Facilitated transport of CO2 through immobilized liquid membrane

Selective removal of acid gases from a contaminated gas stream was studied using four amines (diethylenetriamine (DETA), diaminoethane (DAE), diethylamine (DEYA), and bis(2-ethylhexyl)amine (BEHA)) as immobilized liquids in a facilitated transport membrane. The effect of amine concentration, CO2 partial pressure, and operating temperature on the permeance of CO2 and CH4 was investigated for each aqueous amine solution. The observed CO2 permeance decreased with increasing CO2 feed pressure, whereas the permeance of CH4 remained constant for all tested amines. The permeance Of CO2 and the selectivity were in the order DETA > DAE > BEHA approximate to DEYA. This order is related to the number of nitrogen atoms per amine molecule, which can be correlated to loading capacity and consequently to amine reactivity with CO2. The permeance Of CO2 in 2 M DETA increased with increasing temperature. The permeance of CO2 using DETA was about 4 times that obtained using diethanolamine (DEA) and monoethanolamine (MEA), which are the most commonly used solvents in industrial applications.