Almost complete dissolution of woody biomass with tetra-n-butylphosphonium hydroxide aqueous solution at 60 °C

Abstract

Dissolution of several kinds of woods was examined in tetra-n-butylphosphonium hydroxide ([P_4,4,4,4]OH) aqueous solution. Since there is a strong correlation between the dissolution degrees and the Klason lignin contents of the wood, lignin degradation and removal were found to be necessary for efficient dissolution of several woods such as cedar. It was found that moderate heating (60 °C) and addition of H₂O₂ aqueous solution to 50% [P_4,4,4,4]OH aqueous solution are quite effective to dissolve wood. Cedar powder (final concentration of 5.0 wt%) was almost completely dissolved in this aqueous solution at 60 °C under mild stirring for 24 h. This efficient wood dissolution was caused by partial degradation of lignin.