Naphthalene-derived pitch

Figure 4. Plots of H/C ratio for anthracene- and naphthalene-derived pitches as a function of heat treatment temperature.

Figure 6. Molecular weight distributions of naphthalene-derived pitch and coke as measured by GPC.

The mass spectrum of naphthalene-derived pitch is shown in Figure 7. As with anthracene pitch, the spectrum is complex, but a detailed analysis shows the pitch to be largely composed of oligomeric species. Various species presumed to arise through bond cleavage and molecular rearrangement are also evident (21). Proposed structures for some major components are presented in Chart IV. Further heat treatment of the naphthalene pitch to... 

Figure 7. Mass spectrum obtained by FDMS for naphthalene-derived pitch. (Reproduced with permission from reference 21. Copyright 1984 Pergamon...

Chart TV. Proposed structures for some of the molecular species identified by FDMS in naphthalene-derived pitch. 

Lewis [86] found that naphthalene (I) and anthracene (II) derived pitches are complex mixtures of 2-10 units of the starting material and are only partly condensed, represented by the average structures ... 

Toshima, H., Mochida, L, Korai, Y., and Hino, T. Modification of petroleum-derived mesophase pitch by blending naphthalene-derived partially isotropic pitches. 1992 30 773-779. 

Dumont M, Chollon G, Douiges MA, Pailler R, Bouixat X, Naslain R, Bruneel JL, Couzi M. Chemical, microstructural and thermal analyses of a naphthalene-derived mesophase pitch. Carbon 2002 40(9) 1475-1486. 

Large-scale recovery of light oil was commercialized in England, Germany, and the United States toward the end of the nineteenth century (151). Industrial coal-tar production dates from the earliest operation of coal-gas faciUties. The principal bulk commodities derived from coal tar are wood-preserving oils, road tars, industrial pitches, and coke. Naphthalene is obtained from tar oils by crystallization, tar acids are derived by extraction of tar oils with caustic, and tar bases by extraction with sulfuric acid. Coal tars generally contain less than 1% benzene and toluene, and may contain up to 1% xylene. The total U.S. production of BTX from coke-oven operations is insignificant compared to petroleum product consumptions. 

Yoon, S.-H., Korai, Y. and Mochida, I., Spinning characteristics of mesophase pitches derived from naphthalene and methylnaphthalene with HF/BF3, Carbon, 1993, 31(6), 849 856. 

A number of years ago. coal tar was the primary, if not the sole, source lor hundreds of important organic chemicals and derivatives, notably the phenols, cresols, naphthalene, and anthracene, as well as other important coal lar end-prralucls, such as solvent naphtha and pitch. In recent years, synthetic processes Tor the production of phenol, the cresols and later the xylcnols. have been developed and thus, to a large extent, have pushed coal lar into the background as a source of feedstocks for (he chemical industry. 

Coal tars are by-products of the carbonization of coal to produce coke and/or natural gas. Physically, they are usually viscous liquids or semi-solids that are black or dark brown with a naphthalene-like odor. The coal tars are complex combinations of polycyclic aromatic hydrocarbons, phenols, heterocyclic oxygen, sulfur, and nitrogen compounds. By comparison, coal tar creosotes are distillation products of coal tar. They have an oily liquid consistency and range in color from yellowish-dark green to brown. The coal tar creosotes consist of aromatic hydrocarbons, anthracene, naphthalene, and phenanthrene derivatives. At least 75% of the coal tar creosote mixture is polycyclic aromatic hydrocarbons (PAHs). Unlike the coal tars and coal tar creosotes, coal tar pitch is a residue produced during the distillation of coal tar. The pitch is a shiny, dark brown to black residue which contains polycyclic aromatic hydrocarbons and their methyl and polymethyl derivatives, as well as heteronuclear compounds... 

Coal tar creosote consists of aromatic hydrocarbons, anthracene, naphthalene, andphenanthrene derivatives. At least 75% of the coal tar creosote mixture is polycyclic aromatic hydrocarbons (PAHs). Unlike the coal tars and coal tar creosotes, coal tar pitch is a residue produced during the distillation of coal tar. The pitch is a shiny, daik brown to black residue that contains PAHs and their methyl and polymethyl derivatives, as well as heteronuclear compounds. 

In addition, since this coal crude was distilled from a coal hydrogenation mixture leaving pitch, coke, and other residue behind, it is unnaturally deficient in residue compared with petroleum-based crude oil. The distillation yields show that the coal crude is especially rich in the medium naphtha-kerosene fraction boiling up to 250°C (480°F) and can be attributed to the presence of benzene (bp 80°C [176°F]), toluene (bp 111°C [232°F]), o-xylene (bp 144°C [291 ]), m-xylene (bp 139°C [282°F]), p-xylene (bp 138°C [280°F]), naphthalene (bp 218 C [424 F]), and tetralin (bp 207°C [405°F]), as well as various alkyl (methyl) derivatives of the aforanentioned compounds, hydroaromatic analogs, and alkanes. 

Yoon SH, Korai Y, Mochida I, Kato I, The flow properties of mesophase pitches and derived from methylnaphthalene and naphthalene in the temperature range of their spinning. Carbon, 32, 273-280, 1994. 

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