Nanoscale Pd/Fe bimetallic particles: Catalytic effects of palladium on hydrodechlorination

Reported herein is a study on the catalytic properties of palladium for hydrodechlorination using nanoscale zero-valent iron particles. Temperature-dependent experiments and X-ray diffraction (XRD) are conducted to characterize reactions of chlorinated ethylenes with nanoscale Fe and Pd/Fe particles. XRD results suggest bimetallic structures are created as a result of Pd(II) reduction by zero-valent iron and the degree of surface palladium loading is proportional to the initial amount of palladium applied. The optimal content of palladium in the bimetallic particles for dechlorination is in the range of 1-5% by weight. XRD analyses further suggest that oxidation of iron produces mainly iron oxides. No oxidized species of palladium (e.g., PdO) is found before or after the reactions. Activation energies of the dechlorination reactions with the nanoscale Pd/Fe and Fe particles are estimated to be 31.1 and 44.9 kJ/mol, respectively. A conceptual model for the catalytic hydrodechlorination by the nanoscale Pd/Fe particles is presented. (C) 2007 Elsevier B.V. All rights reserved.