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

Dip coating of ceria–manganese mixed oxides on cordierite and its CO oxidation activity

Atmuri Shourya, Hari Prasad Dasari, and Aasif Ahmad Wagay

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

E-mail: energyhari@nitk.edu.in

Received: 21 December 2023  Accepted: 8 April 2024

Abstract:

Dip coating method was utilized for wash-coating alumina onto cordierite honeycomb substrate, followed by catalyst coating by sol–gel dip coating of CMX(X = 0, 5, 70, and 100 corresponding to Ce_1-xMn_xO_2-δ, where x = 0, 0.5, 0.7, and 1) to obtain CM0/Al₂O₃/Cord, CM5/Al₂O₃/Cord, CM70/Al₂O₃/Cord, and CM100/Al₂O₃/Cord. The sol–gel was obtained from the EDTA–citrate method. XRD, BET, and BJH analysis was conducted on samples Cord to CM100/Al₂O₃/Cord. An intense peak of ceria at 462.53 cm⁻¹ and that of Mn₃O₄ was observed at 658 cm⁻¹ in the Raman spectra analysis. The adherence test was conducted to test the mechanical stability of the wash-coat and catalyst layer. The visual evidence of coating was furnished by optical imaging and FESEM analysis. Ultrafine particles with high porosity were observed in sample Al₂O₃/Cord. Cracks were observed in the FESEM images of CM0/Al₂O₃/Cord to CM100/Al₂O₃/Cord samples. CO oxidation studies were performed on the samples Cord to CM100/Al₂O₃/Cord. CM70/Al₂O₃/Cord performed the best among all other samples with a T₅₀ temperature of 157 °C. The activation energy of CO oxidation was calculated using the Ozawa method for samples CM0/Al₂O₃/Cord to CM100/Al₂O₃/Cord. 50 h long-term CO oxidation stability experiments were also conducted on samples CM0/Al₂O₃/Cord to CM100/Al₂O₃/Cord. The synergistic effects of ceria and manganese, combined with fine dispersion of the catalyst, pore characteristics, and cracks improving diffusivity, pitched CM70/Al₂O₃/Cord to have the best CO oxidation activity.

Keywords: Dip coating; Cordierite; EDTA–citrate method; Ceria–manganese mixed oxides; CO oxidation

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-024-03457-8

Chemical Papers 78 (8) 5113–5129 (2024)