Experimental and computational studies of novel cyclic ammonium based ionic liquids as corrosion inhibitors for carbon steel in acid medium.

The challenge of corrosion posed as a result of acidic sittings is considered as a major industrial concern, wherein ionic liquids serve as crucial in addressing the corrosive impacts on metals. In this study, five selected cyclic ammonium based ionic liquids were synthesized; IL-1MPyrBr, IL-1MPipBr, IL-2PyBr, IL-3MPyBr and IL-4MPyBr and their chemical structures were characterized using a variety of spectroscopic techniques (FT-IR, IH-NMR, 13C-NMR, Elemental analysis and thermal gravimetric analysis (TGA). Their corrosion inhibition efficiency was studied on carbon steel in 1 M HCl via different concentrations at 298 K using chemical and electrochemical parameters (PDP and EIS). DFT quantum parameters were computed, and the noted results were in complete compatible with the experimental. The synthesized ILs recorded excellent inhibition on the carbon steel corrosion in acidic media with increasing efficiency by increasing the inhibitor concentrations from 20 to 100 ppm. Different cations in the synthesized ILs affect the anti-corrosion effect and IL-3MPyBr showed the highest inhibition (ηR); 96.12% using the lowest concentration. Kinetic and thermodynamic considerations were studied and illustrated.

Surface active dicationic ionic liquids as green oil spill dispersants.

The utilization of chemical dispersants as a way of mitigating of oil spills in marine eco-system has been extensively documented worldwide. Hence, in this research we have successfully synthesized two amphiphilic asymmetric Dicaionic Ionic Liquids (DILs). The efficacy of these synthesized DILs as dispersants was assessed using the baffled flask test (BFT). The results indicated a dispersant effectiveness ranging from 47.98 % to 79.76 % for the dispersion of heavy crude oil across various temperature ranges (10-30 °C). These dispersant-to-oil ratios (DOR) were maintained at 3: 100 (V%), showcasing promising dispersant capabilities for mitigating heavy crude oil spills. Additionally, acute toxicity tests conducted on Nile tilapia and Oreochromis niloticus have demonstrated the relatively low toxicity of the IL-dispersants, with Lethal Concentration 50 (LC50) values exceeding 100 ppm after 96 h. This suggests a practically slight toxic effect on the tested fish. In summary, the newly developed IL-dispersants are considered to be conducive to environmentally benign oil spill remediation.

Evaluation of ionic liquids based imidazolium salts as an environmentally friendly corrosion inhibitors for carbon steel in HCl solutions.

The features of this work on corrosion inhibition have been investigated based on the ecological awareness and according to the strict environmental legislations. This was done by studying how different imidazolium derivatives ionic liquids containing different alkyl chains R8, R10 and R12 affected the corrosion reaction of carbon steel specimen immersed in 1 M hydrochloric acid at various temperatures. Weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy were utilized to examine the corrosion inhibition behavior on carbon steel. In addition, FT-IR spectroscopy was used to analyze the coated film that has been formed on the metal surface. The prepared ionic liquids showed effective inhibition efficiency, where the corrosion rate after the using of 100 ppm of R8-IL, R10-IL and R12-IL was decreased from 5.95 (µg cm-2 min-1) to 0.66, 0.56, and 0.44 (µg cm-2 min-1), respectively at 20 °C. In the polarization curves, the corrosion current, Icorr, decreases by ILs addition and suggest that ILs act as mixed type inhibitors. From EIS findings, the increase in Rct and decrease in Cdl values proves the adherence of inhibitor molecules on carbon steel surface. The temperature effect was also studied on the film formed, where increasing the temperature from 20 to 50 °C, the corrosion rate increased and the inhibitors efficacy decreased. The increasing in the length of the attached alkyl chain, the efficacies of the prepared inhibitors increases. Various thermodynamic parameters such as the reaction activation free energy (ΔG*), the entropy of activation (ΔS*), and the enthalpy of activation (ΔH*), as well as the adsorption isotherm were investigated in order to interpret the mechanism and obtain the most accurate perception.

