Catalysis Letters, Vol.81, No.1-2, 113-117, 2002
Preparation of heterogeneous vanadium (VO2+) catalyst for selective hydroxylation of cyclohexane by molecular oxygen
A vanadium(II) Schiff base ligand, [1,4-bis (salicylidene amino)-phenylene] vanadium oxo complex bonded on carbamate-modified silica gel, has been synthesized. The liquid-phase oxidation reaction of cyclohexane with this catalyst was found to give cyclohexanol at moderate condition (reaction temperature 200 degreesC, pressure 23.8 atm, catalyst concentration 1.0% and 16 h of reaction time) with considerably higher specificity (18:1 ratio with cyclohexanone and negligible acid formation). The catalyst has been tested for 200 h of reaction and the leaching of the metal occurs negligibly.