Experimental and Theoretical Study on Supramolecular Ionic Liquid (IL)-Asphaltene Complex Interactions and Their Effects on the Flow Properties of Heavy Crude Oils.

A combined study for understanding the molecular interactions of asphaltenes with molecular species such as ionic liquids (ILs) comprised experimental measurements and computational numerical simulation calculations, using density-functional theory (DFT) with dispersion corrections, molecular dynamics (MD) calculations, and experimental rheological characterization of the heavy crude oils (HCOs), before and after doping with ILs, respectively. The main results show that ILs influence the asphaltenic dimer association by forming supramolecular complexes that modify the properties of crude oils such as viscosity and interfacial tension. The IL-cation and asphaltene-π ligand molecular interactions seem to dominate the interactions between ionic liquids and asphaltenes, where ILs' high aromaticity index induces a strong interaction with the aromatic hard core of asphaltenes.

Molecular design of high performance zwitterionic liquids for enhanced heavy-oil recovery processes.

Branched gemini zwitterionic liquids, which contain two zwitterionic moieties of linked quaternary-ammonium and carboxylate groups, are proposed as chemicals to be applied in the Enhanced Oil Recovery (EOR) from fractured carbonate reservoirs. The zwitterionic moieties are bridged between them through an alkyl chain containing 12 ether groups, and each zwitterionic moiety has attached a long alkyl tail including a CC double bond. A theoretical molecular mechanism over which EOR could rest, consisting on both the disaggregation of heavy oil and the reservoir-rock wettability alteration, was suggested. Results show that chemicals can both reduce the viscosity and remove heavy-oil molecules from the rock surface.

Theoretical study of a new group of corrosion inhibitors.

In the present work, the molecular interactions of four amino acid compounds were simulated through the density functional theory (DFT) indexes to study their inhibitive properties. The prototype inhibitors previously synthesized 2-amino-N-decylacetamide (G), 2-amino-N-decylpropionamide (A), 2-amino-N-decyl-3-methylbutyramide (V), and 2-amino-N-decyl-3-(4-hydroxyphenyl)propionamide (T) were used to test the accuracy of this calculation. The generalized gradient approximation (GGA) was the ab initio approach used to optimize the ground state of the molecules. The simulation of molecular dynamics with force field (AMBER) was calculated to obtain the interaction energy between the metallic surface and the inhibitor molecules. A strong correlation of the global and local indexes with the inhibiting capacity was observed. The inhibitive properties of compounds on mild steel in an aqueous hydrochloric acid solution agreed well with those derived from the reactivity and selectivity indexes in gaseous phase.

A theoretical study of dibenzothiophene absorbed on open-ended carbon nanotubes.

The (7,7) and (10,5) carbon nanotubes were studied in the context of the Density Functional Theory (DFT) within a generalized gradient approximation (GGA). The Becke's exchange functional along with the correlation functional of Lee, Yang, and Parr (BLYP) were used with the DZVP basis set aided via auxiliary functions for the electron density. In both materials, the global indexes were calculated from the optimized structure with Kopmanns' theorem. The energy values calculated for the physisorption and chemisorption processes suggested that the physisorption process is more likely to occur for the (7,7) than for the (10,5) carbon nanotube, as well as for the achiral than chiral structure for both nanotubes and for both surface phenomena. This effect may be ascribed to the more homogeneous distribution of molecular orbital for the achiral carbon nanotube, which seems to be supported by the DOS calculations.