咪唑啉缓蚀剂缓蚀性能的理论研究

THEORETICAL STUDY ON CORROSION INHIBITION PERFORMANCE OF IMIDAZOLINE INHIBITORS

采用量子化学计算、分子动力学模拟和分子力场相结合的方法,评价了5种具有不同烷基链长的2-烷基-1-氨乙基咪唑啉缓蚀剂抑制CO2腐蚀的性能,并分析了其缓蚀机理。结果表明,5种缓蚀剂分子的反应活性区域均集中在咪唑环上,亲电反应中心为3个N原子,可在金属表面形成多中心吸附;当烷基碳链长度大于11时,缓蚀剂在金属表面可形成一层高覆盖度、致密的疏水膜,可有效阻碍溶液中的腐蚀介质向金属表面扩散,从而达到阻碍或延缓腐蚀的目的;缓蚀剂膜的稳定性以及膜与金属基体的结合强度随链长的增加而增大。缓蚀剂缓蚀性能的理论评价结果与实验结果基本吻合。

The inhibition performance of five 2-alkyl-l-aminoethyl imidazolines with different alkyl lengths in CO2 corrosion was evaluated by combination of quantum chemistry, molecular dynamics simulation and molecular mechanics, and the corrosion inhibiting mechanism was also analyzed. The results indicated that the active reaction zones of the five 2-alkyl-1-aminoethyl imidazolines were located in the imidazole ring of their molecules. The electrophilic attack centers of the inhibitors were on the three nitrogen atoms, which favored multi-center adsorption on metal surfaces. Only when the number of carbon atoms in the alkyl chain of the inhibitor was more than 11, a dense and high coverage hydrophobic membrane could be formed with the inhibitor molecules on metal surface, preventing efficiently the corrosive media in solutions from diffusing to the surface so as to slow down or even check the corrosion processes. The stability and binding ability of inhibiting membrane were enhanced with the increase of the alkyl length in the molecule of 2-alkyl- 1-aminoethyl imidazoline. The theoretical evaluation accorded well with the experiment results.