Poly-amino-based ionic liquids coupled with semi-coke for biogas upgrading

Abstract Poly-amino-based ionic liquid (IL) [TETAH] + [BF 4 ] - was mixed with sodium hydroxide solution for CO 2 separation from biogas in a spray scrubber packed with modified semi-coke. A CO 2 absorption capacity of 0.92mol was achieved when controlling the outlet CO 2 concentration below 3 vol%. The porous structure of semi-coke contributed to improving CO 2 absorption. Nitric acid oxidation and heat treatment could increase the specific surface area, enlarge the intrinsic pores and develop more micropores. Semi-coke firstly oxidized by nitric acid and then with heat treatment could not only exhibit higher specific surface area and more porous structure, but also show less degree of graphitization, which was suggested as possible to increase the reactivity to CO 2 . It was assumed that the absorption system in this research showed promising application in CO 2 separation from biogas as well as waste treatment.