Freezing point naphtha

When naphtha or naphthenic gasoline fractions are catalytically reformed, they usually yield a Cx aromatics stream that is comprised of mixed xylenes and ethylbenzene. It is possible to separate the ethylbenzene and o-xylene by fractionation. It is uneconomic to separate the m- and p-xylenes in this manner because of the closeness of their boiling points. To accomplish the separation, a Werner-type complex for selective absoiption of p-xylene from the feed mixture may be used. Or, because of the widely different freezing points of the two xylene isomers, a process of fractional crystallization may be used. To boost the p-xylene yield, die filtrate from the crystallization step can be catalytically isomerized. 

Ethylbenzene is always present in crude xylene and in solvent-naphtha. Since the boiling point of ethylbenzene (136°C) is identical with the boiling point of p- xylene, the two are difficult to separate. It is possible to do so by cooling, as the freezing point of ethylbenzene is -94.9%. 

Once the synthetic crude oils from coal and oil shale have been upgraded and the heavy ends converted to lighter distillates, further refining by existing processes need not be covered in detail except to note the essential character of the products. The paraffinic syncrude from oil shale yields middle distillates which are excellent jet and diesel fuel stocks. The principal requirements are removal of nitrogen to the extent necessary for good thermal stability of the fuels and adjustment of cut points to meet required pour or freeze points, limited by the presence of waxy straight-chain paraffins. The heavy naphtha from shale oil can be further hydrotreated and catalytically reformed to acceptable octane number, but with considerable loss of volume because of the only moderate content of cyclic hydrocarbons, typically 45-50%. On the other... 

An indication of naphtha composition may also be obtained from the determination of aniline point (ASTM D-1012, IP 2), freezing point (ASTM D-852, ASTM D-1015, ASTM D-1493) (Fig. 4.2), cloud point (ASTM D-2500) (Fig. 4.3), and solidification point (ASTM D-1493). And, although refinery treatment should ensure no alkalinity and acidity (ASTM D-847, ASTM D-1093, ASTM D-1613, ASTM D-2896, IP 1) and no olefins present, the relevant tests using bromine number (ASTM D-875, ASTM D-1159, IP 130), bromine index (ASTM D-2710), and flame ionization absorption (ASTM D-1319, IP 156) are necessary to ensure low levels (at the maximum) of hydrogen sulfide (ASTM D-853) as well as the sulfur compounds in general (ASTM D-130, ASTM D-849, ASTM D-1266, ASTM D-2324, ASTM D-3120, ASTM D-4045, ASTM D-6212, IP 107, IP 154) and especially corrosive sulfur compounds such as are determined by the Doctor test method (ASTM D-4952, IP 30). 

Ethyl-Naphtha Coal Tar — (i) Chemical Designations — Synonyms Mixture of benzene, toluene, and xylenes Chemical Formula Not applicable (ii) Observable Characteristics — Physical State (as shipped) Liquid Color Colorless to pale yellow Odor Like benzene, toluene, and xylene (iii) Physical and Chemical Properties — Physical State at 15 C and 1 atm Liquid Molecular Weight Not pertinent Boiling Point at I atm 200 - 500, 93 - 260, 366 - 533 Freezing Point Not pertinent Critical Temperature Not pertinent Critical Pressure 794, 54, 5.47 Specific Gravity 0.86 - 0.88 at 20°C (liquid) Vapor (Gas) Specific Gravity Data not available Ratio of Specific Heats of Vapor ((3as) (est.)... 

Jet fuel is kerosene-based aviation fuel. It is medium distillate used for aviation turbine power units and usually has the same distillation characteristics and flash point as kerosene. Jet fuels are manufactured predominately from straight-run kerosene or kerosene-naphtha blends in the case of wide cut fuels that are produced from the atmospheric distillation of crude oil. Jet fuels are similar in gross composition, with many of the differences in them attributable to additives designed to control some fuel parameters such as freeze and pour point characteristics. For example, the chromatogram (Figure 27.4) of a commercial jet fuel (Jet A) is dominated by GC-resolved n-alkanes in a narrow range of n-C-j to n-Cig with maximum being around n-Ci. The UCM is well dehned. 

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