The Equilibrium Solubility of Carbon Dioxide in the Mixed Aqueous Solutions of Triisopropanolamine and Monoethanolamine in the Range 30-70 C and Low Partial Pressures

The equilibrium solubility data of CO2 in the various aqueous blends of triisopropanolamine (TIPA) + monoethanolamine (MEA) with the total alkanolamine concentration of 2 mole / dm3 were measured at the temperatures of 30, 40, 50, 60 and 70 oC and CO2 partial pressures below 100 kPa. The experiments were done in an atmospheric gas absorption system and the amount of absorbed CO2 was measured with acidification method and by a graduated burette. The results indicate that the increase in the CO2 partial pressure or the MEA ratio in the blended solvents increases the absorption capacity of the solutions and when the temperature is increased, the capacity decreases. Hence, one can use proper blends of TIPA+MEA to obtain acceptable absorption capacity and lower the regeneration cost and benefit from other useful properties of TIPA such as its low corrosivity and low degradation rate. Immersion corrosion tests carried out on stainless steel 304 coupons at 45 oC for 15 days in some blended solvents, in the presence or absence of dissolved CO2, showed no corrosion.