Study on the IR spectra of the pillared clay molecular sieve

The surface acidity and hydroxyl vibrations of the pillared clay molecular sieve containing mixed metal complexes were determined by IR spectra. The results suggest that (1) the clay and pillared clays have more Lewis acid sites than Bronsted acid sites; (2) their surface acidity is varied with the pillaring agents and comes from their pillars, which can be transfered into oxides and release protons and produce Bronsted and Lewis acid sites after calcination; (3) the hydroxyl groups (3500-3700 cm^MIN1) are originated mainly from the aluminum located on the octahedral skeleton and their intensities decrease with the increase in temperature; (4) the stability of the pillars in the pillared clays affects their surface hydroxyl groups and Bronsted and Lewis acid sites.