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.

The activation of peroxymonosulfate (PMS) by cobalt?based catalysts has the advantages of high catalytic activity, simple operation, easy recyclability, and low cost. Hence, it has attracted much attention in the field of advanced oxidation processes in recent years. This paper reviewed typical methods for the synthesis of cobalt?based catalysts, including solid phase, gas phase, and liquid phase methods. Several types of cobalt?based catalysts for PMS activation, including cobalt oxides with special morphologies, supported cobalt catalysts, and cobalt?based composite metal oxides, were summarized. The applications of these cobalt?based catalysts in environmental remediation via PMS activation were also elaborated, such as the degradation of organic dyes, endocrine?disrupting chemicals, and pharmaceutical and personal care products. Finally, the current shortcomings of cobalt?based catalysts in PMS activation were summarized, and some future research directions in this area were proposed.