A novel nanoscale catalyst system composed of nanosized Pd catalysts immobilized on Fe3O4@ SiO2-PAMAM

This study reports the syntheses of Fe3O4@ SiO2-Gn-PAMAM-Pd(0) composites and their applications as magnetically recoverable catalysts for the hydrogenation of allyl alcohol. The controlled growth of polyamidoamine (PAMAM) dendrimers with different generations on Fe3O4@ SiO2 surfaces was monitored by FT-IR spectra. Subsequently, Pd nanoparticles with diameters of about 2.5 nm were stabilized homogeneously on the surface of Fe3O4@ SiO2-Gn-PAMAM (n = 1-4), investigated by thermogravimetry (TG) and transmission electron microscopy (TEM) measurements. The Fe3O4@ SiO2-Gn-PAMAM-Pd(0) have high catalytic activity for the hydrogenation of allyl alcohol and the rate of the reaction can be controlled by changing the generation of PAMAM. In particular, the composites made of superparamagnetic Fe3O4 nanocrystals with diameters of about 10 nm are very suitable as catalyst supports for catalyst separation under a relatively low external magnetic field and catalyst re-dispersion after removing the external magnetic field.