Experimental Study On Microwave Regeneration Of Activated Carbons Loaded With SO₂

Flue Gas Desulfurization (FGD) by activated carbon is an efficient, widely applied recycling technology that can not only remove pollutant from flue gas, but also recover the sulfur resource. And activated carbon regeneration is critical step. In recent years microwave heating has been the research focus of regeneration because of integrity, selectivity and high efficiency. Recently microwave regeneration of activated carbons load with SO2mainly concentrates on the physical adsorption. But chemical adsorption occurs in most flue gas and H2SO4from catalytic oxidation of SO2is adsorbed in activated carbons pore volume. The research of microwave regeneration of activated carbons by chemical adsorption has not start. Combining microwave regeneration experimental system with fix bed adsorption system, this dissertation focused on the research of regeneration progress and mechanism in microwave field of activated carbons by chemical adsorption and getting the operating conditions applying to the regeneration in order to provide data base and theory reference for industrial applications of microwave regeneration.Firstly, this dissertation studied the microwave heating characteristics of activated carbons. The results show that activated carbons heats up quickly under microwave radiation and stable temperature rises with the increasing of microwave power. The gas species of activated carbons in microwave radiation mainly include CO and CO2. Microwave radiation makes specific area, pore volume and average pore size of activated carbons increase and content of O decrease. And microwave radiation makes acidic surface functional groups decrease and alkaline functional groups increase. The adsorption properties of activated carbons drop after100W and200W microwave radiation and rise after300W and400W microwave radiation. Specific area has less influence to the adsorption properties. Alkaline surface functional groups and the active sites produced by dissociation of oxygen-containing groups have great influence on the adsorption properties. Secondly, microwave regeneration of activated carbons was studied. The results show that, microwave regeneration products of activated carbons loaded with SO2mainly include SO2, CO2and CO. The time to concentration peak of SO2is less than2min and most SO2has been desorption in6min. Microwave regeneration is quick and could obtain high concentration gas products and save inert gas.Finally, adsorption-regeneration cycles was studied to investigate the cycles’ influence of the adsorption properties, surface properties and quality loss of activated carbons. The results show that microwave regeneration is an effective method to the regeneration of activated carbons. After the first regeneration the adsorption properties in different microwave power except100W power improve compared with original activated carbons. And adsorption capacity increases with the power increases. H2SO4in carbons’pore with not completely dissociation blocks the adsorption properties of activated carbons. Acidic surface functional groups mostly decompose and the amount of the alkaline surface functional groups increases in200W,300W and400W microwave radiation power, so the adsorption properties increase. Adsorption properties are still high after several adsorption-regeneration cycles in suitable microwave regeneration power and better than original carbons after17cycles. Regenerative response has activation function and makes the pore long and narrow. Besides, microporous specific surface area and pore volume increase and acidic and alkaline surface functional groups keep stable, so adsorption capacity increases. The weight loss exists because of the chemical reaction between C and H2SO4. The weight loss is19%in300W power and27.8%in400W power after17cycles.