Conversion of bituminous coal in COH2O systems: 3. Soluble metal catalysis

The oxyanions of the highest oxidation states of several transition metals, including W, Mo, Cr and Mn, were found to catalyse the liquefaction of Illinois No. 6 coal in $\text{CO}\text{H}{}_2\text{O}$ systems at 400°C. Unlike the high pH (s> 12) required in the base-catalysed system, the effective range for these metal-mediated conversions extend down to pH < 5.0. The benzene-soluble product was found to have a higher $\text{H}\text{C}$ ratio than the starting coal, and the metals were reduced to water-insoluble, lower oxidation states during conversion. A chain scheme is suggested as an explanation for the data.