Here is a short video looking at the shape selective properties of the zeolite mordenite for the production of 2,6-Diisopropylnaphthalene (2,6-DIPN) as opposed to 2,7-Diisopropylnaphthalene (2,7-DIPN).
The blue (2,6-DIPN) isomer has a molecular shape which fits the zeolite channel better than the yellow (2,7-DIPN) isomer. The computed energy barriers for the migration of the (2,7-DIPN) isomer are higher than the barriers for the (2,6-DIPN) isomer.
So, once a isomerization has been catalyzed by the zeolite, the (2,6-DIPN) isomer can escape from the zeolite, whereas a (2,7-DIPN) isomer is retained by the catalyst and likely to undergo further isomerization reactions.
Here is a patent on this topic: https://www.google.com/patents/US5017735