Responsive Porous Material for Discrimination and Selective Capture of Low-Concentration SO2

The efficient removal of low-concentration SO2is of great significancebut challenging due to the competitive adsorption of CO2. Herein, we report theefficient capture of low-concentration SO2with high selectivity over CO2by Mn(INA)2(INA = isonicotinate) with a designed pore structure. Notably, the channels ofMn(INA)2exhibit large cavities and narrow bottlenecks, leading to the exclusion of thelarger molecules of N2and CH4. An interesting phenomenon was observed throughsingle-crystal X-ray diffraction experiments where SO2openedthe bottlenecks andentered the cavities via the rotation of the pyridine ring (12.2 degrees) to enlarge the cavitiesto accommodate SO2molecules. These responsive properties of Mn(INA)2to SO2molecules afford high SO2/CO2separation selectivity. In addition,first-principlesdispersion-corrected density functional theory (DFT-D) calculations elucidate that thehigh-density host-guest interactions including duple S delta+middotmiddotmiddotO delta-electrostatic inter-actions, multiple H delta+middotmiddotmiddotO delta-dipole-dipole interactions, and guest-guest interactionsbetween SO2molecules are responsible for the sensitive response of the material toward low-concentration SO2(2000 ppm). Theefficient SO2capture properties of Mn(INA)2are further demonstrated by the breakthrough experiments. Moreover, the material isstable and easy to scale up, which makes it promising for low-concentration SO2removal

Automated summary

This study reports the efficient capture of low-concentration SO2 with high selectivity over CO2 using Mn(INA)2 with a designed pore structure. The material exhibits large cavities and narrow bottlenecks, allowing for the exclusion of larger molecules and the accommodation of SO2 molecules. The high-density host-guest interactions contribute to the sensitive response towards low-concentration SO2. Breakthrough experiments further demonstrate the efficient capture properties of Mn(INA)2.