Abstract
This study presents the results of a comprehensive experimental investigation of the co-pyrolysis processes of carbon-containing wastes of various origins, including coal dust from the Kulan deposit, plastic waste based on polyethylene and polypropylene, gossypol resin isolated from soapstock generated during cottonseed oil production, and oil sludge from the “Petro Kazakhstan Oil Products” refinery (Shymkent). The experiments were carried out over a wide temperature range of 500–700 °C at atmospheric pressure in inert (N₂) and weakly acidic (CO₂) gas atmospheres. Fractional separation and identification of the components of the liquid pyrolysis products were performed using extraction methods. It was established that the nature of the gas medium and the process temperature exert a decisive influence on the yield and distribution of oil, resin, asphaltene fractions, and insoluble substances. It was shown that the thermocatalytic cracking of individual wastes and their mixtures (1:1:1:1) results in the formation of a liquid product dominated by oils and resins with a reduced asphaltene content. A pronounced synergistic effect of co-pyrolysis was identified, associated with the destruction of polyphenolic structures and fatty acids of gossypol resin, leading to hydrogen formation that contributes to the stabilization of active hydrocarbon radicals generated during the thermal decomposition of coal dust and polymer waste. This promotes the intensification of secondary synthesis reactions with the formation of olefins, aromatic hydrocarbons, and resinous compounds, as well as a redistribution of the fractional composition of liquid products toward an increased oil fraction at elevated temperatures. Gas chromatography–mass spectrometry analysis demonstrated that co-pyrolysis of the multicomponent mixture ensures the formation of hydrocarbon products with a uniform distribution across the main classes of compounds, confirming the potential of this approach for the integrated processing of heterogeneous carbon-containing wastes.