Any entitlement to a private pension would have been addressed as part of the divorce proceedings. There would have been a pension adjustment order issued at the time. Even if you weren't entitled to anything, you would have gotten a nil PAO - you get 0.0001% of 1 days benefit i.e. €0
If you are referring to the State pension, I remember reading somewhere that the divorced spouse may be entitled to a benefit (over a cohabiting spouse who gets nothing). Best to ring up welfare in this case.