The Study Of Catalysts For Catalytic Oxidation Of Carbon Particulates From Diesel Emission

In this study, the catalysts were prepared by using dipping method for carbon particulate oxidation from diesel soot. Their catalytic properties and structures were also studied at the same time. The effects of V, K, Ca, Ce, Mn, Zr elements in the catalysts were also studied. The catalytic activities of these catalysts were measured with tailor-made equipment.The studies found that the catalysts prepared with the combination of Ca, Ce, Mn, Zr had a poor catalytic activity and the carbon could not be burnt out under 550℃. The catalysts composed of V and K elements can promote carbon oxidation very well, with the carbon ignition point of about 400℃. When adding Ca into V/K-based catalyst, the carbon could be burnt out completely and reduced the iginition point. The catalyst prepared with a composition of V:K:Ca=1:1:0.1 had a carbon iginition point of about 370℃. When Ce was added to V/K-based catalyst, the catalytic activity was also improved and the catalyst prepared with a composition of V:K:Ce=1:2:0.4 had a carbon iginition temperature of about 380℃. The catalyst with a composition of V:Ca:Ce=2:1:0.4 had a carbon ignition point of about 340℃. With increasing the amount of Ca or Ce, the catalytic activity was reduced.XRD tests indicated that the structures of V/K/Ca and V/K/Ce-based catalysts were very complicated. The catalysts composed of V/K/Ca,V/K/Ce may have both amorphous and crystalline phases as demonstrated by XRD and DSC-TG analyses. For both groups of catalysts, there were no V compounds found at lower Ca or Ce content. Therefore, it is very difficult to explain the relationships between the catalyst structures and catalytic actitivties. It was hypothesized that there maybe amporphous V compounds formed and these compounds may play an important role for catalytical oxidation. Other components may also affect the catalyst activity in some extent. In a word, the series of V-based catalysts containing K,Ca,Ce showed a good catalytic oxidation for carbon. There is great potential to prepare the catalysts for carbon particulate oxidation for diesel engine emission control.