催化作用
吸附
选择性催化还原
化学
活化能
基础(拓扑)
无机化学
化学工程
作者
Xiaolei Hu,Weiye Qu,Junxiao Chen,Dongrun Xu,Jing Liu,Yangyang Dong,Rui Liu,Zhen Ma,Xingfu Tang
标识
DOI:10.1016/j.cej.2022.135832
摘要
• A highly active Ce-W/TiO 2 NH 3 -SCR catalyst with reactants-coupling dual sites was designed. • The highly dispersed W and Ce served as the acid-base pairs responsible for adsorbing NH 3 and NO x simultaneously . • The adsorbed NH 3 and NO x reacted along a low-activation-energy pathway via a Langmuir-Hinshelwood mechanism. Selective catalytic reduction (SCR) of NO x with NH 3 over V 2 O 5 -based catalysts has been widely used to control NO x emissions from power plants, but its application is largely limited in other industrial boilers because of insufficient catalytic efficiency at low temperatures. Here we resolve this problem by mechanistically designing a highly active Ce-W/TiO 2 catalyst with reactants-coupling dual catalytic sites. The results demonstrate that W and Ce are highly dispersed on the surfaces of Ce-W/TiO 2 to form dual catalytic sites, which act as acid-base pairs favorable for NH 3 and NO adsorption, respectively, thereby allowing the reaction of adsorbed NH 3 on the W site with oxidized NO species (NO 3 − ) adsorbed on the adjacent Ce site to proceed along a low-activation-energy pathway via Langmuir-Hinshelwood mechanism. Compared with Ce/TiO 2 , a W-Ce synergy gives rise to more abundant Ce 3+ on Ce-W/TiO 2 , which facilitates the activation of O 2 during SCR process, thus improving the low-temperature SCR performance. Therefore, the design of the dual catalytic sites based on the properties of reactants provides an alternative approach to developing highly active SCR catalysts.
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