唑类缓蚀剂的性能评价及其在Cu表面吸附机理的实验与分子模拟研究

发布时间：2018-10-09 19:42

【摘要】：铜及铜合金具有广泛的应用,但在含有SO2、H2S和Cl2的气体介质中以及在氨、铵盐、氯化物等溶液中容易被强烈腐蚀。在众多防腐蚀措施中,添加缓蚀剂因其具有诸多优点而成为当前最为有效的防腐蚀方法之一。本文以咪唑(IMD)、三氮唑(TRI)、苯并咪唑(BIMD)和苯并三氮唑(BTA)缓蚀剂分子为研究对象,从实验和理论模拟两方面研究了缓蚀剂的缓蚀性能及其吸附机理。首先通过实验方法得到了四种缓蚀剂的缓蚀效率,然后进一步分析了其缓蚀剂类型并建立吸附等温模型;其次,通过分析四种缓蚀剂分子的全局活性参数,建立其缓蚀效率与全局活性参数之间的关系;再次,通过分析四种缓蚀剂分子的局部活性参数,明确其局部活性位点;最后,通过建立中性和质子化形式缓蚀剂分子在Cu表面的吸附模型,分析分子和金属表面的电子结构参数,得到缓蚀剂分子与Cu表面之间的微观吸附机理。研究结果如下:实验研究得到四种缓蚀剂缓蚀效率由高到低顺序为:苯并三氮唑苯并咪唑三氮唑咪唑,四种缓蚀剂均为混合抑制型缓蚀剂,在铜表面的吸附符合Langmuir吸附模型,且既有物理吸附,又有化学吸附;四种缓蚀剂的前线轨道均分布在分子的环状结构上,且分子中各原子亲电活性中心和亲核活性中心主要集中在分子中的杂原子N上。四种缓蚀剂分子的全局活性参数亲电指数ω与缓蚀剂缓蚀效率相关性均较好,说明缓蚀剂缓蚀效率值与上述全局反应活性参数值有关,可用上述参数值预测缓蚀剂缓蚀效率;四种缓蚀剂分子均可在金属表面发生化学吸附和物理吸附,且具有双环结构的苯并咪唑和苯并三氮唑吸附能要大于单环结构的咪唑和三氮唑,这与实验测得的缓蚀剂的缓蚀效率一致。缓蚀剂分子与铜表面之间的化学吸附通过缓蚀剂分子中的N原子与Cu原子之间形成化学键,且所形成的化学键为共价键,N原子与Cu原子之间的成键是N原子的s、p轨道杂化以及N原子的p轨道与Cu原子d轨道的相互作用所致;缓蚀剂在Cu表面的物理吸附包括范德瓦尔斯力相互作用和静电相互作用。
[Abstract]:Copper and copper alloys are widely used, but they are easy to be corroded strongly in gas medium containing SO2,H2S and Cl2 and in ammonia, ammonium salt, chloride and other solutions. Among the many anticorrosive measures, the addition of corrosion inhibitor has become one of the most effective corrosion prevention methods because of its many advantages. In this paper, imidazole (IMD), triazolium (TRI), benzimidazole (BIMD) and benztriazole (BTA) inhibitor molecules were used as the research objects. The inhibition performance and adsorption mechanism of the inhibitor were studied from the aspects of experimental and theoretical simulation. The corrosion inhibition efficiency of the four inhibitors was obtained by the experimental method, and then the types of the inhibitors were analyzed and the adsorption isothermal model was established. Secondly, the global activity parameters of the four inhibitors were analyzed. The relationship between the inhibition efficiency and the global active parameters is established. Thirdly, by analyzing the local activity parameters of the four inhibitor molecules, the local active sites are determined. By establishing the adsorption model of neutral and protonated inhibitor molecules on Cu surface, the electronic structure parameters of molecular and metal surfaces are analyzed, and the microscopic adsorption mechanism between inhibitor molecule and Cu surface is obtained. The results are as follows: the corrosion inhibition efficiency of the four inhibitors from high to low order is: benztriazole benzimidazole triazolidazole, four corrosion inhibitors are mixed inhibitor, the adsorption on the surface of copper accords with Langmuir adsorption model. The frontier orbitals of the four corrosion inhibitors are distributed in the ring structure of the molecule, and the electrophilic active centers and nucleophilic active centers of the molecules are mainly concentrated on the heteratomic N in the molecules. The electrophilic index 蠅 of the four kinds of corrosion inhibitor molecules has a good correlation with the corrosion inhibition efficiency of the corrosion inhibitor, which indicates that the corrosion inhibition efficiency of the corrosion inhibitor is related to the global reactive activity parameter, and the corrosion inhibition efficiency can be predicted by the above parameters. The chemisorption and physical adsorption of the four inhibitor molecules on the metal surface were observed, and the adsorption energy of benzimidazole and benztriazole with double ring structure was higher than that of imidazole and triazole with monocyclic structure. This is consistent with the corrosion inhibition efficiency measured experimentally. The chemisorption between the inhibitor molecule and the copper surface forms a chemical bond between the N atom and the Cu atom in the inhibitor molecule. The chemical bonds formed are due to the interaction between N atom and Cu atom and the interaction between Cu atom d orbital and P orbital of N atom. The results are as follows: (1) the covalent bond between N atom and Cu atom is due to the Schip orbital hybridization of N atom and the interaction of P orbital of N atom with d orbital of Cu atom. The physical adsorption of corrosion inhibitor on Cu surface includes van der Waals force interaction and electrostatic interaction.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG174.42

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