Enhancement of the Yield of Ammonia by Hydrogen‐Sink Effect during Plasma Catalysis
Enhancement of the Yield of Ammonia by Hydrogen‐Sink Effect during Plasma Catalysis
复制标题
等离子体催化过程中氢汇效应提高氨产率
DOI：
10.1002/cctc.201901769
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发表时间：
2019
期刊：
影响因子：
4.5
通讯作者：
Carreon, Maria L.
中科院分区：
文献类型：
--
作者：
Shah, Javishk;Gorky, Fnu;Psarras, Peter;Seong, Bomsaerah;Gómez‐Gualdrón, Diego A.;Carreon, Maria L.
等离子体催化合成氨早在20世纪初就已为人所知，但直到现在才开始努力优化用于这一目的的催化剂。在这里，我们研究了各种过渡金属、低熔点金属和富镓合金催化剂在等离子体环境下产生氨的活性。镍、锡和金是目前工业氨合成中不常用的纯金属催化剂。这些催化剂的氨收率分别为34%、29%和19%。当使用合金时，发现了协同效应，因为一些合金的产率比其组成金属高25 - 50%。所使用的金属被分为两类。第一类金属（Cu, Ag， Au和Fe），它们是疏氮的（不包括Fe， Haber - Bosch催化剂）和较差的氢汇。对于这些金属，测得的气相Hα浓度与氨产率呈负相关，而与催化剂表面H结合强度呈正相关。第二类金属（Ga、In、Sn和Ni）具有较好的吸氢能力，其气相中h α的浓度往往低于第一类金属，这与它们预期的吸氢行为相一致。对于这些金属，h α的浓度与氨收率相关。等离子体表征实验和DFT计算表明，Ni和Sn的更高性能与溶解氢减缓H重组的好处有关，这是一个可以在未来的研究中通过合理改变催化剂组成来优化的特征。
Plasma‐catalytic ammonia synthesis has been known since the early 1900s, but only until now efforts to optimize catalysts for this purpose are emerging. Here, we investigate various transition metals, low‐melting‐point metals, and gallium‐rich alloy catalysts for their activity towards ammonia production under a plasma environment. The best three pure metal catalysts were Ni, Sn and Au, which are not traditional catalysts for the current industrial ammonia synthesis. The ammonia yields for these catalysts were 34 %, 29 %, and 19 %, respectively. Synergistic effects were detected when employing alloys, as some alloys presented ∼25–50 % higher yields than their constituent metals. The employed metals were classified into two categories. Category I metals (Cu, Ag, Au and Fe), which are nitrophobic (excluding Fe, the Haber‐Bosch catalyst) and poor hydrogen sinks. For these metals, the measured concentration of Hαin the gas phase tended to correlate inversely with ammonia yield and directly with the H binding strength on the catalyst surface. Category II metals (Ga, In, Sn and Ni), which are good hydrogen sinks, tend to have a lower concentration of Hαin the gas phase than that of category I metals, which is consistent with their expected sink behavior. For these metals, the concentration of Hαcorrelates with ammonia yield. Plasma characterization experiments and DFT calculations suggest that the higher performance of Ni and Sn is related to the benefit of dissolving hydrogen to slow down H recombination, which is a feature that could be potentially optimized in future studies by rationally altering the catalyst composition.
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DOI：
--
发表时间：
2009
期刊：
影响因子：
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影响因子：
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作者：
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发表时间：
1972
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影响因子：
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作者：
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