“Children are the most desirable opponents at scrabble as they are both easy to beat and fun to cheat.” -- Fran Lebowitz (American Writer and Humorist, b.1950)
A primary purpose of the Desulfurization Blog is to provide tips on how to make your online searching more efficient. Much of your searching involves Googling®. You can refine your Google searches by clicking the “Advanced” button and entering additional criteria to limit the search to more relevant results.
Here’s a time saver tip: Use the Google Cheat Sheet (http://www.google.com/help/cheatsheet.html) to enter the search string directly. This saves you a few keystrokes, which can add up when you are doing multiple searches.
The Google Cheats include …
Maui OR Hawaii ….. to find pages containing EITHER the word Maui OR the word Hawaii
“To each his own” ….. to find the EXACT PHRASE “To each his own”
Virus NOT computer … to find the word virus but NOT the word computer
+sock ….. to find only the word sock and not the PLURAL or any tenses or synonyms
~auto loan ….. to find loan info for BOTH the word auto and its synonyms: truck, car, etc.
Source: http://www.google.com/help/cheatsheet.html
There are many others. Visit the Cheat Sheet URL for more.
Here are two examples illustrating the use of Google special operators …
GOOGLE “+” EXAMPLE:
dibenzothiophene +patent 2010In this example, we search for items containing the word “patent” but not “patents” or “patentable”Browse the post to see one result
GOOGLE “-“ EXAMPLE:
dibenzothiophene -patent 2010In this example, we search for items containing the word “dibenzothiophene” EXCLUDING PATENTSBrowse the post to see one result
In each case we restricted the search further by including the year “2010”
///////
GOOGLE “+” EXAMPLE:
dibenzothiophene +patent 2010In this example, we search for items containing the word “patent” but not “patents” or “patentable”
///////
Patent application title:
ADSORPTION OF DIBENZOTHIOPHENES FROM HYDROCARBON AND MODEL DIESEL FEEDSInventors: Xiaolin Wei Marcus V. Dutra e Mello Daniel Chinn Zunqing He Scott M. Husson
Agents: CHEVRON CORPORATION
Assignees: Chevron U.S.A. Inc.
Origin: SAN RAMON, CA US
IPC8 Class: AC10G1702FI
USPC Class: 208219
Publication date: 06/17/2010
Patent application number: 20100147748
Abstract:
A process for adsorbing aromatic sulfur compounds, where an adsorbent is contacted with a C.sub.6-C.sub.20 aromatic and/or aliphatic stream which comprises a solution of (i) at least one benzothiophene compound, (ii) a solvent which comprises at least one C.sub.6-C.sub.16 aliphatic compound, and (iii) optionally at least one C.sub.6-C.sub.12 aromatic compound. In this process, the adsorbent is regenerated using an organic regenerant such as, but not limited to, toluene. Also disclosed is another process for adsorbing aromatic sulfur compounds. In this process, an adsorbent is contacted with a mixture comprising a model diesel feed comprising at least one benzothiophene compound. In this process, the adsorbent is regenerated using an organic regenerant such as, but not limited to, toluene.
FIELD OF THE INVENTION
[0001]The present invention is related to processes for adsorbing aromatic sulfur compounds from hydrocarbon and model diesel feeds.
BACKGROUND OF THE INVENTION
[0002]The removal of sulfur from gasoline fuel demands attention worldwide, not only because of the need to reduce atmospheric pollution by sulfur oxides, but also because of the need to make ultra-low sulfur fuels for hydrocarbon fuel processors used in fuel cell applications. EPA regulations put forward in 2001 require that gasoline sulfur content must be .ltoreq.30 ppmw, and highway diesel sulfur content should be .ltoreq.15 ppmw in 2009.
