Microporous polymers are currently being studied for a range of different applications including molecular separation in gas or liquid phase, catalysis, and water treatment. Their porosities are related to highly crosslinked structures or inherently large free volumes. These polymers can exhibit large or even very large surface areas and micropore or mesopore volumes, where micropores are < 2 nm and mesopores between 2-50 nm.
We present findings on micro- and mesoporous polymers designed to separate CO2 from gas mixtures with either physisorption or chemisorption. Separation of CO2 is important in Carbon Capture and Storage (CCS) as well as in biogas or natural gas upgrading. Possibilities to tune the microporosity and mesoporosity with chemical methods and means to modify them with aliphatic amines will be highlighted. Such aliphatic amines are shown to act as chemisorbents with high heats of adsorption of CO2 (Qst) and are relevant to capturing CO2 from streams with low concentrations of CO2. Physisorbents, with their comparably low Qst, are more relevant to CO2 separation when the gas mixture has a high concentration of CO2. Open questions concerning the price of the polymers and potential advantages as compared with other types of adsorbents, or membranes, will be discussed.
In addition, recent findings on porous polymers derived from platform molecules of biorefineries will be presented. The platform molecules were polymerized, very rapidly, at close to ambient temperatures, and the formed solids/polymers had specific surface areas with values close to 1000 m2/g. One such composition displayed a surprisingly high Qst value of 42-44 kJ/mol, which is important for the CO2-over-N2/CH4 selectivity.