Impact of microchannel geometry on ammonia decomposition utilizing ruthenium-based catalysts: a numerical assessment

Abstract The decomposition of ammonia (NH 3 ) presents a viable pathway for hydrogen production, leveraging ammonia’s high hydrogen content and established infrastructure. This study numerically assesses the impact of microchannel reactor geometry on the efficiency of NH 3 decomposition, employing ruthenium-based catalysts. A computational fluid dynamics (CFD) model was developed and validated against experimental data, incorporating the Temkin-Pyzhev kinetic model. The analysis explores various microchannel geometries with different catalyst distribution strategies, including rectangular and semicircular configurations. Results indicate that optimizing channel geometry significantly enhances hydrogen production efficiency while reducing catalyst consumption. The 1.5X (scaled with respect to the base case) thicker configuration achieved a 10 % improvement in conversion per catalyst mass compared to the base case. In contrast, constant catalyst thickness in a 2X-expanded channel demonstrated the lowest conversion efficiency. Additionally, semicircular geometries exhibited lower pressure drops, offering advantages for scaling up hydrogen production. These findings contribute to the design of advanced microreactors for sustainable hydrogen production, highlighting the importance of geometric optimization in enhancing catalytic performance and process efficiency.