Kinetics and safeties of 2-Ethyl-1-hexanol nitration in a capillary-microreactor

The nitration reaction and purification process of 2-Ethyl-1-hexanol is highly hazardous and characterized by severe thermal instability. Therefore, appropriate safety and kinetics studies are needed to promote safe synthesis in chemical production. However, obtaining accurate kinetic data is challenging due to its fast, highly exothermic, and heterogeneous characteristics. In this study, we obtained reaction kinetic parameters of 2-Ethyl-1-hexanol in a capillary-microreactor at different sulfuric acid concentrations and temperatures and calculated the per-exponential factor and activation energy. The thermal stability of 2-Ethylhexyl nitrate in mixed acids was determined by differential scanning calorimetry. Computational Fluid Dynamics was used to simulated the temperature distribution inside the capillary-microreactor for a T-shaped structure based on the kinetic and thermal stability data. The results show that even small-scale reaction tubes produce hot spots in the reactor inlet region in an isothermal environment. Under adiabatic conditions, the temperature inside the capillary is close to the decomposition temperature of the acid mixture. Therefore, the thermal safety of nitration reactions, even in small-scale microreactor systems, cannot be ignored. The results of this study have important implications for the industrial process design and safety for highly-exothermic reactions.

Graphical abstract