Inhibition of the hydrogen + oxygen reaction by ethylene. Part 1.—Kinetic results

Abstract

The inhibiting action of C₂H₄ on the first and second limits of the H₂+O₂ reaction has been studied over a wide range of mixture composition and vessel diameter in KCl-coated vessels. The results are similar to those observed with C₂H₆, C₃H₈ and C₄H₁₀, except that the inhibition efficiency of C₂H₄ decreases with pressure. The efficiency of C₂H₄ is linearly dependent on O₂ mole fraction, and virtually independent of H₂ mole fraction and vessel diameter. Analysis of reaction products indicates that the C₂H₄ inhibits directly and not through an oxidation product, as found with CH₄ and neopentane. The main primary inhibition reaction at the second limit is the addition of H atoms to C₂H₄ to form C₂H₅ radicals, addition reactions with O and OH radicals being apparently of little importance. The decreasing efficiency of C₂H₄ as the pressure is lowered is attributed to a variation of Q, the fraction of C₂H₅ radicals destroyed without propagating the chain.