  We show that an internal localization mobility edge can appear around the
Fermi energy in graphene by introducing impurities in the split-band regimen,
or by producing vacancies in the lattice. The edge appears at the center of the
spectrum and not at the band edges, in contrast with the usual picture of
localization. Such result is explained by showing that the bipartite nature of
lattice allows to renormalize the Hamiltonian, and the internal edge appears
because of frustration effects in the renormalized lattice. The size in energy
of the spectral region with localized states is similar in value to that
observed in narrow gap semiconductors.
