method for reducing sulfur compounds and nitrogen concentrations in oil oil

摘要

A method for the removal of sulfur and nitrogen components from petroleum oils is disclosed. The unwanted sulfur and nitrogen is oxidized to the extent that the resultant compounds exhibit preferential solubility characteristics in some solvent with respect to the oil. The oxidation step involves reacting the sulfur and nitrogen compounds present with an oxide of nitrogen. In particular instances, pretreatment of the oil to remove active groups which cause undesirable side reactions or removal of low sulfur fractions prior to the oxidation step will increase the efficiency of the process. The oil containing the oxidized forms of sulfur and nitrogen is then mixed with a selective solvent, which is immiscible in the oil and in which the sulfur and nitrogen compounds will dissolve. Methanol is the presently preferred solvent. Separation of the oil from the methanol-oxidized compound solution may be effected in a gravity separator. The oxidant gas may be regenerated by the addition of oxygen and recirculated. The oxidized sulfur and nitrogen compounds may be decomposed in a hydrolysis reaction with a dilute base to separate inorganic sulfate and sulfite, and nitrate and nitrite compounds from the hydrocarbon parts of the compounds.