A new
porphyrin-based cyanate monomer 5,10,15,20-tetrakis(4-cyanatophenyl)-porphyrin
(TCP) was synthesized, from which a porous polycyanurate network PCN–TCP
was constructed by means of one-step thermal cyclotrimerization reaction.
The substantial porphyrins in the PCN–TCP network enable the
coordination with cobalt (Co) ions to create a cobaltoporphyrin-supported
porous catalyst (Co@PCN-TCP) with a BET surface area of 689 m2 g–1 and ultramicropores (0.55 nm), micropores
(1.15 nm), and mesopores (2.11–5.23 nm). At 273 K and 1.0 bar,
Co@PCN-TCP uptakes 13.0 wt % CO2 with a high CO2/N2 selectivity (IAST, 79.1). Using Co@PCN-TCP as a heterogeneous
catalyst, high conversions for cycloaddition reactions between CO2 and various epoxides are achieved. Particularly, silicon-
and sulfite-containing cycloaliphatic di- and tri-epoxides with a
large molecular volume and steric hindrance also readily react with
CO2 to obtain the corresponding cyclic di- and tri-carbonates
with satisfactory conversions of 91.6–92.1 and 89.4%, respectively.
The resultant novel cyclic di- and tri-carbonates are potential raw
materials for producing isocyanate-free polyurethanes. In addition,
the reaction conversions are almost unchanged after repeatedly using
Co@PCN-TCP, exhibiting excellent recovery and reusability.