O. P. Tkachenkoa, c), K. V. Klementieva, d), N. Koca, e), X. Yua, M. Bandyopadhyay b),

S. Grabowskib, H. Gies b), W. Grünert a)



a) Lehrstuhl für Technische Chemie, Ruhr-Universität Bochum, D-44780 Bochum, Germany (, b) Lehrstuhl für Kristallographie, Ruhr-Universität Bochum, D-44780 Bochum, Germany, c) N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sci­ences, Moscow, Russia,  d) Hasylab, Hamburg, Germany, e Department of Chemical Engineering, Istanbul University, 34850 Istanbul, Turkey





The reduction of copper oxide species dispersed in microporous and mesoporous matrices has been studied by TPR, XPS/XAES, and XAFS. While the reduction of bulk CuO and of Cu(II) in mesoporous MCM-48 (5.6 wt-%) proceeded in one step without intermediate Cu(I) being detectable under the experimental condi­tions, Cu(II) in microporous matrices was reduced in two steps. The two-step scheme cannot be identi­fied with the reduction steps Cu(II) ® Cu(I) and Cu(I) ® Cu(0). Instead, highly disperse Cu(0) may be present al­ready after the first reduction step. In siliceous matrices, coexistence of Cu(0), and Cu ions was ob­served over a wide temperature range, obviously due to the absence of an autocatalytic re­duction process. The latter occurred in Cu-ZSM-5, apparently involving simultaneous segregation of Cu metal from the matrix. This suggests that very small (oligomeric) Cu metal clusters are unable to activate hydrogen. The reduction be­haviour of Cu in Y zeolite depends critically on the thermal history of the sample due to the population of hidden sites by copper upon calcination. Highly disperse Cu particles are stable in MCM-48 up to 500 °C.



Proceedings: 14th International Zeolite Conference, 25-30 April 2004-05-13

Editors: E. van Steen et al                                            

ISBN: 0-958-46636-X
Cape Town, South Africa
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