[0003]The common types of sulfur compounds in various distillate fuel fractions include sulfides, disulfides, thiols, thiophenes, benzothiophenes, methyl-benzothiophenes, dibenzothiophenes, and methyl-substituted dibenzothiophenes. The presence of sulfur compounds in commercial fuels is highly undesirable. These compounds are corrosive to metals, poison catalysts in hydrocarbon fuel processors, and they contaminate the environment in the form of sulfur oxides emitted in engine exhaust.
[0004]Currently, the extent of petroleum feedstock desulfurization depends on the catalytic hydrodesulfurization process (HDS), where the sulfur compounds lose sulfur by hydrogenation reactions, giving off H.sub.2S as one of the treatable products. Hydrotreating is a commercially proven and simple refining process, and refineries with hydrotreaters produce deeply desulfurized gas oil on straight-run distillates by modifying catalysts and operating conditions. However, greater challenges are expected for desulfurizing distillate streams such as Light Cycle Oil (LCO), requiring either substantial revamps to equipment or construction of new units. Specifically, hydrotreating LCO requires a higher reactor pressure, as well as an increased hydrogen rate and purity. Furthermore, distillates from Fluid Catalytic Cracking (FCC) operations contain higher concentrations of compounds with aromatic rings, which make deep desulfurization more difficult. For these reasons, new technology developments are needed for the ultra-deep desulfurization of these feedstocks.
[0005]In order to reduce the cost of deep-desulfurization, several new technologies have been introduced in the experimental stages. Among them, sulfur adsorption, sulfur oxidation and biodesulfurization seem to be quite promising. The major advantages of these new technologies include lower costs, lower processing temperatures and pressures, reduced emissions of gaseous pollutants and carbon dioxide, and no hydrogen requirement. In general, the sulfur adsorption processes use specific adsorbents that interact with the sulfur-containing compounds to separate them selectively from the hydrocarbon mixtures. This technology seems particularly favorable for gasoline desulfurization because the process does not modify the hydrocarbon components, thereby avoiding any loss in octane rating.
[0006]In commercial diesel, the major sulfur compounds are thiophene, benzothiophene, dibenzothiophene, and their alkyl derivatives. This fact indicates that the reactivities of alkyl-substituted benzothiophenes (BT) and dibenzothiophenes (DBT) are much lower during catalytic hydrotreating than those of other sulfur-containing molecules. Kabe et al. reported that although the alkyl group substitutions of DBT do not inhibit the adsorption of DBT's on catalysts via .pi.-electrons in the aromatic rings, the C--S bond cleavage of adsorbed DBT's is disturbed by steric hinderance of the alkyl group(s). Kabe, T.; Ishihara, A.; Zhang, Q. Deep desulfurization of light oil. Part 2: hydrodesulfurization of dibenzothiophene, 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene. Appl. Catal. A 1993, 97, L1-L9. Consequently, in the ultra-deep desulfurization process, the removal of these substituted DBT's is of greatest interest for refineries.
[0007]Because DBT's are electron rich, they form charge transfer complexes (CTC) with suitable electron acceptors. For this reason, reversible complexation of DBT's by .pi.-acceptors can be used as a separation strategy to recover DBT's. One technical challenge to overcome in order to use reversible complexation as the strategy for DBT removal from gasoils is that gasoils contain numerous other aromatic compounds that also can donate electrons to form CTC's with the acceptor compound. For this reason, the acceptor compound (or, more generally, the separation agent) needs to be selective toward the DBT's. To tackle this critical need, we have previously (i) prepared and tested a TAPA functionalized adsorbent that incorporates .pi.-acceptor groups known to be efficient and selective for binding DBT's; (ii) addressed that this adsorbent should maintain capacity in the presence of significant volume percentages of aromatics; and (iii) addressed that this adsorbent is regenerable (i.e. complexation is reversible), as fully described in commonly assigned, pending U.S. patent application Ser. No. 12/134,311, the entire disclosure of which is hereby incorporated by reference in its entirety. We now address three issues pertaining to the use of TAPA functionalized adsorbents: (i) adsorption of 4,6-DMDBT in the presence of competing aromatics, (ii) co-adsorption of 4,6-DMDBT and dibenzothiophene from model diesel, and (iii) solvent regeneration of adsorbents with a toluene regenerant.
