The interaction of hydrogen with alumina-supported copper catalysts: a temperature-programmed adsorption/temperature-programmed desorption/isotopic exchange reaction study

The interaction of hydrogen with a series of copper catalysts (Cu/Al2O3, Cu/ZnO, and Cu/ZnO/Al2O3) was studied by combining temperature-programmed (TP) techniques and the isotopic exchange reaction of H-2 and D-2 with microkinetic modeling. Various TP experiments (TP desorption, TP adsorption) were carried out, resulting in a set of kinetic parameters for a quantitative description. Only small differences in the kinetics of the ZnO-containing Cu catalysts and Cu/Al2O3 were observed, suggesting that the interaction of H-2 with the Cu surface is therefore only slightly influenced by the presence of zinc oxide, and alumina seems to act only as a structural promoter. Significant changes in the results were found when the treatment prior to the actual experiments was altered. From these observations and further supporting experiments it was deduced that a change in the morphology of the metallic Cu particles and surface alloying occur under more severe reducing conditions. These dynamical changes seem to be highly relevant for methanol synthesis. (C) 2003 Elsevier Science (USA). All rights reserved.