The nature of active sites on zeolites: VII. Relative activities of crystalline and amorphous alumino-silicates

Abstract

The rate constants for o-xylene isomerization over silica-alumina, several faujasite type zeolites and synthetic mordenite have been measured at various temperatures and compared at 260 °C to silica-alumina. The rate constants vary over a range of 40,000. Of the catalysts examined, H-mordenite was the most active and MnX zeolite the least active. Many of the faujasite type catalysts were less active than silica-alumina. The activities of the most active faujasite catalysts were only about forty times the activity of silica-alumina and the differences in activities of the various catalysts can be reasonably interpreted in terms of the Bronsted acid site concentrations. No evidence of superactivity is observed in this reaction.