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The high-silica zeolite SSZ-27 was synthesized using one of the isomers of the organic structure-directing agent that is known to produce the large-pore zeolite SSZ-26 (CON). The structure of the as-synthesized form was solved using multi-crystal electron diffraction data. Data were collected on eighteen crystals, and to obtain a high-quality and complete data set for structure refinement, hierarchical cluster analysis was employed to select the data sets most suitable for merging. The framework structure of SSZ-27 can be described as a combination of two types of cavities, one of which is shaped like a heart. The cavities are connected through shared 8-ring windows to create straight channels that are linked together in pairs to form a one-dimensional channel system. Once the framework structure was known, molecular modelling was used to find the best fitting isomer, and this, in turn, was isolated to improve the synthesis conditions for SSZ-27.

The high-silica zeolite SSZ-27 was synthesized using one of the isomers of the organic structure-directing agent that is known to produce the large-pore zeolite SSZ-26 (CON). The structure of the as-synthesized form was solved using multi-crystal electron diffraction data. Data were collected on eighteen crystals, and to obtain a high-quality and complete data set for structure refinement, hierarchical cluster analysis was employed to select the data sets most suitable for merging. The framework structure of SSZ-27 can be described as a combination of two types of cavities, one of which is shaped like a heart. The cavities are connected through shared 8-ring windows to create straight channels that are linked together in pairs to form a one-dimensional channel system. Once the framework structure was known, molecular modelling was used to find the best fitting isomer, and this, in turn, was isolated to improve the synthesis conditions for SSZ-27., BN/Arjen Jakobi Lab

The high-silica zeolite SSZ-27 was synthesized using one of the isomers of the organic structure-directing agent that is known to produce the large-pore zeolite SSZ-26 (CON). The structure of the as-synthesized form was solved using multi-crystal electron diffraction data. Data were collected on eighteen crystals, and to obtain a high-quality and complete data set for structure refinement, hierarchical cluster analysis was employed to select the data sets most suitable for merging. The framework structure of SSZ-27 can be described as a combination of two types of cavities, one of which is shaped like a heart. The cavities are connected through shared 8-ring windows to create straight channels that are linked together in pairs to form a one-dimensional channel system. Once the framework structure was known, molecular modelling was used to find the best fitting isomer, and this, in turn, was isolated to improve the synthesis conditions for SSZ-27., BN/Arjen Jakobi Lab

Zeolites are crystalline aluminosilicate framework materials with corner sharing TO4 (T = Al, Si) tetrahedra forming well-defined pores and channels. Many zeolites are built from similar building units (i.e., isolated units, chains or layers), which are connected in different ways to form a variety of topologies. We have identified ten zeolite frameworks that share the same two-dimensional "butterfly” net containing 5-, 6- and 10-rings: *MRE, FER, MEL, SZR, MFS, MFI, TUN, IMF, BOG and TON. Different orientations of the TO4 tetrahedra within the layer lead to different connectivities between neighboring layers. Some layers are corrugated and some are flat, resulting in different channel systems parallel to the layer. We found some interesting relationships between the unit cell parameters and this channel system that allow the size of the channels and their directions to be deduced from the unit cell dimensions. This may facilitate the prediction of new members of this zeolite family. In addition, other zeolites containing the "butterfly” layers are also discussed.

A new medium-pore germanosilicate, denoted IM-18, with a three-dimensional 8 x 8 x 10-ring channel system, has been prepared hydrothermally using 4-dimethylaminopyridine as an organic structure-directing agent (OSDA). Due to the presence of stacking disorder, the structure elucidation of IM-18 was challenging, and a combination of different techniques, including electron diffraction, high-resolution transmission electron microscopy (HRTEM), and Rietveld refinement using synchrotron powder diffraction data, was necessary to elucidate the details of the structure and to understand the nature of the disorder. Rotation electron diffraction data were used to determine the average structure of IM-18, HRTEM images to characterize the stacking disorder, and Rietveld refinement to locate the Ge in the framework and the OSDA occluded in the channels.

In this chapter, we delve into the X-ray diffraction techniques that can be used to address the question as to where the organic structure-directing agents (OSDAs) are located in the pores of a zeolite framework structure and give an overview of some of the practical issues involved. By examining the results of such investigations, we attempt to establish whether the OSDAs are really disordered, as is often claimed, or if it is the methods we use that give this impression. In fact, the non-framework species in the channels of a zeolite appear to be arranged quite logically in a chemically sensible manner. In most cases, the OSDA within the pores can be described well as a superposition of just a few discrete, symmetryrelated positions, provided the discrepancies between the OSDA and framework symmetries can be resolved. On the basis of some selected examples, we show that their arrangements can be extracted from experimental data using a systematic strategy and sometimes supplementary information.

