| Autor: |
Dietmar Hofer, Friedrich Steinbach |
| Rok vydání: |
1979 |
| Předmět: |
|
| Zdroj: |
Surface Science. 79:311-332 |
| ISSN: |
0039-6028 |
| DOI: |
10.1016/0039-6028(79)90043-8 |
| Popis: |
A new modification of molecular beam relaxation spectrometry (MBRS) of surface processes is described making use of partial modulation in order to study nonlinear processes: a constant particle beam is directed towards the catalyst surface, the surface temperature is modulated due to absorption of a modulated beam of UV light, reaction products are analyzed by use of phase sensitive mass spectrometric detection. The application of the method is shown by a study of catalytic decomposition of methanol on polycrystalline NiO. Formation of CO was found to be a monomolecular, formation of H2 and H2O bimolecular processes. The resulting mechanism may be described as follows: Rate constants in dependence from surface temperature T0 are η = 1.8 × 103exp(−46RTokJmol); kd1 = 1.8 × 1010exp(−92RTl0kJmol) s−1; kd2 = 1.2 × 10−2exp (−88RT0kJmol) cm2 particles−1 s−1; kd3 = 3.5 × 10−4exp(−88RT0kJmol) cm2 particles−1 s−1. Average surface residence times of the intermediates are: 27 ⩾ τHCO \ 1 ms at 550 ⩽ T0 ⩽ 650 K; 42 ⩾ τH ⩾ 7 ms at 540 ⩽T0 ⩽ 610 K; 177 ⩾ τOH ⩾ 19 ms at 550 ⩽ T0 ⩽ 645 K. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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