Selective treatment of FCC gasoline for removal of sulfur, nitrogen, and olefin compounds while maximizing retention of aromatic compounds

A method for the treatment of a naphtha range hydrocarbon feedstock comprising sulfur-containing compounds, nitrogen-containing compounds, olefins, diolefins, and aromatics, the method comprising:

• feeding hydrogen and the naphtha range hydrocarbon feedstock to a first stage reaction zone containing a first hydrotreatment catalyst;
• in the first stage reaction zone,
• contacting the hydrogen and the naphtha range hydrocarbon feedstock with the first hydrotreatment catalyst to convert sulfur-containing compounds to hydrogen sulfide, convert nitrogen-containing compounds to ammonia, and to hydrogenate diolefins;
• and
• recovering a first stage effluent;
• separating the first stage effluent to recover a gas stream comprising hydrogen sulfide, ammonia, and unreacted hydrogen and a liquid stream comprising hydrocarbons;
• separating the liquid stream to recover a C5 hydrocarbon fraction and a C6+ hydrocarbon fraction;
• feeding hydrogen and the C6+ hydrocarbon fraction to a second stage reaction zone containing a second hydrotreatment catalyst;
• in the second stage reaction zone,
• contacting the hydrogen and the first stage effluent with the second hydrotreatment catalyst to convert sulfur-containing compounds to hydrogen sulfide, convert nitrogen-containing compounds to ammonia, and hydrogenate olefins;
• and
• recovering a second stage effluent;
• partially degassing the second stage effluent to recover an off gas and a partially degassed second stage effluent;
• feeding the partially degassed second stage effluent to a stripper, separating and recovering an overheads fraction comprising the hydrogen sulfide, ammonia, and any unreacted hydrogen from a bottoms fraction comprising effluent hydrocarbons;
• feeding the effluent hydrocarbons to a naphtha splitter, separating and recovering an olefin lean overheads fraction comprising hydrocarbons boiling in a light cracked naphtha range and an aromatics rich fraction comprising hydrocarbons boiling in a heavy cracked naphtha range,
• wherein:
• less than 2 wt % aromatics are hydrogenated in the first and second stage reaction zones;
• the olefin lean overheads fraction comprises less than 0.2 wt % olefins and less than 100 mg/kg sulfur;
• the aromatics rich fraction comprises less than 50 ppmw olefins, less than 0.5 ppmw sulfur and less than 0.5 ppmw nitrogen.

A method for the treatment of a naphtha range hydrocarbon feedstock comprising sulfur-containing compounds, nitrogen-containing compounds, olefins, diolefins, and aromatics, the method comprising:

• feeding hydrogen and the naphtha range hydrocarbon feedstock to a first stage reaction zone containing a first hydrotreatment catalyst;
• in the first stage reaction zone,
• contacting the hydrogen and the naphtha range hydrocarbon feedstock with the first hydrotreatment catalyst to convert sulfur-containing compounds to hydrogen sulfide, convert nitrogen-containing compounds to ammonia, and to hydrogenate diolefins;
• and
• recovering a first stage effluent,
• wherein the naphtha range hydrocarbon feedstock is preheated upstream of the first stage reaction zone via indirect heat exchange with the aromatics rich fraction and direct heat exchange with a portion of the first stage effluent;
• feeding hydrogen and the first stage effluent to a second stage reaction zone containing a second hydrotreatment catalyst;
• in the second stage reaction zone,
• contacting the hydrogen and the first stage effluent with the second hydrotreatment catalyst to convert sulfur-containing compounds to hydrogen sulfide, convert nitrogen-containing compounds to ammonia, and hydrogenate olefins;
• and
• recovering a second stage effluent;
• partially degassing the second stage effluent to recover an off gas and a partially degassed second stage effluent;
• feeding the partially degassed second stage effluent to a stripper, separating and recovering an overheads fraction comprising the hydrogen sulfide, ammonia, and any unreacted hydrogen from a bottoms fraction comprising effluent hydrocarbons;
• feeding the effluent hydrocarbons to a naphtha splitter, separating and recovering an olefin lean overheads fraction comprising hydrocarbons boiling in a light cracked naphtha range and an aromatics rich fraction comprising hydrocarbons boiling in a heavy cracked naphtha range;
• wherein:
• less than 2 wt % aromatics are hydrogenated in the first and second stage reaction zones;
• the olefin lean overheads fraction comprises less than 0.2 wt % olefins and less than 100 mg/kg sulfur;
• the aromatics rich fraction comprises less than 50 ppmw olefins, less than 0.5 ppmw sulfur and less than 0.5 ppmw nitrogen.