咪唑啉衍生物的缓蚀机理计算及性能研究

采用量子化学方法分析了咪唑啉衍生物的结构特征，设计了3种咪唑啉衍生物：咪唑啉、甲苯基咪唑啉、硝基苯基咪唑啉；对其分子结构、电荷分布、轨道能量，及其与Fe原子配位的结合能和配位化合物的结构特征进行了计算，分析Fe原子与不同咪唑啉衍生物分子间作用力和结合能的变化规律；进而，合成得到3种相应的化合物，对其缓蚀性能进行评价。结果表明：咪唑啉类缓蚀剂的缓蚀性能由强到弱的顺序为：甲苯基咪唑啉>咪唑啉>硝基苯基咪唑啉。咪唑啉衍生物分子中取代基供电子能力越强，咪唑啉衍生物分子和Fe原子的前线分子轨道能量差越小，二者发生配位作用吸附在金属表面的作用效果越好，缓蚀剂的缓蚀性能越优秀。     

富含双键咪唑啉在饱和CO2盐水中缓蚀行为研究

目的 合成含有两个双键的亚油酸咪唑啉,与传统的含有单个双键油酸咪唑啉对比,研究其结构对其缓蚀性能的影响。方法 在60℃下将Q235钢浸泡于饱和CO₂的3%(w)NaCl溶液中,通过失重、电化学测试和缓蚀效率测试,并通过表面分析方法观察腐蚀后钢片形貌变化,最后通过理论计算对合成缓蚀剂进行性能研究。结果 电化学与失重结果显示在加入质量浓度为200 mg/L的亚油酸咪唑啉后,缓蚀效率能达到90%,缓蚀性能优于常见的油酸咪唑啉。在结构上,由于亚油酸咪唑啉分子比油酸咪唑啉多了一个双键,增加了咪唑啉缓蚀剂的吸附位点,使其能更好地吸附于金属的表面。结论 亚油酸咪唑啉对碳钢有很好的缓蚀性能;在同等实验条件下,缓蚀性能优于油酸咪唑啉;其吸附满足Langmuir吸附等温线;吸附过程中主要通过N—Fe键吸附在Fe表面。     

咪唑啉衍生物缓蚀性能的密度泛函理论和分子动力学模拟

 采用挂片失重法测得A、B、C、D 4种咪唑啉衍生物缓蚀剂在CO2饱和的3%NaCl溶液中的缓蚀效率,并利用量子化学计算和分子动力学模拟相结合的方法对它们的缓蚀性能进行了理论分析。结果表明,咪唑啉类缓蚀剂对金属的缓蚀作用,主要是其分子中的咪唑环和极性基团起作用;发生吸附时,咪唑啉衍生物分子上的咪唑环优先吸附在金属表面,然后牵引烷基支链R平行吸附在金属上。综合量子化学和分子动力学模拟计算得出4种新型缓蚀剂的缓蚀效率从大到小依次为B、C、A、D,与实验结果相吻合。     

酰胺咪唑啉季铵盐合成及其缓蚀性能

以高纯环烷酸为原料合成了系列酰胺咪唑啉季铵盐水溶性缓蚀剂,探讨了其咪唑啉环N₍₁₎原子上取代基与缓蚀性能之间的关系。采用取代基电子效应法和碳钢挂片失重法,从理论与实验两方面探讨了酰胺咪唑啉季铵盐对碳钢的缓蚀性能。利用数理统计方法得出,其缓蚀效率(η)与基团极化效应参数(PEI_x)和-C=C-键效应指示变量D之间符合定量线性关系η = a + b PEI_x + c D(a,b,c为常数),相关系数R≥0.996。该研究成果,能为离子型缓蚀剂分子设计提供一种简便易行的新方法,为找到具有更佳缓蚀性能的新型咪唑啉缓蚀剂提供参考。     

