Selective gas phase oxidation of methanol to formaldehyde over aluminum promoted vanadium phosphate

Vanadium phosphate (VPO) is an interesting catalytic material because of its ability to catalyze reactions, such as partial oxidations with high selectivity. Selective gas phase oxidation of methanol to formaldehyde is achieved over simple aluminum promoted vanadium phosphate (Al-VPO) impregnated heterogeneous catalyst. A series of Al-VPO (3, 5, 10, 15 and 20 wt%) catalysts have been synthesized and the catalytic behavior has been studied by carrying out methanol oxidation. The catalytic oxidation runs revealed a significant effect of the vanadium phosphate giving 100% selectivity to formaldehyde at 200 °C. The conversion can be enhanced to 94% with the sacrifice of the selectivity.

Graphical abstractVanadium phosphate and aluminum promoted vanadium phosphate have been synthesized in a facile technique. The catalysts are found to be robust enough to achieve high degree of methanol oxidation to formaldehyde.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► VOHPO4·0.5H2O as catalyst precursor. ► Aluminum promoted vanadium phosphate showed promising results for methanol oxidation. ► Generation of surface methoxo-vanadium (V) centres by adsorption of gaseous methanol. ► Activated methoxo ligands are oxidized and eliminated as formaldehyde. ► Excellent high yields are obtained with 5 wt% Al-VPO at lower temperature.