Tuning the Selectivity in the Nonoxidative Alkane Dehydrogenation Reaction by Potassium-Promoted Zeolite-Encapsulated Pt Catalysts

Abstract

High Resolution Image Download MS PowerPoint Slide The significance of the nonoxidative dehydrogenation of middle-chain alkanes into corresponding alkenes is increasing in the context of the world’s declining demands on transportation fuels and the growing demand for chemicals and materials. The middle-chain alkenes derived from the dehydrogenation reaction can be transformed into value-added chemicals in downstream processes. Due to the presence of multiple potential reaction sites, the reaction mechanism of the dehydrogenation of middle-chain alkanes is more complicated than that in the dehydrogenation of light alkanes, and there are few prior studies on elucidating their detailed structure–reactivity relationship. In this work, we have employed Pt catalysts encapsulated in pure-silica MFI zeolite crystallites as model catalysts and studied how the catalytic performances for dehydrogenation of n -pentane can be modulated by the K + promotor in the Pt-MFI catalyst. A combination of comprehensive structural characterizations by aberration-corrected electron microscopy, X-ray absorption spectroscopy, in situ CO-IR, X-ray photoelectron spectroscopy, and kinetic studies shows that K + promoter can not only influence the particle size but also modify the electronic properties of Pt species, which further affect the activity and selectivity in the dehydrogenation of n -pentane.