Effect of mobile phase properties and macromolecular network reactivity on liquefaction behavior of bituminous coals

Abstract

The effects of quantity of mobile phase, viscosity of mobile phase, and network reactivity were evaluated on the liquefaction conversion of four coals. Reactions were carried out at 275°C for 10 and 30 minutes, and in a temperature-staged configuration for 30 minutes each at 275 and 425°C. Coals were impregnated with a sulfided ammonium molybdate catalyst. If all other factors were held reasonably comparable, it was found that a coal having lower viscosity mobile phase produced higher conversions at 275°C than a similar coal having a more viscous mobile phase. This effect is attributed to easier transport of the mobile phase from the interior of a coal particle to the catalyst on the particle's surface. For coals having comparable viscosities of mobile phase and comparable network reactivities, the coal having the greater quantity of mobile phase produced higher conversions. When network reactivity was the principal difference, the coal having the less reactive network resulted in lower conversion. Thus for good liquefaction conversions at relatively mild conditions, a coal having a large amount of fluid (low viscosity) mobile phase and a reactive network is desirable. These differences among coals are much less apparent in temperature-staged liquefaction; the much more severe reaction conditions appear to overwhelm the subtle differences of mobile phase and network properties.