The use of various metal carbonyls as catalyst precursors for coal hydroliquefaction

The catalytic activity of metal carbonyl complexes of chromium, molybdenum, tungsten, manganese, iron, cobalt, and nickel in the liquefaction of coal (Illinois No. 6, Wandoan and Mi-ike) was investigated. The carbonyl compounds of molybdenum, tungsten, iron, cobalt, and nickel acted as highly active catalysts for the liquefaction of Illinois No. 6 coal, resulting in high coal conversion (>90%) and high oil yield (>32%), under hydrogen pressure of 50 kg cm^?1 in a nonhydrogen-donating solvent at 425°C for 60 min. Among the catalysts surveyed, Mo(CO)₆ gave the highest oil yield (57.7%) and the largest amount of hydrogen transferred to coal (3.1 wt.% of d.a.f. coal). However, the molybdenum and tungsten carbonyls did not exhibit high catalytic activity for low sulfur Wandoan coal in the absence of added sulfur. On the other hand, cobalt and nickel carbonyls showed high catalytic activity irrespective of the amount of sulfur in the reaction system. Fe(CO)₅Mo(CO)₆ binary catalyst promoted hydroliquefaction of Wandoan coal, resulting in increases in oil yield and transfer of hydrogen to coal in the presence of sulfur.