Influence of elemental composition on carbonization: Pyrolysis of kerosene shale and kuckersite

Abstract

Following a previous paper devoted to medium and highly oxygenated products, pyrolysis under inert atmosphere of hydrogen rich and oxygen very poor materials has been studied. Techniques used were conventional transmission electron microscopy, differential thermal analysis, thermogravimetry and IR spectrometry. Materials studied (kerosene shale and kuckersite) were natural ones but they can be considered as models for other products, provided that their elemental composition are similar. During heat-treatment, oxygen poor materials at first soften ( H/ C < 0.9), a largely extended parallel molecular orientation appearing at the end of the tar's departure ( H/ C < 0.7). The data here obtained are compared to those for oxygen richer materials. As the oxygen content increases or as they are experimentally cross-linked by oxygen, softening tends to disappear and the extent of molecular orientation decreases from a few thousand angströms to less than 100 Å. On the contrary, if tar retention is favoured by increase in pressure, autohydrogenation occurs and molecular orientation develops. General behaviour of carbonaceous materials only depends on the antagonistic equilibrium between oxygen and hydrogen.