Thermal Decomposition of 2-Pentene

Abstract

Thermal decomposition of 2-pentene was studied in a flow apparatus under an atmospheric pressure, at temperatures ranging from 480 to 730°C, and with 'residence times from 0.05 to 35 sec and nitrogen/2-pentene mole ratios 6 and 15. The overall reaction obeys the first order rate equation with the rate constant being log k (sec-1)=12.3-53000/4.575 T. The main reaction products were approximately equimolar amounts of methane and butadiene, consisting 50∼60 mol% of 2-pentene decomposed. Other reaction products were hydrogen, ethylene, ethane, propene, 1-butene, 2-butene, 1, 3-pentadiene, 3-methyl-1-butene and 4-methyl-2-pentene.
The reaction can be accounted for by a free-radical chain process with complication due to competition between decomposition and isomerization of alkenyl as well as alkyl radicals. Ex- perimentally observed product distributions as well as reaction rates are found to be in good agreement with those calculated on the basis of estimated kinetic parameters of the elementary reactions in the proposed chain scheme.