Supercritical processing of functionalized size selective microporous materials

A supercritical fluid silanation process is applied to effectively functionalize commercial microporous materials without blocking the pore channels. In this approach, supercritical carbon dioxide (SCCO2) is used to deposit mercaptopropyl silane into the microporosity of zeolite beta. The thiol group was subsequently oxidized into sulfonic acid. The size selective catalytic properties of the SCCO2 modified zeolite compare well with similar materials prepared by an in situ silanation process reported by Jones et al. The active functional groups were delivered to the internal pore surface of the microporous material and remain accessible to molecules that can enter the pore channels. The supercritical process provides an alternative approach to functionalize microporous materials because of the enhanced diffusivity of the functional molecules in the micropore channels and accelerated reaction kinetics. Furthermore, the supercritical process simplifies the materials preparation and may open up new opportunities for commercial zeolites. (C) 2000 Elsevier Science B.V. All rights reserved.