Effect of highly dispersed iron catalyst on direct liquefaction of coal

The effect of a highly dispersed gamma-FeOOH catalyst on the liquefaction o f Yallourn coal was examined using a rapid-heating autoclave equipped with an infrared-ray image furnace, in relation to its transformation into pyrrh otite (Fe1-xS), by comparison with a conventional pyrite catalyst. It was f ound that the gamma-FeOOH catalyst promoted the activation of gaseous hydro gen remarkably during the heating stage up to 450 degrees C, as it could be transformed into smaller size pyrrhotite at lower temperatures of around 2 50 degrees C, As a result, the efficiency of hydrogen consumption on oil yi eld was significantly increased due to a lower yield of hydrocarbon gases, compared with the case where pyrite catalyst was used, Further continuous l iquefaction tests were performed using a 0.1t/d Bench Scale Unit (BSU) with gas and bottom recycling, and the residual activities of the recycle catal ysts in the coal liquid bottom (CLB) were examined using a batch type autoc lave, It appeared that the oil yield increased with a decrease in the cryst allite size of pyrrhotite among the fresh and recycle catalysts, Control of H2S at a concentration of approximately 1.0 vol.% in the gas phase by the addition of elemental sulfur was effective in maintaining the liquefaction activity of recycle catalyst because of the suppression of both troilite fo rmation and the crystal growth of pyrrhotite, It was demonstrated that a hi gh oil yield of over 60wt%daf was obtained in the liquefaction of Yallourn coal with a considerable reduction of gamma-FeOOH catalyst loading. (C) 200 0 Elsevier Science Ltd. All rights reserved.