Physico-Chemical Properties of Bio-Oils from Pyrolysis of Lignocellulosic Biomass with High and Slow Heating Rate

摘要

Bio-oil is a major product of biomass pyrolysis that could potentially be used in motor engines, boilers, furnaces and turbines for heat and power. Upon catalytic upgrading, bio-oils can be used as transportation fuels due to enhancement of their fuel properties. In this study, bio-oils produced from lignocellulosic biomasses such as wheat straw, timothy grass and pinewood were estimated through slow and high heating rate pyrolysis at 450 ℃. The slow heating rate (2 ℃/min) pyrolysis resulted in low bio-oil yields and high amount of biochars, whereas the high heating rate (450 ℃/min) pyrolysis produced significant amount of bio-oils with reduced biochar yields. The physico-chemical and compositional analyses of bio-oils were achieved through carbon-hydrogen-nitrogen-sulfur (CHNS) studies, calorific value, Fourier transform-infra red (FT-IR) spectroscopy, gas chromatography-mass spectrometry (GC-MS), electrospray ionization-mass spectrometry (ESI-MS) and nuclear magnetic resonance (NMR) spectroscopy. The yields of bio-oils produced from the three biomasses were 40-48 wt.% through high heating rate pyrolysis and 18-24 wt.% through slow heating rate pyrolysis. The chemical components identified in bio-oils were classified into five major groups such as organic acids, aldehydes, ketones, alcohols and phenols. The percent intensities of hydrogen and carbon containing species were calculated from ~1H and ~(13)C-NMR. The study on bio-oils from herbaceous and woody biomasses revealed their potentials for fossil fuel substitution and bio-chemical production.