• Energy Research
• 15. Life on land close

Abstract Bio-oil contains organics with the potential application as liquid fuels for use in vehicles via upgrading. Nevertheless, the applications of bio-oil depend on its properties, which are further indicated by the origin of the biomass feedstock, pyrolysis conditions and configuration of pyrolysers. It of importance of establishing the correlation between the properties of biomass and features of corresponding bio-oil formed, the bio-oils obtained from 20 types of biomasses ranging from different woods, agriculture wastes including various grass types and other biomasses including coconut shell, etc were studied. The features of bio-oils were compared and correlated with the features of the biomasses. The results indicated that the relative proportions of the subcomponents of biomass had significant impacts on the distribution of the species produced. For woody biomass, cellulose and hemicellulose could have more contribution to the formation of the gas. Effects of the subcomponents in biomass on the formation of bio-oil and biochar were very complicated, and it was difficult to establish direct correlation between lignin content and char yield. Nevertheless, the inorganic species in biomass catalyzed charring reactions, leading to the biochar formation increase while the decreased production of bio-oil. Other factors such as mass transfer limitations, heat transfer and especially biological structures of biomass also influenced the products. Comparing with woody biomass, higher yields of gaseous products and biochar with correspondingly lower bio-oil yields was produced from the herbaceous biomass, relating to the high ash content and the distinct biological structure of herbaceous biomass.

Abstract Bark constitutes an important part of any woody biomass to be used for the production of second generation biofuels and chemicals. Pyrolysis followed by biorefinery is a promising technology for the efficient utilisation of all components from a woody crop. While significant efforts have been devoted to the investigation of the pyrolysis characteristics of wood, relatively less is known about the pyrolysis behaviour of bark. This study aims to clarify the effects of temperature on the yields and composition of bio-oil from the pyrolysis of eucalypts bark. The bark of mallee, a type of eucalypt grown for soil amendment in Western Australia, was pyrolysed between 300 and 580 °C at fast heating rates in a fluidised-bed pyrolysis unit. The bio-oil liquid products separate into two phases. The bio-oil liquid products were analysed by GC–MS, Karl-Fischer titration, UV-fluorescence spectroscopy, ICP-OES and thermogravimetric analysis (TGA). These results are compared, when appropriate, to those obtained from the wood fraction.

Biochar is widely considered as a soil amendment. This study aims to investigate the leaching of macronutrients (K, Mg and Ca) and organics from biochars produced from mallee biomass (wood, leaf, bark) in a fluidised-bed pyrolyser at 500 °C. Biochars were soaked in solutions of varying pH values and shaken for a pre-set period of time ranging from 1 h to 4 weeks. The initial pH values of the leaching solutions used (3.4, 5.5, 7 and 8.5) covered the pH range of the soils in the Wheatbelt region of Western Australia (WA). For these bark, leaf and wood biochars, we can conclude that the biochars have a liming capacity for the acid soils of the WA Wheatbelt, depending on the feedstock. The maximum leachabilities and leaching kinetics of the macronutrients K, Mg and Ca depend on the pH of the solution in which biochar was soaked. Apparently, Ca, K and Mg in biomass are converted into different species upon pyrolysis, and the biomass species are critical for the extent of the leachability of macronutrients. Further, the chemical form of each nutrient retained in the biochars will dictate the kinetics as a function of soil pH. This study's GC/MS analysis of solvent extraction of the biochars showed potential toxicity due to the leaching of light organic compounds when biochars are added to soils. Furthermore, this study also showed the influence of pH on the leaching of large aromatic organics from the biochars. Apart from the pH of leaching solution, the influence of the biomass feedstock on the leaching kinetics of large aromatic organics from biochars was demonstrated. These leached aromatic organics were characterised by UV-fluorescence spectroscopy.