Kinetic Studies of Carbon Dioxide Reforming of Methane over Ni−Co/Al−Mg−O Bimetallic Catalyst

The kinetics of CO 2 reforming with CH 4 over a Ni−Co/Al−Mg−O bimetallic catalyst was investigated in a fixed bed reactor at a temperature range of 650−750 °C and the partial pressures of CO 2 and CH 4 ranging from 30 to 190 kPa. Owing to the simultaneous occurrence of the CO 2 reforming reaction and the reverse water−gas shift reaction (RWGS) in the system, the apparent activation energies with respect to reactant consumption and product formation were found different and they are 69.4 and 25.9 kJ/mol for CH 4 and CO 2 consumption and 85.1 and 61.8 kJ/mol for H 2 and CO formation, respectively. It was also found that the reforming rate in terms of CH 4 consumption was less sensitive to CO 2 partial pressures but had stronger dependence on CH 4 partial pressures. At a constant CH 4 partial pressure, the increase in CO 2 partial pressure did not cause significant change in the reforming rate, whereas at a constant CO 2 partial pressure the reforming rate increased with the increase in CH 4 partial pressure. The increase in extra CO 2 at a constant CH 4 pressure led to decreases in hydrogen (H 2 ) formation but increase in carbon monoxide (CO) formation due to the simultaneous occurrence of the reverse water-gas shift reaction. A Langmuir−Hinshelwood (L–H) model was also developed assuming that the dissociation of CH 4 and the reaction between the carbon species and the activated carbon dioxide are the rate determining steps over the Ni–Co/Al–Mg–O. It satisfactorily fits the experimental data as well.