The structure of the calcined form of the high-silica zeolite SSZ-70 has been elucidated by combining synchrotron X-ray powder diffraction (XRPD), high-resolution transmission electron microscopy (HRTEM), and two-dimensional (2D) dynamic nuclear polarization (DNP)-enhanced NMR techniques. The framework structure of SSZ-70 is a polytype of MWW and can be viewed as a disordered ABC-type stacking of MWW-layers. HRTEM and XRPD simulations show that the stacking sequence is almost random, with each layer being shifted by +/- 1/3 along the < 110 > direction with respect to the previous one. However, a small preponderance of ABAB stacking could be discerned. DNP-enhanced 2D Si-29{Si-29} J-mediated NMR analyses of calcined Si-SSZ-70 at natural Si-29 isotopic abundance (4.7%) establish the through-covalent-bond Si-29-O-Si-29 connectivities of distinct Si sites in the framework. The DNP-NMR results corroborate the presence of MWW layers and, more importantly, identify two distinct types of Q(3) silanol species at the surfaces of the interlayer regions. In the first, an isolated silanol group protrudes into the interlayer space pointing toward the pocket in the adjacent layer. In the second, the surrounding topology is the same, but the isolated -SiOH group is missing, leaving a nest of three Si-O-H groups in place of the three Si-O-Si linkages. The analyses clarify the structure of this complicated material, including features that do not exhibit long-range order. With these insights, the novel catalytic behavior of SSZ-70 can be better understood and opportunities for enhancement recognized.

The structure of the complex zeolite IM-5 (Cmcm, a = 14.33(4) Å, b = 56.9(2) Å, c = 20.32(7) Å) was determined by combining selected area electron diffraction (SAED), 3D reconstruction of high resolution transmission electron microscopy (HRTEM) images from different zone axes and distance least squares (DLS) refinement. The unit cell parameters were determined from SAED. The space group was determined from extinctions in the SAED patterns and projection symmetries of HRTEM images. Using the structure factor amplitudes and phases of 144 independent reflections obtained from HRTEM images along the [100], [010] and [001] directions, a 3D electrostatic potential map was calculated by inverse Fourier transformation. From this 3D potential map, all 24 unique Si positions could be determined. Oxygen atoms were added between each Si-Si pair and further refined together with the Si positions by distance-least-squares. The final structure model deviates on average 0.16 Å for Si and 0.31 Å for O from the structure refined using X-ray powder diffraction data. This method is general and offers a new possibility for determining the structures of zeolites and other materials with complex structures

Electron microscopy techniques yield information for crystal structure analysis that is remarkably complementary to that obtained from X-ray powder diffraction data. Structures of polycrystalline materials that resist solution by either method alone can sometimes be solved by combining the two. For example, the intensities extracted from an X-ray powder diffraction pattern are kinematical and can be interpreted easily, while those obtained from a typical selected area electron diffraction (SAED) or precession electron diffraction (PED) pattern are at least partially dynamical and therefore more difficult to use directly. On the other hand, many reflections in a powder diffraction pattern overlap and only the sum of their intensities can be measured, while those in an electron diffraction pattern are from a single crystal and therefore well separated in space. Although the intensities obtained from either SAED or PED data are less reliable than those obtained with X-rays, they can be used to advantage to improve the initial partitioning of the intensities of overlapping reflections. However, it is the partial crystallographic phase information that can be extracted either from high-resolution transmission electron microscopy (HRTEM) images or from PED data that has proven to be particularly useful in combination with high-resolution X-ray powder diffraction data. The dual-space (reciprocal and real space) structure determination programs Focus and Superflip have been shown to be especially useful for combining the two different types of data

The vertical bar Na10.2KCs0.8(8)[Al12Si12O48](8)(Fm3c)-LTA zeolite adsorbs CO2-over-CH4 with a high selectivity (over 1500). The uptake of carbon dioxide is also high (3.31 mmol g(-1), 293 K, 101 kPa). This form of zeolite A is a very promising adsorbent for applications such as biogas upgrading, where keeping the adsorption of methane to a minimum is crucial.

