Thermal evolution of n- and iso-alkanes in oils. Part 1: Pyrolysis model for a mixture of 78 alkanes (C1–C32) including 13,206 free radical reactions

A mechanistic model consisting of 13,206 lumped free radical reactions has been developed to describe the thermal evolution of a mixture of 78 alkanes: all n-alkanes from C1 to C32 and 46 branched alkane model compounds from C4 to C32. The mixture was meant to represent the major part of the saturated fraction of petroleum. The rate constants used are available from the literature. The lumping together procedure is described and the model validated on the basis of several experimental results from the literature and relating to pure alkanes. The model is also compared to the saturated fraction obtained from pyrolysis of Elgin oil at 372 °C for up to 1000 h. The cracking global activation energy of n-C15 as well as iso-C15 is close to 69 kcal/mol in the range 200–350 °C. The implications of the model for geological reservoirs will be discussed in a following paper.