13C-NMR Study on Structure Evolution Characteristics of High-Organic-Sulfur Coals from Typical Chinese Areas
13C-NMR Study on Structure Evolution Characteristics of High-Organic-Sulfur Coals from Typical Chinese Areas
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DOI：
10.3390/min8020049
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发表时间：
2018-02
期刊：
影响因子：
2.5
通讯作者：
Qiang Wei;Yuegang Tang
中科院分区：
文献类型：
--
作者：
Qiang Wei;Yuegang Tang
利用13 C-CP/MAS NMR研究了中国典型地区不同煤阶高有机硫煤的结构演化特征。结果表明，与煤阶相关的结构参数包括CH 3碳（fal*）、季碳、CH/CH 2碳+季碳（falH）、脂肪碳（falC）、质子化芳香碳（faH）、质子化芳香碳+芳香桥头碳（faH+B）、芳香度（faCP）和芳香碳（farC）。前两次煤化作用跃变，特别是第一次煤化作用跃变，煤的结构发生了剧烈的变化。在烟煤热解初期，大量的芳香结构发生缩合，脂肪结构迅速发展，并伴随着显著的脱羧反应。与普通煤相比，HOS煤的结构演化特征表现在三个方面：第一，芳香CH 3碳、烷基化芳香碳（faS）、芳香桥头碳（faB）和酚醚碳（faP）与煤阶关系不大，丰富的有机硫影响了煤的正常演化过程。第二，部分超高有机硫煤的平均芳香族分子团簇尺寸不大，芳香族分子间交联键和桥键的广泛发育使芳香族分子团簇之间的联系更加紧密。此外，含硫官能团可能是这些连接的重要组成部分。第三，13 C-NMR测定的SHOS煤中的“含氧官能团”中有相当一部分实际上是含硫基团，这导致了煤的含氧结构随煤级的增加而增加的反常现象。
The structure evolution characteristics of high-organic-sulfur (HOS) coals with a wide range of ranks from typical Chinese areas were investigated using 13C-CP/MAS NMR. The results indicate that the structure parameters that are relevant to coal rank include CH3 carbon (fal*), quaternary carbon, CH/CH2 carbon + quaternary carbon (falH), aliphatic carbon (falC), protonated aromatic carbon (faH), protonated aromatic carbon + aromatic bridgehead carbon (faH+B), aromaticity (faCP), and aromatic carbon (farC). The coal structure changed dramatically in the first two coalification jumps, especially the first one. A large number of aromatic structures condensed, and aliphatic structures rapidly developed at the initial stage of bituminous coal accompanied by remarkable decarboxylation. Compared to ordinary coals, the structure evolution characteristics of HOS coals manifest in three ways: First, the aromatic CH3 carbon, alkylated aromatic carbon (faS), aromatic bridgehead carbon (faB), and phenolic ether (faP) are barely relevant to rank, and abundant organic sulfur has an impact on the normal evolution process of coal. Second, the average aromatic cluster sizes of some super-high-organic-sulfur (SHOS) coals are not large, and the extensive development of cross bonds and/or bridged bonds form closer connections among the aromatic fringes. Moreover, sulfur-containing functional groups are probably significant components in these linkages. Third, a considerable portion of “oxygen-containing functional groups” in SHOS coals determined by 13C-NMR are actually sulfur-containing groups, which results in the anomaly that the oxygen-containing structures increase with coal rank.