Preparation and characterization of acidic properties of MCM-41
- Texas A & M Univ., College Station, TX (United States); and others
Mesoporous molecular sieves designated as MCM-41 have been synthesized using the starting reaction gel composition 1SiO{sub 2} - x Al{sub 2}O{sub 3} - 0.11 Na{sub 2}O - 0.23 CTMACl - 0.09 TMAOH- 125 H{sub 2}O. The Si/Al ratio was varied by changing the amount of x from 0 to 0.5. The synthesized samples were characterized by X-ray powder diffraction, thermogravimetric analysis, {sup 29}Si and {sup 27}Al MAS NMR, N{sub 2} sorption and chemical analysis. The results indicated that using fumed silica and sodium aluminate as the sources of silica and aluminum respectively, the MCM-41 can be prepared with a Si/Al ratio as low as 2 without observing the presence of octahedral aluminum. At a Si/Al ratio of 1 the reaction mixture produced a faujasite type material. The acidic properties were examined by FTIR and Nls X-ray photoelectron spectra of chemisorbed pyridine and catalytic properties by the n-hexane Cracking reaction. Both, FTIR and XPS studies indicated that the MCM-41 materials contain Bronsted as well as Lewis acid sites. The n-hexane cracking activity data indicated that MCM-41 materials are less active than ZSM-5 and Beta zeolites for this reaction. These result were discussed in terms of a variety of NMR measurements.
- OSTI ID:
- 126748
- Report Number(s):
- CONF-950402--
- Country of Publication:
- United States
- Language:
- English
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