The synthesis of the germanosilicate CIT-13, a molecular sieve that is the first to have a two-dimensional (2D) pore system possessing pores that are bounded by 14- and 10-rings, is accomplished using a family of monoquaternary, benzyl-imidazolium organic structure-directing agents (OSDAs) in aqueous media containing fluoride. CIT-13 is prepared using either hydrogen fluoride (HF) or ammonium fluoride (NH4F). The structure refinement suggests that most of the Ge atoms are located in the d4r(double-4-rings) units, and that there are framework disorders in the arrangement of those d4r units. Other characterizations of CIT-13 such as Si-29 MAS NMR spectra, Ar-adsorption isotherms, and so forth are presented and compared to those of IM-12 (UTL), a previously reported germanosilicate with 14- and 12-ring pores.

The vertical bar Na10.2KCs0.8 vertical bar(8)[Al12Si12O48](8)(Fm3c)-LTA zeolite adsorbs CO2-over-CH4 with a high selectivity (over 1500). The uptake of carbon dioxide is also high (3.31 mmol g(-1), 293 K, 101 kPa). This form of zeolite A is a very promising adsorbent for applications such as biogas upgrading, where keeping the adsorption of methane to a minimum is crucial.

New opportunities for studying (sub)microcrystalline materials with small unit cells, both organic and inorganic, will open up when the X-ray free electron laser (XFEL) presently being constructed in Switzerland (SwissFEL) comes online in 2017. Our synchrotron-based experiments mimicking the 4%-energy-bandpass mode of the SwissFEL beam show that it will be possible to record a diffraction pattern of up to 10 randomly oriented crystals in a single snapshot, to index the resulting reflections, and to extract their intensities reliably. The crystals are destroyed with each XFEL pulse, but by combining snapshots from several sets of crystals, a complete set of data can be assembled, and crystal structures of materials that are difficult to analyze otherwise will become accessible. Even with a single shot, at least a partial analysis of the crystal structure will be possible, and with 10-50 femtosecond pulses, this offers tantalizing possibilities for time-resolved studies.

Zeolites are crystalline aluminosilicate framework materials with corner sharing TO 4 (T = Al, Si) tetrahedra forming well-defined pores and channels. Many zeolites are built from similar building units (i.e., isolated units, chains or layers), which are connected in different ways to form a variety of topologies. We have identified ten zeolite frameworks that share the same two-dimensional butterfly net containing 5-, 6- and 10-rings: (MRE)-M-star, FER, MEL, SZR, MFS, MFI, TUN, IMF, BOG and TON. Different orientations of the TO4 tetrahedra within the layer lead to different connectivities between neighboring layers. Some layers are corrugated and some are flat, resulting in different channel systems parallel to the layer. We found some interesting relationships between the unit cell parameters and this channel system that allow the size of the channels and their directions to be deduced from the unit cell dimensions. This may facilitate the prediction of new members of this zeolite family. In addition, other zeolites containing the butterfly layers are also discussed.

New opportunities for studying (sub)microcrystalline materials with small unit cells, both organic and inorganic, will open up when the X-ray free electron laser (XFEL) presently being constructed in Switzerland (SwissFEL) comes online in 2017. Our synchrotron-based experiments mimicking the 4%-energy-bandpass mode of the SwissFEL beam show that it will be possible to record a diffraction pattern of up to 10 randomly oriented crystals in a single snapshot, to index the resulting reflections, and to extract their intensities reliably. The crystals are destroyed with each XFEL pulse, but by combining snapshots from several sets of crystals, a complete set of data can be assembled, and crystal structures of materials that are difficult to analyze otherwise will become accessible. Even with a single shot, at least a partial analysis of the crystal structure will be possible, and with 10-50 femtosecond pulses, this offers tantalizing possibilities for time-resolved studies.

The synthesis of the high-silica zeolite SSZ-61 using a particularly bulky polycyclic structure-directing agent and the subsequent elucidation of its unusual framework structure with extra-large dumbbell-shaped pore openings are described. By using information derived from a variety of X-ray powder diffraction and electron microscopy techniques, the complex framework structure, with 20 Si atoms in the asymmetric unit, could be determined and the full structure refined. The Si atoms at the waist of the dumbbell are only three-connected and are bonded to terminal O atoms pointing into the channel. Unlike the six previously reported extra-large-pore zeolites, SSZ-61 contains no heteroatoms in the framework and can be calcined easily. This, coupled with the possibility of inserting a catalytically active center in the channel between the terminal O atoms in place of H+, afford SSZ-61 intriguing potential for catalytic applications., AuthorCount:7

