Comparison between microwave and conventional thermal reactivations of spent activated carbon generated from vinyl acetate synthesis

Microwave and traditional thermal reactivations of activated carbon (AC) used as catalyst support in vinyl acetate synthesis have been investigated. Experiments have been carried out by using a single mode microwave device (MW) operating at 2450 MHz and a conventional electric furnace (CF) under steam and CO2 atmosphere, respectively. The surface properties of the spent AC and the reactivated samples were characterized by means of N2 adsorption and SEM, and compared the effects of different heating mechanisms and activating agents on the adsorption capacities and pore structures of the reactivated AC. These results indicated that the AC obtained by microwave irradiation showed higher adsorption capacities for iodine, methylene blue (MB) and acetate acid, higher BET surface areas and mesoporosity than those obtained by conventional thermal heating. The reactivated samples activated by steam had a narrower and more extensive microporosity as well as higher BET than those activated by carbon dioxide under the same heating equipment. From the results, it was concluded that microwave heating combined with steam as an activating agent could remarkably increase the reactivating efficiency compared to the traditional thermal heating.