K. Ceylan et A. Olcay, KINETIC RATE MODELS FOR DISSOLUTION OF TURKISH LIGNITES IN TETRALIN UNDER NITROGEN OR HYDROGEN ATMOSPHERES, Fuel processing technology, 53(3), 1998, pp. 183-195
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.