  We study the motility-induced phase separation of active particles driven
through the interconversion of two chemical species controlled by ideal
reservoirs (chemiostats). As a consequence, the propulsion speed is
non-constant and depends on the actual inter-particle forces, enhancing the
positive feedback between increased density and reduced motility that is
responsible for the observed inhomogeneous density. For hard discs, we find
that this effect is negligible and that the phase separation is controlled by
the average propulsion speed. For soft particles and large propulsion speeds,
however, we predict an observable impact on the collective behavior. We briefly
comment on the reentrant behavior found for soft discs. Finally, we study the
influence of non-constant propulsion on the sedimentation profile of
non-interacting active particles.
