Kinetic modeling and reaction pathways for thermo-catalytic conversion of carbon dioxide and methane to hydrogen-rich syngas over alpha-alumina supported cobalt catalyst

Abstract

This study investigates the kinetic modeling and reaction pathway for the thermo-catalytic conversion of methane (CH4) and Carbon dioxide (CO2) over alpha-alumina supported cobalt catalyst. Rate data was obtained from the thermo-catalytic reaction at a temperature range of 923–1023 K and varying CH4 and CO2 partial pressure (5–50 kPa). The rate data was significantly influenced by the changes in the reaction temperature as well as the CH4 and CO2 partial pressure. To estimate the kinetic parameters, the rate data were fitted with five Langmuir-Hinshelwood kinetic models. The discrimination of the kinetic models using different parameters revealed that the Langmuir-Hinshelwood kinetic model with the assumption of CH4 being associatively adsorbed on a single and CO2 being dissociative adsorbed with bimolecular surface reaction best described the rate data. The analysis of the kinetic model using a non-linear regression solver results in activation energies of 15.88 kJ/mol, 36.78 kJ/mol, 65.51 kJ/mol, and 41.08 kJ/mol for CH4 consumption, CO2 consumption, H2 production, and CO production, respectively. The thermo-catalytic reaction was influenced by carbon as indicated by the rate of carbon deposition which was mainly caused by methane cracking. The reaction pathway for the thermo-catalytic conversion of the CH4 and CO2 over the alpha-alumina supported cobalt catalyst can best be described as by CH4 associative adsorption on the alpha-alumina supported cobalt catalyst single site and CO2 dissociative adsorption with bimolecular surface reaction.