ALPO4-TIO2 CATALYSTS .5. VAPOR-PHASE BECKMANN REARRANGEMENT OF CYCLOHEXANONE OXIME

Vapor-phase Beckmann rearrangement of cyclohexanone oxime over AlPO4 (AP) and AlPO4-TiO2 (APTi, 25-75 wt%) catalysts was investigated. Apparent rate constants and activation parameters were calculated in terms of the kinetic model of Bassett and Habgood for first order reaction processes. In all cases the selectivity to epsilon-caprolactam (S-epsilon-CAPR) increased with reaction temperature and, furthermore, at the same level of conversion, APTi catalysts exhibited better S-epsilon-CAPR values than AP catalysts. Moreover, although the increase in TiO2 content strongly decreased oxime conversion, the S-epsilon-CAPR continuously increased. From the distribution of reaction products and their selectivity curves, which showed that amide and nitrile were obtained by parallel reactions, an outline of the catalyzed rearrangement was presented.