The river red gum is a native Australian eucalypt used primarily as a construction material. The wood waste generated during processing of this species has a potential use as feed material for pyrolysis to produce sustainable oils, gases and charcoals. The aim of this study is to investigate the thermal properties of red gum wood under pyrolysis conditions and characterise the resulting bio-oil, bio-gas and biochar products.
Computer Aided Thermal Analysis was conducted to measure the apparent specific heat and thermal conductivity of red gum during heating to 1000°C, for two different heating rates of 10 and 100 °C/min. Decomposition commenced with endothermic reactions up to 300°C, followed by a series of smaller exothermic reactions up to 500°C.
Gas species evolved during heating at 10 °C/min up to 1000°C were measured using micro gas chromatography. Carbon dioxide and methane were the dominant gases produced below 600°C, with hydrogen being the only significant gas evolved above 600°C.
GC-MS was used to determine the major compounds present in the bio-oil produced during pyrolysis at heating rates of 10 °C/min and 100 °C/min. The oils contained organic acids, phenolic compounds and aromatics, with the results showing that bio-oils derived from different eucalypt species are chemically similar.
Biochar yields were established by employing thermogravimetric technique to measure sample mass loss under the two abovementioned heating rates. The chars produced by pyrolysis of red gum to 500°C and 1000°C were analysed and compared to char properties reported in the literature for other biomass species.