A New Approach to Well-Defined, Stable and Site-Isolated Catalysts

A new concept to circumvent some of the problems that are hindering a rational metallic catalyst development is introduced. Investigation of conventional metal catalysts – which consist of supported metals, metal mixtures or alloys – is handicapped by the presence of a variety of active sites, their possible agglomeration, metal-support interactions as well as segregation of the components. In order to avoid most of the drawbacks we employ well defined, ordered and in-situ stable unsupported intermetallic compounds. The knowledge of the chemical bonding in the compounds and the defined neighbourhood of the active sites allow a rational approach to catalysts with excellent selectivity as well as long-term stability. The concept is demonstrated for the intermetallic compound PdGa which is applied as catalyst for the selective hydrogenation of acetylene to ethylene.