| abstract |
A method of the removal of sulfur from petroleum oils in which the sulfur in the oils is oxidized in part with an oxide of nitrogen to form gaseous sulfur compounds (e.g., SO2, SO3). The sulfur containing gas can then be further used by condensing and absorbing the sulfur trioxide in concentraded sulfuric acid. Water is then added to the resulting solution of SO3 and concentrated sulfuric acid (oleum) to form additional sulfuric acid as a product. The remaining sulfur compounds in the oil may be simultaneously oxidized by a suitable oxide of nitrogen to form sulfoxides which, if desired, can be removed to further reduce the sulfur content by mixing the oxidized oil with a selective solvent, such as methanol, which is immiscible in the oil and in which the oxidized sulfur compounds will dissolve. Separation of the oil from the methanol-sulfur oxidized compound solution can be accomplished in a gravity separator or the like. The oxidizing gas is regenerated by the addition of oxygen in the feed gas or in the make-up gas and recirculated to oxidize further feeds of petroleum oils. If required, certain pretreatment steps may be used before oxidizing the oil to reduce polymerization and other side reactions such as cracking. |