Catalytic combustion of soot deposits from diesel engines

Abstract

The catalytic combustion of diesel soot under the influence of metal oxides and metals has been studied. The catalytically active materials, dispersed on a carrier of γ-alumina, have been studied in order to simulate the conditions in a catalytic particulate trap. A mixture of soot and catalyst was placed in a flow reactor and a gas mixture containing 6% oxygen, 7% water and balance of nitrogen was led through it at a flow-rate of 90 l/h. The combustion rate was determined between 573 and 698 K. The results showed that V 2O 5 is the most active catalyst for the combustion of diesel soot whereas oxides of copper, manganese and chromium as well as the metals silver and platinum are active in the combustion of hydrocarbons that desorb from the diesel soot upon heating. Catalytically active materials sensitive to sulphur poisoning are deactivated immediately during the experiments as large amounts of SO 2 are released from the diesel soot when heated. The results indicate that V 2O 5 is not sensitive to sulphur poisoning. This study shows that a catalyst for the combustion of diesel soot should be based on V 2O 5.