Preparation,characterization and NO/NO₂ catalytic reduction performance of MnO₂-Fe₂O₃-CeO₂/Al₂O₃ nanocatalysts with different manganese contents

Abstract

Reducing NOx emission in the exhaust gas under the extremely low temperature of engine cold start was important for the ecological environment and human health.MnO2 has high catalytic activity for NOx in the low temperature range, which is a promising nanocatalyst.The intrinsic relationship between the surface structural characteristics and denitrification activity of MnO2-Fe2O3-CeO2/Al2O3 nanocatalysts produced by ultrasonic assisted coprecipitation method with different manganese contents was discussed. The results show that when the manganese content is 15%(mass fraction), the nanocatalyst has the largest specific surface area and the smallest grain size. At the same time, the distribution of active substances is the most uniform. Meanwhile, the crystallinity of metal oxides is suppressed, and Mn, Fe and Ce are in the best coexistence state, which can promote the enrichment of chemisorption oxygen. The catalytic oxidation of NO to NO2 improves the reaction rate of fast SCR, and the NO2 conversion reaches 88.5% at 50 ℃. Optimizing manganese content is an extremely effective method to improve the structure-activity relationship of catalytic materials and promote the performance of NO preoxidation and fast SCR reaction.

Keywords

• manganese oxide
• nitrogen oxide
• iron oxide
• nanocatalyst
• ceo₂
• al₂o₃