化学分析分馏过程广泛应用于碱金属及碱土金属对生物质焦炭活性影响的研究。针对化学分析分馏过程对生物质热解焦炭物理化学结构产生的影响展开深入研究。通过压汞仪、扫描电子显微镜(SEM)对化学分析分馏过程中焦炭的孔径分布、孔隙率、比表面积及颗粒表面形貌等物理结构的变化进行了分析,结果表明该过程对焦炭的孔隙率影响显著,对比表面积影响不大,对热解焦炭多孔状表面形貌影响较为突出。利用X射线光电子光谱法(XPS)和拉曼光谱法(Raman)对焦炭表面碳氧活性官能团结构及焦炭芳香环结构等化学结构特征展开了研究,结果表明化学分析分馏过程对生物质焦炭表面碳氧活性官能团结构的破坏作用较小,化学分析分馏对焦炭的芳香环结构影响不大,水洗过程对焦炭内部的交联结构影响不明显,醋酸铵溶液、盐酸对焦炭内部的交联结构破坏明显。
Chemical fractionation analysis is widely used to study the effect of alkali and alkaline earth metal (AAEM) species on the reactivity of biomass char. The influence of chemical fractionation analysis on the physical and chemical structures of biomass char was investigated in this study. The physical structures of biomass char were studied by the mercury porosimetry and scanning electron microscopy (SEM). The results showed that the influence of chemical fractionation analysis on the porosity and surface morphology of the biomass char was apparent. However, the effect of chemical fractionation analysis on the specific surface area of biomass char could be ignored. X-ray photoelectron spectroscopy (XPS) and Raman were used to identify the O-containing functional groups and the aromatic ring structures in the biomass char, respectively. The results indicated that the changes of the oxygen containing functional groups were little during the chemical fractionation analysis. The influence of the chemical fraction analysis on the aromatic ring structures could be ignored. During the chemical fractionation analysis, both NH4Ac and HCl could change the cross-linking structures of biomass char.