High volumetric uptake in aluminum metal-organic frameworks

Abstract

Methane is the main component of natural gas. Currently there is a great interest in the use of natural gas as fuel for automobiles because of its availability and lower carbon emissions, compared to petroleum. Therefore, there is an extensive work to find materials able to efficiently store and deliver large amounts of methane at operation conditions that can be implemented for on-boards applications. Metal-organic Frameworks, MOFs, are known to be useful in the storage of gases. Here we report the synthesis, crystal structure, porosity and methane adsorption properties of two new aluminum based MOFs, MOF-519, Al8(OH)8(BTB)4(H2BTB)4, and MOF-520, Al8(OH)8(BTB)4(HCOO)4 (BTB = 4,4ʹ,4ʹʹ-benzene-1,3,5-tryil-tribenzoate). Both materials are built from octametallic aluminum SBUs that are linked by the tritopic BTB linker to produce extended three dimensional structures. These structures are highly porous, with Langmuir surface area values of 2660 and 3630 m2 g-1 for MOF-519 and MOF-520, respectively. MOF-519 has the largest total volumetric uptake at 80 bar and 298 K reported for any MOF, being able to store 279 cm3 cm-3. In addition, its working capacity, defined as the amount of methane that can be delivered in the operational pressure range, is 230 cm3 cm-3 between 5-80 bar at 298 K.