Unraveling surface basicity and bulk morphology relationship on covalent triazine frameworks with unique gas adsorption and catalytic properties

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 [1]. 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 (Scheme 1). The adopted synthetic conditions along with the selected dicyano-precursor, 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 steam-free direct dehydrogenation (DDH) of ethylbenzene into styrene and b) the selective and highly efficient adsorption of CO2 and H2. We have demonstrated, for the first time, that CTFs are valuable candidates to promote DDH efficiently, outperforming the industrial benchmark K-Fe catalyst and ranking among the best catalytic metal-free systems reported so far [2]. Notably, chemically accessible surface basicity as a key factor for the inhibition of the catalyst deactivation has been unveiled for the first time. Finally, these high-surface area and N-rich materials have demonstrated unique features for H2 storage and CO2 capture and sequestration [3].