Thermal decompositions and heat capacities study of a co-based zeolitic imidazolate framework
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Thermal decompositions and heat capacities study of a co‑based zeolitic imidazolate framework Yumei Luo1,2 · Weiwei Cui1 · Yongjin Zou1 · Hailiang Chu1 · Fen Xu1 · Lixian Sun1,2 Received: 3 September 2019 / Accepted: 1 January 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract Zeolitic imidazolate frameworks (ZIFs), a sub-class of metal–organic frameworks, have also been intensively investigated in many fields because of the excellent thermal stability. However, the thermal decomposition and heat capacity of ZIFs were little studied. ZIF-67 was very classical which has been widely used for C O2 capture and gas separation, and its derivatives were widely applied in energy storage and conversion. Herein, the thermal decomposition process of ZIF-67 and its intermediates were studied. Moreover, the molar heat capacity and the thermodynamic functions of ZIF-67 were explored for the first time. The molar heat capacity increased as the temperature increased in the temperature range of 296–352 K. Keywords Molar heat capacity · Thermal decomposition · Metal–organic frameworks · Thermodynamic functions
Introduction Metal–organic frameworks are self-assembled by the metal ions or metal clusters and organic linkers via coordination bonds [1]. MOFs as a new type of materials show high specific surface areas, tunable porosities, and various topologies. Considerable research efforts have been devoted to MOFs which apply in many fields such as hydrogen storage, CO2 capture, gas separation, electrochemical energy storage, and conversion [2–5]. Much work pays more attention to the capacity, temperature, and pressure of capturing gas molecules into MOFs, while a relatively few researches focus on the thermodynamic properties of MOFs, which are also beneficial to fully understand thermal effects among different molecules and MOFs during the adsorption processes.
* Fen Xu [email protected] * Lixian Sun [email protected] 1
Guangxi Key Laboratory of Information Materials, Guangxi Collaborative Innovation Center of Structure and Property for New Energy and Materials, School of Material Science and Engineering, Guilin University of Electronic Technology, Guilin 541004, People’s Republic of China
School of Electronic Engineering and Automation, Guilin University of Electronic Technology, Guilin 541000, People’s Republic of China
2
Molar heat capacities at different temperatures are basic data of thermodynamic properties, and they are crucial not only for characterizing the adsorbent material itself but also for optimizing the adsorption process. Larger heat capacity of a solid adsorbent could reduce the undesired thermal effects arising from the heat of adsorption [6–8]. In recent years, heat capacities of MOFs were studied by more and more researchers [9–11]. For example, Rosen et al. presented the molar heat capacities from 1.8 to 300 K of zinc 2-methylimidazolate recently [12]. Liu et al. obtained the molar heat capacities of one–three-dimensional MOF (CAU-1) in the temperature range 298–1023 K for the first time [1
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