Conversion of methane by an electric barrier-discharge plasma using an inner electrode with discharge disks set at 5 mm intervals

• The between discharge disks with 5 mm interval can increase methane conversion.
• The interval can improve the selectivity of propane, C4 and over hydrocarbon.
• The product carbon selectivity is not changed with increasing flow rate at Pw of 32 W.
• The product carbon selectivity of both reactors is different at Pw of 3 W.

In this study, we investigated the effect of inner electrode structure on methane conversion (XCH4XCH4) and product selectivity using dielectric barrier-discharge plasma. We used two types of inner electrodes: those with discharge disks set at 5 mm intervals (Type A) and those with discharge disks set at 0 mm intervals (Type B).When electric power (Pw) was increased, the methane conversion (XCH4XCH4) of Type A and Type B increased. However, the XCH4XCH4 of Type A reactor was lower than that of Type B reactor, irrespective of Pw. When the total thickness of the discharge disks set at 0 mm intervals was the same as that in Type A, XCH4XCH4 was lower than the XCH4XCH4 for Type A or Type B. This result shows that the presence of discharge disk intervals can result in increased XCH4XCH4. The primary product was ethane when using electrodes with/without intervals under various conditions. When Pw was increased in Type A, the product carbon selectivity (PCS) of propane and C4+ hydrocarbon increased with increased Pw and the PCS of ethylene decreased. When Type B was used, the PCS of acetylene also increased with an increase in Pw. These results show that Type A reactors can promote homologation and Type B reactors can promote dehydration. When the flow rate (F0) was varied at a Pw of 3 or 32 W, XCH4XCH4 decreased with increased F0. Ethane was again the primary product, and the F0 value did not dramatically affect the PCS.