engleski

The Influence Of Gel Properties On The Kinetics Of Crystallization And Particulate Properties Of MFI-Type Zeolites. I. The Influence Of Time And Temperature Of Gel Ageing On The Particulate Properties Of Silicalite-1 Microcrystals

The influence of time and temperature of ageing of the amorphous gel precursor (2.5 Na2O-8TPABr-60SiO2-800H2O) on the particulate properties (particle size distribution, particle shape, number of particles) of silicalite-1 synthesized at 170 deg. C were studied by different experimental methods such as X-ray diffractometry (XRD), differental thermogravimetric analysis (TGA), particle size analysis, FT-infra-red spectroscopy and scanning electron microscopy (SEM). In spite of negligible changes in the crystal morphology, agening of the gel considerably affects the number and size of silicalite-1 crystals in the crystalline end products. The observed effects were discussed in terms of the formation of specific ordered subunits between silicate species and TPA+ ions (germ nuclei) and their role in the nucleation and crystal growth of silicalite-1 crystalls.

crystallization; gel ageing; morphology; nucleation; particulate properties; silicalite-1

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