Deciphering the Sustainability of an Ionic Liquid-Based BTX Harvesting Process from Energetic, Environmental, and Economic Perspectives

1-Ethyl-3-methylimidazolium bis[(trifluoromethyl)-sulfonyl]imide ([EMIM][Tf2N]) ionic liquid as a novel absorbent has excellent performance in BTX absorption. However, compared with the traditional method using triethylene glycol (TEG), the sustainability of the former is unknown. Thus, to bridge the gap and give a comprehensive evaluation of its industrialization potential, a methodology-integrated energetic, economic, and environmental assessment was employed. The assessment results show that the heating and cooling energy consumptions of the TEG process are 1.08 and 0.74 times higher than those of the [EMIM][Tf2N] process, respectively. But through heat integration, 5% hot and 3.4% cold utilities can be saved for the [EMIM][Tf2N] process. In terms of economic performance, the total annual costs for TEG and [EMIM][Tf2N] processes are 0.6111 and 0.4841 M$/year, respectively, and the latter is 26.3% lower than the former. As for the environmental assessment, the results indicated that compared with the TEG scenario, the [EMIM][Tf2N] scenario without absorbent recovery presented higher environmental burdens in all categories, and the largest difference lies in acidification, for which the latter is 42 times that of the former. However, when considering the absorbent recovery, the results are contradictory. Thus, the comprehensive assessment methodology proved that the [EMIM][Tf2N]-based BTX absorption process is sustainable and can be a potential industrialization technology.