Direct liquefaction of lignin and lignin-rich biomass under conditions of former coal liquefaction

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Colleges, School and Institutes

External organisations

  • Karlsruhe Institute of Technology


As a waste-product from paper industry with an amount of more than 50 Mio t/a lignin is an underestimated resource for chemical industry. So far more than 98% of the processed lignin is used in form of thermal utilization, but there are other promising possibilities [1]. With its elemental composition and molecular structure showing close similarities to lignite it seems reasonable to transfer existing technologies for liquefaction of lignite to lignin. As part of an ongoing project this work is examining the liquefaction of varying feedstocks under conditions of well-known Bergius process of direct coal liquefaction by high pressure heterogeneous catalytic hydrogenation. This process could generate aromatic components for chemical industry as well as for bio based liquid fuels or additives. The gained amounts of oil product reach up to 80 wt.-%. The analytical results show that the oil phase consists in majority of aromatic monomers without hetero-atomic functional groups. This indicates that the ether and methoxy groups dominating the lignin structure were almost entirely removed by hydrogenation as water or as CO and CO2. The reaction water can be easily separated from the oil product and is dependent to the used lignin in a range of 7 to 15 wt.-%. Gaseous products obtained represent about 15 - 25 wt.-% of the products and consist of C1 to C4-hydrocarbons, CO, CO2 and H2S. The amounts of solid residues are with 3 - 10 wt.-% very low. They consist in majority of the used catalyst as well as the ash from the original lignin. For higher reaction temperatures up to 500°C there is an increase of the solid residue and the gaseous product, meanwhile for lower temperatures between 300 - 400°C higher oil yields were received. The best results were obtained for an iron catalyst directly impregnated on the lignin, meanwhile the alternative Fe-S-catalyst on an active carbon carrier resulted in higher amounts of solid residue.


Original languageEnglish
Title of host publicationDGMK Tagungsbericht
Publication statusPublished - 1 Jan 2016
EventConversion of Biomasses and Coals - Fulda, Germany
Duration: 9 May 201611 May 2016

Publication series

NameDGMK Tagungsbericht
PublisherDeutsche Wissens. Gesell. fur Erdoel, Erdgas und Kohle EV
ISSN (Print)1433-9013


ConferenceConversion of Biomasses and Coals