Electrification of Catalytic Ammonia Production and Decomposition Reactions: From Resistance, Induction, and Dielectric Reactor Heating to Electrolysis

Abstract

The conventional method for synthesizing ammonia is a power-hungry process that requires high operating temperatures (400–500 °C) in addition to elevated pressures (150–300 bar). The reaction is normally catalyzed by magnetite-based particles, and occurs between a single mole of nitrogen and three moles of hydrogen to form two moles of ammonia. The original Haber–Bosch process was developed and patented in 1916 by Fritz Haber and Carl Bosch. Since then, it has been extensively upgraded and optimized, with many improvements in the area of catalysis. Iron- and ruthenium-based catalysts are commonly used, where the active metal is deposited onto an appropriate support material. However, this method remains rather costly for the mass production of ammonia. The pursuit of a high-efficiency production process combined with the desirable use of renewables has driven the development of alternative, stand-alone methods (such as electrolysis, plasma- and microwave-mediated synthesis, various photochemical pathways, and catalysis aided by magnetic heating) as well as completely separate reactant-production procedures coupled with the traditional Haber–Bosch reactors. This review aims to highlight and critically evaluate recent developments in the electrification of ammonia production and decomposition.