Pt-Ir/Al sub 2 O sub 3 catalysts-the effect of Pt-Ir interaction on Ir agglomeration and catalytic performance

Journal Article · Sat Jul 01 00:00:00 EDT 1989 · Journal of Catalysis; (USA)

DOI:https://doi.org/10.1016/0021-9517(89)90310-2· OSTI ID:7263245

Huang, Y J; Fung, S C; Gates, W E; McVicker, G B ^[1]

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1. Exxon Research and Engineering Company, Annandale, NJ (USA)

Interaction between Pt and Ir has been found to occur on freshly impregnated Pt-Ir/Al{sub 2}O{sub 3} subjected only to drying at 393 K. Iridium in the freshly prepared bimetallic precursor material retains the same reduction behavior as monometallic Ir. Iridium promotes the reduction of Pt in the bimetallic precursor material. This promotion results in a 20 K lower temperature-programmed reduction peak temperature than that observed for monometallic Pt. The incorporation of Pt into Ir clusters retards the oxidative agglomeration of Ir. Reduction followed by calcination causes a higher degree of Ir oxidative agglomeration than direct calcination at the same temperature. The incorporation of Pt into Ir clusters decreases the cracking activity of the Ir component as well as the coking tendency of the Pt component, and therefore enhances benzene selectivity. The catalytic performance of a Pt-Ir catalyst approached that of a Pt-only catalyst as the degree of Ir agglomeration increases. The cracking of n-hexane molecules takes place more frequently at the terminal carbon atom position as the degree of Ir agglomeration increases.

• OSTI ID: 7263245
• Journal Information: Journal of Catalysis; (USA), Journal Name: Journal of Catalysis; (USA) Vol. 118:1; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020400* -- Petroleum-- Processing
AGGLOMERATION
ALKANES
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
AROMATICS
BENZENE
BIMETALS
CALCINATION
CARBONIZATION
CATALYST SUPPORTS
CATALYTIC CRACKING
CATALYTIC EFFECTS
CATALYTIC REFORMING
CHALCOGENIDES
CHEMICAL REACTIONS
COAL TAR OILS
COHERENT SCATTERING
COKING
CRACKING
DECOMPOSITION
DIFFRACTION
DISTILLATES
ELECTRON MICROSCOPY
ELEMENTS
ENERGY SOURCES
FOSSIL FUELS
FUELS
HEXANE
HYDROCARBONS
IRIDIUM
METALS
MICROSCOPY
NAPHTHA
OILS
ORGANIC COMPOUNDS
OTHER ORGANIC COMPOUNDS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PETROLEUM
PETROLEUM DISTILLATES
PETROLEUM FRACTIONS
PLATINUM
PLATINUM METALS
PYROLYSIS
REDUCTION
REFORMER PROCESSES
SCATTERING
SPECTROSCOPY
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENTS
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY