Direct comparison of the reactivity of the non-oxidic phase of Ru(0001) and the RuO2 phase in the Co oxidation reaction

Applying in situ surface X-ray diffraction (SXRD) together with on-line mass spectrometry during the CO oxidation over Ru(0001) allows a direct comparison of the reactivity of the non-oxidic state with that of the RuO2(110) covered surface. This comparison reveals that the RuO2(110) surface is a catalytically active phase at least as active as the non-oxidic phase. At high CO and O-2 pressures of 200 mbar and temperatures above 550 K, the CO oxidation reaction does not proceed isothermally on the RuO2(110) surface. The released reaction heat leads rather to an increase of the sample temperature of up to 130 K accompanied by a self-acceleration of the CO oxidation reaction. (C) 2008 Elsevier B.V. All rights reserved.