Developing Additives Based on Russian Coal for the Thermal Hydrocracking of Heavy Tar 3. EPR, NMR, and IR Spectroscopy

Abstract—This article forms part of research on the selection of coal for the production of activated carbon to be used in the thermal hydrocracking of heavy tar residues. It is devoted to the use of electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), and infrared (IR) spectroscopy to determine the structural and molecular composition of Berezovsky and Kaichaksky-1 lignite and also D coal, in selecting the optimal coal for sorbent production. Comparison of the IR and NMR results indicates that the aliphatic side chains in the selected coal samples are shorter than those in other Siberian coal samples. Comparison of NMR and EPR data shows that, compared to Berezovsky lignite, Kaichaksky-1 lignite has a higher content of oxygen-bearing groups. Its paramagnetism is due to the presence of aroxyl radicals of semiquinone and phenoxyl type. EPR spectroscopy indicates that Kaichaksky-1 lignite has the highest content of paramagnetic complexes based on Fe³⁺. That may affect the quality of the sorbents produced.