PRODUCTION OF OXALATE BY THE OXIDATION OF COAL WITH OXYGEN IN A CONCENTRATED SODIUM HYDROXIDE SOLUTION.

Oxidation of coals with oxygen in 25 mol kg** minus **1 sodium hydroxide solution was carried out to examine the effect of rank of coalification on the production of oxalate. Fourteen coal specimens, from bituminous coal to peat, were used. Lower rank coal yielded largely volatile acids comprising mainly acetic acid. Volatile acid yields reached maximum values of 20-24% on carbon base at an early stage of the reaction (10-20% CO//2 yield). Yield ratio (ratio of oxalic acid yield (%)/CO//2 yield (%)) increased from 0. 8 for Goonyella coal to 1. 6 for Tempoku peat with lowering of rank of coalification. When coals were satisfactorily oxidized, the yield of oxalate reached approximately 120 wt% as oxalic acid on dry ash free coal base in spite of the difference of rank of coalification.