The influence of addition of coal tar pitch (CTP) and expired pharmaceuticals (EP) on properties and composition of pyrolysis products for lower and higher rank coals

• CTP and EP additives increase the thickness of plastic layer of studied coals.
• Additives interact with low molecular compounds easier than with macromolecules.
• Addition of CTP decreases amount of identified PAHs in plasticized LRC by 5 times.
• Addition of CTP decreases amount of identified PAHs in plasticized HRC by 1.43 times.
• Addition of EP increases amount of identified PAHs in plasticized HRC by 1.84 times.

Changes in electrical resistivity and tangent of dielectric losses of pyrolyzed coals were determined along with the yield of organic material soluble in dichloromethane (OMSDCM) obtained from coals plasticized with addition of CTP and EP. No proportionality between the height of the maximum of electrical resistivity parameter of pyrolysates in the plasticity state and the yield of OMSDCM was noticed. The pyrolysates (obtained with and without additives) corresponding to the plasticity state and OMSDCM were analyzed with the FT-IR method. It was stated that the additives cause greater changes of structural-chemical parameters in OMSDCM than in the pyrolysates. It was observed that a steady change in composition of the extracted material takes place under the influence of additives in the plasticity state. The amount of determined polycyclic aromatic hydrocarbons (PAHs) decreases almost by 5 times in composition of OMSDCM from the zone of maximum plasticity of LRC under the influence of CTP, and from the weakened zone of HRC – almost by 1.43 times. The addition of EP causes an increase in amount of the determined PAHs in OMSDCM from the weakened zone of HRC by 1.84 times; in the composition of OMSDCM from the gas-saturated zone of LRC the content of PAHs determined during the experiment decreases.