Alhreez Mahmoud, Wen Dongsheng
School of Chemical and Process Engineering, University of Leeds Leeds UK
School of Aeronautic Science and Engineering, Beihang University Beijing China
RSC Adv. 2019 Jun 24;9(34):19560-19570. doi: 10.1039/c9ra02664a. eCollection 2019 Jun 19.
Molecular structure characteristics and morphological features of asphaltene can be significantly influenced by the addition of asphaltene inhibitors (AI). We have recently developed a novel concept of using nanoemulsions (NE) as carriers for controlled release of asphaltene inhibitors, which could prohibit the precipitation problem with reduced AI quantity. In this work, X-ray diffraction (XRD) was utilized to investigate the changes in the stacking behaviour of asphaltenes in the presence of three cases: (i) strong organic acids (dodecyl benzene sulfonic acid, DBSA), (ii) nanoemulsions (blank NEs), and (iii) nanoemulsion loaded DBSA (DBSA NEs). Based on the XRD and transmission electron microscopy (TEM) analyses, the stacking distance between aromatic rings of asphaltene was found to be increased by 22.2%, suggesting that the modification of the π system over the aromatic zone prevented the ultimate π-π interactions between asphaltene sheets. The evidence of multiple intermolecular interactions quantitatively obtained from Fourier-transform infrared spectroscopy (FTIR) supported our proposed mechanism for controlled release effect and long-term asphaltene stability, , the decrease of the aromaticity and the reduction in the aliphatic side chains of asphaltene. The refractory nature of asphaltenes was examined by thermogravimetric analysis (TGA), which showed that the asphaltene structure was improved considerably and the coke yield was decreased by 62% due to the decrease of the cluster size and the increase of the stacking distance.
沥青质抑制剂（AI）的添加会显著影响沥青质的分子结构特征和形态特征。我们最近提出了一种新的概念，即使用纳米乳液（NE）作为沥青质抑制剂控释的载体，这样可以在减少AI用量的情况下防止沉淀问题。在这项工作中，利用X射线衍射（XRD）研究了在三种情况下沥青质堆积行为的变化：（i）强有机酸（十二烷基苯磺酸，DBSA），（ii）纳米乳液（空白NE），以及（iii）负载DBSA的纳米乳液（DBSA NE）。基于XRD和透射电子显微镜（TEM）分析，发现沥青质芳环之间的堆积距离增加了22.2%，这表明芳环区域上π体系的修饰阻止了沥青质片层之间最终的π-π相互作用。从傅里叶变换红外光谱（FTIR）定量获得的多种分子间相互作用的证据支持了我们提出的控释效应和沥青质长期稳定性的机制，即沥青质芳香性的降低和脂肪族侧链的减少。通过热重分析（TGA）研究了沥青质的难熔性质，结果表明，由于聚集体尺寸的减小和堆积距离的增加，沥青质结构得到了显著改善，焦炭产率降低了62%。
