A study on methane coupling to acetylene under the microwave plasma

By optimizing the microwave chemistry reactor made of the rectangular waveguide resonator, the methane conversion (the maximum 93.7%), the C(2) hydrocarbon yield (the maximum 91.0%) and the acetylene yield (the maximum 88.6%) were all greatly increased under the microwave plasma. Furthermore, for the optimal reactor, the change of the methane conversion and the C(2) hydrocarbon yield is little within the range of the pressures in the experiments. The C(2) hydrocarbon is mainly made up of acetylene, and the selectivity for acetylene is above 90%. Energy yield and space time yield of acetylene are also high. Optical emission spectroscopy (OES) was adopted for the diagnosis of methane coupling to acetylene under microwave plasma. The excited species (CH, C(2), H(2), H(alpha)) were detected in the spectra range of 300-750 nm. Based on the products and the excited species, the reaction mechanism of methane coupling under microwave plasma was investigated, using the thermodynamics and kinetics of the chemical reaction.