We report the molecular design of antiscaling chemicals based on carboxylic acids and sulfonate random copolymers focused in avoiding the formation of CaCO3 particles to be applied in oil fields ...having high salinity and high hardness such as those of Mexican reservoirs. Density functional theory calculations reveal that the studied antiscaling chemicals inhibit the growth of calcite particles, undo the previously formed ones, and capture the CaCl2 salt units. This functionality is due to antiscaling chemicals having a marked trend for reacting with CaCO3 units to form bicarbonate anions. In particular, the random copolymer whose backbone contains itaconic acids and sodium vinyl sulfonates in a 4:1 molar ratio is a better antiscaling chemical than the one having a 1:1 molar ratio because adjacent itaconic acids’ carboxylic heads act together to form chelating bindings with the formed bicarbonates. Likewise, these random copolymers overcome the scale-inhibiting performance of commercial products based on phosphonates. The experimental static and dynamical antiscaling tests, as well as the scanning electron microscopy images confirm the theoretical predictions.
Density Functional Theory based studies about the inhibition of corrosion affecting the cathode hematite surface by coverage with an methylimidazole-based ionic liquid, IL, were performed. Inhibition ...performance is tuned through the length of aliphatic chains C n attached to the imidazolium aromatic ring, where n = 1, ..., 20. Frontier molecular orbitals and energy gaps for single ILs and a pristine (11̅2) hematite surface, the energy difference between ILs and hematite-surface, Fukui indices for the ILs, and adsorption energies and charge transfers for ILs/hematite surface systems were calculated. Results show that adsorption activity is due to the donation/back-donation bonding among the imidazolium aromatic ring of the ILs and the exposed iron atoms of the hematite surface. Dispersive long-range interactions from the ILs alkyl tails allow a closer bonding of the corrosion inhibitor molecules to the hematite surface; the charge transfer between the IL and the hematite is in C18. The optimal alkyl chain size is 18 and this is in full agreement with the reported experimental alkyl chain size that produces high inhibitory properties of related vinylimidazolium ILs.
A Gaussian chain model of poly (styrene)−poly (isoprene) (PS−PI) block copolymer with a dissipative particle dynamics (DPD) simulation was employed to study the formation of specific characteristic ...structures such as body-centered-cubic (BCC), hexagonal packed cylinders (HPC), ordered bicontinuous double diamond (OBDD), and lamellar (LAM) via order−disorder transition (ODT). The BCC, HPC, OBDD and LAM microphases were then subjected to thermal cycles of heating and cooling. The order−order phase transition (OOT) from HPC to BCC was monitored and two new transitions, OBDD to LAM and LAM to hexagonal perforated layers (HPL), were detected during the thermal process. Two metastable states (cylinders and HPL) were observed in the OOT process from the OBDD to LAM microphases. It is shown that all order−order transitions between the different kinds of structures are thermoreversible. The results were compared with the predictions of recent theories and with available experimental outcomes and thus provide a test for the predictions of BCC, OBDD, and LAM microphases.
The interaction between ethanethiol molecule and either anhydrous FeIII chloride anions or 1-butyl-3-methylimidazolium (BMIM+) cations of ionic liquids (ILs) was investigated using Density Functional ...Theory approach and results were correlated with our previous experimental results on extractive desulfurization (EDS), where ILs containing anionic FeIII species show excellent performance to remove sulfur compounds from natural gasoline, especially when there exists an excess of FeCl3 in the BMIM+FeCl4− IL since this mixture contains binuclear anions Fe2Cl7−, whose Fe―Cl―Fe bonds are larger and less strong than Fe―Cl bonds of mononuclear anions FeCl4−, being then the former bonds activated for ethanethiol chemisorption. Molecular frontier orbitals and Mulliken atomic charges reveal that the high desulfurization performance could be due to a Dewar–Chatt–Duncanson-like mechanism of electron donation–backdonation among ethanethiol sulfur and transition metal centers of Fe2Cl7− anions, and this mechanism is promoted because of the symmetry affinity among the ethanethiol HOMO and the atomic orbital t2g on Fe sites in Fe2Cl7− LUMO. On the other hand, when there is no excess of FeCl3, EDS increases with the size of N-alkyl substitutes in BMIM+ due to ethanethiol physisorption by these cations.
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► DFT study of desulfurization of ionic liquids containing FeIII. ► Interaction between ionic liquids containing Fe and ethanethiol was investigated. ► Dewar–Chatt–Duncanson-like mechanism can explain our experimental results.
Ionic conductivity of crosslinked chitosan membranes was studied using techniques of molecular modeling and simulation. The COMPASS force field was used. The simulation allows the description of the ...mechanism of ionic conductivity along the polymer matrix. The theoretical results obtained are compared with experimental results for chitosan membranes. The analysis suggests that the conduction mechanism is portrayed by the overlapping large Polaron tunneling model. In addition, when the chitosan membrane was crosslinked with an appropriate degree of crosslinking its ionic conductivity, at room temperature, was increased by about one order of magnitude. The chitosan membranes can be used as electrolytes in solid state batteries, electric double layer capacitors and fuel cells.
Oil production and maintenance are essential issues in naturally fractured reservoirs because they are the largest and most productive on earth. However, they present early water and gas channeling ...but could be remediated by using foaming agents to control these phenomena through blocking channeling areas. In Mexico these reservoirs have pressure up to 5,500 psi, high temperature up to 200 °C, salinity up to 400,000 ppm, and hardness up to 250,000 ppm; due to these thermodynamic conditions, there has been no available technology to form stable enough foams. In this work, a foaming supramolecular surfactant with the capability to chelate Ca2+ ions is examined. As a result, surfactant monomers are bridged by captured Ca2+ cations leading to the formation of high-molecular-weight oligomers, which significantly increment the viscosity of the solution improving the foam stability, and since at this manner the Ca2+ cations are no longer available to precipitate as components of solid salts, the foaming supramolecular surfactant also performs as antiscalant. These observations are explained through quantum theoretical modeling. The foam is stable, effectively blocking the gas channels, whereas in presence of oil the foam is broken leading the oil to pass into the wellbore. The characteristic rheological properties of the foam allow its injection into the formation at a range of flow rates, foam qualities, and shear stress to achieve the flooding and the blocking of a variety of fractured carbonate formations, and the change of the wettability of the matrix, which is a desirable behavior in a huff and puff process, as reported in a previous publication about a successful pilot test of this foam.
