Currently available gas separation materials have limitations, including poor chemical and thermal stability under practical CO₂ capture processes, low CO₂ uptake and/or high CO₂ uptake with additional energy requirement at the desorption step, low CO₂ separation performance over other gasses present in the gas stream, high energy output to release capture CO₂, and complex material design and preparation processes.

This invention describes the design, synthesis, and use of a new polymeric sorbent (polybenzimidazole, BILP-101) for CO₂ capture and separation from mixed gas streams. The polymer is synthesized using a template-free polycondensation reaction between commercially available aryl aldehyde and amine-based monomers. Evaluation of BLIP-101 under realistic test conditions demonstrated a sorbent material with exceptional CO₂ uptake/working capacity, high CO₂ selectivity, as well as superior chemical and thermal stability. The simplified fabrication process will allow for easier commercial scale up at an overall lower production cost. Furthermore, while the neat BILP-101 is a strong physical sorbent, reactivity of the material can be tuned for stronger interaction with CO₂ as a chemical sorbent. Possible applications for this technology may include CO₂ capture from fossil fueled power plants, natural gas sweetening, biogas updgrading, and CO₂ removal from cabin air for life support systems.