Structure sensitivity of methane oxidation over platinum and palladium

Journal Article · Sun Apr 01 04:00:00 EDT 1990 · Journal of Catalysis; (USA)

DOI:https://doi.org/10.1016/0021-9517(90)90282-O· OSTI ID:6217495

Hicks, R F; Qi, Haihua; Young, M L; Lee, R G ^[1]

---

1. Univ. of California, Los Angeles (USA)

A series of supported platinum and palladium catalysts were tested for methane oxidation at 260 to 370{degree}C, 50 Torr methane, 110 Torr oxygen, 900 Torr helium, and conversions below 2%. The intrinsic rate varies by more than 5,000 from the least active to the most active catalyst, indicating that the reaction is structure sensitive. The catalytic activity of platinum depends on the distribution of the metal between a dispersed and a crystalline phase. These two phases are distinguished by absorbances at 2,068 and 2,080 cm{sup {minus}1}, respectively, in the infrared spectrum of adsorbed carbon monoxide. The catalytic activity of palladium depends on the metal particle size. For the difference classes of catalysts, the mean steady state turnover frequency (TOF) at 335{degree}C and the mean apparent activation energy (E{sub a}) are as follows: dispersed phase of platinum, TOF = 0.005 s{sup {minus}1} and E{sub a} = 36 kcal/mole; crystalline phase of platinum, TOF = 0.08 s{sup {minus}1} and E{sub a} = 28 kcal/mole; small particles of palladium, TOF = 0.02 s{sup {minus}1} and E{sub a} = 27 kcal/mole; and large particles of palladium, TOF = 1.3 s{sup {minus}1} and E{sub a} = 29 kcal/mole. The structure sensitivity may be explained by differences in the reactivity of the adsorbed oxygen on these metal surfaces.

• OSTI ID: 6217495
• Journal Information: Journal of Catalysis; (USA), Journal Name: Journal of Catalysis; (USA) Vol. 122:2; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
030300* -- Natural Gas-- Drilling
Production
& Processing
33 ADVANCED PROPULSION SYSTEMS
330704 -- Emission Control-- Hydrocarbons
ACTIVATION ENERGY
ADSORPTION
ALKANES
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYST SUPPORTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COMPARATIVE EVALUATIONS
CRYSTAL STRUCTURE
DISTRIBUTION
ELEMENTS
ENERGY
HYDROCARBONS
INFRARED SPECTRA
KINETICS
METALS
METHANE
MICROSTRUCTURE
NONMETALS
ORGANIC COMPOUNDS
OXIDATION
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PALLADIUM
PARTICLE SIZE
PLATINUM
PLATINUM METALS
REACTION KINETICS
SIZE
SORPTION
SPECTRA
SURFACE PROPERTIES
TRANSITION ELEMENTS