Naphtha, Gasoline, and Solvents

Naphtha is the general term that is applied to refined, partly refined, or unrefined low-boiling petroleum products. Naphtha is prepared by any one of several methods, including (1) fractionation of distillates or even crude petroleum, (2) solvent extraction, (3) hydrogenation of distillates, (4) polymerization of unsaturated (olefinic) compounds, and (5) alkylation processes. Naphtha may also be a combination of product sfieams from more than one of these processes. 

The main uses of petroleum naphtha fall into the general areas of (1) precursor to gasoline and other liquid fuels, (2) solvents (diluents) for paints, (3) dry-cleaning solvents, (4) solvents for cutback asphalts, (5) solvents in the rubber industry, and (6) solvents for industrial extraction processes. Turpentine, the older and more conventional solvent for paints has now been replaced almost completely by the cheaper and more abundant petroleum naphtha. 

The term aliphatic naphtha refers to naphtha containing less than 0.1% benzene and with carbon numbers from C3 through Cie. Aromatic naphtha has 

Gasoline varies widely in composition, and even those with the same octane number may be quite different. The variation in aromatics content as well as the variation in the content of normal paraffins, branched paraffins, cyclopentane derivatives, and cyclohexane derivatives all involve characteristics of any one individual crude oil and influence the octane number of a gasoline. 

Automotive gasoline contains 150 or more different chemical compounds and the relative concentrations of the compounds vary considerably, depending on the source of crude oil, refinery process, and product specifications. Typical hydrocarbon constituents are (volume basis) alkanes (4 to 8%), alkenes (2 to 5%), isoalkanes (25 to 40%), cycloalkanes (3 to 7%), cycloalkenes (1 to 4%), and aromatics (20 to 50%). However, these proportions vary greatly. 

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