12412-52-1Relevant academic research and scientific papers
Transitions in order and molecularity with temperature in gaseous metal oxidation reactions. The Sb-O2 system
Cosic, Biljana,Fontijn, Arthur
, p. 1521 - 1531 (2000)
Examples of reactions which are termolecular near room temperature and gradually switch over to complex-forming bimolecular reactions with increasing temperature are discussed. The Sb/O2 system, which is known from D. Husain's work to be termolecular at 300 K, has been studied here from 1165-1495 K at 12 to 52 mbar in a high-temperature fast-flow reactor (HTFFR). Sb was vaporized from a crucible and atomic resonance absorption spectrometry was used to measure the rates of Sb consumption. Under these conditions the reaction, identified as Sb + O2 → SbO + O, is pressure-independent with k(T) = 6.3×10-11 exp (-9107 K/T) cm3 molecule-1 s-1. The 2σ precision limits are ±8% and the corresponding estimated accuracy limits are ±24%. The results suggest that Do(Sb-O) = 444±28 kJ mol-1. The results are compared to those of other endothermic metal-atom O2 abstraction reactions, all of which have pre-exponentials on the order of 10-10 cm3 molecule-1 s-1 and activation energies for abstraction close to the endothermicity. This allows assessments of the relative importance of bi-, and ter- molecular kinetics, as illustrated for As + O2. by Oldenbourg Wissenschaftsverlag, Muenchen.
