Kinetic studies of the catalytic oxidation of methane. 2. Methyl radical recombination and ethane formation over 1% strontium/lanthanum sesquioxide

Abstract

The early stages of the catalytic oxidative conversion of methane to ethane over 1% Sr/La{sub 2}O{sub 3} have been studied at 1086 K, using a heatable tubular flow reactor (containing the catalyst) coupled to a photoionization mass spectrometer. Temporally resolved concentrations of CH{sub 3}, C{sub 2}H{sub 6}, and C{sub 2}H{sub 4} were recorded along the catalyst bed. Conditions used resulted in negligible loss of the reactants (Ch{sub 4} and O{sub 2}, 75%. No indication wasmore » found of any heterogeneous deep oxidation of methyl radicals or of any heterogeneous conversion of methane to C{sub 2} compounds (C{sub 2}H{sub 6} or C{sub 2}H{sub 4}). Rate constants for the CH{sub 3} + CH{sub 3} reaction under the conditions of these experiments (which were used in the kinetic modeling of the experimental results) were obtained in separate experiments using the same reactor but with the catalyst removed, experiments in which the CH{sub 3} radicals were produced by laser photolysis of acetone and the decay of CH{sub 3} was monitored in time-resolved experiments.« less