A Rational SeparationStrategy for Low-TemperatureCoal Tar: Integrating Dual-Solvent Extraction, Structure-OrientedLumping, and Quantum Chemical Analysis

Abstract Selective separation of alkanes, arenes, and arenols from low-temperature coal tar (LTCT) is critical for its value-added utilization, yet still challenging owing to its complex composition. This work proposes an integrated strategy combining dual-solvent extraction (DSE) and molecular-level understanding to overcome this challenge. Six solvent systems were systematically evaluated. The acetonitrile-carbon disulfide system achieved a high total extraction yield of 97.66%, while the methanol-carbon disulfide system exhibited excellent alkane selectivity, enriching their relative content to 44.65%. Molecular characterization identified 302 compounds in extracts. A structure-oriented lumping model distinguished key structural units to guide downstream upgrading. Quantum chemistry and energy decomposition analysis provided molecular-level insights into the interaction mechanisms that qualitatively inform the observed separation behavior. Extraction is controlled by hierarchical intermolecular interactions. Universal dispersion forces dominate, while strong O–H···O hydrogen bonding (e.g., methanol-p-cresol) determines the high component selectivity. This study establishes an efficient DSE process for LTCT and provides mechanistic insights, offering a molecular-level theoretical framework for rational design and optimization of separation processes for complex coal-derived liquids.