VAPOR-PHASE BECKMANN REARRANGEMENT USING B-MFI ZEOLITES

The vapour-phase Beckmann rearrangement has been studied using a boron -MFI zeolite. The multitude of papers concerning this reaction state t he maximum yield of epsilon-caprolactam at a temperature of 350 degree s C and ambient pressure. Investigation of different process parameter s showed that decreasing the pressure in addition to reducing the temp erature to 300 degrees C leads to an improvement in caprolactam select ivity. This resulted in a drop in catalyst lifetime. In order to reduc e deactivation, the addition of water to the reaction is useful. Contr ary to former papers, it was shown that the deactivation rate decrease d with a raising amount of added water up to 6 mol water per mol cyclo hexanone oxime. The conversion was slightly increased with no consider able effect on the selectivity. Due to the short catalyst service time , a regeneration of deactivated catalysts is inevitable. Using air or oxygen as a regenerating agent, it is possible to regain complete acti vity and selectivity. Nitrogen can also be used as a regeneration gas, although a slight drop in activity must be accepted. For industrial a pplication, a continuous reaction-regeneration system should be employ ed when using fluidized bed reactors. Therefore, the reaction was stud ied in a fluidized bed reactor of laboratory scale. The yields achieve d in this apparatus were in good agreement with the results obtained i n a fixed bed reactor.