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          Institute: Fritz-Haber-Institut     Collection: Inorganic Chemistry     Display Documents



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ID: 477779.0, Fritz-Haber-Institut / Inorganic Chemistry
Adsorption-Desorption Equilibrium Investigations of n-Butane on Nanocrystalline Sulfated Zirconia Thin Films
Authors:Lloyd, Rhys W.; Hansen, Thomas W.; Ranke, Wolfgang; Jentoft, Friederike C.; Schlögl, Robert
Language:English
Research Context:Project 3: Zirconium oxide model systems
Date of Publication (YYYY-MM-DD):2011-01-04
Title of Journal:Applied Catalysis A
Journal Abbrev.:Appl. Catal. A
Volume:391
Issue / Number:1-2
Start Page:215
End Page:224
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:Nanocrystalline thin films of the alkane skeletal isomerisation catalyst sulfated zirconia were successfully deposited on a silicon substrate in order to allow the application of surface science techniques. Thermal treatment of the films was optimised to chemically mimic the powder preparation process, resulting in films possessing the essential features (including tetragonal phase, nanocrystallinity and sulfur content of not, vert, similar3 at.%) of active powder catalysts. The n-butane adsorption–desorption equilibrium under isobaric conditions (10−8–10−6 h Pa) over the temperature range 300–100 K was monitored by photoelectron spectroscopy. Analysis of the isobars revealed strong and weak n-butane chemisorption sites, releasing heats of between 59–40 and 47–34 kJ/mol, corresponding to 5 and 25% of a monolayer coverage, respectively. The total amount of chemisorbed n-butane coincides with the estimated number of surface sulfate groups. An increase in adsorption heat was observed between coverages of not, vert, similar5–8% of a monolayer, indicating adsorbate–adsorbate interactions. It follows that adjacent sites are present and isomerisation by a bimolecular surface reaction is feasible. Physisorption on the films generates heats of not, vert, similar28 kJ/mol, for coverages from 30% up to a complete monolayer. Multilayer adsorption results in the formation of an electrically insulating adsorbate structure. It is proposed that the strong chemisorption sites correspond to an interaction with a minority disulfate species.
Free Keywords:Sulfated Zirconia Thin Films; n-butane;
External Publication Status:published
Document Type:Article
Communicated by:Robert Schlögl
Affiliations:Fritz-Haber-Institut/Inorganic Chemistry/Functional Characterization
Fritz-Haber-Institut/Inorganic Chemistry/Surface Analysis
Fritz-Haber-Institut/Inorganic Chemistry/Inorganic Chemistry
Identifiers:URL:http://dx.doi.org/10.1016/j.apcata.2010.06.028 [only for subscriber]
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