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“Why can we remember the tiniest detail that has happened to us, and not remember how many times we have told it to the same person.” -- François de la Rochefoucauld (French classical author, leading exponent of the Maxime, 1613-1680)

Two free full text desulfurization items of interest … a patent, and an article from the amazing Hindawi (http://www.hindawi.com/) open access journals database.

Details below …
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PATENT
Desulfurization of hydrocarbons by Ionic liquids and preparation of ionic liquids (Instituto Mexicano Del Petroleo)
Publication number
US20130118955 A1
Publication type
Application
Application number
US 13/733,173
Publication date
May 16, 2013
DE102009022284A1, US20090288992
Inventors
Natalya Victorovna Likhanova, Rafael Martinez Palou, Jorge Froylan Palomeque Santiago
Original Assignee
Instituto Mexicano Del Petroleo
Abstract
The present invention relates to an improved desulfurization process using an ionic liquid compound of general formula C+A−, where C+ represents an organic cation such as alkyl-pyridinium, di-alkyl imidazolium and tri-alkyl imidazolium; and A− is an anion of halides of iron (III), such as, for example, FeCl4 −. The desulfurization process is also improved when producing the ionic liquid compound by heating the reactants using microwave energy. The ionic liquids can be used to desulfurize hydrocarbon mixtures by a liquid-liquid extraction.
FIELD OF THE INVENTION
This invention provides a process for the synthesis of ionic liquids which can be used for the efficient removal of sulfur compounds from hydrocarbon mixtures. The ionic liquids related are insoluble in hydrocarbons but are able to dissolve aliphatic and aromatic sulfur compounds. Thus, the ionic liquids can be used for removal of sulfur compounds by a liquid-liquid extraction process at room temperature and pressure. The invention is also directed to a process for extracting sulfur from a hydrocarbon liquid by contacting the hydrocarbon with the ionic liquid.
More preferably, this invention is related to the synthesis of ionic liquids with general formula C+A−, where C+ is an organic cation preferably but not exclusively alkyl pyridinium, dialkylimidazolium, and trialkylimidazolium, the anion A− is preferably halogen ferrate (III), particularly Cl*FeCl3 − and Br*FeCl3. The invention is also directed to the process for the extraction of sulfur-containing compounds, such as sulfur compound that are present in gasoline and Diesel as contaminant obtained in petroleum refining processes by contacting with the ionic liquids.
BACKGROUND OF THE INVENTION
The production of gasoline according with the new European Environmental Standards requires that the refiners to lower the sulfur content in gasoline to values that are lower than 50 ppm since 2005. For example in Germany he content of sulfur in gasoline should be lower than 10 ppm. For the case of USA the content of sulfur is limited to lowest than 80 ppm and with average of 30 ppm. In attention to this claims, PEMEX Refining should be produce gasoline with sulfur content between 15 and 30 ppm for the years 2008-2010.
The classic method used for sulfur removal in Refining Processes is the catalytic Hydrodesulfurization (HDS technology) at high temperature and pressure. This method is very costly process that required drastic operation conditions and it is inefficient to reduce aromatic sulfur compounds especially for Mexican heavy crude oil, so is more reasonable the use of alternative desulfurization process. For increasing the efficiency of HDS process some technology modification are required such as the addition of other catalytic bed, more efficient catalyst, higher temperature and pressures and to reduce LHSV to expense of few processing capacity.
