Bert Verheyde

Conversion of carbon dioxide to value-added chemicals in atmospheric pressure dielectric barrier discharges

The aim of this work consists of the evaluation of atmospheric pressure dielectric barrier discharges for the conversion of greenhouse gases into useful compounds. Therefore, pure CO2 feed flows are administered to the discharge zone at varying discharge frequency, power input, gas temperature and feed flow rates, aiming at the formation of CO and O2. The discharge obtained in CO2 is characterized as a filamentary mode with a microdischarge zone in each half cycle of the applied voltage. It is shown that the most important parameter affecting the CO2-conversion levels is the gas flow rate. At low flow rates, both the conversion and the CO-yield are significantly higher. In addition, also an increase in the gas temperature and the power input give rise to higher conversion levels, although the effect on the CO-yield is limited. The optimum discharge frequency depends on the power input level and it cannot be unambiguously stated that higher frequencies give rise to increased conversion levels. A maximum CO2 conversion of 30% is achieved at a flow rate of 0.05Lmin −1 , a power density of 14.75Wcm −3 and a frequency of 60kHz. The most energy efficient conversions are achieved at a flow rate of 0.2Lmin −1 , a power density of 11Wcm −3 and a discharge frequency of 30kHz. (Some figures in this article are in colour only in the electronic version)

Effect of packing solid material on characteristics of helium dielectric barrier discharge at atmospheric pressure

The influence of a solid material (e.g., Al2O3) on the physical characteristics of helium dielectric barrier discharge (DBD) has been investigated in a cylindrical plasma reactor. The helium DBD with the solid packing shows a multiple current-peak effect, which can be ascribed to the enhancement of charge density due to charge deposition on the Al2O3 pellet surface. The combination of plasma and the solid increases both the peak-to-peak voltage and breakdown voltage of the discharge at a fixed input power but decreases the discharge temperature. It is also found that the presence of the solid has a weak effect on the electron temperature and density in the discharge.

Dielectric barrier discharges used for the conversion of greenhouse gases: modeling the plasma chemistry by fluid simulations

The conversion of methane to value-added chemicals and fuels is considered to be one of the challenges of the 21st century. In this paper we study, by means of fluid modeling, the conversion of methane to higher hydrocarbons or oxygenates by partial oxidation with CO2 or O2 in a dielectric barrier discharge. Sixty-nine different plasma species (electrons, ions, molecules, radicals) are included in the model, as well as a comprehensive set of chemical reactions. The calculation results presented in this paper include the conversion of the reactants and the yields of the reaction products as a function of residence time in the reactor, for different gas mixing ratios. Syngas (i.e. H2 + CO) and higher hydrocarbons (C2Hx) are typically found to be important reaction products. (Some figures in this article are in colour only in the electronic version)