Metal Oxyhydroxide Catalysts Promoted CO 2 Absorption and Desorption in Amine-Based Carbon Capture: A Feasibility Study.

The huge energy penalty of CO 2 desorption is the greatest challenge impeding the commercial application of amine-based CO 2 capture. To deal with this problem, a series of metal oxide and oxyhydroxide catalysts were synthesized in this study to kinetically facilitate the CO 2 desorption from 5.0 M monoethanolamine (MEA). The effects of selected catalysts on CO 2 absorption kinetics, CO 2 absorption capacity, CO 2 reaction enthalpy, and desorption duty reduction of 2.0 M MEA were investigated by a true heat flow reaction calorimeter to access the practical feasibility of the catalytic CO 2 desorption. The kinetic study of catalytic CO 2 desorption was also carried out. CO 2 desorption chemistry, catalyst characterization, and structure-function relationships were investigated to reveal the underlying mechanisms. Results show that addition of the catalyst had slight effects on the CO 2 absorption kinetics and CO 2 reaction enthalpy of MEA. In contrast, the CO 2 desorption efficiency greatly increased from 28% in reference MEA to 52% in ZrO(OH) 2 -aided MEA. Compared to the benchmark catalyst HZSM-5, ZrO(OH) 2 exhibited a 13% improvement in CO 2 desorption efficiency. More importantly, compared to the reference MEA, the CO 2 desorption duties of ZrO(OH) 2 and FeOOH-aided MEA significantly reduced by 45 and 47% respectively, which are better than those of most other reported catalysts. The large surface area, pore volume, pore diameter, and amount of surface hydroxyl groups of ZrO(OH) 2 and FeOOH afforded the catalytic performance by promoting the adsorption of alkaline speciation (e.g., MEA and HCO 3 - ) onto the particle surface.