Pt–ZnO_<i>x</i> Interfacial Effect on the Performance of Propane Dehydrogenation and Mechanism Study

Abstract

Bimetallic Pt-based catalysts, for example, PtZn and PtSn catalysts, have gained significant attention for addressing the poor stability and low selectivity of pristine Pt catalysts over propane dehydrogenation (PDH). However, the structures of the active sites and the corresponding catalytic mechanism of PDH are still elusive. Here, we demonstrate a spatially confined Pt-Zn<i>_m</i>O_<i>x</i>@RUB-15 catalyst (where "<i>m</i>" is the mole ratio of Zn/Pt and RUB-15 is a layered silica), which exhibited high catalytic activity, ultrahigh selectivity (>99%), and resistance to coking at 550 °C for PDH. Significantly different from the preliminary studies over the PtZn catalysts, through the assistance of quasi-<i>in situ</i> X-ray photoelectron spectroscopy (XPS), <i>in situ</i> Fourier transform infrared spectroscopy (CO-FTIR), <i>in situ</i> X-ray absorption spectroscopy (XAS), and CO titration, we discovered that the active sites for PDH were the Pt-ZnO_<i>x</i> interfaces, characterized by a structure of Pt^δ+-Zn²⁺-O-Si. Density functional theory (DFT) calculations showed that Pt atoms positioned at Pt-ZnO_<i>x</i> interfaces with coordinatively unsaturated ZnO_<i>x</i> sites facilitate the C-H bond breaking of propane while concurrently suppressing deep dehydrogenation processes. This study suggests that engineering the interfaces of Pt-metal oxides under spatially confined conditions holds promise for developing highly efficient Pt-based catalysts for light alkane dehydrogenation.