Quantum chemical insights and continuum solvation predictions on the dissolution of bituminous and anthracite coal in Ionic Liquid

The current work reports the ab initio calculations on Ionic Liquids (ILs) with bituminous and anthracite coal particles using both Density Functional Theory (DFT) and solvation predictions using COnductor like Screening MOdel for Real Solvents (COSMO-RS) model. The commercial cations used in the study were 1-butyl-1-methylpyrrolidinium ([BMPYR]), 1-methyl-3-propylimmidazolium ([MPIM]), Tributylmethylammonium ([TMA]) and Tributylmethylphosphonium ([MTBP]). The corresponding anions were methyl carbonate ([CH3CO3]), dicyanamide ([N(CN)(2)]), bis(trifluromethylesulfonyle)imide ([Tf2N]) and methylsulfate ([MeSO4]). A three-tier approach comprising of HOMO-LUMO energies, quantum descriptors (electronegativity, electrophilicity, global hardness, global softness); and Infinite Dilution Activity Coefficient (IDAC) by COSMO-RS model were chosen for studying the simultaneous interaction. 1-butyl-1-methylpyrrolidinium methylcarbonate [BMPYR][CH3CO3] and 1-methyl-3-propylimmidazolium methylcarbonate [MPIM][CH3CO3] were the recommended IL's on the basis of HOMO-LUMO band energy gap. A similar trend for IL-coal interactions were followed up and confirmed by the quantum descriptors and IDAC predictions. A direct correspondence between reported swelling ration and excess Gibb's energy has also been attempted. (C) 2016 Elsevier B.V. All rights reserved.