Energy & Fuels, Vol.23, 1888-1895, 2009
Structural Characteristics and Gasification Reactivity of Chars Prepared from K2CO3 Mixed HyperCoals and Coals
HyperCoal is a clean coal with mineral matter content <0.05 wt %. Oaky Creek (C = 82%), and Pasir (C = 68%) coals were subjected to solvent extraction method to prepare Oaky Creek HyperCoal, and Pasir HyperCoal. Experiments were carried out to compare the gasification reactivity of HyperCoals and parent raw coals with 20, 40, 50 and 60% K2CO3 as a catalyst at 600, 650, 700, and 775 degrees C with steam. Gasification rates of coals and HyperCoals were strongly influenced by the temperature and catalyst loading. Catalytic steam gasification of HyperCoal chars was found to be chemical reaction controlled in the 600 similar to 700 degrees C temperature range for all catalyst loadings. Gasification rates of HyperCoal chars were found to be always higher than parent coals at any given temperature for all catalyst loadings. However, X-ray diffraction results showed that the microstructures of chars prepared from coals and HyperCoals were similar. Results from nuclear magnetic resonance spectroscopy show no significant difference between the chemical compositions of the chars. Significant differences were observed from scanning electron microscopy images, which showed that the chars from HyperCoals had coral-reef like structures whereas dense chars were observed for coals.