Stabilization of molecular Pd species in a heterogenized wacker-type catalyst for low temperature CO oxidation

Abstract

Heterogenized Wacker-type catalysts that showed high activity in CO oxidation at ambient temperatures were investigated with X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS) techniques. The active palladium and copper species for the carbon-supported Wacker catalyst were determined to be a molecular Pd(II) species coordinated with chlorine ligands and solid Cu2Cl(OH)3 that was formed by interaction between the surface functional groups of the support and the copper precursor. Solid copper phase of Cu2Cl(OH)3 was superior to the traditional CuCl2 · 2H2O for reoxidizing the reduced palladium species in the Wacker chemistry. The chemical environment of copper appeared to have crucial effects on sustaining active Pd(II) species and maintaining high activities in low temperature CO oxidation. © 2000 Elsevier Science B.V. All rights reserved