催化作用
壳体(结构)
化学工程
微型多孔材料
材料科学
介孔二氧化硅
煅烧
氢
过氧化氢
热稳定性
纳米晶
介孔材料
纳米技术
化学
复合材料
有机化学
工程类
作者
Myung Gi Seo,Dae Won Lee,Sang Soo Han,Kwan Young Lee
标识
DOI:10.1021/acscatal.7b00388
摘要
Many studies have been conducted on core–shell structured nanocatalysts thanks to their high thermal and physical stability. However, for a typical core–shell structure, shell thickness and pore size that affect mass transfer through the shell are difficult to control. Herein, we synthesized a different type of core–shell catalyst, in which a mesoporous silica shell encapsulates the Pd-nanocrystals-grafted-SiO2 nanobeads. With the preparation method introduced, we successfully controlled the thickness of the shell layer and generated a mesoporous texture over the shell layer. In activity tests, the production rate of hydrogen peroxide significantly increased when using the mesoporous shell catalyst over the microporous shell catalyst of similar shell thickness. The thickening of the mesoporous shell layer reduced the production rate of hydrogen peroxide. Thus, the thinner the thickness of a mesoporous shell, the more favorable in terms of pore-diffusion rate. However, the shell thickness should be adequately adjusted, because an extremely thin shell layer cannot protect the core Pd crystals from thermal agglomeration in a calcination and reduction process.
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