Solid-State NMR Studies of Zeolites

The name zeolite (from the Greek fea = to boil and h9oa = stone) was coined by Cronstedt (28) in 1756 to describe the behavior of the newly discovered mineral stilbite. When heated, stilbite loses water rapidly and thus 

Classification of Zeolites According to Secondary Building Units 

Classifi- cation Zeolite N Free aperture of channels (A) Classifi- cation Zeolite N Free aperture of channels (A) 

The ZSM series (for Zeolite Socony Mobil) of highly siliceous zeolites is prepared from solutions containing alkylammonium bases. 

Other elements, such as Ga and Ge, can substitute for Si and A1 in the zeolitic framework, and there are claims that many other elements can also do so. New classes of nonsilicate zeolite-type crystalline aluminophosphates (31) and silicoaluminophosphates (SAPO) (65) have been reported but relatively little is known about their chemical behaviour. 

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Solid-state NMR studies of zeolites have recently been reviewed (43,44). 

The 29si isotope has a natural abundance of 4.7% and no quadrupole moment (1=1/2). The obtained resonance lines for 31p and 29gi are usually narrow, and due to their important role as framework elements (besides 7a1), these nuclei have been widely used in solid-state NMR studies of zeolitic materials for structural investigations. 

Solid-State NMR Studies of Zeolites and Related Systems... 

Rocha, )., Carr, S.W., and Klinowski,). (1991) A1 quadrupole nutabon and H - A1 cross-polarizabon solid-state NMR studies of ulbastahle zeolite Y with fast magic-angle spinning. Chem. Phys Lett., 187, 401-408. 

H, 2H and 29Si solid state NMR study of guest acetone molecules occupying the zeolitic channels of partially dehydrated sepiolite clay... 

H, 2H and 29Si Solid State NMR Study of Guest Acetone Molecules Occupying the 551 Zeolitic Channels of Partially Dehydrated Sepiolite Clay M.R. Weir, G.A. Facey and C. Detellier... 

Nanociystalline zeolites (ciystal sizes of less than 100 nm) are porous aluminosilicate nanomaterials with increased surface areas relative to conventional micron-sized zeolites. Nanocrystalline zeolites are potentially useful for CWA decontamination applications because of their enhanced absorptive and catalytic properties. This chapter describes FTIR and solid state NMR studies of the thermal reactivity of two CWA simulants, 2-CEES (2 chloroethyl sulfide) and DMMP (dimethylmethylphosphonate) on nanocrystalline zeohtes, such as NaZSM-5 (sihcalite, purely siliceous form of ZSM-5) and NaY, with crystal sizes of approximately 25 nm. 

D. Freude, J. Klinowski, and H. Hamdan, Chem. Phys. Lett., 149, 355 (1988). Solid-State NMR Studies of the Geometry of Bronsted Acid Sites in Zeolitic Catalysts. 

FIGURE 2.97 H MAS NMR spectra of zeolites calcined at 433 K and dealnminated HY calcined at 673 K, rotor frequency was 10 kHz for 73LaNaY and 3 kHz for others. (Adapted from Solid State Nuclear Magn. Reson., 6, Hunger, M., Multinuclear solid-state NMR studies of acidic and non-acidic hydroxyl protons in zeolites, 1-29,1996, Copyright 1996, with permission from Elsevier.)... 

The solid state NMR study of the Beckmann rearrangement catalyzed by MFI-type zeolites with different acid catalysts disclose that the conversion of cyclohexanone oxime to caprolactam is catalyzed by SiOH, SiOH[Bl and SiOHAl groups as in silicate-I, zeolites H-[B]ZSM-5 and H-ZSM-5. ... 

Earl, W.L., Fritz, P.O., Gibson, A.A.V., and Lunsford, J.H. A solid-state NMR study of acid sites in zeolite Y using ammonia and trimethylamine as probe molecules, y. Phys. Chem. 1987, 91, 2091-2095. 

Eckman RR, Vega AJ. Deuterium solid-state NMR study of the dynamics of molecules sorbed by zeolites. J Phys Chem 1986 90 4679-83. 

Hunger M. Multinuclear solid-state NMR studies of acidic and non-acidic hydroxyl protons in zeolites. 

Anderson MW, Klinowski J. Solid-state NMR studies of the shape-selective catalytic conversion of methanol into gasoline on zeolite ZSM-5. J Am Chem Soc 1990 112 10-6. 

M. Hunger, D. Freude, D. Fenzke, H. Pfeifer etal., H solid-state NMR studies of the geometry of Bronsted acid sites in zeolites H-ZSM-5. Chem. Phys. Lett. 191,391-395 (1992)... 