The crystal structure of a novel open-framework gallogermanate, SU-66 {|(C6H18N2)(18)(H2O)(32)|[Ga4.8Ge87.2O208]}, has been solved from laboratory X-ray powder diffraction (XPD) data by using a direct-space structure solution algorithm and local structural information obtained from infrared (IR) spectroscopy. IR studies on 18 known germanates revealed that the bands in their IR spectra were characteristic of the different composite building units (CBUs) present in the structures. By comparing the bands corresponding to Ge-O vibrations in the IR spectra of SU-66 with those of the 18 known structures with different CBUs, the CBU of SU-66 could be identified empirically as the Ge-10(O,OH)(27) cluster (Ge-10). The unit cell and space group (extinction symbol P--a; a = 14.963, b = 31.593, c = 18.759 angstrom) were determined initially from the XPD pattern and then confirmed by selected-area electron diffraction. The structure of SU-66 was solved from the XPD data using parallel tempering as implemented in FOX [Favre-Nicolin & Cerny (2002). J. Appl. Cryst. 35, 734-743] by assuming P2(1)ma symmetry and two Ge-10 clusters in the asymmetric unit. Rietveld refinement of the resulting structure using synchrotron XPD data showed the framework structure to be correct and the space group to be Pmma. The framework has extra-large (26-ring) onedimensional channels and a very low framework density of 10.1 Ge/Ga atoms per 1000 angstrom(3). SU-66, with 55 framework atoms in the asymmetric unit, is one of the more complicated framework structures solved from XPD data. Indeed, 98% of the reflections were overlapping in the XPD pattern used for structure solution. Tests on other open-framework germanates (SU-62, SU-65, SU-74, PKU-12 and ITQ-37) for which the XPD data, unit cell, space group and IR spectra were available proved to be equally successful. In a more complex case (SU-72) the combination of FOX and powder charge flipping was required for structure solution., AuthorCount:6

A new zeolite (SSZ-52, vertical bar(C14H28N)(6)Na-6(H2O)(18)vertical bar[Al12Si96O216]), related to the DeNOx catalyst Cu-SSZ-13 (CHA framework type), has been synthesized using an unusual polycyclic quaternary ammonium cation as the structure-directing agent. By combining X-ray powder diffraction (XPD), high-resolution transmission electron microscopy (HRTEM) and molecular modeling techniques, its porous aluminosilicate framework structure (R (3) over barm, a = 13.6373(1) angstrom, c = 44.7311(4) angstrom), which can be viewed as an 18-layer stacking sequence of hexagonally arranged (Si,Al)(6)O-6 rings (6-rings), has been elucidated. The structure has a three-dimensional 8-ring channel system and is a member of the ABC-6 family of zeolites (those that can be described in terms of 6-ring stacking sequences) like SSZ-13, but it has cavities that are twice as large. The code SFW has been assigned to this new framework type. The large cavities contain pairs of the bulky organic cations. HRTEM and XPD simulations show that stacking faults do occur, but only at the 5-10% level. SSZ-52 has considerable potential as a catalyst in the areas of gas conversion and sequestration., AuthorCount:6

Analysis of the structure of the zeolite ferrierite (framework type FER) synthesized using a combination of tetramethylammonium (TMA) and pyrrolidine as organic structure-directing agents (|((CH3)4N) 0.4((CH2)4NH)3.6H 1.7|[Si33.9Al2.1O72]) has revealed that TMA ions reside exclusively in the [58668 2] cavities of the FER framework, whereas pyrrolidine species are found in both the [586682] cavities and the main 10-ring channel. A similar, but not identical, arrangement of pyrrolidine molecules was found for a sample synthesized with pyrrolidine as the only SDA (|((CH2)4NH)4.2H2.2|[Si 33.8Al2.2O72])). A comparison of the two structures shows the influence of TMA on the location of pyrrolidine and the framework Al. Pyrrolidine species establish stronger interactions with the zeolitic framework than does TMA, suggesting a different ability of the amine to exert an influence on the aluminum distribution of the zeolite. These findings have implications in the catalytic performance of the samples. © 2013 American Chemical Society.

