Kinetic modelling of low temperature direct coal liquefaction: Consideration of dynamic catalyst activity

A kinetic model for direct coal liquefaction at low temperature in the presence of a magnetite nano-catalyst was developed. The model took into account the iron oxide catalyst transformation into its active state as well as the process of reactive dissolution of coal at the reduced temperatures. The validity of the model was tested by performing a regression on experimentally obtained data for the direct coal liquefaction process. The experiments were performed in a high-pressure batch reactor, with medium to low ranking coal, using synthesised magnetite nano-catalysts and within the temperature range of 240 ◦C to 320 ◦C. This temperature range is known to be below that required for thermolysis of the coal. The model was able to qualitatively capture the general trends of the experimental data. The regression indicated that the depolymerisation reactions of the dissolved moieties directly into key products occur more rapidly than the reactions of key product groups, which is a typical occurrence in lower rank coals. (author)