CO2, N2 and CH4 Adsorption into Novel MOF/Graphene-like Composites

In this work we measured, with a pressure decay technique, the adsorption in static conditions of different gases (N₂, CH₄, CO₂) in novel types of metal organic frameworks (MOFs) selective to CO₂, modified with different strategies, for CO₂ capture processes in post and precombustion as well as natural gas upgrading.

The starting MOF material is HKUST-1 or Cu₃(BTC)₂, which shows high adsorption and selectivity for CO₂. Starting from this structure, we evaluated the effect of intercalation, in the assembling stage, of carbonaceous graphene-like layers (GL) that induce modifications to the structure and porosity distribution, generating the so-called hybrid MOF-GL materials (MGLs).[1] We also investigated the effect of the partial replacement of Copper centers with Zinc centers (ZnMOFs), and of the simultaneous presence of Zinc centers and of graphene like layers (ZnMGLs). The different materials show rather different gas adsoprtion properties, that depend on the chemical structure and on the material porosity. In particular, the samples with the highest adsorption capacity in comparison to HKUST-1 are the MGL ones, while the samples ZnMOF and ZnMGL have a lower CO₂ uptake. The majority of adsorption isotherms shows a type I behaviour.

References

[1] M. Alfè, V. Gargiulo, L. Lisi, R. Di Capua, Synthesis and characterization of conductive copper metal-organic framework/graphene-like composites, Materials Chemistry and Physics 147 (2014) 744-750