Activity enhancement of mixed lanthanum-copper-iron-perovskites in the CO plus NO reaction

The objective of this work was to prepare La2Cu1-xFexO4 substituted perovsk ites and to measure their catalytic activity in the CO+NO reaction. Althoug h no real mixed oxide structure was formed, a synergetic effect was observe d between copper and iron. The catalytic activity increased by a factor of 3 when the iron content reached 30%, i.e. for the LaCu0.7+LaFe0.3 ternary s ystem. This activity enhancement has been attributed to an increase in the surface concentration of metallic copper which is formed under reaction con ditions and can be considered as the main active species in the CO+NO react ion. To improve the activity, La, Cu and/or Fe oxides were prepared onto a MgAl2O4 spinel support in order to increase the number of surface copper si tes. A reaction of the MgAl2O4 support with lanthanum to form LaAlO3 was ob served, No Cu/Fe synergetic effect was obtained for LaCu0.7+LaFe0.3/MgAl2O4 , the most active catalyst being the system La2Cu /MgAl2O4. It stems that f or the latter, the support's effect on the dispersion of copper was the mos t pronounced. (C) 2001 Elsevier Science B.V. All rights reserved.