Plasma catalysis in hydrocarbon processing by using non-equilibrium plasma discharges.

摘要

The potential for efficient treatment of hydrocarbons for fuel conversion via plasma catalysis using non-equilibrium (or non-thermal) plasmas has been investigated. For this purpose, methane conversion to hydrogen and synthesis gas (or syngas; mixture of hydrogen and CO) is chosen to be the model process; three reactions of methane were considered: CO₂ reforming, partial oxidation and thermal decomposition.; Two different plasma discharges have been used: Gliding arc discharge and pulsed corona discharge. Experiments with gliding arc discharge have shown that plasma conditions generated by high pressure, continuous and powerful discharge of the gliding arc are very suitable for plasma catalysis applications with both high efficiency and selectivity. On the other hand, plasma generated by the gliding discharge might have thermal or non-thermal properties. Therefore, in order to prove the concept that the conversions are enhanced by the non-equilibrium part of the gliding arc discharge due to plasma catalysis, experiments were performed by using a pulsed corona discharge that provides only non-equilibrium plasma conditions. For the selected processes, non-thermal plasma addition by both pulsed corona discharge and gliding discharges to the preheated mixtures of reactants enhanced the chemical reactions or conversion rates significantly such that increased composition of hydrogen/syngas outputs were obtained. A chemical kinetics modeling of partial oxidation of methane in the presence of plasma has been developed as well.; Additionally, a new diagnostic method to distinguish the equilibrium and non-equilibrium plasma regimes of gliding arc, as well as transition from one to the other, by simultaneously analyzing the electrical and physical properties of the discharge has been developed. A physical model has also been included to determine the existences limits and relative power input to the non-equilibrium stage of the gliding arc discharges.