Surface properties and porosities of silica and acid-treated montmorillonite catalyst supports: influence on activities of supported ZnCl2 alkylation catalysts

Abstract

A series of progressively acid-treated montmorillonite clays and a range of porous silicas are tested for their effectiveness as supports for ZnCl₂ alkylation catalysts. Support materials are characterised in terms of surface areas, pore volumes and pore size distributions, in an attempt to identify surface properties important in conferring catalytic activity to supported ZnCl₂. The highest catalytic activities are associated with acid-treated clay and silica supports with significant volumes in pores of diameter 10–12 nm. Supports exhibiting pore diameters below this range produce catalysts of very low activities. The fall in catalytic activity associated with larger pore diameter supports is less dramatic. Suggested mechanisms by which the catalytic activity of ZnCl₂ is enhanced in pores within the critical size range are proposed.