Dealumination of hexagonal (EMT)/cubic (FAU) zeolite intergrowth materials: A SEM and HRTEM study
- Iwaki Meisei Univ., Fukushima (Japan)
- Tohoku Univ., Sendai (Japan)
- UMIST, Manchester (United Kingdom)
- Unilever Research, Merseyside (United Kingdom)
The aim of this paper is to describe the effects of mild dealumination of the end members (FAU, EMT) and intergrowths produced using crown ethers on the nature of the resultant zeolite. The end members and intergrowths were prepared as described previously and dealuminated according to the following procedure. The intergrowth was prepared from a mixture of crown ethers; 66% 18-crown-6 and 33% 15-crown-5 to give an ordered intergrowth. The zeolites were first calcined to remove the crown ether template (600{degree}C, flowing air, 16 h) and then exchanged with ammonium ions. The zeolite (6 g) was slurried in ammonium acetate solution (450 cm{sup 3}, 0.8 M), and to this was added slowly 15.6 cm{sup 3} of ammonium hexafluorosilicate solution (0.5 M). The mixture was stirred at 75{degree}C for 3 h. The zeolite was collected and carefully washed with water (3 x 100 cm{sup 3}). The dealuminated samples were characterized by {sup 29}Si and {sup 27}Al MAS NMR, X-ray powder diffraction and adsorption measurements. These data indicate that the resultant materials are highly crystalline and showed no signs of structural degradation both in short-range order ({sup 27}Al, {sup 29}Si MAS NMR) and long-range order (XRD). However, the SEM and high-resolution images were particularly informative.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 39385
- Journal Information:
- Chemistry of Materials, Vol. 6, Issue 12; Other Information: PBD: Dec 1994
- Country of Publication:
- United States
- Language:
- English
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