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The oxidation behavior of Ni/Al 2 O 3 catalyst in CO 2 plasma was investigated compared with CO 2 thermal oxidation, aiming for providing new insight into oxidationreduction cycle of plasma catalysis of dry methane reforming (DMR). Temperature programmed reaction spectrometry was applied to enable a quantitative analysis of gas consumption which is related to the oxidation and reduction of Ni/Al 2 O 3 catalysts. The nonthermal plasma oxidation mechanism was further analyzed by Raman spectroscopy, showing the crosssectional distribution of NiO over the 3 mm spherical catalyst pellets. Nonthermal plasmaexcited CO 2 oxidizes Ni only near the external surface of spherical pellets with 20 μm depth: both dielectric barrier discharge generation and plasmaexcited species diffusion into the internal pores are inhibited. The partially oxidized Ni catalyst in the external surface would promote plasmaenabled oxidationreduction cycle, which was further correlated with coke formation behavior in plasma catalysis of DMR.

A kinetic study revealed that a Ni/Al2O3 catalyst exhibited a drastic increase in CH4 and CO2 conversion under nonthermal plasma when lanthanum was added to the Ni/Al2O3 catalyst as a...

DMR is an endothermic reaction. To satisfy the reaction enthalpy, high-temperature thermal energy is required to meet the large positive value of Gibbs free energy in thermal reforming for spontaneous reaction [9]. Significantly,