Catalytic co-liquefaction of lignin and lignite coal for aromatic liquid fuels and chemicals in mixed solvent of ethanol-water in the presence of a hematite ore

Abstract

In this work, a raw hematite ore (Fe2O3) displayed to be a low-cost but effective catalyst for co-liquefaction of hydrolysis lignin (HL) and Xilinguole lignite (XL) in ethanol-water (50:50, v/v) mixed solvent under initial N2 atmosphere to produce heavy oil (HO) as a potential source of liquid fuel and aromatic chemicals. The liquefaction of HL and XL separately without catalyst resulted in a maximum of approx. 18 and 11 wt% yield of HO, respectively, while the co-liquefaction process resulted in up to approx. 26 wt% of HO, indicating synergy effect in co-liquefaction of lignin and lignite. The addition of the hematite ore in the co-liquefaction operation produced HO at a very high yield of about 40 wt% at 400 °C for a residence time of 2 h, nearly doubling that of the operation without catalyst. The Produced HO products from the co-liquefaction operations at 400 °C for2 h contain significant concentrations of low molecular weight aromatics at ∼14 mg/g-HO in the presence of non-reduced hematite or goethite, and ∼17 mg/g-HO in the presence of reduced hematite or goethite, compared with only <5 mg/g-HO without iron ore catalyst.