Study On Preparation And Hydrogenation Performance Of Aromatic Nitro Compounds Of Pt-bimetallic Catalysts

Highly efficient synthesis different products of aromatic nitro compounds under mild conditions is a challenging subject. Bimetallic catalysts exhibit good catalytic performance due to the strong interaction between bimetallic and modified surface geometric arrangement and electronic properties. On the basis of previous work, Pt-bimetallic catalysts were prepared by absorb-reduction method, and investigated their hydrogenation catalytic performance of aromatic nitro compounds. The main results have been summarized as follows:1. Au-Pt/SiO2 catalysts exhibited excellent catalytic performance in the hydrogenation of p-chlorine nitrobenzene (p-CNB) to obtain the p-chlorine nitrosobenzene. The conversion of p-CNB was as high as 76.7% and the selectivity of p-chlorine nitrosobenzene was 38.2% under the condition of 50?,0.5 MPa H2, n-hexane as solvent. The results of XRD and STEM-EDX characterizations showed that highly dispersed Au-Pt bimetallic nanoparticles were prepared, which was probably responsible for the good catalytic performance of Au-Pt/SiO2 catalyst.2. Ni-Pt/SiO2 catalysts exhibited good catalytic performance in the hydrogenation of p-CNB to obtain the p-chlorine azobenzene. The conversion ofp-CNB was 98.3%, the selectivity of p-chlorine azobenzene was 84.9%. The TOF was up to 6500h-1 under the condition of 50?,0.5 MPa H2, ethanol as solvent, reaction time for 30 min, which is higher than that of the reported catalysts. The results of TEM, STEM-EDX, XPS characterizations showed that there was strong interaction between highly dispersed Ni and Pt nanoparticles. Electronics offset from Ni to Pt reduced the oxidation of Ni and Pt. The increase of the active sites facilitate highly efficient synthesis of aromatic azo compounds over Ni-Pt/SiO2 catalysts under mild conditions.3. By changing the reaction conditions, Ni-Pt/SiO2 bimetallic catalysts can highly efficient synthesis different products of aromatic nitro compounds:azo compounds, azoxy compounds, or arylamine.