Effects of Olefins on the Thermal Decomposition of Propane Part IV. Influence of Propylene

✍ Scribed by A. Dombi; P. Huhn

• Publisher: John Wiley and Sons
• Year: 1986
• Tongue: English
• Weight: 477 KB
• Volume: 18
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550180304

✦ Synopsis

On the basis of the thermal decomposition of mixtures of propylene and propane with molar ratios of 0.0-0.33 in the temperature range 779-812 K, the influencing functions describing the inhibition by propylene of the decomposition of propane were determined. The rate-reducing effect is explained mainly by the reactions C3H6 + 'R -C3H5 + RH (in which 'R = 'H, 'CH, and 2-C3H7) and also by the addition reactions It was established that the bulk of the ally1 radicals formed participate in the chain step, but, due to their lower reactivity, they restore the decomposition chain more slowly than the original radicals do.

From the characteristic change in the ratio uCH,/uH2, the rate ratios of hydrogenabstraction reaction by radicals from propylene and propane could be determined. In these reactions there was no significant difference between the selectivities of the radicals. For an interpretation of the changes, the decomposition mechanism must be completed with the reaction C3Hs + 2-C&l-C& + C3H6. Evaluation of the influencing curves revealed that the initiation reactions must be taken into account.

By parameter estimation we have determined the rate ratios characterizing the above initiation reactions, the unimolecular decomposition of propane, hydrogen abstraction by radicals from propane and propylene, intermolecular isomerization of the 2-propyl radical via propane and propylene, and abstraction of propane hydrogens by the ethyl and methyl radicals; these are given in Tables 11.