Synthesis, characterization and catalytic activity studies on cordierite honeycomb coated with ZrO2 based solid super acids

Cordierite honeycomb coated with solid acids such as ZrO2, Mo/ZrO2 and W/ZrO2 were synthesized. These solid acid catalysts were also synthesized in their powder forms. The catalytic materials were characterized for their physicochemical properties such as surface area, surface acidity, crystallinity and morphology by using techniques such as BET, NH3-TPD/n-butylamine back titration, powder XRD and SEM respectively. The catalytic activity of these catalytic materials was determined in an acid catalyzed transesterification reaction of methyl salicylate with phenol to synthesize phenyl salicylate (salol). The effect of concentration of Mo or W ions on ZrO2, nature of the catalyst (whether honeycomb coated or powder form), reaction temperature, reaction time and reusability of the catalytic material in transesterification was studied. Formation of diphenyl ether as a by-product was observed on increasing the concentration of Mo or W ions on ZrO2 and also at higher reaction temperature. The catalytic activity of catalytic materials was correlated with surface acidity and the crystalline phases of catalytic material. Transesterification reactions were also carried out with methyl salicylate and benzyl alcohol or cyclohexanol to synthesize their respective salicylate esters. A probable mechanism of transesterification of methyl salicylate with an alcohol is also proposed. The honeycomb catalysts were found to be efficient, ecofriendly, economical and reusable catalysts compared to their powder forms.