Heat Treatment Of Pitch Research Articles

Carbon/carbon composites with heat-treated pitches: I. Effect of treatment in air on the physical characteristics of coal tar pitches and the carbon matrix derived therefrom

Coal tar pitch has been heat treated at 350°C in the presence of air and nitrogen for different times. The treatment temperatures have been pre-estimated from the behaviour of pitch during heat treatment in the presence of air. The modified pitches so obtained have been characterised by FTIR, TGA, DTG, DSC, elemental analysis, etc. FTIR studies reveal that the aromaticity of the pitches increases with heat treatment in air at 350°C up to 5 h. TGA studies also exhibit characteristic differences in pyrolysis behaviour of these pitches. C/H ratio and the coke yield have been found to initially increase with treatment time but decrease with longer heat treatment. Comparison of thermal analysis data, C/H ratio and FTIR studies show that during heat treatment of pitch in air, polymerization dominates volatilization of low molecular weight compounds in the pitch.

Fluorescence spectroscopic analysis of benzo[ a]pyrene in coal tar and related products

Direct quantitative fluorescence spectroscopic analysis of benzo[ a]pyrene in coal tar, without sample fractionation, was shown to be valid by analysis of a standard reference coal tar (with certified concentrations for 12 polycyclic aromatic hydrocarbons) and a mixture of 16 polycyclic aromatic hydrocarbons of known concentration. This simple and rapid method was applied to the analysis of benzo[ a]pyrene in coal-tar pitch, a coal-tar-derived heavy residual oil, coal-tar pitch fractions and the volatiles from heat treatment of pitch (both coal-tar and petroleum). However, high values were obtained for the analysis of perylene in the same samples due to the presence of benzo- and dibenzoperylenes with similar spectra to perylene.

96/00266 Effect of light fraction on the increase in benzene-insoluble content during heat treatment of pitch

96/00266 Effect of light fraction on the increase in benzene-insoluble content during heat treatment of pitch

Extraction of coal-tar pitch and the effect on carbonization

The extraction of a QI-free coal-tar pitch was investigated using supercritical fluid extraction with aliphatic hydrocarbons at 250–350°C and 10–15 MPa and by liquid extraction at 150–200°C. The softening points, number-average molecular weights, and toluene insoluble (TI) content of the residual pitches increase with the amount of lower molecular weight species extracted. The amount of mesophase formed in a given time and the Alcan coking value of the pitches show good correlations with the molecular weight and TI of the pitches. A process based on heat treatment of pitch under pressure followed by supercritical fluid extraction for preparation of mesophase pitch was investigated.

Binderpechpyrolyse an oxidkörnern und glühverhalten der pyrolyserückstände

The influence of oxidic filler grains on the pyrolysis behaviour of binder pitch was studied by thermogravimetric, chemical, polarisation and electron microscopic as well as by X-ray methods. It is shown that oxidic surfaces hinder the mesophase formation during heat treatment of pitch. Higher H/C ratios as well as diminished pyridine solubilities of the HT residues and higher coke yields are found in comparison with the pyrolysis behaviour of pure pitch. As the oxide type is less important than the amount of wetted surface area, all observed effects are explained by physical adsorption phenomena.