Water and ethanol stabilities of the crystal structure of the Cu-based metal-organic framework (MOF) HKUST-1 have been investigated. Vapour (water and ethanol) sorption isotherms and cyclability were measured by a dynamic strategy. The ethanol sorption capacity of HKUST-1 at 303 K remained unchanged contrasting water sorption (which decreased along with the sorption experiment time). Considering the binding energy of each sorbate with the open Cu(ii) sites, obtained by the use of diffusion coefficients, we showed the superior crystal stability of the HKUST-1 framework towards ethanol. Finally, a small quantity of ethanol (pre-adsorbed) slightly enhanced CO capture without crystal structure degradation.

Synthesis of a new HKUST-1 composite based on single-walled carbon nanotubes (SWCNTs) was successfully achieved (SWCNT@HKUST-1). SWCNTs were used as templates to grow rod-like HKUST-1 crystals over the surface of the nanotubes. N 2 adsorption properties showed an increment on the surface area and pore volume for the SWCNT@HKUST-1 composite. Furthermore, the CO 2 capture increased, from 7.92 to 8.75 mmol g –1 at 196 K up to 100 kPa, for the SWCNT@HKUST-1 composite. This enhancement was directly associated with the increase of the surface area of the composite. Additionally, an increase in the CO 2 heat of adsorption was estimated, from 30 to 39.1 kJ mol –1 for the SWCNT@HKUST-1 composite. In situ Raman experiments corroborated the favored CO 2 adsorption for the composite and provided an insight into the augmented hydrophobicity of the SWCNT@HKUST-1. Ethanol adsorption isotherms corroborated an increase in the hydrophobicity of the material upon the incorporation of carbon nanotubes.

The water-stable material NOTT-401 was investigated for CO 2 capture under humid conditions. Water adsorption properties of NOTT-401 were studied, and their correlation with CO 2 sequestration at different relative humidities (RHs) showed that the CO 2 capture increased from 1.2 wt % (anhydrous conditions) to 3.9 wt % under 5% RH at 30 °C, representing a 3.2-fold improvement.

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