We directly synthesized one-dimensional zeolite UZM-55 as an aluminosilicate and catalyzed MTH to understand pore structure influence on catalytic properties.

The charge density mismatch concept was applied to the synthesis of high-charge-density silicoaluminophosphate SAPO-69 (OFF) and SAPO-79 (ERI) and zincoaluminophosphate PST-16 (CGS), PST-17 (BPH), PST-19 (SBS), and ZnAPO-88 (MER) molecular sieves. Combined alkali-organoammonium structure direction in these systems is thus enabled. Structure direction is treated from the perspective of stabilizing an ionic framework, the relationships between reaction charge density (OH-/H3PO4), alkali and organoammonium content, and ionicity of tetrahedral framework atoms in successful structure direction are presented.

Zeolites are porous aluminosilicate materials utilized in a variety of sorption, separation, and catalytic applications. The oil refining industry in particular has seen a number of significant advances due to the introduction of new technologies enabled by new zeolites. Of particular importance are zeolites with 10- or 12-membered ring pores, resulting in pore shapes and sizes appropriate for the interaction with small hydrocarbon molecules. Here, the synthesis of a new zeolite UZM-55 is reported and the idealized structure thereof is presented. The most complex structure solved to date, UZM-55 possesses a large triclinic unit cell containing 52 T-sites. The material uniquely contains both 10- and 12-membered ring pores in a single, undulating one-dimensional channel, the first example in a zeolitic material of multiple delimiting rings in a single channel. This discovery opens new opportunities in shape-selective adsorption and catalysis. Demonstrated here is the unique adsorption behavior of UZM-55, shown both experimentally and computationally to adsorb one nonane molecule per unit cell in a linear conformation.

The characterization of coke on spent catalysts is key to understanding deactivation mechanisms in hydrocarbon transformations. In this paper we report the comprehensive characterization (using laser Raman spectroscopy, 13C MAS NMR, temperature-programmed oxidation, XPS, and carbon K-edge NEXAFS) of coke on a series of spent Pt-Re re-forming catalysts as a function of time on stream and position in the catalytic bed. Laser Raman spectroscopy is shown to be rather insensitive to the carbon species present, while 13C MAS NMR finds that the carbon is present primarily as aromatic carbon. The TPO data are consistent with the coke being present on the alumina support and not to a large extent covering the metallic Pt-Re nanoclusters, but the data do suggest the presence of more than one type of coke present. The carbon K-edge NEXAFS data, however, clearly differentiate the types of coke species present. In the more coked samples the features ascribed to graphite become more pronounced, together with an increas...

•Phosphate treatments of MTW/Al2O3 increased selectivity to gasoline up to 97%.•H3PO4 caused conversion of the γ-Al2O3 binding matrix to crystalline tridymite-AlPO4.•Interaction of P with zeolite framework Al species observed, confirming Si-O-Al-O-P bonds.•Si-O-Al-O-P bond formation is a major effect from phosphate treatment.•10%P from H3PO4 on 80/20 MTW/Al2O3 as effective as SPA in oligomerization to gasoline.

Using multiple H-1 and C-13 NMR spectroscopic techniques, we have investigated the C8 cut from samples of liquid products obtained by the oligomerization of light olefins over solid phosphoric acid (SPA) and MTW zeolite. The carbon species present, CHn (n = 0-3), were identified by DEPT NMR and quantified using inverse-gated decoupled C-13 NMR. spectra. The olefinic protons and carbons as well as the types of olefins were quantified. C-13 NMR shows that the amount of methyl carbons is similar for both catalysts but that methylene and methyne carbon distributions are different. The product obtained over MTW catalyst showed higher quantities of quaternary olefins, likely from type V tetrasubstituted olefins, compared to that over SPA catalyst. In addition, 2D NMR has also been attempted to understand the proton and carbon connectivities and confirmed the presence of type I and II olefins.

1H and 13C pulsed field gradient (PFG) NMR was used to study the self-diffusion of heptane in porous alumina exhibiting a hierarchy of pore sizes that cover the range from micropore to macropore sizes. Diffusion measurements were performed for the lengths scales of displacements comparable with and smaller than the sizes of aggregates of porous alumina particles. The measured heptane diffusivities inside the particle aggregates were found to be several times smaller than the diffusivity in the bulk liquid heptane. The diffusivities inside the aggregates were correlated with the aggregate structural characteristics, which include pore volume, pore size and packing density of the individual particles in the aggregates.

UOP layered silicate-1 (ULS-1), a highly siliceous layered silicate composed of [4(2)6(2)] half sodalite cages, has been synthesized hydrothermally at 100 degrees C from solutions containing ethyltrimethylammonium hydroxide and silica or aluminosilicate sources and the structure solved from powder XRD data in the lbam spacegroup with a = 28.909 angstrom, b = 8.380 angstrom, c = 11.569 angstrom at room temperature. TGA/MS and NMR, Raman and IR spectroscopic characterization were utilized to examine the properties of ULS-1 and provide information for structure solution. ULS-1 contains the same silicate layer structure and stacking as that found in RUB-15 and DLM-2, but with ethyltrimethylammonium (ETMA) cations in place of tetramethylammonium stabilizing the half sodalite cages. The presence of ETMA increases the interlayer spacing to similar to 8.3 angstrom from the previously observed 8 angstrom, but also slightly increases the c unit cell constant in the layer direction. (C) 2014 Elsevier Inc. All rights reserved.

In this paper we present and discuss selected results of our recent studies of sorbate self-diffusion in microporous materials. The main focus is given to transport properties of carbon molecular sieve (CMS) membranes as well as of the intergrowth of FAU-type and EMT-type zeolites. CMS membranes show promise for applications in separations of mixtures of small gas molecules, while FAU/EMT intergrowth can be used as an active and selective cracking catalyst. For both types of applications diffusion of guest molecules in the micropore networks of these materials is expected to play an important role. Diffusion studies were performed by a pulsed field gradient (PFG) NMR technique that combines advantages of high field (17.6 T) NMR and high magnetic field gradients (up to 30 T/m). This technique has been recently introduced at the University of Florida in collaboration with the National Magnet Lab. In addition to a more conventional proton PFG NMR, also carbon-13 PFG NMR was used.

Pulsed field gradient (PFG) NMR technique with high (up to 30T/m) gradient amplitudes was employed to study diffusion of isooctane and isobutane in a FAU/EMT intergrowth as well as in the corresponding pure zeolites of the FAU and EMT types. The temperatures and diffusion times used in the measurements were sufficiently small to allow performing diffusion studies for the length scales of sorbate displacements smaller than or comparable with the sizes of the individual zeolite particles. Analysis of the PFG NMR data obtained for the FAU/EMT intergrowth and the comparison of these data with the corresponding results of the measurements of the pure FAU and EMT zeolites revealed the existence of intraparticle transport barriers in the FAU/EMT intergrowth. Partially blocked micropore openings at the interfaces between the intergrowth components of the FAU/EMT particles can be the structural origin of the observed barriers.