Enhancement of bio-oil production via pyrolysis of wood biomass by pretreatment with H2SO4

In this work, a Japanese cedar wood sample was treated during the first step at ambient temperature and atmospheric pressure using several concentrations of sulfuric acid (H2SO4) in a stirred flask. During this pretreatment C-O bonds of cellulose, hemicellulose, and lignin were cleaved. The second step involved the pyrolysis of the pretreated wood sample at 550 °C in a quartz glass tube reactor. A maximum oil yield of 46.8 wt% with the minimum char yield of 10.1 wt% was obtained by the treatment with 3 M H2SO4, whereas untreated wood samples resulted in a 30.1 wt% yield of oil. The main components in the oils were levoglucosan and tar. These results suggest that moderate acid pretreatment produced shorter chain units of cellulose, hemicellulose, and lignin, thereby facilitating the conversion into oil by pyrolysis. The results of thermogravimetry-mass spectroscopy supported the presence of shorter chain units in the pretreated wood samples.