Specific heat capacities of MOF-5, Cu-BTC, Fe-BTC, MOF-177 and MIL-53 (Al) over wide temperature ranges: Measurements and application of empirical group contribution method

摘要

Specific heat capacities of five MOFs: MOF-5, Cu-BTC, Fe-BTC, MIL-53 (Al) and MOF-177 are reported over wide temperature ranges. For MOF-5, which is the primary candidate material down selected by the Hydrogen Storage Engineering Center of Excellence (HSECoE) for cyro-adsorptive vehicular hydrogen storage, specific heat capacity in the range 2-300 K is obtained by combining the measurements using a Calvet calorimeter and a direct adiabatic relaxation calorimeter while for remaining MOFs, C(p)s are measured in the temperature range 80-320 K using the Calvet calorimeter alone. All MOFs exhibit monotonically increasing specific heat capacities with no visible thermal anomalies implying the absence of any temperature-induced phase transitions in the temperature range considered. A simple ion-based group contribution approach is applied to empirically predict the specific heat capacities of all MOFs at 323 K. (C) 2015 Elsevier Inc. All rights reserved.