Composition Process And Apparatus To Remove Sulfur From Refined Crude Oil Fraction

Abstract

A ionic liquid composition to remove sulfur from refined crude oil fraction, comprising or consisting of two or more compounds having: —an imidazolium cation substituted by one or more straight or branched C1-C6 alkyl group and —an anion selected from the group consisting of R5COO, CI., Br, [BF4], [PF6]—, [SbF6]—, [R6SO4], [OTs], [OMs], wherein R5 is C1-C8 alkyl, Cs—Cs cycloalkyl, benzyl, C2-C6 alkenyl, and R6 is C1-C6 alkyl.

Description

FIELD OF THE INVENTION[0001]The present invention relates to a composition, a process and an apparatus to remove sulfur from refined crude oil fraction, in particular from heavy fuel oils, more in particular from fuel oils used in marine transportation.BACKGROUND OF THE INVENTION[0002]Crude oil is a complex mixture of hydrocarbon compounds, generally viscous, dark greenish-brown fluids due to the variety of compounds present in them. The physical properties including viscosity, volatility and density, vary considerably depending upon the source. The proportion of elements in crude oil generally varies in the following ranges: carbon (83-87%), hydrogen (10-14%), sulfur (0.02-8%), nitrogen (0.1-2%), oxygen (0.05-1.5%) with small quantities of metallic constituents such as vanadium and nickel which are less than 1000 ppm. Sulfur, oxygen, nitrogen and metals make up most impurities found in crude oil. The sulfur content of crude oil is an important characteristic which effects the oil p...

AI Technical Summary

Benefits of technology

This patent aims to improve the process of removing sulfur from crude oil fractions using an ionic liquid composition. The technical effects of the invention include increased sulfur removal, shortened extraction time, and reduced costs related to desulfurization.

Problems solved by technology

Sulfur contained in the refined crude oil fraction is converted by combustion to SOx, which is a major source of acid rain, thus the presence of sulfur species is clearly a major issue in air pollution, airborne particulate emission and public health.

None of the methods reported above are able to eliminate completely S-compounds from fuels.

The operational temperature of the hydrotreater is commonly in the range of 300-380° C. and the pressure is above 30 bar, thus this method requires high energy and consumes large amount of hydrogen.

Conventional solvents have limitations in terms of environmental issue and recycle ability, as a difficulty with the technique is regenerating the extractive solvent.

As reviewed by Javadi, R et al. in Appl Petrochem Res (2012), 1:3-19, few of the known technologies are viable and / or efficient for the desulfurization of heavy oil, mainly due to the properties of heavy oil itself.

Javadli et al. reports that although ionic liquids have a high distribution coefficient for sulfur compounds such as dibenzothiophene in model mixtures, the distribution coefficient in real straight run distillate is rather low, and even worse in heavy fuel oils; therefore, ionic liquid are not ideal solvents for extractive desulfurization of real straight run distillates, in heavy oil the situation becomes worse.

Moreover, as ionic liquids are high boiling solvent, the recovery of extracted sulfur compounds is more challenging than with organic solvents.

For example, direct removal of sulfur compounds from ionic liquids by distillation is not applicable to heavy oil as the boiling point of heavier organosulfur compounds present in the heavy oil, such as alkylated dibenzothiophenes, are high (>340° C.) and it would require vacuum distillation.

Addition of water to ionic liquids to reduce the distribution coefficient of sulfur compounds in ionic liquids requires the final removal the water, a step which requires energy consumption.

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