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

摘要

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 H-2 and CO production were 46.1 +/- 2.5, 46.2 +/- 12.4, 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 H-2 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 CH4 and CHxO decomposition are suggested to be the rate-determining steps of the CH4/CO2 reaction over the Ni-K/CeO2-Al2O3 catalyst. (c) 2006 Elsevier B.V. All rights reserved.