用红外光谱表征干酪根和煤的芳碳量

干酪根和煤红外光谱中的芳碳含量常以1600cm~(-1)频带来表征.但该频带的强度受芳碳骨架化学环境和结构的强烈影响.用苯并菲、茬、二羟基蓁、二苯酮和联苄等6种模型化合物进行红外光谱分析发现,1600 cm~(-1)频带因芳环稠化而迅速减弱,因邻接含氧基团而显著增强.对不同类型干酪根的热模拟系列产物进行了红外光谱和固体~(13)C核磁共振波谱的综合研究.结果表明,1600 cm~(-1)的摩尔吸光系数ε_1600有随演化加深而下降的趋势,尤以煤系干酪根为甚,与模型化合物的结果相符.因此,吸收系数K_1600可用以区分干酪根的类型,但不宜用作其成熟度的参数.

CHARACTERIZATION OF AROMATIC CARBON IN KEROGEN AND COAL WITH INFRARED SPECTROSCOPY

Infrared spectroscopy (IR) is one of routine methods for analyzing the characterstics of kerogen and coal structure. In the IR spectra, the band of aromatic carbon stretching absorbance at 1600cm-1 is usually taken as a representation of aromatic carbon content. The measurements and literature data show that there is no definite relationship between the extinction coefficient K 1600 and aromatic carbon content in kerogen or coal. The IR spectra of six selected model compounds reveal that K1600 will be greatly strengthened by using oxygen containing substituents, and be weakened due to the increase of ring condensation. For the type I of kerogen or coal, the molecular extinction coefficient K1600 declines with increasing maturity, while for type I or I of kerogens 1600 rises to a maximum nearby the peak of oil generation, and then drops with evolution going on. This result is consistent with the evolution of aromatic structures in kerogen.