Investigation of CO₂ Capture in Nonaqueous Ethylethanolamine Solution Mixed with Porous Solids

Abstract

In this work, the postcombustion CO₂ capture performance was explored in 100.000 g of a nonaqueous solution, 30 wt % monoethylethanolamine (EMEA) and 70 wt % diethylethanolamine (DEEA). Porous solids (multiwalled carbon nanotubes (MWCNTs), silica gel (SG), and MCM-41) with mass fractions (0.025, 0.050, 0.100 and 0.200%) were added into the pure nonaqueous solution forming the new absorbents to improve the CO₂ capture performance. The CO₂ absorption (313 K) and desorption (383 K) of the new absorbents were operated in the absorption–desorption apparatus under atmospheric pressure. The results show that the addition of the porous solids in the nonaqueous solution led to a 2% decrease in the absorption loading, while contributing to a 10 min decrease in the desorption time under the same desorption extent. The maximum desorption rates of the new absorbents peaked about 5 min earlier than that of the nonaqueous solution, with an enhancement order of MWCNTs > MCM-41 > SG. Meanwhile, the new absorbent, nonaqueous solution mixed with 0.050% MWCNTs, had the best enhancement in the desorption process and exhibited a good stability in the absorption–desorption experiment. Analytic methods (XRD, BET, FT-IR, and SEM) were used to characterize MWCNTs before and after the five absorption–desorption cycles, which showed a good stability of MWCNTs with no significant change in the structure and activity