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

Abstract

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 µm) has the maximum stability (E 1 = 201 ± 2 kJ/mol, lg A 1 = 7.1 ± 0.1), while multilayer graphene is the most reactive (E 2 = 120 ± 1 kJ mol −1 , lg A 2 = 4.3 ± 0.10). 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.

Characterization of Carbon/Carbon Composites by Kinetic Deconvolution Analysis for a Thermal Oxidation Process: An Examination Using a Series of Mechanical Pencil Leads

“…Thermal oxidation of carbon materials is a class of complex heterogeneous processes in solid–gas systems. Even the thermal oxidation of graphite, which is well-defined in view of crystallography and morphology, is not necessarily a simple single-step reaction. − The reaction process is controlled by the mass-transfer phenomena of the reactant and product gases, that is, O 2 and CO 2 , respectively, in the geometrical constraint of reactant solid–gas contact and diffusional removal of product gas . In addition, the heat-transfer phenomena that originated from the great exothermic effect of the reaction make it challenging to collect reliable data for kinetic calculations .…”