物理化学学报

所属专题: 热分析动力学和热动力学

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三维无溶剂含能Ag-MOF的制备、热分解动力学及爆炸性能

乔成芳1, 吕磊3, 许文风2, 夏正强2, 周春生1, 陈三平2, 高胜利1,2   

  1. 1 商洛学院化学工程与现代材料学院, 陕西省尾矿资源综合利用重点实验室, 陕西 商洛 726000;
    2 西北大学化学与材料科学学院, 教育部合成与天然功能分子化学重点实验室, 西安 710127;
    3 延安大学化学与化工学院, 陕西省化学反应工程重点实验室, 陕西 延安 716000
  • 收稿日期:2019-05-31 修回日期:2019-06-27 录用日期:2019-06-27 发布日期:2019-07-01
  • 通讯作者: 陈三平 E-mail:sanpingchen@126.com
  • 基金资助:
    国家自然科学基金(21727805,21673180,21703135,21803042),陕西省自然科学基础研究计划(2017JZ002,2018JM5180,2019JQ-249,2019JQ-067),陕西省化学反应工程重点实验室项目(14JS112)和第64批中国博士后科学基金面上项目(2018M643706)资助项目

Synthesis, Thermal Decomposition Kinetics and Detonation Performance of a Three-Dimensional Solvent-Free Energetic Ag(I)-MOF

QIAO Chengfang1, LÜ Lei3, XU Wenfeng2, XIA Zhengqiang2, ZHOU Chunsheng1, CHEN Sanping2, GAO Shengli1,2   

  1. 1 Shaanxi Key Laboratory of Comprehensive Utilization of Tailings Resources, College of Chemical Engineering and Modern Materials, Shangluo University, Shangluo 726000, Shaanxi Province, P. R. China;
    2 Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, P. R. China;
    3 Department of Chemistry and Chemical Engineering, Shaanxi Key Laboratory of Chemical Reaction Engineering, Yan'an University, Yan'an 716000, Shaanxi Province, P. R. China
  • Received:2019-05-31 Revised:2019-06-27 Accepted:2019-06-27 Published:2019-07-01
  • Contact: CHEN Sanping E-mail:sanpingchen@126.com
  • Supported by:
    The project was supported by the National Natural Science Foundation of China (21727805, 21673180, 21703135, 21803042), Natural Science Basic Research Program of Shaanxi (2017JZ002, 2018JM5180, 2019JQ-249, 2019JQ-067), the Project of Shaanxi Key Laboratory of Chemical Reaction Engineering (14JS112) and the 64th China Postdoctoral Science Foundation Funded Project (2018M643706).

摘要: 溶剂分子的存在会严重降低能量金属-有机框架(EMOFs)材料的爆热和稳定性,开发无溶剂的EMOFs已成为制备高能量密度材料的有效策略。本文将高能的2,3-二(5-1H-四唑基)吡嗪(H2DTPZ)配体与银离子作用在水热条件下制备了一例无溶剂的EMOF[Ag2(DTPZ)]n1)(含氮量:32.58%),并借助元素分析、红外光谱、X射线衍射以及热分析等技术对其组成和结构进行了表征。化合物1中,DTPZ2-配体构型高度扭转并以八齿配位模式桥联Ag+离子形成三维框架结构(ρ=2.812 g·cm-3),配体大的位阻效应和强的配位能力有效阻止了溶剂分子与金属配位或占据框架空腔;同时,不同配体四唑环间强的π-π堆积作用(质心-质心距离为0.34461(1)nm),使得化合物1呈现高的热稳定性(Te=619.1 K,Tp=658.7 K)。热分析研究表明化合物1分解主要发生一步快速失重并伴有剧烈的放热,呈现出潜在的含能特质。通过差示扫描量热(DSC)技术对化合物1的热分解过程进行了非等温热动力学分析(基于Kissinger和Ozawa-Doyle方法)并获得了相应热动力学参数(活化能Ea=272.1 kJ·mol-1Eo=268.9 kJ·mol-1;lgA=19.67 s-1)。进一步基于升温速率趋于0时的分解峰温和外延起始温度,计算得到了相关热力学参数(活化焓ΔH=266.9 kJ·mol-1,活化熵ΔS=125.4 J·mol-1·K-1,活化自由能ΔG=188.3 kJ·mol-1)以及热爆炸临界温度(Tb=607.1 K)和自加速分解温度(TSADT=595.8 K),结果表明该化合物具有良好的热安全性,其分解属非自发的熵驱动过程。借助精密转动弹热量计测定了化合物1的恒容燃烧能(Qv)并计算得其标准摩尔生成焓为(2165.99 ±0.81)kJ·mol-1。爆轰和安全性能测试表明,化合物1对撞击和摩擦均不敏感,爆热值达10.15 kJ·g-1,远高于常见硝铵类炸药奥克托金(HMX)、黑索金(RDX)和2,4,6-三硝基甲苯(TNT),是一例有前景的高能钝感含能材料。

