Destruction of toxic volatile organic compounds (VOCs) in a microwave-assisted catalyst bed

摘要

Control of VOC emissions from various industrial emission sources in an environmentally acceptable and energy efficient manner has been a constant challenge to the chemical industry. A promising technology for the effective control of such emissions is to use microwave energy to destroy VOCs in a packed bed of microwave absorbing medium. This paper reports preliminary results from an experimental study of VOC destruction using microwave energy. In the study, trace amount of benzene vapor carried by air or nitrogen flowed through an I I mm ID microwave-assisted packed-bed reactor and was destroyed in the reactor by the elevated temperatures generated by microwave irradiation. Granular activated carbon (GAC) and silicon carbide (SiC) foam were used as the packed bed materials as well as the microwave absorption mediums. The inlet and outlet streams were analyzed on-line by GUMS (Gas Chromatography/Mass Spectrometry) and the DRE (Destruction and Removal Efficiency) was determined based on the observed inlet and outlet concentrations of benzene. The experimental parameters also included benzene concentration, packed bed height, carrier gas flow rate, and microwave power level. The current results have indicated that silicon carbide is a better microwave absorption medium than GAC. With silicon carbide being the packed bed medium and air being the carrier gas, the microwave VOC destruction system is capable of achieving a DRE of higher than 99% with low microwave power levels ranging from 200 to 400 watts. The reaction products have been found to be largely CO2, CO, and H2O with only trace amount of other byproducts.