Physisorption of SO₂ by carbonaceous model adsorbents with tunable hierarchical pore configurations: Experiment and simulation

Adsorption removal of SO₂ using activated carbons has attracted enormous attention due to its relatively low water consumption and environmental friendliness. The physisorption of SO₂ is regarded as the prerequisite step of SO₂ chemisorption (i.e., SO₂ reacting with oxygen and moisture in the flue gas). In this study, a series of carbonaceous model adsorbents (i.e., activated carbons, ACs) with various pore hierarchy degrees and similar surface chemistry were synthesized by simply regulating the conditions of catalytic activation. The physical and chemical characteristics of the ACs were elucidated by N₂ physisorption, XPS, TEM and SEM. Both dynamic breakthrough performances and isotherms of SO₂ adsorption on ACs were investigated, presenting a negative correlation between pore hierarchy and SO₂ saturated adsorption capacity. Compared with the fitting of semi-empirical isotherm models, classical molecular dynamic (MD) simulation can better demonstrate the spatial distribution and the local density of SO₂ molecules in nanopores of ACs with diameters <2 nm.