Dicationic ionic liquids (DILs) as rapid esterification catalyst of butyric fatty acid.

In the presented work, a series of asymmetric dicationic ionic liquids (ADILs) with different alkyl chain length spacer between the two cation nuclei (imidazolium and pyridinium) with chlorine halide anion was designed, synthesized with excellent yield (89, 90 and 88%) and well characterized via different tools of analysis (FT-IR and 1H-NMR spectroscopy and thermal gravimetric analysis; TGA). The synthesized ADILs were examined for potential esterification as recyclable catalysts including the activity of catalytic performance, the reaction conditions justifying. The noted resulted data indicated that the butyric acid was converted perfectly into ester in presence of ADILs with short time of reaction. By completing our studies through the effect of chemical structures, concentrations, time and temperatures, we found that the synthesized Py-6-Imi exhibit the best catalytic performance with 96% as conversion value after 20 min at the ambient temperature (25 °C). The synthesized ADILs also recovered and reused for minimum three rounds without any significant reduction in the catalytic performance. Totally, the usage of ADILs in the esterification process offers lots of benefits such as perfect yield, quick time and environmentally friendly characteristics which make them the optimum sustainable compounds to be achieved in variety of industrial applications.

Imidazolium-based ionic liquids as dispersants to improve the stability of asphaltene in Egyptian heavy crude oil.

Deposition of asphaltene aggregates can easily depress the oil production, because it may clog the wellbores, annulus, pipelines, and surface facilities. Moreover, asphaltene molecules have a negative effect on the catalytic reactions in the refinery process. Therefore, in this work, three different ionic liquids (IL-H, IL-CH3, and IL-NO2) were synthesized, and characterized using FT-IR and NMR spectroscopy to evaluate their efficiency as asphaltene dispersants. The thermal gravimetric analysis of the prepared ILs showed that IL-H, IL-NO2, and IL-CH3 were thermally stable up to 280 °C. The ILs showed good dispersion activity of the petroleum asphaltenes, where the asphaltene onset precipitation (AOP) was changed from 7.5 to 10.5, 11, and 13.5 ml added n-heptane after the use of IL-H, IL-NO2, and IL-CH3, respectively. Moreover, the colloidal instability index of crude oil was changed from 0.92 (unstable asphaltene) to 0.69 (stable asphaltene). It is noted during the experiments that the presence of an alkyl chain attached to the ionic liquid moiety increases the efficiency of the dispersant. This may be owing to the formation of π-π* with asphaltene molecules due to the presence of electron donating group. Quantum chemical parameters were calculated for the prepared ILs, and the theoretical data confirmed the experimental results.

Investigation the effect of different ionic liquids based-aryl imidazole on the onset precipitation of asphaltene.

Precipitation and deposition of asphaltene are considered as catastrophic issues facing the petroleum industry. Asphaltene deposition mainly occurs at variety places such as formation pore spaces, pumps, pipelines, wellbore, wellhead, tubing, surface facilities and safety valves causing operational problems, production deficiencies and enormous economic losses. This work aims to study the effect of series of synthesized aryl ionic liquids (ILs) containing different alkyl chains, named as R8-IL, R10-IL, R12-IL, and R14-IL, on the onset precipitation point of asphaltene in crude oil. R8-IL, R10-IL, R12-IL, and R14-IL were synthesized with high yields (the yield varied between 82 and 88%) and characterized via different tools of analysis (FTIR, 1H NMR, and Elemental Analysis). Their Thermal Gravimetric Analysis (TGA) was investigated and showed a reasonable degree of stability. It was found that R8-IL (short alkyl chain) has the highest stability, while R14-IL (long alkyl chain) is the lowest one. Quantum chemical calculations were conducted to study the reactivity and geometry of their electronic structures. Moreover, surface and interfacial tension of them were studied. It was found that the efficiency of the surface active parameters increased by increasing the length of the alkyl chain. The ILs were evaluated to delay the onset precipitation point of asphaltene using to different methods; the kinematic viscosity and the refractive index. Results from the two methods showed delaying of onset precipitation after the addition of the prepared ILs. The asphaltene aggregates was dispersed due to the π-π* interactions and hydrogen bonds formation with the ILs.

