Can I reduce the size of my chin with liposuction? I assume there is fatty tissue that surround the bone?

It is best to have a consultation to identify your needs and review the aesthetic results that you desire.  Assumption without examination is not good medicine. 

The projection of the chin cannot usually be reduced with liposuction.  The bone is the major factor that produces the projection and there is minimal fat under the skin in front of the chin.  The usual method to reduce the chin projection would be shaving down the chin bone.  

Liposuction can be done to remove excess fat below the chin and improve the jawline. It is not done directly over the front of the chin. 
I recommend seeing a board certified plastic surgeon and discussing what area of your chin you wish to reduce and they can offer options.
Best of luck

Liposuction will not remove enough fat to make a noticeable difference and could cause problems with your skin contour.
You're only real option is to have a bone reduction.
Some plastic surgeons maybe comfortable doing this procedures while others may not.
This procedure is also locational he done by oral surgeons who have training in maxiofacial surgery. 
best,
Mats Hagstrom M.D.

 Hi, I have performed many facial shaping procedures, including Facial Liposuction, Cheek Implants, Chin Liposuction and Chin Augmentation with dermal fillers or silastic chin implants, for over the 30 years.  Non smiling photos of your face from the front and side would help in the evaluation.  There is no significant fatty layer over the chin but there is fat below the chin in the neck that can be reduced using liposuction.  Liposuction should not be performed over the chin itself as it can result in muscle damage and skin contour irregularities.
Hope this helps.

An in-office exam would be required to ascertain what is best for you.  If you are referring to the bulge of skin under the jaw bone, then lipo may help.  If the chin is the problem, there are procedures that may help.  Seek out a board-certified Facial Plastic surgeon for a consult.  Best wishes.