Pyrite-catalysed coal liquefaction using quinoline/tetrahydroquinoline as an H-donor system

Pyrite catalyses the hydrogénation of the N-containing ring in quinoline (Q) to form the active H-donor, 1,2,3,4-tetrahydroquinoline, (THQ). THQ is shown to dissolve coal readily at 325 °C, a temperature lower than that commonly used in most liquefaction processes. Pyrite is effective for maintaining the H-donor capacity of the solvent by hydrogenating the Q formed after H-donation, thereby providing the high THQ/Q required for sustained operation. Qualitative observations suggest that some source of hydrogen, either molecular or donor, must be present to prevent retrogressive reactions of coal fragments.