Zhen Cheng,Lei Ni,Junjie Wang,Juncheng Jiang,Hang Yao,Qiang Chen,Fusheng Cui,Wei Jiang,Shuliang Ye
The synthesis of Grignard reagents, which are formed by the reaction of magnesium and organic halides (RX), is hazardous because of the highly exothermic nature of this reaction. In this work, calorimetry and infrared (IR) spectroscopy were used to identify the exothermic mechanism and process hazards for the synthesis of n -butylmagnesium bromide Grignard reagent ( n -BuMgBr) in diethyl ether (DE), tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-MeTHF), cyclopentylmethyl ether (CPME), and diethylene glycol butyl ether (DGBE). The latter three solvents were chosen by the substitution principle of the “inherent safety” design concept, which aims to reduce the risk of the target reaction in a fundamental manner. An EasyMax102 calorimeter was used to characterize the exothermic behavior of the reactions using isothermal and isoperibolic experiments carried out in a semi-batch glass reactor coupled with an IR probe to monitor changes in the species and concentrations during the reaction process. An adiabatic TAC-500A calorimeter was also used to understand the adiabatic decomposition behavior of the products obtained in the isothermal experiments under the worst-case (cooling failure and thermal runaway) scenario. Meanwhile, density functional theory calculations were performed to understand the reaction pathway and associated energies based on the experimental data. Further, the risk assessment of thermal runaway was analyzed using a risk matrix and a Stoessel criticality diagram. The results indicate that the risk of the reactions when using 2-MeTHF, CPME, and DGBE are all class 1, making reactions in these solvents inherently safer than those using DE or THF, which were both class-3 risks. These findings provide further evidence that 2-MeTHF, CPME, and DGBE are safer than the typical solvents used for the industrial production of Grignard reagents.
Metastable intermixed composites (MICs) have received increasing attention in the field of energy materials in recent years due to their high energy and good combustion performance. The exploration of ways of improving their potential release of heat is still underway. In this study, Al–CuO/graphene oxide (GO) nanocomposites were prepared using a combination of the self-assembly and in-suit synthesis methods. The formulation and experimental conditions were also optimized to maximize the exothermic heat. The DSC analysis shows that the addition of the GO made a significant contribution to the exothermic effect of the nanothermite. Compared with the Al–CuO nanothermite, the exothermic heat of the Al–CuO/GO nanocomposites increase by 306.9–1166.3 J/g and the peak temperatures dropped by 7.9–26.4 °C with different GO content. The reaction mechanism of the nanocomposite was investigated using a DSC and thermal reaction kinetics analysis. It was found that, compared with typical thermite reactions, the addition of the GO changed the reaction pathway of the nanothermite. The reaction products included CuAlO2. Moreover, the combustion properties of nanocomposite were investigated. This work reveals the unique mechanism of GO in thermite reactions, which may promote the application of carbon materials in nanothermite.Keywords:graphene oxide;metastable intermixed composites (MICs);nanothermite;thermokinetics;combustion
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