Sulfur components

A new route to 2//-thiopyrans has been found in the cyclocondensation of thioenolates with a./J-unsaturated carbonyl compounds. The starting sulfur component can be methyl thiol-thione-ethanoate (90BSF446) or a /3-thienol-aldehyde (90ZC247) as shown by Eqs. (1) and (2), respectively. 

Catalyst Poisons. It is well known that sulfur, chlorine, etc. are strong poisons for nickel catalyst. Chlorine was not detectable in the synthesis gas downstream of the Rectisol in the SASOL plant. The total sulfur content of this gas—in the form of H2S, COS, and organic sulfur components—averaged 0.08 mg/m3 with maximum values of 0.2 mg total sulfur/m3. 

Mass absorption increases strongly with the atomic number Z. For the 14.4 keV radiation of Fe, the coefficient follows approximately the relation k. 0.003 from oxygen to krypton. Therefore, organic solvents containing sulfur or chlorine are virtually opaque to the Mossbauer radiation. The sulfur component of a 2 mm layer of dimethylsulfoxide (DMSO) absorbs 70% of the Mossbauer radiation (/ = 1.1 g cm ) [35]. Even worse is dichloromethane (CH2CI2), having an absorption coefficient of 16.83 cm g. A layer of 0.1 g cm , which is only 0.75 mm thick (p = 1.33 g cm ), absorbs about 82% of 14.4 keV radiation. For the same reason, chlorinated polymers (PVC) or glass should not be used for... 

Tressl, R., Gruenewald. K. G., Kamperschroer, H., Silwar, R., Formation of pyrroles and aroma contributing sulfur components in malt and roasted coffee, Prog. Food Nutr. Sci., 5, 71, 1981. 

Yoshikawa, O. Ishii, Y. Koizumi, K., et al., Enhancement and Stabilization of Desulfurization Activity of Rhodococcus Erythropolis KA2-5-1 by Feeding Ethanol and Sulfur Components. Journal of Bioscience and Bioengineering, 2002. 94(5) pp. 447 152. 

The release of odorous components (i.e., the water-air mass transfer aspects) is dealt with in Chapter 4, and the behavior of sulfur (hydrogen sulfide) was, in this respect, exemplified. Figure 4.4 gives not just an understanding of the release phenomena but also an overall view of the pathways and sinks of sulfur components under sewer conditions. 

Sulfate is typically found in all types of wastewater in concentrations greater than 5-15 gS nr i.e., in concentrations that are not limiting for sulfide formation in relatively thin biofilms (Nielsen and Hvitved-Jacobsen, 1988). In sewer sediments, however, where sulfate may penetrate the deeper sediment layers, the potential for sulfate reduction may increase with increasing sulfate concentration in the bulk water phase. Under specific conditions, e.g., in the case of industrial wastewater, it is important that oxidized sulfur components (e.g., thiosulfate and sulfite) other than sulfate may act as sulfur sources for sulfate-reducing bacteria (Nielsen, 1991). 

TABLE 6.6. Integrated Aerobic and Anaerobic Process Model Concept for Transformations of Organic Matter and Sulfur Components of Wastewater in Sewers. Symbols of Components and Parameters are Defined in Tables 6.5, 6.7 and 6.8. Symbols Used are Given in Appendix A. 

As was pointed out earlier, the concentration of sulfur trioxide found in the combustion gases of flames, though small, is greater than would be expected from equilibrium calculations. Indeed, this same phenomenon exists in large combustors, such as furnaces, in which there is a sulfur component in the fuel used. The equilibrium represented by Eq. (8.94)... 

There are many sulfur components in meteorites which may occur in all possible valence states (—2 to +6). TroUite is the most abundant sulfur compound of iron meteorites and has a relatively constant S-isotope composition (recall... 

The sulfur components ethyl S-(+)-2-methylbutanoate and dimethyl trisulfide (with 0.006 and 0.01 pg/L odour thresholds in water, respectively) were reported as impact-flavour compounds in fresh Hawaiian pineapple essence prepared by solvent extraction. The major volatile components were methyl and ethyl esters [59]. 

Complex II. The succinate dehydrogenase complex, or complex IF, contains a non-haem iron-sulfur component and utilises the electron acceptor FAD to effect the transfer of electrons from FADH2 to coenzyme Q. Inhibitors of succinate dehydrogenase are specific basidio-mycete fungicides, with uses against smuts, bunts, and Rhizoctonia spp. (Figure 4.21). 

SO2 components of the process gas stream. None, however, directly attack the problem of removal of other sulfur values in the gas such as CS2, COS and entrained sulfur mist. These sulfur components can easily exceed 1% of the total sulfur feed and failure to remove them from the process stream can frustrate any attempt to achieve 99%+ recovery even when the Claus reactants, H2S and SO2, have been reduced to low ppm levels. 

More than 70 individual sulfur species were further identified by gas chromatography-atomic emission detection (GC-AED) and by gas chromatography-mass spectroscopy (GC-MS) (12). Figure 5 illustrates the composition of the sulfur components of the gas oil. The major components are individually identified on the figure. It can be seen that alkylbenzothio-phenes and dibenzothiophenes are the major components. The size of the alkyl substituents ranges up to 16 carbons on benzothiophene and up to 7 carbons on dibenzothiophene. 

Table I shows that, upon distillation of a Kuwait crude into several fractions, sulfur components concentrate mostly in the resid fraction. Upon hydrotreating each fraction at fixed reactor conditions, the resid sulfur is more difficult to remove than the gasoline sulfur or the gas oil sulfur.

Certain types of catalyst uranium oxide and chromium oxide may be used as a promoter. This is reported to give a higher resistance to catalyst poisoning by sulfur components and a lower tendency to form carbon deposits. 

A Tracor Northern quantitative energy-dispersive X-ray analysis system with solid-state detectors was used for the electron microprobe measurements. The method is based on electron microbeam point analyses on a maceral level (18, 19) The emitted characteristic X-ray fluorescence radiation is used to quantify sulfur. Other elements of interest, such as iron and calcium, are monitored simultaneously to ensure that only the organic sulfur component is characterized. The measured... 

As mentioned above, the profiles in Figure 8.4 also indicate the presence of an additional low-sulfur component (arrow) in the alcohol-fed animals. This additional component has an apparent relative molecular mass of 70,000. 

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