Influence of nature of support on the catalytic activity of supported molybdenum-oxo species in benzyl alcohol conversion

Supported catalysts containing 15 wt.% of molybdenum have been prepared by the incipient wetness impregnation method. CaO, MgO, Al2O3, Zr(OH)4 and Al(OH)3 have been used as supports for the preparation of supported Mo catalysts. Characterisation of all the materials prepared has been carried out through BET surface area measurement, X-ray diffractometry and FT-IR spectroscopy. Catalytic activity measurements have been carried out with reference to structure-sensitive benzyl alcohol conversion in the liquid phase. The percentage conversion of benzyl alcohol to benzaldehyde and toluene varied over a large range depending on the support used for the preparation of catalysts, indicating the importance of the support on catalytic activity of Mo catalysts. Al(OH)3 has been found to be the best support for molybdenum among all the supports used. Support–metal interaction (SMI) has been found to play an important role in determining the catalytic activity of supported catalysts.

By incorporating 15 wt.% Mo from ammonium molybdate into aluminum hydroxide, alumina and zirconium hydroxide supports the activity towards disproportionation reaction of benzyl alcohol increases. Disproportionation of benzyl alcohol takes place on strong acid sites giving benzadehyde and toluene.Figure optionsDownload as PowerPoint slideDehydration of benzyl alcohol results on weak acid sites giving dibenzyl ether. The dehydration activity of aluminum hydroxide and alumina supports decreased by the incorporation of 15 wt.% Mo.