HyperCoal (HPC) is ashless coal obtained by a mild thermal extraction of coal to remove unextractable, heavy compounds, and minerals. The temperature and duration of HPC hydrogenation was systematically varied with and without solvent in an autoclave under hydrogen pressure. Unlike raw coal, hydrogenation of HPC in the absence of solvent proceeded without coke formation when the reaction was performed for 60 min at 450 °C in 10 MPa hydrogen (initial pressure). The hydrogenation catalyst was recycled five times with no detection of deactivation. Longer reactions at slightly higher temperatures (120 min at 460 °C), with replenishing the hydrogen, afforded a 90 wt % oil (hexane-soluble fraction) yield.
HyperCoal
(HPC) is an ashless coal produced by thermal solvent
extraction from a coal and is expected to be useful for several utilization
technologies because of it is mineral matter free and high softening
property. Although HPC can be produced from various ranks, HPC extraction
yield from low-rank coals is low due to the influence of hydrogen
bonds among functional groups. Extraction yield can be increased by
using a polar solvent for breaking the hydrogen bonds leading to increased
yield. In this study, the relationship between the extraction yield
by a polar solvent and oxygen functional groups was investigated.
The results showed that the effectiveness of polar solvent increased
with increasing phenolic hydroxyl content and an excellent correlation
between the effectiveness of polar solvent and the phenolic hydroxyl
content in coals was found.
HyperCoal" (HPC) is the ashless coal produced by thermal solvent extraction; the extraction yield is a key factor in HPC production. The extraction yield varies depending upon the properties of the coals and the solvent used. For a wide range of coals, the extraction yields at 360°C have been successfully estimated by a multiple regression analysis, using the values of ultimate and proximate analyses. The equation consists of volatile matter/O% (or O%), C/H, and a function of S%; a correlation coefficient of r = 0.790 was obtained for the extraction yield with 1-methyl-naphthalene (1-MN) for 76 coals. When the polarity of the extraction solvent was increased, the effects of O% decreased, while that of C/H did not change. With regard to coals with an O% less than 8.2, the extraction yield of 1-MN correlated only with the C/H value. These results suggest that the C/H value is the main factor for a high extraction yield.
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