Improving the absorption load, high viscosity, and regeneration efficiency of CO2 capture using a novel tri-solvent biphasic solvents of TETA-AMP-1DMA2P.

Abstract

Currently, biphasic solvents are receiving more attention for CO2 capture due to their energy-saving potential. Whereas, most of the current biphasic solvents still suffer from high viscosity and low regeneration efficiency. To solve this problem, a novel tri-solvent biphasic solvent triethylenetetramine (TETA)-2-amino-2-methyl-1-propanol (AMP)-1-dimethylamino-2-propanol (1DMA2P) was proposed in this study, and its absorption properties, viscosity changes, desorption properties, recyclability capacity, and reaction mechanism were explored. The results showed that the CO2 absorption load showed a trend of firstly increasing and then decreasing with the increase of AMP concentration. Although the volume of the rich phase increased with increasing AMP concentration after the absorption, it also decreases the viscosity growth. The viscosity of the solution decreased from 498mPa•s to 91mPa•s. During the desorption process, the maximal desorption rates of AMP-containing solvents is significantly greater than that of 2mol/L (M) TETA + 2M 1DMA2P (2T2D). Simultaneously, the recyclability capacity of the AMP-containing solvents were also significantly higher than that of 2T2D. The regeneration efficiency of 1.5M TETA + 0.5M AMP + 2M 1DMA2P (1.5T0.5A2D) was 81.92%. It was concluded by 13C NMR analysis that amino groups in TETA and AMP can react with CO2 to form carbamates and carbonates. Since AMP in the biphasic solution can generate free protons through various pathways during the desorption process, it promotes the decomposition of TETA-carbamate. This process achieves the deep stripping of CO2 in biphasic solvent. Overall, TETA-AMP-1DMA2P solution is a promising energy-saving candidate for industrial CO2 capture due to its competitive absorption-desorption performance and low viscosity.