Oxidative dehydrogenation of propane over Pt–Sn/Si-beta catalysts: key role of Pt–Sn interaction

Abstract

Bimetallic Pt–Sn catalysts supported on dealuminated Si-beta zeolite were prepared via wet impregnation and the nanoscale close contact between Pt and Sn species in Pt–Sn/Si-beta was confirmed by electron microscopy analyses. Characterization results from temperature-programmed reduction by hydrogen (H₂-TPR) and X-ray photoelectron spectroscopy (XPS) indicated the interaction between Pt and Sn species, and the electron transfer from SnO₂ to Pt species was clearly demonstrated by the XPS and FTIR spectra of CO adsorption. The as-prepared bimetallic Pt–Sn/Si-beta catalyst exhibited remarkable performance in the oxidative dehydrogenation of propane (ODHP), in great contrast to monometallic Pt/Si-beta and Sn/Si-beta. Typically, a stable propane conversion of 37% and a propylene selectivity of 75% could be simultaneously achieved on 0.5Pt–5Sn/Si-beta at a reaction temperature of 773 K. Temperature-programmed desorption experiments revealed that the propane adsorption significantly strengthened while the propylene adsorption weakened on the bimetallic Pt–Sn/Si-beta catalyst, which accordingly resulted in its remarkable performance in ODHP reaction. The spatial separation of Pt and Sn species was observed on the used Pt–Sn/Si-beta catalyst and it was responsible for the catalytic deactivation.