Constructing nitrogen-doped porous organic polymer- supported single-atom cobalt catalysts for highly efficient hydroformylation of internal olefins

Designing low-cost and highly efficient heterogeneous catalysts for olefin hydroformylation, particularly utilizing abundant internal olefins, represents a research area of considerable scientific and industrial significance. Herein, a series of N or P doped porous organic polymers (POPs-N&P) are designed and fabricated to serve as carriers by the solvothermal polymerization of vinyl functionalized amine-type N, pyridinic N, imidazole N and PPh 3 ligands. The microenvironments surrounding cobalt were effectively regulated in Co/POPs-N&P catalysts. Specifically, single atom Co/POPs-NPh 3 catalyst with amine-type N chemical configurations possesses superior olefins isomerization abilities, thereby presenting an excellent 2-octene conversion of 95.9 % with the oxygenates selectivity of 62.6 % and a turnover number of 561, outperforming most of heterogeneous cobalt-based catalysts reported to date. Experimental results verify that distinct electronic environment of Co sites lead to different olefins isomerization abilities. Abundant Co N active species are generated on the Co/POPs-NPh 3 catalyst, which are different with those active species produced on the Co/POPs-PPh 3 , Co/POPs-Im&DVB and Co/POPs-Py&DVB catalysts. Furthermore, a reaction mechanism was also suggested for 2-octene hydroformylation over the Co/POPs-NPh 3 catalyst. This work underlines the potential of POPs as an ideal platform for the modulation of the coordination environment of the Co sites toward improved hydroformylation of internal alkenes.