Piperazine/4-hydroxy-1-methylpiperidine for CO2 capture

Abstract

Aqueous piperazine (PZ)/4-hydroxy-1-methylpiperidine (HMPD) was rigorously evaluated for CO2 capture from flue gas. CO2 cyclic capacity, CO2 absorption rate, solvent viscosity, solvent volatility, and solid solubility were investigated as a function of the solvent composition. 2m PZ/3m HMPD is the composition that offers the best overall performance with more than twice the CO2 cyclic capacity and absorption rate of 7m MEA. This blend also shows much greater resistance to oxidative degradation than MEA at the same conditions, as well as lower amine volatility. When compared to 5m PZ, 2m PZ/3m HMPD has 40% greater CO2 cyclic capacity, 10% slower absorption rate and 10% greater viscosity. 2m PZ/3m HMPD also has much better solid solubility than 5m PZ, with no precipitation down to −10°C in the normal range of CO2 loading. The cost of large-scale production of HMPD was also investigated based on current synthesis routes. The capital and energy cost for flue gas CO2 capture using 2m PZ/3m HMPD is expected to be much lower than 7m MEA, and comparable to 5m PZ.