Densification of Silica Spheres: A New Pathway to Nano-Dimensioned Zeolite-Based Catalysts

5 years ago

Densification of Silica Spheres: A New Pathway to Nano-Dimensioned Zeolite-Based Catalysts

Albert Gonche Fortunatus Machoke, Wilhelm Schwieger, Martin Hartmann, Martin Schmiele, Erdman Spiecker, Tobias Unruh, Benjamin Apeleo Zubiri, Rainer Leonhardt, Venkata Ramana Reddy Marthala

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. Silica-rich nanosized zeolites were crystallized by the densification of amorphous, mesoporous silica particles acting as the precursor. Interestingly, during this transformation, the morphology of the precursor was maintained and just the size, phase and porosity changed.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/chem.201702768