Extractive desulfurization of liquid hydrocarbon fuel using ionic liquids: Cationic and anionic selection through Principal Component Analysis and experimental study

Abstract

Extractive desulfurization using ionic liquids has gained more attraction due to simplicity and easy operating conditions of sulfur compounds removal from liquid hydrocarbon fuels. But the selection of proper cations and anions are still the most challenging parts of all researches. In the present study, a new methodology was developed for screening of cation and anion molecules to obtain maximum sulfur removal efficiency. At first, the best structural descriptors were selected using Genetic algorithm. The different kinds of 1D, 2D and 3D molecular descriptors for a diverse library of cation/anion have been evaluated, including 114 cations and 48 anions. Then, the most proper cations and anions have been selected using Principal Component Analysis (PCA) after evaluating the most accurate structural descriptors for various cations and anions. It was concluded that ionic liquids (ILs) comprise imidazolium and pyridinium cations with hexyl chain, combined with the [N(CN)2] and [Ac] anions, are promising ILs as extraction solvents for extractive desulfurization. To evaluate the obtained results, one of the selected ILs, 1-Hexyl-3-methyl pyridinium dicyanamide ([HMPY][N(CN)2]), has been examined and has been synthesized for the first time as extractant for EDS. The synthesized IL was examined through NMR and FTIR analysis. After that by investigating results and the slope of tie-lines, distribution coefficient, selectivity and the capability of selected IL to sulfur removal of DBT or BT in both phases, it is observed that [HMPY][N(CN)2] is a proper solvent for extraction of DBT or BT from n-heptane.