(111g) Measurement of Liquid Film Mass Transfer Coefficients for CO2-Binding Organic Liquids (CO2BOLs)

Zheng, R., Pacific Northwest National Lab
Koech, P. K., Pacific Northwest National Laboratory
Bearden, M., Pacific Northwest National Lab
Freeman, C. J., Pacific Northwest National Laboratory
Valkenburg, C., Pacific Northwest National Laboratory
Heldebrant, D. J., Pacific Northwest National Laboratory

CO2 absorption kinetics of a CO2BOL solvent were measured using a wetted-wall column.  The solvent was a DBU-hexanol two-component first-generation CO2BOL.  Liquid film mass transfer coefficients were obtained at 35, 45, and 55°C near atmospheric pressure and three CO2 loading levels at each temperature: 0.5, 1.0, and 4.4 wt% (gram of CO2 per gram of unloaded solvent).  The corresponding molar loading levels were 4.5, 9.7, and 43%.  On the basis of equal CO2 molar loadings, the data were compared with 5M MEA literature data.  Compared to 5M MEA at 40°C and 60°C, at the same molar solvent loading, DBU-hexanol has a larger equilibrium CO2 pressure P* and lower liquid film mass transfer coefficient (k’g) values.  The general similarity in liquid film mass transfer coefficients (k’g) between MEA and CO2BOLs allows for projections of CO2BOL equipment sizing and costing similar to NETL Case 10 baseline for coal-fired powerplants.  Bench-scale testing of CO2BOLs are currently ongoing to provide definitive data on mass transfer for better process economics projections.  In this presentation, the above results on the first-generation CO2BOL kinetics will be discussed.  Experimental challenges in making accurate WWC measurements on an anhydrous solvent will also be discussed.