Methanol adsorption and decomposition on rhodium

Journal Article · Sun Oct 01 00:00:00 EDT 1989 · Journal of Catalysis; (USA)

DOI:https://doi.org/10.1016/0021-9517(89)90164-4· OSTI ID:6844623

Chuah, G K; Kruse, N; Schmidt, W A; Block, J H; Abend, G ^[1]

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1. Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin (Germany, F.R.)

The decomposition of methanol on rhodium probed from {approximately}200 atomic sites of the (001) or (111) planes or Rh field emitter crystals but randomly with regard to crystallographic zones was studied by pulsed field desorption mass spectrometry. High electric field pulses were used to quantitatively desorb the final products, carbon monoxide and hydrogen, thus achieving steady-state conditions. Substantial amounts of methoxy (mainly desorbed as CH{sub 3}{sup +} ions) were also present at the surface. Applying a steady electric field, F{sub R} {ge} 4 V/nm, between the field pulses, led to a deceleration of the decomposition reaction and to increase of the amount of adsorbed CH{sub 3}O and CH{sub 2}O species. There were indicators that the rate-determining step of the reaction is C-H bond cleavage in adsorbed methoxy to form the CH{sub 2}O intermediate. This was supported by the observation of a kinetic isotope effect in the formation of CD{sub 2}O and CHDO from methyl-d{sub 2}-alcohol, CHD{sub 2}OH. Here, the C-H bond breaking to form the CD{sub 2}O was found to be twice as fast as the breaking of the C-D bond which results in CHDO. Field ion microscopy was applied to investigate the influence of the reaction on the structure of the whole hemispherical single crystal surface. There were neither topographic changes nor corrosion of the Rh surface after field-free exposure to 2 Pa methanol at temperatures up to 423 K.

• OSTI ID: 6844623
• Journal Information: Journal of Catalysis; (USA), Journal Name: Journal of Catalysis; (USA) Vol. 119:2; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

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ADSORPTION
ALCOHOLS
CARBON COMPOUNDS
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CARBON OXIDES
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METHANOL
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STABLE ISOTOPES
SURFACE PROPERTIES
SYNTHESIS
SYNTHESIS GAS
TRANSITION ELEMENTS