Highly Active Monolith Catalysts of LaKCoO3 Perovskite-type Complex Oxide on Alumina-washcoated Diesel Particulate Filter and the Catalytic Performances for the Combustion of Soot

The LaKCoO3/gamma-Al2O3/cordierite and LaCoO3/gamma-Al2O3/cordierite monolithic catalysts were successfully prepared by impregnating the as-pretreated monolith with aqueous solution of metal salts on monolithic cordierite substrate with a dip-coating two-step method. For comparison, one-step method without the alumina sol coating was also investigated. The monolithic catalysts were characterized by means of XRD, FT-IR, BET, ICP, TG-DSC, XPS and SEM-EDS. The characterization results demonstrate the formation of a small amount of Co3O4 when a large amount of K+ was introduced into LaCoO3 for the substitution of La3+. The coating of porous hollow aluminum oxide nano-particles could enhance the surface area of monolithic cordierite by about 100 times. The active components of LaKCoO3/gamma-Al2O3 supported catalysts can disperse on the surface of the catalysts as monolayer and be the uniform distributions of La, Co and K. The ultrasonic vibration treating results indicated that the Al2O3 washcoat and catalyst components were adhered to the substrate strongly, the average weight loss is limited to about 1.0 % of the washcoat weight after 30 min in ultrasonic bath. The TG-DSC results show the good thermal stability of the LaKCoO3 and LaCoO3 coatings on alumina-coated monolithic cordierite. The LaKCoO3/gamma-Al2O3/cordierite catalyst gave the highest catalytic activity for soot combustion among the studied catalysts. The T-10, T-50, T-90 over the LaKCoO3/gamma-Al2O3/cordierite catalyst were 186.3 degrees C, 314.6 degrees C, 390.0 degrees C, respectively, and S-co2(m) was 99.8%.