Preparation of MFI Zeolite Catalyst Supported on Silicalite Foam and Its Catalytic Property in the Cracking of n-Octane

摘要

Foam-type MFI zeolite catalyst was prepared by dispersing fine(-0.2 murn)particles of MFI zeolite on sil-icalite foam.Catalytic cracking of n-octane was investigated over the foam-type catalyst and Delplot method was employed to interpret product compositions for deducing reaction mechanism.The Si/Al molar ratio of dispersed MFI zeolite was estimated 25 and its dispersed amount of silicalite foam was 25 wt%.Since the apparent density of the foam type catalyst was very low 0.11 gcentre dotcm~(-3),the catalyst loading amount could be varied from 0.02 g to 0.5 g without concerning pressure drop,providing a wide variance in the residence time of the reactants and products.The conversion and olefin yield in the catalytic cracking of n-octane increased with the catalyst loading.The product composition was very simple and could be explained by applying the protolytic cracking mechanism when the catalyst loading was small.Higher loading of the catalyst brought about further reactions of cracked products,accumulating lower olefin and paraffin with low reactivity in product stream and resulting in complex product composition.