Cation exchange in an anionic nanoporous MOF for study of CO2 adsorption

Developing new materials for CO2 capture and separation is becoming more vital as intensive combustion of fossil fuels has increased CO2 concentration in the atmosphere [1]. Metal Organic Frameworks (MOF) have regular accessible cages that can be used for selectivity adsorbing CO2 increasing the MOF pore volume and surface area [2] or modifying the pore chemistry to increase CO2 capacity [3]. In this study we focused on CO2 adsorption capacity in an anionic MOFs of [HDMA]2[Zn2(BDC)3(DMA)2].6DMF (TMU-3) Fig.1, BDC2-: 1,4-benzenedicarboxilate, DMA: dimethylamine and DMF: N,N -dimethylformamide) by modifying their pore volumes.For such purpose we exchanged [NH2Me2]+ (dimethylammonium) with series of organic cations such as tetramethylammonium, tetraethylammonium, tetrapropylammonium and tetrabutylammonium, and studied the effect of these exchanges on their BET surface area and CO2 adsorption capacity. The exchanged materials were also characterized by IR,1H-NMR spectroscopies and by TG-DTA and XRD analyses.The SEM images of ZnO nanostructures which were assembled by direct calcination of the exchanged MOFs were reported too.