Incorporation of Alkylamine into Metal Organic Frameworks through a Bronsted Acid Base Reaction for CO2 Capture.
The escalating atmospheric CO2 concentration is one of the most urgent environmental concerns of our age. To effectively capture CO2 various materials have been studied. Among them, alkylamine modified metal organic frameworks (MOFs) are considered to be promising candidates. In most cases, alkylamine molecules are integrated into MOFs through the coordination bonds formed between open metal sites (OMSs) and amine groups. Thus, the alkylamine density, as well as the corresponding CO2 uptake in MOFs, are severely restricted by the density of OMSs. To overcome this limit, other approaches to incorporating alkylamine into MOFs are highly desired. We have developed a new method based on Bronsted acid base reaction to tether alkylamines into Cr MIL 101 SO3 H for CO2 capture. A systematic optimization of the amine tethering process was also conducted to maximize the CO2 uptake of the modified MOF. Under the optimal amine tethering condition, the obtained tris(2 aminoethyl)amine functionalized Cr MIL 101 SO3 H (Cr MIL 101 SO3 H TAEA) has a cyclic CO2 uptake of 2.28 mmol g 1 at 150 mbar and 40 degC, and 1.12 mmol g 1 at 0.4 mbar and 20 degC. The low cost starting materials and simple synthetic procedure for the preparation of Cr MIL 101 SO3 H TAEA suggest that it has the potential for large scale production and practical applications.
ChemSusChem