Study of the surface evolution of nitrogen species on CuO/CeZrO2 catalysts

Abstract

A series of CuO/CZ catalysts with different amounts of copper oxide were synthesized from copper nitrates by incipient wetness impregnation of the ceria-zirconia support. The structural, redox, acidic and adsorption properties were investigated using X-ray diffraction (XRD), BET, H2 temperature programmed reduction (H2-TPR), temperature programmed desorption of NO in the presence of oxygen (NO-TPD) and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The results have shown good catalytic activity for CuO/Ce0,62Zr0,38O2 in NO oxidation to NO2. Species such as nitrites and nitrates were formed on the surface. The transformation of nitrite compounds into nitrate was observed above 200 C. From 300 up to 400 C, decomposition of the surface nitrate to nitrite was discerned. Ammonia was adsorbed on the Lewis and Brønsted acid sites on Cu/CZ catalyst surface during temperature programmed reactions. The evolution of adsorbed NH3 species to NH2 surface group was confirmed by formation specific band of absorption at 1528 cm-1. © 2013 The Author(s).