MICROWAVE-ASSISTED CATALYTIC COMBUSTION OF DIESEL SOOT

The concept of oxidizing diesel soot in a microwave-assisted catalytic trap was demonstrated. Comparisons were made to experiments using ele ctric heating with and without catalysts to understand the influence o f microwave irradiation on catalysis. The complex permittivities of th e three materials (diesel soot, catalyst and support) involved in such a system were measured and the feasibility of using this combination of materials in diesel soot burn-off was evaluated, based upon these m easured data. It was found that iron and copper were the most active c atalysts in lowering the ignition temperature of diesel soots, while p alladium was a necessary component in achieving more complete combusti on. The iron-containing catalyst was also very effective and energy-ef ficient at low microwave input. A non-thermal or microwave enhancement effect was observed which further decreased the ignition temperature by more than 200 degrees C. It was also found that the more vigorous b urning of diesel soot by microwave heating led to an increase in carbo n monoxide in the combustion products, because of the difference in th e heating mechanism. However, when palladium was used, the same comple teness of combustion as in electric heating could be achieved.