Carbonization properties of carbonaceous substances oxidized by air blowing-II. Acid-catalyzed modification of oxidized residual oil for better anisotropic development

The catalytic carbonization and modification of oxidized residual oils were studied using AlCl₃. Although the catalyst increased the coke yield in the carbonization, the size of the anisotropic units developed in the resultant coke decreased. Modification at proper temperatures was found effective in restoring the potential of the pitch for the anisotropic development of the flow texture. The modified pitch remained essentially quinoline soluble after the above-mentioned modification with only a minor amount of it becoming insoluble. After the modification, some anisotropic units of small diameter were observable in the quinoline soluble phase after separation of the quinoline insoluble phase. These units were recrystallized into smaller numbers of larger units by the gentle evaporation of the solvent quinoline. The significance of the soluble mesophase was discussed.