A thermal process which increases the molecular aggregation or
association in petroleum-based residues or
coal tar pitches leading to extended
mesophase domains. This is achieved by holding them at an elevated temperature (usually
-
) over a period of time
(
to
).
It is performed in a
coking drum and is designed to ultimately produce
delayed coke The feed is rapidly pre-heated in a tubular furnace to about
.
Note:
Needle coke is the premium product of the delayed
coking process. It is generally produced from highly aromatic residues from, for instance,
the steam
cracking of gas oil. Its appearance and preferred orientation of the
graphene layers is a consequence of the evolved gaseous products percolating through the
mesophase which must not have too high a
viscosity. A close control of temperature, time and feedstock is essential. Lower grades, for
instance
isotropic cokes, are used for
carbon electrodes applied, for example, in the production of aluminium.
Source:
PAC, 1995, 67, 473
(Recommended terminology for the description of carbon as a solid (IUPAC Recommendations
1995))
on page 486
Cite as:
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by
A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997).
XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic,
J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8.
https://doi.org/10.1351/goldbook.
