Michał Młotek

Plasma-catalytic Conversion of Methane by DBD and Gliding Discharges

Abstract The methane conversion into C2 hydrocarbons was examined at atmospheric-pressure plasmas generated by dielectric barrier discharges (DBD) and gliding discharges (GD) using different mixtures of gases (CH4 with Ar, CO2, and H2). Ethane was the main product of the methane conversion in filamentary DBD, whereas mainly acetylene was generated by gliding discharge. It was found that one of the commercial catalysts (Cu/Zn/Al2O3) can be used for the methane conversion in DBD. A new type of the gliding discharge reactor with a widening upwards working chamber, and two vertical electrodes was designed. A spouted-bed of alumina-ceramic particles (0.16 - 0.5 mm) was maintained in the inter-electrode volume by a stream of gaseous reactants passing upward. The presence of the spouted bed resulted in: 1) an increase in voltage and decrease in current, and 2) an increase of the overall methane conversion and selectivity into C2 hydrocarbons.

Purification of the gas after pyrolysis in coupled plasma-catalytic system

Abstract Gliding discharge and coupled plasma-catalytic system were used for toluene conversion in a gas composition such as the one obtained during pyrolysis of biomass. The chosen catalyst was G-0117, which is an industrial catalyst for methane conversion manufactured by INS Pulawy (Poland). The effects of discharge power, initial concentration of toluene, gas flow rate and the presence of the bed of the G-0117 catalyst on the conversion of C7H8, a model tars compounds were investigated. Conversion of coluene increases with discharge power and the highest one was noted in the coupled plasma-catalytic system. It was higher than that in the homogeneous system of gliding discharge. When applying a reactor with reduced G-0117 and CO (0.15 mol%), CO2 (0.15 mol%), H2 (0.30 mol%), N2 (0.40 mol%), 4000 ppm of toluene and gas flow rate of 1.5 Nm3/h, the conversion of toluene was higher than 99%. In the coupled plasma-catalytic system with G-0117 methanation of carbon oxides was observed.

A comparison of carbon tetrachloride decomposition using spark and barrier discharges

Abstract The decomposition of CCl4 in air was investigated at atmospheric pressure in two discharges. Reactors used to generate electrical discharges were powered by the same electric power supply. In both reactors, nearly 90% conversion of CCl4 was obtained. All chlorine was in the form of Cl2 in the process carried out in the barrier discharge, while in the spark discharge, COCl2 was formed. The conversion of CCl4 to COCl2 ranged from 2 to 12%. NO was formed in both discharges but the NO content in the gas leaving the reactors was 1.7–2.7% for the spark discharge and 0.045–0.06% for the barrier discharge. O3 was produced only in the barrier discharge and its content ranged from 0.1 to 0.2%. Graphical Abstract

Plasma-Catalytic Processes in Gliding Discharges

Abstract Two kinds of plasma-catalytic processes initiated by gliding discharges (GD) were examined: 1) nitrous oxide decomposition and 2) methane non-oxidative coupling to C2 hydrocarbons. In the first case, the GD reactor with stationary catalyst bed was used. It was found that the selected catalysts CuO/Al2O3 and Fe2O3/ Al2O3 may increase the conversion rate of N2O into N2 and O2 in the plasma-catalytic system, not affecting, however, its oxidation to NO. For the methane coupling, a new model of GD reactor has been developed with a mobile (spouted) bed of catalyst particles. In that process, C2 hydrocarbons were the dominant reaction products, however, some amounts of non-volatile substances (e.g. soot) were also produced. When using alumina-ceramic particles, acetylene was the main product with none or traces of other C2 hydrocarbons. In the presence of Pt/Al2O3, however, much more ethylene and ethane were produced.

Hydrogen production from ethanol using dielectric barrier discharge

Hydrogen production from a water-ethanol mixture in dielectric barrier discharge was investigated. The effect of feed stream of ethanol on ethanol conversion and energy yield was studied. In the reactor with 2.6 cm³ of active volume the maximum ethanol conversion was 100% an energy yield of 8.4 g (H<inf>2</inf>)/kWh. Besides H<inf>2</inf>, the reaction products were CO, CH<inf>4</inf> and a small amount of C<inf>2</inf>H<inf>4</inf>, C<inf>2</inf>H<inf>6</inf>, CO<inf>2</inf> and soot.

Steam reforming of ethanol in spark discharge generated between electrodes made from a Ni 3 Al alloy

A spark discharge, which was produced between two electrodes made from a Ni3Al alloy, was applied in the production of hydrogen in the steam reforming of ethanol. The influence of the water:ethanol molar ratio and feed flow on the total conversion rate of ethanol, as well as the conversion of ethanol into hydrogen, energy efficiency and selectivity of ethanol conversion to hydrogen, carbon monoxide, carbon dioxide, methane, ethylene and acetylene were studied. The highest energy efficiency was 38 gH2/kWh. The highest selectivity of ethanol conversion to hydrogen was 89%. The highest conversion of ethanol was 78%.

Conversion of tetrachloromethane in large scale gliding discharge reactor

Abstract Gliding discharge plasma in a large scale reactor was used for decomposition of tetrachloromethane. The new power supply system based on a power inverter was used. The conversion of CCl4 was investigated in air at normal pressure. The reactor was made of a quartz-glass tube 60 mm in diameter and contained three converging electrodes 140 mm long. Effects of the initial CCl4 concentration, gas flow rate and discharge power on CCl4 conversion have been studied. The conversion of CCl4 was high in all cases reaching a maximum of 90%. The conversion of tetrachloromethane decreased with increasing initial concentration of CCl4 in the reaction mixture. Changing the gas flow rate from 1000 Nl h-1 to 1400 Nl h-1 decreased the conversion of tetrachloromethane. Graphical Abstract