Fabrication of microporous polymers for selective CO₂ capture: The significant role of crosslinking and crosslinker length

Owing to their high physicochemical stability, low skeletal density, tailorable surface properties, and high porosity, microporous crosslink polymers are highly promising for selective CO₂ capture, separation, and storage. The crosslinking (CL) and crosslinker length (CLL) in a polymer play a quite significant role in enhancing selective CO₂ capture. To investigate the role of CL and CLL, polymers with no crosslinking (non-crosslinking, NCL), and small-(SCL), and long-crosslinker lengths (LCL) were successfully fabricated. It is noteworthy that the polymer containing SCL has remarkable CO₂ adsorption capacity and selectivity over the polymer with LCL and NCL. High selectivity for CO₂ over CH₄/N₂ was observed in the sequence SCL > LCL > NCL. This indicates that not only CL but CLL is also significantly important in generating highly efficient adsorbents. The adsorption capacity reaches 208.3 mg g^-1, which is higher than that of the benchmarks including activated carbon (122.8 mg g^-1), and 13X zeolite (180.3 mg g^-1), as well as most reported carbon-based adsorbents. The CO₂/N₂ and CO₂/CH₄ selectivity reaches 541.4 and 64, respectively. Moreover, excellent recyclability was observed without loss in CO₂ adsorption for 10 cycles. Thus, high CO₂ capture, excellent selectivity, and high recyclability under energy-saving mild regeneration conditions make microporous polymers a unique adsorbent for selective CO₂ capture from flue gas and natural gas.