As palladium(Pd) catalysts have poor selectivity to the target product in the selective hydrogenation process,a series of PdM/C bimetallic alloy catalysts were synthesized by the simple co?reduction of second metals (M=Mn,Fe,Co,Ni) and Pd. With 3?nitrostyrene as the model molecule and H2 as the hydrogen source, this study investigated the effect of second metals on the selective hydrogenation performance of Pd?based catalysts. The Pd?based catalysts were characterized and tested by methods including X?ray diffraction (XRD), transmission electron microscope (TEM),and gas chromatography.The results reveal that when pure Pd/C is used as the catalyst, the conversion reaches 100% for 1.5 h, but the selectivity of 3?nitrophenylethane is only 29%, and the selectivity of 3?aminophenylethane is 71%. After the introduction of second metals, the selectivity of 3?nitrophenylethane is increased to 75%~100% under the same conditions. Among them,PdFe/C has the best performance(100%) in the hydrogenation of 3?nitrostyrene to 3?nitrophenylethane, and high conversion(100%) and selectivity (99%) of 3?nitrophenylethane can still maintain after ten reaction cycles. It can effectively avoid over?hydrogenation and realize the selective hydrogenation of 3?nitrostyrene to 3?nitrophenylethane.
