Naphtha hydroprocessing with mercaptan removal

Abstract

This invention relates to the hydroprocessing of naphtha with removal of mercaptan from product. Naphtha feedstock is hydrotreated and hydrocracked. Sulfur-containing contaminants, notably C5+ recombinant mercaptans, are then selectively removed from the hydrocracked naphtha by selective extraction or adsorption.

Description

CROSS-REFERENCE TO RELATED APPLICATION [0001] This application claims benefit of U.S. Provisional Patent Application Ser. No. 60 / 582,112 filed Jun. 23, 2004.FIELD OF THE INVENTION [0002] This invention relates to the hydroprocessing of naphtha with removal of mercaptan from product. More particularly, naphtha feedstock is hydrotreated and hydrocracked. Sulfur-containing contaminants are then selectively removed from the naphtha. BACKGROUND OF THE INVENTION [0003] Environmental regulations covering the sulfur content of fuels for internal combustion engines are becoming more stringent with regard to allowable sulfur in fuels. It is anticipated that motor gasoline sulfur content may need to meet a sulfur limit of 30 wppm by 2004 with possible further reductions mandated in the future. The feedstocks for motor gasoline are typically catalytically cracked naphthas that contain substantial amounts of sulfur and olefins. [0004] A common method for reducing the sulfur content of feedstocks...

AI Technical Summary

Benefits of technology

The present invention provides a process for removing mercaptans from a hydrotreated naphtha without the need for further hydrotreatment and with improved octane value and yield. The process involves hydrotreating the naphtha feed, conducting a cracking zone and hydrocracking the hydrotreated naphtha with a hydrocracking catalyst, and contacting the hydrocracked naphtha with a treatment composition containing water, alkali metal hydroxide, cobalt phthalocyanine sulfonate, and alkylphenols. The treatment composition can have at least two phases, and the upgraded naphtha obtained after separation of the phases has less recombinant mercaptans. The process can also involve fractionating the naphtha feed prior to the hydrotreating step.

Problems solved by technology

However, such severe hydrotreating conditions normally result in a loss of molecules contributing to desirable octane properties either by cracking to non-fuel molecules or hydrogenation of olefins to molecules having lower octane rating.

However, such adjustments result in further loss of desirable molecules contributing to high octane.

This then results in increased production costs to produce high octane fuels because of the need to boost octane through added process steps such as isomerization, blending or addition of octane boosting additives.

Naphtha is first hydrotreated which results in some octane loss.