SUMMARY OF THE INVENTION
[0008]One aspect of this invention is directed to one process for adsorbing aromatic sulfur compounds. In this process, an adsorbent is contacted with a C.sub.6-C.sub.20 aromatic and/or aliphatic stream which comprises a solution of (i) at least one benzothiophene compound, (ii) a solvent which comprises at least one C.sub.6-C.sub.16 aliphatic compound, and (iii) optionally at least one C.sub.6-C.sub.12 aromatic compound. In this process, the adsorbent is regenerated using an organic regenerant such as, but not limited to, toluene.
[0009]Another aspect of the invention is directed to another process for adsorbing aromatic sulfur compounds. In this process, an adsorbent is contacted with a mixture comprising a model diesel feed comprising at least one benzothiophene compound. In this process, the adsorbent is regenerated using an organic regenerant such as, but not limited to, toluene.
source: http://www.faqs.org/patents/app/20100147748
///////
GOOGLE “-“ EXAMPLE:
dibenzothiophene -patent 2010In this example, we search for items containing the word “dibenzothiophene” EXCLUDING PATENTS///////
Molecules 2010, 15, 1265-1269
doi:10.3390/molecules15031265
Desulfurization of Dibenzothiophene and Oxidized Dibenzothiophene Ring SystemsDiego P. Morales, Alexander S. Taylor and Steven C. Farmer *
Department of Chemistry, Sonoma State University, 1801 East Cotati Avenue, Rohnert Park, CA 94928, USA
∗ Author to whom correspondence should be addressed; E-Mail: farmers@sonoma.edu; Tel.: +1-707-664-3728.
1. Introduction
The reductive desulfurizations of various types of organosulfur compounds are of importance in industry, mainly because of their application in the desulfurization of fossil fuels to reduce pollution [1,2]. The desulfurization of polycyclic aromatic sulfur compounds such as benzo- and dibenzothiophenes are of particular interest because of their widespread occurrence in fossil fuels.
The desulfurization of polycyclic aromatic sulfur compounds also has applications in the laboratory [3–5]. Because the sulfur atom in such heterocycles has a strong directing effect towards electrophillic aromatic substitution reactions, the subsequent desulfurization could provide a regioselective entry to substituted biphenyls and related compounds. Because of this and the fact that dibenzothiophenes are particularly difficult to desulfurize by conventional methods, new methodology that can efficiently perform this reaction are of great interest. Examination of the literature dealing with the desulfurization of dibenzothiophene shows that numerous synthetic problems remain unsolved and that room for new reagents exists. Some examples of the desulfurization of dibenzothiophene (1) to make biphenyl (2) have been reported, however these reactions involve long reaction times [6,7], high temperatures [8–10], complex reagents [11] or low yields [16]. In addition there have been very few examples of the desulfurization of dibenzothiophene sulfoxide (3) [17,18], and dibenzothiophene sulfone (4) [10,19–21] as S-oxidized derivatives of this ring system. In fact, both lithium and sodium [10] have been used to effect sulfur extrusions from dibenzothiophene. However, in both cases low yields occurred unless high temperatures were used. The high temperatures required that the high boiling point solvent, tetradecane, be used. The removal of high boiling point solvents from reaction mixtures can be difficult. The generation of a method which can afford high sulfur extrusion yields, while still using a solvent which can be removed by rotary evaporation, would be of great benefit. In this manuscript we apply our previous work using lithium in combination with sodium as an efficient method for the desulfurization of heterocycles [22,23].
source: www.mdpi.com/1420-3049/15/3/1265/pdf
///////
Jean invites you to view his LinkedIn profile (www.linkedin.com/in/jeansteinhardtresearch), and accepts invitations to join your LinkedIn network.
No comments:
Post a Comment