Pelletizing highly porous covalent triazine framework under mild conditions and applying it as adsorbent for Ru3+ ions

Abstract

CTFs (Covalent triazine frameworks) exhibit exceptional porosity and the ability to incorporate hetero-atoms (e.g. Ru) into their microstructures makes them versatile for several applications. However, pelletized form of the catalysts is required for various industrial processes. Although there are several methods available for pelletizing catalysts, but porosity of the pelletized CTF particles is compromised by applying these processes. In this study, CTF was synthesized by polymerizing Terephthalonitrile (TN) and pelletizing it by using Polystyrene (PS) and PVP. In CTF-PS composites, CTF particles were interconnected by PS microfibers with thickness ranging from 3 to 230 μm, while PVP and CTF were bonded by weak Van der Waals bonding. BET analysis showed Type-I isotherms for CTF-PS, and CTF-PVP composites, indicating that the materials were typically microporous, with an average pore size of ∼2 nm. Surface area values for the CTF-PVP, and CTF-PS were measured as 1128.7, and 610.81 m2g-1, meanwhile, pore volumes for the same were recorded as 0.532, and 0.291 cm3g-1, respectively. Owing to the small amount (10 %) of PVP in its composites CTF-PVP pellets retained most of the pores, maintaining almost 80 % of the porosity but could not remain intact in protic solvents. However, the CTF-PS pellet demonstrated excellent stability in protic solvents, making it suitable for support for the Ru catalyst or Ru extraction from solution. At 60 °C, by using 500 μM solution of RuCl3.3H2O 26 % of Ru was attached to the CTF-PS pellet, which can be an excellent prospect for lab scale catalytic reaction or industrial application.