以碳纳米管为模板合成的带有介孔和微孔的ZSM-5分子筛具有不同的复合结构。用三氯乙酸(TCA)可选择性地将中孔的铝脱除。基于TCA分子大小，它可能只扩散到中孔中，因而使得微孔部分不脱铝。从分子筛结构中脱除铝原子导致催化剂中出现中空的空间。若将硅原子填充到空位中，那么介孔部分的结构会变得与硅酸盐类似，不具有催化性能。本文使用含硅的溶液来填充空位，将硅原子直接取代中孔结构中的铝原子。通过此特殊方法改变微孔和介孔的几何形状和性质，从而使改性HZSM-5上的积碳量从14%降低至3%。
Composite structures of ZSM‐5 zeolites were prepared by the synthesis of mesopores and mi‐cropores using carbon nanotubes as a template. Dealumination of mesopores was performed selec‐tively using trichloroacetic acid, which could only diffuse into the mesopores and not the mi‐cropores owing to the size of the trichloroacetic acid molecules. Empty spaces are created in the catalyst as a result of removal of the Al atoms from the zeolite structure. If Si atoms fill the empty space, then the structure of the mesopores becomes similar to silicates, which do not have any cata‐lytic properties. Silicon containing solution was used to fill the empty spaces, and in doing so, a unique method was developed, by which silicon atoms can directly replace the extracted Al atoms from the mesopore structure. Therefore, by changing the geometry and properties of the mesopores and micropores, the amount of coke reduced from 14%for HZSM‐5 to 3%for the modified zeolite.
参考文献
| [1] | J.A. Botas;D.P.Serrano;A.Garcia.Catalytic conversion of rapeseed oil into raw chemicals and fuels over Ni- and Mo-modified nanocrystalline ZSM-5 zeolite[J].Catalysis Today,20121(1):59-70. |
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