Effect of TEMPO and characterization of bio-oil from cellulose liquefaction in supercritical ethanol

Cellulose liquefaction in supercritical ethanol with 2,2,6,6-Tetramethylpiperidinooxy (TEMPO) was carried out in a stainless autoclave. The influence of process parameters on bio-oil (BO) and platform chemicals, mainly including the dosage of TEMPO, reaction temperature and reaction time, were investigated. Characterization of liquefaction products was explored by fourier transform infrared (FTIR) and gas chromatography-mass spectrometry analysis (GC-MS). The maximum yield of BO (57.98%) was obtained from cellulose liquefaction at 320 degrees C, 4 g TEMPO and moderate time of 60 min. It showed that the conversion rate and yield of BO was significantly improved by 46.14% and 31.87% due to temperature and TEMPO respectively. The relative contents of dominant platform chemicals in bio-oil were as follows approximately: ketones > esters > alkanes > alcohols > acids. The total yields of ketones enhanced markedly (from 20.00 to 41.83%) with the increasing of TEMPO. The results showed that TEMPO catalyst under appropriate reaction conditions improved the selectivity of platform chemicals with carbonyl, which had an obvious contribution on the converting of ketones. (c) 2019 Elsevier Ltd. All rights reserved.