ACTIVATION PROCESS OF CUY ZEOLITE CATALYST OBSERVED BY TPR AND EXAFS MEASUREMENTS

EXAFS measurements have been employed to investigate structural changes of Cu species in Y-zeolite during TPR process. The formation of an active species by a consecutive reduction-reoxidation treatment was clearly demonstrated in the TPR spectra. Detailed analysis of the EXAFS data suggested that at a considerably low temperature the active species was reduced directly to Cu metal with a particle size of 5-8 Å, while at higher temperatures the original Cu2+ ions were reduced by a two-step mechanism, via Cu+ ions to Cu metal. From these points of view, the active species is considered to be small clusters of CuO with several Cu atoms.