Efficient Catalysts Based on Substitutional Solid Solutions and Palladium Intermetallic Compounds for the Selective Hydrogenation of Acetylene to Ethylene.

Features of the catalytic action of Pd–Ag, Pd–Cu, Pd–Au, Pd–Ga, and Pd–Zn bimetallic systems on the acetylene conversion to ethylene are discussed taking into account two factors that determine the effect of the second metal on palladium, namely, the "ensemble effect" (geometric effect) and the "ligand effect" (electronic effect). The relationship between the calculated thermodynamic and kinetic parameters of the adsorption interaction of major reaction medium components and intermediates with the catalyst surface, the structure of active ensembles, and characteristics determined in tests, such as the structural parameters of bimetallic phases, the electronic state of their components, and catalytic properties, is shown. Some examples are given to show that the modifier atoms can be incorporated into active ensembles and the sites formed by the modifier atoms can be involved in the catalysis of individual elementary steps. [ABSTRACT FROM AUTHOR]