NOVEL SHIP-IN-THE-BOTTLE TYPE CATALYST - EVIDENCE FOR ENCAPSULATION OF 12-TUNGSTOPHOSPHORIC ACID IN THE SUPERCAGE OF SYNTHETIC FAUJASITE

A new type of ''ship-in-the-bottle'' catalyst has been obtained by enc apsulation of heteropolyacid H3PW12O40 in the supercage of faujasite. As shown by XRD and IR, the structure of zeolite Y after encapsulation is retained. P-31 MAS NMR reveals that the signal at -14.4 ppm, assig ned to the Keggin unit, is in the case of the encapsulated catalyst mu ch broader than the line observed for a sample containing the heteropo lyacid adsorbed on the zeolite. The broadening is due to interaction b etween phosphorus and aluminium from zeolite. Highly active catalysts are formed by encapsulation, as exemplified here by strongly increased activity and modified selectivity in isomerization and disproportiona tion of m-xylene.