| Soot and NOxare the two most important pollutants in diesel exhaust，simultaneous removal of soot and NOxwhich using soot and NOxas reductant andoxidant to each other is the best technical approach. Ru as the catalyst of thisreaction exhibit better catalytic activity. In this paper, Ru series bi-noble catalystsare made by using impregnation method. Their activity of simultaneous removal ofsoot and NOx, and the influence of the preparation conditions of the catalyst andreaction conditions have been studied.Firstly, the activity of Ru-Rh/ZrO2、Ru-Ir/ZrO2、Ru-Pd/ZrO2、Ru-Ag/ZrO2、Ru-Au/ZrO2and Ru-Pt/ZrO2were investigated in oxygen rich condition andoxygen rich containing SO2as well as H2O condition. The results found that inoxygen rich condition, the activity of these catalysts showed some differences,because the kinds of noble metal are not the same. Ru-Rh/ZrO2、 Ru-Ir/ZrO2、Ru-Pd/ZrO2have relatively high activity; In oxygen rich containing SO2as well asH2O condition, activity of the six kinds of Ru series bi-noble catalysts are close,SO2and H2O can promote their catalytic activity.Secondly, due to catalyst preparation conditions will impact the activity ofcatalysts; this paper studied the influence of the load order, load ratio of the noblemetal and the selection of carrier to the activity of catalysts. The results found thatby using step-by-step load method, high ratio of Ru and selecting Al2O3and TiO2as carrier are beneficial for improving catalyst activity.Finally, because of the catalytic reaction conditions of diesel exhaust removalprocess is complex, this paper also study the influence of contact style of catalystand soot, O2, H2O, SO2concentration for the catalytic reaction. The results showedthat Ru series bi-noble catalysts can be maintained good activity in loose contact,improving O2, H2O and SO2concentration can promote the activity of the catalystto si multaneous removal of soot and NOx. However, if the SO2concentration is toolarge, catalyst will be poisoned. |
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