Abstract

NO_x is one of the most detrimental pollutants to the atmospheric and ecological environment. Currently, selective catalytic reduction (SCR) of NO_x by NH₃ was conducted by transition metals-doped (Mo, Ce, Cu, Fe, W, and Zr, including P) TiO₂ catalysts through orthogonal experimental design. It was found that Mo, Cu, Fe, and Zr significantly affected the catalytic activity, while Mo showed the highest impact. The optimum amounts of Mo, Ce, Cu, Fe, W, P, and Zr were 1.5 wt%, 2 wt%, 6 wt%, 4 wt%, 0 wt%, 0.9 wt%, and 4 wt%, respectively. The catalysts’ redox properties and adsorption capacity for NO were key factors affecting the catalytic activity. Proper amounts of adsorbed oxygen, together with appropriate adsorption capacity for NO and acidity distribution, were beneficial for the formation of intermediates. The mechanistic cause of the promoting effect of metal oxides for NH₃-SCR was studied using in situ DRIFTS. These results revealed that the addition of metal oxides is to promote the adsorption and activation of NH₃ on the catalyst surface, which is beneficial for the promotion of SCR activity.

Graphic abstract

Promoting effect of multi-transition metals was confirmed for the selective catalytic reduction of NO by NH₃ over TiO₂ following the order of Mo > Fe ≈ Zr > Cu > W>P > Ce.

中文翻译：

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原位DRIFTS研究多过渡金属对TiO 2催化剂上NH 3还原NO的促进作用

摘要

NO _x是对大气和生态环境最有害的污染物之一。目前，选择性催化还原（SCR）的NO _X由NH ₃通过过渡金属掺杂（钼，铈，铜，铁，W，和Zr，其中P）的TiO进行₂通过正交实验设计催化剂。发现Mo，Cu，Fe和Zr显着影响催化活性，而Mo显示出最大的影响。Mo，Ce，Cu，Fe，W，P和Zr的最佳量分别为1.5重量％，2重量％，6重量％，4重量％，0重量％，0.9重量％和4重量％。催化剂的氧化还原性能和对NO的吸附能力是影响催化活性的关键因素。适量的吸附氧，以及对NO和酸度分布的适当吸附能力，对中间体的形成是有利的。利用原位DRIFTS研究了金属氧化物促进NH ₃ -SCR作用的机理。这些结果表明，添加金属氧化物是为了促进NH ₃的吸附和活化。 在催化剂表面上，这有利于促进SCR活性。

图形摘要

证实了Mo_Fe≈Zr> Cu> W> P> Ce的顺序，多过渡金属对NH ₃在TiO _2上选择性催化还原NO的促进作用。