A study on the molybdenum-catalyzed hydrogenation of coals in the absence of solvent

Insight into the structure of coal and mechanisms of liquefaction was obtained by reacting hydrogen gas with coal in the absence of solvent and in the presence of an impregnated molybdenum catalyst under conditions of low severity. The compositions and yields of gaseous products, chloroform-soluble extracts, and unextracted residues were followed under various reaction conditions, and characterized by conventional chemical and physical techniques.;For a bituminous and subbituminous coal, the process of catalytic hydrogenation was found to proceed through two distinct regimes of liquefaction characterized by low and high yields of soluble products. At low yields the soluble products contained a high proportion of oils. On going to higher liquids yield, the proportion of oils in the extracts passed through a minimum and then increased. Based on elemental and ;Liquefaction conducted in stages of increasing severity (temperature-staged liquefaction) has been shown to improve conversion and product distribution for both a subbituminous and a bituminous coal. In addition, it was found that the low-rank coal was more reactive during temperature-staged liquefaction than a bituminous coal. It is considered that the higher reactivity of the low-rank coal is attributable to the initial reactions being conducted under conditions which promote hydrogenation while minimizing condensation and cracking reactions.