Abstract
Propane-deasphalted asphalt (PDA) dissolved in 1, 1, 2-trichloroethane was sulfonated with 25wt.%-and 60wt.%-oleum or sulfuric anhydride to investigate the influence of the kind of sulfonation reagents and its amount, the amount of solvent and reaction temperature and period on the yield and characteristics of char.
Granulated char was obtained with good yield after the sulfonation of PDA dissolved in solvent using both oleum. The yield of char was higher in case of using 60wt.% oleum than 25wt.% oleum, and the required amount of 60wt.% oleum was only 3 times by weight to PDA.
PDA dissolved in solvent was sulfonated with sulfuric anhydride according to the result that the char was obtained with higher yield when the content of SO3 dissolved in sulfonation reagent was higher.
However, the yield of char in this case was lower than in case of using 60wt.% oleum and it was difficult to obtain granulated char.
The contribution of sulfonic groups to the total ion exchange capacity of char was about equal with that of carboxyl-or hydroxyl-groups in case of using 60wt.% oleum. On the other hand, the contribution of the former was extremely larger than that of the latter in case of using sulfuric anhydride. Therefore it was seen that the sulfonation reaction proceeded more vigorously than the oxidation reaction in case of using sulfuric anhydride.
