SMSI effects on CO adsorption and hydrogenation on Pt catalysis

Journal Article · Sat Jan 01 04:00:00 EST 1983 · J. Catal.; (United States)

OSTI ID:6264472

Vannice, M A; Twu, C C; Moon, S H

Infrared spectroscopy has been employed to characterize adsorbed CO species under steady-state reaction conditions in the presence of H/sub 2/ and also under equilibrium adsorption conditions in the presence of He. During reaction, kinetic data were obtained simultaneously with ir spectra using a special ir reactor cell. Turnover frequencies on Pt were found to vary more than 100-fold as the support material varied, and the activity ranking of these catalysts was: Pt/TiO/sub 2/ (SMSI) > Pt/TiO/sub 2/ (LT) greater than or equal to Pt/eta-Al/sub 2/O/sub 3/ approx. = Pt/SiO/sub 2/-Al/sub 2/O/sub 3/ > Pt/SiO/sub 2/. Two principal ir bands were observed on Pt - a high-frequency band between 2050 and 2080 cm/sup -1/ and a low-frequency band between 1780 and 1860 cm/sup -1/. Except for TiO/sub 2/-supported Pt, very similar behavior was observed, i.e., intense ir bands occurred which were nearly insensitive to temperature and the presence of H/sub 2/, and these catalysts exhibited strong bands under reaction conditions. In contrast, the Pt/TiO/sub 2/ (SMSI) catalyst showed almost no ir-detectable CO during reaction and, even more surprising, CO band intensities were also markedly reduced at 300 K by the presence of H/sub 2/. No obvious correlation was found between detectable CO species and specific activity; however, this study strongly infers that only a very small fraction of surface Pt atoms constitute active sites, and the higher activity occurring on the SMSI Pt/TiO/sub 2/ catalyst is attributed to a weakened CO-metal bond resulting in more competitive H/sub 2/ chemisorption and higher surface concentrations of hydrogen under reaction conditions.

• Research Organization: Pennsylvania State Univ., University Park
• DOE Contract Number: AC02-77ER04463
• OSTI ID: 6264472
• Journal Information: J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 79:1; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

090121 -- Hydrocarbon Fuels-- Chemical Synthesis-- (1976-1989)
10 SYNTHETIC FUELS
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ADDUCTS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
BINDING ENERGY
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYST SUPPORTS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL PREPARATION
CHEMICAL REACTIONS
CHEMISORPTION
COMPARATIVE EVALUATIONS
ELEMENTS
ENERGY
EQUILIBRIUM
FLUIDS
GASES
HELIUM
HIGH TEMPERATURE
HYDROGEN
INFRARED SPECTRA
METALS
METHANATION
MINERALS
MOLECULAR STRUCTURE
NONMETALS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PLATINUM
PLATINUM METALS
RARE GASES
SEPARATION PROCESSES
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SORPTION
SORPTIVE PROPERTIES
SPECTRA
STEADY-STATE CONDITIONS
SURFACE PROPERTIES
SYNTHESIS
TITANIUM COMPOUNDS
TITANIUM OXIDES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS