The Catalytic Combustion Of Soot Particles In Diesel Exhaust

Diesel vehicles have received extensive attention because of its high thermal efficiency of fuel economy. However, diesel vehicles exhaust too much amount of soot particles and nitrogen oxides (NOX), especially about soot. The emission of soot and NOX from diesel vehicles play an important role in the total amount of particular matter (PM) and NOx from the vehicles, the emission control of soot and NOx have been drawn great attention.In this paper, CeO2 was doped by different transition metal oxides (Co, Mn and Cu) and alkali metal oxide (K), and the activities of catalysts for the PM oxidation under tight or loose contact condition were investigated. Among them, the K-Mn-Ce oxide catalyst prepared by sol-gel method behaved the highest activity for soot oxidation, especially under loose contact conditions. The ignition temperature of soot oxidation (Ti) was 338℃, and the temperature corresponding to the maximum soot oxidation (Tm) was 405℃。The catalysts were characterized by XRD, BET/TG, H2-TPR, O2-TPD, CO-TPR, FT-IR, C-TPR to study the effects of composition and structure on the activities of the catalysts for soot oxidation. The results suggested that K in the form of nitrate and carbonate was highly dispersed on the catalyst surface. The deposition of K could enhance the redox abilities of catalysts. At the same time, the forming of carbonate species on the surface could improve the contact between the catalyst and the particle.