Effects of Viscosity on CO2 Absorption in Aqueous Piperazine/2-methylpiperazine

Abstract 2-methylpiperazine (2MPZ) and equimolar 2-methylpiperazine/piperazine (PZ) blends are attractive as they preserve most of the benefits of PZ and overcome its limitations of solid solubility. The CO 2 absorption rate and vapor liquid equilibrium (VLE) of 4 m 2MPZ and 2.5 m/2.5 m 2MPZ/PZ were measured using the wetted wall column. Using the Aspen Plus ® eNRTL framework, thermodynamic and kinetics models of 2MPZ and 2MPZ/PZ were built with 2 m to 8 m amine, 0.15-0.4 CO 2 loading, and 20-100 °C. Experimental results and model predictions show that the high viscosity of high amine concentration (8 m) depresses CO 2 absorption rate and normalized capacity. 5 m 2MPZ and 2.5 m/2.5 m 2MPZ/PZ are competitive solvents for amine scrubbing because of high CO 2 absorption rate, high normalized capacity, and negligible solid precipitation.