The structure of the complex zeolite IM-5 (Cmcm, a = 14.33(4) angstrom. b = 56.9(2) angstrom, c = 20.32(7) angstrom) was determined by combining selected area electron diffraction (SAED), 3D reconstruction of high resolution transmission electron microscopy (HRTEM) images from different zone axes and distance least squares (DLS) refinement. The unit cell parameters were determined from SAED. The space group was determined from extinctions in the SAED patterns and projection symmetries of HRTEM images. Using the structure factor amplitudes and phases of 144 independent reflections obtained from HRTEM images along the [100], [010] and [001] directions, a 3D electrostatic potential map was calculated by inverse Fourier transformation. From this 3D potential map, all 24 unique Si positions could be determined. Oxygen atoms were added between each Si-Si pair and further refined together with the Si positions by distance-least-squares. The final structure model deviates on average 0.16 angstrom for Si and 0.31 angstrom for O from the structure refined using X-ray powder diffraction data. This method is general and offers a new possibility for determining the structures of zeolites and other materials with complex structures., authorCount :7

Many zeolite structures have remained unsolved for a long time because of their structural complexity, the size of the crystallites or the presence of defects or impurities. By combining electron microscopy and X-ray powder diffraction data, some of them have been solved (e.g. the high-silica zeolite IM-5, which was first reported in 1998 [1] and recently solved using a charge-flipping structure solution algorithm [2] ), while for other zeolites, good X-ray powder diffraction data are hard to obtain (e.g. polymorph A or B of zeolite Beta). Here we demonstrate a complete structure determination of IM-5 (one of the most complicated zeolited) and polymorph B of zeolite Beta [3] using electron crystallography alone. This shows the power and advantage of structure determination by electron microscopy compared with the X-ray diffraction techniques. The method is general and can be applied to both zeolites and other materials, where the crystals are too small or the structure too complicated to be solved from X-ray powder diffraction data alone [4] . It is particularly useful for structures containing defects.

Zeolites are crystalline aluminosilicate framework materials with corner sharing TO4 (T = Al, Si) tetrahedra forming well-defined pores and channels. Many zeolites are built from similar building units (i.e., isolated units, chains or layers), which are connected in different ways to form a variety of topologies. We have identified ten zeolite frameworks that share the same two-dimensional "butterfly” net containing 5-, 6- and 10-rings: *MRE, FER, MEL, SZR, MFS, MFI, TUN, IMF, BOG and TON. Different orientations of the TO4 tetrahedra within the layer lead to different connectivities between neighboring layers. Some layers are corrugated and some are flat, resulting in different channel systems parallel to the layer. We found some interesting relationships between the unit cell parameters and this channel system that allow the size of the channels and their directions to be deduced from the unit cell dimensions. This may facilitate the prediction of new members of this zeolite family. In addition, other zeolites containing the "butterfly” layers are also discussed.

The structure of the complex zeolite IM-5 (Cmcm, a = 14.33(4) Å, b = 56.9(2) Å, c = 20.32(7) Å) was determined by combining selected area electron diffraction (SAED), 3D reconstruction of high resolution transmission electron microscopy (HRTEM) images from different zone axes and distance least squares (DLS) refinement. The unit cell parameters were determined from SAED. The space group was determined from extinctions in the SAED patterns and projection symmetries of HRTEM images. Using the structure factor amplitudes and phases of 144 independent reflections obtained from HRTEM images along the [100], [010] and [001] directions, a 3D electrostatic potential map was calculated by inverse Fourier transformation. From this 3D potential map, all 24 unique Si positions could be determined. Oxygen atoms were added between each Si-Si pair and further refined together with the Si positions by distance-least-squares. The final structure model deviates on average 0.16 Å for Si and 0.31 Å for O from the structure refined using X-ray powder diffraction data. This method is general and offers a new possibility for determining the structures of zeolites and other materials with complex structures

Electron microscopy techniques yield information for crystal structure analysis that is remarkably complementary to that obtained from X-ray powder diffraction data. Structures of polycrystalline materials that resist solution by either method alone can sometimes be solved by combining the two. For example, the intensities extracted from an X-ray powder diffraction pattern are kinematical and can be interpreted easily, while those obtained from a typical selected area electron diffraction (SAED) or precession electron diffraction (PED) pattern are at least partially dynamical and therefore more difficult to use directly. On the other hand, many reflections in a powder diffraction pattern overlap and only the sum of their intensities can be measured, while those in an electron diffraction pattern are from a single crystal and therefore well separated in space. Although the intensities obtained from either SAED or PED data are less reliable than those obtained with X-rays, they can be used to advantage to improve the initial partitioning of the intensities of overlapping reflections. However, it is the partial crystallographic phase information that can be extracted either from high-resolution transmission electron microscopy (HRTEM) images or from PED data that has proven to be particularly useful in combination with high-resolution X-ray powder diffraction data. The dual-space (reciprocal and real space) structure determination programs Focus and Superflip have been shown to be especially useful for combining the two different types of data