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

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 (SABET = 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.