Evaluating Energy-Efficient Solutions of CO<sub>2</sub> Capture within Tri-solvent MEA+BEA+AMP within 0.1+2+2–0.5+2+2 mol/L Combining Heterogeneous Acid–Base Catalysts
Huancong Shi, Xuan Yang, Hongliang Feng, Junxing Fu, Ting Zou, Jiayue Yao, Zimeng Wang, Linhua Jiang, Paitoon Tontiwachwuthikul
Abstract
To reduce the extensive energy penalty of CO2 desorption process of amine-based CO2 capture technology, the combination of “coordinative effect” with “heterogeneous catalysis” was adopted into “MEA+BEA+AMP” tri-solvents at special concentrations (0.1–0.5+2+2 mol/L) with solid base catalysts “CaCO3” and various solid acid catalysts “γ-Al2O3, H-ZSM-5, and blended γ-Al2O3/H-ZSM-5”. Experiments were performed to evaluate if there were synergetic effects within the optimization of amine blend concentrations and catalyst selections. Reaction schemes were investigated within the tri-solvents to understand the absorption and desorption mechanisms of coordinative effect. CO2 absorption was performed at 40 °C, and CO2 desorption was performed at 90 °C. Five tri-solvent compositions with various catalysts were investigated in terms of initial absorption rate (Iabs), initial desorption rate (Ides), heat duty (H), and cyclic capacities, which were categorized into absorption–desorption parameters systematically. The results indicated that tri-solvents with catalysts were highly energy-efficient. The optimized tri-blend was 0.3+2+2 mol/L MEA+BEA+AMP, which performed better than the 2+2 mol/L BEA+AMP benchmark on both absorption and desorption. The optimized regeneration performance of tri-blends was 0.3+2+2 mol/L, and its relative heat duty was 32.9% of that of 5 M MEA and 66.5% of that of 2+2 M BEA+AMP. Results manifested that the combination of solid acid–base catalysts with tri-solvents containing “coordinative effects” was a promising solution to further optimize the energy efficiency of CO2 absorption–desorption within industrial amine-based CO2 capture processes.