The Reaction Mechanism and Its Kinetic Model of CO2 Reforming with CH4 over Ni-Mg15@HC Catalyst

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In this paper, the kinetic of CO2 dry reforming with CH4 (DRM) over the Ni-Mg15@HC catalyst was studied after excluding the influence of internal and external mass transfer at 700–850 °C. At the same time, the partial pressures of CH4 and CO2 were varied from 10 to 50 kPa. The experimental results demonstrated that the reaction rate was sharply increased with the increase of CH4 partial pressure, while the increase of CO2 partial pressure led to a relative increase of the reaction rate. Therefore, it could be said that CH4 dissociation was the rate determining step for DRM reaction. Moreover, the apparent activation energy of CH4 consumption (48.6 kJ/mol) during DRM reaction was higher than that of CO2 consumption (30.1 kJ/mol), which also confirmed the above assumption. On the basis of the reaction mechanism, a Langmuir–Hinshelwood kinetic rate model was developed, and the kinetic parameters were also estimated by the nonlinear least square regression method. The developed model could satisfactorily fit the experimental data, and R2 was as high as 0.965. The apparent activation energy of CH4 consumption during DRM reaction was higher than that of CO2, then the rate determining step was determined. A kinetic rate model was developed, which could well describe the experiment.