Post-Combustion CO2 Capture Capacity Enhanced by Incorporation of Task Specific Ionic Liquid into ZIF-8

Abstract

In this present work, a task specific ionic liquid (TSIL) was encapsulated into the framework of ZIF-8 to enhance its CO2 capture capacity and CO2/N2 selectivity at post-combustion conditions. 1-Ethyl-3-methylimidazolium amino-acetate [EMIM][Gly] was selected as TSIL. TSIL@ZIF-8 composite sorbents were prepared by varying the loading of TSIL and the sorbents’ thermal stability, porous structure and crystal nature were investigated. Incorporation of TSIL into ZIF-8 has shown dramatic impact on CO2 uptake especially at below 1.0 bar. At this low-pressure range, CO2 uptake was higher than the pristine ZIF-8 for all TSIL loadings. TSIL@ZIF-8 composite with 30 wt.% TSIL reached a CO2 uptake capacity of 0.55 mmol·g-1 at 0.2 bar which was 6 times higher than the pristine ZIF-8 at the same condition. TSIL incorporated composites also exhibited much higher selectivity than the pristine ZIF-8 at all studied pressures. CO2/N2 ideal selectivity at 313 K for 30 wt.% [EMIM][Gly] loading was 28 and 19 at 0.1 and 0.2 bar, respectively. This composite sorbent with significantly higher CO2 uptake and better CO2/N2 selectivity at low pressure region (<1.0 bar) can play an important role in post-combustion CCS processes.

Keywords: CO2 Capture, Task-Specific Ionic Liquid (TSIL), Metal Organic Framework (MOF), ZIF-8