Advances in process intensification and reactor engineering for hydrogen production from ammonia decomposition

Ammonia has emerged as a promising hydrogen carrier, making ammonia decomposition a key technology for on-site hydrogen production. However, as catalyst development via conventional modification approaches reaches its performance ceiling, process and engineering innovations are urgently needed to improve energy efficiency and hydrogen purity. This review comprehensively highlights recent advances in two critical areas: (1) process intensification strategies, including microwave heating, photothermal coupling, thermoelectric synergy, and plasma assistance. Compared with conventional thermocatalysis, these approaches can lower the temperature required for achieving a complete ammonia decomposition by approximately 100 °C and enhance catalytic activity by a factor of 2∼5; (2) advanced reactor designs, such as micro-reactors, membrane reactors, and monolithic reactors, which enhance heat/mass transfer and product separation (H₂ purity >99.9%). By summarizing the benefits and challenges of each approach, this review aims to support the development of efficient ammonia-to-hydrogen technologies for industrial application.