Abstract

In situ X-ray photoelectron spectroscopy was used to characterise Cu/Mg/Al mixed oxides derived from hydrotalcites (catalyst used for the NO_x removal reaction). The active sites are the copper centres: (i) Cu(0) for NO decomposition and (ii) Cu(0) and/or Cu(I) for NO reduction with a hydrocarbon. The ability of these materials to redisperse the copper active sites without destroying the structure of the material makes them different from other catalysts such as zeolites, and is essential for suitable catalytic behaviour at high temperatures.