Determination of the rate constants for the substitution of hydrogen atoms by higher normal paraffin hydrocarbons

Using a previously developed labelled atom method, the rate constant was determined for the reaction of hydrogen atoms with n-hexane at pyrolysis temperatures. The thermal decomposition of n-hexane was carried out in a xenon stream at 700-8000C with total reaction pressure 13.3 kPa and partial n-hexane pressure 1.3 kPa (mixture I) and 6.7 kPa (mixture II). The runs were performed in a laboratory vacuum flow system with ground quartz fluidized bed. Propylene-14C was used as the labelled marker with the label at the double bond (H2C = 14C-CH3) and 2.8 x 104 counts/cm3 . min specific radioactivity. The concentration of radioactive propylene in the initial mixture was 1-2 vol. %