Measuring the Absorption Rate of CO 2 in Nonaqueous CO 2 ‐Binding Organic Liquid Solvents with a Wetted‐Wall Apparatus

The kinetics of the absorption of CO 2 into two nonaqueous CO 2 ‐binding organic liquid (CO 2 BOL) solvents were measured at T =35, 45, and 55 °C with a wetted‐wall column. Selected CO 2 loadings were run with a so‐called “first‐generation” CO 2 BOL, comprising an independent base and alcohol, and a “second‐generation” CO 2 BOL, in which the base and alcohol were conjoined. Liquid‐film mass‐transfer coefficient ( k ′ g ) values for both solvents were measured to be comparable to values for monoethanolamine and piperazine aqueous solvents under a comparable driving force, in spite of far higher solution viscosities. An inverse temperature dependence of the k ′ g value was also observed, which suggests that the physical solubility of CO 2 in organic liquids may be making CO 2 mass transfer faster than expected. Aspen Plus software was used to model the kinetic data and compare the CO 2 absorption behavior of nonaqueous solvents with that of aqueous solvent platforms. This work continues our development of the CO 2 BOL solvents. Previous work established the thermodynamic properties related to CO 2 capture. The present paper quantitatively studies the kinetics of CO 2 capture and develops a rate‐based model.