Plasma Pyrolysis of Natural Gas (NG)
can be performed in Gliding Arcs (GlidArc), cold and powerful electrical discharges. Two bench scale reactors are used: a glass 0.1-L cold-wall vessel or 1.35-L steel tube. Two or six knife-shaped steel electrodes are put around the gas-flow axis forming a flat or cylindrical nozzle. The gas flow-rate is up to 2.3 m3(n)/h. The NG can be overheated in the larger reactor jacket and then injected between the electrodes at atmospheric pressure. The temperature of the exiting is below 500°C. Up to 34% of the NG has been converted, mostly to H2 and C2H2, at a promising energetic efficiency.
GlidArc discharge in pure methane at 1 atm
Two main pyrolysis reactions are observed:
CH4 = C + 2 H2; DH°(298) = 74.6 kJ/mol CH4,
CH4 = 0.5 C2H2 + 1.5 H2; DH°(298) = 188.2 kJ/mol CH4
at a high selectivity to acetylene (70 to 90%) and only 30 to 10% selectivity to soot. The energetic expense for 1 m3(n) H2 + 0.22 m3(n) C2H2 is about 4 kWh for that bench scale. It certainly can be lowered.
We are exploring an idea of a GlidArc-assisted pyrolysis of the NG that may be used for Zero- or Low-Emission-Vehicle as a part of systems such as Hydrogen fuel cell or Hythane-like (CH4 + H2) fuelled engine, respectively.