Can I use 11 speed chainrings with 9 speed chain?
Basically, so long as the front derailleur is wide enough to carry a 9 speed chain that you're using (so a 9 speed front derailleur would work) without problems, you'll be fine. 

So, go for it, provided they'll fit (i.e. the bolt pattern + BCD matches). 

As for mismatching the chainrings, chances are these are the cheapest ones on the market now. My road bike, for example, runs a Shimano 105SC groupset (7 speed) and I'm going to have to replace the chain rings with things that are "10/11 speed" eventually.