Promotion Effects of Barium and Cobalt on Manganese Oxide Catalysts for Soot Oxidation
2021
Xu, Ke | Wang, Meng | Zhang, Yan | Shan, Wenpo | He, Hong
In this study, the catalytic performance of manganese-based compound catalysts and the influence of the introduction of barium and cobalt on the MnOₓ catalyst were investigated. Mn-based compound catalysts were synthesized by a simple co-precipitation method while the cobalt was loaded by wet impregnation. The 4% Co/BaMnOₓ sample exhibited the best catalytic activity and stability in soot oxidation, with a T₅₀ value of 402 °C in the 1000 ppm NO/10% O₂/N₂ gas flow. The catalysts were characterized by several analytical techniques such as XRD, BET, SEM, O₂-TPD, H₂-TPR, and XPS to reveal their physicochemical properties. The phases of catalysts changed and the crystallite sizes and crystallinity decreased after the introduction of barium and cobalt, as confirmed by the XRD, BET, and SEM results. NO-TPO experiments revealed that the loading of barium could increase the NOₓ storage capacity at low temperatures (200–380 °C) and then desorb NO₂ at 380–500 °C, and the additional desorbed NO₂ could promote the catalytic activity effectively. The characterization (H₂-TPR, O₂-TPD, and XPS) results confirmed that the redox properties of the catalyst were improved after the introduction of cobalt, which is a key factor in its excellent catalytic performance for soot combustion. Consequently, the synergistic effects of redox properties and NOₓ storage and desorption ability are key factors for improving the catalytic activity during soot combustion. This study provided rational insights into the roles of cobalt and barium in the process of soot catalytic oxidation.
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