bent vs bent on

bent is a noun but bent on is not a noun.

Word	Noun	Adjective	Verb	Adverb
bent	Yes	Yes	No	No
bent on	No	Yes	No	No

As adjectives, bent and bent on are synonyms defined as:

Other synonyms of bent include dead set, out to.

bent (noun)	bent on (noun)
a special way of doing something
a relatively permanent inclination to react in a particular way
an area of grassland unbounded by fences or hedges
grass for pastures and lawns especially bowling and putting greens

bent (adjective)	bent on (adjective)
of metal e.g.	fixed in your purpose
fixed in your purpose
used of the back and knees; stooped