Heterogeneous reactions of H and O-2 with solid alkanes

摘要

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 (similar to 10(3) stop cm(2) stop), we were able to obtain a stable signal corresponding to a similar to 10(17) stop total amount of alkoxyl radicals (the degree of surface coverage similar to 0.1%). When O-2 was introduced into the reactor in concentrations of 10(15)-10(16) cm(-3) stop, a sharp decrease in the signal from surface organic radicals was observed. The process was described as the first-order (RO)(s) + O-2 -> HO2 + ketone reaction with a 1.7 x 10(-17) cm(3) s(-1) stop rate constant.