氯化亚铬脱除黄铁矿对桦甸油页岩有机质结构的影响

采用元素分析、~(13)C NMR、XPS和TG-MS技术考察了氯化亚铬(CrCl_2)脱除黄铁矿对桦甸油页岩有机质结构的影响。结果表明,CrCl_2可有效脱除有机质中的黄铁矿,脱除率为96.19%。CrCl_2对有机质的碳骨架结构影响较小,脱除黄铁矿前后有机质中脂碳、芳碳和羧基/羰基碳的相对含量以及有机质的热解特征温度基本保持不变,但CrCl_2可破坏有机质中的C-O键,使C-O/C-OH和O=C-O的含量减少,造成0.98%的有机碳损失和12.54%的有机质损失。CrCl_2处理后,有机质的C含量显著增加,H含量稍有增加,O含量显著降低,使得H/C略微降低,O/C明显降低。另外,CrCl_2处理后,单位质量有机质中脂碳的含量增加了5.28%,使其热解过程中产生了更多的挥发分,残留的氧化铬对有机质的热分解可能也具有促进作用。

Effect of pyrite removal by chromous chloride on organic matter structure in Huadian oil shale

Influence of pyrite removal by chromous chloride (CrCl₂) on structure of organic matter in Huadian oil shale was examined using ultimate analysis, ¹³C NMR, XPS and TG-MS technology. The results show that CrCl₂ treatment leads to 96.19% removal of pyrite from oil shale. The relative contents of aliphatic, aromatic, and carboxyl/carbonyl carbons of organic matter remain about the same level after pyrite removal by CrCl₂, so does the pyrolysis characteristic temperature, indicating the carbon skeleton of organic matter is less affected by CrCl₂. However, the CrCl₂ treatment can break C-O bond in organic matter and reduce content of C-O/C-OH and O=C-O, leading to about 0.98% and 12.54% loss for organic carbon and organic matter, respectively. In addition, carbon content of organic matter significantly increases, hydrogen content slightly increases, and oxygen content is markedly reduced after pyrite removal by CrCl₂, resulting in a slight decrease of H/C but a marked decrease of O/C in organic matter. The mass loss of organic matter treated by CrCl₂ increases during pyrolysis because aliphatic carbon content of unit mass of organic matter increases 5.28%. Besides, the residual chromium oxide may also promote decomposition of organic matter during pyrolysis.