Abstract
Al-MFI and various kinds of metallosilicates were synthesized hydrothermally under various conditions. When fumed silica was used as the Si source, we could observe a regular variation in the crystal morphology from cubic to planar shape of elongated prism as the Si/Al ratio of the Al-MFI increased. For metallosilicates the reversed variation in morphology was detected with respect to the amount of metal per unit cell. In regard to the crystal symmetry, the transition from orthorhombic to monoclinic phase took place as the Si/Al ratio changed from 63 to 99, whereas all the metallosilicates had orthorhombic phase because of the metal ions present in the non-framework. A careful XRD analysis indicated that the intensity ratio of the 8.8° 2θ peak to the 7.8° 2θ peak was strongly influenced by the morphology. It turned out that, as the peak ratio increased, the morphology tended to change from cubic to planar shape. This leads to the speculation that thep-selectivity might be related to the said peak ratio and this was confirmed by experimental data obtained from toluene alkylation.
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Jung, JH., Lee, JK., Kim, JK. et al. p-Selectivity of the Al-MFI substitutional series in alkylation of toluene. Korean J. Chem. Eng. 17, 461–467 (2000). https://doi.org/10.1007/BF02706861
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DOI: https://doi.org/10.1007/BF02706861