Crude distillation fractions, yields

A low temperature cracking (350°C) of the ozonated crude oil raw material initiated by ozonides and sulfoxides leads to a significant increase of distillate fraction yield and a significant decrease in the sulfur content of the products. 

Figure 1.1 illustrates the diversity of products derived from petroleum classified according to their distillation ranges and number of carbon atoms. From one crude to another, the proportions of the recovered fractions vary widely. A good illustration is the gasoline fraction (one of the most economically attractive) a crude from Qatar gives about 37 per cent by volume whereas a Boscan crude oil only yields 4.5%. 

To a mixture of anhyd ethylene glycol (250 mL) and anhyd KF (168 g, 3.0 mol) in a mechanically stirred 1-L flask fitted with a distillation head and a pressure-equalizing addition funnel was added dropwise l-bromopropan-2-one (1 102 g, 0.75 mol) at 160 C. The crude product 2 distilled from the mixture over a 70— 120 C boiling point range. The crude distillate was dried (K2C03) and then fractionally distilled yield 9.00 g (20%) bp 75-77 "C/760 Torr. 

In a 3-I. round-bottom flask, a hydrobromic add solution is made by the sulfur dioxide reduction of 480 g. of bromine in the presence of 510 g. of ice water or a mixture is made of 1000 g. of aqueous 48 per cent hydrobromic acid and 300 g. of concentrated su. furic acid. To this are added 385 cc. of aqueous allyl alcohol, which, according to bromine titration, contain 233 g. of pure allyl alcohol. The 3-I. round-bottom flask is fitted with a mechanical stirrer (Fig. 1, p. 4, see also Notes), separatory funnel, and an efficient condenser set for downward distillation. Stirring is started and 300 g. of concentrated sulfuric add are added gradually through the separatory funnel to the warm solution. The allyl bromide distils over completely in about one-half to one hour. The crude allyl bromide is washed with dilute sodium carbonate solution, is dried over calcium chloride and is distilled. The yield of product boiling at 60-72° from a number of experiments varies from 443 to 465 g. (92-96 per cent theory). A small high-boiling fraction is also obtained and examination has shown this to consist of propylene bromide. 

Cognate preparation. 1-Phenylethanol. Use 10.4g (11.5ml, 0.1 mol) of styrene, and carry out the oxymercuration and reduction as described above. The yield of recovered mercury is 17.5 g (87%), and traces continue to separate during the work-up procedure. Distil the final crude product under reduced pressure and collect the 1-phenylethanol at 110-115 °C/25mmHg. Towards the end of the distillation the decomposition of residual organo-mercurial compounds ensues, and co-distillation of mercury contaminates the product collect the contaminated fraction separately. The first fraction, yield 6.2 g (51%), is 92 per cent pure by g.l.c. (retention time 5.33 minutes) the impurity is mainly styrene (tR 2.16 minutes). The mercury-contaminated fraction (3.0 g, 25%) is 85 per cent pure by g.l.c. 

The residuum fraction of a full range crude is that fraction remaining after all of the distillate is taken overhead. As noted in Figure 1, this residuum fraction or resid may be obtained with either atmospheric or vacuum fractionation, yielding either long or short resid. 

In order to obtain pure aromatics, crude reformate is extracted to separate the aromatics from unreacted paraffins and cycloparaffins. The aromatics are, in turn, separated by simple fractional distillation to yield high purity benzene, toluene, xylenes, and C9 aromatics. 

One metric ton of crude tall oil yields about 350 kg of rosin, 300 kg of fatty acids, and 300 kg of head and pitch fractions. For each metric ton of pulp produced, northern pines yield about 50 kg of tall oil, and the southern pines yield about 125 kg. The U.S. capacity for fractional distillation of tall oil is nearly one million metric tons per year. 

The kerosene fraction is essentially a distillation fraction of petroleum. The quantity and quality of the kerosene vary with the type of crude oil some crude oils yield excellent kerosene but others produce kerosene that requires substantial refining. Kerosene is a very stable product, and additives are not required to improve the quality. Apart from the removal of excessive quantities of aromatics, kerosene fractions may need only a lye (alkali) wash if hydrogen sulfide is present. 

Together with benzene and naphthalene two other hydrocarbons are obtained from coal tar though in much smaller amounts. They are anthracene and phenanthrene, both of which have the formula CuHjo. Anthracene together with phenanthrene is present in the coal tar distillate which boils above 270°. The yield of anthracene is about 0.25 to 0.45 per cent of the tar. The crude distillate is purified by a second distillation and separated into two fractions (i) A product known as 50 per cent anthracene which is crystalline and still contains phenanthrene. (2) A less volatile non-crystalline oil known as anthracene oil. The 50 per cent anthracene is largely used, just as it is without further purification, in the preparation of alizarin, itsmost important derivative. To obtain pure anthracene from the crude 50 per cent product it is first redistilled after addition of potassium carbonate which forms a non-volatile compound with a constituent known as carbazole. 

The aromatic content of the oil was 33 per cent (10) as measured by carbon-13 nmr. Crude distillation at atmospheric pressure yielded a major fraction (42 per cent) which boiled in the range 190-350°C and unlike the crude product was completely miscible with diesel fuel. A duplicate of this seven run series was carried out and it yielded very similar results. Results for shorter series in which different amounts of catalyst were added will be reported elsewhere (11). 

A stirred mixture of cyclopropyltriphenylphosphonium bromide (19.25 g, 50.5 mmol) in THF (180 mL) was treated with PhLi (2.32 M in benzene, 21.5 mL, 50 mmol) under an Nj atmosphere. The mixture was stirred for about 45 min then refluxed for 15 min. To the red-brown solution was added dropwise over a 20 min period freshly distilled cyclohexanone (4.91 g, 50 mmol) and stirring with mild heating was continued for 24 h. The light tan mixture was coneentrated and then short-path distilled in vacuo, followed by fractional distillation of the crude distillate yield 2.87 g (47%) > 98% pure (as determined by GC) bp 118-119"C/144Torr. 

Kerosene was first manufactured in the 1850s from coal tar, hence the name coal oil as often applied to kerosene, but petroleum became the major source after 1859. From that time, the kerosene fraction was, and has remained, a distillation fraction of petroleum. However, the quantity and quality vary with the type of crude oil, and although some crude oils yield excellent kerosene quite simply, others produce kerosene that requires substantial refining. 

Catalytic hydrogenation of crude oils also is a proved means of reducing the sulfur and metallic content and increasing the yield of distillate fractions. The process operates at 430-450 C and at 500-1,000 psig, using hydrogen gas for recycle over the catalyst at a rate of 2,500-10,000 cu ft per bbl of charge. 

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