Adsorption of sulfur dioxide in carbon nanotubes - gravimetric experiment and molecular dynamics simulation

In this work, isothermal adsorption of sulfur dioxide (SO2) and nitrogen (N2) at carbon nanotubes (CNTs) is studied in molecular dynamics simulation and gravimetric experiments in the temperature range from 0°C to 125°C and the pressure range from vacuum to 80bar. The results are compared to each other and are in good agreement if the simulational data is adjusted by a scaling factor which is tied to the BET surface area of the respective CNTs. In simulation, single-walled CNTs in a diameter range of 1.48nm to 10.77nm are regarded. Additionally, graphene was simulated in the two gas atmospheres. For a CNT(20/20) mixtures of SO2 and N2 were also studied and show a high attraction for SO2. Adsorption experiments with multi-walled CNTs, single-walled CNTs and vertically aligned CNTs in SO2 show adsorbed amounts up to 22.7mmol/g. For N2 experiments the adsorbed amount is up to 1.49 mmol/g. From the adsorption isotherms heats of adsorption are derived. For SO2 data the heats of adsorption are in the range between 18 and 30 kJ/mol. For N2 data the heats of adsorption are in the range between 9 and 19kJ/mol. Evaluations of adsorption isotherms from simulation deliver comparable heats of adsorption