Microwave Regeneration of Zeolites in a 1 Meter Column

Although sorption is a common method of removing volatile organic compounds (VOC's) from processes, the adsorbent must be regenerated to repeat the process. The use of microwaves to regenerate the bed of adsorbent can be more efficient than conventional heating methods. Desorption of methanol from a silicalite zeolite was studied by the use of microwaves in cylindrical column. Temperature probes at five axial and three radial positions monitored the temperature profile in time. A significant amount of microwave energy passed through the dry zeolite bed, whereas a strong attenuation occurs if methanol is adsorbed. The radial temperature distribution conforms to theoretical predictions; however, microwave reflections cause a distortion of the predictions in the axial direction. Irregularities during the saturation of the bed indicated a chemical reaction during the it-radiation with microwaves. A fraction of the methanol reacted under microwave irradiation to form dimethylether and water, and to methoxylate the zeolite surface. (C) 2009 American Institute of Chemical Engineers AIChE J, 55: 1906-1913,2009