Ammonia as a Hydrogen Carrier: Advances in Storage, Catalytic Decomposition, Kinetics, and Techno‐Economic Analysis

A carbon‐free energy system might use ammonia as a hydrogen carrier owing to its high hydrogen concentration, good liquefaction, and worldwide production and transportation infrastructure. Catalytic ammonia breakdown provides a CO ₂ ‐free hydrogen‐generating method, but high temperatures, catalyst deactivation, and expense restrict its practicality. This study covers important aspects of ammonia decomposition catalysts, including Ru‐, Ni‐, and Co‐based systems supported by carbon, Al ₂ O ₃ , and perovskite oxides. To develop structure–activity connections and identify rate‐limiting stages under various operating regimes, thermodynamic, kinetic, and fundamental reaction processes are examined. Ru‐based catalysts, especially those supported on conductive carbons and tailored perovskites, are standards for low‐temperature activity, but their high cost and stability prevent large‐scale application. Combining Ni‐based catalysts with Al ₂ O ₃ or basic perovskite supports offers a good balance between activity, cost, and commercial practicality, making them the dominant non‐noble alternatives. Due to strong metal–support interactions and alternate reaction routes, Co‐based catalysts in perovskite formulations seem promising despite being inherently less active. Support chemistry, promoters, metal dispersion, and oxygen vacancies are discussed, along with low‐temperature operation and scale‐up problems and research prospects.