Kinetics of oxidation of α- and β- resin extracts from coal tar pitch

Abstract

The reactions with oxygen at temperatures up to 798 K of α- and β-pitch resins obtained by solvolytic fractionation of a British Coal Tar Pitch were studied thermogravimetrically. It has been shown by previous workers on carbonaceous materials that for each O atom chemisorbed one labile C atom is removed from the surface and the kinetics of oxidation are here shown to follow the relation, dξ/dt= 2Alrδ, where l and r are the mean pore length and radius respectively derived from vapour adsorption studies, δ is the linear rate of regression of the carbon surface on oxidation and A is a constant. Values of 165.3 and 122.6 kJ mol^–1 were found for E for α- and β-resins respectively, the ratio of the available active surface (ASA) being ψα≈ 10³ψβ, and the total available surface being constant at constant degree of oxidation for both resins studied at degrees of oxidation in the range 0.37–0.85.