A low-temperature ammonia synthesis process is required for on-site synthesis. Barium-doped calcium amide (Ba-Ca(NH ) ) enhances the efficacy of ammonia synthesis mediated by Ru and Co by 2 orders of magnitude more than that of a conventional Ru catalyst at temperatures below 300 °C. Furthermore, the presented catalysts are superior to the wüstite-based Fe catalyst, which is known as a highly active industrial catalyst at low temperatures and pressures. Nanosized Ru-Ba core-shell structures are self-organized on the Ba-Ca(NH ) support during H pretreatment, and the support material is simultaneously converted into a mesoporous structure with a high surface area (>100 m g ). These self-organized nanostructures account for the high catalytic performance in low-temperature ammonia synthesis.
Efficient and stable catalysts for ammonia synthesis under mild conditions are required to meet the strong demand for NH 3 as an important precursor chemical and hydrogen carrier. Here we report that during ammonia synthesis, flat-shaped Ru nanoparticles with a narrow distribution (2.1 ± 1.0 nm) and self-organized on Ca(NH 2 ) 2 exhibit high catalytic performance far exceeding alkalipromoted Ru-based catalysts in yield and turnover frequency (TOF). This catalyst enables continuous NH 3 production, even at 473 K under ambient pressure. During ammonia synthesis, Ru nanoparticles are distinctly anchored on the surface of Ca(NH 2 ) 2 by strong Ru−N interaction, which leads to the epitaxial growth of Ru on the support surface. The high catalytic performance is due to the formation of high-density flat-shaped Ru nanoparticles and high electron donor ability at the Ru/ Ca(NH 2 ) 2 interface. The catalytic stability is significantly improved by Ba-doping of Ca(NH 2 ) 2 , and no degradation was observed after ca. 700 h of operation.
We report the synthesis of Co-Mo alloy nanoparticles with a uniform distribution of the alloy elements on CeOvia sodium naphthalenide-driven reduction. The resulting sample functions as a highly efficient and stable catalyst for ammonia synthesis. Based on the metal weight, the catalytic activity is ca. 20 times higher than that of CoMoN.
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