Helen J. Gallon

Dry reforming of methane over a Ni/Al2O3 catalyst in a coaxial dielectric barrier discharge reactor

A coaxial double dielectric barrier discharge (DBD) reactor is developed for plasma-catalytic conversion of CH4 and CO2 into syngas and other valuable products. A supported metal catalyst (Ni/Al2O3) reduced in a methane discharge is fully packed into the discharge region. The influence of the Ni/Al2O3 catalyst packed into the gas gap on the electrical characteristics of the discharge is investigated. The introduction of the catalyst pellets leads to a transition in discharge behaviour from a typical filamentary microdischarge to a combination of spatially limited microdischarges and a predominant surface discharge on the catalyst surface. It is also found that the breakdown voltage of the CH4/CO2 discharge significantly decreases when the reduced catalyst is fully packed in the discharge area. Conductive Ni active sites dispersed on the catalyst surface contribute to the expansion of the discharge and enhancement of charge transfer. In addition, plasma-catalytic dry reforming of CH4 is carried out with the reduced Ni/Al2O3 catalyst using a mixing ratio of CH4/CO2 = 1 and a total flow rate of 50 ml min−1. An increase in H2 selectivity is observed compared with dry CH4 reforming with no catalyst, while the H2/CO molar ratio significantly increases from 0.84 to 2.53 when the catalyst is present.

Electrical and spectroscopic diagnostics of a single-stage plasma-catalysis system: effect of packing with TiO2

The influence of adding TiO2 on the electrical and spectroscopic characteristics of a N2 dielectric barrier discharge (DBD) has been investigated in a single-stage plasma-catalysis system. The introduction of the catalyst into the electrode gap leads to a transition in the discharge behaviour. The presence of the TiO2 pellets in the discharge significantly increases the vibrational temperature of N2 in the DBD, which suggests that the interaction of plasma and catalyst has a strong effect on the electron energy distribution function in the discharge with an increase in electron density in the high-energy tail of the distribution function.

Dynamic Behavior of an Atmospheric Argon Gliding Arc Plasma

The dynamic behavior of an argon gliding arc discharge has been investigated by means of electrical diagnostics and high-speed photography. Two different arc breakdown regimes are identified: initial breakdown in the narrowest electrode gap and restrike breakdown on the electrode surface. It is also found that the anode and cathode arc roots exhibit different motion behaviors.

Transition Behavior of Packed-Bed Dielectric Barrier Discharge in Argon

In this paper, we present the transition behavior of the argon discharge generated in a BaTiO3 packed-bed dielectric-barrier-discharge reactor. A combination of surface discharge and microdischarge can be found in the packed-bed plasma reactor. With the increase of discharge power, microdischarge starts to expand and spread into the surface discharge covering a much larger area on the pellet surface, which also contributes to the interaction between the discharges on the adjacent pellet surface.

Microscope–ICCD Imaging of an Atmospheric Pressure

Images of plasma generation during dry reforming of methane with carbon dioxide in a dielectric barrier discharge reactor using a microscope-intensified charge-coupled device camera have been taken. Comparisons have been made between plasma generations in the absence of a packing material and with different packing materials, including quartz wool, alumina, and barium titanate inside the discharge gap. It has been found that quartz wool can enhance the intensity of plasma generation, leading to improved reaction performance.