Investigation of catalytic reduction of NO by CO over A- and B- site substituted La(Sr)Fe(Co)O3 perovskites

Abstract

In this study, La1−xSrxFeO3 and LaFe1−xCoxO3 perovskites with different La/Sr and Fe/Co ratios have been synthesized via auto combustion method using glycine as fuel. After complete characterization, the catalytic activity of the perovskites was evaluated in the nitrogen monoxide reduction by carbon monoxide, in a lab-scale plug flow reactor. The most active catalysts were La0.75Sr0.25FeO3 and LaFe0.25Co0.75O3. Substitution in different sites of perovskite structure influences differently the catalytic activity and selectivity. The A-site substitution of La by Sr resulted in decrease of activity due to the presence of strontium carbonate, formed by strong adsorption of the produced carbon dioxide on the catalyst surface while selectivity of the reaction is correlated with the oxygen reverse uptake. The B-site substitution of Fe by Co increases the activity due to the partial -reduction of the classic ABO3 phase to A2BO4 Ruddlesden-Popper perovskite phase La2CoO4.