Yes, there are deterrents that can help.  First, make sure you have a
scratching post somewhere so that the cats don't feel so attracted to your
rug.  Cats don't like citrus smells so really probably anthing orange
scented spray would work.  I tried a cat deterrent spray once and my cat
actually didn't seem to mind it.  But yes, you can use a spray.  I'd go for
something like an orange scent.  Also, try to discourage playing with the
rug when you are home.  While I have given up on some things she does that
may annoy me but aren't harmful to anything, I usually remove her from the
place (like her recent new habit of chewing on electrical cords) and give
her a firm no.  I do that a few times and then call her away from the thing
and reward her with lots of loving when she comes away.  Do that combo and
your rug may be saved!

The best way is to get them something they like to scratch
better than the rug! (There are also sprays available at
Petsmart, etc.) This got my cats to stop scratching my'
furniture and rugs:

http://www.thecatconnection.com/page/TCC/PROD/PLAY-SRTCH/PLAY-0176

You rub it with catnip.