Recent developments of deep eutectic solvent as absorbent for co₂removal from syngas produced from gasification: Current status, challenges, and further research

Gasification has been increasingly seen as a method to convert solid fuel into combustible syngas. However, these applications require syngas with strict requirements and raw syngas often does not meet these requirements. Therefore, a form of syngas upgrading needs to be applied. One of the most common form of syngas upgrading is removal of CO2, which is often present in large concentrations in raw syngas. The currently existing CO2 removal technologies were either designed not with syngas in mind or for large scale industries, which makes them somewhat inefficient for application with gasification syngas. This calls for more research into efficient removal of CO2, from syngas. In this review, the application of deep eutectic solvent (DES) as one of the potential new absorbent for CO2 removal from gas streams and more specifically from syngas are discussed. DES has garnered attention due to its high CO2 absorption performance, process friendliness, and environmental friendliness. At present, most studies on DES are still limited to basic absorption behavior of the absorbent. This review aims to provide not just a clear picture of the current research situation for DES as CO2 removal absorbent, but also detail the possible research directions that might be taken for the development of DES as CO2 absorbent from syngas. To that end, this paper shall discuss the specific situation of gasification development, syngas utilization, and the current DES research situation including: its advantages compared to conventional absorbents, its current research situation, challenges, and possible future research directions.