Re-usability of zeolites and modified clays for alkylation of cyclohexanol a contrast study

Abstract

Organic sulfonic acid treatment of montmorillonite results in micro-pores on the surface of modified clays providing access to acid sites in the interlayer. Performance of modified clay catalysts for alkylation of para-cresol with cyclohexanol were compared with microporous zeolites. Phenoldisulfonic acid treated clay catalyst showed maximum activity comparable with that of beta-zeolite. Modified clay- and zeolite-catalysts on reuse for the alkylation exhibited different behaviour. Modified clays showed same activity as in the first cycle while zeolites showed significantly reduced catalytic activities on reuse. Differences in behaviour were further investigated by characterizing the reused samples with TGA, acidity and surface measurements. Used zeolite samples showed considerable variations in acidity, surface characteristics and TGA pattern, which was attributed to the formation of coke. Absence of coke in clays and deposition of coke in zeolites is attributed to difference in their pore architecture.