基于分子轨道理论的缓蚀剂分子结构设计及其复配协同效应研究

The mixture of inhibitors shows good inhibition properties toward the corrosion of pipeline steels in oil and gas industry, which mainly depends on the electron transfer and bonding process between inhibitors and metal surface. The frontier orbital energetic position and the Fermi level of metal surface have great effect on the electron transfer and bonding process. Therefore, understanding the law of the frontier orbital energetic position of inhibitor component and the Fermi level of metal surface, will give a guiding significance to the design of molecular component, as well as the obtaining of an inhibitor mixture with high inhibition efficiency and universal applicable. However, the details mentioned above remains a great challenge in the design of new formulations of inhibitors. In order to obtain an inhibitor system with higher inhibition performance, the frontier orbital energetic position distributions of inhibitors and the Fermi level of metal surfaces will be computed. The elemental composition, functional group and the alkyl chain structure of inhibitor molecules will be optimized. The synergistic effect between inhibitors and additives will be studied and the relative mechanism will be proposed. Finally, the newly designed inhibitor molecule and the mixture of inhibitors with higher inhibition properties, in particular, a mixture of inhibitor mixture with universal applicable will be obtained.

油气集输过程中，金属管线的腐蚀问题突出。复配缓蚀剂可对金属起到很好的缓蚀效果，其对金属的保护程度取决于复配体系中分子在金属表面吸附时的电子转移成键性能的优劣。申请者通过前期研究和总结发现，复配缓蚀剂分子与金属基体的电子转移成键过程受各组分前线轨道能级分布与金属基体费米能级位置分布的影响。总结当前国内外研究结果发现，明确复配缓蚀剂分子前线轨道与金属费米能级分布规律，指导分子结构设计与合理优化前线轨道能级分布,成为缓蚀剂分子设计与获得高性能复配缓蚀剂体系环节中的一项重要挑战。因此，本项目以模拟计算获得缓蚀剂分子前线轨道能级分布为切入点，通过优化分子中元素、官能团与烷基链的组成与结构，获得高性能的缓蚀剂组份，实现与复配添加剂前线轨道及金属基体费米能级调控，最终明确复配缓蚀剂协同作用机制，指导提高复配缓蚀剂的缓蚀性能、改善其普遍适用性。

通过合成以及购买缓蚀剂等方式，准备了多种缓蚀剂样品，主要包含阳离子型、阴离子型和非离子型缓蚀剂三种类型。加工制备了失重测试用金属挂片材料，电化学测试用金属电极材料，采用环氧封装方法制备了电化学测试用工作电极。开展了酸化环境下碳钢在单一缓蚀剂组分及其与复配剂共同添加环境中的腐蚀行为，同时开展了相同腐蚀环境条件下的开路电位、电化学极化曲线以及电化学交流阻抗测试，分析了相关参数，包含阳极极化曲线斜率、阴极极化曲线斜率、自腐蚀电流密度、腐蚀电位、电荷转移电阻、膜电阻、电化学反应界面双电层电容等。构建了金属/缓蚀剂/溶液界面模型结构，探讨了缓蚀剂分子与金属表面的电荷转移、吸附成键相互作用规律，探讨了界面缓蚀剂吸附对水层的影响规律，结合失重测试与电化学分析测试方法结果进行了综合分析和对比探讨，主要获得了以下相关研究结果：首先，明确了酸性腐蚀环境中不同类型缓蚀剂对碳钢材料的缓蚀行为及其缓蚀作用规律，明确了复配缓蚀剂协同缓蚀作用规律；采用XPS表面分析辅助手段，明确缓蚀剂在金属表面吸附成键原子和官能团结构。采用分子动力学和第一性原理外层电子轨道分布规律研究，对比实验研究结果分析，明确了缓蚀剂吸附作用的得电子与失电子官能团结构。通过合理设计，设计了新型具有优异吸附性能的缓蚀剂分子。