DIRECT HYDROLIQUEFACTION OF A LOW-RANK SOFT BROWN-COAL

The behaviour of the soft brown coal from the Kostolac Mine (Serbia, Y ugoslavia) was investigated during hydroliquefaction carried out in a batch reactor by direct catalytic hydrogenation of the pulverized coal (-160 mu m) dispersed in tetralin. The effects of temperature (rangin g from 365 to 440 degrees C), pressure (13.5 to 15.0 MPa) and residenc e time (1 to 8 h) on the yield of individual liquefaction products as well as the petrographic composition of the coal residues were closely followed by separation and analysis of the products. These consisted of liquid products soluble in n-heptane (light oils), n-heptane insolu ble products (asphaltenes), the solid coal residue and gaseous product s. A good reactivity of this soft brown coal was observed. The yield o f liquid products varied from 23 to 64 wt.% (based on dry ash-free coa l). A total coal conversion of 80 to 86% was achieved. Petrographic co mposition and optical properties of the solid coal residues were analy zed microscopically in order to establish the character and intensity of the coal changes. The solid residues were found to consist of 12 va rious grain categories. The low proportions of unreacted or partly rea cted coal grains confirmed the good reactivity of the Kostolac soft br own coal in the applied liquefaction process. (C) 1998 Elsevier Scienc e B.V. All rights reserved.