Reforming Of CH₄-CO₂-H₂O For Syngas In A Gliding Arc Plasma Catalytic Reactor

Plasma is generated by applying power to gas,and the chain reaction in plasma is triggered by the collision of gas molecules and electrons to generate free radicals.Reforming in plasma for syngas has been widely concerned in recent years.Syngas?H₂+CO?is an important resource for liquid fuels and chemicals.H₂/CO ratio is the key factor for syngas utilization.Syngas with H₂/CO=2 is typical for methanol synthesis.Bi-reforming of CH₄ can directly produce the ideal syngas,and it therefore is considered as a promising reaction pathway.In conventional catalytic method,H₂O conversion is more kinetically favor than CO₂,thus the real bi-reforming at CH₄/CO₂/H₂O=3/1/2 can't be achieved.In plasma,particularly warm plasma generated by gliding arc,CO₂ can be efficiently activated by vibrational excitation.Hence,it can overcome the challenge occurring in conventional method.In this paper,the plasma parameters of the gliding arc plasma are diagnosed firstly,and then bi-reforming of CH₄ in single plasma and plasma catalytic reactor are researched.The main results are as follows:?1?Plasma parameters of the gliding arc plasma in CH₄-CO₂-H₂O:In the case of CH₄/CO₂/H₂O=3/1/2,specific energy input?SEI?of 110 kJ/mol and flow rate of 2.2 SLM,the obtained discharge voltage,current and rotational period of arc are 3.5 kV,73 mA and1.58 ms.Electron density and OH rotational temperature are 1.5×10¹⁴ cm^-3and 3808 K.With increasing SEI and H₂O/?H₂O+CO₂?,OH rotational temperature and current peaks increase,voltage peaks decrease,electron densities remain in a range of 1×10¹⁴ cm^-31.4×10¹⁴ cm^-3.?2?Reforming of CH₄-CO₂-H₂O in plasma catalytic reactor:for plasma only,reactants conversions gradually increased with the increasing total flow rate and the specific energy input?SEI?,but selectivities of CO and H₂ are weakly depend on SEI and flow rate.In the case of flow rate of 2.2 SLM,SEI of 110 kJ/mol and CH₄/CO₂/H₂O=3/x/?6-x?,?x=0-6?,CH₄conversion is insensitive with H₂O/?H₂O+CO₂?,H₂O conversion increased Drastically,CO₂conversion increase slowly.In plasma catalytic reactor,selectivities of CO and H₂ are close to100%.In all the tested gas hourly space velocity,conversions of CH₄,CO₂ and H₂O reach to a similar value,thus the real bi-reforming can be achieved to produce syngas with H₂/CO=2.