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Effects of cage shape and size of 8-membered ring molecular sieves on their deactivation in methanol-to-olefin (MTO) reactions

Paper ID Volume ID Publish Year Pages File Format Full-Text
43277 45961 2008 9 PDF Available
Title
Effects of cage shape and size of 8-membered ring molecular sieves on their deactivation in methanol-to-olefin (MTO) reactions
Abstract

Four kinds of 8-membered ring (8-MR) small-port molecular sieves with CHA (SAPO-34), ERI (UZM-12), LTA (UZM-9), and UFI (UZM-5) topologies were prepared to investigate the effects of the cage shape and the cage size on their catalytic activities and on deactivation behaviors in methanol-to-olefin (MTO) reactions. UZM-5, -9, and -12 zeolites with Si/Al molar ratios of 5–6 showed high initial activities in the MTO reaction owing to their sufficient acidities, and they were highly selective to lower olefins such as SAPO-34 molecular sieve. However, they were rapidly deactivated in the order of CHA < LTA < ERI < UFI. The UV–VIS and NMR spectroscopy examinations of the materials accumulated in the cages of the 8-MR catalysts indicated that the concentration of large fused polycyclic aromatics was high in the cages of an easily deactivated 8-MR catalyst. The selective and stable catalytic performance of SAPO-34 molecular sieve in the MTO reaction is explained by the suitable shape and size of its cages, which are thus capable of preserving stably the active intermediates, multialkyl benzenes. They are also capable of suppressing the formation of fused polycyclic aromatics that would cause its deactivation.

Graphical abstractSmall-port molecular sieves with CHA, ERI, LTA, and UFI topologies were prepared to investigate the effects of the cage shape and the cage size on their catalytic activities and on their deactivation behaviors in MTO reactions. The materials occluded in their cages are different according to their topologies as shown in their UV–VIS spectra, indicating the effects of cage shape and size on their deactivation behaviors.Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Methanol to olefin; 8-MR molecular sieve; CHA; ERI; LTA; UFI; Deactivation; Cage shape and size
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Effects of cage shape and size of 8-membered ring molecular sieves on their deactivation in methanol-to-olefin (MTO) reactions
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 339, Issue 1, 15 April 2008, Pages 36–44
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us