Laboratory-steamed catalyst fractions

The heavier portion of the fresh and laboratory steamed catalyst (Float B) exhibits a decreased micropore volume with respect to the lighter portion (Float A), suggesting that the density fractionation within each catalyst reflects the presence of a finite range of zeolite crystallinities. Particularly for the fresh catalyst, this inhomogeneity is small (Table VIII). 

The comparison of physical properties of laboratory-steamed catalyst with those of equilibrium catalyst fractions given in Table VII indicates that a wide range of steaming temperatures is necessary to reproduce the equilibrium catalyst deactivation profile for lab steaming times of one day or less. These results indicate that an improved catalyst aging procedure for simulating... 

Comparison with Lab Steam Deactivations. Catalyst fractions which exhibit 50% or greater loss in micropore volume/crystallinity comprise less than 15% of equilibrium catalyst. The major portion of this particular equilibrium catalyst is remarkably similar to the material which results from increasingly severe laboratory steam deactivations at 815°C or less (Tables VI and VII). Dealumination is rapid, the associated crystallinity loss is small, and the matrix surface area shows little change. Crystallinity retention falls below 70% only after dealumination is complete. 

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