Studies on SO2 Tolerance and Regeneration over Perovskite-Type LaCo1–xPtxO3 in NOx Storage and Reduction

Abstract

A series of perovskite-type LaCo1–xPtxO3 (x = 0, 0.05, 0.08, and 0.10) were synthesized by the sol–gel method and well characterized by XRD, N2 physisorption, H2-TPR, TEM, and XPS. NOx storage and reduction (NSR) performances of LaCo1–xPtxO3 were initially evaluated using NO-to-NO2 conversion, NOx storage capacity, and NOx conversion. The results demonstrate that NSR performances of Pt-substituted perovskites are higher than that of LaCoO3, and LaCo0.92Pt0.08O3 possesses the best NSR properties with NOx conversion of ca. 90% at 350 °C. Moreover, LaCo0.92Pt0.08O3 exhibits higher resistance to SO2 poisoning and better regenerability than 1 wt % Pt/16 wt % Ba/Al2O3 in NSR. No obvious deactivation is observed after LaCo0.92Pt0.08O3 has been treated at 850 °C for 40 h and subjected to NOx reduction at 350 °C for 200 h; the perovskite structure is well maintained in the process. The addition of 10 vol % H2O lowers NOx conversion to about 77%, but the removal of water from the reaction gas immediately raises NOx conversion to 90%.