Impact of post-synthesis modification of nanoporous organic frameworks on small gas uptake and selective CO2 capture

Abstract

Porous organic polymers containing nitrogen-rich building units are among the most promising materials for selective CO₂ capture and separation applications that impact the environment and the quality of methane and hydrogen fuels. In this study, we report on post-synthesis modification of nanoporous organic frameworks (NPOFs) and its impact on gas storage (H₂, CH₄, CO₂) and selective CO₂ binding over N₂ and CH₄ under ambient conditions. The synthesis of NPOF-4 was accomplished via acid catalyzed cyclotrimerization reaction of 1,3,5,7-tetrakis(4-acetylphenyl)adamantane in ethanol/xylenes. NPOF-4 is microporous and has high surface area (SA_BET = 1249 m² g⁻¹). Post-synthesis modification of NPOF-4 by nitration afforded NPOF-4-NO₂ and its subsequent reduction resulted in an amine-functionalized framework NPOF-4-NH₂ that exhibits improved gas storage capacities and very high CO₂/N₂ (139) and CO₂/CH₄ (15) selectivities compared to NPOF-4.