Cationic cellulose nanofibrils as a green support of palladium nanoparticles: catalyst evaluation in Suzuki reactions

Cationic cellulose nanofibrils (C-CNF) were used as a support for the growth and the immobilization of Pd NPs using PdCl₂ as precursor. The ensuing Pd@C-CNF nanocomposite was tested as a catalyst for the Suzuki coupling reactions between aryl halides and arylboronic acid. Several characterization methods including TEM, HR-TEM, XRD, FT-IR, TGA and XPS were used to confirm the immobilization of Pd NPs onto the C-CNF surface and probe the surface composition after interaction with PdCl₂. A quasi total coupling of phenyl boronic acid and 4-bromoacetophenone in DMF at 110 °C was found to occur after 4 h when only 0.02% of Pd@C-CNF of catalyst was used. Furthermore, the Pd@C-CNF could be easily recovered and reused for three consecutive Suzuki reaction cycles without significant loss of its catalytic activity and the loaded percent of palladium nanoparticles was maintained.