ACIDITY
BECKMANN REARRANGEMENT
BORIA LOADING
BORON OXIDE
CAPROLACTAM
CATALYST CHARACTERIZATION (BET, TPD, XRD)
CYCLOHEXANONE
SELECTIVITY (CAPROLACTAM)
PHASE BECKMANN REARRANGEMENT
VAPOR DECOMPOSITION METHOD
Boron oxide catalysts supported on alumina have been prepared with boria loadings in the range 0-20 wt.-%. These materials were characterized by B.E.T. surface area measurements, X-ray diffraction and temperature-programmed desorption of ammonia and were used as catalysts for the Beckmann rearrangement of cyclohexanone oxime to caprolactam by passing the oxime vapour through a reactor containing the catalysts at 300-degrees-C. The surface areas of the samples decreased as the boria loading was increased, and all catalysts tested for the rearrangement reaction diminished in activity with time-on-stream. There was a direct relationship between the amount of coke which formed on the surface and the loss in catalytic activity. This loss was least for the highest boron oxide loading tested, and this catalyst also featured the least amount of coke formation. Selectivity to caprolactam was associated with the presence of surface acidic sites of intermediate strength. A correlation was observed between the concentration of these surface sites and the selectivity to caprolactam.