A new two-dimensional zeolitic imidazolate framework (named as ZIF-L) was synthesized in zinc salt and 2-methylimidazole (Hmim) aqueous solution at room temperature. ZIF-L (Zn(mim)2·(Hmim)1/2·(H2O)3/2 or C10H16N5O3/2Zn) has unique cushion-shaped cavities leaf-like crystal morphology, exhibits excellent CO2 adsorption properties.

The synthesis of pure silica MWW type zeolite ITQ-1 using trimethyladamantammonium (TMAda+) is described. reproducibility the synthesis, as well quality materials obtained, greatly improved if assisted by hexamethyleneimine (HMI) a second organic additive. As TMAda+ too large to fit into sinusoidal 10 MR channel (i.e., delimited ring tetrahedra), stabilization this seems require presence additional moieties. In absence HMI, these probably come from either partial degradation or organics...

Despite substantial advances in crystal structure determination methodology for polycrystalline materials, some problems have remained intractable. A case point is the zeolite catalyst IM-5, whose has eluded almost 10 years. Here we present a charge-flipping structure-solution algorithm, extended to facilitate combined use of powder diffraction and electron microscopy data. With this elucidated complex with 24 topologically distinct silicon atoms an unusual two-dimensional medium-pore...

Abstract The solid‐state structures of three stereoisomer, 1–3 , the cyclic tetramer 3‐aminobutanoic acid are presented. These cyclo‐β‐peptides were found to be highly insoluble materials, and it proved impossible grow crystals sufficient quality for X‐ray single‐crystal analysis. samples were, however, suitable candidates structure determination from powder diffraction data ( Fig. 1 ), application this method is described. All isomers have been adopt tubular Figs. 2–4 ) in a fashion similar...

The principle of integral metal–organic framework (MOF) reconstruction is demonstrated for differently degraded HKUST‐1 via a facile, one‐step, solvent‐assisted treatment. Controlled MOF degradation by exposure to 77% humidity, liquid water, and diluted hydrochloric acid produces mixture non‐porous crystalline hybrid materials containing protonated linker copper‐oxo species, which are then reconstructed back into high‐quality contacting them with ethanol. X‐ray diffraction sorption kinetics...

The charge-flipping structure-solution algorithm introduced by Oszlányi and Süto in 2004 has been adapted to accommodate powder diffraction data. In particular, a routine for repartitioning the intensities of overlapping reflections implemented within iterative procedure. This is done modifiying electron density map with histogram-matching algorithm, then using Fourier coefficients obtained from this repartition structure factor amplitudes each overlap group. effectiveness demonstrated five...

A new zeolite (SSZ-52, |(C14H28N)6Na6(H2O)18|[Al12Si96O216]), related to the DeNOx catalyst Cu-SSZ-13 (CHA framework type), has been synthesized using an unusual polycyclic quaternary ammonium cation as structure-directing agent. By combining X-ray powder diffraction (XPD), high-resolution transmission electron microscopy (HRTEM) and molecular modeling techniques, its porous aluminosilicate structure (R3m, a = 13.6373(1) Å, c 44.7311(4) Å), which can be viewed 18-layer stacking sequence of...

The structure of the calcined form 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. framework is a polytype MWW can be viewed as disordered ABC-type stacking MWW-layers. HRTEM XRPD simulations show that sequence almost random, with each layer being shifted ±1/3 along ⟨110⟩ direction respect to...

Can the location of organic structure-directing agent (SDA) inside channel system a zeolite be determined experimentally in systematic manner? In an attempt to answer this question, we investigated six borosilicate zeolites known framework structure (SSZ-53, SSZ-55, SSZ-56, SSZ-58, SSZ-59, and SSZ-60), where SDA had only been simulated using molecular modeling techniques previous studies. From synchrotron powder diffraction data, were able retrieve reliable experimental positions for by...

X-ray analysis reveals a zeolite structure in which 10-sided channels are periodically disrupted by 12-sided channels.

The structure of the as-synthesized borosilicate zeolite SSZ-87 has been solved by combining high-resolution X-ray powder diffraction (XPD) and rotation electron (RED) techniques. unit cell space group symmetry were found from XPD data, essential for initial analysis RED data. Although data only 15% complete, this proved to be enough solution with program Focus. framework topology is same as that ITQ-52 (IFW), but locations directing agent (SDA) B atoms could also determined. large cages...

The synthesis of the high-silica zeolite SSZ-61 using a particularly bulky polycyclic structure-directing agent and subsequent elucidation its unusual framework structure with extra-large dumbbell-shaped pore openings are described. By information derived from variety X-ray powder diffraction electron microscopy techniques, complex structure, 20 Si atoms in asymmetric unit, could be determined full refined. at waist dumbbell only three-connected bonded to terminal O pointing into channel....

Separations of small molecules such as CO2 and N2 or CH4 are key to many industrial processes, but it is not always easy find a molecular sieve that can discriminate between these withstand the harsh conditions often required. The high-silica zeolite SSZ-45, which was synthesized using N-cyclopentyldiazabicyclooctane structure directing agent (SDA), found exhibit excellent thermal stability rather unusual adsorption properties under pressure. That is, has potential in area molecule...

Abstract The direct conversion of methane to methanol using oxygen is a challenging but potentially rewarding pathway towards utilizing methane. By stepwise chemical looping approach, copper‐exchanged zeolites can convert methanol, productivity still too low for viable implementation. However, if the nature active site could be elucidated, that information used design more effective catalysts. employing anomalous X‐ray powder diffraction with support from theory and other techniques, we have...

The adsorption and reaction properties of heterogeneous zeolite catalysts (e.g. for catalytic cracking petroleum, partial oxidation natural gas) depend strongly on the types distributions Al heteroatoms in aluminosilicate frameworks. origins these have been challenging to discern, owing part structural complexity zeolites. Herein, combined solid-state NMR synchrotron X-ray powder diffraction analyses show atoms locate preferentially certain framework sites catalyst Al-SSZ-70....

The location of aluminum in a zeolite framework structure defines the accessibility and geometry catalytically active sites, but determining this crystallographically is fraught with difficulties. Typical catalysts contain only small amount aluminum, X-ray scattering factors for silicon are very similar. To address problem, we have exploited properties resonant powder diffraction across Al K edge, where factor changes dramatically. By combining conventional synchrotron data those collected...

A highly crystalline sample of the extra-large-pore, high-silica zeolite UTD-1 has been prepared in fluoride medium. The resulting product (UTD-1F) a powder diffraction pattern remarkably different from that published for calcined form conventionally UTD-1, and it could only be indexed on monoclinic unit cell. crystal structure was determined ab initio space group P21/c synchrotron data collected textured sample. structure, with 69 non-H atoms asymmetric unit, is by far largest solved...