Towards Green Ammonia Synthesis through Plasma‐Driven Nitrogen Oxidation and Catalytic Reduction

Abstract

Ammonia is an industrial large‐volume chemical, with its main application in fertilizer production. It also attracts increasing attention as a green‐energy vector. Over the past century, ammonia production has been dominated by the Haber–Bosch process, in which a mixture of nitrogen and hydrogen gas is converted to ammonia at high temperatures and pressures. Haber–Bosch processes with natural gas as the source of hydrogen are responsible for a significant share of the global CO2 emissions. Processes involving plasma are currently being investigated as an alternative for decentralized ammonia production powered by renewable energy sources. In this work, we present the PNOCRA process (plasma nitrogen oxidation and catalytic reduction to ammonia), combining plasma‐assisted nitrogen oxidation and lean NOx trap technology, adopted from diesel‐engine exhaust gas aftertreatment technology. PNOCRA achieves an energy requirement of 4.6 MJ mol−1 NH3, which is more than four times less than the state‐of‐the‐art plasma‐enabled ammonia synthesis from N2 and H2 with reasonable yield (>1 %).

1921–2021: A Century of Renewable Ammonia Synthesis

“…Such technologies can follow the load fluctuations of renewable electricity, and are more easily scaled down than an electrolysis-based Haber-Bosch plant. However, scientific challenges remain for these technologies [82][83][84], and the economics are not (yet) competitive with an electrolysis-based Haber-Bosch process [85][86][87].…”

Plasma‐water‐based nitrogen fixation: Status, mechanisms, and opportunities

“…This self‐powered electrocatalytic system had an ammonia production rate of 2.4 μg/h. Hollevoet et al [ 27 ] proposed a process for nonthermal plasma nitrogen oxidation and catalytic reduction to ammonia. This process allowed the decentralized production of ammonia from water, air, and renewable energy through nitrogen oxidation and subsequent catalytic reduction in a lean NO x trap.…”

A bioreactor and nutrient balancing approach for the conversion of solid organic fertilizers to liquid nitrate-rich fertilizers: Mineralization and nitrification performance complemented with economic aspects

“…Agriculture and food production take a major share in the consumption of global resources, with for instance about 90% of global freshwater (Huang et al, 2019) and > 80% of global ammonia produced through the Haber-Bosch process (Hollevoet et al, 2020). However, during the artificial nitrogen fixation from N₂ to ammonia (NH₃) via the Haber-Bosch process, greenhouse gas and NH₃ emissions, and PM2.5 (particulate matter with a diameter less than 2.5 μm) formation can aggravate the global climate change and the air pollution, and thus threaten human health (Griffis & Baker, 2020).…”