TY - JOUR
T1 - Extraction of Taiheiyo coal with supercritical water-phenol mixtures
AU - Aida, Taku Michael
AU - Sato, Takafumi
AU - Sekiguchi, Gaku
AU - Adschiri, Tadafumi
AU - Arai, Kunio
N1 - Funding Information:
Authors would like to express their thanks to the grant of the Ministry of Education, Science, Culture and Sports for partial financial support. We would also like to thank Idemitu Kosan Co. Ltd for supplying the Taiheiyo coal.
PY - 2002/7/8
Y1 - 2002/7/8
N2 - Taiheiyo Japanese sub-bituminous coal was extracted with supercritical water (SCW) and phenol mixtures at 673 K and at over fluid densities ranging from 0 to 0.5g/cm3. The extraction yield with SCW was 0.55-0.60, but increased with increasing the ratio of phenol to water, showing a maximum of 0.7 at water-phenol ratio of 4.5:0.5 and then decreased to 0.50-0.55 for pure phenol. The main products for the SCW-phenol extraction were bisphenol alkyl compounds, while these compounds could not be detected when SCW was used as the solvent. For elucidating the mechanism of SCW-phenol extractions, reactions between phenol and model compounds of hydrolysis products (formaldehyde, acetone, propionic acid, and 2-propanol) were conducted. In SCW, formaldehyde reacted with phenol to produce polymers, while neither acetone nor propionic acid reacted with phenol. The 2-propanol dehydrated to form propene, which reacted with phenol to form 2-isopropylphenol. The reaction rate increased with increasing water density. In SCW-phenol extraction of coal, phenol seems to inhibit reactions that lead to hydrolysis products or those that might cross-link to form the macromolecules. Phenol can be used with SCW to reduce retrograde reactions in residual coals.
AB - Taiheiyo Japanese sub-bituminous coal was extracted with supercritical water (SCW) and phenol mixtures at 673 K and at over fluid densities ranging from 0 to 0.5g/cm3. The extraction yield with SCW was 0.55-0.60, but increased with increasing the ratio of phenol to water, showing a maximum of 0.7 at water-phenol ratio of 4.5:0.5 and then decreased to 0.50-0.55 for pure phenol. The main products for the SCW-phenol extraction were bisphenol alkyl compounds, while these compounds could not be detected when SCW was used as the solvent. For elucidating the mechanism of SCW-phenol extractions, reactions between phenol and model compounds of hydrolysis products (formaldehyde, acetone, propionic acid, and 2-propanol) were conducted. In SCW, formaldehyde reacted with phenol to produce polymers, while neither acetone nor propionic acid reacted with phenol. The 2-propanol dehydrated to form propene, which reacted with phenol to form 2-isopropylphenol. The reaction rate increased with increasing water density. In SCW-phenol extraction of coal, phenol seems to inhibit reactions that lead to hydrolysis products or those that might cross-link to form the macromolecules. Phenol can be used with SCW to reduce retrograde reactions in residual coals.
KW - Coal extraction
KW - Phenol
KW - Supercritical water
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U2 - 10.1016/S0016-2361(02)00067-4
DO - 10.1016/S0016-2361(02)00067-4
M3 - Article
AN - SCOPUS:0037043113
SN - 0016-2361
VL - 81
SP - 1453
EP - 1461
JO - Fuel
JF - Fuel
IS - 11-12
ER -