Department of Science Education, Graduate School of Education, Hiroshima University, 1-1-1 Kagamiyama, Higashi-Hiroshima, 739-8524, Japan.
Phys Chem Chem Phys. 2018 May 9;20(18):12557-12573. doi: 10.1039/c8cp01138a.
This article demonstrates a kinetic approach to partially overlapping multistep chemical reactions in solid-gas systems as exemplified by the thermal decomposition of granular sodium perborate tetrahydrate. This reaction proceeds via successive thermal dehydration and decomposition occurring at different temperatures to form sodium metaborate. Each reaction process comprises several kinetic steps originating from different physicochemical and physico-geometric phenomena. The partially overlapping multistep processes were characterized using available thermoanalytical techniques and microscopic observations. Conventional isoconversional kinetic analysis and empirical mathematical deconvolution were applied to each reaction process as preliminary kinetic approaches to extracting provable kinetic information. Then, each reaction process was analyzed kinetically based on a cumulative kinetic equation, i.e., kinetic deconvolution analysis. The results of the kinetic deconvolution analysis were further examined by comparison with other kinetic information for the specific kinetic steps obtained from different thermoanalytical measurements. From the results of this comprehensive kinetic approach, the kinetic features of the thermal dehydration and decomposition processes were revealed by identifying their contributing physicochemical and physico-geometric phenomena and evaluating their influences on the overall multistep processes.
本文展示了一种针对固-气多步化学反应中部分重叠的动力学方法，以颗粒状过硼酸钠四水合物的热分解为例。该反应通过连续的热脱水和在不同温度下发生的分解进行，生成偏硼酸钠。每个反应过程都由几个源自不同物理化学和物理几何现象的动力学步骤组成。使用可用的热分析技术和微观观察对部分重叠的多步过程进行了表征。常规的等转化率动力学分析和经验数学反卷积被应用于每个反应过程，作为提取可靠动力学信息的初步动力学方法。然后，基于累积动力学方程（即动力学反卷积分析）对每个反应过程进行了动力学分析。通过与从不同热分析测量获得的特定动力学步骤的其他动力学信息进行比较，进一步检查了动力学反卷积分析的结果。通过识别热脱水和分解过程的贡献物理化学和物理几何现象，并评估它们对整个多步过程的影响，从这种综合动力学方法的结果中揭示了热脱水和分解过程的动力学特征。
