Kinetic study of the catalytic carbon dioxide reforming of methane to synthesis gas over Ni-K/CeO2-Al2O3 catalyst Original Research Article

The effect of reaction parameters on the catalytic activity of Ni-K/CeO2-Al2O3 catalyst for carbon dioxide (CO2) reforming of methane (CH4) was studied. The kinetic behavior of the Ni-K/CeO2-Al2O3 catalyst in the reforming reaction was investigated as functions of temperature and of partial pressures of CH4 and CO2. The apparent activation energy for CH4 and CO2 consumption, and H2 and CO production were 46.1 ± 2.5, 46.2 ± 2.4, 54.0 ± 2.6 and 47.4 ± 1.7 kJ/mol, respectively, for the temperature range of 873–1073 K. It was found that an increase of the H2 partial pressure leads to a continuous enhancement of the rate of CO formation, due to the simultaneous occurrence of the water–gas shift reaction. The rate of methane consumption is strongly affected by the partial pressure of methane. Variation of the CO2 partial pressure has a strong influence on the rate of methane consumption at low partial pressures of 0–0.1 atm, while it is insensitive to CO2 partial pressure at high pressures. A mechanism of the CH4/CO2 reaction has been proposed based on the experimental results and literature review. Based on the mechanism, a kinetic model was developed, which was found to predict satisfactorily the kinetic measurements. CH4 activation to form CHx and CHxO decomposition are suggested to be the rate-determining steps of the CH4/CO2 reaction over the Ni-K/CeO2-Al2O3 catalyst.