Cold plasma dielectric barrier discharge reactor for dry reforming of methane over Ni/ɤ-Al₂O₃-MgO nanocomposite

Dry reforming of methane (DRM) to syngas in a dielectric barrier discharge (DBD) plasma reactor over Ni-loaded ɤ-Al₂O₃-MgO nanocomposite catalysts has been investigated. The catalysts are prepared by modified incipient wetness impregnation method, assisted by cold plasma treatment. The samples are characterized by XRD, N₂ adsorption-desorption, H₂-TPR, CO₂-TPD, FESEM and EDX. The performance of the catalyst for DRM is evaluated at various specific input energy (SIE J ml⁻¹) and gas hourly space velocity (GHSV, h⁻¹). The maximum conversion achieved are 74.5% and 73% for CH₄ and CO₂ respectively, over 10% Ni/ɤ-Al₂O₃-MgO at specific input energy (SIE) = 300 J ml⁻¹ and gas hourly space velocity (GHSV) = 364 h⁻¹. The main reaction products are H₂ (29.5%), CO (30.5%) with H₂/CO = 1 inferring RWGS reaction is suppressed for 12 h operation time. The enhanced conversion and yield are due to the strong metal-support interaction, high Lewis basicity and stable 10% Ni/ɤ-Al₂O₃-MgO catalyst as well as the plasma-catalyst interface. The energy efficiency (EE) of the plasma-catalytic DRM is higher (0.117 mmol kJ⁻¹) compared to plasma only (0.087 mmol kJ⁻¹) demonstrating the synergy between catalyst and plasma. The reaction mechanism is also proposed to postulate the steps involved in the DRM.