Highly disordered MnOx catalyst for NO oxidation at medium–low temperatures

Abstract

Recently, the selective catalytic oxidation of NO (NO-SCO) has garnered significant surge of interest because of its pivotal role in many deNOx techniques. Particularly, NO-SCO at moderate to low temperatures ranging from 100 °C to 200 °C has garnered increasing attention, as in certain industries such as steel, cement and glass, the flue gas temperature typically falls within the range of 100 °C to 200 °C. Manganese oxides (MnOx) have emerged as promising NO-SCO catalysts, mainly due to their notable activity in NO-SCO, affordability, and environmental friendliness. However, their NO-SCO performance at medium–low temperatures of 100–200 °C is unsatisfactory. Given that introducing oxygen vacancies (OVs) into MnOx to increase the concentration of surface chemisorbed oxygen (Oads) could be a potential approach to enhance its NO-SCO performance, herein, two disordered MnOx catalysts enriched with abundant OVs were synthesized via simple thermal decomposition of manganese oxalate (MnOx-O) and manganese carbonate (MnOx-C) in air. Characterization results demonstrate that both MnOx-O and MnOx-C catalysts exhibited higher NO-SCO performance than the benchmark γ-MnO2 catalyst within the temperature range of 100–200 °C, and the disordered structure and the associated beneficial properties of MnOx-O and MnOx-C were believed to contribute to their excellent NO-SCO performance. This study provides a novel approach for synthesizing MnOx catalysts with high NO-SCO performance at medium–low temperatures of 100–200 °C.