The owner's manual lists no part #. It only says what I quoted above. Not sure if it's purple or not but when you buy it definitely make sure it matches the color of what's already in your Patriot.
I am sure there's an equivalent aftermarket antifreeze available if you don't want to visit your local Chrysler/Jeep dealer. Just go to Napa or O'Reilly's and they can look it up in their parts database and sell you an aftermarket antifreeze.