Ultrasonication: a competitive method of intercalation for the preparation of alumina pillared montmorillonite catalyst

Abstract

A Ca 2+–montmorillonite clay has been pillared with aluminium hydroxy polycations using ultrasonic technique. This pillared clay is compared with that obtained by conventional method of pillaring. XRD, FTIR in the framework region and surface area measurements elucidate that ultrasonically achieved pillaring is very homogeneous as compared to conventional technique. The uniform pillaring is responsible for the enhanced thermal and hydrothermal stability. However, the use of ultrasonics does not alter the inherent properties such as acidity of the pillared clays, as indicated by IR spectroscopy of adsorbed pyridine. The catalytic activities in the decomposition of propan-2-ol and cumene further confirms the strong acidity of the pillared clays, obtained either by ultrasonic or conventional techniques. In the time on stream studies for both the reactions, slower deactivation was observed on pillared clay prepared by ultrasonication route. Thus, the pillared clay can be obtained via., ultrasonication method of intercalation within 20 min at ambient temperature, with improved textural properties leading to higher stability of the material, without compromising on acidity or catalytic activity of the pillared clay.