Effect of metal–ligand ratio on the CO2 adsorption properties of Cu–BTC metal–organic frameworks

Abstract

Initially, in the synthesis of Cu–BTC MOFs some fraction of Cu was expected to be replaced with Mg to enhance its CO₂ adsorption properties. Indeed, an enhancement in the specific surface area, microporosity and CO₂ adsorption capacity was observed; however, Mg was not detected. Therefore, additional syntheses of Cu–BTC MOFs with the same Cu to BTC ratios were performed but in the absence of Mg to explain the observed enhancement. It was found that the adjustment of the Cu–BTC ratio to 1.09 : 1.0, which differs from that reported in the literature, resulted in a Cu–BTC MOF with higher specific BET surface area, larger micropore volume, and consequently, superior CO₂ adsorption of 9.33 mmol g⁻¹ at 0 °C and 1 bar.