Muravyev Nikita V, Koga Nobuyoshi, Meerov Dmitry B, Pivkina Alla N
Semenov Institute of Chemical Physics, Russian Academy of Sciences, 4 Kosygin Str., 119991, Moscow, Russia.
Chemistry Laboratory, Department of Science Education, Graduate School of Education, Hiroshima University, 1-1-1 Kagamiyama, Higashi-Hiroshima, 739-8524, Japan.
Phys Chem Chem Phys. 2017 Jan 25;19(4):3254-3264. doi: 10.1039/c6cp08218a.
This study focused on kinetic modeling of a specific type of multistep heterogeneous reaction comprising exothermic and endothermic reaction steps, as exemplified by the practical kinetic analysis of the experimental kinetic curves for the thermal decomposition of molten ammonium dinitramide (ADN). It is known that the thermal decomposition of ADN occurs as a consecutive two step mass-loss process comprising the decomposition of ADN and subsequent evaporation/decomposition of in situ generated ammonium nitrate. These reaction steps provide exothermic and endothermic contributions, respectively, to the overall thermal effect. The overall reaction process was deconvoluted into two reaction steps using simultaneously recorded thermogravimetry and differential scanning calorimetry (TG-DSC) curves by considering the different physical meanings of the kinetic data derived from TG and DSC by P value analysis. The kinetic data thus separated into exothermic and endothermic reaction steps were kinetically characterized using kinetic computation methods including isoconversional method, combined kinetic analysis, and master plot method. The overall kinetic behavior was reproduced as the sum of the kinetic equations for each reaction step considering the contributions to the rate data derived from TG and DSC. During reproduction of the kinetic behavior, the kinetic parameters and contributions of each reaction step were optimized using kinetic deconvolution analysis. As a result, the thermal decomposition of ADN was successfully modeled as partially overlapping exothermic and endothermic reaction steps. The logic of the kinetic modeling was critically examined, and the practical usefulness of phenomenological modeling for the thermal decomposition of ADN was illustrated to demonstrate the validity of the methodology and its applicability to similar complex reaction processes.
本研究聚焦于一种特定类型的多步非均相反应的动力学建模，该反应包含放热和吸热反应步骤，以熔融二硝酰胺铵（ADN）热分解实验动力学曲线的实际动力学分析为例。众所周知，ADN的热分解是一个连续的两步质量损失过程，包括ADN的分解以及原位生成的硝酸铵的后续蒸发/分解。这些反应步骤分别对整体热效应提供放热和吸热贡献。通过P值分析考虑从热重分析（TG）和差示扫描量热法（DSC）获得的动力学数据的不同物理意义，利用同时记录的TG-DSC曲线将整个反应过程解卷积为两个反应步骤。使用包括等转化率法、联合动力学分析和主曲线法在内的动力学计算方法对如此分离为放热和吸热反应步骤的动力学数据进行动力学表征。考虑到对源自TG和DSC的速率数据的贡献，将每个反应步骤的动力学方程之和再现整体动力学行为。在再现动力学行为期间，使用动力学反褶积分析优化每个反应步骤的动力学参数和贡献。结果，ADN的热分解成功地建模为部分重叠的放热和吸热反应步骤。对动力学建模的逻辑进行了严格审查，并说明了现象学建模对ADN热分解的实际实用性，以证明该方法的有效性及其对类似复杂反应过程的适用性。
