C152 Free radicals in methane hydrate

Abstract

Methane hydrate irradiated by γ-rays at 77K was investigated by electron spin resonance (ESR). Methyl radicals and atomic hydrogen were observed at 77K but only methyl radicals remained up to 200K, close to dissociation temperature of methane hydrate under atmospheric pressure. The methyl radicals was decayed in the second order process and dimerized to ethane. Activation energy in this process was estimated as 20.0±1.6kJ/mol for 210-230K and 54.8±5.7kJ/mol for 235-260K. This difference may be a key to understand self-preservation (anomalous preservation) of methane hydrate in 243-268K.