Deep eutectic solvents for CO2 capture from natural gas by energy and exergy analyses

Abstract

Nowadays, environmental issues and the energy crisis are among the most important challenges to researchers. The necessity of increasing the energy efficiency of industrial processes is vital. If this efficiency increase is additionally done by using sustainable components, environmental issues are also alleviated. Deep eutectic solvents (DESs) are a new generation of green solvents with unique properties. This has led to the exponential growth of research in the field, oriented towards green chemistry and green processing. This study investigates the feasibility of utilizing DESs in the petroleum industries by considering the case study of capturing CO2 from natural gas, resulting in a purified gas with greater heating value. The idea is to utilize the DES as an absorbent, in place of the conventional Selexol. The pressure swing absorption process was simulated for two different DES, namely Reline and Glyceline. The purity of the methane stream was 89.1% when using Selexol, and 90.1% and 79.6% for Reline and Glyceline, respectively. The carbon dioxide stream showed even greater purity differences when DESs were used (98.3%, 98.4% and 94.9% CO2 when using Reline, Glyceline, and Selexol, respectively). Furthermore, energy and exergy analyses were carried out on the proposed plants. While the overall duties were less for the plants using DESs (−51.27, −11.13, and 15.17 and kW for Reline, Glyceline, and Selexol, respectively), the exergy destructions were not (146.78, 165.64, 96.54 kW for Reline, Glyceline, and Selexol, respectively). The results indicated the feasibility of using DESs as potential physical solvents in such industries.