【作者】 胡松青；

【导师】 郭文跃；

【作者基本信息】 中国石油大学 ， 材料学， 2010， 博士

【摘要】 H₂S、CO₂腐蚀是世界石油工业中常见的腐蚀类型,对我国石油工业的发展也产生了非常大的影响。在H₂S、CO₂腐蚀防护中,使用缓蚀剂是国内外腐蚀防护的一种重要手段。目前所报道的缓蚀剂中抗高浓度H₂S和高浓度CO₂腐蚀的不多,并且价格较高,针对性很强,有待进一步研究开发。本文选取油田常用的15种十一烷基咪唑啉类缓蚀剂为研究对象,将应用在药物分子设计方面的定量构效关系方法移用到缓蚀剂分子设计上,通过分子动力学模拟和量子化学方法对设计出的新分子可能具有的缓蚀性能进行了理论预测,并采用实验方法对设计结果进行验证。通过系统的分析研究得到如下结果:采用量子化学密度泛函理论（DFT）和多元回归分析方法对15种十一烷基咪唑啉衍生物缓蚀剂的反应活性及微观结构与其抗H₂S、CO₂缓蚀效率之间的关系进行了研究,建立了缓蚀剂缓蚀性能预测的QSAR模型,结果表明,分子的反应活性区域和活性位点主要集中在咪唑啉分子的头部,咪唑环和亲水取代基上的杂原子是分子的主要活性位点,而烷基尾链对活性几乎不产生影响;电子转移参数ΔN、咪唑环上非氢原子净电荷之和ΣQring及分子极化率α对咪唑啉类缓蚀剂的缓蚀性能有很大的贡献,增加分子的ΔN和α值、降低ΣQring能显著改善缓蚀剂的缓蚀效率。在QSAR研究的基础上,结合软硬酸碱（SHAB）理论和分子内协同效应,通过改变取代基R2上的基团或原子来改变缓蚀剂分子结构参数值如ΔN,ΣQring、α,设计了4个烷基链长为11的新缓蚀剂分子。QSAR模型预测结果表明所设计的4个缓蚀剂分子都具有较好的抗H₂S、CO₂腐蚀性能。根据前人的研究结果,对所设计的四种新型咪唑啉缓蚀剂分子的烷基链长度进行了修正,并采用分子动力学模拟（MD）和量子化学计算（QC）相结合的方法对所设计的新缓蚀剂分子进行理论筛选和评价。MD结果表明,当亲水官能团相同时,烷基链长为15的分子较烷基链长为11、17的分子具有更大的吸附能。烷基链长为15的四种新缓蚀剂分子A、B、C、D与金属界面发生吸附时,分子上的咪唑环和亲水支链优先吸附,烷基长链以一定的倾角远离金属表面,形成一层疏水膜,阻碍腐蚀介质向金属表面迁移;分子在Fe表面的吸附稳定性按D、C、A、B的顺序逐渐减弱。QC结果显示,A、B、C、D分子的反应活性主要分布在咪唑环和亲水支链上,具有多个反应活性位点,能在金属表面形成多中心吸附。D分子具有最强的反应活性,C、A、B分子的反应活性依次减弱。采用溶剂法对所设计的前三种分子进行了合成,并采用失重法和电化学极化曲线及交流阻抗等方法对其在H₂S/CO₂共存的盐溶液中对Q235钢的缓蚀性能进行了评价,结果表明三种缓蚀剂都具有较好的缓蚀性能,其平均最佳缓蚀效率分别为92.96%、90.72%、94.36%,最佳缓蚀剂添加浓度为100mg/L,验证了计算机模拟方法进行分子设计的正确性。最后,采用失重法研究了1-（2-甲基-硫脲乙基）-2-十五烷基-咪唑啉（B）与2-氨基噻唑（AT）复配对Q235钢在CO₂/H₂S共存盐溶液中缓蚀协同作用,结果表明,相同条件下复配缓蚀剂的缓蚀性能较复配前有了较大的提高,在含有50mg/L缓蚀剂B的腐蚀溶液中加入AT的浓度达到200mg/L时其缓蚀效率为97.63%,并通过两者复配的协同参数证明了协同效应的存在。B+AT的加入能够显著增加腐蚀反应的表观活化能,其在Q235钢表面的吸附符合Langmiur吸附等温式,吸附过程为自发的放热过程,也是熵减小的过程,吸附方式为以化学吸附为主的混合吸附。更多还原

