Laser Raman studies of the preparation of platinum and iridium catalyst systems

Journal Article · Thu Sep 01 00:00:00 EDT 1988 · Journal of Catalysis; (USA)

DOI:https://doi.org/10.1016/0021-9517(88)90245-X· OSTI ID:6547751

Chan, S C; Fung, S C; Sinfelt, J H ^[1]

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

Steps in the preparation of Pt, Ir, and Pt-Ir on alumina catalysts have been followed by laser Raman spectroscopy. The samples investigated were prepared by impregnation of alumina with appropriate chloroplatinic acid and chloroiridic acid solutions. The resulting materials were then heated in air at varying temperatures. Laser Raman spectra indicated significant differences in the nature of the surface species remaining when Pt/Al{sub 2}O{sub 3} and Ir/Al{sub 2}O{sub 3} preparations were subjected to such thermal treatments. After a drying step at 110{degree}C, the Pt/Al{sub 2}O{sub 3} preparation exhibits Raman bands at frequencies very close to those at which bands have been reported for the PtCl{sub 6}{sup 2{minus}} ion, whereas the Ir/Al{sub 2}O{sub 3} preparation yields a spectrum significantly different from that reported for the IrCl{sub 6}{sup 2{minus}} ion. With increasing temperature, both the platinum and the iridium species decompose with loss of chlorine ligands. After being heated in air at 500{degree}C, the Ir/Al{sub 2}O{sub 3} sample exhibits a Raman spectrum characteristic of crystalline IrO{sub 2}. The presence of platinum in the bimetallic Pt-Ir/Al{sub 2}O{sub 3} sample inhibits the formation of crystalline IrO{sub 2} to some degree.

• OSTI ID: 6547751
• Journal Information: Journal of Catalysis; (USA), Journal Name: Journal of Catalysis; (USA) Vol. 113:1; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
BIMETALS
CATALYST SUPPORTS
CATALYSTS
CHALCOGENIDES
CHEMICAL PREPARATION
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
CRYSTAL STRUCTURE
DECOMPOSITION
ELEMENTS
HALIDES
HALOGEN COMPOUNDS
HEAT TREATMENTS
IMPREGNATION
IRIDIUM
IRIDIUM CHLORIDES
IRIDIUM COMPOUNDS
IRIDIUM OXIDES
LASER SPECTROSCOPY
LASERS
METALS
OXIDES
OXYGEN COMPOUNDS
PETROLEUM PRODUCTS
PLATINUM
PLATINUM CHLORIDES
PLATINUM COMPOUNDS
PLATINUM METALS
RAMAN SPECTROSCOPY
REACTION INTERMEDIATES
REFRACTORY METAL COMPOUNDS
SPECTROSCOPY
SURFACE PROPERTIES
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS