FTIR study of low-temperature CO adsorption on Mn-ZSM-5 and MnY zeolites. Effect of the zeolite matrix on the formation of Mn2+(CO)x geminal species

Date

2002-08

Authors

Hadjiivanov, K.
Ivanova, E.
Kantcheva, M.
Ciftlikli, E. Z.
Klissurski, D.
Dimitrov, L.
Knözinger, H.

Editor(s)

Advisor

Supervisor

Co-Advisor

Co-Supervisor

Instructor

BUIR Usage Stats
1
views
4
downloads

Citation Stats

Series

Abstract

Adsorption of CO on Mn-ZSM-5 zeolite at 85 K results in formation of physically adsorbed CO, several kinds of H-bonded CO and Mn2+ (CO)(x) geminal species (2202 cm(-1)). Decreasing the coverage during evacuation results in disappearance of the physically adsorbed CO and the H-bonded forms and in conversion of the dicarbonyls to linear Mn2+-CO Species (2214 cm(-1)). The latter are quite stable at 85 K. Coadsorption (CO)-C-12 and (CO)-C-13 reveals that the CO molecules in the geminal polycarbonyls behave as independent oscillators. In contrast, CO adsorption at 85 K on MnNaY zeolite only leads to formation of linear Mn2+-CO species (2210 cm-1) and mono- and di-carbonyls associated with residual sodium cations. The results are interpreted as evidence that site-specified geminal carbonyls are formed with cations possessing an ionic radius bigger than a critical value. This value is different for different positions in various zeolites and is bigger for cations in S-II positions in Y zeolites than is the case of cations in a ZSM-5 matrix. (C) 2002 Elsevier Science B.V. All rights reserved.

Source Title

Catalysis Communications

Publisher

Elsevier

Course

Other identifiers

Book Title

Degree Discipline

Degree Level

Degree Name

Citation

Published Version (Please cite this version)

Language

English