Alkali metal-enhanced cerium manganese-based three-dimensional ordered macroporous catalyst for NO oxidation and soot combustion

Abstract

Alkali metals can control the redox potential of a reaction system as well as modify the surface electronic structure and improve the stability of a catalyst. Herein, we doped an alkali metal into a cerium manganese-based three-dimensional ordered macroporous (3DOM) catalyst for NO oxidation and soot combustion; the doping was achieved using a self-sacrificing polymethyl methacrylate template and an excess impregnation method. The introduction of alkali metals can provide a rough pore surface, which increases the contact area between the catalyst and the reactant gas. Meanwhile, alkali metal doping can promote the formation of more oxygen vacancies and unsaturated structures and increase the catalytic activity for NO oxidation and soot combustion. 5% K-doped CM-5K achieved an NO conversion rate of 81.9% at 250 °C and of nearly 100% at 320 °C. CM-5K also demonstrated remarkable stability in cycling stability tests for NO oxidation and soot combustion. This work provides a promising catalyst candidate for NO oxidation and soot combustion in practical application.