Isomerization of dimethylnaphthalenes over zeolites

A dimethylnaphthalene (DMN) isomer mixture from a reforming unit was reacted at 350°C and atmospheric pressure over H-mordenites (Si/Al ranging from 5 to 100), a partially decationated NaY (Si/Al=2.4) and a slightly dealuminated HY (Si/Al=5), with the aim of increasing the 2,6- and 2,7-DMN content by isomerization. The best results were obtained on H-mordenite with Si/Al=10, where shape selective effects made possible to double the amount of the valuable isomers while limiting to a negligible extent the side reactions of disproportionation and dealkylation.