Experimental Study On Removing Mercury From Simulated Flue Gas And Regeneration Of MnO₂/AC

Mereury is a kind of volatile material,as is high physiological toxicity and bioaeeumulation. which in the atmosphere can be spread to the world with the atmospheric circulation, does hazardous pollutant to both human health and environment, and has attracted wide attention in the worldwide. At present, mercury from coal-fired utility boilers is identified as the largest atmospheric mercury emission source. Coal combustion process,mercury heated main form of mercury vapor exist,mainly including elemental mercury (Hg0),two price mercury (Hg2+) and particle-state mercury (Hgp). Because of its volatile and undissolved character, elemental mercury (Hg0) is difficult to be captured with the existing air pollution control devices.Therefore,the favored method for Hg0removal is to oxidize it to its oxidized form (Hg2+) by means of some proper catalysts, many studies have been conducted to to control the mercury emission of coal-fired power plants, especially by solid sorbents with the efficient of Hg0adsorption. The paper is about the development of a new type removal agent for removing mercury in simulated fue gas performance of AC load MnO2.Firstly, the preparation methods of manganese oxide catalysts supported on activated coke (MnO2/AC) are studied, and series of MnO2/AC were synthesized by impregnation and precipitation metnod. How the samples of AC were characterized before and after loading by using TEM、XRD and SEM. The highly dispersed(185.4-468.7m2/g) manganese oxides uniformly distributed on support surface were found.The presence of manganese form was MnO2、Mn2O3and Mn3O4by impregnating,and only MnO2by precipitation.The paper studied Hg0in simulated fule gas removal performance of AC and MnO2/AC on the fixed bed model system. Then discussed of MnO2/AC adsorbent’s Hg0removal performance by many factors such as preparation method, loading value, adsorption reaction temperature, and flue gas component. The physic-chemical behavior of Hg0on the sorbents surface was studied in order to clarify the removal mechanism of Hg0by MnO2/AC.MnO2significantly improved the mercury removal capacity of activated cock after the load in the simulated flue gas, and precipitation adsorbent better prepared precipitation, when the best loading value of MnO2was1%. The simultaneous Hg0removal efficiency increased with the rise of adsorption reaetion temperature(80℃-200℃) which meant chemical adsorption dominated the adsorption proeess. MnO2/AC had good activity on removing Hg0in the presense of O2, when it has been found that SO2inhibited the removal of Hg0, and NO had a certain facilitating role on removal of Hg0. Moreover, in the presence of O2in the flue gas, promotional effects of NO and SO2on the Hg0removal were found, while the presence of H2O inhibited the Hg0removal.To improve the recycling mercury removal efficiency of the MnO2/AC, the characteristic of mercury desorption was investigated during regeneration process in N2atmosphere.The characteristic of mercury desorption on MnO2/AC was relevant to the regeneration temperature and times.