Investigation Of Preparation And Catalytic Activity Of Pd-Ni Nanobimetallic Catalyst

Bimetallic nanoparticles are metallic entities comprising of atoms of two different metallic elements. Compared with monometallic nanoparticles, bimetallic nanoparticles are of special interest for several reasons. Firstly, they may serve as models for studying the formation of different alloys. Secondly, these bimetallic particles may have more varied properties than monometallic particles as various combinations are possible. It is well established that the catalytic properties of the monometallic nanoparticles, including activity, selectivity or resistance to deactivation, can be altered by the addition of the second metal. Thirdly, bimetallic particles could have particular structures not seen in bulk alloys, such as core-shell, cluster-in-cluster, separate, random structures, etc. Lastly, it is possible it is possible to save the precious metals by optimizing the synthesis conditionsNickel nanoparticles were prepared by rapid microwave(MV) heating of ethylene glycol solutions of NiCl2 with PVP as the protecting agent and hydrazine hydrate as the reducing agent, and characterized by UV-vis, TEM, and XRD. The average size of the nanoparticles can be controlled between 50 nm to 100 nm by changing the concentration of PVP, hydrazine hydrate and NaCO3. The resluts indcated the method of rapid microwave heating was prefer to traditional heating due to its better repeatability, homogeneity and dispersity, etc. Pd-Ni bimetallic nanoparticles were also prepared by rapid microwave(MV) heating and the average size of the bimetallic nanoparticles obtained diminished evidently by the addition of Palladium. And the everage size of Pd-Ni bimetallic nanoparticles can be controlled to between 1.82 nm to 8.51 nm by changing the condition of reaction and the molar ratio of Palladium to Nickel. TEM investigation showed that the everage size of Pd-Ni bimetallic nanoparticles increased with increasing Nickel content.Furthermore,Pd-Ni bimetallic nanoparticles were prepared with NaBH4 as the reducing agent and tetraethylene glycol as the solvent. The average size of the solvent stabilized Pd-Ni bimetallic nanoparticles can be controlled between 1.88 nm to 3.56 nm by changing the condition of reaction and the molar ratio of Palladium to Nickel. The TEM results showed that their average size increased with increasing Nickel content, this is similar to the Pd-Ni bimetallic nanoparticles prepared by rapid microwave heating. In the last chapter, the catalytic hydrogenation activity of solvent stabilized Pd-Ni bimetallic nanoparticles was investigated and reported. The results showed that the catalytic hydrogenation activities for cyclohexene and soybean oil of the solvent stabilized Pd-Ni bimetallic nanoparticles are very high compared to that of the conventional catalyst. The activity did not decreased sharply by lower Palladium content when it was > 50%.