Cracking and hydrogen transfer activities of highly dispersed iron catalysts for coal liquefaction

摘要

Activities in cracking and hydrogen transfer of several iron catalysts for coal liquefaction were evaluated quantitatively by the measurement of the liquid-phase cracking rate of dibenzyl using a small autoclave at 420 and 440°C in the presence of tetralin or decalin under hydrogen or nitrogen atmosphere. Remarkable increase in rate constant was observed at 420°C using sulfided iron oxide catalyst under high pressure of hydrogen in the presence of decalin, in comparison with the data obtained in the presence of tetralin and in the thermal reaction. This indicates sulfided iron oxide shows cracking activity for catalytic C-C bond cleavage of dibenzyl under these conditions. The liquefaction of Japanese subbituminous coal (Taiheiyo coal) in the presence of decalin at 420°C under initial hydrogen pressure of 5MPa for 1 hr showed 89 wt%, daf of the conversion, which was almost comparable to 91 wt%, daf with tetralin. However, under lower initial hydrogen pressure of 2MPa for 3 hr, lower conversion of 64 wt%, daf with decalin than that of 94 wt%, daf with tetralin was observed. This suggests that the cracking activity of sulfided iron oxide catalyst is accelerated in the presence of decalin and high pressure of hydrogen at 420°C.