Correlation between surface properties and catalytic activity of clay catalysts

Surface properties always have a strong bearing on catalytic activity. Modification using mineral acids results in the variation of properties like acidity, cation exchange capacity, surface area and porosity of a clay mineral. The present investigation involves the preparation, chemical characterization and surface property evaluation of a set of catalysts, prepared by the acid activation of bentonitic clay collected from Kutch district of Gujarat, India. Chemical characterization was carried out by conventional chemical analysis, physical characterization by XRD, FTIR and DTA and surface property evaluation by surface area, acidity and cation exchange capacity measurements. Activity of the catalysts was monitored by the test reaction, benzylation of benzene. It was found that there is very good correlation among catalytic activity, acidity and cation exchange capacity. The catalyst having the maximum cation exchange capacity showed the maximum conversion in the test reaction. Correlation between iron content and catalyst performance has also been examined. The results obtained in the benzylation of substituted benzenes and polycyclic hydrocarbons are presented. The performance of the catalysts has been compared with the commercial catalysts, K 10 and KSF/0.