Catalytic reduction of nitric oxide over copper Part III: Influence of water vapour

This paper reports on the effect of water vapour on the reduction of NO ove r copper in the presence of oxygen and isobutene. Reactions were studied at 700 K and at 770 K. Mass spectroscopy (MS) and X-ray photoelectron spectro scopy (XPS) were used to monitor the gas phase composition during reaction and to analyse the catalyst surface, respectively. XPS spectra show that th e presence of water vapour influences the Cu oxidation state. At 700 K adso rption of aldehyde is partly blocked by copper oxide resulting in a decreas e in the activity of the reaction, although the main mechanism is not chang ed. At 770 K, water vapour generates an even more oxidised surface, which p romotes a complete oxidation of hydrocarbon, the main mechanism of NO reduc tion is changed, and the activity of the reaction is slightly increased. (C ) 1999 Elsevier Science B.V. All rights reserved.