Selective liquid-liquid extraction of oxidative desulfurization reaction products

Abstract

The present invention provides selective extraction of sulfoxides, or sulfoxides in combination with sulfones, from hydrocarbon mixtures containing these compounds. A significant advantage of the invention is that oxidation products resulting from oxidative desulfurization of hydrocarbon feedstocks are selectively extracted with minimum co-extraction of non-oxidized products such as valuable hydrocarbon fuel components.

Description

RELATED APPLICATIONS[0001]This application claims the benefit of U.S. Provisional Patent Application No. 61 / 539,734 filed Sep. 27, 2011, the disclosure of which is hereby incorporated by reference in its entirety.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]This invention relates to a system and process for extraction of sulfoxides or a combination of sulfoxides and sulfones, and more particularly to a selective liquid-liquid system and method for the extraction of oxidative desulfurization reaction products from a hydrocarbon mixture.[0004]2. Description of Related Art[0005]It is well known that certain sources of crude oil known as “sour” crude contain significant amounts of sulfur. If chemically-combined sulfur, such as organosulfur compounds, is not removed from the resultant hydrocarbon products, including paraffins, olefins and aromatics, particularly gasoline, diesel or other fuels, its presence can cause corrosion of processing equipment and engine parts, ...

AI Technical Summary

Benefits of technology

This patent describes a process for selectively extracting sulfoxides and sulfones from hydrocarbon mixtures containing them. The process uses a selective solvent formulation that reduces co-extraction of non-oxidized products like valuable fuel components. The process can be carried out in a batch reactor, continuous flow reactor, tubular flow reactor, or liquid-liquid separator. The advantages of the process include reducing complexity and the number of extractive steps, minimizing sulfur dioxide production, and favoring sulfoxide production. Overall, the process selectively extracts oxidized sulfur while reducing the amount of untreated organosulfur compounds in the hydrocarbon feedstock.

Problems solved by technology

If chemically-combined sulfur, such as organosulfur compounds, is not removed from the resultant hydrocarbon products, including paraffins, olefins and aromatics, particularly gasoline, diesel or other fuels, its presence can cause corrosion of processing equipment and engine parts, as well as other deleterious effects, particularly when water is present.

Further, the discharge into the atmosphere of sulfur compounds during processing and end-use of the petroleum products derived from sour crude oil pose safety and environmental problems.

However, many existing hydroprocessing facilities, such as low pressure hydrotreaters, which represent substantial prior capital investment, were constructed before more stringent sulfur specifications were enacted.

It is very difficult to upgrade existing hydroprocessing systems because of the comparably more severe operational requirements (i.e., higher temperature and pressure) to obtain clean fuel production.

However, all retrofitting alternatives are limited by process economics and the basic existing hydrotreating system upon which they improve.

The addition of alkyl groups to the ring compounds increases the difficulty of hydrodesulfurization.

Dibenzothiophenes resulting from addition of another ring to the benzothiophene family are even more difficult to desulfurize, and the difficulty varies greatly according to their alkyl substitution, with di-beta substitution being the most difficult to desulfurize, thus justifying their “refractory” appellation.

Oxidation of certain sulfur-containing compounds increases their solubility in certain solvents.

It is likely that non-treated organosulfur compounds, other aromatics and other hydrocarbons are also co-extracted to a considerable degree, thereby detrimentally impacting product yield.

However, it is known that the polar solvent methanol has a significant affinity for non-treated sulfur compounds, aromatics and other hydrocarbons, thus reducing the overall product yield in a manner that may not be commercially acceptable.

While the processes described above can be effective to remove sulfoxides and / or sulfones from a hydrocarbon mixture, problems remain related to co-extraction of other valuable hydrocarbon components, thus reducing the overall hydrocarbon product yield.

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