Can I operate a 120VAC contactor with a DC power supply
DC can be used for AC contactor coils, but you will need to determine the voltage and current by testing. There is a good possibility that the voltage and current required to get the contactor to pull in may cause the contactor coil to overheat is maintained continuously. That will require an "economizer circuit" to reduce the current after the contactor has pulled in.

Some contactors have coils or core and coil assemblies that can be replaced with DC components. That would at least provide known coil characteristics. You may still need an economizer circuit.

If you can't use AC, what will the contactors be switching? AC contactors are very limited in their ability to switch DC current.

If you are asking about parallel coils, there is no problem with that, but each coil will need its own economizer circuit.