Using Online Calorimetry to Ensure Process Safety: Scaling Up Catalytic Epoxidation of Alkenes
Advancing the chemical engineering fundamentals
Chemical Reaction Engineering: Practical Applications (T2-2c)
Keywords: Catalyzed epoxidation, Process safety, On-line calorimetry, kinetics studies, Scale up
In this work, online calorimetry was used to study the safety constraints associated with scaling up a manganese catalyzed epoxidation of styrene using NaHCO3-H2O2 buffer solution in a semi-batch reaction calorimeter (RC1e). Based on sequential addition of reagents, the online calorimetric data indicate that the exothermic catalytic reaction exhibits a characteristic temperature spike accompanied by spontaneous O2 gas release due to H2O2 decomposition which is primarily triggered by the intrinsic interactions between the MnSO4 and the NaHCO3-H2O2 buffer solution. Hence, the rate of buffer addition has a significant impact on the process safety. This study highlights how an optimized low dosing rate effectively minimizes the temperature spike and gas generation, and prevents any potential thermal runaway or O2 explosion in the full scale plant. However, even under safe operation, the DMF: H2O ratio was found to limit the maximum achievable epoxide production capacity due to the onset of bi-phase formation. Hence, further process optimization based on various factors was carried out to achieve maximum production capacity, low material consumption, and minimal waste generation. For scale-up, such optimization work provides a set of safe and efficient standard operating parameters for large-scale production. In the final stage of our scale-up work, kinetic studies were conducted assuming a second-order reaction under optimized operating conditions. This modeling work provides a preliminary design criterion for safe reactor scale-up with high efficiency and good reaction yield.
Presented Tuesday 18, 16:00 to 16:20, in session Chemical Reaction Engineering: Practical Applications (T2-2c).
