Nanosized Ni/SiO2 catalyst prepared by homogeneous precipitation in wet silica gel.
Nanosized Ni/SiO2 catalyst prepared by homogeneous precipitation in wet silica gel.
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通过在湿硅胶中均匀沉淀制备纳米Ni/SiO2催化剂。
DOI：
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发表时间：
2001
影响因子：
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通讯作者：
S. Yoshida
中科院分区：
文献类型：
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作者：
R. Takahashi;S. Sato;T. Sodesawa;N. Nakamura;S. Tomiyama;T. Kosugi;S. Yoshida
采用溶胶-凝胶法制备了Ni/SiO2催化剂。制备过程由两个连续步骤组成：在硝酸镍和尿素存在下在50 ℃下使二氧化硅凝胶化，然后在较高温度下老化，通常在80 ℃下老化，以分解尿素。尿素的分解增加了湿凝胶中溶液的pH，导致硅胶结构重排和镍物种沉积的同时发生。结果，二氧化硅的结构从分枝的聚合物网络变成颗粒聚集体，其将镍阳离子捕获在颗粒中。所得的Ni/SiO2含有大的中孔，其具有高达1000 ℃的高热稳定性，并且即使在20重量%的高Ni含量下也具有4 nm的典型微晶尺寸的高度分散的Ni金属颗粒。
A Ni/SiO2 catalyst was prepared by homogeneous precipitation of nickel hydroxide in a sol-gel-derived wet silica gel. The preparation process consists of two successive steps: gelation of silica in the presence of nickel nitrate and urea at 50 degrees C, followed by aging at higher temperature, typically at 80 degrees C, to decompose the urea. The decomposition of urea increases the pH of the solution in the wet gel, leading to the concurrence of structural rearrangement of silica gel and deposition of nickel species. As a result, the structure of the silica changes from a ramified polymeric network into particle aggregates that entrap the nickel cations in the particles. The resulting Ni/SiO2 contains large mesopores that have high thermal stability up to 1000 degrees C and highly dispersed Ni metal particles with typical crystallite size of 4 nm even at high Ni content at 20 wt%.