Interaction of alkali acetates with silica supported PdAu

Abstract

The temperature dependence of the interaction of PdAu alloy particles with alkali acetate promoters (MOAc; M+ = Li+, Na+, K+, Cs+) was studied by X-ray absorption and infrared spectroscopy as well as in situ X-ray diffraction. Alkali acetate promotion on PdAu particles results in irreversible enlargements of the Pd-Pd distances upon heating compared to promoter free PdAu/SiO2. The promoter induces the migration of Pd to the metal particle surface and the formation of a mixed Pd/M+-O layer on the surface of the bimetallic PdAu particles. This structure enhances catalytic reactions by electronically and geometrically modifying the PdAu surface.