低熟煤型气的成因化学

用水介质热压模拟、_１３Ｃｎｍｒ分析表明，Ｒｏ＝０.７%以前，煤型有机质中的芳环结构的变化主要是官能团的变化，芳环仍然保留着单环的结构特征，并未发生明显的缩合作用。即在早期热演化过程中由邻甲氧基苯酚结构向邻苯二酚类结构转化，进而转化为烷基酚类结构，同时脱去甲氧基中的甲基。甲氧基含量从Ｒｏ＜０.３%开始迅速减少，到Ｒｏ＝０.７%时已基本脱除完毕。煤型有机质中的甲氧基在热演化早期通过自由基反应脱去甲基，对低熟煤型气有重要贡献。

Formation Chemistry of the Fmmature coal gas

The Fanzhi brown coal (R°% 0. 28) was subjected to hydrous pyrolysis. The brown coal and solidpyrolyer residues (R°% 0.32y-0.68) were studied by 13 Cnmr. The Shulan(R°% 0.32) and Huangxianbrown coal(R°% 0. 68) were also analyzed by 13C nmr. The results indicated that progressive changesin the chemistry of early coal evolution are likely.(1) demethylation of guaiacyl units to form catechollike structures that are dominant components of the brown coal,(2) cleavage of aryl ether linkages toform phenols and reactive carbocations that alkylate the catechol rings and(3) dehydration of the cate-chol-like structuens to form alkyl phenols. Aromatic ring substitution index(σ)was nearly constant inthe early evolution. The results suggested that aromatic ring in ligin structure did not fuse to form pol-yaromatic rings beforeR°% 0. 7 and CH₄was one of the main products in the early coalification process.