Hydrotreating and hydrothermal treatment of alkaline lignin as technological valorization options for future biorefinery concepts: A review

Cathelijne Rutten*, Andrea Ramírez, John Posada Duque

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

20 Citations (Scopus)

Abstract

Lignin has the potential to be a sustainable resource for producing biobased chemicals (e.g. phenols, aromatic hydrocarbons, vanillin) for multiple applications. However, given its heterogeneous and rigid structure, its efficient conversion to value-added products remains one of the most important limiting factors for the successful viability of the biobased economy. Hydrotreating and hydrothermal treatment (including liquefaction, gasification and wet oxidation) are promising technologies that can convert lignin into biobased products. This review article provides a literature overview of how key process parameters of hydrotreating and hydrothermal treatment (operating conditions, catalysts, solvents, type of starting lignin) may influence the conversion of alkaline lignin into valuable chemical products. It was observed that low selectivity to products (and subsequent required separation and purification) and char formation are the main hurdles for effective conversion of alkaline lignin. However, experimental work in alternative catalytic systems, solvents and hydrogen sources has shown that promising opportunities exist to overcome these drawbacks. Certain catalysts (e.g. Ru/Al2O3) have been found to improve selectivity and the use of alcohol solvents (especially methanol or ethanol) as a hydrogen source has been found to improve product yields and reduce char formation at lower working temperatures and pressures.

Original languageEnglish
Pages (from-to)257-270
Number of pages14
JournalJournal of Chemical Technology and Biotechnology
Volume92
Issue number2
DOIs
Publication statusPublished - Feb 2017

Keywords

  • Alkaline
  • Hydrothermal treatment
  • Hydrotreating
  • Kraft
  • Lignin conversion
  • Lignocellulosic biorefinery

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