Ln₂O₃/K₂S₂O₈ Promoted Synthesis of Acetic Acid from Methane and Carbon Monoxide under Mild Conditions

Abstract

The combination of lanthanoid compounds and potassium peroxodisulfate (K₂S₂O₈) has been found to promote the direct formation of acetic acid from methane (40atm) and carbon monoxide (20atm) in trifluoroacetic acid (TFA) at 80°C. The yield of acetic acid was affected strongly by the ligands present with the lanthanoid elements. The ytterbium oxide exhibited higher reactivity than ytterbium sulfide, ytterbium chloride and ytterbium acetate. The sulfide ligand strongly prohibited the formation of acetic acid from carboxylation of methane in TFA. The order of ligands by which acetic acid is formed is oxide>acetate>chloride>sulfide. Of the oxides tested, Yb₂O₃ and Eu₂O₃ showed higher activities.