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采用XAFS、XRD和DTA技术研究了化学还原法制备的超细NiB非晶态合金的结构及退火晶化行为 .结果表明 ,NiB非晶态合金的退火晶化分两步进行 :在 5 98K形成晶态的Ni3 B和纳米晶的Ni;6 5 2K退火导致Ni3 B分解以及纳米晶Ni聚集 .在6 2 3K退火处理后的NiB样品的苯加氢活性最高 .活性组分的苯加氢催化性能高低顺序为 :纳米晶Ni >超细Ni B非晶态合金 >晶态Ni.超细Ni B非晶态合金的活性中心主要为纳米晶的Ni和Ni富集的NiB非晶态 .超细NiB非晶态合金催化剂在反应过程中失活的原因主要是纳米晶Ni的聚集和积碳而所导致活性表面降低 .
The structure and annealing crystallization behavior of the ultrafine NiB amorphous alloy prepared by chemical reduction method were studied by X-ray diffraction (XRD), X-ray diffractometry (XRD) and DTA technique. The results show that the annealing crystallization of NiB amorphous alloy is carried out in two steps: Ni3B in crystalline state and nanocrystalline Ni; annealing in 652K resulted in the decomposition of Ni3B and the aggregation of nanocrystalline Ni. The NiB sample annealed at 623K had the highest hydrogenation activity of benzene.Hydrogenic catalysis The order of the performance is as follows: nanocrystalline Ni> ultrafine Ni B amorphous alloy> crystalline Ni. The active centers of the ultrafine Ni B amorphous alloy are mainly nanocrystalline Ni and Ni-enriched NiB amorphous The reason for the inactivation of the fine NiB amorphous alloy catalyst during the reaction is that the active surface is reduced due to the aggregation and carbon deposition of the nanocrystalline Ni.