Study of Ce, Ca, Fe, and Mn-Doped LaCoO Perovskite Oxide for the Four-Way Purification of PM, NO, CO, and HC from Diesel Engine Exhaust.

Perovskite-type catalysts were widely used in the field of automobile exhaust purification due to their inherent physicochemical properties and excellent doping characteristics. A series of LaMCoNO (M = Ce, Ca; N = Fe, Mn) perovskite-type catalyst samples were prepared by sol-gel method for the four-way purification of PM, NO, CO, and HC emitted by diesel exhaust. The activity of catalyst samples was tested by simulation experiments and hydrogen temperature-programmed reduction (H-TPR). Catalyst samples were characterized by means of XRD, FT-IR, SEM, BET, and XPS analysis. The results demonstrated that the perovskite-type catalyst samples with a particle pore size of 3-5 μm can be prepared by sol-gel method. When A-site of LaCoO perovskite-type oxide was doped by cerium ions, the catalyst samples produced small distortion. The doping of cerium ions to A-site was more conducive to the four-way purification of diesel exhaust than calcium ions. LaCeCoO perovskite-type samples showed the best purification efficiency, and the purification efficiencies of PM, NO, CO, and HC were 90%, 85%, 94%, and 100%, respectively. When the B-site of LaCeCoO perovskite was doped with iron ions, the purification efficiency of catalyst samples for PM and NO can be further enhanced. When the B-site of LaCeCoO perovskite was doped with manganese ions, the purification efficiency of the catalyst samples for PM can be further enhanced. It can be seen from the simulation experiments that LaCeCoFeO perovskite was the best doping amount, and the purification efficiencies of PM, NO, CO, and HC were 95%, 92%, 94%, and 100%, respectively.