• Journal of the Korean Chemical Society
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• v.32 no.2
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• pp.149-155
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• 1988

Pentasil zeolites, including ZSM-5, ZSM-8, ZSM-11 and silicalites, were synthesized using various organic cations. Synthesis run was carried out in a Parr pressure reactor of $2{\ell}$ capacity and a self-constructed reactor with a magnetic stirring system. The reactant materials used are colloidal silica (Snowtex), sodium aluminate, sodium chloride, TEA, TPA, TBA, Choline and water. The composition of starting materials and the reaction temperature were found to be important factors for the synthesis of uniform pentasil zeolites.

• Journal of the Korean Chemical Society
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• v.51 no.2
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• pp.178-185
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• 2007

Intermediate pentasil borosilicate zeolite-like materials have been crystallized by a novel method named steam-assisted conversion, which involves vapor-phase transport of water. Indeed, amorphous powders obtained by drying Na2O.SiO2.B2O3.TBA2O gels of various compositions using different boron sources are transformed into crystalline borosilicate zeolite belonging to pentasil family structure by contact with vapors of water under hydrothermal conditions. Using a variant of this method, a new material which has an intermediate structure of MFI/MEL in the ratio 90:10 was crystallized. The results show that steam and sufficiently high pH in the reacting hydrous solid are necessary for the crystallization to proceed. Characterization of the products shows some specific structural aspects which may have its unique catalytic properties. X-ray diffraction patterns of these microporous crystalline borosilicates are subjected to investigation, then, it is shown that the product structure has good crystallinity and is interpreted in terms of regular stacking of pentasil layers correlated by inversion centers (MFI structure) but interrupted by faults consisting of mirror-related layers (MEL structure). The products are also characterized by nitrogen adsorption at 77 K that shows higher microporous volume (0.160 cc/g) than that of pure MFI phase (0.119 cc/g). The obtained materials revealed high surface area (~600 m2/g). The infrared spectrum reveals the presence of an absorption band at 900.75 cm-1 indicating the incorporation of boron in tetrahedral sites in the silicate matrix of the crystalline phase.

• Journal of the Korean Chemical Society
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• v.28 no.1
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• pp.62-69
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• 1984

The reaction of toluene with ethanol was studied over various cation-exchanged pentasil zeolite catalysts. The toluene disproportionation reaction to produce xylenes increased with increasing reaction temperature and the activity of alkylation of toluene with ethanol showed maximum at around $400^{\circ}C$. Only Cs-ZSM-5 catalyst showed pronounced p-ethyltoluene selectivity increasing to 96% with increasing degree of Cs-exchange. The sorption rate of m-xylene was lower for Cs-exchanged ZSM-5 than H-ZSM-5 catalyst. These phenomena were interpreted in terms of shape selectivity arising from the partial blocking of channel intersections by large cesium ions.

• Applied Chemistry for Engineering
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• v.4 no.4
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• pp.776-784
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• 1993

A pentasil zeolite, ZSM-5 was synthesized in the absence of organic template, $TPA^+$ ion at $210^{\circ}C$. It was realized that a conventional method can not be applied to the synthesis system where organic templates are not used. The results indicated that the compositional range for the crystallization of ZSM-5 is very narrow, requiring very careful controls in the $Na_2O/SiO_2$and $SiO_2/Al_2O_3$ratios. In addition, the results showed that the effects of mixing method, aging and reaction time on the crystallization of ZSM-5 were extraordinarily significant.