Improvement of temperature profiles using variable heat of adsorption in modeling H2/CO2 breakthrough experiments

Pressure swing adsorption (PSA) technology is widely applied to hydrogen purification from mixed gas. This article mainly studies the adsorption dynamics, breakthrough behavior, and temperature profiles of the typical H-2/CO2 mixture by activated carbon in the adsorption bed. Based on the Comsol Multiphysics simulation platform, a one-dimensional multicomponent adsorption, heat and mass transfer modeling is established and validated by published data of H-2/CO2 adsorption breakthrough experiments. By comparing the simulated data with the experimental data, it is found that the breakthrough curves are in good agreement, but the temperature profiles are not fit perfectly. After a comprehensive literature review, we found that the heat of adsorption dramatically influences the temperature profiles. The constant heat of adsorption has limitations for modeling breakthrough experiments. A variable heat of adsorption was proposed and applied to improve the temperature profiles. The results show that the variable heat of adsorption can effectively improve the temperature profiles in the gas adsorption process, and it works well for different adsorption temperatures, pressures, and compositions. The variable heat of adsorption instead of the constant heat of adsorption can significantly increase the peak value of the temperature profiles to be more consistent with experimental results. The relative deviations between the simulated and experimental values of the temperature profiles are reduced from 11.42% to 1.47% using the variable heat of adsorption. The simplification form of the Clausius-Clapeyron equation gives the outline and trend of the correlation between the heat of adsorption and the amount of adsorption for different adsorption temperatures, pressures, and compositions.

Automated summary

This article investigates the adsorption dynamics, breakthrough behavior, and temperature profiles of hydrogen purification using activated carbon. The results show that variable heat of adsorption can effectively improve the temperature profiles and make them more consistent with experimental data.