Evaluating CO₂-Desorption Performance of Solid Acid Catalysts in CO₂-Loaded Aqueous Solutions of N-Ethylethanolamine

Abstract

Postcombustion CO2 capture will be more attractive if the regeneration energy constraint of amine-based solvents is lowered. Metal oxides catalyze CO2 desorption, thus resulting in efficient amine regeneration. The catalytic regeneration of the N-ethylethanolamine (EEA) solvent was investigated in this study using 10 commercially available metal oxide catalysts. Batch trials were performed with EEA (2.5 M) in a glass apparatus at T = 368 K. The initial CO2 loading was in the 0.32–0.35 mol CO2/mol EEA range. The impact of different catalysts on the regeneration process was evaluated. The catalysts improved the efficiency of CO2 desorption over its value in blank EEA in the following order: Al2O3 (167%) > CuO (104%) > MnO2 (101%) > V2O5 (96%) > TiO2 (65%) > ZnO (61%) > Cr2O3 (50%) > SiO2 (49%) > MgO (46%) > ZrO2 (40%). The effect of changing Al2O3 catalyst loading (between 3 and 12 g Al2O3/400 mL solution) on the desorption features of EEA (1.67 M) was insignificant. It was found that Al2O3 enabled desorption at lower temperatures (338 K) and reduced the sensible energy constraint by 38%. For the case when ZrO2 was impregnated with SO4 2–, the CO2 desorption efficiency increased in addition by 15% and sensible energy consumption decreased by 25%.