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

Abstract The objective of this work was to prepare La 2 Cu 1− x Fe x O 4 substituted perovskites and to measure their catalytic activity in the CO+NO reaction. Although no real mixed oxide structure was formed, a synergetic effect was observed between copper and iron. The catalytic activity increased by a factor of 3 when the iron content reached 30%, i.e. for the LaCu 0.7 +LaFe 0.3 ternary system. This activity enhancement has been attributed to an increase in the surface concentration of metallic copper which is formed under reaction conditions and can be considered as the main active species in the CO+NO reaction. To improve the activity, La, Cu and/or Fe oxides were prepared onto a MgAl 2 O 4 spinel support in order to increase the number of surface copper sites. A reaction of the MgAl 2 O 4 support with lanthanum to form LaAlO 3 was observed. No Cu/Fe synergetic effect was obtained for LaCu 0.7 +LaFe 0.3 /MgAl 2 O 4 , the most active catalyst being the system La 2 Cu /MgAl 2 O 4 . It seems that for the latter, the support’s effect on the dispersion of copper was the most pronounced.