Methanol and methane formation over palladium dispersed on the lanthanide rare earth oxides

Journal Article · Sun Nov 01 04:00:00 EST 1987 · J. Catal.; (United States)

DOI:https://doi.org/10.1016/0021-9517(87)90158-8· OSTI ID:5206196

Vannice, M A; Sudhakar, C; Freeman, M

To complete their study of the effect of the rare earth oxide (REO) support on the CO hydrogenation reaction over Pd, this metal was dispersed on the oxides of the late lanthanide elements - Tb through Lu. The Pd surface area was measured before and after kinetic runs at 0.1 MPa (1 atm) and 1.5 MPa with these Pd/REO catalysts. Methanation activation energies were 30.4 +/- 1.1 kcal/mole. The turnover frequency (TOF) at 548 K for methane ranged from 1.2 x 10/sup -3/ to 4.8 x 10/sup -3/ s/sup -1/, which is up to 40 times that on Pd powder. The average activation energy for methanol synthesis was 19.6 +/- 0.8 kcal/mole, and TOFs varied from 1.6 x 10/sup -3/ to 6.1 x 10/sup -3/ s/sup -1/. When these results are combined, the patterns for methanation at 0.1 MPa and CH/sub 3/OH synthesis at 1.5 MPa are established as a function of the position of the REO in the periodic table. There is a clear influence of the support on catalytic properties. No trend occurs between methanation activity and the acidity of the support, but a correlation exists between the CH/sub 4/ TOF and the activation energy for electrical conductivity. The TOF for CH/sub 3/OH synthesis shows a strong correlation with the basicity of the REO, which varies with the lanthanide contraction. This behavior also indicated that the support participates directly in the reaction sequence, and this trend strongly supports a mechanism involving formate species on the REO surface, which are formed most readily on the most basic oxides, such as La/sub 2/O/sub 3/. The possibility of a heterogeneous analog of the Cannizzaro reaction is pointed out, and this route may also influence methanol formation.

• Research Organization: Pennsylvania State Univ., University Park (USA)
• OSTI ID: 5206196
• Journal Information: J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 108:1; ISSN JCTLA
• Country of Publication: United States
• Language: English

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10 SYNTHETIC FUELS
ACTIVATION ENERGY
ALCOHOLS
ALKANES
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYST SUPPORTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTIONS
COMPARATIVE EVALUATIONS
DYSPROSIUM COMPOUNDS
DYSPROSIUM OXIDES
ELEMENTS
ENERGY
ERBIUM COMPOUNDS
ERBIUM OXIDES
HOLMIUM COMPOUNDS
HOLMIUM OXIDES
HYDROCARBONS
HYDROXY COMPOUNDS
LUTETIUM COMPOUNDS
LUTETIUM OXIDES
METALS
METHANATION
METHANE
METHANOL
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PALLADIUM
PLATINUM METALS
RARE EARTH COMPOUNDS
SURFACE AREA
SURFACE PROPERTIES
SYNTHESIS
TERBIUM COMPOUNDS
TERBIUM OXIDES
THULIUM COMPOUNDS
THULIUM OXIDES
TRANSITION ELEMENTS
YTTERBIUM COMPOUNDS
YTTERBIUM OXIDES