ST1 is a very favorable nucleus for solid-state NMR studies it has f = 2, high natural abundance and high sensitivity. Its large chemical shift range makes it possible to observe individual environments of the nucleus. Thallium can be easily introduced into zeolites by cation exchange. 

Bourbigot, S., Le Bras, M., Delobel, R., Decressain, R., and Amoureux, J.P. 1996. Synergistic effect of zeolite in an intumescence process Study of the carbonaceous structures using solid-state NMR. Journal of the Chemical Society—Faraday Transactions 92(18) 3435-3444. 

Zeolite samples were placed in 5mm O.D. tubes for solid state NMR studies and in 4mm O.D. tube for studies with a liquid state spectrometer. The amount of... 

Over the past decades, considerable effort has been focussed on the evaluation of the various parameters that influence zeolite crystallization. (3j 4) More recently, spectroscopic techniques are being used to monitor zeolite growth. These studies include high resolution NMR spectroscopy of silicate and aluminate solutions.(5.6) solid state NMR spectroscopy of the amorphous phase(7.8) and Raman spectroscopic studies of solution and solid phases during crystallization.(9-141 The typical solutions present during zeolite growth contain various oligomeric silicate species, A1(0H)4 and minute amounts of aluminosilicate anions, because of... 

However, todays high-resolution solid-state NMR equipment allow the study of solids in a routine manner and provide information of analytical quality, mainly due to the above mentioned improvements. As already mentioned, a large number of review papers and bodts exist, covering the enormous literature available within the field of solid-state NMR related to zeolitic materials. Therefore, a certain number is listed among the references (1,3-16), and I would like to advice the interested reader to consult those reviews for an extensive survey, since this paper will focus mainly on the highlights of recent developments. 

This chapter does not cover the most common aspects of the solid-state NMR techniques employed in the study of heterogeneous catalysts such techniques are described in Chapter 4. Since this chapter emphasizes the surface characterization of silica and alumina systems and silica aluminas by NMR methods, only those technical aspects highly relevant to surface characterization and not otherwise emphasized in this volume are explicitly discussed here. NMR studies of zeolites and clays are treated in separate chapters, and the bulk structures of silica and alumina systems are covered by Eckert. Unavoidably this chapter is also concerned with dynamics at the surface, although the amount of detailed work on that subject to date is limited. With the increasing availability of variable-temperature solid-state NMR equipment, however, one can expect that attention devoted to dynamics at surfaces will increase markedly during the next few years. 

P-19 - Solid state MAS NMR studies of zeolites and alumina reacted with chlorofluorocarbons (CCI2F2, CHCIF2)... 

NMR studies of metals in sohd state non-metallic materials such as zeolites, inorganic complexes, glasses, coals, polymers, metalloproteins, and RNA have been reviewed. The role of solid state NMR spectroscopy in investigating the structural and functional aspects of these materials with no long range order is evaluated. This overview presents several developments of solid state NMR to the study of a variety of metal containing materials. In particular, the use of the quadrupolar Carr-Purcell-Meiboom-Gill pulse sequence for the acquisition of solid state NMR spectra of quadrupolar nuclei with low natural abundances and low NMR frequencies, and applications of solid state Cd NMR are covered in detail. 

Solid state NMR studies, particularly of silicon and aluminium, occupy a special place in the history of zeolite science, partly because the method was developed and became widely available in the 1970s and 1980s - at the same time as there was an upsurge of industrial and academic interest in these solids. 

Recent, elegant solid-state NMR studies[l] have shown that 29 product molecules are formed in the channels and intersections of the 10-ring, high silica, zeolite ZSM-5 in the methanol to gasolene reaction. Many of these products never escape to the gas phase, either due to extremely small, virtually zero diffusion coefficients or to small diffusion coefficients which result in the molecules being involved in secondary, catalysed reactions during their time of transport from the initial site of reaction to the external surface of the zeolite crystal. 

FIGURE 2.96 H MAS NMR spectra of microsized (solid lines) and nanosized (dashed lines) HZSM-5 zeolites initial and after hydrothermal treatment at different temperatures. (Adapted from Micropor. Mesopor. Mater., 50, Zhang, W., Han, X., Liu, X., and Bao, X., The stability of nanosized HZSM-5 zeolite A high-resolution solid-state NMR study, 13-23, 2001, Copyright 2001, with permission from Elsevier.)... 

Zhang, W., Han, X., Liu, X., and Bao, X. 2001. The stability of nanosized HZSM-5 zeolite A high-resolution solid-state NMR study. Micropor. Mesopor. Mater. 50 13-23. 

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