Reaction Mechanism of the Homogeneous Thermal Decomposition of Acetylene

Article abstract of DOI:10.1021/j100440a002

A modeling study is reported in which experiments on the rate of and product distribution from C2H2 pyrolysis from 625 to 3400 K are described with a single mechanism.The essential primary mechanism at low temperatures proves to consist of an H-atom, vinyl radical chain H + C2H2 -> C2H3, C2H3 + C2H2 -> C4H4+ H producing vinyl acetylene at early times.At high temperatures this is replaced by the ethynyl chain H + C2H2 -> C2H + H2, C2H + C2H2 + H producing diacetylene.By considering a variety of studies simulteneusly it was possible to assign rate constant expressions to the key elementary reactions.While all of the basic observations on the primary decomposition are accounted for by final mechanism, uncertainties still remain in the rates of secondary reactions and in the magnitudes of the fallof corrections required for the unimolecular reactions involved.