Petroleum, major fractions

Petroleum, a complex mixture of many different hydrocarbons, is the main source of alkanes. Petroleum can be processed into various fractions by boiling a mixture in huge distilling towers. Each fraction contains alkanes with a relatively narrow range of molar masses. Table lists these major fractions of petroleum and some of their uses. As the table shows, these compounds are the principal sources of energy in our society. 

Table 9-1 Major Fractions of Petroleum and Their Uses...

Thus, in the simplest sense, petroleum and petroleum products can be considered to be composites of four major fractions (saturates, aromatics, resins, and... 

On the other hand, the complex mixture of petroleum hydrocarbons potentially present in an air sample can be minimized by separation of the sample into aliphatic and aromatic fractions, and then these two major fractions are separated into smaller fractions based on carbon number. Individual compounds (e.g., benzene, toluene, ethylbenzene, xylenes, MTBE, naphthalene) are also identified using this method. The range of compounds that can be identified includes C4 (1,3-butadiene) through C12 (n-dodecane). 

For a variety of reasons, it is often necessary to define a feedstock in terms of its physical composition (ASTM, 1995). Furthermore, the physical composition of heavy oils and residua vary markedly with the method of isolation or separation, thereby leading to further complications in the choice of suitable processing schemes for these feedstocks (Speight, 1999 and references cited therein). However, in the simplest sense, petroleum and heavy feedstocks can be considered to be composites of four major fractions (Figure 3-8). The nomenclature of these fractions lies within the historical development of petroleum science and that the fraction names are operational and are related more to the general characteristics than to the identification of specific compound types. Nevertheless,... 

The first step in refining petroleum is a careful fractional distillation. The products of that distillation are not pure alkanes but mixtures of alkanes with useful ranges of boiling points. Table 3-3 shows the major fractions obtained from the distillation of crude petroleum. 

TABLE 3-3 C Major Fractions Obtained from Distillation of Crude Petroleum... 

Research on bimetallic catalysts has had a major impact in the reforming of petroleum naphtha fractions to produce high octane number components for gasolines. During the 1970s, bimetallic catalysts largely replaced traditional... 

Canada is the world s third largest producer of natural gas and eleventh largest producer of crude oil. Canada produces much more petroleum and natural gas than is consumed in the domestic market. Consequently, petroleum and natural gas export plays a very important role in the Canadian economy. Another factor that influenced the activity in the Canadian petroleum industry was the pipeline expansion in the year 2000. This opened up new markets. A major fraction of petroleum products are exported to markets in the United States. 

Scheme 1. Convenient separation of petroleum into four major fractions.

Many of the commonly known solvents are aetually petroleum distillation fractions and are eomposed of a number of compounds (e.g., mineral spirits and naphthas). There are two general types of solvents derived from petroleum, aliphatics or aromatics. Aromatics are stronger solvents than aliphatics since they dissolve a wider variety of resins. Most major solvent suppliers (chemical manufacturers) produee several types and variations of these solvents and the associated HAP contents can vary significantly from manufacturer to man-ufaeturer and from batch to batch. These types of solvents are used extensively and are present in the majority of marine coatings. Table 14.26.4 provides a summary of common petroleum distillate solvents and solvent blends and their associated HAP content. For any... 

SEC has long been recognized as a major technique for the characterization of materials of high molecular mass, i.e., polymers. The application to small molecules (molecular mass 1000) has received much less attention. One of the first applications of SEC in the authors laboratory was the separation of dimer acid (MW c.500) from a petroleum fuel fraction in 1968, and there has been a constant succession of subsequent analytical applications as well as the more conventional projects on polymer characterization. 

The regular increase in boiling point of the alkanes with increasing chain length is of immense commercial importance. It is the basis of the initial refinery process of fractional distillation whereby crude oil is separated into useful fractions (Figures 10.10 and 10.11). Crude oil (or petroleum) is the major commercial source of hydrocarbons for a variety of uses as fuels and chemical feedstock. Figure 10.11 shows the components present in the major fractions obtained by distillation at an oil refinery. 

The growth of the polymers and plastics industries has meant that a major fraction of the workforce in developed countries is either directly or indirectly employed by plastic-related jobs. As more stable and less costly plastics are developed, more applications are found and growth continues. Because polymers and plastics are based on petroleum and since petroleum is a limited resoiffce, it is essential that continued efforts be made to recycle our plastic wastes—something that is slowly being realized. 

Petroleum is a naturally occurring oily, flammable liquid composed principally of hydrocarbons (50-98%) with the remainder consisting of organic compounds, oxygen, nitrogen, sulfur, and traces of metal salts. Petroleum is usually found beneath the earth s surface and occasionally in pools above the surface. Unrefined petroleum is called crude oil. Petroleum is separated by distillation into the following four major fractions ... 

The majority of xylenes, which are mostly produced by catalytic reforming or petroleum fractions, ate used in motor gasoline (see Gasoline and other MOTORFUELs). The majority of the xylenes that are recovered for petrochemicals use are used to produce PX and OX. PX is the most important commercial isomer. Almost all of the PX is converted to terephthaUc acid and dimethylterephthalate, and then to poly(ethylene terephthalate) for ultimate use in fibers, films, and resins. 

Since the majority of middle distillates are used as a fuel, combustion of these products will contribute to SO2/SO3 air pollution and acid rain. However, in catalytic processes of petroleum fractions Sulfur levels are also important. Lor instance, quantities... 

Crude oil is the source for over. 1,(1(1() petroleum-based products for both industrial and consumer applications. The technique of distillation, the first stage processing of petroleum, exploits the different boiling points of the various petroleum fractions to separate out and isolate for use the different portions of the crude. The type and proportions of hydrocarbons present in each fraction depends upon the type of crude oil used and the range of temperatures employed. The major products produced directly... 

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