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This study focuses on the effects of interactions among bio-oil components on the formation of aromatic structures of bio-oil during its thermal treatment processes at various temperatures and heating rates. A bio-oil sample and its extracted fractions were pyrolyzed in a fixed-bed reactor at 300–800 °C at different temperatures and heating rates. The results show that the pyrolytic products (including...
The main components in bio-oil behave differently during the thermal treatment in water or in methanol. Water cannot stabilize the aromatics in bio-oil. Consumption of the aromatics with mono-ring and two fused benzene rings and the formation of the aromatics with three or more fused benzene ring aromatics were observed during the thermal treatment in water. In methanol, the fluorescence intensities...
The different catalytic behaviour of solid acid catalyst and mineral acid catalyst towards the acid-treatment of bio-oil was investigated. The hydrogen ions in the mineral acid catalyst such as sulfuric acid homogeneously dispersed in the reaction medium made the conversion of main components of bio-oil including carboxylic acids, sugars and phenolics more efficient. In comparison, there was a steric...
This study aims to investigate the importance of steam to tar destruction during the volatile–char interactions. Steam was supplied in the absence and presence of nascent char during the pyrolysis/gasification of biomass at 850°C. In the absence of char, steam has more significant effects on the reforming of large aromatic ring systems (e.g. >2 fused benzene rings) than small and isolated aromatics...
In this study, acid-catalyzed conversions of three typical C6 sugar monomers/oligomers (glucose, maltose, and beta-cyclodextrins) to levulinic acid in water, tetrahydrofuran (THF) and toluene have been investigated over a solid acid catalyst Amberlyst 70 (A70), aiming to understand behaviors of the sugars in the solvents with distinct polarities. Molecular sizes of the sugars do not affect both insoluble...
This study aims to investigate the roles of char in the in situ destruction of tar during the volatile–char interactions. Rice straw and water/acid-washed rice straw samples were pyrolysed at 850°C with controlled extents of volatile–char interactions in a fluidised-bed/fixed-bed reactor. Our results indicate that the amount of tar decreases significantly with increasing extent of volatile–char interactions...
This study has investigated the hydrotreatment of bio-oil (derived from the fast pyrolysis of mallee woody biomass) in a batch reactor under 10MPa pressure with Pd/C catalyst at temperatures between 150°C and 300°C. Our results indicate that the chemical fractions, coking tendency as well as the aromatic structures are highly influenced by the hydrotreating conditions such as temperature and time...
In this study a non-aqueous potentiometric titration method has been developed to quantify the carboxylic acids and phenolics in bio-oil. Quarternary ammonium hydroxide was used as the titrant and a mixture of tert-butanol and acetone was used as the solvent to differentiate the acidic components with distinct acidities. The heavy carboxylic acids, which cannot be identified with GC–MS, account for...
This study has investigated the observed product distribution as a function of temperature and liquid hourly space velocity (LHSV) from the continuous hydrotreatment of pyrolysis bio-oil in a packed-bed catalytic reactor using a Pd/C catalyst. Our results show that, at a constant overall LHSV value, the time required to achieve a steady state formation rate varies widely among the various species...
Bio-oil cannot be directly used as biofuel mainly due to its abundant oxygen-containing functional groups. Therefore, bio-oil must be upgraded to produce high quality biofuels. As the first part of this series, this paper reports the transformation of GC-detectable light components during the hydrotreatment of bio-oil using noble-metal catalyst Pd/C over a wide range of reaction temperature (150–300°C)...
Steam reforming of bio-oils is a viable way to produce syngas, but certain challenges need to be overcome before its commercial application. One of the main issues is the formation of tar and coke. Investigation of the evolution/formation of aromatic structures in steam reforming is an effective way to understand the mechanism of tar/coke formation. In this study, the pyrolysis, steam reforming and...
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...
Bio-oil from the pyrolysis of biomass can be upgraded into high quality liquid biofuels or utilised as a feedstock to boilers and gasifiers. The coke formation is a particularly serious problem for the upgrading of bio-oil as well as the direct utilisation of bio-oil. The effects of bio-oil chemical composition on the coke formation are keys to the understanding of the mechanism of coke formation...
This paper reports the acid-catalysed reactions between methanol and the bio-oil from the fast pyrolysis of mallee bark. The study focused on the reactions of the fatty acids, esters, furans and anhydrosugars in the bio-oil with methanol at 70–170°C in the presence of a solid acid catalyst Amberlyst 70. Under the experimental conditions employed, both simple acids and fatty acids in bio-oil could...
Acid-catalysed esterification converts organic acids in bio-oil into useful esters. However, the conditions to carry out esterification also promote the hydrolysis of anhydro-sugars in bio-oil. This paper reports the hydrolysis and glycosidation of sugars during the esterification of bio-oil using Amberlyst-70 solid acid catalyst at 70–170°C. The bio-oil was prepared from the fast pyrolysis of mallee...
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