氨
氧化物
离解(化学)
氧气
催化作用
材料科学
二氧化钛
氢
无机化学
分子
氧化铌
化学工程
化学
物理化学
有机化学
冶金
工程类
作者
Chengli He,Chen Yang,Zixiang Hao,Linrui Wang,Mingyan Wang,Xiaoli Cui
出处
期刊:Small
[Wiley]
日期:2024-02-17
标识
DOI:10.1002/smll.202309500
摘要
Mechanochemical ammonia (NH3 ) synthesis is an emerging mild approach derived from nitrogen (N2 ) gas and hydrogen (H) source. The gas-liquid phase mechanochemical process utilizes water (H2 O), rather than conventional hydrogen (H2 ) gas, as H sources, thus avoiding carbon dioxide (CO2 ) emission during H2 production. However, ammonia yield is relatively low to meet practical demand due to huge energy barriers of N2 activation and H2 O dissociation. Here, six transition metal oxides (TMO) such as titanium dioxide (TiO2 ), iron(III) oxide (Fe2 O3 ), copper(II) oxide (CuO), niobium(V) oxide(Nb2 O5 ), zinc oxide (ZnO), and copper(I) oxide (Cu2 O) are investigated as catalysts in mechanochemical N2 fixation. Among them, TiO2 shows the best mechanocatalytic effect and the optimum reaction rate constant is 3.6-fold higher than the TMO-free process. The theoretical calculations show that N2 molecules prefer to side-on chemisorb on the mechano-induced bridge-oxygen vacancies in the (101) crystal plane of TiO2 catalyst, while H2 O molecules can dissociate on the same sites more easily to provide free H atoms, enabling an alternative-way hydrogeneration process of activated N2 molecules to release NH3 eventually. This work highlights the cost-effective TiO2 mechanocatalyst for ammonia synthesis under mild conditions and proposes a defect-engineering-induced mechanocatalytic mechanism to promote N2 activation and H2 O dissociation.
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