Production of bio-oil and bio-char from pyrolysis of sawdust wood waste (SWW)

Abstract

This study deals with fast pyrolysis of sawdust wood waste (SWW) at the range of temperature 300–700 °C in a stainless steel tubular reactor. The aim was to experimentally investigate how the temperature, the particle size, the nitrogen flow rate (N2) and the heating rate affect bio-oil, bio-char and gaseous products. These parameters were varied in the ranges of 5–20 °C/min, below 0.1–1.5 mm and 20–200 mL min−1, respectively. It was concluded that both the temperature and heating rate have a significant effect on both yield of bio-oil and bio-char resulting from pyrolysis of SWW. The liquid products obtained at various pyrolysis temperatures were subjected into column chromatography after removal of asphaltenes (hexane insoluble). Obtained bio-oils (maltenes or hexane soluble) were classified as aliphatic, aromatic and polar sub-fractions. The maximum of bio-oil yield of 39.5 wt% was obtained at a pyrolysis temperature of 500 °C, particle size between 0.5 and 1 mm, nitrogen flow rate (N2) of 100 mL min−1 and heating rate of 5 °C/min. Liquid product (bio-oil) obtained under the most suitable and optimal condition was characterized by elemental analysis, Nuclear magnetic resonance spectroscopy (1H NMR and 13C NMR), Fourier transformed infrared spectroscopy (FT-IR). The analysis of liquid showed that bio-oil from SWW could be a potential source of renewable fuel production and value added chemical. The yield of char generally decreases with increasing the temperature, the char yield passes from 54.61 to 29.47 wt% at the heating rate of 5 °C/min and from 50.01 to 24.5 wt% at the heating rate of 20 °C/min at the same range of temperature (300–700 °C). Solid products (bio-char) obtained in the presence of nitrogen (N2) contain a very important percentage of carbon and high heating values (HHVs).