A comparative study of hierarchically micro-meso-macroporous solid-acid catalysts constructed by zeolites nanocrystals synthesized via a quasi-solid-state crystallization process

The design, preparation and application of novel hierarchically interconnected micro-meso-macroporous solid-acid catalysts constructed from zeolite nanocrystals via a chemically crystallization process in a quasi solid state system using glycerin medium have been described. These hierarchical solid-acid catalysts possess well-defined macrochannels and interconnected mesopores in the walls which have been constructed from various zeolite microporous units including Zr-silicalite-1, ZSM-5 and Beta nanocrystals, respectively. Meanwhile, the hierarchically micro-, meso-, macro-pore systems are homogeneously distributed throughout the final catalysts. The quasi solid state chemically crystallization processes to generate hierarchical solid-acid catalysts have been investigated in detail. Different hierarchical solid-acid catalysts with microporous MFI or Beta architectures can be obtained by varying crystallization conditions. The resultant hierarchically micro-meso-macroporous solid-acid catalysts show strong acidities and superior catalytic properties for esterification reaction of high free fatty acid (FFA) oils. The hierarchical zeolitic materials with micro-meso-macroporous structure should be advantageous candidates for the application in solid-acid catalysis.