Tracking down the reduction behavior of copper-on-alumina catalysts

The evolution of copper-based catalysts during a reduction treatment has been followed using X-ray absorption near edge structure (XANES) in conjunction with a statistical analysis. Using this novel approach, we will provide evidence of (a) the number and nature of the active copper phases formed during the genesis of the catalysts, (b) their dependence on the chemical conditions of the preparation procedure, (c) the degree of reactivity of these phases toward hydrogen, and (d) details on the mechanism of the solid phase transformations during interaction with this molecule. Transmission electron microscopy (TEM) is used to complement results concerning the nature and physical properties (i.e. particle size) of copper phases, and in order to stress the importance of the XANES findings, conventional temperature programmed reduction (TPR) experiments are compared with a simulation of the hydrogen consumption occurred in the reduction process using the XANES results. (C) 1998 Academic Press.