Sulfur grade

Conversion of heterocyclic aromatic compounds or other aromatic fuel components to paraffins by hydroprocessing can help increase the cetane number of diesel fuel. Fuel paraffins have significantly higher cetane number values than fuel aromatics. For this reason, the cetane number of ultra-low sulfur diesel fuel will typically be one to five numbers greater than higher-sulfur grade fuels. 

Kerosene has essentially the same boiling range distillation as Jet A and is thus of similar composition. The main difference is the presence of sulfur species in kerosene. A low sulfur grade kerosene is produced as well as a regular high sulfur grade. The carbon range is C8-C16 and a typical composition is 70% saturated hydrocarbons, 30% aromatics. C10-C12 are the most abundant alkanes present. 

SI 9. [D ussa] Sulfur grade (xgano-silane crasslinJdng and coupling i ent for rubber. 

In these polymers with the repeating unit -(-R—Sx, x is known as the sulfur grade. The sulfur grade gives the average number of sulfur atoms per repeating unit. 

Bis(2-chloroethyl)-formal, (C1CH2CH20)2CH2, is the halogen compound most often used industrially, and this leads to a sulfur grade of 2. 1,2-Dichloroethane is also used in some cases, and this gives a sulfur grade of 4, and in other cases, a mixture of bis(2-chloroethyl)-formal and 1,2-dichloro-ethane is used (sulfur grade 2.2). 

Table 27-1. Effect of the Sulfur Grade on the Consistency of Organic Polysulfide Polymers...

The properties of the cured polymers depend primarily on the sulfur grade (Table 27-1). In these cases, polymers of high sulfur grades have chains with units of the kind —S — S—S —. Higher sulfur grades can be reduced by treatment with sodium polysulfide. For example, reaction of equimolar quantities of -f-RS4-)-and Na2S4 produces -<-RS3.i> and Na2S4.9. 

Commercial grades of polysulfides are synthesized by using dichloro-ethylene (Thiokol A of the Thiokol Chemical Corp., sulfur grade 4), bis-(2-chloroethyl)-formalin (Thiokol FA, sulfur grade 2), or a mixture of these two compounds (Thiokol ST, sulfur grade 2.2) as the dihalogen compounds. 

The polymer properties depend first and foremost on the sulfur grade of the sample (Table 27-1). A higher sulfur grade gives a better elastomer. 

Monel alloy 405 is a higher sulfur grade in which the sulfur content is increased over that of alloy 400 to improve machinability. Refer to Table 15.3 for the chemical composition. The corrosion resistance of this alloy is essentially the same as alloy 400. 

These insoluble sulfur grades are commonly used with high oil treatment to help prevent dust explosions during mixing in an internal mixer. 

Sulfur grade is used in this application for good dynamic properties. 

Some of the principal forms in which sulfur is intentionally incorporated in fertilizers are as sulfates of calcium, ammonium, potassium, magnesium, and as elemental sulfur. Ammonium sulfate [7783-20-2] normal superphosphate, and sulfuric acid frequendy are incorporated in ammoniation granulation processes. Ammonium phosphate—sulfate is an excellent sulfur-containing fertilizer, and its production seems likely to grow. Some common grades of this product are 12—48—0—5S, 12—12S, and 8—32—8—6.5S. 

Standards for sulfuric acid, ranging from technical-grade through dmg-, food-, and reagent-grade, to electronic-grade are shown in Table 1. The advances in purity represented by these various grades of chemicals are based on the special uses of the chemicals. 

Table 1. Specifications for Various Grades of Sulfuric Acid...

Production. Indium is recovered from fumes, dusts, slags, residues, and alloys from zinc or lead—zinc smelting. The source material itself, a reduction bullion, flue dust, or electrolytic slime intermediate, is leached with sulfuric or hydrochloric acid, the solutions are concentrated, if necessary, and cmde indium is recovered as 99+% metal. This impure indium is then refined to 99.99%, 99.999%, 99.9999%, or higher grades by a variety of classical chemical and electrochemical processes. 

Acid Oxidation. Reactions of lead with acid and alkaUes are varied. Nitric acid, the best solvent for lead, forms lead nitrate acetic acid forms soluble lead acetate in the presence of oxygen sulfuric acid forms insoluble lead sulfate. Sulfuric acid is stored in containers with chemical or acid-grade lead. Lead dissolves slowly in HCl, but in the presence of aqueous alkaUes forms soluble plumbites and plumbates. 

---