TiO2-supported catalysts with ZnO and ZrO2 for non-oxidative dehydrogenation of propane: mechanistic analysis and application potential

Non-oxidative dehydrogenation of propane is one of the most promising technologies for propene production in terms of environmental impact and sustainability. The purpose of the present study was to develop environmentally friendly and low-cost alternatives to currently applied Pt- or CrOx-based catalysts. Rutile TiO2-based catalysts with supported ZnOx and ZrOx species were established to show promising performance under industrially relevant conditions. The amount of propene produced within 3 h on propane stream at 550 °C over the optimized catalyst with 2 wt% Zn and 5.6 wt% Zr is close to that obtained over commercial-like K–CrOx/Al2O3 and the state-of-the-art Cu/YZrOx catalyst. The selectivity to propene over our catalyst was about 95% at a propane conversion of about 23%. The kind of active sites and the effect of ZrO2 addition on catalyst performance and physicochemical properties were elucidated owing to the application of complementary characterisation techniques such as XRD, N2 physisorption, HRTEM, EDX, XPS, X-ray absorption spectroscopy, NH3-TPD, CO-TPR, Raman and O2-TPO. ZnOx clusters with 1–3 Zn atoms were concluded to be the active sites. ZrO2 enhances their intrinsic activity and inhibits the formation of the inactive rhombohedral ZnTiO3 phase.