(544ex) CO2 Hydrogenation with Ni/MgO Catalysts
The influence of the nickel load on the performance of Ni/MgO catalysts in terms of rate controlling steps and the reaction kinetics were investigated. The MgO backbone was compared to Ni/MgO catalysts with different Ni load between 11-27%wt.
The MgO backbone without Ni-load is selective to CO formation, admixture of nickel shifts the selectivity to methane with high nickel load leading to higher methane selectivity and higher CO2 conversion. The reaction kinetics of the CO2 methanation can be modelled with a Langmuir-Hinshelwood based approach, as proposed by Koschany et. al. . Different rate models can be applied, depending on what is assumed to be the rate determining step. Temperature dependency was modelled with an Arrhenius approach. The activation energy depends on the Ni-load, suggesting that with increasing Ni-load mass transfer becomes a key step in conversion.
 F. Koschany, D. Schlereth, and O. Hinrichsen, âOn the kinetics of the methanation of carbon dioxide on coprecipitated NiAl(O)x,â Appl. Catal. B Environ., vol. 181, pp. 504â516, 2016.