Fixed bed adsorption of CO₂/H₂ mixtures on activated carbon: experiments and modeling

We present breakthrough experiments in a fixed bed adsorber packed with commercial activated carbon involving feed mixtures of carbon dioxide and hydrogen of different compositions. The experiments are carried out at four different temperatures (25 °C, 45 °C, 65 °C and 100 °C) and seven different pressures (1 bar, 5 bar, 10 bar, 15 bar, 20 bar, 25 bar and 35 bar). The interpretation of the experimental data is done by describing the adsorption process with a detailed one-dimensional model consisting of mass and heat balances and several constitutive equations, such as an adsorption isotherm and an equation of state. The dynamic model parameters, i.e. mass and heat transfer, are fitted to one single experiment (reference experiment) and the model is then further validated by predicting the remaining experiments. Furthermore, the choice of the isotherm model is discussed. The assessment of the model accuracy is carried out by comparing simulation results and experimental data, and by discussing key features and critical aspects of the model. This study is valuable per se and a necessary step toward the design, development and optimization of a pressure swing adsorption process for the separation of CO₂ and H₂ for example in the context of a pre-combustion CO₂ capture process, such as the integrated gasification combined cycle technology.