Synthesis of tungsten–vanadium mixed oxides for ethanol partial oxidation

Abstract

Vanadium–tungsten mixed oxides with various compositions were synthesized from a mixture of sodium metavanadate and sodium tungstate solution by sol–gel method. For comparison, pure tungsten oxide and pure vanadium oxide were synthesized. X-ray diffraction analyzes and Raman spectroscopy were employed to examine structure after calcination at 600 °C. In the cases of mixed oxides, new peaks were observed from X-ray diffraction analysis, which were not found in either pure tungsten oxide or pure vanadium oxide. X-ray photoelectron spectroscopy was used to determine oxidation states of vanadium and tungsten. The sample compositions were determined by energy dispersive spectroscopy (EDS) and correlated remarkably well to the V:W ratios in solution. Catalytic activities for partial oxidation of ethanol to acetaldehyde were investigated in a fixed-bed reactor and it was found that the catalytic activity was strongly dependent on composition. When small amount of tungsten was added into vanadium oxide, catalytic activity was improved, compared with pure vanadium oxide. Among synthesized samples, 5% WO 3–95% V 2O 5 mixed oxide showed highest catalytic activity.