Preparation And Properties Of Nickel-based Catalysts For Degrading Hydrazine Hydrate

With the continuous development of industry,hydrazine hydrate wastewater is discharged into the water,causing serious pollution to the water environment system and endangering human health.At present,the research on hydrazine hydrate wastewater is a hot issue.Nickel-based catalysts,as a new type of nano-catalytic materials,are widely used in industrial catalytic processes due to their high activity and low cost.In this paper,a series of Ni/Nd2O3 and Ni/Ce02 catalysts were prepared by hydrothermal method.Their catalytic properties were characterized by XRD,TEM,XPS and TG.Morphology,crystal structure,surface element valence state and thermal stability were characterized.The characterization of Ni/Nd2O3 and Ni/CeO2 shows that Ni exists as a face-centered cubic Ni0 crystal in the catalyst and the rare earth element exists in the amorphous state of its corresponding oxide.Rare earth oxides play a catalytic role in improving catalyst dispersibility,Increase the surface area of the role.The catalysts prepared at different hydrothermal time and hydrothermal temperature showed that the hydrothermal temperature and time had a great influence on the crystallinity and grain size of the crystals.The best crystallinity was obtained at 8h and 120?,and the particle size is uniform,the activity and selectivity of the catalyst for hydrazine hydrate degradation in the catalyst can be improved.The effects of molar ratio of rare earth elements to nickel,hydrothermal time and hydrothermal temperature on the performance of the catalysts for hydrazine hydrate reduction were investigated.The results showed that the active components in the Ni/Nd2O3 and Ni/CeO2 catalysts were Ni,rare earth oxides The substance acts as a dispersant and a carrier.Ni/Nd2O3catalyst is the best catalyst for the catalytic degradation of hydrazine hydrate when the molar ratio of Ni/Nd is 94:6,and the optimal reaction temperature is8h,120?.At this time,Ni/Nd2O3catalytic degradation of hydration Hydrazine has a hydrogen selectivity of 95%and a switching frequency of 39.4 h-1.For Ni/CeO2 nanoparticles,the molar ratio of Ni to Ce is 9:1 and the hydrothermal conditions are 8h.At 120?,the catalyst has the best effect of hydrazine hydrate degradation,with a hydrogen selectivity of 92.7%and a conversion frequency of 38.2h-1.The stability test of Ni/CeO2 catalyst shows that the catalyst is relatively stable,and the catalyst selectivity is still over 85%after 5 cycles.Based on the Ni/Nd2O3 and Ni/CeO2 catalysts,we investigated the influence of other transition metals(Mo,Fe,Cu,Co)on the catalysts.Characterization results show that the addition of other transition metals in Ni/Nd2O3 and Ni/CeO2 does not change the crystal structure,Mo,Fe and other elements in the amorphous form of the catalyst exists,after adding Mo catalyst grain size significantly smaller,The specific surface area increases,more active sites are exposed to the outside,which shows higher activity and hydrogen selectivity in the catalytic degradation of hydrazine hydrate.Compared with Mo,after addition of Fe,Cu and Co,the catalyst grain size Become larger,the catalytic activity in the hydrazine hydrate degradation smaller than before without doping.