CHARACTERISTICS OF ALKALI-EXCHANGED Y-ZEOLITES, MONTMORILLONITE, AND AL-PILLARED MONTMORILLONITE, STUDIED BY PHYSICAL AND CHEMICAL METHODS

Microporous catalytic materials with various surface acidities have be en prepared and characterized with instrumental methods as well as che mical reactions. The catalysts were LiY, NaY, KY, CsY, RbY, Na-montmor illonite (Na-mor), and Al-pillared montmorillonite (Al-PILC). Structur al characterization involved atomic absorption and X-ray fluorescence spectroscopies, X-ray diffractometry, infrared spectroscopy in the reg ion of framework vibrations, and thermogravimetric and BET measurement s. Infrared spectroscopy of adsorbed pyridine and the acid-catalyzed i somerization of cyclopropane was used for testing surface acidity. The instrumental methods suggested a decreasing acidity order with increa sing cationic radii, while the chemical reaction showed that the acidi ty decreased in the Al-PILC>LiY>NaY>CsY>KY approximate to RbY sequence . On the first two catalysts oligomerization followed isomerization, a nd the activity of isomerization decreased in the above order.