2D Nitrogen-Rich Covalent Triazine Frameworks as Highly Versatile and Effective Metal-Free Platforms For Catalysis and Gas-Storage

Porous organic polymers (POPs) have recently gained great attention thanks to their peculiar features such as their large surface area and their superior thermal and chemical stability. Among them, Covalent Triazine Frameworks (CTFs) represent a class of nitrogen-rich POPs with highly tunable chemical composition and porosity that make them potentially valuable candidates for gas capture/storage and for application in catalysis. CTFs are commonly prepared by dynamic trimerization reaction of aromatic nitriles in ionothermal conditions; in this study, 1,3-dicyanobenzene and 2,6-dicyanopyridine are selected as the starting building blocks for the synthesis of CTFs at various temperatures. The adopted synthetic conditions along with the selected dicyano-precursors, allow to tune the final materials porosity and N-content. The as-prepared CTF samples are completely characterized before being successfully used as metal-free systems for: a) the catalytic steam-free and oxygen-free direct dehydrogenation (DDH) of ethylbenzene (EB) into styrene (ST) and b) the selective and highly efficient adsorption of CO2 and H2. Thanks to their unique chemico-physical and morphological properties, the CTF samples have been engaged for promoting one of the most important industrial processes for the production of a raw material at the heart of polymer synthesis. We have demonstrated, for the first time, that CTFs are valuable catalyst candidates to promote the process efficiently, outperforming the industrial benchmark K-Fe catalyst and ranking among the best catalytic metal-free systems reported in the literature so far. In addition to that, selected CTF samples from this series have demonstrated unprecedented CO2 and H2 adsorption properties respect to the related systems of the state-of-the-art, with CO2 and H2 uptakes up to 16.7 and 2.6 wt% at 298 and 77 K, respectively, at ambient pressure. The catalytic and adsorption properties of the above mentioned CTFs will be discussed in details along with their chemico-physical and morphological features.