Explore the adsorption and regeneration properties of Zhundong powder coke on mercury

The powder coke was obtained by three methods:carbonization,carbonization followed by activation ( two- step method) and simultaneous carbonization activation (one-step method),respectively,under the condition of simu- lated coal-fired hot gas in a drop-tube reactor. The biggest advantage of using the one-step method was that it can greatly simplify the process,and the investment were significantly reduced comparing with the other two methods. The active cokes obtained by three different methods were used to explore the adsorption property of Hg0 , further, the effects of O2 ,SO2 and SO2 +O2 on Hg0 removal efficiency were examined in flue gas. Besides,the desorption of Hg0 was explored and the regeneration experiments conducted under microwave and thermal methods were investigated. The re- sults indicate that the active coke prepared by the one-step method has a large specific surface area,microporous spe- cific surface area and abundant C O functional groups,thus has a better Hg0 removal efficiency than that of the oth- er two methods,and the adsorption capacity was 6. 53,3. 62 and 5. 41 μg / g in 3 h,respectively. The O2 provided reac- tive oxygen sites on the surface of the active coke,promoting the adsorption of Hg0 on the surface of the active coke. However,the SO2 exhibited effect on Hg0 removal due to the competitive adsorption between the SO2 and Hg0 on the active coke. Interestingly,the SO24- with strong oxidation ability would be formed when the O2 and SO2 were injected in- to the reactor simultaneously,which greatly promoted the chemical adsorption of Hg0 . Furthermore,the spent active coke was desorption completely within 15 min by microwave,and its desorption rate was higher than that in high tem- perature condition. Secondary adsorption for the active coke was performed after the high temperature and microwave desorption,and the adsorption capacity after microwave desorption was remarkably improved comparing with thermal methods,where the adsorption amounts of 5. 962 and 7. 280 μg / g in 3 h were achieved. The reason was that micro- wave could reactivate the active coke and promote the formation of micropores in the microwave desorption process.