Carbon supported vanadia for multi-pollutants removal from flue gas

Coal combustion generates flue gas that contains many types of pollutants including sulfur dioxide (SO2), nitrogen oxides (mainly NO) and heavy metals (Hg, Pb, As, etc.). Abatement of these pollutants has been an important task for sustainable development of the world, especially of the countries heavily relying on coal as the main primary energy. The dominant flue gas cleaning technologies used worldwide today are effective only for a single pollutant removal at conditions significantly different from each other and from that of flue gas emission. This inevitably leads to high cost for multi-pollutants removal. Research in past decades showed that carbon supported catalysts have superior properties for abatement of many flue gas pollutants, individually or simultaneously, at temperatures of flue gas emission. Among them, activated coke supported vanadia (V2O5/AC) attracted more attention due to its high activities in adsorption and oxidation, which are key properties needed for abatement of these pollutants. This article, as a plenary lecture of the 8th International Symposium on Gas Cleaning at High Temperatures (GCHT-8), is mainly a feature report that summarizes the main research on V2O5/AC catalyst for SO2, NO and Hg removal, especially the contributions made by Chinese researchers. It concentrates on in-depth understanding on surface science and catalysis, including the role of V2O5 in adsorption and oxidation of the pollutants; effects of SO2 and moisture on formation and consumption of poisonous sulfates; the role of AC in adsorption and oxidation of the pollutants and in decomposition of poisonous sulfates; the forms of intermediates and their transformation mechanism; and effects of alkali species in flue gas on activities of SO2 and NO removal.