화학공학소재연구정보센터
Applied Catalysis B: Environmental, Vol.93, No.3-4, 304-313, 2010
Effect of Fe/Co-ratio on the phase composition of Pd-integrated perovskites and its H-2-SCR of NOx performance
La-based perovskites doped with palladium were synthesized by a modified citrate route and calcined at high temperature. The Fe/Co-ratio at the B-site of the perovskite (LaFe0.95-xCoxPd0.05O3, x = 0.475, 0.4, 0.3) was intentionally varied in order to produce a single phase catalyst and to correlate the phase(s) variations with its catalytic performance during the H-2-SCR of NOx. A mixture of crystal phases containing orthorhombic and cubic perovskites, cobalt oxide and strongly bonded palladium oxide were observed in the sample with Fe/Co = 1. Single orthorhombic perovskite phase with traces of iron oxide and weak bonded palladium oxide was obtained with Fe/Co approximate to 2.2. The perovskite with Fe/Co = 1 displayed better NOx reductions and N-2-selectivities than the perovskite with Fe/Co = 2.2 ratio during dry H-2-SCR of NOx. The same was observed with H2O + CO2 and in the presence of CO in the feed. The observed catalytic behaviour of both perovskites is discussed in association with the state of palladium in each investigated composition since the Pd-free perovskite displayed an extremely low NOx-reduction (below 4%). (C) 2009 Elsevier B.V. All rights reserved.