硫对煤直接液化反应性影响及其迁移机制

Direct coal liquefaction reactivity under sulfur’s effect was studied via L₉（3⁴） orthogonal experimental design. Pressure，temperature， H₂S volume content in H₂S/H₂， and S/Fe mole ratio were considered as factors while total conversion， oil yield， sulfur content of oil， and hydrogen consumption ratio as the target indexes. The sulfur migration mechanism in the reaction was inferred according to the results. The following conclusions could be confirmed or inferred from this work：Temperature has a remarkable effect on oil yield. From 420 ℃ to 470 ℃， there’s an average increase of 19.0% in oil yield. H₂S plays three roles： hydrogen consumption ratio decrease， light product （including oil and gas） generation， yet more sulfur content of oil. There is a decrease of 0.3% hydrogen consumption ratio and an increase of 0.9% sulfur content of oil ranging from 0- 1% H₂S volume content. S/Fe mole ratio within the reasonable range can promote oil yield， as 0.8 S/Fe mole ratio achieves a better oil yield than both 0（extra- 7.2%） and 1.6（extra-3.6%）. During the processing of DCL，elemental sulfur migrates to THFI mostly，as there’s an extra 2% sulfur content of THFI if only elemental sulfur is added in the reaction system. According to the results of the orthogonal experiment，the liquefaction experiments with different S/Fe molar ratios in a pure hydrogen atmosphere，and different H₂S volume content in H₂S/H₂ under a constant 0.4 S/Fe molar ratio were further studied. From the distribution of sulfur in oil and asphaltene，combined with the changes in functional group，and free radical concentration，the effect mechanism of H₂S and elemental sulfur and the migration rule of sulfur in coal liquefaction reaction were deduced. It was indicated that the free radical concentration of THFI is to some extent related to both oil yield and hydrogen consumption. Oil yield shows a peak value at 1.2 S/Fe atomic ratio while the free radical concentration of THFI gets its minimal value. At 0.25% H₂S content，the hydrogen consumption rises apparently while the free radical concentration of THFI reaches bottom peak. It seems to be easier for H₂S than elemental sulfur to react with the precursor of light products，and promote conversion of heavy fraction to the light products. Only in excessive amounts can elemental sulfur combine with asphaltenes slightly. The common point of H₂S and elemental sulfur is that they promote hydrogen supply in the gas phase，but have no obvious effect on the functional groups of asphaltene.