Multimodal Zr-Silicalite-1 zeolite nanocrystal aggregates with interconnected hierarchically micro-meso-macroporous architecture and enhanced mass transport property

Hierarchical porous architecture with interconnected trimodal micro-meso-macroporous systems constructed from uniform zeolite Zr-doped silicalite-1 nanocrystals has been prepared. The synthesis has been made by using glycerin as a reaction medium via a quasi-solid-state crystallization of hierarchically meso-macroporous zirconosilicate precursor under the effect of the structure directing agent TPAOH. The presence of glycerin is crucial in the synthesis systems to maintain the porous hierarchy. The pores inter-connectivity, Zr location in the framework, the acidity and the catalytic activity have been studied by laser-hyperpolarized 129Xe NMR spectroscopy, UV–visible spectroscopy, temperature-programmed desorption of ammonia and the catalytic isopropylbenzene cracking probe reaction, respectively. The products possess well-defined macrochannels interconnected with mesopores located in the macropore walls, which in turn have been constructed from microporous MFI-type zeolite units. 129Xe NMR study indicated that the hierarchically micro-, meso-, macro-pore systems are homogeneously distributed throughout the final materials and well interconnected, which is important for molecular diffusion. The TPD-NH3 investigation revealed that the hierarchically micro-meso-macroporous materials constructed from zeolite Zr-Silicalite-1 nanocrystals present strong acidity.

Figure optionsDownload high-quality image (175 K)Download as PowerPoint slideHighlights
► Hierarchical porous material with interconnected trimodal micro-meso-macroporous structure.
► Zr-doped silicalite-1 nanocrystals.
► A quasi-solid-state crystallization process.
► A good interconnectivity of micro-meso-macropores system.
► The product MMM-ZrS-1 presents strong acidity.