Aluminum formate, Al(HCOO) ₃ : An earth-abundant, scalable, and highly selective material for CO ₂ capture

A combination of gas adsorption and gas breakthrough measurements show that the metal-organic framework, Al(HCOO) 3 (ALF), which can be made inexpensively from commodity chemicals, exhibits excellent CO 2 adsorption capacities and outstanding CO 2 /N 2 selectivity that enable it to remove CO 2 from dried CO 2 -containing gas streams at elevated temperatures (323 kelvin). Notably, ALF is scalable, readily pelletized, stable to SO 2 and NO, and simple to regenerate. Density functional theory calculations and in situ neutron diffraction studies reveal that the preferential adsorption of CO 2 is a size-selective separation that depends on the subtle difference between the kinetic diameters of CO 2 and N 2 . The findings are supported by additional measurements, including Fourier transform infrared spectroscopy, thermogravimetric analysis, and variable temperature powder and single-crystal x-ray diffraction.