(569eu) Kinetic Modelling of Sr3N2 Nitridation for Chemical Looping Ammonia Synthesis

Chemical Looping Ammonia Synthesis (CLAS) has been developed as a promising ammonia production route, offering minimal reliance on fossil fuels, enhanced process conditions, flexibility and potential for renewable energy integration. CLAS typically operates by decomposing the overall ammonia synthesis reaction into two or more sub-reactions, which are carried out using a mediating Nitrogen carrier. For instance, strontium nitride (Sr₃N₂) is a strong candidate for CLAS due to its suitable thermodynamic properties. However, the intrinsic kinetics of Sr₃N₂ nitridation, a crucial step in the CLAS process, are not well understood. This work contributes to the field by offering a detailed kinetic analysis of the nitridation of Strontium nitride (Sr₃N₂), highlighting the importance of operational conditions in optimizing the reaction for CLAS. This work focuses on applying different solid-state reaction models to the nitridation of Sr₃N₂ in order to describe the reaction mechanism and estimate the kinetic parameters that govern the nitridation process. The developed kinetic model serves as a valuable tool for predicting the performance of the nitridation process, facilitating the design and optimization of chemical looping operations for efficient and sustainable ammonia production. Nitridation of Sr₃N₂ was done both isothermally and non-isothermally under controlled conditions using Thermogravimetric analysis (TGA). For the Isothermal analysis, the experiment was carried out by heating the equipment up to the reaction temperature in argon flow (20ml/min) and reacting isothermally with Nitrogen (20ml/min) at 4 different temperatures from 275^oC – 350^oC. Similarly, Non-Isothermal analysis was done by simultaneously heating and flowing Nitrogen over the at 4 different heating rates from 5K/min to 20K/min. Experimental data obtained from both methods was fitted to different solid-state reaction models to discriminate the mechanism predominant in the solid-state reaction and estimate the required kinetic parameters for each model.