An investigation of the coal dissolution phenomena of bituminous coal during the initial stage is reported. The experimental data obtained from pilot plants and laboratory units are analysed. Coal dissolution reactions can be classified into two distinct stages. In the initial stage of coal dissolution, a first-order reaction scheme is proposed, whereby coal undergoes a fast thermal reaction producing preasphaltene as the predominant product. Conversion for this reaction is calculated, based on the amount of pyridine solubles formed. The rate coefficient for this stage is found to follow an Arrhenius type temperature dependence with an activation energy of 200 ≈ 230 kJ/mol. The second stage reaction, characterized by the formation of asphaltene and coal oil, has been discussed elsewhere6.
