The intrinsic reactivity of carbons to oxygen

Abstract The intrinsic reactivities, that is the reaction rates per unit area of pore surface in the absence of any mass transfer restrictions, for combustion of a wide range of carbons have been calculated from published data. The intrinsic reactivities, corrected to a common oxygen pressure of 101 kPa, were ascertained over the temperature range 580 to 2200 K. The reactivities of ‘non-porous’ carbons (diamond, soot, vitreous carbon and pyrolytic graphite) between 770 and 4000 K were also considered. Porous carbons of various origins show intrinsic reactivities that differ by up to 4 orders of magnitude at a given temperature. However, after high-temperature heat treatment, certain carbons of different origin (e.g. sugar and wood charcoals, nuclear and spectroscopic graphites) show closely similar reactivities when reacted with purified oxygen. The reactivities of the ‘non-porous’ carbons show a temperature dependence similar to the average temperature dependence of the porous carbons, but their reactivity expressed per unit external surface area is generally higher than the median intrinsic value of the porous materials.

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