Temperature effect on the removal of hydroxyl radicals by a polycrystalline platinum surface

1983 ◽  
Vol 87 (11) ◽  
pp. 1906-1910 ◽  
Author(s):  
G. T. Fujimoto ◽  
G. S. Selwyn ◽  
J. T. Keiser ◽  
M. C. Lin
Keyword(s):  
Temperature Effect ◽  
Hydroxyl Radicals ◽  
Platinum Surface ◽  
Polycrystalline Platinum

The Adsorption, Desorption, and Exchange Reactions of Oxygen, Hydrogen, and Water on Platinum Surfaces. II. Hydrogen Adsorption, Exchange, and Equilibration

1975 ◽  
Vol 53 (2) ◽  
pp. 298-306 ◽  
Author(s):  
Y. K. Peng ◽  
P. T. Dawson
Keyword(s):  
Hydrogen Adsorption ◽  
Surface Composition ◽  
Co Adsorption ◽  
Exchange Reactions ◽  
Platinum Surface ◽  
Polycrystalline Platinum ◽  
Platinum Surfaces ◽  
Exponential Factors ◽  
Apparent Activation Energies ◽  
Adsorption Desorption

The adsorption, desorption, exchange, and equilibration reactions of hydrogen and deuterium on a platinum filament have been investigated by thermal desorption mass spectrometry. A surface saturated with hydrogen at 120 °K has a coverage 4.2 × 1014 molecules cm−2 and gives desorption spectra with four distinct peaks: β1,(165 °K), β2(220 °K), β3(280 °K), and β4(350 °K). Apparent activation energies and pre-exponential factors were determined for the β2-, β3-, and β4-peaks. For both co-adsorption and sequential adsorption of H2 and D2 the mass 2, 3, and 4 desorption spectra have identical shapes and the gas desorbs at equilibrium throughout. It is concluded that hydrogen adsorbs dissociatively. Exchange and equilibration were studied at 120, 210, and 285 °K by determining the surface composition and isotope distribution after varying fractions of preadsorbed H had been replaced. Following exchange at 120 °K the desorption spectra show a higher D content and a lack of equilibrium in the desorbing gas at low temperature. In most other experiments the mass 2,3, and 4 desorption spectra had identical shapes and the gas desorbed at equilibrium. The results are interpreted by a model which requires that the polycrystalline platinum surface is intrinsically heterogeneous. It appears that different mechanisms are unnecessary to interpret the differences in kinetics observed for exchange and equilibration at low temperatures.

Flame photometric studies of reactions induced by nitric oxide in hydrogen-oxygen—nitrogen flames

1964 ◽  
Vol 277 (1369) ◽  
pp. 143-154 ◽  
Keyword(s):  
Nitric Oxide ◽  
Temperature Effect ◽  
Hydroxyl Radicals ◽  
Atmospheric Pressure ◽  
Atomic Hydrogen ◽  
Homogeneous Catalyst ◽  
Significant Temperature

It has been found that nitric oxide is an effective homogeneous catalyst for the recombination of atomic hydrogen and hydroxyl radicals in fuel-rich flames of hydrogen, oxygen and nitrogen at atmospheric pressure. The results are consistent with the mechanism H + NO + M ⇌ HNO + M , HNO + H → H 2 + NO ( k 4 ), HNO + HO → H 2 O + NO or H 2 + NO 2 ( k 5 ), and the following values for k 4 and k 5 are obtained: k 4 = (1·0 ± 0·5) x 10 -11 cm 3 molecule -1 s -1 , k 5 = (1·5 ±0·5) x 10 -10 cm 3 molecule -1 s -1 , with no significant temperature effect from 1600 to 2000 °K. Alternative mechanisms are discussed.

Lead deposition onto a polycrystalline platinum surface

1981 ◽  
Vol 105 (1) ◽  
pp. A129 ◽  
Author(s):  
G. Praline ◽  
N. Pacia ◽  
J.J. Ehrhardt ◽  
A. Cassuto ◽  
J.P. Langeron
Keyword(s):  
Platinum Surface ◽  
Polycrystalline Platinum

Energetics for the desorption of hydroxyl radicals from a platinum surface

1993 ◽  
Vol 97 (11) ◽  
pp. 2505-2506 ◽  
Author(s):  
Charles E. Mooney ◽  
Louis C. Anderson ◽  
Jack H. Lunsford
Keyword(s):  
Hydroxyl Radicals ◽  
Platinum Surface
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