ACIDIC FERRIERITE TYPE ZEOLITE .1. PHYSICOCHEMICAL AND CATALYTIC PROPERTIES

Ferrierite samples with two aluminum contents (silicon:aluminum equals 15. 4 and 7. 8) were synthesized and acidified through NH//4** plus exchange. One sample was pure ferrierite whereas the second was a mixed ferrierite plus mordenite phase. Because of its small pore channel structure the ferrierite exhibits striking shape selectivity properties for n-hexane cracking and methanol conversion reactions. Acidic properties, as evidenced by infrared and microcalorimetry techniques, of ammonia adsorption correspond to strong acidity. The intimate presence of mordenite in one sample results in severe limitation of the adsorption and diffusion properties and subsequently to higher shape selectivity and also to fast deactivation versus time-on-stream. This is interpreted in terms of intergrowths of ferrierite and mordenite phases.