South African Journal of Chemistry
On-line version ISSN 1996-840X
Print version ISSN 0379-4350
PILLAI, Sreejarani K. and GHEEVARGHESE, Omanakutty. Synthesis, characterization and activity of sulphate-modified V2O5/SnO2 catalysts. S.Afr.j.chem. (Online) [online]. 2008, vol.61, pp.37-42. ISSN 1996-840X.
Sulphate-modified V2O5/SnO2 catalysts were prepared by a simple impregnation method and characterized using different physicochemical techniques, such as EDX, BET-SA, XRD, FT-IR, TGA and 51V NMR spectroscopy. A simple, effective and environmentally friendly method for the gas phase conversion of cyclohexanone oxime to E-caprolactam by these modified catalysts is presented. The optimal protocol allows ε-caprolactam to be synthesized in excellent yields. NH3-TPD and cumene conversion reactions were used to determine the acid structural properties of the catalysts. Definite correlation was observed between the concentration of medium strength acid sites or Bronsted sites and the E-caprolactam selectivity. Time-on-stream studies showed fast decline in the activity of the catalyst resulting from the basic nature of the reactant and product molecules.
Keywords : Sulphated V2O5/SnO2 catalysts; acidity; vapour phase Beckmann rearrangement.