Physicochemical Properties of Montmorillonite Interlayered with Cationic Oxyaluminum Pillars

Abstract

By ion exchanging expandable clay minerals with large, cationic oxyaluminum polymers, “pillars” were introduced that permanently prop open the clay layers. On the basis of thermal, infrared spectroscopic, adsorption, and X-ray powder diffraction (XRD) analysis, the interlayering of commercial sodium bentonite with aluminum chlorohydroxide, [Al₁₃O₄(OH)₂₄(H₂O)₁₂]⁺⁷, polymers appears to have produced an expanded clay with a surface area of 200–300 m²/g. The pillared product contained both Brönsted and Lewis acid sites. XRD and differential scanning calorimetry measurements indicated that the micropore structure of this interlayered clay is stable to 540°C. Between 540° and 760°C, the pillared clay collapsed with a corresponding decrease in surface area (to 55 m²/g) and catalytic cracking activity for a Kuwait gas oil having a 260°-426°C boiling range.