Important factors of the A-site deficient Mn perovskites design affecting the CO oxidation activity

• Published in: Catalysis today Vol. 425; p. 114347
• Main Authors: Mane, Rasika, Kim, Heesu, Han, Kyeongwon, Kim, Hyungjin, Lee, Sang Soo, Roh, Hyun-Seog, Lee, Chanmin, Jeon, Yukwon
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2024
• Subjects: A-site deficient perovskites; Chemical structure; CO oxidation; Mn content; Mn content; CO oxidation; A-site deficient perovskites; Chemical structure
• ISSN: 0920-5861; 1873-4308
• DOI: 10.1016/j.cattod.2023.114347

A-site deficient La0.4Sr0.4MnxTi1−xO3 (LSMT, x = 0, 0.4, 0.6, 0.8) perovskites were investigated for their structural change and effect on CO oxidation activity. The XRD, XPS, TPR and O2-TPD analysis represent the change in Mn concentration, known as an active species in oxidation, affecting the crystal structure, oxidation state of the B-site cation (Mn), number of oxygen vacancies, and the reducibility of the catalysts. The shift in the main perovskite diffraction peak in XRD spectra of the perovskites with a change in Mn content represents the formation of cationic vacancies. At the lower temperature (<200 oC), CO oxidation efficiency of LSMT perovskite catalysts was found to be almost identical. This can be attributed to their similar perovskite structure and surface area. Compared to the higher temperature (>200 oC) CO oxidation activity, the LSMT catalyst with lower Mn content of 0.4 shows relatively better performance than the higher Mn content samples, which signifies the active role of the Mn oxidation state and lattice oxygen species of the perovskite catalysts. Moreover, the LSMT4446 catalyst shows stable activity for more than 12 h with an average CO conversion of 80 %. From these results, we found that the factors of the Mn oxidation state and the type of oxygen species are crucial when designing an Mn-based perovskite catalyst for catalytic applications. [Display omitted] •Structural change in the A-site deficient Ti perovskites by different Mn doping.•Change in Mn content influencing surface composition of Mn and O species.•Higher high temperature activity of relatively lower Mn content LSMT catalyst.•CO oxidation performance data represent the involvement of lattice oxygen species.