Microkinetic Modeling of the CO₂ Desorption from Supported Multifaceted Ni Catalysts

Abstract

The conversion of CO2 into valuable products with hydrogenation reactions on Ni catalysts requires a fundamental understanding of the interaction of CO2 with the Ni surface. Microkinetic modeling is used to investigate the interaction of CO2 with a multifaceted Ni crystal and compared to temperature-programmed desorption (TPD) experiments from supported Ni catalysts. TPD experiments were performed for Ni/γ-Al2O3 and Ni/SiO2 catalysts. Uncertainties in the DFT-derived model parameters were accounted for by a global uncertainty analysis (GUA). On the basis of the model, the adsorption and desorption of CO2 exhibit a structure–sensitivity for the investigated Ni facets. Whereas the initial multifaceted TPD model is not in quantitative agreement with the experimentally recorded desorption profile, the GUA reveals a feasible set of model parameters that are in close agreement with the data. The comparison of the desorption profiles of the different catalysts and the multifacet simulation shows that desorption of CO2 from basic sites and desorption from the Ni facets overlap and thus have similar desorption kinetics.