Products analysis of Shendong long-flame coal hydropyrolysis with iron-based catalysts

•Fe2S3 catalyst is active for upgrading low-temperature coal tar•The highest tar yield and reactivity of semi-cokes were achieved over Fe2O3-oleic acid•The molecular weight distribution of each component in LTCT is given.

This paper focuses on the effect of Fe2O3, Fe2S3, Fe2O3-oleic acid, FeS, and FeSO4 on hydropyrolysis of Shendong long-flame coal. The experiments were conducted at 650 °C and 0.1 MPa in a novel lab-scale-fixed-bed reactor. For non-catalytic hydropyrolysis process, the char, tar and gas yields were 73.5 wt.%, 7.9 wt.%, and 12.1 wt.%, respectively. In terms of catalytic hydropyrolysis, the highest conversion of coal and tar yields (8.4 wt.%) was observed when Fe2O3-oleic acid was used. The strong decomposition capability of the iron-based catalysts had negative effects on the tar yield, but favored the formation of the n-hexane soluble compounds. Particularly with Fe2S3 as a catalyst, the tar yield decreased from 7.9 wt.% to 7.0 wt.%, while the n-hexane soluble contents of the tar increased from 70.6 wt.% to 81.0 wt.%. The yield of lightweight components increased about 0.1 wt.%. A molecular weight reduction in the tar and the heavy compounds, which confirmed the ability of iron-based catalysts to make the heavy oil be light. The characteristic temperatures of char gasification with CO2 had little change.

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