Sulfur impurity

Naphthenic acids are viscous hquids, with phenohc and sulfur impurities present that are largely responsible for their characteristic odor. Their colors range from pale yeUow to dark amber. An odor develops upon storage of the refined acids. Naphthenic acids have wide boiling point ranges at high temperatures (250—350°C). They are completely soluble in organic solvents and oils but are insoluble (<50 mg/L) in water. Commercial naphthenic acids are available in... 

The acid wash test consists of shaking a mixture of 96% sulfuric acid with benzene and comparing the color of the (lower) acid layer with a set of color standards. Other quaUtative tests include those for SO2 and H2S determination. The copper strip corrosion test indicates the presence of acidic or corrosive sulfur impurities. The test for thiophene is colorimetric. 

Pure carbon disulfide is a clear, colorless Hquid with a deHcate etherHke odor. A faint yellow color slowly develops upon exposure to sunlight. Low-grade commercial carbon disulfide may display some color and may have a strong, foul odor because of sulfurous impurities. Carbon disulfide is slightly miscible with water, but it is a good solvent for many organic compounds. Thermodynamic constants (1), vapor pressure (1,2), spectral transmission (3,4), and other properties (1,2,5—7) of carbon disulfide have been deterrnined. Principal properties are Hsted in Table 1. 

Consider the oil-recycling plant shown in Fig. 3.16. In this plant, two types of waste oil are handled gas oil and lube oil. The two streams are first deashed and demetallized. Next, atmospheric distillation is used to obtain light gases, gas oil, and a heavy product. The heavy product is distilled under vacuum to yield lube oil. Both the gas oil and the lube oil should be further processed to attain desired properties. The gas oil is steam stripped to remove light and sulfur impurities, then hydrotreated. The lube oil is dewaxed/deasphalted using solvent extraction followed by steam stripping. 

Over the past decades, advances have been made that reduce environmental impacts of coal burning in large plants. Some arc standard and others experimental. Limestone (mainly calcium carbonate) scrubber smokestacks react with the emitted sulfates from the combustion and contain the chemical products, thereby reducing the release of SO., into the atmosphere by a large factor (of ten or more). Pulverization of coal can also allow for the mechanical separation of some sulfur impurities, notably those in the form of pyrites, prior to combustion. Currently deployed—with more advanced versions in the development stage—are various t yies of fluidized bed reactors, which use coal fuel in a pulverized form, mixed with pulverized limestone or dolomite in a high temperature furnace. This technique reduces sulfate release considerably. There are... 

The production of synthesis gas from natural gas and coal is the basis of the 33 000000 tpa methanol production and is also used in the production of ammonia. After removal of sulfur impurities, methane and water are reacted over a nickel oxide on calcium aluminate catalyst at 730 °C and 30 bar pressure. The reaction is highly endothermic (210 kJmol ) (Equation 6.6). 

The combustion products from sulfur Impurities In coal are particularly damaging to the environment. In humans, prolonged exposure to sulfur dioxide diminishes lung capacity and aggravates respiratory problems such as asthma, bronchitis, and emphysema. Concentrations as low as 0.15 ppm can incapacitate persons with these diseases, and at about 5 ppm everyone experiences breathing difficulties. In 1952 a particularly serious episode of SO2 pollution In London caused approximately 4000 deaths over several days. 

C05-0119. Explain in your own words how sulfur impurities in coal can lead to acid rain. Use balanced equations... 

HD in the body is very slow, and repeated exposures produce a cumulative effect. Its toxic hazard is high for inhalation, ingestion, and skin and eye absorption, but the most common acute hazard is from liquid contact with eyes or skin. Agent HD is distilled H, it has been purified by washing and vacuum distillation to reduce sulfur impurities. Agent H is a mixture of 70% bis-(2-chloroethyl) sulfide and 30% sulfur impurities produced by unstable Levinstein process. 

The by-product, representing a relatively reduced form of sulfur, is a reasonable model for the sulfur impurities in the synthesis gas obtained from sulfur-rich coal. This sodium sulfide test of sulfur resistance of water gas shift catalyst systems generated in basic solutions is a very severe test since the quantities of sulfur involved are much larger than those likely to be found in synthesis gas made from any sulfur-rich coals. 

Gasifiers typically produce contaminants that need to be removed before entering the fuel cell anode. These contaminants include H2S, COS, NH3, HCN, particulate, and tars, oils, and phenols. The contaminant levels are dependent upon both the fuel composition and the gasifier employed. There are two families of cleanup that can be utilized to remove the sulfur impurities hot and cold gas cleanup systems. The cold gas cleanup technology is commercial, has been proven over many years, and provides the system designer with several choices. The hot gas cleanup technology is still developmental and would likely need to be joined with low-temperature cleanup systems to remove the non-sulfur impurities in a fuel cell system. For example, tars, oils, phenols, and ammonia could all be removed in a low-temperature water quench followed by gas reheat. 

