Effect of surface area of La-K-Mn-O perovskite catalysts on diesel particulate oxidation

Catalytic combustion of diesel particulate matter (PM) was carried out over K-containing perovskite-type oxide of La_0.8K_0.2MnO₃ (LKM82) with different specific surface areas. The surface area of LKM82 was controlled by changing the preparation methods and conditions. PM combustion temperature evaluated from thermogravimetric analysis decreased by 150 °C and 200 °C under tight-contact and loose-contact conditions, respectively, with an increase in catalyst surface area from 1.1 m² g^-1 to 18.5 m² g^-1. Ceramic foam filters coated with LKM82 catalyst were fabricated to further investigate the PM combustion performance under the practical contact condition between the catalyst and PM. The PM combustion performance was also improved with the increase in the surface area of the catalyst coated on the ceramic foam filter. These findings strongly suggest that surface area is one of the important factors controlling catalytic performance for diesel particulate combustion.