Scalable fabrication of amine-functionalized microgel composite membranes and their gas permeation characteristics

Post-combustion carbon dioxide (CO2) separation from exhaust gases is a bridge technology to reduce the emissions of traditional combustion processes. Primary amine-functionalized building blocks enhance the CO2 selectivity of membranes via a facilitated transport mechanism. Microgels are polymer-based colloids that can be functionalized with amine groups. However, to serve as a successful membrane building block, high aminesloading, and a scalable fabrication route are necessary. Here, we report the continuous synthesis of amine-functionalized microgels and apply them as a dense selectivity layer to form thin-film composite membranes (TFC). The synthesis process was successfully scaled up from batch to laminar flow reactor, producing microgels containing up to 50 mol% amine incorporation. Amine incorporation influences microgel water uptake important for their gas separation properties. Porous polyacrylonitrile (PAN) membranes containing a spray-coated microgel layer are tested using a mixture of CO2 and N2, with or without humidity in the feed stream. Both CO2 permeance and selectivity increase with the amine content in the microgels and the moisture in the feed stream. At 95% relative humidity, the CO2 permeance improved from 38 to 100 GPU when the amine incorporation rose from zero to 48% of 2-aminoethyl methacrylate (AEMA). The continuous synthesis allows large-scale fabrication of these microgels for applications such as membrane functionalization. Furthermore, the developed microgel-functionalized gas separation membranes are promising for CO2 removal applications from high-humidity streams, such as flue gas.