Matsuzaki and Yasuda did not observe an obvious dependence of the time needed for the influence of the sulfur impurity to saturate with respect to sulfur concentration when H2S concentration was in the range of 2 to 15 ppm at 1000°C. Such dependence, however, was observed at lower temperatures (e.g., 750°C) in fuels with 0.1 to 10 ppm H2S by Waldbillig et al. [65] and Sprenkle et al. [73] on anode-supported cells, as shown in Figure 2.26. 

Surface polymerization of thiophenes was fou d to be affected by both surface impurities and substituent groups on the thiophene ring. The reactions of thiophene on a Ni(lll) surface with sulfur impurities was examined [11]. The sulfur inhibited the polymerization so that the only reactions observed were desorption of thiophene with a small... 

Chemical Agent H Levinstein mustard (CAS 471-03-4) is a mixture of 70 percent bis (2-chloroethyl) sulfide and 30 percent sulfur impurities produced by the Levinstein process and is a blister agent. 

Hydrogen sulfide in manufactured gases may range from approximately 2.30 g/m (100 gr/100 ft ) in blue and carbureted water gas to sever hundred grains in coal- and coke-oven gases. Another important sulfur impurity is carbon disulfide, which may be present in amounts varying from 0.007 to 0.07 percent by volume. Smaller amounts of carbon oj sulfide, mercaptans, and thiophene may be found. However, most of the impurities are removed during the purification process and either do not exist in the finished product or are present in only trace amounts. 

It is used for the production (thermal reduction) of other metals, such as zinc, iron, titanium, zirconium, and nickel. For instance, because of its strong electropositive nature, magnesium can desulfurize molten iron when it combines with the sulfur impurities in the iron to produce high-grade metallic iron plus MgS. 

It is used to remove carbon and sulfur impurities during the processing of iron, producing a higher-grade iron for use in the manufacture of steel. It is also used as a reducing agent in the preparation of several other important metals. 

Sulfur impurities can be detrimental to nickel deposits. Specifically, an increase in sulfur couteut is known to reduce the fracture resistance of electroformed nickel. Since sulfur has a direct influence on the properties of electrodeposited nickel, if no other impurities are present in the deposit, hardness by itself can be used as an indicator of sulfur impurity content. 

The catalytic hydrogenation of petroleum fractions to remove sulfur impurities. Hydrogen is very soluble in the liquid high pressure is used while the impurity is present in the liquid in low concentration. All these factors tend to lead to extreme 2 (excess of A). 

Fig. 4.48 Composition of the first three atomic layers of Pt-Rh alloys, thermally equilibrated at 700°C, which contain about 50 p.p.m. of sulfur impurity.

Fig. 4.49 Composition depth profiles of the (001) plane of two Pt-44.8 at.% Rh alloys, one containing sulfur impurity and one not. Note the reversal of the enriched species, in both the top and the second layers.

Fig. 4.50 Concentration of the top surface layer in surface segregation of Pt-Rh alloys obtained by different surface analytical techniques. Data points indicated with TRA are from Tsong, Ren Ahmad, LN is from Langenveld Niemants-verdriet, WN are from Williams Nason, DN is from van Deft Nieuwenhuys and HW is from Holloway Williams. Data points AT are from Ahmad Tsong, obtained with samples containing 50 p.p.m. of sulfur impurities. See references 234 and 240 for the origin of the data.

Alkylation of benzene with ethylene gives ethylbenzene,283,284,308,309 which is the major source of styrene produced by catalytic dehydrogenation. High benzene ethylene ratios are applied in all industrial processes to minimize polyethylation. Polyethylbenzenes formed are recycled and transalkylated with benzene. Yields better than 98% are usually attained. Reactants free of sulfur impurities and water must be used. 

Purification and Refinement. The purification and refinement operations can be batch or continuous. The raw blue is crushed and ground, slurried in warm water, then filtered and washed to remove the sulfoxides. Reslurrying and wet grinding release the sulfurous impurities and reduce the ultramarine particle size, often to 0.1-10.0 pm. The impurities are floated off by boiling or cold froth flotation. 

Most phosphorus and sulfur impurities are removed in a basic oxygen furnace, but the purified metal still contains about 3 percent carbon. For the production of iron, this carbon is desirable. Iron atoms are relatively large, and when they pack together, small voids are created between atoms, as shown in... 

The terpenes used were mainly /3-pinene fractions provided by DRT (Soci6td des Derives Rdsiniques et Terpeniques, Vielle-S Girons) and, for certain experiments a turpentine oil containing the main three terpenes a-pinene, /3-pinene, and A -carene. The /3-pinene fractions contained 80-90% /3-pinene, 2% a-pinene, 4-5% myrcene, 2-3% dipentene and 700-1500 ppm S. GC-MS analyses showed that sulfur impurities were composed of alkyl and alkenyl sulfides (mainly dimethyl sulfide), alkyl and alkenyl disulfides (mainly dimethyl disulfide), trisulfides, thiophene and alkylthiophenes (methyl, dimethyl, acetyl and tertiobutyl). 

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