catalytic and non-catalytic conversion of methane to c2 hydrocarbons in a low temperature plasma

the direct conversion of methane to c2 hydrocarbons, in a quartz tube reactor enforced by a dc corona discharge, was investigated at atmospheric pressure. the process was carried out in the presence of metal oxide catalysts of mn/w/sio2, mn/w/sio2 (tetraethyl orthosilicate, teos), and mn/w/cnt (supported on carbon nanotubes). the total yield to c2 hydrocarbons in the presence of metal oxide catalysts in plasma environment was in the order of mn/w/sio2> mn/w/sio2 / teos> plasma only> mn/w/cnt. the order changes to mn/w/sio2>mn/w/cnt>plasma only> mn/w/sio2/ teos, when the selectivity and yield of ethylene is considered. the highest yield to c2 hydrocarbons was 15.8%, which was obtained by using mn/w/sio2 in combination with gas discharge plasma without external heating; it was lower when the same feed composition was tested over this catalyst at 825 °c. the catalyst na2wo4/mn2o3/sio2 –b1, which produces the least carbon oxides, gives rise to the highest production of higher hydrocarbons and ethylene. catalysts na2wo4/mn2o3/sio2 /teos-b2 and na2wo4/mn2o3/‍cnt-b3,due to their high selectivity toward carbon oxides, show low efficiency in producing more valuable hydrocarbons.