Plasma-metal oxides coupling for CH4-CO2 transformation into syngas and/or hydrocarbons, oxygenates

[Display omitted] •The lower the oxide permittivity the higher the CO2 and CH4 conversions.•Methanol selectivities are favored for the low permittivity oxides.•The temperature increase favors CH4 conversion on MgO.•Re-hydroxylation of MgO occurs at low temperature. Dry reforming of methane was investigated by non-thermal plasma coupled with different metal oxides: BaO, La2O3, ZnO, CaO, α-Al2O3, MgO, γ-Al2O3, TiO2 and CeO2. The deposited power was fixed at 8 W and the total gas flow at 40 mL.min−1 (75 % helium as diluent). Electrical characterization showed that the CO2 and CH4 conversions were enhanced (from 5.6 to 30.6 % for CH4 and from 1.9 to 16.1 % for CO2) when the permittivity was reduced from 2903 to 4.1, respectively. Methanol selectivities were favored for the oxides presenting low permittivities, indicating that reaction is favored under a low electric field, thus low density of reactive species. The effect of reaction temperature was evaluated on MgO catalyst. The increase of the temperature favored CH4 conversion, while reducing methanol selectivity. The oxide characterization by TGA revealed the re-hydroxylation of MgO at low temperature, which was correlated to the improved oxygenated compounds selectivities.