DE-NOX PROCESS IN THE PRESENCE OF CO ON PEROVSKITES LA-NI-O SUPPORTED ON AL2O3 AND ZRO2

The reaction of NO elimination in the presence of equimolecular amount of CO was investigated on lanthanum nickelate Perovskite species supported either on Al2O3 or ZrO2. The support was pretreated with lanthana whose presence was necessary for the development of a LaNiO3 Perovskite phase on alumina. On the contrary the phase developed on the zirconia based solids was La2NiO4. The solids based on alumina possess a specific surface area of 35-65 m2g-1 while those based on zirconia 3-7 m2g-1. The La2NiO4/ ZrO2 solids are more active for the NO elimination as compared to LaNiO3/Al2O3 ones, irrespectively if the activity is calculated per unit mass or unit area of the solids. The smaller activity of LaNiO3/Al2O3 is attributed to the stronger adsorption of NO on the Ni+3 catalytic centers which result in an 25-30% excess conversion of NO as compared to CO. On the La2NiO4/ ZrO2 solids the conversion of NO does not exceeds 12-14% that of CO, the excess of NO in both cases suffering disproportionation towards N2O. The comparison between the behaviour of supported perovskites on ZrO2 with that of the pure solids indicates that ZrO2 acts most probably synergistically in boosting the activity of La2NiO4.