ZEOLITE-CATALYZED RING-SHIFT ISOMERIZATION OF SYM-OCTAHYDROPHENANTHRENE AND CONFORMATIONAL ISOMERIZATION OF CIS-DECAHYDRONAPHTHALENE

This paper reports on two zeolite-catalyzed isomerization reactions of polycyclic hydrocarbons. The first is the transformation of 1,2,3,4,5,6,7,8-octahydrophenanthrene (sym-OHP) to 1,2,3,4,5,6,7,8-octahydroanthracene (sym-OHAn), which we call ring-shift isomerization. Among the Y zeolites and mordenites tested, a proton-form mordenite (HML8) with relatively lower SiO2/Al2O3 ratio afforded a higher yield of sym-OHAn with a higher sym-OHAn/sym-OHP ratio. The best selectivities towards sym-OHAn with HML8 at 250-degrees-C are 89-91% at 58-59% conversion of sym-OHP in decalin and in mesitylene solvents. The second is the conversion of cis-decahydronaphthalene (cis-DeHN) to trans-DeHN, which may be called conformational isomerization. For this reaction, a La ion-exchanged Y zeolite (LaHY) displayed the best selectivity with a trans-DeHN/cis-DeHN ratio of over 10 at 250-degrees-C.