TEMPERATURE AND PRESSURE-DEPENDENCE OF N-HEXADECANE CRACKING

The rates and product compositions of hexadecane cracking are reported for temperatures ranging from 300 to 370 degrees C and pressures of 1 50 to 600 bar. The overall apparent activation energy at an intermedia te pressure of 300-350 bar is about 74 kcal/mol. This is higher than t he overall 60 kcal/mol energy consistent with higher temperature measu rements, even though the rates from our highest temperatures overlap w ith those from earlier reports. The product composition is consistent with a free radical mechanism in which alkene intermediates react with primary and secondary radicals to form branched and normal liquid pro ducts both smaller and larger than the starting material. Pressure has a retarding effect on the rate of reaction, but the dependence is not measured precisely enough to say more than that the survival of oil i s likely to vary by a factor of two or so under typical geologic condi tions. A simple kinetic model having five first-order reactions is pre sented that predicts the lumped kinetic species of C-1, C-2-C-4, C-5-C -9, C-10-C-15, C-16, and C-16+. The gas is depleted in methane compare d to most natural gas.