Mechanistic Insights into the Zeolite-Catalyzed Isomerization and Disproportionation of m-Xylene
SCIE
SCOPUS
- Title
- Mechanistic Insights into the Zeolite-Catalyzed Isomerization and Disproportionation of m-Xylene
- Authors
- Min, HK; Cha, SH; Hong, SB
- Date Issued
- 2012-06
- Publisher
- AMERICAN CHEMICAL SOCIETY
- Abstract
- The mechanisms of m-xylene isomerization and disproportionation over 13 medium-pore zeolites and three large-pore ones are investigated. While H-TNU-10 and H-ZSM-57 with intersecting 10- and 8-ring channels were found to show considerably higher p/o ratios than H-ZSM-S, a commercial m-xylene isomerization catalyst, the GC-MS results from used zeolite catalysts demonstrate the intrazeolitic build-up of tri- and tetramethylated diphenylmethane species, whose existence during the m-xylene transformation over any acidic catalyst has not been experimentally verified until now. These dicyclic aromatic compounds were ascertained to serve as reaction intermediates of bimolecular m-xylene isomerization within the micropores not only of large-pore zeolites but also of medium-pore materials at temperatures lower than 523 K or so, once there are internal void spaces larger than 10-rings. Flushing experiments with used zeolites followed by GC-MS analyses strongly suggest that the high p-xylene selectivity found in some medium-pore zeolites is largely due to product shape selectivity rather than to transition state one. More importantly, the overall GC-MS results of our work demonstrate that transition state and product shape selectivities are experimentally distinguishable from each other.
- Keywords
- zeolites; m-xylene isomerization; shape selective catalysis; transition states; GC-MS; reaction mechanism; LARGE-PORE ZEOLITES; HIGH-SILICA ZEOLITE; ETHYLBENZENE DISPROPORTIONATION; SHAPE SELECTIVITY; COKE FORMATION; META-XYLENE; TOPOLOGY; TRANSFORMATION; FRAMEWORK; NU-87
- URI
- https://oasis.postech.ac.kr/handle/2014.oak/16412
- DOI
- 10.1021/CS300127W
- ISSN
- 2155-5435
- Article Type
- Article
- Citation
- ACS CATALYSIS, vol. 2, no. 6, page. 971 - 981, 2012-06
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- There are no files associated with this item.
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