Abstract
This paper evaluates the thermodynamic efficiency of a newly synthesized large-scale pre-combustion CO2 capture process using a novel ionic liquid (IL) 1-octyl-2,3-methylimidazolium thiocyanate [OMMIM][SCN] for blue H2 production. In addition, the potential eco-toxicity of the selected IL was assessed using the ADMETlab 2.0 web tool. The results of these analyses were compared to those of an established IL 1-butyl-2,3-dimethylimidazolium bis(trifluoromethyl sulfonyl)imide [BMMIM][TF2N]. The eco-toxicity assessment confirmed that [OMMIM][SCN] is less environmentally toxic than [BMMIM][TF2N]. Thermodynamic analysis of the novel system shows the COOLER unit accounts for the highest energy demand; however, the [OMMIM][SCN] system demonstrates a 7.45% reduction in energy consumption in the COOLER unit compared to [BMMIM][TF2N]. The system experienced the highest exergy losses (irreversibilities) in the COOLER unit for [BMMIM][TF2N] (12982 kW) and in the flash separator unit for [OMMIM][SCN] (8256 kW). The thermodynamic efficiency was analyzed within a specified IL inlet temperature range (25oC – 75oC) and absorption pressure range (7 - 16 bar). The results show that the [OMMIM][SCN] system outperforms [BMMIM][TF2N] with higher IL inlet temperature but decreases at higher absorption pressure, while [BMMIM][TF2N] maintains constant energy efficiency. The exergy efficiency of the [OMMIM][SCN] system shows better performance across the studied conditions but decreases beyond the peak temperature range of 50–60°C. These findings highlight the potential of [OMMIM][SCN] as an excellent alternative solvent for pre-combustion CO2 capture applications.