New structural concept for carbonized coals

The aim of this study was to present a model of structure for solid products of bituminous coal carbonization carried out at end temperatures (ETCs) in the 600-750 degrees range. The products are of interest since they are used as raw materials for production of activated carbons. Moreover, a layer of such products occurring in coke ovens seems to play a crucial role in generation of excessive coking pressure in industrial coking. The experimental data used in modeling were derived from the following: carbonization studies of coals and individual aromatic hydrocarbons, X-ray diffraction, transmission electron microscopy, pyrolysis-field ionization mass spectrometry, and electrical resistivity measurements, The final step of model preparation relied on application of computational chemistry for search of stable conformers and for calculations of molecular orbitals, According to the model, semicokes contain two structural components: (i) oligomers that form nonplanar 3D networks of aromatic clusters (an extended system of conjugated pi-orbitals unites clusters of the network despite the fact they are not coplanar) and (ii) planar aggregates that arise from products of dehydrocyclization reaction (the aggregates fill space between oligomeric networks). The two structural components represent optically isotropic and anisotropic phases, respectively.