Ammonia Production via a Two-Step Al₂O₃/AlN Thermochemical Cycle. 2. Kinetic Analysis

The production of ammonia via a two-step cyclic process is considered, consisting of an endothermic carboreduction of Al₂O₃ in a N₂ atmosphere to form AlN, followed by exothermic steam-hydrolysis of AlN to produce NH₃ and to reform Al₂O₃. The chemical kinetics of both steps were experimentally investigated by thermogravimetry and gas chromatography, without added catalysts and under external supply of process heat. Rate laws and the corresponding Arrhenius kinetic parameters were determined by applying the unreacted core model for the AlN production and the shrinking core model for the AlN hydrolysis.