I would err on the side of no you can't, Facebook are strict on protecting their brand and property. Why take the risk? https://www.facebookbrand.com/dos-donts
But why in the first place do you need to copy smileys and emotions from Facebook when there are so many of them available for free??
...and they don't even look that great to begin with. If you're gonna rip something off make sure you are ripping quality (and have a great legal team too)
I think that your specific question has been answered more than adequately. Going forward, here is what you should ask yourself whenever you have this type of question: "If I spent time and money and effort creating something, how would I feel if someone else just started using it as if it were their own without compensating me?" The answer should be your guide when considering using others' works without permission.