Study on oxidation activity of Ce–Mn–K composite oxides on diesel soot

Abstract

As an effective method, diesel particulate filter (DPF) technology has a great contribution in reducing soot emissions from diesel engines. To achieve passive regeneration of DPF at low temperatures, K-doped Ce0.5Mn0.5O2 catalysts were synthesized using sol–gel method. The effect of K-doped catalysts-Kz–Ce0.5Mn0.5O2-on the oxidation of soot had been studied by thermogravimetric analysis, and the corresponding catalytic properties were evaluated based on X-ray diffraction (XRD), hydrogen temperature programmed reduction (H2-TPR), O2 temperature programmed desorption (O2-TPD) Raman spectroscopy (Raman), Brunauer–Emmett–Teller (BET) and Fourier-Transform-Infrared (FTIR).The results showed that K doping facilitated the oxidation of diesel particulate matter, which was indicated by the entire mass loss curve shifting to lower temperatures. K0.2–Ce0.5Mn0.5O2 showed the best performance among the series of K-doped catalysts. Compared with the findings for Ce0.5Mn0.5O2, the ignition temperature of soot oxidation (Ti) had been lowered by 28 ℃, and the maximum peak combustion temperature (Tm) of the dry soot decreased by 61 °C. Furthermore, compared with the Ce0.5Mn0.5O2-catalyzed reaction, K doping led to a lower activation energy and significantly improved pre-exponential factor. The minimum reaction activation energy of 27.46 kJ/mol was exhibited by K0.2–Ce0.5Mn0.5O2.