Tuning the Selectivity\nin the Nonoxidative Alkane\nDehydrogenation Reaction by Potassium-Promoted Zeolite-Encapsulated\nPt Catalysts

The significance of the nonoxidative dehydrogenation\nof middle-chain\nalkanes into corresponding alkenes is increasing in the context of\nthe world’s declining demands on transportation fuels and the\ngrowing demand for chemicals and materials. The middle-chain alkenes\nderived from the dehydrogenation reaction can be transformed into\nvalue-added chemicals in downstream processes. Due to the presence\nof multiple potential reaction sites, the reaction mechanism of the\ndehydrogenation of middle-chain alkanes is more complicated than that\nin the dehydrogenation of light alkanes, and there are few prior studies\non elucidating their detailed structure–reactivity relationship.\nIn this work, we have employed Pt catalysts encapsulated in pure-silica\nMFI zeolite crystallites as model catalysts and studied how the catalytic\nperformances for dehydrogenation of <i>n</i>-pentane can\nbe modulated by the K<sup>+</sup> promotor in the Pt-MFI catalyst.\nA combination of comprehensive structural characterizations by aberration-corrected\nelectron microscopy, X-ray absorption spectroscopy, in situ CO-IR,\nX-ray photoelectron spectroscopy, and kinetic studies shows that K<sup>+</sup> promoter can not only influence the particle size but also\nmodify the electronic properties of Pt species, which further affect\nthe activity and selectivity in the dehydrogenation of <i>n</i>-pentane.