Highly efficient Sn-modified Pt/KY catalyst for n-octane reforming: the synergistic effect of Pt in different electronic states

Abstract

Effectively converting straight-chain paraffin into aromatics plays an essential role in improving gasoline quality, yet the reforming of larger-sized alkanes remains a major challenge, including hydrogenolysis and deactivation. Herein, a Sn-modified Pt-based catalyst with non-acidic KY zeolite as support is obtained using atomic layer deposition, which exhibits superior aromatization ability and stability. The selectivity towards aromatics over the resulting Pt/KYSn(1) catalyst is up to 92.7% with n-octane conversion of 96.1%, more remarkable than in previous reports. Various characterizations reveal that Sn modification induces the formation of electron-deficient Pt clusters, favorable for the activation of C–H bonds in n-octane, and therefore facilitates the dehydrogenation of n-octane to octene intermediates. In addition, the crucial role of electron-rich Pt species on n-octane reforming is also confirmed, probably resulting from the initial dehydrogenation of n-octane on electron-deficient Pt clusters and the cyclization of octene on electron-rich Pt clusters. The cooperative work of electron-deficient and electron-rich Pt species promotes the Pt/KYSn(1) catalyst to be one of the most superior n-octane aromatization catalysts reported up till now. This work provides a route to obtaining a highly efficient alkane dehydrocyclization catalyst.