三种双子季铵盐缓蚀剂对钢片在气田采出水中缓蚀行为的影响

为获得缓蚀性能优良的双子咪唑啉季铵盐缓蚀剂,以3种不同的胺类化合物与环氧氯丙烷和硫脲为原料,合成了3种双子咪唑啉季铵盐缓蚀剂(甲硝唑双子季铵盐G1、不对称咪唑啉季铵盐G2和双咪唑啉季铵盐G3),采用化学浸泡失重法、电化学极化曲线及电化学阻抗谱(EIS)技术研究了3种缓蚀剂对X52钢在某气井采出水(矿化度34330 mg/L)介质中的缓蚀行为,考察了缓蚀剂浓度对缓蚀效率的影响,分析了双子季铵盐缓蚀剂作用机理。结果表明,缓蚀剂G1和G2为非对称结构,缓蚀剂G3为对称结构。3种缓蚀剂均表现出优异的缓蚀性能。在76℃下,随着3种缓蚀剂浓度的增加,X52钢的腐蚀速率显著降低,缓蚀效率增加。3种缓蚀剂缓蚀能力从强到弱的顺序为G3G2G1。3种缓蚀剂在X52钢表面的吸附缓蚀作用均满足Langmuir等温吸附曲线,吸附作用为物理吸附和化学吸附协同作用的混合型吸附模式。3种双子季铵盐缓蚀剂均为阳极抑制为主的混合型缓蚀剂,其在X52钢表面的成膜作用对双电层的影响较大。由于3种缓蚀剂分子结构及对称性的差异,影响了吸附过程中X52钢表面的覆盖度,导致了三者成膜行为和缓蚀性能的不同。图12表2参23     

酸化用双环咪唑啉季铵盐缓蚀剂的合成与性能评价试验

以己二酸、二乙烯三胺为原料合成了双环咪唑啉缓蚀剂JUC,并对其季铵化后得到了适于酸化用的双环咪唑啉季铵盐缓蚀剂JUCI;采用静态挂片失重法对合成的缓蚀剂在酸化条件下的缓蚀性能及与非离子表面活性剂SA-1复配后的缓蚀性能进行了评价研究.结果表明,合成的JUC和JUCI缓蚀剂对N80钢(油管用)在盐酸和土酸体系溶液中有较好的缓蚀作用;JUC和JUCI缓蚀剂中加入少量SA-1后,可增加缓蚀效果;双环咪唑啉季铵盐JUCI缓蚀剂比双环咪唑啉JUC缓蚀剂的缓蚀效果好.     

2-氨乙基十七烯基咪唑啉缓蚀性能评价

实验以二乙烯三胺和油酸为原料,经升温脱水合成咪唑啉缓蚀剂。以正交试验法和静态失重法研究了以油酸和二乙烯三胺为反应物、二甲苯为携水剂合成咪唑啉缓蚀剂时在模拟采出水中其反应物配比、合成温度、合成反应时间对咪唑啉缓蚀剂缓蚀性能的影响。经红外光谱、咪唑啉缓蚀性能实验表明,其最佳合成反应条件为:n(油酸):n(二乙烯三胺)=1.0:1.0、合成温度为170℃,反应时间为8 h,此时缓蚀效率最佳达95%;实验室评价结果表明:该种缓蚀剂的最佳使用温度为50℃,当质量浓度为250 mg/L时缓蚀率可达96%;腐蚀试片腐蚀形貌分析可知,该种缓蚀剂能抑制点蚀;通过添加不同浓度缓蚀剂电化学曲线实验表明,该种缓蚀剂为混合型缓蚀剂。     

咪唑啉类缓蚀剂腐蚀抑制作用

CO2-H2S腐蚀一直是石油工业的一个棘手问题和研究热点。CO2-H2S腐蚀引起的设备和管道腐蚀失效,造成了巨大的经济损失以及严重的社会后果,所以开展抑制CO2-H2S腐蚀的研究具有深远的经济和社会效应。而咪唑啉类缓蚀剂具有优良的缓蚀性能,随着缓蚀剂质量浓度增加,缓蚀率增加,当N-烷基苯并咪唑啉阳离子缓蚀剂质量浓度为50 mg/L时,缓蚀率达到97.15%。近年,针对CO2-H2S腐蚀问题,采用咪唑啉缓蚀剂处理的研究较多,通过金属与酸性介质接触在其表面形成单分子吸附膜,从而降低其电位达到缓蚀的目的。文中对新型咪唑啉类缓蚀剂(季铵盐、酰胺基、硫脲基、苯并和膦酰胺味唑啉类缓蚀剂)的缓蚀机理以及研究现状作了详尽的概述。     

