bent on vs bent

bent on is not a noun while bent is a noun.

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

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

Other synonyms of bent on include dead set, out to.

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