Do XT IEC contactors have DC ratings on the contacts?

Yes, the IEC XT series contactors do carry DC ratings on the contacts. The specific ratings for each contactor at different voltages can be found in the online IEC Contactors and Starters catalog, volume 5 tab 1, in the Technical Data section.

http://www.eaton.com/ecm/groups/public/@pub/@electrical/documents/content/vol05_tab01.pdf#page=107

For definitions of the various AC and DC ratings, please see AC and DC Ratings for Low Voltage Control.

For DC wiring requirements, please see DC Wiring for XT Contactors.