Performance and Mechanisms of Triethylene Tetramine (TETA) and 2-Amino-2-methyl-1-propanol (AMP) in Aqueous and Nonaqueous Solutions for CO2 Capture

Nonaqueous amines are currently being explored for energy-efficient postcombustion CO2 capture, but the absorption capacity and regeneration efficiency of most absorbents still need to be further improved. In this work, a mixture of triethylene tetramine (TETA) and 2-amino-2-methyl-1-propanol (AMP) dissolved in ethanol was chosen as a nonaqueous absorbent for CO2 capture and performed with high absorption loading and regeneration efficiency. In addition, the changes of the components during the absorption–desorption process and reaction mechanisms of nonaqueous absorbents were explored by 13C NMR spectroscopy and compared with those of aqueous absorbents. The results showed that TETA/AMP/ethanol had higher absorption loading and regeneration efficiency (3.71 mol kg–1, 95.4%) after the fifth regeneration cycle than TETA/AMP/water (3.54 mol kg–1, 38.8%) when the amine mass concentration was 40 wt %. CO2 capture by TETA/AMP aqueous and nonaqueous solutions proceeded by two different mechanisms. Polycarbamate...