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Title: Model heterogeneous acid catalysts and metal-support interactions: A combined surface science and catalysis study

Abstract

This (<100 [Angstrom]) silica-alumina layers were tested as potential model heterogeneous acid catalysts for combined surface science and catalysis studies. Three preparation methods were used: oxidation of r3 [times] r3 R30 Al/Si(111) structure in UHV; deposition on Si(lll) from aqueous solution; and argon ion beam sputter deposition in UHV. The homogeneous thin layers are amorphous, and the chemical environment of surface atoms is similar to that of Si, Al and oxygen atoms on high surface area acid catalysts. Since the ion beam-deposited thin layer of silica-alumina has the same composition as the target zeolite this deposition method is a promising tool to prepare model catalysts using practical catalyst targets. The silica-alumina layers are active in cumene cracking, a typical acid catalyzed reaction. In order to clearly distinguish background reactions and the acid catalyzed reaction at least 20 cm[sup 2] catalyst surface area is needed. Two series of model platinum-alumina catalysts were prepared in a combined UHV -- high pressure reactor cell apparatus by depositing alumina on polycrystalline Pt foil and by vapor depositing Pt on a thin alumina layer on Au. Both model surfaces have been prepared with and without chlorine. AES, CO desorption as well as methyl cyclopentane (MCP)more » hydrogenolysis studies indicate that the Pt surface area is always higher if a chlorination step is involved. Selectivity patterns in MCP ring opening on Pt-on-alumina'' and on alumina-on-Pt'' are different; only the former is a linear combination of selective and statistical ring opening. Product distribution, however, changes with coverage and reaction time. The properties of the two model catalyst systems and role of chlorine in MCP hydrogenolysis are also discussed.« less

Authors:
Publication Date:
Research Org.:
Lawrence Berkeley Lab., CA (United States)
Sponsoring Org.:
DOE; USDOE, Washington, DC (United States)
OSTI Identifier:
6827194
Alternate Identifier(s):
OSTI ID: 6827194; Legacy ID: DE93004692
Report Number(s):
LBL-32877
ON: DE93004692
DOE Contract Number:  
AC03-76SF00098
Resource Type:
Technical Report
Resource Relation:
Other Information: Thesis (Ph.D.)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ALUMINIUM OXIDES; CATALYTIC EFFECTS; CATALYSTS; CUMENE; CRACKING; CYCLOALKANES; HYDROGENATION; PLATINUM; SILICON OXIDES; CATALYST SUPPORTS; CHLORINATION; HETEROGENEOUS CATALYSIS; LAYERS; LEWIS ACIDS; REGENERATION; THIN FILMS; ALKANES; ALUMINIUM COMPOUNDS; AROMATICS; CATALYSIS; CHALCOGENIDES; CHEMICAL REACTIONS; DECOMPOSITION; ELEMENTS; FILMS; HALOGENATION; HYDROCARBONS; HYDROGEN COMPOUNDS; INORGANIC ACIDS; METALS; ORGANIC COMPOUNDS; OXIDES; OXYGEN COMPOUNDS; PLATINUM METALS; PYROLYSIS; SILICON COMPOUNDS; THERMOCHEMICAL PROCESSES; TRANSITION ELEMENTS 400201* -- Chemical & Physicochemical Properties

Citation Formats

Boszormenyi, I. Model heterogeneous acid catalysts and metal-support interactions: A combined surface science and catalysis study. United States: N. p., 1991. Web. doi:10.2172/6827194.
Boszormenyi, I. Model heterogeneous acid catalysts and metal-support interactions: A combined surface science and catalysis study. United States. doi:10.2172/6827194.
Boszormenyi, I. Wed . "Model heterogeneous acid catalysts and metal-support interactions: A combined surface science and catalysis study". United States. doi:10.2172/6827194. https://www.osti.gov/servlets/purl/6827194.
@article{osti_6827194,
title = {Model heterogeneous acid catalysts and metal-support interactions: A combined surface science and catalysis study},
author = {Boszormenyi, I.},
abstractNote = {This (<100 [Angstrom]) silica-alumina layers were tested as potential model heterogeneous acid catalysts for combined surface science and catalysis studies. Three preparation methods were used: oxidation of r3 [times] r3 R30 Al/Si(111) structure in UHV; deposition on Si(lll) from aqueous solution; and argon ion beam sputter deposition in UHV. The homogeneous thin layers are amorphous, and the chemical environment of surface atoms is similar to that of Si, Al and oxygen atoms on high surface area acid catalysts. Since the ion beam-deposited thin layer of silica-alumina has the same composition as the target zeolite this deposition method is a promising tool to prepare model catalysts using practical catalyst targets. The silica-alumina layers are active in cumene cracking, a typical acid catalyzed reaction. In order to clearly distinguish background reactions and the acid catalyzed reaction at least 20 cm[sup 2] catalyst surface area is needed. Two series of model platinum-alumina catalysts were prepared in a combined UHV -- high pressure reactor cell apparatus by depositing alumina on polycrystalline Pt foil and by vapor depositing Pt on a thin alumina layer on Au. Both model surfaces have been prepared with and without chlorine. AES, CO desorption as well as methyl cyclopentane (MCP) hydrogenolysis studies indicate that the Pt surface area is always higher if a chlorination step is involved. Selectivity patterns in MCP ring opening on Pt-on-alumina'' and on alumina-on-Pt'' are different; only the former is a linear combination of selective and statistical ring opening. Product distribution, however, changes with coverage and reaction time. The properties of the two model catalyst systems and role of chlorine in MCP hydrogenolysis are also discussed.},
doi = {10.2172/6827194},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1991},
month = {5}
}