EPR and IR studies on the role of coal genetic type in plastic layer formation

•High- and low-sulfur coking coals and their blends were investigated.•During plastic layer formation the coking blend components chemically interact.•Good coking capacity is associated with a high content of paramagnetic centers.•Coal type by reductivity must be in consideration when making coking blend.

Coal blends with all possible combinations of two pairs of isometamorphic coals of different sulfur levels were pyrolysed in centrifugal field, allowing to be separated into solid, fluid and gaseous products. It has been shown that the replacement of the low-sulfur by the high-sulfur coking coal of the same rank (≈ 83–88% Cdaf) in blends leads to a substantial increase of fluid product yield which can be of great practical value. Using the EPR and DRIFT-spectroscopy methods the structural peculiarities of the obtained products have been studied. An apparent relation between the content of sulfur in coal, paramagnetic centers in plastic layer and coal coking ability was established. It was demonstrated that the concentration of paramagnetic centers in fluid non-volatile products correlates with the yield of plastic layer responsible for coking ability.