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Influence of atmospheric pressure plasma pulse peak voltage electrode spacing

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12 Nov,2020

Influence of atmospheric pressure plasma pulse peak voltage electrode spacing:

 

Influence of atmospheric pressure low temperature plasma pulse peak voltage:

 

When the pulse peak voltage varies from 12 to 16 kV, the methane conversion rate increases obviously with the constant increase of the pulse peak voltage. This is because the peak voltage reflects the energy injected into the reactor, which is equivalent to increasing the energy and number of high-energy electrons in the low-temperature plasma at atmospheric pressure, which is conducive to the improvement of methane activation and conversion rate. However, with the increase of peak voltage, the selectivity of C2 decreases and the yield of C2 does not change significantly. This is also because the increase of peak voltage leads to the increase of high-energy electrons, which leads to the continuous fracture of c-H bond of methane and the formation of carbon deposition, and the continuous decrease of C2 hydrocarbon selectivity.

 

Influence of low temperature plasma discharge electrode spacing at atmospheric pressure:

 

From the variation trend of methane conversion rate, C2 hydrocarbon selectivity and C2 hydrocarbon yield with discharge electrode spacing, it can be seen that the discharge electrode spacing increases, CH2 conversion rate decreases, C2 hydrocarbon selectivity increases, and C2 hydrocarbon yield slightly peaks. At the discharge spacing of 8mm, the yield of C2 was 19.8%. On the one hand, with the increase of electrode spacing, the discharge space increases, and the residence time of methane in the discharge space is prolonged. On the other hand, with the increase of discharge space, under the premise of constant input energy, the electric field intensity between electrodes decreases, and the average energy of high-energy electrons becomes weaker, that is, the energy transferred to a single methane molecule becomes weaker. Therefore, the increase of discharge distance reduces the average energy of high-energy electrons and increases the effective area of plasma. The two have different effects, but the reduction of the average energy of high-energy electrons has a more obvious effect on methane conversion, which shows a trend of decreasing methane conversion rate. The decrease of high-energy electron energy in plasma at atmospheric pressure is not conducive to the further fracture of C-H, which reduces carbon deposition and improves the selectivity of C2 hydrocarbon. The combined effect of the increase of discharge space and the decrease of the average energy of high-energy electrons was that the CH4 conversion rate decreased, the C2 hydrocarbon selectivity increased, and the C2 hydrocarbon yield did not change much.

Influence of atmospheric pressure plasma pulse peak voltage electrode spacing

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