New technologic lines have been develop on in several countries in order to resolve this problem (Zaczepinski, S. Exxon, Diesel Oil Deep Desulfurization (DODD) in Handbook of Petroleum Refining Processes, ed. R. A. Meyer, Mc Graw-Hill, NY, 1996, Ch. 8.7), i.e.: the absorption of sulfur compounds over solid absorbents, like IRVAD® process (U.S. Pat. No. 5,730,860, dated Mar. 24, 1998) from Black & Veatch Pritchard Inc.; the process S-Zorb® from Phillips Petroleum (http://www.eia.doe.gov/oiaf/servicerpt/ulsd/uls.html), the process Haldor Topsoe (EP 1057879, dated Dec. 6, 2000); and the liquid-liquid extraction with volatile organic solvents (Petrostar Refining, 217 National Meeting, American Chemical Society, Anaheim, Calif., Marzo, 1999). An original process is the oxidative desulfurization with different oxidant agents (Unipure Corp., NPRA Meeting No AM-01-10, Marzo 2001; Sulphco Corp, NPRA Meeting No AM-01-55, March 2001; BP Chemicals UK, Journal of Molecular Catalysis A: Chemical (1997) 397-403; UOP LLC, U.S. Pat. No. 6,171,478, dated Jan. 9, 2001; EXXON Research and Engineering Co., U.S. Pat. No. 5,910,440, dated Jun. 8, 1999; U.S. Patent Publication No. 2002/0035306 A1 with publication date of Mar. 21, 2002; U.S. Pat. No. 6,596,914 B2, dated Jul. 22, 2003; U.S. Pat. No. 6,406,616, dated Jun. 18, 2002 and U.S. Pat. No. 6,402,940 B1 dated Jun. 11, 2002; Fuel 82 (2003) 4015; Green Chemistry 5 (2003) 639). Recently the extraction of sulfur-containing compounds using liquid-liquid extraction employing ionic liquids have been welcome by scientific community.
Ionic liquids are known for more than 30 years, but their industrial applications began in the last 10 years (Rogers, R. D.; Seddon, K. R (Eds.), Ionic Liquids: Industrial Applications of Green Chemistry, ACS, Boston, 2002). They are applied as solvents and catalyst in alkylation reactions, polymerization and Diels-Alder cycloaddition. In addition they are employed in electrochemical processes, in supercritical CO2 extraction of aromatic compounds and sulfur compounds in hydrocarbon mixtures. One of the first publications mention the use of ionic liquids for the removal of mercaptans (WO 0234863, dated May 2, 2002). The patented method is based on the use of sodium hydroxide in combination with ionic liquids for the conversion of mercaptans to mercaptures, which were removed using ionic liquids. Peter Wassercheid and coworkers published several papers and patents between 2001 and 2005 about the use of ionic liquids for desulfurization of gasolines (Chem. Comun. (2001) 2494; WO 03037835, with publication date of 2003 May 8; U.S. Publication No. 2005/0010076 A1, published Jan. 13, 2005). In these works the authors employed ionic liquids with C+ being 1,3-dialkylimidazolium or tetralkylammonium, and A− being tetrachloroaluminates or methanesulfonates. By means of a process with several extractions (up to 8 extractions), high extraction of sulfur compounds were achieved using model gasolines. However these kinds of compounds are air and moisture sensitive and a polymerization reaction was observed during the extraction process. U.S. Patent Publication No. 2003/0085156 A1 published May 8, 2003 and U.S. Pat. No. 7,001,504, dated Feb. 21, 2006, also mention the use of ionic liquids, where C+ is an ammonium o fosfonium and quaternary, A− being tetrachloroaluminates for the extraction of sulfur from model gasoline. In the paper published in Energy & Fuels 18 (2004) 1862, the use of ionic liquids containing Copper chloride (I) anion with the same application, and in the papers Ind Eng. Chem. Res. 43 (2004) 614 and Ind. Eng. Chem. Res. 46 (2007) 5108-5112) several ionic liquids were evaluated for the extraction of sulfur and nitrogen-containing compounds. More recently, some papers (Energy & Fuels 20 (2006) 2083-2087; Green Chemistry 8 (2006) 70-77; Progress in chemistry 19 (2007) 1331-1344; Green Chemistry 10 (2008) 87-92) also report the use of IL for desulfurization processes. U.S. Patent Publication No. 2004/00445874 A1, published Mar. 11, 2004, discloses a procedure for desulfurization and denitrogenation of hydrocarbons fractions using a wide family of ionic liquids and alkylations agents with high efficiency in some cases.
