Accurate screening of amines by the Wetted Wall Column

Abstract To screen amine solvents accurately for CO 2 capture, a Wetted Wall Column (WWC) was used to measure equilibrium CO 2 partial pressure and CO 2 absorption/desorption rate at variable CO 2 loading from 40 to 100 °C. The solvents included 10 m diglycolamine (DGA ® ), 4.8 m 2-amino-2-methyl-propane (AMP), 8 m N-methyl-1,3-propanediamine (MAPA), 7 m/2 m and 5 m/5 m methyldiethanolamine (MDEA)/piperazine (PZ). With a semi-empirical VLE model assuming a lean/rich CO 2 loading corresponding to 500 Pa/5000 Pa CO 2 partial pressure, cyclic capacity and heat of CO 2 absorption was determined. Liquid film mass transfer coefficients are reported for each solvent, which allows estimation of packing area required for 90 removal via a simple absorber design. The results show that the capacity of DGA ® and MAPA is 10–20% less than 7 m MEA with a 5 to 15% slower rate. 4.8 m AMP has a capacity twice as great as 7 m MEA, but the rate is lower by 45%. 7 m/2 m MDEA/PZ has a similar capacity to 8 m PZ but slightly slower rate. 5 m /5 m MDEA/PZ has a capacity 20% greater than 8 m PZ and a comparable rate. The heat of CO 2 absorption in the primary amines is about 80 kJ/mol CO 2 . The value for PZ and its blend with MDEA is about 70 kJ/mol CO 2 .

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