CO₂ Desorption in Single and Blended Amine Solvents with and without Catalyst

In this work, various single and blended amines (namely, MEA, MEA-DEEA, MEA-MDEA, MEA-1DMA2P) with three types of catalysts (H-ZSM-5, MCM-41 and SO₄^2-/ZrO₂) were studied to determine the respective roles of catalyst and solvent in heat duty for solvent regeneration and rate of CO₂ desorption during the desorption of CO₂ from the solvents having an initial CO₂ loading of 0.5 mol CO₂/mol amine at 371 K. The results show that performance of the three catalysts in all the four investigated aqueous solution systems followed the trend: H-ZSM-5 > MCM-41 > SO₄^2-/ZrO₂. These results highlight the fact that even though HZSM-5 has moderate acidic sites (MAS) as compared to MCM-41 and SO₄^2-/ZrO₂, its large Brønsted/Lewis (B/L) acid sites ratio coupled with mesopore surface area (MSA) had the greatest effect on heat duty for CO₂ desorption as well as rate of CO₂ desorption. Furthermore, based on this study, the blended system of aqueous 5 M MEA+1 M MDEA with H-ZSM-5 provided the best approach for solution regeneration because the strong electron withdrawing chemical structure of MDEA made the solution most prone to CO₂ desorption as compared with 1DMA2P and DEEA.