An insight into the catalytic hydrogenation mechanism of modified dendrimer-loaded rhodium ionic catalyst for unsaturated copolymer
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A catalytic mechanism of ionic rhodium catalyst stabilized by macrcycles-modified dendrimer (G2-M(Rh3+)) for the hydrogenation of unsaturated copolymer was proposed. It was found that the co-catalyst of triphenylphosphine (PPh3) possessed significant influence on the catalytic hydrogenation activity of G2-M(Rh3+). An active specie of [Rh(PPh3)3]+ could be generated from a ligand exchange between G2-M(Rh3+) and PPh3 during the hydrogenation process, which could outstandingly improve the selective hydrogenation activity for unsaturated co-polymers. Totally different from other catalyst for hydrogenation, the active [Rh(PPh3)3]+ was reduced to Rh0 nanoparticles which could be further recaptured by the non-coordinated macrocycles in G2-M after hydrogenation. The Rh0 recapture could significantly reduce Rh residues in the hydrogenated co-polymers. This research can give an insight into the interaction of dendrimer-loaded Rh and the co-catalyst of PPh3 during hydrogenation processs.
KeywordsCatalytic hydrogenation; mechanism Rhodium catalyst Unsaturated co-polymer
This work was supported financially by the National Natural Science Foundation of China (Project No. 51273071).
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Conflict of interest
The authors declare that they have no conflict of interest.
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