Catalytic Characteristics of Component Elements in Heusler Alloys for Hydrogenation of Propyne

Abstract

Intermetallic compounds can be novel catalysts due to their unique structures consisting of multiple elements that occupy specific atomic sites. Heusler alloys (X₂YZ) are a ternary intermetallic group consisting of various sets of X, Y, and Z. This group is useful in investigating the catalytic roles of individual elements under the same crystal structure. In this study, we investigated the catalytic characteristics of 3d transition metals and the group 13,14 elements in Heusler alloys for hydrogenation of propyne (C₃H₄). A larger number of valence electrons for 3d transition metals seemed to result in higher activity for the hydrogenation reaction, as well as pure metal catalysts, the activity hierarchy of which was Ni > Co > Fe. For the group 13,14 elements, the alloys with Al and Si were slightly active, whereas the ones with Ga and Ge were active, in which the Ge alloys were highly selective for producing propylene (C₃H₆). All the Sn-containing alloys significantly caused side reactions producing C₄ and C₆ species. This indicates that Sn possesses the ability to crack and couple carbon chains.