Adsorption isotherms of SO2 in air on hydrophobic dealuminated Y (DAY) zeolite and silicalite at SO2 partial pressures ranging from 0.5 to 5 kPa were measured by the gravimetric method. The SO2 sorption isotherms on these two zeolites at different temperatures (25–100 °C) can be correlated by the Langmuir equation at low SO2 pressures (<2 kPa) and by the Freundlich equation in the whole SO2 pressure range studied. The sorption capacity of SO2 on silicalite is larger than that of the DAY zeolite. Selective surface adsorption rather than the pore-filling mechanism was observed on adsorption equilibrium in these two zeolites. The SO2 sorption and desorption kinetic data obtained on these two zeolites show the dominant role of the reaction of SO2 on the zeolite surface in the SO2 sorption or desorption process. The simple Langmuir adsorption kinetic model provides a good description of SO2 sorption and desorption kinetics on these two zeolites at low SO2 partial pressures. The thermal stability of these two zeolites was studied by comparing the pore texture, crystalline structure, and SO2 adsorption ability of the fresh samples with those of the thermally treated samples at 550 or 850 °C under various caustic conditions. It was found that these two zeolites are thermally and chemically stable under the studied conditions.
ASJC Scopus subject areas
- Chemical Engineering(all)
- Industrial and Manufacturing Engineering