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In this paper, the extraction residue of direct coal liquefaction residue-DCLR(ER) was used as raw material. The high-temperature reaction mechanism of Mo compound in DCLR(ER) was investigated using a synchronous thermal analyzer and the Factsage database. The high temperature reaction of DCLR(ER)-MoO3 in an oxygen atmosphere consists of pyrolysis of organic components at 400–600 °C, molybdenum trioxide sublimation at 747–1200 °C, and a stable stage at 600–747 °C. The thermal reaction process of the DCLR(ER)-MoS2 system in the oxygen atmosphere involves the pyrolysis of unreacted coal and asphaltene, the oxidation of molybdenum sulfide at 349–606/666 °C, the diffusion of MoO3 at 606/666–85 °C, and the sublimation reaction process of MoO3 at 854–1200 °C. The results show that the lower heating rate can promote the oxidation of the Mo compound and the sublimation of molybdenum trioxide. On the other hand, the oxides of aluminum, calcium, and iron in DCLR(ER) can inhibit the oxidative pyrolysis efficiency of the DCLR(ER)-MoS2 system.

In this paper, direct coal liquefaction residue was prepared from Shen-dong coal, and the solubility of the residue in five organic solvents was studied. Then, an experimental device was set up to recover molybdenum (Mo) compounds from the direct coal liquefaction residue after extraction, and the influences of sublimation temperature and duration on recycling efficiency were examined. The recycled Mo-based products were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and a thermal analyzer. The results reveal that the optimum extraction conditions were obtained through ultrasonic extraction with a quinoline solvent and the highest recycling efficiency occurred for sublimation at 900 °C for 30 min. The recycled products are identified to be α-MoO3 crystals. Moreover, the α-MoO3 crystal is thermally stable before the temperature reaches its melting point.