Yes, LIBERATE is a Scrabble word!

Letter values in Scrabble US: L 1, I 1, B 3, E 1, R 1, A 1, T 1, E 1.

Is it a valid word?

LIBERATE is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

give equal rights to; of women and minorities
grant freedom to; free from confinement
grant freedom to
release (gas or energy) as a result of a chemical reaction or physical decomposition

Also: set free.