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

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 Ce_0.5Mn_0.5O₂ catalysts were synthesized using sol-gel method. The effect of K-doped catalysts-K_z-Ce_0.5Mn_0.5O₂-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. K_0.2-Ce_0.5Mn_0.5O₂ showed the best performance among the series of K-doped catalysts. Compared with the findings for Ce_0.5Mn_0.5O₂, the ignition temperature of soot oxidation (T_i) had been lowered by 28 ℃, and the maximum peak combustion temperature (T_m) of the dry soot decreased by 61 °C. Furthermore, compared with the Ce_0.5Mn_0.5O₂-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 K_0.2-Ce_0.5Mn_0.5O₂.