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It is difficult to obtain comprehensive information on coal pyrolysis with a single analytical tool due to the diversity of coal pyrolysis products. Low-temperature pyrolysis of coals with three ranks was characterized by online analytical methods to accurately explore pyrolysis mechanisms. Thermogravimetric (TG) analysis was used to characterize the basic pyrolysis characteristics of the coals. In-situ pyrolysis technique combined with gas chromatography-mass spectrometry (Py-GC/MS) and pyrolysis synchrotron radiation vacuum ultraviolet photoionization time-of-flight mass spectrometry (Py-SVUV-PI-TOF-MS) were employed in explaining the mechanism of coal pyrolysis at low temperature. The temperature of macromolecules fragmentation increases with coal rank, and a higher coal rank leads to aromatic products with a larger ring size. Different trends of adsorbed substances in coal pores with coal rank and the corresponding pyrolysis products were analyzed by Py-SVUV-PI-TOF-MS. The peak area of ethanol decreased with increasing temperature, while the pyrolysis products increased. By combining Py-GC/MS and Py-SVUV-PI-TOF-MS, possible coal macromolecular structures were obtained by reverse extrapolation of the pyrolysis products. • Two on-line MS techniques were used to characterize pyrolysis products of coals. • The fracture temperature of the coal structure is obtained by Py-GC/MS. • Adsorbed gases and pyrolysis products are distinguished by Py-SVUV-PI-TOF-MS. [ABSTRACT FROM AUTHOR]

Catalytic deoxygenation of coal is an important step to obtain high quality coal-derived liquid fuels. Bimetallic catalysts exhibit excellent hydrodeoxygenation performance, because their synergistic effects. In this work, NiO–Mo 2 O 3 /ZSM-5 was prepared by impregnation method, and applicated to catalytic hydrodeoxygenation of Wucaiwan long flame coal (WCW). The thermal dissolution (TD) and catalytic hydrodeoxygenation (HDO) of WCW were investigated using cyclohexane as the solvent. The soluble portions from TD (SF NHDO) and HDO (SF HDO) were analyzed by gas chromatograph/mass spectrometry. The relative abundance of arenes and alkanes in SF HDO increased by 12.30 % and 29.98 %, respectively, compared to that in SF NHDO. Most detected oxygen-containing compounds in SF NHDO were alcohols and ethers, and their relative abundances decreased by 50.27 % and 84.13 %, respectively, after the catalytic treatment. Thus, the cleavage of C–O bond and deoxygenation in WCW were significantly proceeded during the HDO of coal over NiO–Mo 2 O 3 /ZSM-5 catalyst. The hydrodeoxygenation mechanism was proposed according to the catalytic deoxygenation of model compounds. Mobile H+ attacks oxygen atom and iso-carbon in coal, and produces aryl-molecules and aromatic alcohols. Aryl-molecules can be also generated from the attacking of H+ to the oxygen atom in aromatic alcohols. • NiO–Mo 2 O 3 /ZSM-5 was prepared for hydrodeoxygenation of long flame coal. • The catalyst is effective for the generation of arenes and alkanes. • Hydrodeoxygenation mechanism was revealed via catalytic reaction of model compounds. [ABSTRACT FROM AUTHOR]