A unit for processing a liquid/gas phase mixture, a mercaptan oxidation apparatus, and a method of processing a liquid/gas phase mixture are provided. In an embodiment, a unit for processing a liquid/gas phase mixture includes a vessel that is adapted to receive the liquid/gas phase mixture and a distributor that is disposed in the vessel. The distributor is adapted for flow of the liquid/gas phase mixture into the vessel, and the distributor includes a first outlet pipe that is horizontally disposed within the vessel. The first outlet pipe includes top orifices and bottom orifices that are spaced along the first outlet pipe, and the first outlet pipe is in fluid communication with the vessel through the top orifices and the bottom orifices. The top orifices have a smaller cross-sectional area than the bottom orifices.