Premium coke

The property of mesophase that makes it suitable for carbon fiber and premium coke manufacture is that it forms ordered stmctures under stress which persist following carbonization. However, most carbon fiber production in the 1990s is based on polyacrylonitrile (PAN). 

Coals mesophase pitch coal chars coal tar pitch carbon mesocarbon microbeads, carbon fibers semi-coke, calcined coke activated carbons premium cokes, carbon fibers, binder and matrix... 

The gas oil fractions obtained from the fractionation of the cat-cracker reaction product are rich in aromatics. They are therefore suitable as a basis for the recovery of polycyclic aromatics, e.g. naphthalene. Because of the high C/H ratio, they can also be used for the production of high-value carbon in the form of premium coke and as feedstock for the manufacture of carbon black (see Chapter 13). 

Some of the constituents of pyrolysis tar, such as the unsaturated C9 compounds and naphthalene, can be used as chemical raw materials. Because of its high G/H ratio, pyrolysis tar is also suitable for use as a raw material in the production of carbon black and as a feedstock for coking to premium coke (see Chapter 13.1.2). 

The cracker tar which is generated by this process is suitable as feedstock for production of premium coke in the delayed coker the gasoline quality is somewhat better than that of coker naphtha. 

The mesophase phenomenon, discovered by James D. Brooks and Geoffrey H. Taylor in 1965, made a decisive contribution to the understanding of the production of high-value carbon products from mesophase pitch, such as premium coke by delayed coking and carbon fibers by spinning. 

Manufacture of high-value coke (premium coke) with simultaneous production of minor amounts of liquid and gaseous hydrocarbons, i.e. the production of premium coke from highly-aromatic residues (coal-tar pitch, pyrolysis residues from naphtha cracking, residues from thermal and catalytic cracking). 

Figure 13.9 shows the four delayed coker units operated by Conoco, Immingham/England, which have a production capacity for 300,000 tpa of premium coke. 

Property Premium coke calcined at 1620 K Regular coke Metallurgical coke... 

Premium coke is an extremely well graphitizing carbon with a high degree of optical anisotropy (isochromatic areas of optical texture above about 100 pm) and is characterized by a combination of the following properties which differ significantly from those of regular coke high real density, low reversible thermal expansion, and low ash content combined, in most cases, with low sulfur content. 

Premium coke is mainly produced from tars or residues from petrochemistry by the delayed coking process. Also refined coal tar pitches are used as precursors for premium coke production. 

Typical characteristics for regular coke in comparison with those 0/metallurgical coke and 0/premium coke calcined at 1620 K are ... 

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