Merox™ Treatment
Technical Profile
Merox™ is a UOP process to sweeten products by extracting and/or converting mercaptan sulfur to less objectionable disulfides. It is often used to treat products such as liquefied petroleum gases, naphtha, gasoline, kerosene, jet fuel and heating oils.
Hydrogen sulfide free feed is contacted with caustic in a counter-current extraction column. Sweet product exits the column overhead and caustic/extracted mercaptans exit the column bottom as extract. Air and possibly catalyst are mixed with extract and sent to an oxidation reactor where caustic is regenerated and mercaptans are converted to disulfides. Disulfides are insoluble in water and can be removed in a product separator that vents excess air and gas for disposal or destruction and separates sulfide oil, which may be returned to the refining process, from regenerated caustic, which is returned to the extraction column. Over time caustic will become spent and must be wasted to other refinery uses or to spent caustic destruction.
When removal of mercaptan sulfur is not required, "sweetening" may be applied to improve odor where mercaptan sulfur is converted to disulfide and carried out with the petroleum product. For sweetening, dilute caustic is added to the product prior to air injection. Combined feed enters a fixed bed reactor where a catalyst oxidizes mercaptan sulfur into disulfides. Caustic is removed from the bottom of the reactor and wasted to the sewer or spent caustic treatment.
