Optimizing zeolite stabilized Pt-Zn catalysts for propane dehydrogenation

Abstract

Zeolite stabilized Pt-Zn catalyst has been developed for propane direct dehydrogenation with propane conversion close to the equilibrium and a very low deactivation rate of 0.0018h −1 at 823 K. Propane dehydrogenation (PDH) provides an alternative route to non-petroleum based propylene and eligible catalysts with good overall performance are still being explored. Herein, we report the construction of zeolite stabilized Pt-Zn catalysts Pt-Zn/Si-Beta for PDH. Characterization results from transmission electron microscopy (TEM), ultraviolet–visible (UV–vis) and Fourier transform infrared (FTIR) spectroscopy reveal that highly-dispersed Zn species are stabilized by the silanols from zeolite framework dealumination, which then act as the anchoring sites for Pt species. The close contact between Pt-Zn species and the electronic interaction thereof make Pt-Zn/Si-Beta robust PDH catalysts. Under optimized conditions, a high propylene production rate of 4.11 m o l m o l P t - 1 s - 1 , high propylene selectivity of 98% and a sustainable deactivation rate of ~ 0.02 h −1 can be simultaneously achieved at 823 K. Coke deposition is not the key reason for the catalytic deactivation, while the loss of Zn species and the resulting aggregation of Pt species under high temperatures are responsible for the irreversible deactivation of Pt-Zn/Si-Beta catalyst in PDH reaction.