Formaldehyde production via partial oxidation of methanol over oxides of Cr, Mo and W supported on ceria-zirconia

Oxides of chromium (Cr), molybdenum (Mo), or tungsten (W) were supported on mixed oxides of cerium and zirconium (CeO₂-ZrO₂) by an incipient wetness impregnation process, and used to investigate their activities for partial oxidation of methanol. High Resolusion Transmission Electron Microscope (HR-TEM) revealed that nanoparticles of Cr₂O₃, MoO₃ or WO₃ were formed on the CeO₂-ZrO₂ support. The particle sizes of Cr₂O₃, MoO₃ and WO₃ were 2-4, 3-6 and 4-5 nm, respectively. As a result of partial oxidation of methanol at 275 – 450 °C, formaldehyde (CH₂O) was obtained as the major product over all these catalysts. Cr₂O₃ supported on CeO₂-ZrO₂ produced both CO and CO₂ along with H₂ production, while MoO₃ and WO₃ on CeO₂-ZrO₂ support generated only CO as a by-product. It was found that MoO₃ supported on CeO₂-ZrO₂ showed the highest methanol conversion and CH₂O yield among these three catalysts. (paper)