Characterization and kinetics studies over supported monometallic and mixed metal catalysts /
The electronic, morphological, and chemical properties of
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1996.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=739363631&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | The electronic, morphological, and chemical properties of several mono-, bi-, and trimetallic model catalysts were studied using the tools of modem surface science. Trimetallic systems prepared by the vapor deposition in UHV of monolayers of two different metals (Cu, Pd, Au, Ag) onto Mo(110) and Ru(0001) single crystals have been studied using X-ray photoelectron spectroscopy (XPS) and ion scattering spectroscopy (ISS), with the goal of elucidating the electronic interactions between the dissimilar metals by measuring the core-level shifts (CLS's). Because the dissimilar second layer can be resolved from the bulk substrate with XPS, this approach allows the CLS's for the first and second layer to be monitored without the employment of a synchrotron radiation source. ISS was employed, allowing those systems which existed as discrete separate overlayers at room temperature to be identified and treated as such in applying surface corrections to the core- level binding energies (CLBE's). The CLS's in the Cu(I.0 ML)/Pd(I.0 ML)/Mo(110) and Cu(I.0 ML)/Pd(I.0 ML)/Ru(0001) systems were compared and discussed with reference to theoretical studies that indicate charge migration to the interstitial interface region upon the formation of the bimetallic bond. Alloying behavior among several other systems is investigated. The chemisorptive behavior of CO on several planar model supported Pd, Cu, and Au catalysts was studied using infrared reflection absorption spectroscopy (IRAS). For the Pd/Al2O3/Ta(l10) catalyst, the morphology of the larger Pd particles (- 70 A ) was found to be dominated by < I I I > and < I 00> facets while the smaller particles (- 25 A) displayed a larger fraction of low coordinated defect sites that are related to an enhanced activity for CO dissociation. Additionally, a study of the reaction kinetics of the CO + NO reaction over Pd catalysts was undertaken utilizing a combined approach that correlates single crystal, planar model supported catalyst, and more conventional high surface area powder catalyst results to characterize the reaction. Correlations between supported catalysts and single crystals were found in observed structural dependencies favoring more closed surfaces for reaction activity. Temperature programmed desorption (TPD) and XPS results indicate the formation and stabilization of an inactive Na species on the more open surfaces that inhibits the reaction. |
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| Item Description: | Vita. "Major Subject: Chemistry". |
| Physical Description: | xvii, 202 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 187-196. |