循环脱硫再生过程中活性焦表面性质和孔结构的演变规律

利用固定床反应系统模拟活性焦烟气脱硫及再生过程，进行了10次循环的脱硫再生实验，测定、计算了活性焦硫容；借助XPS和SEM表征再生前后活性焦的表面化学及形貌，测定了活性焦77 K下N2的吸附/解吸等温线，并解析获得了活性焦的BET比表面积和孔容。结果表明，循环脱硫再生过程中活性焦的比表面积和孔容呈上升趋势，分别由312.3 m2/g和0.147 9 cm3/g增加至441.4 m2/g 和 0.203 0 cm3/g，与此同时表面O元素含量由15.63%逐渐增加至19.09%；随着孔容、比表面积、表面O含量的增加，活性焦的硫容由最初的101.29 mg/g 下降至22.56 mg/g，前6个循环活性焦硫容与其表面O含量呈逆向相关关系。表面酸性的增强抑制了SO2在活性焦催化活性位的化学吸附，导致脱硫性能降低。

Evolution of pore structure and surface characteristics of activated coke during circulations of desulfurization and regeneration

The experiments of desulfurization-regeneration (D-R) with commercial activated coke on a fixed-bed reactor in the simulated flue gas were conducted for ten cycles.The desulfurization capability of the activated coke was determined and calculated.Surface chemistry and morphology of the activated coke before and after regeneration were characterized by XPS (X-ray Photoelectron Spectroscopy) and SEM (Scanning Electronic Microscopy),respectively.Adsorption/desorption isotherm of nitrogen at 77 K of the activated coke was plotted,and thus the BET specific area and pore volume of the activated coke were obtained.Results show that with the proceeding of D-R cycle the BET specific area and pore volume of the activated coke are on a rising trend,increasing from 312.3 to 441.4 m2/g and from 0.147 9 to 0.203 0 cm3/g,respectively,meanwhile a gradual increase of oxygen content from 15.63% to 19.09% on surface of the activated coke can be observed;an unfavorable decrease of the desulfurization capability from 101.29 to 22.56 mg/g accompanied the increase of pore volume,BET specific area and surface oxygen content.During the first six D-R cycles there is an inverse relationship between the desulfurization capabilities and surface oxygen content on the surface of the activated coke.It is the enhancement of acidity of surface that inhabits SO2 chemisorptions on the active sites,which results in the progressive loss of desulfurization ability.