Non‐dispersive absorption of CO 2 in parallel and cross‐flow membrane modules using EMISE

BACKGROUND: This paper reports an analysis of the mass transfer behaviour of CO 2 absorption in hollow fibre membrane modules in parallel and cross‐flow dispositions. The ionic liquid EMISE, 1‐ethyl‐3‐methylimidazolium ethylsulfate, is used to achieve a zero solvent emission process and the experimental results are compared with CO 2 permeation through the membrane, without solvent in the lumenside. RESULTS: Overall mass transfer coefficients K overall , CF = (0.74 ± 0.02) × 10 −6 m s −1 and K overall , PF = (0.37 ± 0.018) × 10 −6 m s −1 were obtained for cross‐flow and parallel flow, respectively. These values are one order of magnitude lower than the coefficient obtained in permeability experiments, K overall , PERM = (6.16 ± 0.1) × 10 −6 m s −1 , indicating the influence of the absorption in the process. Including the specific surface and gas volume of each contactor in the analysis, a similar value of a first‐order kinetic rate constant, K R = 2.7 × 10 −3 s −1 is obtained, showing that the interfacial chemical reaction CO 2 ‐ionic liquid is the slow step in the absorption process. CONCLUSION: An interfacial chemical reaction rate constant K R = 2.7 × 10 −3 s −1 , describes the behaviour of the CO 2 absorption in the ionic liquid EMISE using membrane contactors in parallel and cross‐flow dispositions. Copyright © 2012 Society of Chemical Industry