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 CO2 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 CO2 loading, and 20-100 °C. Experimental results and model predictions show that the high viscosity of high amine concentration (8 m) depresses CO2 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 CO2 absorption rate, high normalized capacity, and negligible solid precipitation.