Autocatalytic reaction mechanism of nitric acid and formic acid mixtures based on thermal and in situ Raman spectroscopic analyses
Autocatalytic reaction mechanism of nitric acid and formic acid mixtures based on thermal and in situ Raman spectroscopic analyses
复制标题
DOI：
10.1007/s10973-020-10311-y
复制
发表时间：
2020-10
影响因子：
4.4
通讯作者：
Mahoko Ando;Michiya Fujita;Y. Izato;A. Miyake
中科院分区：
文献类型：
--
作者：
Mahoko Ando;Michiya Fujita;Y. Izato;A. Miyake
用硝酸氧化有机化合物有可能在热中性诱导期后发生失控的危险反应和爆炸。本研究的目的是为了更好地了解氧化反应机理，以阐明放热反应发生的具体条件。本研究以甲酸与硝酸的氧化反应为研究对象，以甲酸与硝酸的混合物为研究对象。根据热分析的结果，使用自催化反应模型来公式化15%硝酸和10%甲酸水溶液中的总反应速率。表观活化能为75.2 kJ mol−1，指前因子为7.87 × 108s−1。反应速率随硝酸或甲酸浓度的增加而增加，强调在较低浓度下处理混合物对于热安全性是重要的。通过热分析和现场拉曼光谱分析，发现随着反应的进行，亚硝酸的浓度增加，硝酸和甲酸转变为NO2、N2O4、HCO（O）NO、HCO（O）NO2，从亚硝酸开始的反应机理和甲酸与硝酸的氧化是涉及亚硝酸引发的循环的自催化反应。
The oxidation of organic compounds with nitric acid has the potential to undergo a runaway hazardous reaction and explosion after the thermal–neutral induction period. The purpose of this study is to obtain a better understanding of the oxidation reaction mechanism to clarify the specific conditions under which the exothermic reaction occurs. In this study, the oxidation reactions of formic acid with nitric acid were investigated to represent a typical mixture of organic compound and nitric acid. From the results of thermal analysis, the overall reaction rate in a 15% nitric acid and 10% formic acid aqueous solution was formulated using an autocatalytic reaction model. The apparent activation energy was 75.2 kJ mol−1, and the pre-exponential factor was 7.87 × 108s−1. The reaction rate increased with either nitric or formic acid concentrations, emphasizing that it is important to treat the mixture at lower concentrations for thermal safety. As a result of the thermal and in situ Raman spectroscopic analyses, it was found that the concentration of nitrous acid increased with the progress of the reaction as nitric acid and formic acid changed into NO2, N2O4, HCO(O)NO, HCO(O)NO2, and so on. The reaction mechanism started from nitrous acid and the oxidation of formic acid with nitric acid is an autocatalytic reaction involving this nitrous acid-initiated cycle.