Selection of ionic liquid for extraction processes: Special case study of extractive desulfurization

Abstract

Selecting of appropriate ionic liquids (ILs) as extracting agents is a key to ensuring an extraction process. Therefore, this study illustrates a systematic method for an extractive desulfurization (EDS) process to select the most promising ILs. The proposed method combines: 1) COSMO-RS calculation of the mutual solubility of ILs and fuel oil, and the capacity of ILs for the S-compounds, 2) experimental investigation of the prescreened ILs for their desulfurization ability, 3) and Aspen Plus simulation of developing a new insight into the industrial application of EDS. Based on the obtained results, [C1pyr][H2PO4] and [C1pyr][HSO4] having small mutual solubility with fuel oil, high extraction capacity for S-compounds and high desulfurization efficiency are selected as two promising ILs. Considering the qualification of the low sulfur content standard and real industrial applications, [C1pyr][H2PO4] is recognized as the most favorable solvent for the EDS process. The proposed method initiating from micro-level to experimental stage and finally to industrial stage can preferably be extended over a variety of extraction application for selection of the promising ILs.