CO2 capture using highly viscous amine blends in non-porous membrane contactors

New amine blends have shown a promising potential to reduce the energy penalty for CO2 capture in post combustion, making the deployment of carbon capture technologies one-step closer. However, their application at the industrial scale is threaten by their high volatility. Non-porous membrane contactors offer a viable solution to properly control amine emissions from these absorbents. In the present work, the CO2 capture performance of non-porous membrane contactors using new amine blends as liquid phase was investigated in a temperature range typical for the absorption step (25-60 degrees C). Different amine blends with promising features in terms of cycling capacity and regeneration energy requirement were selected as liquid absorbents. Thin composite membranes fabricated by coating a perfluoropolymer on the top of a porous polypropylene layer were used as the interface between the gas and the liquid. At room temperature, membrane contactors using new absorbents exhibit a lower CO2 mass transfer coefficient compared to the benchmark (30 wt% MEA), possibly due to the high viscosity of these liquids. The modelling analysis suggests that the liquid boundary layer dominates the mass transfer resistance in the temperature range up to 40 degrees C, but at higher temperatures, the decrease of the solvent viscosity makes the mass transfer dominated by the membrane phase. Interestingly, the new amine blends show better performance compared to the benchmark at higher CO2 concentrations in feed gas, highlighting a good potential to capture CO2 from concentrated flue gas from steel/cement industry or to upgrade biogas.