CUBIC AND HEXAGONAL FAUJASITES WITH VARYING SI A1 RATIOS .1. SYNTHESIS AND CHARACTERIZATION/

Zeolite faujasite type with hexagonal structure (EMT) and zeolite fauj asite types with cubic structure (FAU) were synthesized with crown eth ers as templating agents. The Si/Al ratio of the as-synthesized sample s was determined to 3.7. The samples were dealuminated by steaming at 773, 873 and 1073 K, respectively. A part of the dealuminated samples was treated with diluted acid to extract the non-framework aluminum. N ature and concentration of the acid centres were estimated by IR spect roscopy and TPDA measurements. From N-2 isotherms follows that the ext racted samples undergo a partial damage of the structure. It seems tha t the EMT samples are more stable in the process of steaming and extra ction with diluted acid.