Sulfur internal

International Gasoline Rankings - Top 100 Sulfur., International Fuel Quality Center, http //208.72.1.66/UserFiles/file/Misc/ GasolineRanking-May2010.pdf (last accessed 24 December 2010). 

ISO 157 (1996) Coal Determination of Forms of Sulfur, International Standards Organization, Geneva, Switzerland. www.iso.org. 

Topsoe s New Ammonia Process, Topsoe Topics (March 1976) I. Dybkjaer, Fertilizer Nitrogen, British Sulfur International Conference, London (January 1981). 

Benson, J.D. et al. (1991), Effects of gasoline sulfur level on mass exhaust emissions . SAE paper No. 91-2323, International fuels and lubricants meeting, Toronto, Ontario. 

The stmcture of the ketones produced from unsymmetrical internal perfluoroepoxides has been reported (5). The epoxide ring may also be opened by strong protic acids such as fluorosulfonic acid or hydrogen fluoride at elevated temperatures (23—25). The ring opening of HFPO by sulfur trioxide at 150°C has been interpreted as an example of an electrophilic reaction (26) (eq. 3). 

The advent of a large international trade in methanol as a chemical feedstock has prompted additional purchase specifications, depending on the end user. Chlorides, which would be potential contaminants from seawater during ocean transport, are common downstream catalyst poisons likely to be excluded. Limitations on iron and sulfur can similarly be expected. Some users are sensitive to specific by-products for a variety of reasons. Eor example, alkaline compounds neutralize MTBE catalysts, and ethanol causes objectionable propionic acid formation in the carbonylation of methanol to acetic acid. Very high purity methanol is available from reagent vendors for small-scale electronic and pharmaceutical appHcations. 

Process. A typical indirect hydration process is presented in Eigure 1. In the process, propylene reacts with sulfuric acid (>60 wt%) in agitated reactors or absorbers at moderate (0.7—2.8 MPa (100—400 psig)) pressure. The isopropyl sulfate esters form and are maintained in the Hquid state at 20—80°C. Low propylene concentrations, ie, 50 wt %, can be tolerated, but concentrations of 65 wt % or higher are preferred to achieve high alcohol yields. Because the reaction is exothermic, internal cooling coils or external heat exchangers are used to control the temperature. 

Miscellaneous Sulfur Chemicals—United States, Chemical Economics Handbook, 780.4000M-X, Stanford Research Institute International, Menlo Park, Calif., May 1992. 

In 1972, the Agency for International Development (AID) cooperated with the Sulphur Institute to prepare a program to evaluate the feasibihty of using the sulfur surface-bond technique in developing countries. Afterwards AID awarded a contract to Southwest Research Institute to constmct houses in South America and Africa using this technique. Under the contract, about 60 houses have been completed (62). 

Steel tank cats, often lined to minimize iron contamination, are usually employed for high concentrations of sulfuric acid. Bottom outlets or valves are not allowed, nor are internal steam coils. Tank contents must be unloaded via standpipe. Using air pressure to unload is not recommended for safety reasons, but if air pressure is used, gauge pressures should be held at <0.21 MPa (30 psi). 

T. J. Browder in A. I. More, ed., "Making the Most of Sulfuric Acid," Proceedings of The British Sulphur Corporation s Fifth International Conference, British Sulphur Pubhshing, London, Nov. 1981, pp. 183—205. 

NACE Standard PR0294 (latest revision). Design, Fabrication and Inspection of Tanksfor the Storage of Concentrated Sulfuric Fcid and Oleum atFmbient Temperatures, NACE International, Houston, Tex., 1994. 

The Corrosion ofNickel-ContainingFlloys in Sulfuric Fcid and delated Compounds, Corrosion Engineering Bulletin CEB-1, Inco Alloys International, Huntington, W.Va., 1983. 

Sulfuric Acid iu Chemical Economics Handbook, SRI International, Menlo Park, CaHf., Aug. 1995. 

M. C. Manderson and C. D. Cooper, Sulfur 84 International Conference Calgary, Alberta, Canada, June 3—6,1984. 

Stannous Sulfate. Stannous sulfate (tin(Il) sulfate), mol wt 214.75, SnSO, is a white crystalline powder which decomposes above 360°C. Because of internal redox reactions and a residue of acid moisture, the commercial product tends to discolor and degrade at ca 60°C. It is soluble in concentrated sulfuric acid and in water (330 g/L at 25°C). The solubihty in sulfuric acid solutions decreases as the concentration of free sulfuric acid increases. Stannous sulfate can be prepared from the reaction of excess sulfuric acid (specific gravity 1.53) and granulated tin for several days at 100°C until the reaction has ceased. Stannous sulfate is extracted with water and the aqueous solution evaporates in vacuo. Methanol is used to remove excess acid. It is also prepared by reaction of stannous oxide and sulfuric acid and by the direct electrolysis of high grade tin metal in sulfuric acid solutions of moderate strength in cells with anion-exchange membranes (36). 

In fine wool such as that obtained from merino sheep, the cuticle is normally one cell thick (20 x 30 x 0.5 mm, approximate dimensions) and usually constitutes about 10% by weight of the total fiber. Sections of cuticle cells show an internal series of laminations (Figs. 1 and 2) comprising outer sulfur-rich bands known as the exocuticle and inner regions of lower sulfur content called the endocuticle (13). On the exposed surface of cuticle cells, a membrane-like proteinaceous band (epicuticle) and a unique hpid component form a hydrophobic resistant barrier (14). These hpid and protein components are the functional moieties of the fiber surface and are important in fiber protection and textile processing (15). 

The reaction involves two electrons per thionyl chloride [7719-09-7] molecule (40). Also, one of the products, SO2, is a Hquid under the internal pressure of the cell, facihtating a more complete use of the reactant. Finally, no cosolvent is required for the solution, because thionyl chloride is a Hquid having only a modest vapor pressure at room temperature. The electrolyte salt most commonly used is lithium aluminum chloride [14024-11-4] LiAlCl. Initially, the sulfur product is also soluble in the electrolyte, but as the composition changes to a higher SO2 concentration and sulfur [7704-34-9] huA.ds up, a saturation point is reached and the sulfur precipitates. 

Various improvements in the sulfur dioxide reduction processes have been commercialized, including the Canadian International Paper Process (1946) and the Kesting, Persson, and Holst processes. A variation combining both chloride and sulfur dioxide reductant processes was developed and patented by KemaNord AB (47). 

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