Hydro-liquefaction of the ashless coal from de-polymerization of Shengli lignite

Abstract

This work performed de-polymerization of Shengli lignite (SL) to remove minerals, and the resultant product (denoted as SDP) was subjected to hydro-liquefaction to prepare value-added aromatic products, especially n-hexane soluble fractions (HS for abbreviation). Compared with raw lignite, SDP is easily converted to light products (HS) with low H2 consumption due to its small molecular weight and less free radicals generated during hydro-liquefaction. Appropriate temperatures (e.g., 400 °C) are required for efficient conversion of SDP into HS fractions. Ni-Mo-S/Al2O3 catalyst effectively promotes hydrogenation of SDP into HS during the reaction, moreover, the condensation reaction is effectively reduced. The yield of HS (YHS) reaches to 73.7% and the yield of THFI (YTHFI) is only 2% with the use of Ni-Mo-S/Al2O3 at 400 °C. The Aromatic fractions in the solvent effectively reduce YTHFI through suppression of condensation reaction, and the hydrogen donor solvents remarkably increase YHS. The HS fractions primarily consist of aromatic hydrocarbons with 1–3 rings and aromatic derivatives containing alkyl as well as various oxygen-containing functional groups.