Sulfur origin

If you mix sulfur and iron filings in a certain proportion and then heat the mixture, you can see a red glow spread through the mixture. After it cools, the black solid lump which has been produced, even if crushed into a powder, does not dissolve in carbon disulfide and is not attracted by a magnet. The material has a new set of properties it is a compound, called iron(II) sulfide. It has a definite composition, and if, for example, you had mixed more iron with the sulfur originally, some iron(II) sulfide and some leftover iron would have resulted. The extra iron would not have become part of the compound. 

Burning coal produces sulfur oxides. Where did the sulfur originate ... 

The high-boiling distillates, such as the atmospheric and vacuum gas oils, are not usually produced as a refinery product but merely serve as feedstocks to other processes for conversion to lower-boiling materials. For example, gas oils can be desulfurized to remove more than 80% of the sulfur originally in the gas oil with some conversion of the gas oil to lower-boiling materials (Table 6-11). The treated gas oil (which has a reduced carbon residue as well as lower sulfur and nitrogen contents relative to the untreated material) can then be converted to lower-boiling products in, say, a catalytic cracker where an improved catalyst life and volumetric yield may be noted. 

In a coal desulfurization study, Narayan et al. (50) were able to extract an appreciable amount of elemental sulfur (36% of total sulfur) with perchloroethylene at 120 °C from weathered coal, but not from fresh coal. Hackley et al. (51) determined the isotopic composition of elemental sulfur extracted by perchloroethylene and obtained results consistent with the interpretation that the elemental sulfur originates from the oxidation of pyrite. 

Bayer, Pan, and Kazmaier (7) proposed that labile sulfur originates from cysteinyl residues by a p-elimination reaction in the presence of... 

Bayer et al. (7) succeeded in reconstituting clostridial ferredoxin from a, a -dipyridyl-treated apoferredoxin in the presence of ferrous ion without the presence of a labile sulfur source. Based on this observation, they proposed that labile sulfur originates from cysteinyl residues in the presence of iron. Contrary to their finding, Rabinowitz and his coworkers (21, 33) demonstrated that the reconstitution of clostridial ferredoxin from mersaryl-, a, a -dipyridyl-, and trichloroacetic acid-treated apo-ferredoxins absolutely requires the addition of hydrogen sulfide. Consequently, they concluded that cysteine is not the source of labile sulfur . 

Habashi and Torres-Acuna (H6) described a process that involved th direct recovery of copper and elemental sulfur by anodic dissolution o copper (I) sulfide (white metal). The white metal produced from th (jopper matte analyzed 77.85% Cu and 19.20% S. A closed vessel wa used to prevent the evaporation of the copper (II) sulfate acidified wit sulfuric acid electrolyte. The electrolysis was carried out at room tempera ture. The sulfur originally present in the white metal went into the slim as pure elemental sulfur. The elimination of the converting and polin, steps in the conventional copper smelting and refining process can b realized by use of this technique. 

Sulfur isotopes are more fruitful in resolving the relative contributions of reduction or oxidation processes. For example, in the Peace River area of Alberta, Canada, sulfur and sulfate are deposited on the tops of peat occurrences. At depths of 80 cm and lower, pyrites are found with 6 S values typically around —24%o. Above 80 cm depth, elemental sulfur begins to dominate and has values in the range —28 to —30%o. The sulfate deposits very close to the smrface have values near —33%o. The isotopic data are consistent with the preferential reaction of S during sulfide oxidation. This, coupled with the occurrence of the more oxidised species near the surface, leads to the conclusion that the elemental sulfur originated from deeper sulfide sources (Krouse, 1979). 

This sulfur, originating from the gasoline as well as from tlie oil additives, reaches tlie catalyst mainly as SO2 under nonnal operation conditions, e.g.(2). 

In regions of high volcanic activity, the element sulfur can he found in pure form. Therefore, no one discovered sulfur ancient people were very familiar with it. The phrase fire and brimstone refers to sulfur. Originally, brimstone meant the gum of the gopher tree, but later the term brimstone was used to refer to anything inflammable, such as sulfur. In fact, medieval alchemists used the word sulfur to refer to any substance that could undergo combustion. (An alternate form of spelling sulfur is sulphur.)... 

The distribution of sulfur (originally added as CS2) in xanthated crumb can be determined by UV absorption spectrophotometry. Hovenkamp [154] and others have used this technique to follow the course of the xanthate reaction. Typical results are outlined in Figure 10.56, which summarizes the relative change in concentration of reactants and products. The CS2 concentration continually decreases and sulfide and by-products increase as the reaction proceeds. The xanthate concentration passes through a maximum and then begins to decrease, while the by-product (trithiocarbonate) continues to increase after the CS2 has been consumed. 

The Eschka method for the determination of sulfur originated more than 100 years ago and has been accepted as a standard method in several conntries. The method has distinct advantages in that the equipment is relatively simple and only the more convenient analytical techniques are employed. 

The high gas yield is due to the relatively long residence times of the products in the reactor by virtue of which thermal decomposition occurs to yield gaseous products that are, in actual fact, a secondary product insofar as they are not formed from the coal. The majority of the sulfur originally in the coal occurs in the char. 

The liquid products are filtered to remove particulate matter and then hydrotreated (370°C-425°C [700°F-800°F] 1750-2500 psi hydrogen) to produce a synthetic crude oil (Table 19.1) from whieh the majority (90%) of the nitrogen, oxygen, and sulfur have been removed. As already noted for the Lurgi-Ruhrgas process, the majority of the sulfur originally in the coal occurs in the char and, therefore, combustion of the char may be an environmental problem unless there is some effort made to install stack gas cleaning equipment. 

In the burning process, sulfur—originally present in the fuel in the form of organic compounds—is oxidized first to sulfur dioxide, which reacts further with the caibonate that is present and additional oxygen of the air to yield calcium sulfate (anhydrite, CaS04) ... 

Sulfur Recovery From Gases - Recovered sulfur accounts for over 60% of the total world production of elemental sulfur. Most of the recovered sulfur originates from the processing of fossil hydrocarbons, especially natural gas, oil, and coal. In natural gas, sulfur is mainly in the form of hydrogen sulfide, but in oil and coal it is also present as organic compounds such as mercaptans and as sulfides, disulfides, and heterocyclic compounds. 

Degradation of nickel-cermet anodes due to the adsorption of sulfur originated from H2S in fuels. An initial drop in performance after introducing H2S is maintained without further degradation. After switching back to the... 

Aluminum is produced by the electrolysis of alumina dissolved in cryolite-based melts. The electrolyte also contains some impurities, that is, iron, silicon, phosphorus, sulfur, and so on [1], The impurities are introduced into the electrolyte with the alumina or fluoride salts or they originate from the carbon anodes. In the Hall-Heroult process we know that sulfur originates as sulfur in the anode carbon (1-5 wt% S) plus some sulfur contained in the alumina and in the aluminum fluoride. 

Sulfur originates mainly from two sources. Petroleum coke used in the production of carbon anodes contains 0.7-3.5 wt% sulfur (cokes with higher sulfur contents are usually blended with low-sulfur cokes). Cryolite and aluminum fluoride also contain sulfur, mainly as sulfate (up to 1 wt%). The chemistry of sulfur in carbon anodes is not fully understood, especially its influence on the electrolysis parameters. Since the sulfur content in the crude oil used in the production of petroleum coke tends to increase with time, the effect of the sulfur content on the carbon consumption (CC) and the current efficiency (CE) was studied in the present work. 

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