Effect of chemical pretreatment on coal solubilization by methanol-NaOH

Chemical pretreatment including reduction with metallic potassium (K-THF-isopropanol), reductive methylation (K-THF-CH3I), decarboxylation, reduction with LiAlH4 and O-methylation was used to modify the structure of coals. The effect of this pretreatment on solubilization by methanol-NaOH was evaluated. The results indicate that preliminary reduction with potassium enhances the reactivity of coal, whereas preliminary reductive methylation decreases its susceptibility to solubilization. The other three pretreatments, involving elimination, transformation or derivatization of the carboxyl and hydroxyl groups in coal, also have negative effects on solubilization, showing that these groups, apart from participating in the physical effects of disintegration and dissolution of the coal in the reaction medium, greatly affect coal reactivity.