Iron doping boosts the reactivity and stability of the γ-Al2O3 nanosheet supported cobalt catalyst for propane dehydrogenation

Abstract

Supported cobalt catalysts are a promising but immature alternative for the noble metallic platinum and poisonous chromium oxide catalysts widely used in the industrial process of propane dehydrogenation. There is still a large amount of scope to modulate its geometric and electronic structure to optimize its catalytic performance in propane dehydrogenation. In this work, we report that iron doping efficiently promotes the generation of active tetrahedral Co²⁺ species in cobalt tetroxide supported on the γ-Al₂O₃ nanosheet, as disclosed by multiple analytical techniques involving X-ray powder diffraction, UV-vis diffuse reflection spectroscopy, X-ray photoelectron spectroscopy, and hydrogen temperature-programmed reduction. In the propane dehydrogenation reaction, such a system presents an enhancement on the activity and selectivity compared with its cobalt only catalyst counterpart. The optimal loading amounts of cobalt and iron were identified to be 5 wt% and 1.6 wt%, respectively. Structural analysis reveals that a strong interaction of iron with the oxygen ligand weakens the π domination of oxygen into the adjacent cobalt centre, accordingly promoting the catalytic activity and selectivity of cobalt in propane dehydrogenation. An increase in the anti-reductive capability triggered by iron doping evidently improves the durability of such a catalyst in propane dehydrogenation. It's also noted that the surface coordinatively unsaturated Al³⁺ sites of the γ-Al₂O₃ nanosheet synergistically boost the dehydrogenation activity of the cobalt catalyst. This research provides a new strategy for improving the reactivity and stability of the cobalt catalyst in the field of alkane dehydrogenation.