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Cholerny Spammer
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 Posted: Sun 18:23, 28 Nov 2010 Post subject: ugg boots ireland Nickel oxide on the surface of t |
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Nickel oxide on the surface of the activated alumina dispersion and the bulk dispersion - the preparation method on the dispersion of Ni-Al dispersion and structure of state
Ming Ni ions into the tetrahedral cavities require a high activation energy. 3) the structural characteristics of the surface state dispersion prepared by impregnation at low temperature and high temperature treatment and by co-precipitation method to prepare NiO/AI2O3 system, not only the dispersion threshold is different from the radial structure function is also quite different. Figure 6. Low dispersed Ni. Ni base is BB ligand coordination,[link widoczny dla zalogowanych], coordination with the peak load increased and regularly increased. 1f1. Ni2 +-Ni distance large compared with the normal spinel, and coordination with the NiOq ~ proximity, or equivalent. This once again shows TNi ions tend to form 0002004006008001000 Figure 6 coprecipitation and impregnation Al2o3 prepared NiO/AI2O3 of radial structure function of the comparison, 1200 ℃ ... ... ... \... _-_ Baking: 700 ℃; - total precipitation: 1200 ℃ A dip sample load 0.099gNiO/gy-A1203: B impregnated samples load 0.499gNiO/gy-AI203; co-precipitation sample load 0. 111gNiO/gy-AIaO3 load 0.497gNiO/gy-AI203 precipitation samples and the NiO in the same octahedral coordination,[link widoczny dla zalogowanych], and on the surface more easily than in bulk form such coordination, which may be due to the surface smaller space constraints, the reason has more degrees of freedom. Further results also show that the surface of dispersion may be discrete,[link widoczny dla zalogowanych], it may be a certain Ni-Ni coordination structure, the surface can accommodate only smaller, but also can accommodate a considerable number of scattered Ni ions. With the calcination temperature, Ni radial structure function changes with the load situation has obviously changed. at a very low loading sample was 800 \Ni coordination peaks at lower temperatures rather than the surface of dispersed Shihai high, and higher when the load is reduced. This shows that when the bulk is not scattered scattered like to imagine a more discrete surface area, Ni ions away from each other It has some Ni.Ni tends to form the structure of coordination. Third, the conclusion 1. coprecipitation samples, small particles due to the formation of precipitation, prone to generate solid solution interaction. 1112.y-Al203 or intended boehmite impregnated samples at 450 ℃ for treatment, can not make Ni ions into the 1,. AI203 solid solution generated the bulk, Nio can only be distributed on the surface, scattered small amount. Only after the 80O ℃, Ni ions to enter Al203 formed within the solid solution, and to increase the amount distributed. 3.Ni ions into the body of Ah-Al2O3 solid solution phase into the octahedral sites when the lower activation energy required in 700.800 \can enter 1,. AI2O3 tiny octahedral sites within the grain,[link widoczny dla zalogowanych], and the formation of solid solution. is not the same structure and NiAI204. Ni into the tetrahedral position requires a high activation energy and high temperature. even after the l200 ℃ treatment, low Ni loading of samples, Ni is also the first into the octahedral cavities, were octahedral. Only when a higher load, Ni ions before entering the tetrahedral position. 4. either impregnation or coprecipitation of solid solution, and regardless of the reasons for the formation of solid solution is the majority carrier of the surface of the surface contraction, or ion diffusion and interactions in the solid solution distribution of Ni ions is not random and uniform, the surface of ceramic particles and in vivo distribution of Ni ions may be very different, Ni ceramic particles may enter the area around 30A below the surface, forming a rich Ni layer. Acknowledgements: This study funded by the NSFC, and Beijing and Beijing Laboratory BEPc Tian Tian laboratory dynamic steady state , we wish to thank. References 【1】. I.J.KitchenerandD.C.Puxley, \, C.KomodromosandN.D.Parkyns, Thepreparationofcatalysts (Il1) 【3】 Zhi-Guo Ren, Peking University, master's thesis, June 1997 112
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