Coliquefaction of Lignite and Corn Stalk in Ethanol–Water Mixed Solvent with Addition of Formic Acid and Iron Ore Catalyst

Abstract

The coliquefaction of Xilinguole lignite (XL) and corn stalk (CS) was carried out in water, ethanol, and ethanol–water mixed solvent at different mixing ratios with or without iron ore as catalyst, under initial N2 atmosphere. Results showed that ethanol improved the liquefaction and coliquefaction of XL and CS. The liquefaction of XL and CS separately resulted in 31.0 and 41.9 wt % of oil yield in ethanol and 7.3 and 20.2 wt % of oil yield in water, respectively, whereas the ethanol and water coliquefaction process resulted in 34.4 and 13.2 wt % of oil yield, respectively. The addition of formic acid increased the oil yield in the single liquefaction of XL and CS and their coliquefaction in ethanol, water, or ethanol–water (50:50, v/v). The liquefaction of XL and CS and coliquefaction of XL/CS in ethanol at N2 atmosphere with formic acid resulted in higher oil and conversion yields, suggesting that formic acid can supply active hydrogen. Also, iron ore was an effective catalyst, for instance, adding 20 w...