PREPARATION AND CATALYTIC PROPERTIES OF SUPPORTED HETEROPOLYACID SALTS

Heteropoly compounds are receiving increasing interest as environmenta lly compatible solid acid catalysts. Partial Cs+ exchange into 12-tung stophosphoric acid converts the water soluble, low surface area (< 5 m (2) g(-1)) parent acid into submicron water-insoluble Bronsted acids w ith surface areas exceeding 100 m(2) g(-1). The insolubility of the Cs acid salt makes preparation of large particle supported catalysts by conventional impregnation procedures impractical, although application s in packed bed or slurry reactors require millimeter-sized pellets to avoid pressure drop or filtration problems. Here, we report on a new but simple technique that produces an eggwhite distribution of active Cs-acid salt of 12-tungstophosphoric acid within a large silica extrud ate by carrying out a reaction deposition directly inside the extrudat e. We examine these catalysts in aromatic alkylation reactions.