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

The huge energy penalty of CO desorption is the greatest challenge impeding the commercial application of amine-based CO capture. To deal with this problem, a series of metal oxide and oxyhydroxide catalysts were synthesized in this study to kinetically facilitate the CO desorption from 5.0 M monoethanolamine (MEA). The effects of selected catalysts on CO absorption kinetics, CO absorption capacity, CO 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 desorption. The kinetic study of catalytic CO desorption was also carried out. CO 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 absorption kinetics and CO reaction enthalpy of MEA. In contrast, the CO desorption efficiency greatly increased from 28% in reference MEA to 52% in ZrO(OH)-aided MEA. Compared to the benchmark catalyst HZSM-5, ZrO(OH) exhibited a 13% improvement in CO desorption efficiency. More importantly, compared to the reference MEA, the CO desorption duties of ZrO(OH) 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) and FeOOH afforded the catalytic performance by promoting the adsorption of alkaline speciation (e.g., MEA and HCO ) onto the particle surface.