Thermal decomposition of long-chain fatty acids and its derivative in the presence of montmorillonite
Thermal decomposition of long-chain fatty acids and its derivative in the presence of montmorillonite
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DOI：
10.1007/s10973-016-6022-5
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发表时间：
2017-06
影响因子：
4.4
通讯作者：
Hongling Bu;P. Yuan;Hongmei Liu;Dong Liu;Xiang Zhou
中科院分区：
文献类型：
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作者：
Hongling Bu;P. Yuan;Hongmei Liu;Dong Liu;Xiang Zhou
在沉积环境或富含粘土的岩石中，粘土矿物通常与有机质结合；然而，很少有研究关注有机质和粘土矿物的组合对有机物热降解和随后碳氢化合物生成的影响。本研究选择长链脂肪酸十八烷酸（OA）及其衍生物十八烷基三甲基溴化铵（OTAB）作为模型有机物。这些有机物是为与钠基蒙脱石 (Mt(Na)) 进行粘土有机缔合而制备的。通过热重（TG/DTG）分析研究了这些缔合体的热分解行为。在 Mt(Na) 存在下，OA 在 275.2 °C 时分解，比纯 OA 分解得更快。 OTAB 的热分解行为与纯 OTAB 几乎一致，但对于层间 OTAB，分解温度升高至 300 °C 以上。结果表明，Mt(Na)在脂肪酸的热分解中起着双重作用。 Mt(Na)可能会加速OA的热分解，而固有的固体酸度水平可能是关键因素。此外，Mt(Na)的层间结构可以提高OA和OTAB的热稳定性。上述结果进一步证明给定有机材料的热分解行为也可能取决于其结构和组成。在Mt(Na)存在下，具有氨基和胺结构的有机物比具有羧基的有机物更稳定。
In sedimentary environments or clay-rich rocks, clay minerals are usually combined with organic matter; however, little research has focused on the effects of combinations of organic matter and clay minerals on the thermal degradation of organics and on subsequent hydrocarbon generation. In this study, the long-chain fatty acid octadecanoic acid (OA) and its derivative octadecy trimethyl ammonium bromide (OTAB) were selected as model organics. The organics were prepared for clay–organic associations with Na-based montmorillonite (Mt(Na)). The thermal decomposition behaviors of these associations were studied via thermogravimetric (TG/DTG) analysis. In the presence of Mt(Na), OA decomposed at 275.2 °C, decomposing sooner than pure OA. The thermal decomposition behavior of OTAB is nearly consistent with that of pure OTAB, but for interlayer OTAB, the decomposition temperature increased to higher than 300 °C. The results indicate that Mt(Na) plays a dual role in the thermal decomposition of fatty acid. Mt(Na) may accelerate the thermal decomposition of OA, and inherent solid acidity levels may be the key factor. In addition, the interlayer structure of Mt(Na) can increase the thermal stability of OA and OTAB. The above results further demonstrate that the thermal decomposition behavior of a given organic material may also depend on its structure and composition. In the presence of Mt(Na), organics with amino and amine structures are more stable than those with carboxyl groups.