Studies on artificial coal. 3. Polycondensates from aromatic hydrocarbons

Abstract

Artificial coals (AC) or coal-like model substances were prepared by the polycondensation of polynuclear hydrocarbons. Anthracene and pyrene gave caking models while phenanthrene (under severe conditions) produced a non-caking model substance. These polycondensates were subjected to solvolysis, thermosolvolysis, thermogravimetry, Gieseler plastometry and differential thermal analysis. The principal conclusions drawn are: 1. (1) The role of the starting aromatic hydrocarbon in deciding the nature of the polycondensate was important for a given set of conditions of polycondensation. 2. (2) The three models behaved differently in yields of chloroform extract by soxhlet extraction: 35.7% (anthracene) and only 0.9% (pyrene), and 3% (non-caking, phenanthrene). Also, in solvolysis and thermosolvolysis the anthracene model behaved like the caking AC and the phenanthrene model behaved like the non-caking AC prepared by hydrothermal carbonification. The preheating of all these models except that from pyrene caused a progressive fall in the subsequent yield of chloroform extract, unlike the other models or AC but like natural caking coal. 3. (3) The anthracene and pyrene models had strikingly high maximum fluidity (>27 000 dial div./min), thus resembling the highly fluid sawdust AC. They also showed low softening temperatures. The stability of chloroform extract as shown by the thermosolvolysis studies was found to be of greater significance than the maximum fluidity or the characteristic Gieseler temperatures in correlating with the caking properties of coal models. 4. (4) Thermograms of these models displayed predominantly exothermic behaviour during pyrolysis, as with other AC and natural coals.