A comparative gas sorption study of dicarbazole-derived microporous hyper-crosslinked polymers

Abstract

Abstract Tailoring selective gas uptake properties of porous organic polymers is very crucial for their future use in gas separation and storage, however, unraveling the impact of polymerization methods and linkers while fixing the core of the polymers remains a great challenge. Here, a comparative study of three microporous networks synthesized by linking dicarbazole (4,4′-di(9H-carbazol-9-yl)-1,1′-biphenyl, YBN) building blocks with dimetoxymethane, dimetoxybenzene, and cyanuric chloride. Linkers for giving hypercosslinked, hypercosslinked-covalent and covalent triazine frameworks through FeCl3 and AlCl3 catalyzed Friedel–Crafts reactions have been presented. The resulting microporous polymers, namely YBN-DMM, YBN-DMB, and YBN-CC were fully characterized by spectral and analytical methods then comparatively tested for gas uptake (CO2, CH4, O2, CO, and H2) and selectivity (CO2/N2, CO2/O2, for CO2/CO and CO2/CH4) under ambient pressure and three different temperature. These obtained polymers exhibit high BET specific surface area up to 968\u202fm2 and predominantly ultramicroporous character, and remarkable thermal (up to 350\u202f°C) and chemical stability in various solvents including concentrated hydrochloric acid. According to the linker, polymers have high gas uptake properties reaching 12.66\u202fwt % CO2, 1.64\u202fwt%. CH4, 1.04\u202fwt% CO adsorption at 1\u202fbar/273\u202fK and 1.59\u202fwt % H2 adsorption at 1\u202fbar/77\u202fK with interesting N2-phobia down to 0.04\u202fwt% with relatively O2 phobia down to 0.22\u202fwt% at 1\u202fbar/320\u202fK respectively. According to IAST calculations, it was observed that the selectivity properties, especially required for post-combustion processes at high pressures and temperatures, increase unusually by changing the linkers reaching up to 159 for CO2/N2, 63.5 for CO2/O2, 63.76 for CO2/CO, 7.47 for CO2/CH4.