关键词: 含能金属-有机框架, 热分解动力学, 热稳定性, 爆炸性能, 感度

Abstract: Solvent molecules can significantly reduce the heat of detonation and stability of energetic metal-organic framework (EMOF) materials, and the development of solvent-free EMOFs has become an effective strategy to prepare high-energy density materials. In this study, a solvent-free EMOF,[Ag2(DTPZ)]n (1) (N%=32.58%), was synthesized by reacting a high-energy ligand, 2,3-di(1H-tetrazol-5-yl)pyrazine (H2DTPZ), with silver ions under hydrothermal conditions, and it was structurally characterized by elemental analysis, infrared spectroscopy, X-ray diffraction, and thermal analysis. In 1, the DTPZ2- ligands that adopted a highly torsional configuration bridged the Ag+ ions in an octadentate coordination mode to form a three-dimensional framework (ρ=2.812 g·cm-3). The large steric effect and strong coordination ability of DTPZ2- effectively prevented the solvent molecules from binding with the metal centers or occupying the voids of 1. Moreover, the strong π-π stacking interactions[centroid-centroid distance=0.34461(1) nm] between the tetrazole rings in different DTPZ2- ligands provided a high thermal stability to the framework (Te=619.1 K, Tp=658.7 K). Thermal analysis showed that a one-step rapid weight loss with intense heat release primarily occurred during the decomposition of 1, suggesting potential energetic characteristics. Non-isothermal thermokinetic analyses (based on the Kissinger and Ozawa-Doyle methods) were performed using differential scanning calorimetry to obtain the thermoanalysis kinetic parameters of the thermodecomposition of 1 (Ea=272.1 kJ·mol-1, Eo=268.9 kJ·mol-1; lgA=19.67 s-1). The related thermodynamic parameters[enthalpy of activation (ΔH=266.9 kJ·mol-1), entropy of activation (ΔS=125.4 J·mol-1·K-1), free energy of activation (ΔG=188.3 kJ·mol-1)], critical temperature of thermal explosion (Tb=607.1 K), and self-accelerating decomposition temperature (TSADT=595.8 K) of the decomposition reaction were also calculated based on the decomposition peak temperature and extrapolated onset temperature when the heating rate approached zero. The results revealed that 1 featured good thermal safety, and its decomposition was a non-spontaneous entropy-driven process. The standard molar enthalpy for the formation of 1 was calculated to be (2165.99 ±0.81) kJ·mol-1 based on its constant volume combustion energy determined using a precise rotating oxygen bomb calorimeter. Detonation and safety performance tests revealed that 1 was insensitive to impact and friction, and its heat of detonation (10.15 kJ·g-1) was higher than that of common ammonium nitrate explosives, such as octogen (HMX), hexogene (RDX), and 2,4,6-trinitrotoluene (TNT), indicating that 1 is a promising high-energy and insensitive material.

Key words: Energetic metal-organic framework, Thermal decomposition kinetics, Thermal stability, Detonation performance, Sensitivity

MSC2000: 

  • O642