Characteristics of Alkali-Exchanged Y Zeolites, Montmorillonite, and Al-Pillared Montmorillonite, Studied by Physical and Chemical Methods

Article abstract of DOI:10.1246/bcsj.69.1429

Microporous catalytic materials with various surface acidities have been prepared and characterized with instrumental methods as well as chemical reactions. The catalysts were LiY, NaY, KY, CsY, RbY, Na-montmorillonite (Na-mor), and Al-pillared montmorillonite (Al-PILC). Structural characterization involved atomic absorption and X-ray fluorescence spectroscopies, X-ray diffractometry, infrared spectroscopy in the region of framework vibrations, and thermogravimetric and BET measurements. Infrared spectroscopy of adsorbed pyridine and the acid-catalyzed isomerization of cyclopropane was used for testing surface acidity. The instrumental methods suggested a decreasing acidity order with increasing cationic radii, while the chemical reaction showed that the acidity decreased in the Al-PILC>LiY>NaY>CsY>KY≈RbY sequence. On the first two catalysts oligomerization followed isomerization, and the activity of isomerization decreased in the above order.