SUMMARY OF THE INVENTION
The present invention is directed to the use of ionic liquids containing halogens of Fe (III) as an anion for these purposes, where these compounds presented very high efficiency for extracting sulfur-containing compounds from gasoline, turbosin, diesel and other petroleum fractions. Another important and novel aspect of the invention is the use of microwave irradiation for synthesizing the ionic liquids suitable for use as extracting agents (symmetric and non-symmetric compounds) with a corresponding shorter time and higher yields in the synthesis of these ionic liquids compared to the conventional methods of synthesis.
The invention is also directed to a process for extracting sulfur and sulfur compounds from a sulfur-containing hydrocarbon liquid by contacting the hydrocarbon liquid with an ionic liquid of the invention for sufficient time to extract the sulfur and sulfur-containing compounds, and thereafter recovering the hydrocarbon liquid.
The ionic liquids of the invention comprise a heterocyclic cation and an iron (III) halide. The heterocyclic cation is an imidazolium compound having at least one C1-C10 alkyl group or alkoxy group where the alkyl group and alkoxy group can be linear, branched, substituted or unsubstituted. The heterocyclic cation can be symmetrical or asymmetrical.
Free Full Text Source: http://www.google.com/patents/US20130118955

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International Journal of Chemical Engineering, Volume 2013, Article ID 951045, 10 pages, http://dx.doi.org/10.1155/2013/951045
Investigation of Influential Parameters in Deep Oxidative Desulfurization of Dibenzothiophene with Hydrogen Peroxide and Formic Acid
Alireza Haghighat Mamaghani, Shohreh Fatemi, andMehrdad Asgari
shfatemi@ut.ac.ir
School of Chemical Engineering, College of Engineering, University of Tehran, Enghelab Avenue, P.O. Box 11155-4563, Tehran 11155-4563, Iran
Abstract
An effective oxidative system consisting of hydrogen peroxide, formic acid, and sulfuric acid followed by an extractive stage were implemented to remove dibenzothiophene in the simulated fuel oil. The results revealed such a great performance in the case of H2O2 in the presence of formic and sulfuric acids that led to the removal of sulfur compounds. Sulfuric acid was employed to increase the acidity of media as well as catalytic activity together with formic acid. The oxidation reaction was followed by a liquid-liquid extraction stage using acetonitrile as a polar solvent to remove produced sulfones from the model fuel. The impact of operating parameters including the molar ratio of formic acid to sulfur (nF/nS), hydrogen peroxide to sulfur (nO/nS), and the time of reaction was investigated using Box-Behnken experimental design for oxidation of the model fuel. A significant quadratic model was introduced for the sulfur removal as a function of effective parameters by the statistic analysis.
Using hydrogen peroxide with an acid has been widely investigated by several researchers. However, to the best knowledge of the authors, there are few studies which are concerned with optimizing the process parameters. The objective of the present work is to develop an efficient system for oxidative desulfurization of model fuel. ODS of dibenzothiophene (DBT) in n-octane as simulated fuel was performed in the presence of H2O2, formic acid, and H2SO4 as the oxidation system. After the oxidation step, a twostep liquid-liquid extraction with acetonitrile was applied to remove the oxidated sulfur compounds from the model fuel. Influences of operating conditions including H2O2/S molar ratio, acid formic/S molar ratio, oxidation duration time, and mediumaciditywere examined.Theextraction step was carried out at the same conditions in all experiments. Box-Behnken experimental design was implemented as a kind of response surface methodology (RSM) to arrange the experiments and develop amodel to explain the relationships of sulfur removal and the studied parameters and finally optimize the operating conditions.
Free Full Text Source: http://www.hindawi.com/journals/ijce/2013/951045/abs/