双咪唑啉季铵盐的合成及缓蚀抑菌性能研究

合成了氯化1, 2-二(N-苯基-N-氨乙基咪唑啉)乙烷(PIM-2-IMP)双咪唑啉季铵盐缓蚀剂。采用静态失重法和电化学方法评价了PIM-2-IMP对N 80钢在5%HCl溶液中的缓蚀性能,采用绝迹稀释法考察了PIM-2-IMP对胜利油田坨六污水中硫酸盐还原菌(SRB)的抑菌性能。结果表明:PIM-2-IMP缓蚀剂是一种混合抑制性缓蚀剂,缓蚀效率随缓蚀剂浓度的增大而增大。在30℃下,缓蚀剂浓度为1 mmol/L时,缓蚀效率可达到92.67%。当污水中硫酸盐还原菌的浓度在1×(10⁴～10⁵)个/mL时,杀菌剂的浓度小于40 mg/L,小于油田标准要求的70 mg/L。     

改性咪唑啉季铵盐缓蚀剂的合成及性能评价

以油酸,多胺,氯化苄和苯甲酸为原料,在咪唑啉分子结构中引入苯环及O,N杂原子,增加与Fe原子配位吸附的新位点,最终复配得到一种新型咪唑啉季铵盐缓蚀剂。采用红外光谱对合成产物进行表征,结果表明苯甲酰基成功引入咪唑啉分子中。通过静态挂片失重法评价了缓蚀剂的缓蚀性能,结果表明,缓蚀剂MZL-A明显降低了N80钢在模拟矿化水中的腐蚀速率,当缓蚀剂加量为80mg/L时,缓蚀率可达到85%以上。采用电化学方法对缓蚀剂的机理进行研究,结果表明缓蚀剂对电极的阴阳两极均起到了抑制作用,且自腐蚀电位负移,合成的缓蚀剂是以抑制阴极为主的混合型缓蚀剂。     

Chemical and electrochemical studies of the inhibition performance of hydro-alcoholic extract of used coffee grounds (HECG) for the corrosion of C38 steel in 1M hydrochloric acid

The corrosion protection of C38 steel in 1M HCl solution with hydro-alcoholic used coffee grounds extract (HECG) was studied using measurements of hydrogen gas evolution, potentiodynamic polarization and electrochemical impedance spectroscopy. This work revealed that the HECG studied acts as a mixed type inhibitor. It has also been shown that the corrosion inhibition efficiency (IE) increases with increasing extract concentration, an IE value of 97.4% was reached with 2 g/L HECG. The inhibitory action of the inhibitor was mainly due to the adsorption of HECG molecules on the C38 steel surface. The studies have shown that HECG adsorbs on the C38 steel surface according to Langmuir's isotherm, with a standard free energy (ΔG⁰_ads) of −18,477 KJ mol⁻¹, which means that HECG delays the corrosion process by physical adsorption. The scanning electron microscope (SEM) study confirmed that corrosion inhibition of C38 steel occurs by adsorption of inhibiting molecules on the metal surface. These results show that the HECG can be used as an excellent corrosion inhibitor for C38 steel in a hydrochloric acid medium.     

Experimental and theoretical investigation of a new triazole derivative for the corrosion inhibition of carbon steel in acid medium

A new triazole derivative, (E)-4-(4-(dimethylamino)benzylideneamino)-5-(pyridin-4-yl)-2H-1,2,4-triazole-3(4H)-thione (DPT), was synthesized and characterized using spectral data. The electrochemical experimental techniques were utilized to evaluate the inhibition efficiency (IE) of DPT for the corrosion of C1018 carbon steel. The studies revealed that, DPT is highly efficient with IE value 90% at 250 ppm. Further, the addition of DPT resulted in the decrease of cathodic as well as anodic current densities which is the indication of mixed-type inhibition. Also, the studies inferred the Langmuir model for DPT-metal adsorption. The surface morphological studies of C1018 carbon steel with and without DPT was investigated using SEM, EDX, and XPS, which indicated the strong adsorption of metal-DPT. Monte-Carlo simulation and Density functional theory approaches had been employed for correlating the structure of DPT and its corrosion inhibition ability. The high IE values of DPT observed in experimental studies were in agreement with the theoretical studies, and hence DPT acts as good inhibitor for the corrosion of C1018 steel.     

