Catalytic hydrotreatment of pyrolytic lignins to give alkylphenolics and aromatics using a supported Ru catalyst

Abstract

The catalytic hydrotreatment of two pyrolytic lignins (pine and forestry residue), obtained from the corresponding fast pyrolysis oils, and organosolv Alcell lignin as a benchmark was explored in a batch set-up using Ru/C as the catalyst (400 °C, 4 h, 100 bar initial H₂ pressure). The highest lignin oil yield was obtained for forest residue pyrolytic lignin (>75 wt% on intake). Advanced GCxGC techniques in combination with GPC and ¹³C-NMR measurements indicate that the lignin oils contain high amounts of interesting monomeric chemicals like alkylphenolics (up to 20.5 wt% on lignin feed intake) and aromatics (up to 14.1 wt% on lignin feed intake). These values are considerably higher than for Alcell lignin (6.6 wt% alkylphenolics and 9.7 wt% aromatics) and clearly indicate that pyrolytic lignins have potential to be used as feeds for the production of biobased phenolics and aromatics.