Inherently safer design for synthesis of 3-methylpyridine-N-oxide

Alkyl pyridine-N-oxide can decompose to pyridine which readily leads to explosion accident in air. Therefore, risk analysis and inherently safer design are necessary for this process. This article aims to study the thermal hazards of the process of 3-methylpyridine oxidized by hydrogen peroxide, and then the corresponding Inherently Safer Designs (ISDs) were proposed. The inherent hazards during the process were first qualitatively evaluated by Qualitative Assessment for Inherently Safer Design. Then, the reaction calorimeter was employed to analyze the thermal hazards of the target reaction. Meanwhile, the Integrated Inherent Safety Index methods were simplified to quantitatively estimate the level of inherent safety of the process. The results show that the potential risk of the process is 87.2% which is at the high risk level. Based on the hazard identification and assessment results, three ISDs, namely adding catalyst (ISD I), improving reaction condition (ISD II), and using a tubular (ISD III), were proposed to enhance the safety. Finally, combining comparative experiments with ISI methods, an effect evaluation model for ISD was established to verify the rationality of the ISDs. The results indicate that the reaction hazards are diminished when three ISDs are utilized in production process. The inherent safety level of the reaction is increased by 22.2%, 50.7%, and 31.8%, respectively.