Abstract:
The reaction kinetics of the dissolution of two Turkish lignites have been investigated. The dissolution products were separated into pseudo-components such as preasphaltenes, asphaltenes and oils by successive solvent extractions. Reaction mechanisms have been proposed and tested to estimate the rates of formation of these products. The proposed mechanisms are based on the assumptions that the reactions are irreversible, pseudo-first order with respect to the reacting species, and their rate constants obey linear Arrhenius behavior. The product distributions data have been assessed by a simple simulation program. The results indicated that certain simple kinetic models represent the data well and the prevailing mechanism changes slightly with temperature. The estimated energy of activation for dissolution changes from 54 kJ/gmol to 185 kJ/gmol depending on the lignite and the suggested reaction model. The results suggest that conversions of lignites to preasphaltenes and gases are slower than the conversion of preasphaltenes and asphaltenes to oils. Published by Elsevier Science B.V.