A New Member of the Metal-Porphyrin Frameworks Family: Structure, Physicochemical Properties, Hydrogen and Carbon Dioxide Adsorption

Abstract

A novel holmium-based porous metal-porphyrin framework, {(H₃ O⁺ )[Ho(H₂ TPPS)]^- ⋅ 4H₂ O}_n (denoted as UPJS-17), was synthesised by hydrothermal reaction. Structural analysis reveals, that UPJS-17 has a three-dimensional open framework. The framework is negatively charged and the negative charge is compensated by hydronium cation. The compound showed no N₂ adsorption but the Ar, CO₂ and H₂ . From the argon adsorption, the surface area of ~150 m² g^-1 was determined. Carbon dioxide adsorption was measured at various temperatures (0, 10, 20, 30 and 40 °C) and the compound showed the highest adsorption capacity (at 0 °C) of 7.0 wt % of CO₂ . From the carbon dioxide adsorption isotherms the isosteric heat of 56,5 kJ mol^-1 was determined. Hydrogen adsorption was studied at -196 °C with hydrogen uptake of 2.1 wt % at 1 bar.

Keywords: carbon dioxide adsorption; hydrogen adsorption; isosteric heats; metal-organic frameworks; metal-porphyrin frameworks.