Effect of Reactor Material and Reaction Conditions on the Formation of Oxalate in the Oxygen-oxidation of Acetate in Alkaline Solutions at Elevated Temperatures -Oxidation of Coals in Liquid Phases. VIII.-

Abstract

The effects of reactor material, coexisting metal and reaction conditions on the oxidation of acetate to oxalate have been studied to clarify the mechanism of oxidation of coal in alkaline solutions and to improve the yield of oxalate. The yield of oxalate was greatly affected by the reactor material and coexisting metal, and the rate of oxidation of oxalate in a Ni reactor was as follows: Cu>Co>Ni>Mn>Cr>Fe. Two reaction mechanisms were considered from the yield ratio of oxalate/CO₂: consecutived oxidation of acetate to CO₂ via oxalate by Fe or Fe₂O₃ and the direct oxidation of acetate to CO₂ by Co and Mn. In the presence of Fe or Fe₂O₃ in a Ni reactor, the yield of oxalate increased remarkably as a result of lowering of the rate of oxidation of oxalate more than that of acetate. In addition, the yield of oxalate greatly increased with an increasing concentration of NaOH since hydroxide ion accelerated the rate of oxidation of acetate, but had little effect on the rate of oxidation of oxalate.