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Liquid-phase reforming and hydrodeoxygenation as a two-step route to aromatics from lignin

By A.L. Jongerius, P.C.A. Bruijnincx and B.M. Weckhuysen

Abstract

A two-step approach to the conversion of organosolv, kraft and sugarcane bagasse lignin to monoaromatic\ud compounds of low oxygen content is presented. The first step consists of lignin depolymerization\ud in a liquid phase reforming (LPR) reaction over a 1 wt% Pt/γ-Al2O3 catalyst at 225 °C in alkaline ethanol–\ud water. The first LPR step resulted in a decrease in lignin molecular weight of 32%, 57% and 27% for organosolv,\ud kraft and bagasse lignin, respectively. GC analysis of the depolymerized lignin reaction mixture\ud furthermore showed the formation of alkylated phenol, guaiacol and syringol-type products in 11%, 9%\ud and 5% yields from organosolv, kraft and bagasse lignin, respectively. The lignin-oil that was isolated by\ud extraction of the ethanol–water solution was subjected to a subsequent hydrodeoxygenation (HDO)\ud reaction in the second conversion step. HDO of the lignin-oil was performed in dodecane at 300 °C\ud under 50 bar hydrogen pressure over CoMo/Al2O3 and Mo2C/CNF catalysts. GC analysis of the product\ud mixture obtained after the two-step LPR–HDO process revealed the formation of, amongst others,\ud benzene, toluene, xylenes and ethylmethylbenzenes. Of the total observed monomeric products (9%),\ud 25% consisted of these oxygen-free products. Notably, such products cannot be obtained by direct HDO\ud of lignin. HDO of the lignin-oil at 350 °C resulted in the conversion of all tris-oxygenated products, with\ud 57% of the observed monomeric products now identified as mono-oxygenated phenolics

Topics: Aardwetenschappen, Scheikunde, Scheikunde
Year: 2013
OAI identifier: oai:dspace.library.uu.nl:1874/290650
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