Covalent Triazine Frameworks with Palladium Nanoclusters as Highly Efficient Heterogeneous Catalysts for Styrene Oxidation

 Catalytic oxidation of styrene has attracted extensive attention in industries and academia. Benzaldehyde, one of the derived valuable aromatic aldehyde oxidation products, has been extensively applied in the perfume, pharmacy, and dye industries. However, it is difficult to achieve a high yield by transforming styrene into benzaldehyde with a sustainable supply of active catalysts. Furthermore, conventional catalyst species inevitably suffer permanent catalytic failure, which largely limits the product yield. Covalent triazine frameworks (CTFs) have emerged as an excellent platform for heterogeneous catalysis due to their regular pore channels and large specific surface area. Herein, we report the use of a CTF loaded with Pd clusters (DCP-CTF@Pd-MC) with a heteropore structure to oxidize styrene into benzaldehyde. The obtained DCP-CTF@Pd-MC with high catalytic stability is easy to recycle and shows excellent catalytic activity. The striking catalytic performance, with a high product yield of 95%, can be attributed to the heteropore structure anchoring more exposed active sites. The strong coordination of the pyridine nitrogen atoms in the catalyst frameworks with Pd clusters enables better chemical stability, especially in catalytic reactions. Moreover, well-provided transport channels can accelerate mass transfer between the reactants and products.