Rapid crystallization method

Figure 5- Conceptional illustration for the change of crystallization rate and crystallinity with time on hydrothermal treatment in the rapid-crystallization method with a programmed temperature rise.

Figure 6. Performance of methanol conversion on ZSM-5 s prepared by the slow and the rapid crystallization methods.

Metallosilicates incorporating catalytically active metal such as V-silicate (l 7) and Cu-silicate (ij ) could also be prepared by the rapid crystallization method. These novel catalytic materials are expected as oxidation catalysts involving shape selective function. 

In conclusion, the rapid crystallization method is very effective not only for rapid synthesis, but also for synthesis of metal-containing uniform zeolitic materials which show higher catalytic activity and selectivity. 

Zinc was introduced in H-ZSM-5 (Si/Al=15, synthesized without template by Chemie AG Bitterfeld) by threefold ion exchange with Zn(N03)2 solution at 353 K (proton exchange degree 75 %, corresponding to 2.4 wt% Zn, denoted as ZnH-[Al]MFI). [Zn]MFI was synthesized according to the rapid crystallization method [11] at Kyoto University (Si/Zn=20, 40 and 100). Protonic MFI was obtained after removal of template at 813 K by ion exchange with NH4NO3 solution at 353 K and subsequent calcination at 813 K. MFI structure was confirmed by X-ray diffraction. 

MFI-type Al- and Ga-silicate catalysts were synthesized by the rapid crystallization method [5], and they were dried at 1205C over night and calcined at 54050 for 3.5 h. The calcined samples were ion-exchanged by IN NH4NO solution twice, and they were calcined to form H-type silicate. 

Application of the rapid crystallization method to syntheses of various metallosilicates. 

Ferrisilicate with MFI structure was synthesized using 1,6-hexanediammine as a template by the rapid crystallization method (ref.13, 16). The details of the synthesis will be published elsewhere. 

Cat. 1 Cu/H-ZSM-5 H-ZSM-5 having Si/Al atomic ratio 40 prepared by the rapid crystallization method (ref. 3) was ion-exchanged by using 0.5 mol aqueous solution of Cu nitrate at room temperature. The Cu loading was 1.00 wt% which corresponded to 80% ion-exchanged. 

Cat. 2 Cu-silicate MFI-type Cu-silicate prepared by the rapid crystallization method. The Cu content was 0.57 wt%. 

Inui, T., and Pu, S B., Separation of 2,6-dimethylnaphthalene from a mixture of its isomers using lithium-incorporated zeolite-Y synthesized by rapid crystallization method. Sep. Technol.. 5(4). 229-238 (1995). 

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