Experimental and theoretical assessment of the interactions of ionic liquids (ILs) with fluoridated compounds (HF, R-F) in organic medium

Abstract

A liquid-liquid extraction procedure for the removal of fluoridated compounds [i.e., hydrogen fluoride (HF) and organic fluorides (R-F)] from alkylation gasoline (AG) using ionic liquids was studied both experimentally and theoretically. Synthesis and characterization of 1-butyl-3-methylimidazolium bromide, [C4MIM][Br], 1-butyl-3-metylimidazolium trifluoroacetate, [C4MIM][CF3COO], and 1-butyl-3-metylimidazolium bis(trifluoromethanesulphonyl)imide, [C4MIM][NTf2], ionic liquids (ILs) and its evaluation in the adsorption of HF and R-F species from organic medium (AG), was determined experimentally. Also the assessment of molecular interactions of HF with IL in the organic media was studied via Hybrid “QM (quantum mechanics)/MM (molecular mechanics)” Molecular Dynamics (MD) calculations. This QM/MM-MD simulations allowed the setting of a series of time equi-spaced HF-IL system configurations to evaluate interaction energies at QM theoretical level between HF and the closest ILs, as well as the mapping of Non-Covalent Interactions (NCI). Experiments indicate that fluoridated ILs are more efficient for HF extraction than brominated ILs. From the calculated interaction energies and NCI mapping it seems that the capacity of the anion of ILs to form hydrogen bonds with HF is the driving force in HF extraction.