SURFACE-REACTIONS OF MOLECULAR-HYDROGEN ON GAS-PHASE DEPOSITED MAGNESIUM-OXIDE

MgO samples with a specific surface area of up to 400 m2/g were prepar ed by chemical gas phase-deposition. The resulting samples were used f or H-2 and D2 chemisorption experiments. IR spectroscopy clearly evide nces that homolytic and heterolytic dissociation processes are effecti ve. The corresponding surface centers are radicals (O- and Mg+) and io n pairs Mg3C2+O3C2-, respectively. In addition, two isotope exchange r eactions on completely different time scales occur between D2 and isol ated surface OH groups.