Photochemical Desulfurization and Denitrogenation Process for Vacuum Gas Oil Using an Organic Two-Phase Extraction System

Abstract

The simultaneous removal of sulfur-and nitrogen-containing compounds from vacuum gas oil (VGO), based on the combination of UV irradiation and liquid-liquid extraction using an oil/ acetonitrile two-phase system, has been investigated. Detailed desulfurization and denitrogenation reactivities for the various compounds in VGO have also been studied by means of field ionization mass spectrometry (FI-MS) and gas chromatography with atomic emission detection (GC-AED), respectively. When VGO and acetonitrile are mixed and photoirradiated, the sulfur and nitrogen compounds in the VGO are distributed into the acetonitrile phase and photodecomposed there to form highly polarized compounds, which do not distribute into the lowerpolarity VGO. The successive removal of these compounds from VGO to acetonitrile can therefore be carried out under moderate conditions, such that the sulfur and nitrogen contents for the VGO are decreased simultaneously to less than 1% of the feed values. FI-MS and GC-AED analyses reveal that dinaphthothiophenes, tetrahydrodinaphthothiophenes, tetrahydrodibenzothiophenes, and carbazoles, having large carbon numbers of the alkyl substituents, are the most difficult compounds to remove by the present photochemical organic two-phase extraction process. The removal efficiencies for sulfur and nitrogen compounds obtained from VGO were compared with the results obtained for light oil feedstocks, and the applicability of the present process to the refining of VGO was examined. From a consideration of the above results, a fully organized overall refining process for petroleum-derived middle and heavy feedstocks has been developed.

Extractive Desulfurization of Fuel Oils with Thiazolium-Based Ionic Liquids

“…In addition, HDS generally requires high temperature (>300 C), high pressure (>4 MPa), consumption of H 2 and catalyst, etc (5,6). Therefore, various alternative or complementary desulfurization processes have been investigated to remove the HDS-immune S-compounds, for example, extractive (7)(8)(9)(10)(11)(12)(13)(14)(15)(16), oxidative (17)(18)(19), adsorptive, (20,21) and biodesulfurizations (22,23). Among them, extractive desulfurization seems more eye-catching because it does not require hydrogen and catalyst and its operation condition is mild; moreover, it does not alter the chemical structure of the compounds in fuel oils and the extracted S-compounds can be re-used as raw materials.…”

“…Very different from traditional molecular-type organic solvents, ILs are entirely composed of cations and anions, and possess some novel and desirable properties such as non-volatility, excellent selective solvent power for organic=inorganic compounds, good thermal=chemical stability, nonflammablity, etc (27,28). It is observed that ILs are almost insoluble in fuel oil and favorably disposed towards the extraction of thiophenic S-compounds, such as TS and DBT, over other aliphatic or aromatic compounds (11,12,29). Many ILs used in extractive desulfurization are mostly imidazolium-and pyridinium-based, coupled with anions such as tetrafluoroborate= [BF 4 ], hexafluorophosphate=[PF 6 ], chloride-based [Cl=AlCl 3 ], and [Cl=FeCl 3 ], bis(trifluoromethylsulfonyl)imide=[Tf 2 N], alkylsulfate, and alkylphosphate (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18).…”

Photocatalytic oxidative desulfurization of dibenzothiophene under simulated sunlight irradiation with mixed-phase Fe2O3 prepared by solution combustion

“…Their works include the study on product identification and the effect of photosensitizer benzophenone on sulfur removal. [12][13][14][15][16] To improve sulfur removal, researchers also used TiO 2 as photocatalyst [17][18][19][20][21][22] because of its nontoxicity, chemical and photochemical stability, low cost, and excellent photocatalytic activity. 23,24 Above mentioned studies were all performed by UV light irradiation because the sulfur-containing compounds cannot be photodegraded itself under visible light.…”

PREPARATION AND CHARACTERIZATION OF Cu-Fe/TiO2 PHOTOCATALYST FOR VISIBLE LIGHT DEEP DESULFURIZATION

“…The application of this photochemical oxidation to desulfurization as been realized in some literatures [22,23] using oil-water and oil-polar solvent two phase systems. The desulfurization of light oil to a sulfur content of less than 0.05 wt% has been achieved successfully.…”