CO2 capture under humid conditions in NH2-MIL-53(Al): the influence of the amine functional group

Abstract

The hydrostable MIL-53(Al) and NH₂-MIL-53(Al) CO₂ capture properties were confirmed by kinetic uptake experiments, under different humidity conditions with maximum CO₂ captures of approximately 6.0 wt% and 4.6 wt%, respectively, at 5% RH at 30 °C. In the case of MIL-53(Al) this corresponds to a 1.7-fold increase (CO₂ capture) in comparison to anhydrous conditions. NH₂-MIL-53(Al) exhibited a considerably stronger affinity to water than MIL-53(Al), and its ability to capture CO₂, under humid conditions, was significantly reduced. The in situ FTIR experiments show how the hydrophobicity of the pores within MIL-53(Al) enhanced and sustained the CO₂ adsorption capabilities of the material under more realistic CO₂ capture conditions.