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Hydrotreating and hydrothermal treatment of alkaline lignin as technological valorization options for future biorefinery concepts: a review
Author(s) -
Rutten Cathelijne,
Ramírez Andrea,
Posada Duque John
Publication year - 2017
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.5103
Subject(s) - biorefinery , lignin , vanillin , hydrodesulfurization , hydrothermal liquefaction , catalysis , chemistry , organic chemistry , chemical engineering , raw material , engineering
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/ Al 2 O 3 ) 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. © 2016 Society of Chemical Industry