GAS SEPARATION AND PURIFICATION BY POLYMERIC ADSORBENTS - FLUE-GAS DESULFURIZATION AND SO2 RECOVERY WITH STYRENIC POLYMERS

High-surface-area polystyrenic sorbents possess all necessary properties for flue gas and tail gas desulfurization: high SO2 adsorption capacity and diffusion rate, high SO2/CO2 selectivity, and hydrophobicity. NO chemisorbs on these polymers at room temperature, but the NO-treated polymers retain all of the above properties. Model simulations show that pressure swing adsorption cycles using these NO-treated polymers can effectively remove well over 90% of the SO2 from the flue gases and, at the same time, generate SO2-concentrated desorption products containing well over 5% by volume Of SO2. The desorption products can be readily converted to elemental sulfur. Aromatic rings comprise the major fraction of the polymer surface area. Infrared spectroscopic analysis indicates that NO chemisorbs by interactions with the pi electrons in the aromatic rings on the polymer surface. The existence of lone-pair electrons in the SO2 molecule enables it to interact with the pi electrons of the aromatic rings much more strongly than CO2, leading to the high SO2/CO2 selectivity.