Microenvironment engineering of non-noble metal alloy for selective propane dehydrogenation

Abstract

Although non-noble metal catalysts are appealing for propane dehydrogenation, achieving high propylene selectivity remains a persistent challenge, which necessitates the regulation of catalytic microenvironment. In this study, we comparatively investigate three commonly used active metals (Pt, Pd, and non-noble metal Ni) using both theoretical and experimental approaches. We find that the low selectivity of Ni-based catalysts is intrinsically attributed to a narrow interatomic distance (Δd) between Ni atoms, which promotes side reactions. Thus, Ni-based intermetallic alloys are employed to modulate Δd, whose surface microenvironment is quantified with a descriptor called degree-of-isolation. The established volcano-shaped isolation-selectivity plot provides a direct avenue for predicting propylene selectivity, which is determined by two competing variables: desorption and further dehydrogenation of propylene. The optimal catalyst, NiIn, manifests moderate Ni–C repulsion, obtaining >91% experimental propylene selectivity. This reveals the Sabatier principle over Ni-based catalysts for selective propane dehydrogenation and underscores the significance of microenvironment engineering.