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Selective poisoning of active centers of sulfated zirconia monitored by TAP, XPS, and DRIFTS

Paper ID Volume ID Publish Year Pages File Format Full-Text
43946 45997 2006 8 PDF Available
Title
Selective poisoning of active centers of sulfated zirconia monitored by TAP, XPS, and DRIFTS
Abstract

Temporal analysis of products (TAP), XPS, and DRIFTS were used to study the activity and deactivation of acid sites on a sulfated zirconia catalyst for the n-butane isomerization. The activity of the catalyst was altered by selective poisoning of active centres by sulfation with sodium sulfate under the condition of a constant surface sulfate content. Depending on the surface sodium concentration the Brønsted acid sites were selectively poisoned, which was reflected by a stepwise decrease in the isomerization activity and an altered Brønsted-to-Lewis acid ratio. It could be shown, that only a very small amount of Brønsted acid sites were responsible for the initiation of the catalytic reaction. TAP measurements revealed that with a decreasing number of available strong Brønsted sites, the adsorption of the reactant on the surface dramatically decreased. The altered adsorption surface places prevented the formation of reactive intermediates which seemed to be necessary to start the isomerization reaction cycle. The samples were additionally characterized by N2-physisorption, X-ray diffraction, and temperature programmed desorption of ammonia. Moreover, the number of Brønsted sites was estimated by a solid-phase exchange of sulfated zirconia with NH4Y zeolite which could be directly correlated to the DRIFTS results.

Keywords
Sulfated zirconia; n-Butane isomerization; Active centres; Selective poisoning; TAP; XPS; DRIFTS
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Selective poisoning of active centers of sulfated zirconia monitored by TAP, XPS, and DRIFTS
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 301, Issue 1, 10 February 2006, Pages 1–8
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