Boosting Pt atom efficiency by reinforcing the synergy with extra Sn sites encapsulated in MFI zeolite for the aromatization of n-hexane

Abstract

Catalytic reforming of alkanes is of great significance for increasing the production of value-added aromatics; however, noble metal platinum of high cost has to be used and still suffers from considerable issues of poor reactivity and stability. To maximize the atom utilization efficiency of platinum catalysts by enhancing their intrinsic activity, we developed a siliceous MFI zeolite-confined platinum–tin catalyst with highly dispersed Pt clusters and extra Sn-based Lewis acid sites via a facile hydrothermal process. The channels of the zeolite are conducive to the optimal and stable electronic interaction between platinum and tin, rendering positively charged Pt^δ+ sites with boosted dehydrogenation capability and correspondingly improved specific activity. The neighboring Sn-Lewis acid sites grafted on the zeolite framework, in synergy with the well-regulated Pt^δ+ sites, afford the promoted adsorption and stabilization of alkene intermediates, thereby favoring the subsequent cyclization and deep dehydrogenation. This catalyst with balanced cooperation of metal and acid sites not only contributes to a top-level performance of up to 856.5 g_aromatics g_Pt⁻¹ h⁻¹ in the n-hexane reforming reaction at 550 °C and 0.1 MPa, but also exemplifies a promising strategy to construct highly efficient noble metal centers with confined microenvironments and synergistic acid sites.