  The only known examples of noncompact Einstein homogeneous spaces are
standard solvmanifolds (special solvable Lie groups endowed with a left
invariant metric), and according to a long standing conjecture, they might be
all. The classification of Einstein solvmanifolds is equivalent to the one of
Einstein nilradicals, i.e. nilpotent Lie algebras which are nilradicals of the
Lie algebras of Einstein solvmanifolds. Up to now, there have been found very
few examples of graded nilpotent Lie algebras that can not be Einstein
nilradicals. In particular, in each dimension, there are only finitely many
known. We exhibit in the present paper two curves of pairwise non-isomorphic
9-dimensional 2-step nilpotent Lie algebras which are not Einstein nilradicals.
