Microwave-induced combustion of volatile organic compounds in an industrial flue gas over the magnetite fixed-bed

A modified domestic microwave oven was applied to heat a magnetite (Fe₃O₄) fixed-bed for continuous decomposition of volatile organic compounds (VOCs), such as acetone, n-hexane, and dichloromethane (DCM), in a simulated flue gas which contains VOCs equivalent to 2000 ppmv as DCM. Experimental results revealed that effect of the addition of water to the inlet stream on decomposition of DCM in the overall experiment was insignificant. Bulk temperature of the Fe₃O₄ fixed-bed was also found to reach 600 °C from an initial room temperature by 6.5 min under microwave radiation, even though the inlet gas was at a high gas hourly space velocity of 5240 h⁻¹ and a high relative humidity of 75%. Moreover, the VOCs in the inlet stream could be decomposed completely over the Fe₃O₄ fixed-bed by microwave heating at a power level of 645 W at heating time of 10 min. The conversion of VOCs is stable when the Fe₃O₄ fixed-bed has been heated longer than 10 min with microwave radiation. The microwave-induced heating upon Fe₃O₄ fixed-bed processing appears to be not only an energy efficient technique for air pollutions treatment but also a promising technology for variety of VOCs in a flue gas from industrial factory being decomposed simultaneously and completely.