PHASE-BEHAVIOR OF A PD-CU BIMETALLIC CATALYST DURING TEMPERATURE-PROGRAMMED REDUCTION

The phase behavior of a 1%Pd-0.5%Cu bimetallic catalyst during reducti on has been followed by X-ray absorption near-edge structure (XANES). The analysis of the XANES spectra by Factor Analysis was used to deter mine that after calcination the active components are hosted in three different phases: a Cu-Pd mixed oxide, PdO and Cun+ ions exchanged int o L-zeolite positions. At the Pd K-edge, an intermediate compound is d etected in the reduction process. The reduction of the catalyst yields only one phase, a substitutionally disordered Pd50Cu50 alloy.