Programming MOFs for water sorption: amino-functionalized MIL-125 and UiO-66 for heat transformation and heat storage applicationsElectronic supplementary information (ESI) available: Synthesis and instrument details, PXRD patterns, N2 sorption isotherms, H2O sorption isotherms at T = 40 °C. See DOI: 10.1039/c3dt51471d

• Main Authors: Jeremias, Felix, Lozan, Vasile, Henninger, Stefan K, Janiak, Christoph
• Format: Journal Article
• Language: English
• Published: 29.10.2013
• DOI: 10.1039/c3dt51471d
• ISSN: 1477-9226

Sorption-based heat transformation and storage appliances are very promising for utilizing solar heat and waste heat in cooling or heating applications. The economic and ecological efficiency of sorption-based heat transformation depends on the availability of suitable hydrophilic and hydrothermally stable sorption materials. We investigated the feasibility of using the metal-organic frameworks UiO-66(Zr), UiO-67(Zr), H 2 N-UiO-66(Zr) and H 2 N-MIL-125(Ti) as sorption materials in heat transformations by means of volumetric water adsorption measurements, determination of the heat of adsorption and a 40-cycle ad/desorption stress test. The amino-modified compounds H 2 N-UiO-66 and H 2 N-MIL-125 feature high heat of adsorption (89.5 and 56.0 kJ mol −1 , respectively) and a very promising H 2 O adsorption isotherm due to their enhanced hydrophilicity. For H 2 N-MIL-125 the very steep rise of the H 2 O adsorption isotherm in the 0.1 < p / p 0 < 0.2 region is especially beneficial for the intended heat pump application. Reversible water adsorption/desorption renders hydrophilic Ti- and Zr-MOFs interesting candidates for sorption-based chilling or heat pump systems.