The generation of benzene carboxylic acids from lignite and the change in structural characteristics of the lignite during oxidation
The generation of benzene carboxylic acids from lignite and the change in structural characteristics of the lignite during oxidation
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褐煤生成苯甲酸及其氧化过程中结构特征的变化
DOI：
10.1016/j.fuel.2017.04.096
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发表时间：
2017-09
期刊：
影响因子：
7.4
通讯作者：
Liu Zhenyu
中科院分区：
文献类型：
--
作者：
Yang Fan;Hou Yucui;Wu Weize;Liu Zhenyu
褐煤氧化生产羧酸(包括12种苯羧酸和小分子脂肪酸)已被广泛研究，但很少有人研究BCA的分布与褐煤结构的关系。用~(13)C核磁共振研究了小龙潭褐煤的碱氧氧化和BCA的分布，以及BCA的分布与褐煤结构的关系。结果表明，褐煤中主要的芳香族结构为萘和苯，摩尔比约为3，芳环的烷基取代度为0.359。这些结构特征决定了苯三元酸、苯四元酸、苯五元酸和苯丙酸的产率高于其他BCA。在氧化过程中，褐煤中的有机质首先转化为腐植酸，然后转化为水溶性酸，最后转化为羧酸。最后一个转换步骤是速率控制步骤。对残留物和HAS的分析表明，褐煤的C-O键很容易断裂。褐煤的芳香族结构(稠环除外)容易解聚，但稠环和长链烷基链不易被氧化。随着氧化时间的延长，残留物中芳香族结构的含量减少，而稠环和长链烷基链的含量均增加。而在HAS中，稠合芳环含量增加，但平均亚甲基链长(CN)减少。
Production of carboxylic acids (including 12 types of benzene carboxylic acids (BCAs) and small-molecule fatty acids) from lignite via oxidation has been widely studied, but few studies addressed the relationship between distribution of BCAs and structure of lignite. This work studies alkali-oxygen oxidation of Xiaolongtan lignite and distributions of BCAs with13C NMR as well as the relationship between the distributions of BCAs and the lignite structures. The results indicate that the dominant aromatic structures in the lignite are naphthalene and benzene with a mole ratio of around 3, and an alkyl-substituted degree of aromatic rings of 0.359. These structure characters determine that the yields of benzene tricarboxylic acids, benzene tetracarboxylic acids, benzene pentacarboxylic acid and mellitic acid are more than those of other BCAs. In the oxidation process, the organic matter of lignite is first converted to humic acids (HAs), then to water soluble acids, and last to carboxylic acids. The last conversion step is the rate-controlling step. Analyses of the residues and HAs indicate that C–O bond of lignite is easily cleaved. The aromatic structures (except condensed aromatic rings) are easily depolymerized from lignite, but the condensed aromatic rings and long alkyl chains are difficult to be oxidized. With an increase in oxidation time, in the residues, the contents of aromatic structures decrease, but the contents of condensed aromatic rings and long alkyl chains both increase. While in HAs, the contents of condensed aromatic rings increase, but the average methylene chain length (Cn) decreases.
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影响因子：
5.3
作者：
SOLUM, MS;PUGMIRE, RJ;GRANT, DM
通讯作者：
GRANT, DM
影响因子：
5.3
作者：
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影响因子：
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作者：
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影响因子：
7.4
作者：
Yang Fan;Hou Yucui;Wu Weize;Niu Muge;Ren Shuhang;Wang Qian
通讯作者：
Wang Qian
影响因子：
7.4
作者：
Li, Zhan-Ku;Wei, Xian-Yong;Zong, Zhi-Min
通讯作者：
Zong, Zhi-Min