J. Phys. Colloques
Volume 47, Numéro C8, Décembre 1986EXAFS and Near Edge Structure IV
|Page(s)||C8-289 - C8-292|
J. Phys. Colloques 47 (1986) C8-289-C8-292
XANES/EXAFS STUDY OF THE COPPER ACTIVE SITE IN METHANOL SYNTHESIS CATALYSTL.S. KAU, E.I. SOLOMON et K.O. HODGSON
Department of Chemistry, Stanford University, Stanford, CA 94305, U.S.A.
We have used X-ray absorption spectroscopy to determine the electronic and geometric structure of the copper active site in methanol synthesis catalysts. Compared to the edge and FT of the EXAFS data of CuO, the data suggest that most of the Cu(II) in the calcined form does not have the same ligation as in the CuO lattice and more importantly that some of the Cu is dissolved in the ZnO lattice. For the reduced sample, the edge shifts to lower energy after reduction, indicating the presence of either Cu(I) or Cu(0). The EXAFS data analyses of reduced catalysts show the presence of copper clusters. Reaction with H2S is shown to decompose the Cu clusters in the reduced catalyst and the level of Cu cluster decomposition increases with further reaction at higher temperature and longer time period.