Highly efficient CO2 capture using 2-methylimidazole aqueous solution on laboratory and pilot-scale

Abstract

To date, the primary industrial carbon capture approach is still absorption using aqueous solutions of alkanolamines. Here, to pursue a substitute for the amine-based approach to improve the CO2 capture efficiency and decrease the energy cost further, we report a new carbon capture approach using a 2-methylimidazole (mIm) aqueous solution. The properties and sorption behaviors of this approach have been experimentally investigated. The results show that the mIm solution has higher CO2 absorption capacity under relatively higher equilibrium pressure (>130 kPa) and lower desorption heat than the methyldiethanolamine solution. 91.6% sorption capacity of mIm solution can be recovered at 353.15 K and 80 kPa. The selectivity for CO2/N2 and CO2/CH4 can reach an exceptional 7609 and 4324, respectively. Furthermore, the pilot-scale tests were also performed, and the results demonstrate that more than 98% of CO2 in the feed gas could be removed and cyclic absorption capacity can reach 1 mol·L–1. This work indicates that mIm is an excellent alternative to alkanolamines for carbon capture in the industry.