KINETIC RATE MODELS FOR DISSOLUTION OF TURKISH LIGNITES IN TETRALIN UNDER NITROGEN OR HYDROGEN ATMOSPHERES

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 teste d to estimate the rates of formation of these products. The proposed m echanisms are based on the assumptions that the reactions are irrevers ible, pseudo-first order with respect to the reacting species, and the ir rate constants obey linear Arrhenius behavior. The product distribu tions data have been assessed by a simple simulation program, The resu lts indicated that certain simple kinetic models represent the data we ll and the prevailing mechanism changes slightly with temperature. The estimated energy of activation for dissolution changes from 54 kJ/gmo l to 185 kJ/gmol depending on the lignite and the suggested reaction m odel. The results suggest that conversions of lignites to preasphalten es and gases are slower than the conversion of preasphaltenes and asph altenes to oils. Published by Elsevier Science B.V.