Regeneration method for liquefied petroleum gas sweetening caustic

A regeneration method for caustic from sweetened liquefied petroleum gas, wherein the method comprises:

• under the action of a sulfonated cobalt phthalocyanine-based catalyst, subjecting caustic from sweetened liquefied petroleum gas to heat exchange before pumping into the liquid inlet of a Higee reactor;
• entering an oxygen-containing gas into the gas inlet of the Higee reactor, and mixing together the oxygen-containing gas and the liquid comprising the caustic and the catalyst in the Higee reactor to carry out an oxidation reaction to regenerate the caustic, wherein the volume ratio of the caustic to the oxygen-containing gas is 1:100-400, and the sulfonated cobalt phthalocyanine-based catalyst is added to the caustic at a concentration ranging from 10 mg/kg to 300 mg/kg,
• wherein the caustic from sweetened liquefied petroleum gas comprises mercaptan sodium and sodium sulfide, and
• wherein the caustic from sweetened liquefied petroleum gas is the caustic obtained after liquefied petroleum gas is sweetened by alkaline washing in a refining process,
• wherein while the oxidation reaction is carried out by mixing the caustic and the oxygen-containing gas in the Higee reactor and contacting with the oxidation catalyst, disulfide and polysulfide generated in the oxidation reaction are extracted into the gas phase under the condition of the caustic to gas volume ratio and the gas containing the disulfide and polysulfide is removed from the Higee reactor, resulting in caustic that has been regenerated.