Liquid-liquid equilibria and mechanism exploration for the extraction of sulfides from FCC naphtha via organic solvent as extractant

Hydrocarbon Extraction with Ionic Liquids

Separation and reaction processes are key components employed in the modern chemical industry, and the former accounts for the majority of the energy consumption therein. In particular, hydrocarbon separation and purification processes, such as aromatics extraction, desulfurization, and denitrification, are challenging in petroleum refinement, an industrial cornerstone that provides raw materials for products used in human activities. The major technical shortcomings in solvent extraction are volatile solvent loss, product entrainment leading to secondary pollution, low separation efficiency, and high regeneration energy consumption due to the use of traditional organic solvents with high boiling points as extraction agents. Ionic liquids (ILs), a class of designable functional solvents or materials, have been widely used in chemical separation processes to replace conventional organic solvents after nearly 30 years of rapid development. Herein, we provide a systematic and comprehensive review of the state-of-the-art progress in ILs in the field of extractive hydrocarbon separation (i.e., aromatics extraction, desulfurization, and denitrification) including (i) molecular thermodynamic models of IL systems that enable rapid large-scale screening of IL candidates and phase equilibrium prediction of extraction processes; (ii) structure-property relationships between anionic and cationic structures of ILs and their separation performance (i.e., selectivity and distribution coefficients); (iii) IL-related extractive separation mechanisms (e.g., the magnitude, strength, and sites of intermolecular interactions depending on the separation system and IL structure); and (iv) process simulation and design of IL-related extraction at the industrial scale based on validated thermodynamic models. In short, this Review provides an easy-to-read exhaustive reference on IL-related extractive separation of hydrocarbon mixtures from the multiscale perspective of molecules, thermodynamics, and processes. It also extends to progress in IL analogs, deep eutectic solvents (DESs) in this research area, and discusses the current challenges faced by ILs in related separation fields as well as future directions and opportunities.

In-depth unveiling the interfacial adsorption mechanism of triazine derivatives as corrosion inhibitors for carbon steel in carbon dioxide saturated oilfield produced water

In this work, two triazine derivatives (BTT-1 and BTT-2) were synthesized by the simple one-step condensation of three components and used as high-efficient corrosion inhibitors to deal with the corrosion issue of carbon steel (CS) in petroleum industry. Electrochemical tests indicate that both BTT-1 and BTT-2 present superior inhibition performance with the inhibition efficiency of 97.9 % and 98.4 % at a low concentration of 0.18 mM, respectively. Quantum chemical calculations reveal that compared to BTT-1 molecule with a butyl chain, the introduction of benzyl group endows BTT-2 molecule with more adsorption sites, which favors the adsorption of BTT-2 molecule on CS surface. Furthermore, the GFN-xTB calculations demonstrate that BTT-1 and BTT-2 could adsorb on CS surface through the formation of Fe-N and Fe-S bonds. Compared to BTT-1, BTT-2 exhibits stronger adsorption on CS surface by forming more and shorter bonds with a more negative adsorption energy, which accounts for the better inhibitive performance of BTT-2.

Sulfolane as a novel stationary phase for analytical separations by gas chromatography

Sulfolane is explored as a novel stationary phase for use in analytical separations by capillary column gas chromatography with flame ionization detection (GC-FID). Stainless steel capillaries were found to provide a good substrate for coating and retaining a sulfolane phase, whereas fused silica tubing did not perform well for this. In general, the phase was found to be stable for several hours of use when using elevated carrier gas pressures (90 psi) and a small restriction (25 μm I.D. tubing) at the outlet. This normally provided good performance at temperatures up to about 200 °C with very little background interference in the FID. Given its separation properties, a short 2 m × 100 μm I.D. column was found to be preferable for most separations in this study. Measurements indicated the coating procedure yielded a sulfolane film near 4 μm thick on this column, which produced 4400 plates for benzene with a sample capacity near 30 μg. The sulfolane phase yielded good retention and peak shape for many analytes including alkanes, aromatics, alcohols, bases, sulfides, phosphites, thiols, and others. Compared to longer conventional GC columns, the relatively short sulfolane column was found to offer improved selectivity in the separation of unsaturated, aromatic, and alkane test analytes. As such the method was successfully applied to the analysis of aromatics in gasoline headspace. Results suggest that sulfolane could be a potentially useful stationary phase to further explore in GC separations.