Laboratory Experiments on the In Situ Upgrading of Heavy Crude Oil Using Catalytic Aquathermolysis by Acidic Ionic Liquid.

Heavy and extra heavy oil exploitation has attracted attention in the last few years because of the decline in the production of conventional crude oil. The high viscosity of heavy crude oil is the main challenge that obstructs its extraction. Consequently, catalytic aquathermolysis may be an effective solution to upgrade heavy crude oil to decrease its viscosity in reservoir conditions. In this regard, a series of acidic ionic liquids, 1-butyl-1H-imidazol-3-ium 4-dodecylbenzenesulfonate (IL-4), 1-decyl-1H-imidazol-3-ium 4-dodecylbenzenesulfonate (IL-10), and 1-hexadecyl-1H-imidazol-3-ium 4-dodecylbenzenesulfonate (IL-16), were utilized in the aquathermolysis of heavy crude oil. Of each IL, 0.09 wt % reduced the viscosity of the crude oil by 89%, 93.7%, and 94.3%, respectively, after the addition of 30% water at 175 °C. ILs with alkyl chains equal to 10 carbon atoms or more displayed greater activity in viscosity reduction than that of ILs with alkyl chains lower than 10 carbon atoms. The molecular weight and asphaltene content of the crude oil were decreased after catalytic aquathermolysis. The compositional analysis of the crude oil before and after catalytic aquathermolysis showed that the molar percentage of lighter molecules from tridecanes to isosanes was increased by 26-45%, while heavier molecules such as heptatriacontanes, octatriacontanes, nonatriacontanes, and tetracontanes disappeared. The rheological behavior of the crude oil before and after the catalytic aquathermolytic process was studied, and the viscosity of the crude oil sample was reduced strongly from 678, 29.7, and 23.4 cp to 71.8, 16.9, and 2.7 cp at 25, 50, and 75 °C, respectively. The used ILs upgraded the heavy crude oil at a relatively low temperature.

Synthesis and Characterization of Imidazolium-Based Ionic Liquids and Evaluating Their Performance as Asphaltene Dispersants.

With the projected increase in the production of heavy oil due to the energy crisis, asphaltene-related issues are likely to come to the forefront. This leads to operational problems, safety hazards, and oil production deficiencies, resulting in huge economic losses for the petroleum industry. Therefore, in this work, we aimed to inhibit asphaltene precipitation using ionic liquid (IL) compounds. ILs with long alkyl chains can inhibit the precipitation of asphaltene molecules due to the π-π* interactions between them and the formation of hydrogen bonds. A series of imidazolium-based ionic liquids, IL-0, IL-4, IL-10, and IL-16, were synthesized with yield percents of 79, 81, 80, and 83%, respectively. The prepared materials were characterized well using FTIR, 1H-NMR, and Elemental Analysis. The surface tension, interfacial tension (IFT), and different surface parameters were investigated at different temperatures to simulate the reservoir temperature. IL-0, IL-4, IL-10, and IL-16 displayed their γcmc values at 35, 34, 31, and 32 mN/m at 303 °K, respectively. It was found that the prepared ILs are good surfactants with low values of interfacial tension. Quantum structure-activity relationships using Density Functional Theory (DFT) were used to investigate the geometry optimization electronic structures, the energy gap (ΔE), and the reactivity of the cations of the prepared ILs. The synthesized ILs were evaluated as asphaltene dispersants using two different techniques. The viscometric technique showed that the asphaltene onset precipitation was 28.5 vol.%. This percent was postponed to 42.8, 50, 78.5, and 64.3 vol.%, after adding IL-0, IL-4, IL-10, and IL-16, respectively, and the spectroscopic technique confirmed the results.