The effect of temperature on the catalytic conversion of Kraft lignin using near-critical water.

Thi Dieu Huyen Nguyen, Marco Maschietti, Lars-Erik Åmand, Lennart Vamling, Lars Olausson, Sven-Ingvar Andersson, Hans Theliander

Index: Bioresour. Technol. 170 , 196-203, (2014)

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Abstract

The catalytic conversion of suspended LignoBoost Kraft lignin was performed in near-critical water using ZrO2/K2CO3 as the catalytic system and phenol as the co-solvent and char suppressing agent. The reaction temperature was varied from 290 to 370°C and its effect on the process was investigated in a continuous flow (1kg/h). The yields of water-soluble organics (WSO), bio-oil and char (dry lignin basis) were in the ranges of 5-11%, 69-87% and 16-22%, respectively. The bio-oil, being partially deoxygenated, exhibited higher carbon content and heat value, but lower sulphur content than lignin. The main 1-ring aromatics (in WSO and diethylether-soluble bio-oil) were anisoles, alkylphenols, catechols and guaiacols. The results show that increasing temperature increases the yield of 1-ring aromatics remarkably, while it increases the formation of char moderately. An increase in the yields of anisoles, alkylphenols and catechols, together with a decrease in the yield of guaiacols, was also observed. Copyright © 2014. Published by Elsevier Ltd.