High-temperature Pitch Research Articles

Method for the determination of the α1 fraction in high-temperature coal pitch, sludge, and bottom sediments

Method for the determination of the α1 fraction in high-temperature coal pitch, sludge, and bottom sediments

Production of granulated pitch

The production of granulated high-temperature coal-tar pitch has been successfully introduced at the Karaganda Metallurgical Combine. This material is used as a thermal plasticizing agent in the production of refractories, especially those used to line blast-furnace notches.

Efficiency of sequential elution solvent chromatography-extrography technique for the characterization of hydroliquefaction and pyrolysis products

A Separation method that combines extrography (EX) and sequential elution solvent chromatography (SESC), called SESC-EX, was used for the characterization of products derived from hydroliquefaction of a French coal and of pitches obtained from coal and petroleum tars. The selected examples show the efficiency of this technique for the evaluation of the effects of reaction temperature on the hydroliquefaction products and the characterization of pitches according to their origins (low (LT) and high (HT) temperature pitches). Further data on the chemical structure of pitches were obtained by chromatographic and spectroscopic analyses. All these methods showed marked differences between LT and HT pitches.

Analysis and solvolysis of pyrolysis pitches: comparison between high and low temperature pitches

The solvolysis of two pitches obtained by carbonization of coal at low and high temperatures respectively, was studied in four solvents (tetralin, tetrahydroquinoline α-naphthol and tar of petroleum origin). The methodology of experiment design was applied. Conversion or regression reactions were observed according to the solvent, the temperature, the concentration and the nature of the tars.

Interactions between pitch constituents in thermal treatment: 1. Behaviour of extrographic fractions by heating at 350, 400 and 450 °C

The thermal treatments of coal tar and petroleum pitches, of their fractions obtained by extrography and of mixtures of these fractions, have been achieved at 350, 400 and 450 °C. Experimental results show the differentiation between low and high temperature pitches, and the influence of their chemical constituents on their thermal behaviour. The solvolytic or cross-linking action of some of them was pointed out.

The pyrolysis of acenaphthylene studied by proton nuclear magnetic resonance

The thermally induced transformations of acenaphthylene during pyrolysis at temperatures up to 800 K have been monitored dynamically by pulsed-proton NMR thermal analysis techniques. Measurements have been made of both the transverse and the spin-lattice relaxation properties of the protons during heating at 2, 4 and 8 K/min and subsequent isothermal treatment for up to 300 min. As well as clearly delineating the melting of acenaphthylene and the formation and decomposition of polyacenaphthylene, these two NMR properties have been used to follow the transformation of the high-temperature pitch to produce anisotropic mesophase and semicoke. It is concluded from these NMR results, together with supplementary information obtained from differential scanning calorimetry (DSC) experiments and from examination of the pyrolysis residues by ESR, NMR and polarized light microscopy, that 1. (a) the free radical concentration attained by the intermediate pitch during uniform heating is critical in determining the transformation rate of the pitch, which is found to be greater both for pitches prepared by slower heating and for those treated at higher temperatures 2. (b) the preparation of the intermediate pitch by more rapid heating is conducive to mesophase formation during subsequent isothermal treatment because it extends the duration of high molecular mobility, and 3. (c) the appreciable concentration of aromatic free radicals in the residue decreases significantly with time after cooling to room temperature if condensation and cross-linking reactions have not progressed sufficiently during the high-temperature treatment of the pitch.