Jürgen Walter Stadelhofer

The manufacture of high-value carbon from coal-tar pitch

Abstract World-wide, 17 million ta −1 of coal-tar are obtained as a by product in the chamber coking process for the production of metallurgical coke. Refining of this aromatic raw material yields coal-tar pitch which is the traditional coal-derived starting material for the manufacture of carbon precursors and carbon artefacts. Considerable progress has been made in the elucidation of the physical and chemical nature of this material by means of chromatography, n.m.r. spectroscopy, thermal analysis and chemical reactions schemes. The dominant fields of application of pitch are the manufacture of pitch coke and electrode binders. Delayed coking and horizontal chamber coking are the technologies currently used for the production of cokes with low sulphur and metal content, for anodes for the aluminium-refining industry and the electric steel process. Coal-tar pitch, low in quinoline-insolubles (QI), is an excellent raw material for the manufacture of needle-cokes with a low coefficient of thermal expension (CTE). The separation of inherent QI can be performed via gravity settling in aliphatic hydrocarbon mixtures, by centrifugation in a disc separator or by filtration. The possible co-carbonization with aromatic petroleum-derived residues yields premium coke suitable for the manufacture of UHP-electrodes. New developments in the production of coke from coal-tar pitch aim to improve coke yields and increase anisotropy (i.e. low CTE and high electrical conductivity values). Further technological progress has been made in the manufacture of hard pitch which can be used as a starting material for the production of pitch coke in the chamber coking process and for the production of electrode binders by means of a continuous flash process with optimized thermal and pressure treatment of pitch, thus facilitating the ‘tailored’ manufacture of binder pitches of different qualities.

Analysis of Mixtures of Coal-Derived Phenols by 19F NMR of Hexafluoroacetone Adducts

19F nuclear magnetic resonance chemical shifts are reported for the hexafluoroacetone adducts of 21 phenols commonly found in coal-derived mixtures. Signals for the adducts of certain phenols not readily separated by gas chromatography, such as the three cresols, are well resolved. Analysis of coal-derived phenol fractions by this procedure is simple and quantitative as long as 2,6-disubstituted compounds are not present, and the mixtures are not too complex.

Solubilization of bituminous coal in aromatic and hydroaromatic solvents

Abstract The Solubilization of a bituminous coal (Ruhr District) in aromatic and the corresponding hydroaromatic compounds was compared at temperatures from 250–450°C. The solvent pair naphthalene and tetralin exhibit marked differences in solvent power as only tetralin is a ‘true’ hydrogen donor and, thus, an excellent solvent for coal. In the series of quinolines, however, the difference in solvent efficiency became significant only at temperatures ⪢350°C. The high solvent power of anthracene oil is explained on the basis of transferable hydrogen and the presence of N-heterocyclic compounds. Inference is drawn as to the optimum constitution of a vehicle oil.

Production and uses of benzene derivatives

Benzene is not only the most important aromatic raw material in terms of quantity, but it is also the most versatile from the viewpoint of its uses.

Production and uses of xylene derivatives

Whereas benzene and toluene serve as the raw materials for a wide range of products, applications for the three xylene isomers, o-, m- and p-xylene, are basically limited to chemicals arising through oxidation, i.e. phthalic anhydride (PA) from o-xylene, isophthalic acid from m-xylene and terephthalic acid from p-xylene.

Naphthalene — production and uses

Naphthalene was first isolated from coal tar in 1819 by Alexander Garden; it represents about 10% of this complex mixture of aromatics. The industrial importance of naphthalene dates from the latter half of the last century, owing mainly to the ease with which it can be converted into sulfonic acids and thence also to the naphthols, for use as dyestuffs intermediates. However, the first synthetic naphthalene-based dye was a nitro-derivative, Martius Yellow (Acid Yellow 24), which was patented in 1864 by Carl Alexander Martius.

Anthracene — production and uses

Anthracene was first discovered in coal tar by Jean B.A. Dumas and Auguste Laurent in 1832. The importance of anthracene for industrial aromatic chemistry began with the synthesis of the dyestuff alizarin by Carl Graebe and Carl Th. Liebermann, as well as by William H.Perkin in 1868, replacing the natural dye produced from madder. Anthraquinone dyestuffs have remained the most important class of dyes, alongside azo-dyes, since the beginning of the chemistry of synthetic dyestuffs.

Base materials for aromatic chemicals

The chemical industry meets its demand for carbon-containing feedstocks for the production of organic compounds from fossil raw materials — coal, oil and natural gas — as well as from renewable raw materials.

The nature of the aromatic character

Since the middle of the last century, chemists have devoted considerable effort trying to explain the chemical bond. The knowledge hitherto accumulated has also been enormously beneficial in expanding the understanding of the nature of aromatic compounds.

Additional polynuclear aromatics — production and uses

Next to anthracene, the higher condensed aromatics which are of commercial importance are phenanthrene, fluorene, fluoranthene and pyrene. Worldwide production of these polynuclear aromatics is around 2,000 tpa.