  There is a class of binary post-AGB stars (binary system including a post-AGB
star) that are surrounded by Keplerian disks and outflows resulting from gas
escaping from the disk. To date, there are seven sources that have been studied
in detail through interferometric millimeter-wave maps of CO lines
(ALMA/NOEMA). For the cases of the Red Rectangle, IW Carinae, IRAS 08544-4431,
and AC Herculis, it is found that around greater than 85% of the total nebular
mass is located in the disk with Keplerian dynamics. The remainder of the
nebular mass is located in an expanding component. This outflow is probably a
disk wind consisting of material escaping from the rotating disk. These sources
are the disk-dominated nebulae. On the contrary, our maps and modeling of 89
Herculis, IRAS 19125+0343, and R Scuti, which allowed us to study their
morphology, kinematics, and mass distribution, suggest that, in these sources,
the outflow clearly is the dominant component of the nebula (around 75% of the
total nebular mass), resulting in a new subclass of nebulae around binary
post-AGB stars: the outflow-dominated sources.Besides CO, the chemistry of this
type of source has been practically unknown thus far. We also present a very
deep single-dish radio molecular survey in the 1.3, 2, 3, 7, and 13 mm bands
(around 600 h of telescope time). Our results and detections allow us to
classify our sources as O- or C-rich. We also conclude that the calculated
abundances of the detected molecular species other than CO are particularly
low, compared with AGB stars. This fact is very significant in those sources
where the rotating disk is the dominant component of the nebula.
