Efficient and Stable Ammonia Synthesis by Self-Organized Flat Ru Nanoparticles on Calcium Amide
Efficient and Stable Ammonia Synthesis by Self-Organized Flat Ru Nanoparticles on Calcium Amide
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DOI：
10.1021/acscatal.6b01940
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发表时间：
2016-11-01
期刊：
影响因子：
12.9
通讯作者：
Hosono, Hideo
中科院分区：
文献类型：
--
作者：
Inoue, Yasunori;Kitano, Masaaki;Hosono, Hideo
氨气作为一种重要的前体化学品和氢载体的需求旺盛，需要在温和条件下高效、稳定的氨合成催化剂。本文报道了在合成氨过程中，以Ca(NH2)(2)为载体自组装的窄分布(2.1+/-1.0 nm)的平坦型Ru纳米粒子，在产率和转化率(TOF)方面远远超过碱促进型Ru基催化剂。这种催化剂即使在473K常压下也能连续生产NH3。在合成氨过程中，Ru纳米粒子通过强烈的Ru-N相互作用明显地固定在Ca(NH2)(2)表面，导致Ru在载体表面外延生长。高的催化性能是由于在Ru/Ca(NH2)(2)界面上形成了高密度的扁平形状的Ru纳米颗粒和高的电子给体能力。Ca(NH2)(2)掺杂显著提高了催化剂的稳定性，700h左右无降解现象。
Efficient and stable catalysts for ammonia synthesis under mild conditions are required to meet the strong demand for NH3 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(NH2)(2) exhibit high catalytic performance far exceeding alkali promoted Ru-based catalysts in yield and turnover frequency (TOF). This catalyst enables continuous NH3 production, even at 473 K under ambient pressure. During ammonia synthesis, Ru nanoparticles are distinctly anchored on the surface of Ca(NH2)(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(NH2)(2) interface. The catalytic stability is significantly improved by Ba-doping of Ca(NH2)(2), and no degradation was observed after ca. 700 h of operation.