Pushing the limits of intensified CO2 post-combustion capture by gas–liquid absorption through a membrane contactor

• Membrane contactors can be operated with concentrated (up to 90 wt%) MEA solutions.
• Intensification factor is maximal for a 70% MEA concentration at 60 °C.
• Membrane mass transfer coefficient should be larger than 10−4 m s−1.
• Happel’s model provides a very good prediction of shell side pressure drop.
• The volume of the absorption unit and the energy penalty can be decreased with membrane contactors.

The possibility to maximize the intensification (i.e., volume reduction) of post-combustion carbon dioxide capture by chemical absorption in a monoethanolamine (MEA) solution using a membrane contactor module is reported. The influence of MEA concentration (20–90 wt%) and temperature (293–333 K) on the CO2 capture ratio achieved by a PTFE hollow fiber membrane contactor has been investigated with a CO2/N2 (15/85 vol%) gas mixture and the experimental results modeled. It is shown, through a systematic parametric analysis, that the intensification factor of the absorption unit, defined as the ratio of the CO2 volumetric absorption capacity of the membrane contactor and of the packed column (taken at 1 mol CO2 m−3 s−1), can be largely increased when a concentrated (70 wt%) MEA solution at 333 K is used. A volume reduction up to a factor 9, together with a lower energy penalty due to pressure drop effects (kWh per ton of captured CO2) is potentially obtained compared to packed column performances, when a large enough membrane mass transfer coefficient is achieved (i.e., larger than 10−4 m s−1). The remaining challenges which are required in order to develop this level of performances at industrial scale based on the existing membrane contactor materials are discussed.

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