which ar...