Process for removing low amounts of organic sulfur from hydrocarbon fuels

A process for removing sulfur compounds from gasoline fuel comprising the steps of:

• contacting the gasoline fuel at a temperature of from about 90° C. to about 105° C. for a period of time up to about 15 minutes with an oxidizing solution comprising:
• from about 79 wt % to about 89 wt % formic acid,
• from about 2 wt % to about 3 wt % hydrogen peroxide, and
• from about 8 wt % to about 14 wt % water;
• in an amount such that the molar ratio of formic acid to hydrogen peroxide is from about 20:1 to about 60:
• 1, wherein the amount of oxidizing solution added is such that there is a stoichiometric excess of hydrogen peroxide necessary to oxidize the sulfur present in the gasoline fuel in an amount of from about 2.5 to about 3.5 times the amount needed to oxidize the sulfur in the fuel;
• extracting, during the oxidizing step, the oxidized sulfur compounds from the gasoline fuel into the aqueous oxidizing solution to form a hydrocarbon phase and an aqueous phase;
• separating the aqueous phase containing the extracted sulfur compounds from the hydrocarbon fuel phase;
• neutralizing any residual acid in the fuel;
• recovering the neutralized gasoline fuel containing less than about 25 ppm sulfur.

A process for removing sulfur compounds from a gasoline hydrocarbon fuel containing thiophenes, benzothiophenes, and alkyl-substituted thiophenes, and benzothiophenes without affecting the octane rating of the hydrocarbon fuel comprising the steps of:

• contacting, at a temperature of from about 65° C. to about 110° C., the sulfur-containing fuel with an aqueous oxidizing solution comprising hydrogen peroxide and formic acid in a mole ratio of at least about 11:1, formic acid to hydrogen peroxide, and having a content of from about 8 wt % to about 20 wt % water, in an amount such that the hydrogen peroxide present in greater than about 2 times the stoichiometric amount required to convert the sulfur compounds present to corresponding sulfones whereby a hydrocarbon fuel phase is formed which contains oxidized alkyl-substituted benzothiophenes, as sulfones, and an aqueous phase containing substantially all the oxidized benzothiophenes in the form of the corresponding sulfones;
• separating the aqueous phase containing the extracted, oxidized benzothiophene sulfur compounds from the hydrocarbon phase containing oxidized alkyl- substituted benzothiophenes in the form of the corresponding sulfones;
• neutralizing and dewatering the hydrocarbon phase;
• passing the hydrocarbon phase through a bed of an alumina adsorbent to adsorb the oxidized alkyl-substituted benzothiophenes and dibenzothiophenes from the fuel;
• and
• recovering the fuel having substantially lowered sulfur content from the oxidized sulfur compounds.