Gas-Phase Beckmann Rearrangement of Cyclohexanone Oxime over B-ZSM-5 Derived Titanosilicalite

Four different ZSM-5 zeolites are tested for the gas-phase Beckmann rearrangement of cyclohexanone oxime (CHO) into lactam. B-ZSM-5 derived titanosilicalite (Ti-ZSM-5) exhibits catalytic performances comparable to hydrothermally synthesized titanosilicalite (TS-1), much better than B-ZSM-5 and Al-ZSM-5. The effect of reaction conditions (solvent, feed space velocity, and water) on the catalytic performance of Ti-ZSM-5 is studied. It is found that a quantitative relationship exists among the feed space velocity, the reaction time, and the CHO constant conversion. Ethanol or methanol as solvent shows higher activity, lactam selectivity, and stability than benzene and n-hexanol. The addition of water to the rearrangement with a maximum amount of 1.0 mole per mole CHO results in the increase of CHO conversion while no meaningful changes in lactam selectivity and stability are observed.