Thermally Degraded Diglycolamine^®/Dimethylaminoethoxyethanol for CO₂ Capture

Thermally degraded diglycolamine^® (DGA^®)/dimethylaminoethoxyethanol (DMAEE) was found to have a better performance for CO₂ capture than the fresh, undegraded solvent. At high temperature, DGA^®/DMAEE reaches equilibrium with its major degradation product, methylaminoethoxyethanol (MAEE). The production of MAEE enhances the CO₂ absorption rate, while maintaining the CO₂ capacity of the original solvent. The normalized CO₂ cyclic capacity of DGA^®/MAEE/DMAEE is substantially greater than that of 7 m monoethanolamine (MEA) and 10 m DGA^®, and comparable to 5 m piperazine (PZ). The average CO₂ absorption rate of DGA^®/MAEE/DMAEE is 30-70% higher than 7 m MEA, although it is still much lower than 5 m PZ. The heat of CO₂ absorption (ΔH_abs) for 1.75 m DGA^®/1.75 m MAEE/3.5 m DMAEE at CO₂ loading corresponding to P_CO2∗of 1.5 kPa at 40 °C is 72 kJ/mol, which is comparable to 7 m MEA, and greater than 5 m PZ. Published by Elsevier Ltd.