ACIDIC FERRIERITE TYPE ZEOLITE .2. STEAMED AND ACID LEACHED TREATMENT

Ferrierite type zeolite was thermally treated under steam at temperatures ranging from 870 to 970 K followed by acid leaching with hydrochloric acid solution at 360 K. It was observed that framework aluminum was extracted from the lattice but remained within the pores and channels. A decrease in the number but not the strength of acidic sites followed with a subsequent decrease of catalytic activity and of lifetime on stream. The changes in sorptive properties (diffusivity, capacity) were rather minor for n-hexane and 3-methylpentane adsorbates but very important for toluene. The steamed materials appeared to present no additional interest as acid type catalysts but to be more effective for aromatics diffusion, i. e. as separating columns or adsorbents.