低中煤级煤结构演化的FTIR表征

通过对28个最大镜质组反射率0.295%-2.047%镜煤样品的FT-IR分析，获得低中煤级煤结构的演化规律及机理。研究表明：煤化学结构主要由芳香结构、脂族结构和含氧官能团组成。煤的结构演化分为三个阶段，分别是镜质组反射率小于0.8%、0.8-1.3%和1.3-2.0%。在镜质组反射率小于0.8%阶段，以含氧官能团的脱落和脂肪类物质的富集为主；在镜质组反射率0.8-1.3%阶段，则主要是脂肪类物质的富集和支链化程度的增加或脂环化作用与芳香化作用的协同；在镜质组反射率1.3-2.0%阶段，则在镜质组反射率小于1.7%前，主要为脂肪类物质的热解断裂，而之后，则是随着脂肪类物质的断裂脱落，形成新的芳香结构体系。低中煤级阶段煤结构的演化特征与第一、二次煤化作用跃变的发生密切相关。

FTIR characterization of structural evolution in low-middle rank coals

FTIR spectroscopic analysis for 28 different rank coals (0.295% to 2.047% of Ro,max) showed structural evolution characteristics and mechanism in low-middle rank coals. The results showed that the chemical structure of coal is consist of aromatic structure, aliphatic structure and oxygen functional groups. Three stages of coal structure evolution are <0.8%，0.8-1.3% and 1.3-2.0% of Ro,max. In the stage of Ro,max <0.8% , The dominant characteristic is oxygen functional group loss and aliphatic material enrichment; in the stage of 0.8-1.3% ( Ro,max), aliphatic material and branched chain increase or synergy of aliphatic cyclization and aromatization is primary; in the stage of 1.3-2.0% ( Ro,max), characteristics are mainly pyrolysis cracking of aliphatic material (Ro,max= 1.3-1.7%) and new aromatic structure system formation with decreasing of aliphatic material (Ro,max= 1.7-2.0%), respectively. The 1st and 2nd coalification jumps are closely related to structural evolution characterization of the low-middle rank coals.