Thermogravimetric Analysis of Carbon Deposition over Ni/γ-Al₂O₃ Catalysts in Carbon Dioxide Reforming of Methane

Abstract

Carbon formation on Ni/γ-Al 2 O 3 catalysts and its kinetics during methane reforming with carbon dioxide was studied in the temperature range of 500−700 °C using a thermogravimetric analysis technique. The activation energies of methane cracking, carbon gasification in CO 2, as well as carbon deposition in CO 2 −CH 4 reforming were obtained. The results show that the activation energy for carbon gasification is larger than that of carbon formation in methane cracking and that the activation energy of coking in CO 2 −CH 4 reforming is also larger than that of methane decomposition to carbon. The dependencies of coking rate on partial pressures of CH 4 and CO 2 indicate that methane decomposition is the main route for carbon deposition. A mechanism and kinetic model for carbon deposition is proposed.