Differential thermal analysis study of lignite hydrogenation

Abstract Several New Zealand lignites and three other coals have been compared by differential thermal analysis in hydrogen at a pressure of 8.0 MPa. Most coals showed two exothermic peaks at ≈350 and 500 °C, but the relative magnitude of the two peaks varied from one coal to another. Ion-exchanging one of the lignites with Zn, Fe, Ni, Pb and Sn reduced the temperature of the peak maximum. Both Fe and Sn are known to catalyse coal hydrogenation. The results show that nickel and lead warrant further investigation as potential catalysts for coal hydroliquefaction, since they reduced the reaction temperatures even more than Fe or Sn. The reaction of lignite with tetrahydronaphthalene, in the absence of hydrogen, has been shown to be endothermic; a factor of interest in the context of donorsolvent hydroliquefaction facilities.