Bogdan Ulejczyk

Decomposition of chloromethanes in gliding discharges

Gliding discharge plasma was used for decomposition of tetrachloromethane and trichloromethane. Air containing 8000 ppm or 20 ppm of water vapor was the carrier gas. The course and yield of the process were studied as a function of initial concentration of tetrachloromethane and trichloromethane, gas flow rate, and water vapor content. The conversion was high in all cases—it reached 90% for tetrachloromethane and 100% for trichloromethane. The conversion rate of the chloromethane compounds increased with increasing initial concentration of these compounds in the reaction mixture. Changing the water vapor content in the reaction mixture from 20 ppm to 8000 ppm increased the conversion rate of chloromethanes.

Carbon Tetrachloride Decomposition by Pulsed Spark Discharges in Oxidative and Nonoxidative Conditions

The estimation of pulsed-spark-discharge efficiency for destroying unwanted stable gaseous impurities is an object of the present study. A laboratory-scale reactor was developed to study the efficiency of pulsed spark discharges (PSDs) for CCl₄ decomposition under oxidative and nonoxidative conditions at atmospheric pressure. In the discharge, chlorine gas was the main product produced from CCl₄ in addition to minor amounts of additional products. These products were the following: 1) C₂Cl₄, C₂Cl₆, and solid deposits containing chlorine and carbon for the inlet CCl₄ + Ar mixture and 2) CO₂ with small amounts of COCl₂ for CCl₄ + O₂ mixture. For both diluting gases, it was possible to reach a high CCl₄ conversion (98% for CCl₄ + O₂ and 93% for CCl₄ + Ar). CCl₄ was chosen as a model substance, because of its simple chemical composition and high stability of its structure. For this reason, the positive result of experiments with CCl₄ gave evidence that using the PSD may be an effective way for the abatement of gaseous pollutant emission.

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

Experimental Investigation of the Dynamics and Space Range of the Gliding Arc in Three-Electrode System

The gliding discharge visualization in mixed streams of argon and oxygen was recorded with the use of a high-speed camera in order to test a plasma reactor new gas supply system, which consisted of two nozzles of a special shape. The plasma reactor was equipped with three electrodes powered by a three-phase alternating current. The estimated maximal discharge diameter was 32 mm. The diameter of the gas stream, where the stoichiometric composition of reactants was reached, amounted to 8 mm, and it was smaller than the maximal discharge diameter. In these conditions, it may be expected that the efficiency of the chemical reaction should be the highest for given experimental conditions.

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%.

Plasma reactors with variable gas linear velocity. Studies on ozone synthesis

The original concept of the gas flow through the reactor was presented. Two kinds of discharge elements were compared. In the simple surface discharge arrangement, in which the metal mesh adjacent to the ceramic dielectric was used, similar effects as in more complicated systems were obtained. In one-side cooling reaction space the high ozone concentrations and high energy efficiencies of the process, even at 25oC, were obtained.

Decomposition of halocarbons in the pulsed dielectric barrier discharge

A dielectric barrier discharge powered by pulsed power supply system was used for the decomposition of tetrachloromethane, trichloromethane and trichloroethylene. The study was performed in atmospheric air with concentration of water vapor 0.4%. The effect of specific energy on overall halocarbons conversion and selectivity of halocarbons conversion to carbon dioxide, carbon monooxide, chlorine and hydrogen chloride was studied. In studied system the increase of the specific energy increased the selectivity of halocarbons conversion to carbon dioxide and chlorine. For the specific energy ~7 kJ/mol, the maximum conversions of tetrachloromethane, trichloromethane and trichlorothylene were 66, 60 and 93% respectively.