Mesoscopic simulations of linear and 3-arm star poly(styrene)−poly(isoprene) block copolymers was performed using a representation of the polymeric molecular structures by means of Gaussian models. ...The systems were represented by a group of spherical beads connected by harmonic springs; each bead corresponds to a segment of the block chain. The quantitative estimation for the bead−bead interaction of each system was calculated using a Flory−Huggins modified thermodynamical model. The Gaussian models together with dissipative particle dynamics (DPD) were employed to explore the self-organization process of ordered structures in these polymeric systems. These mesoscopic simulations for linear and 3-arm star block copolymers predict microphase separation, order−disorder transition, and self-assembly of the ordered structures with specific morphologies such as body-centered-cubic (BCC), hexagonal packed cylinders (HPC), hexagonal perforated layers (HPL), alternating lamellar (LAM), and ordered bicontinuous double diamond (OBDD) phases. The agreement between our simulations and experimental results validate the Gaussian chain models and mesoscopic parameters used for these polymers and allow describing complex macromolecular structures of soft condensed matter with large molecular weight at the statistical segment level.
N-aryl amino-alcohols as stabilizers of asphaltenes Chávez-Miyauchi, Tomás Eduardo; Zamudio-Rivera, Luis S.; Barba-López, Victor ...
Fuel (Guildford),
08/2013, Letnik:
110
Journal Article, Conference Proceeding
Recenzirano
► N-aryl amino-alcohols were synthesized and evaluated as asphaltene stabilizers. ► Boronic acid compounds showed good efficiency as asphaltene aggregation inhibitors. ► Asphaltene aggregation ...inhibition was confirmed by flocculation kinetics. ► Boronic acid compounds showed also viscosity reducing effect of a heavy crude oil. ► Aggregation and interaction mechanisms were studied via molecular modeling.
A new class of N-aryl amino alcohols were designed, synthesized and evaluated as asphaltene aggregation inhibitors–dispersants. Structures of all compounds were corroborated by FTIR, 1H, 13C, 11B NMR and Mass Spectroscopy. The boronic acid moiety was included into the structure of the amino-alcohols because it presents low acidic Brönsted character but a good effectiveness as Lewis acid, feature which is assumed important in the interaction with asphaltenes. Boron based compounds are believed to form tetrameric complexes due to spectrometric evidence, in addition, they showed good efficiencies as asphaltene aggregation inhibitors, which was confirmed by flocculation–precipitation kinetics and rheological behavior experiments. Molecular modeling was used to analyze the aggregation mechanisms among asphaltenes and the interactions between them and amino-alcohols. Because of an outstanding agreement between theoretical and experimental results, a mechanism of interaction between the chemical compounds and asphaltenes is proposed.
•Enhanced oil recovery (EOR) through tetraalkylammonium chloride (C12TAC) flooding.•Theoretical and experimental researches of the ion–dipole supramolecular assembly between C12TAC and ...1-naphtol.•Screening charge densities (SCD) and molecular orbital analyses for the interacting molecules.•Supramolecular assembly is driven by the charge-donor and -acceptor SCD peaks matching.
Ion–dipole pair formations driven by supramolecular interactions between the dodecyltrimethylammonium chloride (C12TAC) cationic surfactant and either 1-naphthol (NAP), quinoline (QN) or benzothiophene dipolar molecules, which model heteroaromatic ring groups displayed by asphaltenes and resins contained in heavy Mexican crude oils, were theoretically and experimentally analyzed. Theoretical studies on supramolecular interactions, in vacuum and chloroform environment, were performed via Density Functional Theory (DFT) approach. Interaction energies, screening charge densities (SCDs) and molecular orbitals for ion–dipole pairs, reveal that the strongest supramolecular interaction shown by the C12TAC:NAP complex is due to fully matching among charge-donor and charge-acceptor SCD peaks of C12TAC and NAP, respectively, overriding the interaction among C12TAC and the most-dipolar molecule, QN. The supramolecular synthesis of the NAP:C12TAC ion–dipole pairs were carried out, and then 13C NMR chemical shifts were measured relative to the standard tetramethylsilane, confirming the supramolecular complex formation through the position difference of the carbon signals between pure and assembled NAP. It was found that carbon-signal assignment, performed through a theoretical-experimental data correlation, is best achieved when conformations of C12TAC and NAP molecules, as well of their C12TAC:NAP complex, are obtained in chloroform, in which NMR measurements were done, instead of vacuum.
Zwitterionic liquids have a wide variety of applications in enhanced oil recovery (EOR). In particular, geminal zwitterionic substances have been used as wettability modifiers of limestone, ...dolomites, and sandstones at high temperatures and pressures. The understanding of the interaction mechanisms of such molecules with the limestone surface is an important step toward the comprehension of the modification in wettability. In the study here presented, the interaction energies of limestone with geminal zwitterionic liquids of the type bis-N-alkyl polyether were calculated within the framework of the density functional theory (DFT). With the use of the DMOL3 library of the Material Studio Software (a DFT-based computational code), we calculated the interaction energies of the bis-N-alkyl polyether liquids, asphaltene with the limestone rocks.
