活性炭纤维脱除烟气中气态汞的试验研究

Characteristics of the Mercury Vapor Removal From Flue Gas by Activated Carbon Fibers

选用活性炭纤维样品ACF-1,分别进行了浓硝酸湿氧化、部分脱附和空气氧化处理,获得样品ACF-N、ACF-N-D和ACF-A。对ACFs样品进行了表面特性的表征,包括氮分子吸附(77.4K)和X射线光电子能谱分析。以ACFs为吸附剂分别在氮气气氛和模拟烟气组分2种条件下,进行了气态Hg0吸附实验。改性后的ACFs其吸附性能均得到不同程度提升。从ACF孔径分布、表面含氧官能团的种类及数量考察其与ACFs吸附活性之间的关系。由于C=O、COOH基团具有较强氧化性,可作为氧化吸附汞的活化中心;而ACF表面的微孔结构可能作为接收电子的电极参与到Hg0的氧化过程中。因此,微孔容积的增加,ACF表面C=O和COOH含量增加,都将有助于提高ACF的汞吸附能力。

The raw activated carbon fibers （ACF-1） sample were treated with HNO3 acid digestion,partially desorption,and air oxidation.The resulting materials were respectively termed ACF-N,ACF-N-D and ACF-A.The characterization of surface properties of ACFs was conducted by nitrogen adsorption at 77.4 K and X-ray photoelectron spectroscopy （XPS）.Vapor phase mercury adsorption experiments were carried out at nitrogen or simulated gas in a fixed-bed reactor.ACFs after chemically treated exhibited the different levels promotion of mercury adsorption capacities.The capacity can be correlated with pore volume and surface functional groups of ACFs.Oxygen functional groups such as carbonyl and carboxyl groups with strong oxidizability are the possible sites for mercury capture.Micro-pore volume of ACFs surface possibly acts as an electrode to accept electrons for mercury oxidation process.Therefore both increase in the amount of micro-pore volume and the content of surface functional groups （C=O,COOH） on ACFs,are important properties for improving the performance of mercury removal from flue gases.