Desulfurization selective oxidation

Desulfurization processes are absolutely necessary for producing clean fuels. Possible strategies to realize ultradeep suffiirization currently include adsorption, extraction, oxidation, and bioprocesses. Oxidative desulfurization (ODS) combined with extraction is considered one of the most promising of these processes [13]. Ultradeep desulfurization of diesel by selective oxidation with amphiphilic catalyst assembled in emulsion droplets has given results where the sulfur level of desulfurized diesel can be lowered from 500 ppm to about 0.1 ppm without changing the properties of the diesel [12]. 

Although the selective oxidation of coal has been extensively studied (31-33, surprisingly little has been reported about sulfur species in the oxidation products. Even less is known about the distribution of organic sulfur species between different coal macerals despite the fact that this information is important for the development of any future desulfurization technology. 

Wu, X.X., Schwartz, V., Overbury, S.H., and Armstrong, T.R. Desulfurization of gaseous fuels using activated carbons as catalysts for the selective oxidation of hydrogen sulfide. Energy Fuels, 2005, 19, 1774. 

NG (natural gas, methane) or LPG (propane+butane) reforming -Methane has 25% wt of hydrogen water has only 11% however, gaseous fuels are not good for storage and transportation. Natural gas is most used today in low-temperature fuel cells (PEFC and PAFC) it is first desulfurized (from previously added safety odorants), then steam-reformed (yields 10% CO), afterwards shift-converted (reduces CO to 1%), and (only for PEFC) finally selectively oxidized (to <10 ppm CO). 

Conditions for the reductive desulfurization of 3,6-bis(methylthio)pyridazine (108), (Scheme 70) with Raney nickel have been developed as part of a synthetic approach to 4- or 4,5-disubstituted pyridazines based on Diels-Alder reactions of 3,6-bismethylthio-l,2,4,5-tetrazine. Selective oxidation of (108) can give the monosulfoxide, bis(sulfoxide), and bis(sulfone) depending on the conditions used, and the bis(sulfone) was susceptible to nucleophilic displacement of one sulfonyl group. These studies were limited to the symmetrical substrate (108) <88JOCi4i5>. 

Evaluate alternate approaches for the major catalytic components (e.g., desulfurizer, reformer, shift reactor and selective oxidation reactor). 

Beside the above-mentioned catalysts used for the production processes of ammonia, hydrogen, urea and other important inorganic chemicals, some other catalysts might be used during some accessorial processes. They are N2 production catalysts, CO selective oxidation catalysts, sulfur recovery catalysts, CO2 dehydrogenation catalysts, molecular sieve desiccants and de-poison catalysts such as desulfurization, dechlorination, and dearsenization, etc. 

Collins, F.M. Lucy, A.R. Sharp, C. Oxidative desulphurization of oils via hydrogen peroxide and heteiopolyanioncatalysts,J.Afo/. Catal. A Chemical, 1997, 777, 397-403. Dolbear, G.E. Skov, E.R. Selective oxidation as a route to petroleum desulfurization. Prep. Div. Pet. Chem., jAmerican Chemical Society, 219 National Meeting, San Francisco, CA, March 26-31,2000 375-378. 

Chapados, D. Desulfurization by Selective Oxidation and Extraction of Sulfur-Containing Compounds to Economically Achieve Ultra-Low Proposed Diesel Fuel Sulfur Requirements, Paper presented at the 2000 NPRA Annual Meeting. 

Dolbear, G.E. Skov, E.R. Selective Oxidation as a Route to Petroleum Desulfurization, American Chemical Society National Meeting, San Francisco, March 2000... 

Seeberger, A. Jess, A. (2010). Desulfurization of diesel oil by selective oxidation and extraction of sulfur compounds by ionic liquids-a contribution to a competitive process design. Green Chem., 12,602-608, ISSN 1463-9270. 

Oxidative desulfuration releases active sulfur that binds to, and deactivates, P450 Selective inhibitors Specific inhibitor of lAl Specific inhibitor of 1A2 Specific inhibitor of 2A6 Specific inhibitor of 2C9 Specific inhibitor of 2D1 Specific inhibitor of 2E1... 

Further work at EniTecnologies was conducted with Rhodococcus strains. Rhodococ-cus was selected for its metabolical versatility, easy availability in soils and water, and remarkable solvent tolerance. Its capabilities for catalyzing diverse transformation reactions of crude oils, such as sulfur removal, alkanes and aromatics oxidation and catabolism caught their attention. Hence, genetic tools for the engineering of Rhodococcus strains have been applied to improve its biotransformation performance and its tolerance to certain common contaminants of the crude oil, such as cadmium. The development of active biomolecules led to the isolation and characterization of plasmid vectors and promoters. Strains have been constructed in which the careful over-expression of selected components of the desulfurization pathway leads to the enhancement of the sulfur removal activity in model systems. Rhodococcus, Gordona, and Nocardia were transformed in this way trying to improve their catalytic performance in BDS. In a... 

An interesting synthetic approach to thietanes is the selective desulfurization of cyclic disulfides.The treatment of dithiolanes with a diethyl-aminophosphine results in a ring contraction to thietanes, (Eq. 19). This has been demonstrated with a-lipoic acid, a coenzyme with a dithiolane structure involved in the biological oxidation of pyruvic acid. The reaction is proposed to be initiated by the electrophilic attack of the phosphorus on the ring sulfur atom, resulting in the formation of an acyclic internal phosphonium salt, which by subsequent elimination of a phosphine sulfide, closes to the four-membered ring. °... 

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