Corrosion inhibition efficiency of water soluble ethoxylated trimethylol propane by gravimetric analysis

Polyoxyethylenated trimethylol propane monolaurate surfactants with varied ethylene oxide content were tested as corrosion inhibitors via the weight loss method. Weight loss measurements for carbon steel dissolution were performed in 1 N HCl containing different inhibitor concentrations at 30, 40 and 50 °C. These measurements were utilized for calculating corrosion rate, surface coverage area and percentage inhibition. The obtained data show that the adsorption of these inhibitors obeys Langmuir adsorption isotherm. Thermodynamic parameters (ΔG¹, ΔH¹ and ΔS¹) of the corrosion process are evaluated and correlated to inhibitors structures.     

Modelling of methane hydrate formation pressure in the presence of different inhibitors

Formation of gas hydrates is one of the problems in the production, processing, and transportation of natural gas. Hence, an understanding of conditions where hydrates form is necessary to overcome hydrate-related issues. The aim of this study was to develop an effective relation between the methane hydrate formation pressure based on the temperature, weight fraction of inhibitor, and molecular weight of inhibitor using the least square support vector machine. This computational model indicates the great ability of predictions for determining hydrate pressure in the presence of different inhibitors such as the methanol, ethylene glycol, diethylene glycol, and triethylene glycol. The values of R-squared (R²) and mean squared error obtained for this model are 0.9925 and 0.2325, respectively. This developed predictive tool can be applied as an accurate estimation of methane hydrate formation pressure.     

Dispersion of Asphaltene Precipitation in Egyptian Crude Oil Using Corrosion Inhibitors

Three corrosion inhibitors are examined in this work to control asphaltene precipitation in Egyptian heavy crude oil. Dodecylbenzenesulfonic acid (DBSA), 4-nonylphenyl-polyethylene glycol, and synthetic cationic gemini surfactant: N₂,N₃-didodacyl-N₂,N₂,N₃,N₃-tetramethylbutane diaminium bromide displayed highest capacity to inhibit asphaltene deposition. The H¹-NMR spectroscopy was used to confirm the chemical structure of the synthetic inhibitor. The efficiency of the studied additives as corrosion inhibitors are evaluated by weight loss method using the same crude oil. The effect of the mentioned corrosion inhibitors as asphaltene inhibitors is studied. The studied inhibitors are with dual nature for inhibition of both corrosion and asphaltene precipitation.     

MRL and PLS Correlations between the 1H NMR Spectra of Vacuum Residues and the Deasphalting Conditions with the DMO Yields

Abstract

The areas of signals present in 12 consecutive frequency bins of the ¹H nuclear magnetic resonance (NMR) spectra of different vacuum residues (VRs) were correlated with the yield of the deasphalting/demetallization process (DEMEX) under fixed and variable conditions (antisolvent/load ratio and rectification temperature). Prediction models for the demetallized oil (DMO) obtained under variable process conditions generated by partial least squares (PLS) regression had R² = 0.950 and the CV-q² was 0.943. Models obtained with multiple linear regression (MLR) for the same process had R² = 0.93 but with a significantly lower CV-q² (0.608) value. The prediction models for the DMO yield under a set of fixed conditions was such that R² = 0.930 for the PLS whereas for the MRL method it was 0.970. Again, the CV-q² value was higher for the PLS (0.998) than for the MRL method (0.610). The proposed correlation methods are much faster and significantly less costly than the conventional ones used for predicting the yield of the DMO process.     

Development of production technology of imidazoline corrosion inhibitors

Imidazoline corrosion inhibitors of have been prepared from vegetable oil industry waste and polyethylenepolyamide. The protective ability and corrosion rate of the imidazoline products have been determined via gravimetric and energy-dispersive X-ray fluorescence spectral analysis methods. The best protective effect is at corrosion rate of 0.2 g/(mm² h). The imidazoline products based on the vegetable waste feedstock meet the main characteristics of commercial analogue, thus holding promise for using them as a component of industrial corrosion inhibitors.