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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...
This study aims to investigate the changes in char structure during the pyrolysis in N2 and subsequent gasification in air at low temperature in a thermogravimetric analyser. The chars produced from the gasification of Loy Yang brown coal in 15% H2O balanced with CO2 at 850 °C in a fluidised-bed/fixed-bed reactor were used in this work. The evolution of char structure during pyrolysis and in-situ...
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 structural features of nascent char. Two nascent chars were prepared from the pyrolysis of Loy Yang brown coal and Collie sub-bituminous coal in a wire-mesh reactor by heating at 1000Ks−1 to 600°C. Structural changes in nascent chars were investigated by reheating the chars in N2 at low temperatures (≤600°C) followed by subsequent gasification in O2/N2 mixtures at...
This study is focused on the effects of char structure and alkali and alkaline earth metallic (AAEM) species on the changes in char-O2 reactivity for a Western Australian Collie sub-bituminous coal. The char samples used in this study were acquired from the partial gasification of the sub-bituminous coal in a fluidised-bed/fixed-bed reactor in pure CO2, 15% H2O balanced with Ar and a mixture of 15%...
Char is used directly as a catalyst for the catalytic reforming of tar during gasification. Experiments have been carried out to examine the effects of inorganics in char as a catalyst for the catalytic reforming of tar during the gasification of mallee wood, corn stalk and wheat straw in a pilot plant. The char catalyst was prepared from the pyrolysis of mallee wood at a fast heating rate. The catalytic...
The purpose of this study is to investigate the structural changes in nascent chars during the gasification of two low-rank coals in CO2 at 1000°C and 1200°C. Western Australian Collie sub-bituminous coal and Victorian Loy Yang brown coal were heated up at 1000Ks−1 in He/CO2 in a wire-mesh reactor. FT-Raman spectroscopy was applied to understand the key structural features of nascent chars. For comparison,...
The structural evolution of nascent chars during the fast pyrolysis of a wood and two low-rank coals was investigated in this study. Western Australian Collie sub-bituminous coal, Victorian Loy Yang brown coal and Western Australian mallee wood were pyrolysed in a wire-mesh reactor that is capable of providing rapid heating rates (up to 5000Ks−1) and accurate holding time (in increments of 10ms) at...
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...
This paper reports an experimental study to assess the effects of CO 2 and heating rate on the characteristics of the chars formed in CO 2 and N 2 atmospheres in the initial stage of oxy-fuel combustion. The chars of a Chinese bituminous coal were prepared in a fluidised-bed/fixed-bed reactor at 900°C and their chemical structural features were further characterised with FT-Raman...
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...
How a catalyst would speed up gasification is fundamentally important for the development of efficient gasification technologies. It is particularly crucial for the efficient use of catalytic species inherently present in low-rank coal and biomass. This study aims to gain insights about the catalytic gasification reaction mechanisms through tracing the changes in char structure during gasification...
Char structure is one of the important factors influencing the char reactivity during gasification. The purpose of this study is to investigate the effects of gasification atmosphere and temperature on the changes of char structure during gasification. In this study, a Collie sub-bituminous coal from Western Australia was gasified in a fluidised-bed/fixed-bed reactor at 800–900°C in three gasification...
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...
A char-supported iron catalyst was investigated as a catalyst for destructing the NO x precursors (e.g. HCN and NH 3 ) during the catalytic steam reforming of tar derived from the pyrolysis of mallee bark and leaf. It was found that the H-form char as a catalyst exhibited little activity for destructing NO x precursors even at high temperature, while on the contrary NO ...
Hydrogen as a gasification product gas is always present in a practical gasifier. Its inhibition of char gasification is always an important consideration in the design and operation of the gasifier. This study aims to provide further insights into the roles of hydrogen during gasification by characterising the chars at varying levels of conversion using FT-Raman spectroscopy. The char samples were...
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...
Volatile–char interactions are an important phenomenon in almost all existing gasification processes. The volatile–char interactions can very significantly affect almost every aspect of low-rank fuel gasification, including the volatilisation of alkali and alkaline earth metallic species that are inherent catalysts for gasification, the evolution of char structure, the dispersion of inherent catalysts...
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