Kraft Lignin Depolymerization in Near-Critical Water: Effect of Changing Co-Solvent
Artikel i vetenskaplig tidskrift, 2014

As part of developing a process to valorize lignin in a pulp mill with lignin separation, the depolymerisation of lignin to valuable chemicals was investigated in near-critical water. This was done by using methanol as co-solvent and hydrogen donor, phenol to suppress repolymerization (e.g. formation of char), and ZrO2 as a heterogeneous catalyst, with potassium carbonate as a co-catalyst. The reaction was carried out in a continuous flow fixed-bed reactor (500 cm(3)), at 280-350 degrees C and 25MPa. An important aspect is to suppress char formation. Therefore, the char formation was studied by using different concentrations of methanol and phenol. The char yield varied between 14% and 26%. When using methanol as the only co-solvent, the char yield decreased with increasing methanol concentration. Adding phenol resulted in a further decrease. The reactor outlet consisted mainly of two liquid phases, an aqueous and an oil phase, mixed together. The chemical analysis of the aqueous phase showed the presence of mainly phenolic compounds, for instance guaiacol, catechol, phenol and cresol.

char formation

near-critical water


lignin conversion

phenolic compound

hydrogen donors


Tallal Belkheiri

Industriella energisystem och tekniker

Lennart Vamling

Industriella energisystem och tekniker

Huyen Nguyen Lyckeskog

Chalmers, Kemi- och bioteknik, Skogsindustriell kemiteknik

Marco Maschietti

Chalmers, Kemi- och bioteknik, Skogsindustriell kemiteknik

L. Olausson


Sven-Ingvar Andersson

Chalmers, Kemi- och bioteknik, Teknisk ytkemi

Lars-Erik Åmand

Industriella energisystem och tekniker

Hans Theliander

Wallenberg Wood Science Center (WWSC)

Chalmers, Kemi- och bioteknik, Skogsindustriell kemiteknik

Cellulose Chemistry and Technology

0576-9787 (ISSN)

Vol. 48 9-10 813-818


Pappers-, massa- och fiberteknik

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