Formation of Intermetallic Compounds by Reactive MetalSupport Interaction: A Frequently Encountered Phenomenon in Catalysis

This Review discusses the structural and catalytic aspects of the recently introduced reactive metal-support interaction. This special term was coined to account for the inability of the original concept of the strong metal-support interaction to accurately describe the structural, compositional, and electronic changes frequently occurring in oxide-supported metal particle catalysts at very high temperatures upon reduction in hydrogen, in many cases leading to intermetallic compound or substitutional alloy formation. This inaccuracy predominantly refers to the requirement of full reversibility upon oxidation and mild reduction for a strong metal-support interaction. A close look at the formation of oxide-supported intermetallic compounds upon high-temperature reduction reveals that these compounds are very common in catalysis and the situation is much more complex compared to unsupported intermetallic compounds due to the presence of the intermetallic compound-oxide interface.