Understanding the surface and structural characteristics of tungsten oxide supported on tin oxide catalysts for the conversion of glycerol
Résumé
Catalysts with varying WO3 content on SnO2 were prepared and characterized by X-ray diffraction, in situ Raman spectroscopy, X-ray photoelectron spectroscopy and temperature programmed desorption of NH3. In situ Raman analysis reveals the presence isolated monomers and polymeric species of WO3. These catalysts were evaluated for the conversion of glycerol into value added chemicals. Etherification of glycerol with tertiary butanol and preparation of glycerol carbonate from glycerol and urea are studied over these catalysts. The catalytic activity results suggest that the glycerol conversion and selectivity depends on the morphology of WO3 which in turn is related to its content in the catalyst. The catalysts with 5 wt.% of WO3 on SnO2 resulted in high dispersion with larger number of strong acidic sites. The selectivity in the glycerol etherification is related to the nature of the catalyst and reaction time. These catalysts also exhibited high activity for synthesis of glycerol carbonate. The effect of various reaction parameters was studied to optimize the reaction conditions. The catalysts also exhibited consistent activity upon reuse.