Comparison of rate constants for some molecular tracers generated during artificial maturation of kerogens: influence of kerogen type

The purpose of this work is to carry out artificial maturation of various kerogens under isothermal conditions in open and closed systems and to derive kinetic parameters for specific molecular tracers such as n-C12 and n-C24 alkanes. Results show that individual normal alkane generation from Type I and Type II kerogens follows first-order kinetics in both open and closed pyrolysis systems. However, the normal alkanes generated from Type III samples do not follow a first-order mechanism. For Type I and Type II kerogens, slightly different rate constants are obtained for n-C12 and n-C24 generation whereas for the two Type III kerogens, n-C24 is produced much faster than n-C12. Combining the rate constants derived from open and closed system pyrolysis, Arrhenius plots were obtained for the four samples under study from which accurate sets of kinetic parameters were calculated.