Surface science and catalytic studies of hydrocarbon skeletal rearrangements: The platinum and the bimetallic platinum-rhenium single crystal systems
Bimetallic surfaces were prepared by vapor deposition of Re onto Pt(111) and Pt(100), and of Pt onto Re(0001) and polycrystalline Re foils. Re was found to grow layer by layer on both Pt(111) and Pt(100); it formed an hexagonal close-pack hcp film on Pt(111) and a film on Pt(100). Pt was found to grow layer by layer on Re(0001) with the formation of an hcp film. Evidence for an electronic interaction between the two metals was shown by XPS because the 4f/sub 7/2/ peaks shifted to higher binding energies for both metals when Re was deposited on Pt. The addition of Re metal to Pt(111) caused a 4 to 8 kJ/mole decrease of the metal-hydrogen bond strength. Surfaces composed of between 0.2 to 0.35 monolayers of Re on Pt(111) displayed maximum low pressure adsorption capacities for H/sub 2/ and CO. Maximum rates of hydrogenolysis for reactions near atmospheric pressure were observed from all hydrocarbons studied and were obtained over bimetallic surfaces composed of Re and Pt in an atomic ratio of 2:1. Compared to a monometallic Pt(111) surface, 0.3 monolayers of Re on Pt(111) gave a surface that was as active as a clean Re(0001) surface for ethane hydrogenolysis, yet the hydrogen partial pressure dependence observed was closest to that obtained for Pt(111). An enhancement in the production rate of aromatics from n-hexane and cyclohexane indicates that Pt atoms with Re ligands are more active than monometallic Pt for this class of reactions. The isomerization rate of n-hexane was smaller in the presence of Re than on clean Pt due to decreased desorption of ring opening products from cyclic intermediates on the bimetallic surface. However, cyclization activity was not strongly effected by the addition of Re to Pt. The presence of Re on Pt resulted in a surface more resistant toward carbonaceous deposits.73 figs., 22 tabs.
- Research Organization:
- Lawrence Berkeley Lab., CA (USA)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 5553830
- Report Number(s):
- LBL-24404; ON: DE88005742
- Resource Relation:
- Other Information: Thesis (Ph.D.). Portions of this document are illegible in microfiche products. Thesis
- Country of Publication:
- United States
- Language:
- English
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ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
02 PETROLEUM
HYDROCARBONS
CONVERSION
PLATINUM
CATALYTIC EFFECTS
SORPTIVE PROPERTIES
RHENIUM
BUTANE
CARBON MONOXIDE
CATALYSTS
CHEMICAL BONDS
ETHANE
ETHYLENE
HEXANE
HYDROGEN
HYDROGENATION
ISOMERIZATION
PROPYLENE
SURFACES
ALKANES
ALKENES
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
ELEMENTS
METALS
NONMETALS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
SURFACE PROPERTIES
TRANSITION ELEMENTS
400201* - Chemical & Physicochemical Properties
020400 - Petroleum- Processing