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

Currently, biphasic solvents are receiving more attention for CO 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 CO 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 498 mPa•s to 91 mPa•s. During the desorption process, the maximal desorption rates of AMP-containing solvents is significantly greater than that of 2 mol/L (M) TETA + 2 M 1DMA2P (2T2D). Simultaneously, the recyclability capacity of the AMP-containing solvents were also significantly higher than that of 2T2D. The regeneration efficiency of 1.5 M TETA + 0.5 M AMP + 2 M 1DMA2P (1.5T0.5A2D) was 81.92%. It was concluded by C NMR analysis that amino groups in TETA and AMP can react with CO 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 CO in biphasic solvent. Overall, TETA-AMP-1DMA2P solution is a promising energy-saving candidate for industrial CO capture due to its competitive absorption-desorption performance and low viscosity.