Reactivity in combustion process for expanded graphites: influence of dimensional effect

Thermal stability in combustion reaction for natural graphite, graphene and several expanded graphite phases were studied; the kinetic parameters of the oxidation reaction were calculated for two samples. Natural graphite (crystalline particles $200$ – $300\mu$m) has the maximum stability ($E_1=201\pm2$ kJ/mol, $\lg A_1=7.1\pm0.1$), while multilayer graphene is the most reactive ($E_2=120\pm1$ kJ mol$^{-1}$, $\lg A_2=4.3\pm0.10$). The different sample grain sizes and their different structures result in different thermal stabilities: both in the reaction zones location (i.e. in the topochemical equation forms), and in the kinetic parameters' values.