PREPARATION AND CHARACTERIZAT ION OF T I-P ILLARED ACID-ACT IVATED CLAY CATALYSTS

catalytic results show that these materials possess remarkably enhanced abilities to catalyse the dehydration of pentanol compared with their AI counterparts (in excess of 200 % in the case of the PILCs and up to 82 % for the PAACs). These activities approach those previously reported for non-pillared acid-activated clays. Polycationic metal 'pillars ' can be intercalated into the interlayer regions of smectite clays to produce thermally stable, porous materials known as pillared clays (Vaughan et al., 1979). Alumina-pillared clays (designated AI PILCs) have generated much interest as shape selective, high-temperature catalysts and adsorbents (Figueras, 1988). It has been shown that acid activation of a clay matrix prior to the intercalation of alumina pillars also results in a thermally stable, porous product (Bovey et al., 1995). These alumina-pillared acid-activated clays (designated A1 PAACs) have been compared with conventional A1 PILCs (Mokaya et al., 1991; Bovey & Jones, 1995), and were found to exhibit increased catalytic activity for butanol dehydration, conversion of cumene and the dehydration of pentanol (Bovey & Jones, 1995; Mokaya & Jones, 1994, 1995). They also showed improved adsorptive properties for the removal of chlorophyll from edible oils (Mokaya et al., 1993). Conventional Ti-pillared clays have been shown to possess large interlayer spacings, high surface areas and good thermal stability (e.g. Baks