Densification of Silica Spheres: A New Pathway to Nano-Dimensioned Zeolite-Based Catalysts.
Densification of Silica Spheres: A New Pathway to Nano-Dimensioned Zeolite-Based Catalysts.
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DOI：
10.1002/chem.201702768
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发表时间：
2017-08
期刊：
影响因子：
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通讯作者：
A. Machoke;B. Apeleo Zubiri;R. Leonhardt;V. Marthala;M. Schmiele;T. Unruh;M. Hartmann;E. Spiecker;W. Schwieger
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文献类型：
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作者：
A. Machoke;B. Apeleo Zubiri;R. Leonhardt;V. Marthala;M. Schmiele;T. Unruh;M. Hartmann;E. Spiecker;W. Schwieger
纳米材料预计将在未来催化工艺的开发中发挥独特的作用。在此，将预先制备的和几何形状良好限定的无定形二氧化硅球致密化成具有纳米尺寸的富含二氧化硅的沸石。在致密化之后，所获得的纳米尺寸的沸石表现出与起始前体相同的球形形态，但其特征在于尺寸急剧减小、密度更高和结晶度高。通过对较大前体颗粒进行良好控制的蒸汽辅助处理，实现向结晶沸石材料的相转化和致密化效果，使得转化过程始终朝向球体的中心进行，就像收缩过程一样。此外，该方法也适用于市售二氧化硅颗粒以及含铝体系（前体），从而产生具有改进的催化性能的酸性纳米催化剂。
Nanosized materials are expected to play a unique role in the development of future catalytic processes. Herein, pre-prepared and geometrically well-defined amorphous silica spheres are densified into silica-rich zeolites with nanosized dimensions. After the densification, the obtained nanosized zeolites exhibit the same spherical morphology like the starting precursor but characterized by a drastically reduced size, higher density, and high crystallinity. The phase transformation into crystalline zeolite material and the densification effect are achieved through a well-controlled steam-assisted treatment of the larger precursor particles so that the transformation process proceeds always towards the center of the spheres, just like a shrinking process. Furthermore, this procedure is applicable also to commercially available silica particles, as well as aluminum-containing systems (precursors) leading to acidic nano-catalysts with improved catalytic performance.