活性焦孔结构及表面性质对脱除烟气中SO_2的影响

Effects of Micropore Structure and Surface Properties on the SO_2 Removal in Flue Gas by Active Coke

对两种不同方法得到的比表面积相近但脱硫性能差别甚大的活性焦,进行了孔结构、表面化学特性的表征,并进行了脱硫性能的测试.结果表明,活性焦的脱硫性能与其比表面积的关系不大,孔径分布对其存在一定的影响,而活性焦的表面化学特性(表面官能团的种类和浓度)对脱硫性能有很大的影响,在实验分析得到的C—C、C—O、CO、COOH及π—π 5种官能团中,羰基官能团(CO)和醚基官能团(C—O)的总浓度的大小与活性焦的脱硫性能表现出极大的相关性,这两种官能团的浓度越高,活性焦的脱硫性能越强,并对应较大的苯甲酸吸附值,因此可以推断这两种官能团对活性焦的表面碱性起了主要的贡献,并且决定着活性焦脱硫活性的大小.

Two active cokes with similar specific surface area but from different origins were used to remove SO2 in simulated flue gas. The active cokes were characterized by N2 adsorption at 77 K, and analyzed by BET equation to obtain BET surface area, by t-plot method to obtain micropore volume and micropore area, by Horvath-Kawazoe equation and Dubinin-Astakhov equation to obtain micropore distribution from different profiles, and by density functional theory to get pore size distribution. The surface functional groups were determined by X-ray photoelectron spectroscopy and the surface basicity is detected by the adsorption of benzoic acid. The results show that there is almost no connection between the desulphurization activity of the active cokes and their BET surface areas, pore volume, but certain relationship exists between the pore size and the pore size distribution. Within the five kinds of functional groups detected, the density of ether and carbonyl exhibits the consistence with the desulphurization activity and is correlated with values of the adsorption of benzoic acid. It can be concluded that the surface basicity is mainly related to the ether and carbonyl functional groups and determines the capacity of carbon sorbent.