The electron-rich [ZnH]+ species stabilized by titanium silicalite-1 zeolite for propane dehydrogenation

Abstract

Propane dehydrogenation to propylene has broad application prospects, so it is of great significance to explore low-cost and environmentally friendly catalysts. Metal hydrides, as active sites, exhibit excellent dehydrogenation property. Herein, we report titanium modified [ZnH]+ ([ZnH]+···TiO6) site with high activity (14.49 mmolC3H6·gcat−1·h−1) and regeneration performance, which is derived from the in-situ conversion of [ZnOH]+ in the dehydrogenation reaction. Combined with in-situ spectroscopic characterizations and ab initio molecular dynamics (AIMD) simulations, the unique [ZnH]+···TiO6 moiety was confirmed, and the evolution process from [ZnOH]+ to [ZnH]+ was clarified. XPS and AIMD calculations show that Zn in the [ZnH]+···TiO6 structure is in an electron-rich state with high H-affinity, which can effectively reduce the propyl C-H cleavage barriers based on slow-growth simulations. In general, titanium modification can effectively stabilize the [ZnH]+ species and enrich the electrons density of zinc, which contribute to the enhanced PDH performance.