Embodiments of apparatuses and methods for conversion of mercaptans are provided. In one example, an apparatus comprises a vessel that is capable to receive a feed stream that comprises liquid hydrocarbons and the mercaptans. The vessel comprises a catalyst bed section that is capable of contacting the feed stream with a catalyst in the presence of oxygen (O2) and caustic at reaction conditions effective to oxidize the mercaptans and form a caustic-containing, sweetened liquid hydrocarbon-containing stream. A coalescing bed section is capable to coalesce and separate at least a portion of the caustic from the caustic-containing, sweetened liquid hydrocarbon-containing stream for forming a caustic-depleted, sweetened liquid hydrocarbon-containing product stream.