Integrated CO<sub>2</sub> Capture and Mineralization Based on Monoethanolamine and Lime Kiln Dust
Liang Li, Hai Yu, Graeme Puxty, Song Zhou, William Conway, Paul Feron
Abstract
High Resolution Image Download MS PowerPoint Slide Development and deployment of innovative and cost-effective CO 2 capture and utilization technologies can not only reduce the amount of CO 2 currently in or being emitted into the atmosphere but also develop a circular economy and deliver economic growth. Differing from previous studies on amine-based CO 2 capture in isolation, the work herein is focused on an integrated CO 2 capture and mineralization approach with monoethanolamine (MEA) as CO 2 liquid absorbent and utilization of lime kiln dust (LKD) as the CO 2 mineralization feedstock to regenerate or recover MEA used for CO 2 capture. Aqueous solutions containing 2.0 M MEA were used to capture CO 2 from a simulated flue gas comprising a CO 2 concentration of 10.0% (by volume) prior to the addition of LKD powders to precipitate captured CO 2 in the MEA solution through carbonation reactions. Following CO 2 mineralization, MEA filtrate was collected and analyzed by FTIR and ICP-OES, with solid materials undergoing chemical analysis by TGA and SEM, and additionally for particle size. The CO 2 mineralization process was found to be significantly influenced by the solution pH and temperature of the MEA absorbent solution, where conditions below pH 10.5 restrained CO 2 mineralization due to the limited availability of carbonate ions. Conversely, under higher pH conditions, the conversion of carbamate and bicarbonate to carbonate is promoted, accelerating the CO 2 mineralization process. Increasing the absorbent temperature (i.e., from 40.0 to 60.0 °C) resulted in a corresponding and considerable increase in the CO 2 mineralization rate and the CO 2 desorption efficiency of MEA. Following mineralization, the CO 2 desorption efficiency of CO 2 -loaded MEA reaches 79–83%. The CO 2 sequestration capacity of LKD was determined to be ∼230 g CO 2 per kg, with calcite and aragonite forms as the major calcium carbonate products formed during the CO 2 mineralization processes.