CATALYTIC TRANSFORMATIONS OF OLEFINS ON HZSM5 OBSERVED BY RADIOLYSIS EPR

A new method for elucidating elementary reaction steps in zeolite cata lysis was demonstrated for reactions of isobutene and other monoolefin s on HZSM5. Radiolysis was used to ''spin label'' reaction products, a nd EPR was used for product analysis. The evolution of products was re vealed by quenching the reactions cryogenically in a series of equilib ration experiments. Isobutene dimerization and isomerization occur on HZSM5 even at 77 K, and cracking occurs below room temperature. The ra diolysis/EPR results allow a consistent interpretation of the literatu re on EPR signals that arise spontaneously upon interaction of acyclic olefins with air-activated H-Mordenite and HZSM5.