Stationary states of hydrogen-producing reactions in nonequilibrium plasma

In this work, stationary states of hydrogen-producing reactions in nonequilibrium plasmas are explored, namely the water splitting and water gas shift reactions. For both reactions, the effluent from the reactor at long residence times in the plasma was found to be independent of the influent speciation. In other words, feeding the reactor either 0.1H₂O or 0.1H₂ + 0.05O₂ by mole produced the same effluent composition, and similarly, feeding the reactor 0.1CO + 0.1H₂O produced nominally the same effluent as 0.1CO₂ + 0.1H₂. For both reactions, the effluent from the plasma was found to be very far from local equilibrium at the total pressure and background temperature of the plasma and shifted in the endothermic direction relative to the local equilibrium speciation. This work further demonstrates that special attention must be paid to the recombination zone in plasmachemical processes. The recombination zone tends to drive the gas composition from plasma stationary states back towards local equilibrium.