Non‐dispersive absorption of CO2 in parallel and cross‐flow membrane modules using EMISE

BACKGROUND: This paper reports an analysis of the mass transfer behaviour of CO2 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 CO2 permeation through the membrane, without solvent in the lumenside. RESULTS: Overall mass transfer coefficients Koverall, CF = (0.74 ± 0.02) × 10−6 m s−1 and Koverall, 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, Koverall, 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, KR = 2.7 × 10−3 s−1 is obtained, showing that the interfacial chemical reaction CO2‐ionic liquid is the slow step in the absorption process. CONCLUSION: An interfacial chemical reaction rate constant KR = 2.7 × 10−3 s−1, describes the behaviour of the CO2 absorption in the ionic liquid EMISE using membrane contactors in parallel and cross‐flow dispositions.