Oxidation of CO and hydrocarbons over noble metal catalysts

Journal Article · Tue May 01 04:00:00 EDT 1984 · J. Catal.; (United States)

DOI:https://doi.org/10.1016/0021-9517(84)90178-7· OSTI ID:6715120

Yao, Y F.Y.

The oxidation of CO, C/sub 3/H/sub 6/, 1-hexene, and toluene under excess O/sub 2/ has been studied over precious metal (PM) catalysts, Pt, Pd, and Rh, in the form of unsupported wires or supported on ..gamma..-Al/sub 2/O/sub 3/ or CeO/sub 2//Al/sub 2/O/sub 3/. The kinetics were affected by the state of the metal dispersion, the pretreatment temperature, the reaction conditions, and the presence of CeO/sub 2/. The existence of two types of surface sites each with its own reaction kinetics is postulated to explain the results; to wit: Type I kinetics, exemplified by the PM wires, is first-order with respect to O/sub 2/ and negative first-order with respect to CO over all three metals. Over the same Pt or Pd catalysts, the olefin oxidation is strongly self-inhibited by HC and more than first-order in O/sub 2/, whereas the opposite was found for Rh. These sites are attribted to PM particles in low oxidation state. Type II kinetics is positive order with respect to CO and nearly independent to oxygen partial pressure. The olefin oxidation is less self-inhibiting by HC (for Pt and Pd) and by O/sub 2/ (Rh) than type I. Generally, the activation energies are lower. This type of kinetics prevails over PM surface of higher dispersion and higher oxidation state. The presence of CeO/sub 2/ promotes the type II kinetics. The oxidation of 1-hexene and toluene is very similar to that of C/sub 3/H/sub 6/ and suggests that the adsorption of the hydrocarbon on the surface through the double bond is important.

• Research Organization: Ford Motor Co., Dearborn, MI
• OSTI ID: 6715120
• Journal Information: J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 87:1; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020500* -- Petroleum-- Products & By-Products
ALKENES
ALKYLATED AROMATICS
AROMATICS
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
ELEMENTS
HEXENES
HYDROCARBONS
METALS
ORGANIC COMPOUNDS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PALLADIUM
PLATINUM
PLATINUM METALS
PROPYLENE
RHENIUM
TOLUENE
TRANSITION ELEMENTS