ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Manganese doped Ceria (Ce_1−xMn_xO_2−δ (x = 0–0.3)) catalysts synthesized by EDTA–Citrate method for soot oxidation activity

Atmuri Shourya and Hari Prasad Dasari

Energy and Catalysis Materials Laboratory, Chemical Engineering Department, National Institute of Technology Karnataka, Surathkal, Mangalore, India

E-mail: energyhari@nitk.edu.in

Received: 11 April 2022  Accepted: 18 July 2022

Abstract:

Ceria–Manganese oxide catalysts (Ce_1−xMn_xO_2−δ where x = 0, 0.05, 0.1, 0.2, and 0.3, termed CM0, CM5, CM10, CM20, and CM30, respectively) were synthesized by EDTA–Citrate method, calcined at 600 °C/5 h, and checked for soot oxidation activity. The XRD spectra exhibited the cubic fluorite phase formation and complete solubility of Mn in Ceria lattice up to CM30. BET and BJH analysis showed that the surface area and pore volume had an appreciable influence on the soot oxidation activity, as seen in the case of CM5, which had superior BET surface area (50 m²/g) as well as pore volume (0.128 cc/g). The Raman spectra revealed secondary phase formation of Mn₃O₄ peak in CM20 and CM30. FESEM analysis was carried out for all the CMX samples. TEM images displayed the decrease in the particle size of CM5 with the inclusion of Manganese ions into the Ceria lattice. SAED analysis provided evidence for the polycrystalline nature of CM5 compared to CM0. Soot oxidation activity was carried out in tight contact conditions and an air atmosphere. CM5 with a T₅₀ of 360 °C had the least among the CMX catalysts. Ozawa and KAS methods were used to determine the soot oxidation activation energy. CM5 had the least activation energy with 118 kJ/mol (Ozawa) and 114 kJ/mol (KAS). High specific surface area, pore-volume, relatively higher exposed (220) and (200) planes, the lower activation energy for soot oxidation activity, high synergy, and robust interactions between Ceria and Manganese oxides were pivotal in the decrease in soot combustion temperature of the CM5 catalyst.

Graphical abstract

Keywords: Manganese doped Ceria; EDTA–Citrate method; Soot oxidation; Activation energy

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-022-02386-8

Chemical Papers 76 (11) 7095–7110 (2022)