Phase-changing solution PZ/DMF for efficient CO2 capture and low corrosiveness to carbon steel

In order to reduce energy consumption of absorbent regeneration, an amine absorbent piperazine (PZ) was dissolved in an organic solvent N, N-dimethylformamide (DMF) to prepare a phase-changing PZ/DMF solution for CO2 absorption with solid precipitate of PZ-carbamate. The CO2 absorption capacity and peak rate of PZ/DMF solution were 22.9% and 29% higher than those of PZ/water solution, respectively. Based on differential scanning calorimetry/thermogravimetry experiments, biscarbamate PZ(CO2)22− and protonation PZ(H)22+ compositions (34.5 wt%) in the PZ-carbamate precipitate mainly decomposed at peak temperature of 91.9 °C due to their instability, and then PZ(CO2) composition (65.5 wt%) in the PZ-carbamate precipitate decomposed at peak temperature of 125.7 °C. The electrochemical corrosion tests and scanning electron microscopy revealed that PZ/DMF solution had much lower corrosivity than PZ/water solution.