Vapor-assisted self-conversion of basic carbonates in metal-organic frameworks

Incorporation of nanoparticles has been considered as an efficient method for enhancing the adsorption performance of metal-organic frameworks (MOFs). Alkali metal compounds possess outstanding affinity to acidic CO 2 . In this study, a robust self-conversion strategy is reported for improving the carbon capture performance of MOFs, through directly transforming partial metal centers to basic carbonate (BC) nanoparticles. Based on the hydrolysis of coordination bonds induced by water impurity in solvents and the decarboxylation of linkers under thermal and alkaline conditions, the self-loading of BC in MOFs can be realized by solvent vapor-assisted thermal treatment. Since water impurity causes limited self-conversion and excess organic solvent can purify MOFs, the BC-MOF materials maintain good crystallinity and even show superior porosity. Owing to the increased specific surface areas, open metal sites, and alkalinity of BC, the prepared MOF composites exhibit substantially improved CO 2 capture performance with good balance between capacity and selectivity. For example, after self-conversion with ethanol solvent, the CO 2 adsorption capacity and CO 2 /N 2 (15 : 85) selectivity at 298 K and 100 kPa increase from 3.7 mmol g −1 and 11.4 to 5.8 mmol g −1 and 29.2, respectively. Basic carbonates with high alkalinity are incorporated into metal-organic frameworks by solvent vapor-assisted self-conversion of partial metal centers to improve carbon capture performance.