Diesel Soot Combustion over Mn2O3 Catalysts with Different Morphologies: Elucidating the Role of Active Oxygen Species in Soot Combustion

• Published in: Chemistry, an Asian journal Vol. 15; no. 13; pp. 2005 - 2014
• Main Authors: Kuwahara, Yasutaka, Kato, Genki, Fujibayashi, Akihiro, Mori, Kohsuke, Yamashita, Hiromi
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.07.2020
• Subjects: Active oxygen species; Carbon; Carbon soot combustion; Catalysts; Chemical synthesis; Chemistry; Combustion; Manganese oxide; Manganese oxides; Microscopy; Morphology; Oxidation; Oxygen; Oxygen vacancy; Particulate matter; Photoelectrons; Scanning electron microscopy; Scanning transmission electron microscopy; Soot; Active oxygen species; Particulate matter; Carbon soot combustion; Manganese oxide; Oxygen vacancy
• ISSN: 1861-4728; 1861-471X
• DOI: 10.1002/asia.202000461

Catalytic diesel soot combustion was examined using a series of Mn2O3 catalysts with different morphologies, including plate, prism, hollow spheres and powders. The plate‐shaped Mn2O3 (Mn2O3‐plate) exhibited superior carbon soot combustion activity compared to the prism‐shaped, hollow‐structured and powdery Mn2O3 under both tight and loose contact modes at soot combustion temperatures (T50) of 327 °C and 457 °C, respectively. Comprehensive characterization studies using scanning electron microscopy, scanning transmission electron microscopy, X‐ray diffraction, X‐ray photoelectron spectroscopy, temperature‐programmed reduction and oxygen release measurements, revealed that the improved activity of Mn2O3‐plate was mainly attributed to the high oxygen release rate of surface‐adsorbed active oxygen species, which originated from oxygen vacancy sites introduced during the catalyst preparation, rather than specific surface‐exposed planes. The study provides new insights for the design and synthesis of efficient oxidation catalysts for carbon soot combustion as well as for other oxidation reactions of harmful hydrocarbon compounds. A series of Mn2O3 catalysts with controlled morphologies were synthesized and examined in carbon soot combustion. Plate‐shaped Mn2O3 composed of polycrystalline Mn2O3 with plenty of oxygen vacancies exhibited improved soot combustion performance compared with conventional powdery Mn2O3. The improved catalytic activity was mainly attributed to the increased concentration of active surface‐adsorbed oxygen species.