Some features of the gas phase oxidation of n -butenes

Abstract

Conventional kinetic techniques (static and flow systems) have been used in conjunction with an integral gas chromatographic analytical system in a study of the oxidation behaviour of butene-1, cis butene-2 and trans butene-2. The cis and trans isomers of butene-2 behaved indistinguishably. All three olefins gave qualitatively the same products, but butene-1 differed in the proportions of the individual products formed, and also in oxidation rate. A mechanism, based on that previously proposed for the ethylene + oxygen system, has been found to account for these differences. The ethylene mechanism is only possible, however, because of the slow rate of oxidation of the allylic type radicals easily formed in the reactions. The relative stability of these radicals provides a natural explanation of the phenomenon of self-inhibition observed in olefin + oxygen reactions. The discontinuous production of intermediate substances noted during the oxidation of butene-2 at high reaction rates, provides further evidence for a thermal theory of cool-fiame formation. Acetaldehyde has been found to be the degenerate branching agent and the maximum reaction rate of these systems was found to be identically related to the concentration of this substance.