Selective removal of SO2 over tertiary amine-containing materials

• Tertiary amine grafted pore-expanded MCM-41 was found to be highly selective for SO2 adsorption on in presence of CO2.
• High adsorption capacity of 2.19 mmol SO2/g at room temperature with 1% SO2.
• Adsorption capacity increased threefold under humid condition.
• The adsorbent was completely regenerated thermally after exposed to dry or humid SO2.

This work describes the application of a tertiary amine containing material, namely N,N-dimethylpropylamine-grafted pore-expanded mesoporous silica (TER-PE-MCM-41) for selective adsorption of SO2. The amine loading was 3.26 mmol/g. In the presence of 1% SO2/N2, the SO2 adsorption capacity was 2.19 mmol/g under dry condition at 23 °C, corresponding to a SO2/N ratio of 0.67. The adsorption took place presumably via formation of a charge transfer complex. The presence of water vapor had a positive effect on the adsorption capacity of SO2, which increased threefold in the presence of 32% relative humidity. The SO2-saturated adsorbents in both dry and humid conditions were fully regenerated at 130 °C under N2. The SO2 working capacity remained almost unchanged in consecutive adsorption/regeneration cycles. No measurable CO2 adsorption over TER-PE-MCM-41 was detected, and the presence of CO2 did not cause any adverse effect on SO2 uptake under dry or humid conditions.