Water-promoted low-concentration NO removal at room temperature by Mg-doped manganese oxides OMS-2

• OMS-2 materials show higher catalytic activity in removing of NO at room temperature.
• The NO removal performance of OMS-2 materials can be enhanced through doping Mg ions.
• The catalytic activity of OMS-2 can be greatly promoted when water vapor is involved.

Nanostructured magnesium doped manganese oxides (Mg-SC-OMS-2) was prepared through doping Mg into OMS-2 using an ultrasound-assisted approach. This Mg-SC-OMS-2 material showed low crystallinity with a large surface area and extensive defects which are totally different from those synthesized by conventional method. Extraordinarily high NO removal performance was obtained. It retained 99% NO removal ratio for as long as 8 h under extremely high space velocity of 120,000 mL/g/h. More attractively, when water vapor was introduced, above 50% removal ratio of catalyst was maintained for as long as 250 h. The high catalytic activity of Mg-SC-OMS-2 is associated with presence of redox pair Mn3+/Mn4+ and activated oxygen species at oxygen vacancies occurring via the pathway of Mars-van Krevelen mechanism.

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