Direct Access to Primary Amines and Particle Morphology Control in Nanoporous CO₂ Sorbents

Chemical tuning of nanoporous, solid sorbents for ideal CO₂ binding requires unhindered amine functional groups on the pore walls. Although common for soluble organics, post-synthetic reduction of nitriles in porous networks often fails due to insufficient and irreversible metal hydride penetration. In this study, a nanoporous network with pendant nitrile groups, microsphere morphology was synthesized in large scale. The hollow microspheres were easily decorated with primary amines through in situ reduction by widely available boranes. The CO₂ capture capacity of the modified sorbent was increased to up to four times that of the starting nanoporous network with a high heat of adsorption (98 kJ mol^-1 ). The surface area can be easily tuned between 1 and 354 m²  g^-1 . The average particle size (ca. 50 μm) is also quite suitable for CO₂ capture applications, such as those with fluidized beds requiring spheres of micron sizes.