1-(2-羟乙基)-2-烷基-咪唑啉缓蚀剂缓蚀机理的理论研究

采用量子化学计算、分子动力学模拟和分子力学相结合的方法, 对6种不同烷基链长的1-(2-羟乙基)-2-烷基-咪唑啉缓蚀剂抑制H2S腐蚀的缓蚀机理进行研究, 并对其缓蚀性能进行评价. 前线轨道分布和Fukui指数表明, 6种缓蚀剂分子的反应活性区域均集中在分子的咪唑环上, 3个反应活性中心分别位于咪唑环上的N(4), N(7)和C(8)原子, 可使咪唑环在金属表面形成多中心吸附. 分子的反应活性及活性区域分布对烷基链长并不敏感. 单分子吸附能、膜的内聚能、吸附角和链间距的计算数据显示, 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; 当正构烷基碳链长度大于13时, 缓蚀剂可在金属表面形成一层高覆盖度、致密的疏水膜, 能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.

Theoretical Investigation on Inhibition Mechanism of 1-(2-Hydroxyethyl)- 2-alkyl-imidazoline Corrosion Inhibitors

The inhibition mechanism of six corrosion inhibitors against H2S corrosions has been theoretically studied using quantum chemistry calculations,molecular dynamics simulations and molecular mechanics,and the inhibition performance was also evaluated. Front orbital distributions and Fukui indexes indicate that active reaction zones of the molecules are located in the imidazoline ring,which possesses three reactive sites of N(4),N(7) and C(8),enabling the ring to be multicenteredly adsorbed on metal surface. The calculated mono-molecular adsorption energies,membrane cohesive energies,distance of alkyl chains,and adsorption angles suggest that the stability and binding ability of the inhibiting membrane be enhanced with the increase of the alkyl length. When the number of carbon atoms in the alkyl chain is more than 13,the inhibitors can form a dense and high coverage hydrophobic membrane on metal surface,which can prevent efficiently the corrosive media in solutions from diffusing to the surface so as to slow down or even check the corrosion processes.