  We investigate the metal-insulator Mott transition in a generalized version
of the periodic Anderson model, in which a band of itinerant electrons is
hybridrized with a narrow and strongly correlated band. Using dynamical
mean-field theory, we show that the precondition for a Mott transition is an
integer total filling of the two bands, while for an integer constant
occupation of the correlated band the system remains a correlated metal at
arbitrary large interaction strength. We picture the transition at a
non-integer filling of the correlated orbital as the Mott localization of the
singlet states between itinerant and strongly interacting electrons, having
occupation of one per lattice site. We show that the Mott transition is of the
first-order and we characterize the nature of the resulting insulating state
with respect to relevant physical parameters, such as the charge-transfer
energy.
