Untitled

We have studied the production of synthesis gas and other hydrocarbons in a dielectric barrier discharge using mixtures of helium, methane and carbon dioxide. It was found that helium has a significant influence on the discharge, decreasing the breakdown voltage and increasing the rate of conversion of CH 4 and CO 2 . However it also decreases the selectivities and the range of stable operating conditions for the discharge. The main products obtained were H 2 , CO, C 2 H 6 and C 3 H 8 but traces of other hydrocarbon, carbon deposition and the formation of condensable products were also detected. The rate of conversion and conversion abilities were obtained by fitting the conversion results to a model.

Section: Productsmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Influence of Helium on the Conversion of Methane and Carbon dioxide in a Dielectric Barrier Discharge

Pinhão

Janeco

Branco

2011

“…In numerous studies the influence of gas composition was investigated showing that products selectivities depend strongly on the ratio CH 4 /CO 2 used [5][6][7]. Carbon dioxide and methane are often introduced into the plasma reactor with a dilution gas known as chemically inactive, like helium or argon [8,9].…”

Section: Introductionmentioning

confidence: 99%

Carbon Dioxide Reforming of Methane Using a Dielectric Barrier Discharge Reactor: Effect of Helium Dilution and Kinetic Model

Goujard

Tatibouët

Batiot‐Dupeyrat

2011

The carbon dioxide reforming of methane to synthesis gas was investigated in a dielectric barrier discharge reactor at room temperature. The influence of dilution of reactants by helium was studied. We showed that, at a fixed contact time, the conversions of CH 4 and CO 2 increase when the amount of helium in the gas mixture increases. This result is attributed to the ''penning ionization'' phenomenon, which corresponds to an energy transfer from excited He to molecules in ground state (CH 4 , CO 2 ). The selectivity to products is affected by the dilution factor. As soon as helium is present in a large amount the formation of products resulting from recombination of methyl radicals (such as C 2 , C 3 and C 4 ) is less favourable due to the lowest probability of collisions to proceed. A kinetic model is proposed based on the assumption that the reactant molecules CH 4 or CO 2 are attacked by active species produced by the plasma discharges, and the production of this active species are function of the plasma power. This model which takes into account the dilution by helium fits particularly well the experimental data we obtained.

“…As an alternative, the cold plasma generated by different discharge types provides a new way for the chemical process, such as chemical synthesis, treatment of hazardous waste and surface modification [12]. For the process of dry reforming of CH 4 , different discharge types to generate the cold plasma were investigated, such as gliding arc gas discharge [13][14][15], pulsed glow discharge [16], radio-frequency discharge [17,18], pulsed microwave discharge [19], two pins discharge [20], pulsed corona discharge [21], AC discharge [22], and especially the dielectric barrier discharge (DBD) [23][24][25][26][27], etc. The DBD is the most commonly used type to produce the cold plasma with energetic electrons at atmosphere pressure [28].…”

Section: Introductionmentioning

confidence: 99%

Investigation of Dry Reforming of Methane in a Dielectric Barrier Discharge Reactor

Wang

Yan

et al. 2009

144

Low temperature conversion of CH 4 and CO 2 was investigated in a coaxial dielectric barrier discharge reactor at ambient pressure. Main parameters, including the input power, the residence time, the discharge gap, the molar ratio of the feed gases and the multi-stage ionization design were evaluated to understand the ways to improve the conversion of greenhouse gases and reduce the output of by-products. At certain input power, the conversion of CH 4 and CO 2 can reach 0.797 and 0.527, respectively, when the molar ratio of CH 4 /CO 2 is one. When this ratio was low to 1:5, the conversion of CH 4 was promoted to 0.843 and the selectivity to CO and H 2 was almost 100%. The multi-stage ionization favored the conversion of CO 2 , which would also be an efficient design to promote the selectivity to the main products such as CO and H 2 and suppress the selectivity to the by-products.