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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References
Argauer, R. J. and Landolt, G. R., US Patent, 3,762,888 (1972).
Cejka, J., Zilkova, N., Wichterlova, B., Edermirth, G. and Lercher, J. A., “Decisive Role of Transport Rate of Products for Zeolite para-Selectivity: Effect of Coke Deposition and External Surface Silylation on Activity and Selectivity of HZSM-5 in Alkylation of Toluene,”Zeolites,17, 265 (1996).
Fang, L. Y., Liu, S. B. and Wang, I., “Enhanced para-Selectivity by Selective Coking during Toluene Disproportionation over H-ZSM-5 Zeolite,”J. Catal.,185, 33 (1999).
Gabelica, Z., Blom, N. and Derouane, E. G., “Synthesis and Characterization of ZSM-5 Type Zeolites-3. A Critical Evaluation of the Role of Alkali and Ammonium Cations,”Appl. Catal.,5, 227 (1983).
Jansen, J. C., Engelen, C.W. R. and van Bekkum, H., “Crystal Growth Regulation and Morphology of Zeolite Single Crystals of the MFI Type,” Zeolite Synthesis, Occelli, M. L. and Robson, H. E., eds., ACS Symp. Ser., Am. Chem. Soc., Washington DC,398, 257 (1989).
Jeong, J. H., “A Study on the Alkylation of Aromatic Compounds over ZSM-5 Type Catalysts,” Ph. D. Thesis, Seoul Nat. Univ., Seoul (1992).
Kim, J. K., “The Morphological Effect of MFI-Zeolite Catalysts on the para-Selectivity in Toluene Alkylation,” M.S. Thesis, Seoul Nat. Univ., Seoul (1994).
Masuda, T., Fujikata, Y., Nishida, T. and Hashimo, K., “The Influence of Acid Sites on Intracrystalline Diffusivities within MFI-Type Zeolites,”Microporous Mater.,23, 157 (1998).
Mirth, G. and Lercher, J. A., “On the Role of Product Isomerization for Shape Selective Toluene Methylation over HZSM5,”J. Catal.,147, 199 (1994).
Nakamoto, H. and Takahashi, H., “Crystal Symmetry Change of ZSM-5 by Various Treatments,”Chem. Lett., 1013 (1981).
Paparatto, G., Moretti, E., Leofanti, G. and Gatti, F., “Toluene Ethylation on ZSM Zeolites,”J. Catal.,105, 227 (1987).
Szostak, R., “Molecular Sieves: Principles of Synthesis and Identification,” Van Nostrand Reinhold, New York (1989).
Triantafillidis, C. S., Evmiridis, N. P., Nalbandian, L. and Vasalos, I. A., “Kinetics, Catalysis, and Reaction Engineering-Performance of ZSM-6 as a Fluid Catalytic Cracking Catalyst Additive: Effect of the Total Number of Acid Sites and Particle Size,”Ind. End. Chem. Res.,38, 916 (1999).
Wu, E. L., Lawton, S. L., Olson, D. H., Rohrman Jr., A. C. and Kokotailo, G. T. J., “ZSM-5 Factors Affecting Crystal Symmetry,”Phys. Chem.,83, 2777 (1979).
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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