Hydrogenation of Yubari coal using "chromium oxide catalysts".

“Chromium oxide catalysts” consisting of Cr, O and C were pre-pared from the addition compounds that were easily formed with CrO3 and phenols in aqueous solution. The catalytic activities of various chromium oxides were examined for the direct liquefaction of Yubari coal. The rate constants obtained from these reactions showed two different values with reaction time. At reaction time between O and 2 hours, it was 8.9×10-3min-1 which showed a value five times larger than that for parent coal. Main products were benzene solubles (BS) and hexane solubles (HS). At reaction time of 2h and above, it was 8.5×10-4min-1 and remarkably depressed. These results showed that the hydrocracking of coal largely ceased in the initial stage. But main product, HS increased with time. Therefore, hydrogenation of BS would occur after 2h. Conversion was only 40% of coal without catalyst. However, 90% conversion was achieved with catalysts of 12wt%. Thus, it is consi-dered that the catalytic activities depend on both relative ratio of constituent atoms and structure of chromium oxide.