High capacity gas capture and selectivity properties of triazatruxene-based ultramicroporous hyper-crosslinked covalent polymer

Authors: ALİ ENİS SADAK

Abstract: Tuning the selective sorption features of microporous organic networks is of great importance for subsequent applications in gas uptake and hiding, while it is more attractive in terms of being both time and cost effective to realize these optimizations without using functional groups in the core and linker. "Knitting" is one of the easiest and most used method to obtain a broad scope of hyper-crosslinked polymers on a large scale from aromatic structures that do not contain functional groups for polymerization. By the use of Knitting method, a hypercrosslinked covalent ultramicroporous organic polymer was obtained via stepwise process from using triazatruxene (TAT) as core -a planar indole trimer- through anhydrous FeCl₃ catalyzed Friedel-Crafts alkylation using dimethoxybenzene as a linker. The resulting microporous polymer, namely TATHCCP was completely identified by analytical and spectral techniques after examined for gas properties (CO₂, CH₄, O₂, CO, and H₂) and selectivity (CO₂/N₂, CO₂/O₂, for CO₂/CO and CO₂/CH₄) up to 1 bar and increased temperatures (273 K, 296 K and 320 K). Although it has a relatively low (Brunauer-Emmett-Teller) BET specific surface area around 557 m2/g, it was seen to have a high CO₂ capture capacity approaching 10% wt. at 273 K. In accordance with (ideal adsorbed solution theory) IAST computations, it was revealed that interesting selectivity features hitting up to 60 for CO₂/N₂, 45 for CO₂/O₂, 35 for CO₂/CO, 13 for CO₂/CH₄ at lower temperatures revealed that the material has much better selectivity values than many HCP (hyper-crosslinked polymer) derivatives in the literature even from its most similar analog dimethoxymethane derivative TATHCP, which has a surface area of 950 m²/g.

Keywords: Friedel-Crafts, IAST (ideal adsorbed solution theory), microporous organic polymer, triazatruxene, hyper-crosslinked polymers, gas uptake

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