Study on Reaction of Coals and Chromic Anhydride

The Estimation by IR Spectrum

Abstract

In aqueous solution, Nakayama coal reacts easily with chromic anhydride (CrO₃). In comparison with the raw coal, the 1, 100-1, 300cm_-1 IR band of CrO₃ pretreated coal is remarkably diminished. The intensity change arises from the interaction with chromic anhydride and hydroxyl groups in the coal. The magnitude of the decrease correlates well with the amount of reacted chromic anhydride. From a comparison of the IR spectra of products obtained from the reaction of several model compounds with chromic anhydride, the behavior of 1, 100-1, 300cm_-1 IR band was assigned to a change in the C-O stretching vibration in the phenolic hydroxyl groups present in the coal. The method may be applicable as a general method for the determination of phenolic hydroxy groups in coals.