*2.2. Physicochemical Characterization*

The proximate analysis of all samples was performed to estimate the volatile matter, ash content, moisture, and fixed carbon using appropriate ASTM protocols (E1755-01, 2020; ASTM E1756-08, 2020; E871-82, 2019; E872-82, 2019; D1762-84, 2021). The percentages of carbon, hydrogen, nitrogen, and sulfur were determined using the CHNS analyzer (Euro EA 3000, Eurovector, S.p.A., Milan, Italy) and oxygen was calculated by difference. The higher heating value (HHV) was calculated according to the formula presented in the work [32]. The content of macro- and microelements was studied using the energydispersive fluorescence X-ray spectrometer (EDX-800HS2, Shimadzu, Kyoto, Japan) by a semi-quantitative method. Gas chromatography–mass spectrometry of the pyrolysis liquid were carried out on spectrometer (GCMS-QP2010, Shimadzu, Japan) on HP-5MS column (0.25 μm, 30 m). The evolved gas was analyzed by a gas chromatograph Chromatec-Crystal 5000.2 (Chromatec, Yoshkar-Ola, Russia) using GOST 32507−2013 and ASTM D 5134-98, 2008. The gas samples were delivered to the given machine from the autoclave's gas output through special heat-resistant tubing. The gas separation was carried out in capillary column with a length of 30 m and two absorption chambers. Chromatography was run in following temperature mode: 90 degrees for 4 min, from 90 ◦C to 250 ◦C with the heating rate of 10 ◦C/min. The gas carrier was helium and the stream velocity was 2.5 mL/min.

#### *2.3. Pyrolysis Experimental Procedure*

Pyrolysis was carried out on a laboratory setup described in [8]. The initial temperature was 25 ◦C, the heating rate was 10 ◦C/min, and the temperature of the pyrolysis process itself was 550 ◦C. The material balance was determined according to the method presented in [8,33]. Each experiment was repeated at least three times.
