Dispersion and catalytic activity of MoO3on TiO2‐SiO2binary oxide support

Abstract

AbstractThe authors present results of an investigation into the dispersion of MoO3on TiO2‐SiO2composite and its reactivity in transesterification of dimethyl oxalate (DMO) with phenol to produce methyl phenyl oxalate (MPO) and diphenyl oxalate (DPO). They examined the effects of support composition, MoO3content, and reaction time on activities of the transesterification. The results show that MoO3/TiO2‐SiO2is more active and selective than MoO3/TiO2, MoO3/SiO2, and TiO2/SiO2catalysts in the transesterification reaction. The best catalytic performance is obtained over a 12%MoO3/8%TiO2‐SiO2, providing a 71.8% DMO conversion and 59.0%, 40.1% selectivities for MPO and DPO, respectively. Through employing X‐ray diffraction and inductively coupled plasma‐optic emission spectrometry, they show evidence strongly suggesting that improvement of catalytic reactivity over the TiO2‐modified SiO2support can be ascribed to the enhanced metal oxide support interactions and the increased dispersion capacity of MoO3phase. They also present evidence showing that incorporation of TiO2in SiO2can elevate the monolayer dispersion capacity of MoO3on SiO2. Thus, they conclude that increased DPO selectivity from MoO3/TiO2‐SiO2catalysts can be primarily attributed to the improvement of MoO3dispersion and the synergistic effect between amorphous MoO3and amorphous TiO2. © 2008 American Institute of Chemical Engineers AIChE J, 2008