Improving resource efficiency and reducing carbon emissions through low-temperature, low-pressure ammonia synthesis

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Ammonia is the second most commonly produced industrial chemical worldwide, reaching an estimated global production of 176 megatonnes/year (2022). Approximately 80% of ammonia is used for fertiliser production, playing a critical role in increasing agricultural output and supporting the growing global population. Indeed, it is estimated that ammonia in fertiliser now supports approximately half of the global population.Ammonia synthesis currently relies on the 110-year old Haber-Bosch process, which reacts nitrogen and hydrogen over fused-iron catalysts under high-temperature (?400 degC), high-pressure (?200 bar) conditions.This process faces two key resource efficiency issues:(i) Materials: Operating reactors under high-temperature, high-pressure conditions requires significant materials investment and high CAPEX costs. Notably, a large-scale 850,000 tonne/year ammonia plant requires an estimated 225 tonnes of stainless steel for the synthesis reactors and costs an estimated £0.8BN in CAPEX.(ii) Minerals: The Haber-Bosch process relies on a fused-iron catalyst, which is typically prepared by melting natural magnetite from Sweden with various promoters, cooling the melt, and mechanically granulating the melt into small particles, which are then screened to obtain the target particle size. A large-scale 850,000 tonne/year ammonia plant requires an estimated 74,520 kg of fused-iron catalyst, with a lifetime of approximately 10 years. Since even pre-reduced, stabilised fused-iron catalysts require 30-40 hours for activation, the Haber-Bosch process is operated under "always-on" conditions, limiting production flexibility and precluding the use of intermittent renewable energy as a power source.Underpinning the resource efficiency challenges associated with the Haber-Bosch process are the high energy requirements and carbon emissions. The Haber-Bosch process consumes approximately 2% of the global energy budget (8.6 EJ/year) and contributes around 1.8% of global carbon dioxide emissions (500 megatonnes/year). With demand for ammonia projected to rise nearly 40% by 2050, largely driven by fertiliser requirements, business-as-usual ammonia production is incompatible with global net-zero targets.Innovate UK funding through Resource Efficiency for Materials and Manufacturing call brings together a world-class consortium spanning industry and academia to improve resource efficiency and reduce carbon emissions through developing a low-temperature, low-pressure ammonia synthesis process.