【Abstract】 H₂S and CO₂ corrosion, is a common corrosion type in the world oil industry, also is one of the prominent problems which plagued the development of petroleum industry of China. In the H₂S and CO₂ corrosion protection, the use of inhibitor is a significant measure at home and abroad. At present, the inhibitor which resists high concentration of H₂S and CO₂ is reported rarely, and highly priced, and also has high pertinence, depending on the further development. In this paper, 15 kinds of undecyl imidazoline corrosion inhibitors commonly used in oil field were chosen to be research objects.The quantitative structure-activity relationship （QSAR） of undecyl imidazoline corrosion inhibitors for anti-corrosion behavior towards hydrogen sulfide and carbon dioxide was studied using density functional theory （DFT） and regression analysis methods. A stepwise regression analysis was used to determine the main independent factors that affect the activity of the compounds and a QSAR model was established. We found that the electron transfer parameter （ΔN）, the electrostatic charge of non-hydrogen atoms in the imidazole ring （ΣQring） and the mean molecular polarizability （α） were the main independent factors that contribute to corrosion inhibition. Based on the QSAR model, combination of hard and soft acid-base theory and intramolecular synergistic effect, via modifying substituent R2 structures to improve the values of the three parameters, such asΔN,ΣQring, andα, we have theoretically designed 4 new compounds. The predicted results by QSAR model show that the four inhibitors all have excellent anti-corrosion of hydrogen sulfide and carbon dioxide The method of quantitative structure-activity relationship which used for design drug molecules was applied to the inhibitor molecular designing, through theoretical and experimental methods to verify the design results . The systemic research results are as follows: activities.According to the results of previous studies, alkyl chain lengths of four new imidazoline corrosion inhibitor molecules were revised, and its inhibition performance was theorectically filtered and evaluated using molecular dynamic simulations （MD） and quantum chemistry calculations （QC）. MD result shows that the corrosion inhibitor molecule with alkyl chain length of 15 has better adsorption energy than the molecules whose alkyl chain length is 11 or 17 when hydrophilic groups are the same. When the adsorption process occurs, the ring of imidazole and the hydrophilic chain were firstly adsorbed to the metal surface, and the non-polar alkyl chain deviated from the surface and self-assemblies into a compactly-arranged hydrophobic membrance. The adsorption stability weakens gradually in the order of D, C, A and B. Quantum chemistry calculation results indicated that the reaction activity sites mainly concentrated in the imidazole ring and heteroatoms. D bore the highest reaction activity among the four molecules. The reaction activity weakens gradually in the order of D, C, A and B.The first three molecules we designed were synthesized by solvent method and the corrosion inhibition performance for mild steel corrosion under the condition of H₂S and CO₂ coexistence were investigated by weight loss method, polarization curve and electrochemical impedance spectroscopy （EIS）. The results indicated that the three inhibitors all have excellent corrosion inhibition performance. The average highest inhibition efficiencies of the three corrosion inhibitors are 92.96%, 90.72% and 94.36%, respectively. The best added concentration is 100mg/L, which verified the correctness of molecular design by computer simulation method.The synergetic adsorption and corrosion inhibition properties of 1-（2-methyl- thioureaethyl）-2-pentadecyl-imidazoline （B） and 2-aminothiazole （AT） for Q235 steel corrosion under H₂S and CO₂ coexistence were investigated by weight loss method. Results showed that the combined inhibitor strongly inhibited the corrosion of Q235 steel. The corrosion inhibition efficiency using 50mg/L B was 97.63%. The inhibition efficiency increases with increasing in inhibitor concentration but decrease with the temperature, and it has good and high temperature performance. Adsorption obeyed Langmuir isotherm. It was spontaneous and exothermic, and belonged to mix-type adsorption which mainly dominated by chemisorptions.更多还原