Modelling the relationship between carbon aromaticity of lignite pyrolysis chars and the process temperature with petrographic parameters

For replacing the cost and time consuming C-13 DP-MAS NMR spectroscopy reliable models describing the development of the carbon aromaticity of pyrolysis chars with increasing process temperature should be evolved by means of the micropetrographic parameters reflection, remission, Vickers microhardness and content of semicoke. It has shown that componential constitution and remission is rather caused by the process temperature and depends therefore only indirectly on the aromaticity. The parameters' reflectance and microhardness, however, increase with increasing aromaticity due to the higher molecular ordering, even if the relationship is not linear. All obtained correlations are highly significant and well fitted, but the model concerning the reflectance leads to most appropriate results.