The Mechanism Study on the Catalytic Synthesis of 2,6‐Dimethylphenol from KA‐Oil and Methanol over Magnesium Oxide Catalysts

Catalytic synthesis of 2,6‐dimethylphenol from KA‐oil (a mixture of cyclohexanol and cyclohexanone) and methanol was achieved by using magnesium oxide‐supported chromium oxide catalysts in one step. At higher conversion (> 90%), dimethylphenol was formed in high yield (>60 %). The activity of Cr/MgO catalysts depended on the concentration of chromium. The yield of 2,6‐dimethylphenol was also affected by the composition of the ratio of cyclohexanol to cyclohexanone in KA‐oil. Cyclohexanol and cyclohexanone reacting with methanol under the same conditions indicated that pure cyclohexanol or cyclohexanone is less reactive than their mixture, KA‐oil. The adsorption properties of cyclohexanol and cyclohexanone on the surface of Cr/MgO determined by FT‐IR spectroscopy suggest that cyclohexanone is easily reduced to cyclohexanol by the hydrogen which formed in the reaction, and then further reacted with methanol to form 2,6‐dimethyphenol.