SO2 poisoning of LaFe0.8Cu0.2O3 perovskite prepared by reactive grinding during NO reduction by C3H6

Abstract

Nanoscale LaFe0.8Cu0.2O3 was prepared by reactive grinding, characterized by XRD, SEM, H2-TPR, O2-, NO + O2-, and C3H6-TPD (with and without SO2), FTIR, tested for catalytic reduction of NO by C3H6 and aged in presence of SO2 to investigate the effect of sulfurous species on its catalytic behavior. Two distinct poisoning mechanisms depending on SO2 feed concentration were thus proposed. At low concentration SO2 (≤20 ppm) can cause a reversible poisoning due to the competitive adsorption of SO2 and reactants as well as the coverage of active sites by surface sulfite and sulfate species. By contrast, 80 ppm SO2 leads to a severe sulfatation with destruction of the perovskite structure and the generation of La2(SO4)3 and Fe2O3 phases resulting in an irreversible loss of activity in NO reduction by C3H6. Partial regeneration of this spent sample can be realized by releasing sulfur from the perovskite under a 5% H2/He atmosphere followed by reconstructing the perovskite structure under an oxygen containing atmosphere.