Tailoring piperazine-based phase change absorbents with low viscosity for energy-efficient CO2 capture

CO 2 phase change absorbents (CPCA) have attracted significant interest as potential candidates for the high-efficiency capture of CO 2 . However, the high viscosity of the rich phase in CPCAs hinders their broader application. Given the exceptional CO 2 capture performance and cyclic stability of piperazine (PZ), this study focuses on developing a PZ-based CPCA system of PZ/ n -BuOH/H 2 O to reduce solution viscosity and regeneration energy consumption. Experimental results reveal that the viscosity of the rich phase in PZ/ n -BuOH/H 2 O is as low as 7.06 mPa·s, while the regeneration energy consumption is 2.64 GJ·t −1 CO 2 , which is 19.8 % lower than in the conventional PZ/H 2 O system. Furthermore, 13 C NMR analysis and density functional theory (DFT) calculations provide insight into the CO 2 capture process and mechanism of PZ/ n -BuOH/H 2 O, indicating that polarity differences are primarily responsible for phase separation. Overall, the CPCA of PZ/ n -BuOH/H 2 O developed in this study evinces considerable potential for industrial CO 2 capture applications.