Petroleum fractions, native

Self-generated surfactants (produced from fossil fuels by a chem-ical/physical process) or natural surfactants (exiting in fossil fuels) are derived from the inherent organic acids and replaceable acidic protons which are present in crude oils or bitumens (e.g., mercaptans). Yen and Farmanian (2) isolated native petroleum fractions that form surfactants and contain hydrogen dispiacable components including one, two, three, or four of die following types ... 

Native Petroleum Fractions in Lowering Interfacial Tensions of Aqueous Alkaline, Chemistry of Oil Recovery. edited by Johansen, R.T., and Berg, R.L., ACS Symposium Series No. 91, American Chemical Society, Washington D.C., 1979, pp 103-114. 

Asphaltene is an essential component of any dark-colored, heavy, viscous and nonvolatile oil, regardless of the oil source. Asphaltene can be obtained from the oil extracted from a naturally occurring organic-rich fossil material by a simple solvent fractionation. Asphaltene also can be obtained from the chemical conversion product of a solid fuel, such as pyrolysis or catalytic hydrogenation of coal or shale. The former is an example of the asphaltene isolated from native petroleum oil. An example of the latter is the asphaltene obtained from a synthetic crude, such as shale oil or coal liquid. 

Asphalt is defined by ASTM as a dark to black cementitious material in which the predominating constituents are bitumens that occur in nature or are obtained in petroleum processing. Asphaltene occurs in native petroleum and is enriched in asphalt when the light fractions of petroleum are removed during the refining process. 

A number of types of bituminous material exist and terminology is still somewhat confusing. The term bitumens in its widest sense includes liquid and solid hydrocarbons but its popular meaning is restricted to the solid and semisolid materials. The bitumens occur widely in nature and may be considered to be derived from petroleum either by evaporation of the lighter fraction under atmospheric conditions or by a deeper seated metamorphism. The purer native bitumens are generally known as asphaltites and include Gilsonite, extensively used for moulding, which occurs in Utah. 

Bitumen is a loosely used term (3). It is best defined to mean native substances (4) composed principally of hydrocarbons and substantially free of oxygenated bodies (5) that occur naturally as the heavy fraction of petroleum. 

For a hydroalcoholic extract of Hypericum perforatum, produced by successive extraction of dried aerial parts with petroleum ether, 1,2-dichlorethane and ethanol (50 % v/v), a sedative effect in mice has been reported [123]. The authors observed a bell-shaped dose-response effect on spontaneous motility with maximal activity at an oral dose of 26.5 mg/kg p.o, while pentobarbital-induced sleeping time was most significantly prolonged at the lowest dose applied (13.25 mg/kg p.o.). No effect on neuromuscular transmission was observed in three different test models (chimney test, traction test and rota-rod test). After separation of the crude extract in fractions containing mainly flavones, naphthodianthrones or amino acids, it was not possible to clearly attribute the effect of the native extract to a particular group of constituents. Thus, the authors conclude that activity of the hydroalcoholic extract may results form the cumulative effects of different compound, but they do not offer any explanation for the lower activity of the extract at higher doses. 

In these petroporphyrins he identified vanadium as well as iron. He established the well-known chemical association between chlorophyll in marine plants and the process of petroleum formation. It was not until 1948 that the second major metallic components in nickel were established. In the intervening years, a number of investigators have found that petroporphyrins are concentrated in the gas oil, resin and asphaltene fractions. " Baker, et at. determined the yields of petroporphyrins from a number of asphaltenes of native crudes and other bituminous materials. Data of ten sources of crude oil as well as tar sands, oil shale and gilsonite are listed in Table 1.3. 

The product obtained from wells on petroleum, natural gas and gas-condensate fields is invariably a multi-phase, multimaterial produced needs to be processed before it can be transported by pipeline and delivered to gasoline plants, oil refineries, and fractionating plants. In this context, engineers widely employ technological processes based on the principle of division (separation) of the native mixture into liquid and gaseous phases as a result of the action of intrinsic forces such as gravity or inertia. 

Crude petroleum as it is produced from the field is a relatively low-value material since, in its native state, it is rarely usable directly. However, it can be refined and further processed into any number of products whose value is many times that of the original oil. The first step in any petroleum refinery is the separation of the crude into various fractions by the process of distillation. These fractions may be products in their own right or may be feedstocks for other refining or processing units. 

---