The effect of electrode materials on the co-generation of syngas and higher hydrocarbons from CO2 and CH4 using dielectric-barrier discharge has been investigated. The electrode materials tested here include aluminum, copper, steel, and titanium. For the feed of methane in the absence of CO2, the order of activity of methane conversion from high to low was Ti≈ Al > Fe > Cu, while the order of the activity of CO2 conversion was Al > Cu > Ti > Fe for the case of CO2 feed without methane. Regarding the co-feed of methane and CO2, the titanium electrode shows the best activity for the conversions, while the other three materials show a similar performance for the conversions. The effect of dilution gas, helium, on the conversions has also been discussed.

Previous investigations have found that the plasma catalytic conversion of methane is a low-emperature process for the activation of methane, the major component of natural gas. In this paper, the production of acetylene via plasma catalytic conversion of methane over NaY zeolite is discussed. Hydrogen is produced as a by-product during this plasma catalytic methane conversion. A methane/hydrogen feed with oxygen as an additive and helium as a diluent has been studied in this investigation. The CH4/H2/O2 system is found to be more selective for the production of C2 hydrocarbons, compared to the CH4/O2, CH4/H2O, and CH4/CO2 systems reported previously. A higher hydrogen concentration feed is more favorable for acetylene formation. The selectivity and yield of C2 hydrocarbons are related to the hydrogen feed rate, gas temperature, concentration of oxygen additive, and flowrate. The highest yield of C2 hydrocarbons (32%) is obtained at the lowest flowrate used (10 cm3/s; residence time

A novel plasma reduction and calcination (PR&C) method has been recently developed. Upon the experimental investigations on methane conversions, including partial oxidation, methane combustion, NO reduction by methane and CO2 reforming, the catalysts prepared by this PR&C method exhibit a remarkable enhancement in the dispersion, low-temperature activity and stability. A plasma-enhanced acidity has also been addressed, which would play an important role in the improved dispersion. The PR&C method is leading to a better preparation of supported catalysts, esp., those for methane conversion.

In this work, a direct conversion of methane in the presence of carbon dioxide using dielectricbarrier discharge plasmas has been conducted. The product includes syngas (H2 and CO), gaseous hydrocarbons (C2 to C5), liquid hydrocarbons (C5 to C11+), and oxygenates. The liquid hydrocarbons are highly branched, representing a high octane number, while the oxygenates mainly consist of series of alcohols and acids. A detailed analysis of product distribution has been performed under variable feed conditions with different reactor configurations. At the high CH4/CO2 feed ratio, the wider discharge gap (1.8mm) is more favored for the formation of methanol and ethanol. For the production of acetic acid, the narrower discharge gap (1.1mm) is better, especially, with the existence of after-glow zones. Conditions favored for the production of acetic acid are also good for the production of liquid fuels.

This paper discusses catalyst preparation using thermal and cold plasmas. In general, there are three main trends in preparing catalysts using plasma technologies: (1) plasma chemical synthesis of ultrafine particle catalysts; (2) plasma assisted deposition of catalytically active compounds on various carriers, especially plasma spraying for the preparation of supported catalysts; (3) plasma enhanced preparation or plasma modification of catalysts. Compared to conventional catalyst preparation, there are several advantages of using plasmas, including: (1) a highly distributed active species; (2) reduced energy requirements; (3) enhanced catalyst activation, selectivity, and lifetime; (4) shortened preparation time. These advantages are leading to many potential applications of plasma prepared catalysts.