Hydrogen spillover in nonreducible oxides:Mechanism and catalytic utilization

Hydrogen(H)spillover in nonreducible oxides such as zeolites and Al2O3 has been a highly controversial phenomenon in heterogeneous catalysis.Since industrial catalysts are predominantly prepared using these materials as supports,it is important to understand the mechanism and catalytic functions of H spillover on their surfaces.In the past decade,fundamental studies on zeolite-encapsulated metal catalysts have revealed that H spillover and reverse spillover can be utilized in the design of hydrogenation and dehydrogenation catalysts with improved properties.Both experimental and theoretical studies have indicated that H spillover can occur in nonreducible oxides when they possess substantial acid sites that aid the surface migration of active H.In the present review,we will discuss the possible mechanisms of H spillover in nonreducible oxides and the unique opportunities of using this phenomenon for the design of advanced hydroprocessing catalysts.