Aqueous Ethylenediamine for CO2 Capture

Aqueous ethylenediamine (EDA) has been investigated as a solvent for CO2 capture from flue gas. EDA can be used at 12 M (mol kg(-1) H2O) with an acceptable viscosity of 16 cP (1 cP = 10(-3) Pa s) with 0.48 mol CO2 per equivalent of EDA. Similar to monoethanolamine (MEA), EDA can be used up to 120 degrees C in a stripper without significant thermal degradation. Inhibitor A will effectively eliminate oxidative degradation. Above 120 degrees C, loaded EDA degrades with the production of its cyclic urea and other related compounds. Unlike piperazine, when exposed to oxidative degradation, EDA does not result in excessive foaming. Over much of the loading range, the CO2 absorption rate with 12 M EDA is comparable to 7 M MEA. However, at typical rich loading, 12 M EDA absorbs CO2 2 times slower than 7 M MEA. The capacity of 12 m EDA is 0.72 molCO(2)/(kg H2O+EDA) (for P-CO2 = 0.5 to 5 kPa at 40 degrees C), which is about double that of MEA. The apparent heat of CO2 desorption in EDA solution is 84 kJ mol(-1) CO2; greater than most other amine systems.