Model heterogeneous acid catalysts and metal-support interactions: A combined surface science and catalysis study
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.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 6827194
- Report Number(s):
- LBL-32877; ON: DE93004692
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
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