Trace SO2 Gas Capture in Stable 3D Viologen Ionic Porous Organic Framework Microsphere

Eliminatingtrace sulfur dioxide (SO2) using nanoporousadsorbents is industrially preferred yet of great challenge due tothe competitive adsorption of CO2. Herein, we reporteda highly stable 3D viologen porous organic framework (Viologen-POF)microsphere via one pot polymerization reaction of 4,4 '-bipyridineand tetrakis(4-(bromomethyl)phenyl)methane. Compared to the previouslyreported irregular POF particles, viologen-POF microsphere shows bettermass transfer uniformity. Owing to the intrinsic separated positiveand negative electric charges center in viologen-POF microspheres,it exhibits excellent SO2 selective capture performance,which can be collaboratively confirmed by static single-componentgas adsorption, time-dependent adsorption rate, and multicomponentdynamic breakthrough experiments. Viologen-POF exhibits high SO2 absorption capacity (1.45 mmol g(-1)) atultralow pressure of 0.002 bar and high SO2/CO2 selectivity of 467 at 298 K and 100 kPa (SO2/CO2, 10/90, v/v). The theoretical calculations based on density functionaltheory (DFT) and DMol(3) modules in Material Studio (MS)were also performed to elucidate the adsorption mechanism of viologen-POFtoward SO2 at the molecular level. This study representsa new type of viologen porous framework microsphere for trace SO2 capture, which will pave the way on the applications of ionicPOF for toxic gas adsorption and separation.