Non-oxidative propane dehydrogenation over Co/Ti-ZSM-5 catalysts: Ti species-tuned Co state and surface acidity

With the modified Ti-ZSM-5 zeolites as supports, the propane dehydrogenation (PDH) performance of the non-noble metal Co-based catalysts can be enhanced, which is benefited from the Ti species-tuned state of active Co species and surface acid property. The developed Co/Ti-ZSM-5 catalysts exhibit >95% C3H6 selectivity and good regeneration stability in the recycling PDH reactions. The characterization results illustrate the structural evolution of Ti from the framework and extra-framework Ti species to the small-size anatase TiO2 species with decreasing the Si/Ti ratio of the Ti-ZSM-5 zeolites, tailoring the dispersion and chemical state of the Co sites at different Co-zeolite or Co-TiO2 interfaces. The Ti-ZSM-5 zeolites with high Si/Ti ratios also show significantly reduced surface acidity especially the Brønsted acidity in comparison with the Al-ZSM-5 zeolite, thus facilitating the C3H6 desorption for enhancing the selectivity and anti-coke stability.