Heterogeneous reactions of H and O2 with solid alkanes
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The paper describes a new source of surface organic radicals whose special feature is a low rate of the initiation of alkyl radicals in reactions of H atoms with the surface of alkanes. A special reactor design was used to accumulate radicals at room temperature and observe alkoxyl radicals RO by the EPR method. For this purpose, alkanes were deposited on aerosil and placed into an EPR cavity. Thanks to the large area of aerosil loads (∼103 cm2), we were able to obtain a stable signal corresponding to a ∼1017 total amount of alkoxyl radicals (the degree of surface coverage ∼0.1%). When O2 was introduced into the reactor in concentrations of 1015–1016 cm−3, a sharp decrease in the signal from surface organic radicals was observed. The process was described as the first-order (RO) s + O2 → HO2 + ketone reaction with a 1.7 × 10−17 cm3 s−1 rate constant.
KeywordsAlkane Aerosil Microwave Discharge Alkoxyl Radical Cyclic Hydrocarbon
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