image: (a) Conversion of nuclear energy into chemical energy remains to be developed. (b) γ-Ray radiation-induced ammonia synthesis from nitrogen and water. HVL: half-value layer.
Credit: ©Science China Press
This study is led by Dr. Zhibo Liu (Peking University).
Nitrogen (N) is an essential element for life activities. N2, the most abundant and readily available nitrogen source in nature, accounts for up to 78% of the air. However, due to the high energy of the N≡N triple bond (941 kJ·mol−1), N2 is difficult to be activated. Haber−Bosch ammonia production is considered one of the most significant chemical transformations ever developed, promoting the rapid development of global agriculture and feeding half of the world's population. Yet, this process is carried out at a high temperature of ∼500 °C and a pressure of ≤20 MPa, accompanied by a large amount of carbon dioxide emissions. Therefore, developing efficient ammonia synthetic technology has received widespread attention.
Nuclear energy represents a low-carbon and efficient source of power. However, the large amount of ionizing radiation (such as γ-rays) generated from nuclear reactors has not been well developed and utilized. This team discovered that hydrated electrons (e−aq) generated from water radiolysis can drive the NH3 synthesis from N2 and water. The Ru/SiO2 catalyst synthesized by γ-ray radiation could substantially improve NH3 production. By optimizing reaction conditions such as the type of catalysts, the usage of catalysts, reaction time, reaction pressure, and additives, the conversion efficiency would be further improved, and the energy conversion efficiency was as high as 563.7 mgNH3·MJ−1. At a total absorbed dose of 312.0 kGy, the NH3 concentration could reach 5.1 mM. Cycle tests showed that the radiation-synthesized Ru/SiO2 catalyst still maintained its catalytic activity in a radioactive environment, exhibiting good radiation stability.
This study develops an ionizing radiation-induced nitrogen fixation strategy, offering promising opportunities for converting nuclear energy into chemical energy and industrial applications of nuclear energy.
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See the article:
Radiocatalytic ammonia synthesis from nitrogen and water
https://doi.org/10.1093/nsr/nwae302
Journal
National Science Review