准东煤基粉状活性焦对烟气中汞的吸附及再生性能研究

以准东褐煤为原料,在模拟热解气下,通过一维沉降炉分别进行炭化、先炭化后活化(两步法)及同时炭化活化(一步法)制备粉状活性焦。一步法相比于其他两种方法制备活性焦,优势在于系统工艺简单,制备速度快,投资、运行成本低。并针对活性焦对Hg0的吸附能力进行研究,比较了不同制焦的方式对Hg0的吸附性能的影响,考察了在O_2,SO_2和SO_2+O_2气氛下活性焦对Hg0吸附性能,进一步探索了乏焦的高温、微波解吸及对Hg0的二次吸附规律。结果表明:一步法获得的活性焦样品具有大的比表面积、微孔比表面积和丰富的C■O官能团,因此等量的活性焦对Hg0的吸附性能优于炭化、两步法,其3 h的吸附量分别为6. 53,3. 62和5. 41μg/g; O2提供活性焦表面上活性氧位,进而促进Hg0在活性焦表面吸附,SO_2抑制Hg0的吸附,主要因为SO_2与Hg0在活性焦上发生竞争吸附,但是SO_2与O_2同时存在时,在活性焦上进一步形成具有强氧化性的SO42-,促进Hg0的化学吸附;微波下,15 min内吸Hg0活性焦解吸完全,其解吸速率大于高温解吸速率,高温、微波解吸后的活性焦进行二次吸附,微波解吸后其吸附量大于高温解吸后的活性焦,其3 h的吸附量分别为5. 962和7. 280μg/g,说明微波对活性焦再生具有促进的作用,其原因是在微波解吸过程对活性焦具有再活化和促进微孔生成。

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 simulated 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 Hg0,further,the effects of O2,SO2 and SO2+O2 on Hg0 removal efficiency were examined in flue gas.Besides,the desorption of Hg0 was explored and the regeneration experiments conducted under microwave and thermal methods were investigated.The results indicate that the active coke prepared by the one-step method has a large specific surface area,microporous specific surface area and abundant C〖CDS1〗O functional groups,thus has a better Hg0 removal efficiency than that of the other two methods,and the adsorption capacity was 6.53,3.62 and 5.41 μg/g in 3 h,respectively.The O2 provided reactive oxygen sites on the surface of the active coke,promoting the adsorption of Hg0 on the surface of the active coke.However,the SO2 exhibited effect on Hg0 removal due to the competitive adsorption between the SO2 and Hg0 on the active coke.Interestingly,the SO2-4 with strong oxidation ability would be formed when the O2 and SO2 were injected into the reactor simultaneously,which greatly promoted the chemical adsorption of Hg0.Furthermore,the spent active coke was desorption completely within 15 min by microwave,and its desorption rate was higher than that in high temperature 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 microwave could reactivate the active coke and promote the formation of micropores in the microwave desorption process.