Solvent-extracted pitch

In recent years researchers at West Virginia University have developed coal-derived pitches on a laboratory scale in quantities sufficient to make 1 kg samples of calcined coke for fashioning graphite test specimens. The pitches were derived by uhlizmg solvent extraction with N-methyl pyrrohdone (NMP). This solvent is able to isolate coal-based pitches m high yield and with low mineral matter content [13]. It is this work that will form the basis of the discussion for the later part of this chapter. 

It has been demonstrated that a solvent-extraction procedure with N-methyl pyrrolidone is capable of producing coal-derived extract pitches with low-ash contents. Moreover, the properties of the pitches can be varied by partial hydrogenation of the coal prior to extraction. The yield of the pitches along with the physical and chemical properties of the cokes and graphites vai in an understandable fashion. 

Bulk processes of carbonization can be "stopped" at an appropriate stage and mesophase separated from the remaining pitch by solvent extraction. Spheres of mesophase can then be isolated. However, from the viewpoint of specialised industrial usage, e.g. spinning /moulding (not traditional coke-making) such mesophase can be said to be "overcooked". It is not readily soluble in generally available solvents it does not represent a minimum in its visco-elastic properties. 

Figure 1 The status of carbon fiber development in 1984 based primarily on product data supplied by manufacturers. The solid line refers to commercial grades of fiber spun from mesophase pitch ( 7) the dashed line refers to an experimental mesophase fiber spun from solvent-extracted pitch (10). Experimental (noncommercial) fibers are indicated by triangular symbols.

A patented process has been developed for the production of electrode binder pitch from petroleum-based materials. Carbon anodes produced from the petroleum-based pitch and coke have been used successfully on a commercial scale by the aluminum industry. One stage of the process involves the pyrolysis of a highly aromatic petroleum feedstock. To study the pyrolysis stage of the process a small, sealed tube reactor was used to pyrolyze samples of feedstock. The progress of the reaction is discussed in terms of the formation of condensed aromatic structures, defined by selective solvent extraction of the reaction product. The pyrolysis of the feedstock exhibits a temperature-dependent induction period followed by reaction sequences that can be described by first-order kinetics. Rate constants and activation energies are derived for the formation of condensed aromatic structures and coke. 

Pine Oil. Yarmor. An oil from Pinus palustris Mill, and certain other species of pines, Plnaceae. It is obtained from pitch-soaked pine wood by steam distillation or solvent extraction followed by steam distillation and also by destructive distillation. It consists mainly of isomeric tertiary and secondary, cyclic terpene alcohols. 

Solvent-Extracted Pitch Precursors for Carbon Fiba ... 

Pitch is a "pseudo solution" of a wide variety of different generic classes of hydrocarbons ranging from paraffins at one extreme to very highly aromatic species at the other. By using the Theory of Solubility for Non-Electrolytes, specific fractions can be isolated from a pitch by properly selecting a solvent system and extraction conditions. "Tailored" precursors for carbon fiber and other carbon products, such as carbon/carbon matrices and bulk graphites, can thus be obtained. The technique of extraction, the characteristics of different precursors, and the structure and properties of carbon fiber and composites made from solvent extracted precursors will be discussed. 

In this paper, a process for producing a carbon fiber from a solvent extracted pitch feed will be discussed. 

An Exxon cat cracker bottom pitch was extracted with solvents of varying solubility parameter in order to evaluate the relationships which exist between extraction conditions and the characteristics of the extracted product. The precursor pitch possessed a carbon/ hydrogen ratio of 1.49 and a alculatedO, overall average solubility parameter of 10.48 reflux quinoline insolubles content of the pitch was 2.3% and the refluxing toluene insolubles were at a level of 20.3%. The pitch was not optically anisotropic. Upon heating in N2 to 530 C in a TGA, a coke yield of 37% was obtained. 

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