Synthesis of La-K-Mn-O perovskite-type oxides and their catalytic property for simultaneous removal of NOx and diesel soot particulates

Mixed metal oxides in the La-K-Mn-O system were synthesized and their catalytic properties toward the simultaneous NOx-soot removal reaction were investigated. The solubility limit of K in Lai-xKxMnO3 was determined between 0.2 and 0.25 from X-ray diffraction (XRD) measurement and crystal structure investigation, and K2Mn4O8 was by-produced beyond the solubility limit. The activity and the NO, reduction selectivity depended significantly on the K content, and the oxides with intermediate K contents (x = 0.2 and x = 0.25) or with the composition close to the solubility limit were good catalysts with higher activity and selectivity. The present study revealed that the La-K-Mn-O oxides are good candidates of catalysts for the simultaneous NOx-soot removal reaction. (C) 2001 Elsevier Science B.V. All rights reserved.