Insight of oil-soluble Fe-based catalyst for direct liquefaction of Shangwan coal

Abstract

Oil-soluble Fe-based catalysts with different carbon numbers of ligand were prepared to investigate the action mechanism of oil-soluble catalyst on direct coal liquefaction. Results showed that the increment of ligand carbon numbers decreased the average grain size of active phase Fe_1-xS, promoted activation of gaseous and solvent hydrogen and coal conversion into oil. Oil yield was remarkably increased from 57 wt% to 68 wt% with increasing carbon number in ligand from 8 to 18. A linear relationship between oil yield and oil-wetness of Fe-based catalysts was constructed. Ligand and Fe contributed to oil yield increment about by 5 wt% and 10 wt%, respectively. Oil yield was enhanced via participating in annihilation of coal pyrolysis free radicals by H-rich radicals from cleavage of oil-soluble ligands. When highly active iron stearate was used, almost similar oil yield at initial H₂ pressure of 6.50 MPa as that under 7.00 MPa indicated that liquefaction condition could be alleviated.