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https://www.readbyqxmd.com/read/28106987/constructing-ultraporous-covalent-organic-frameworks-in-seconds-via-an-organic-terracotta-process
#1
Suvendu Karak, Sharath Kandambeth, Bishnu P Biswal, Himadri Sekhar Sasmal, Sushil Kumar, Pradip Pachfule, Rahul Banerjee
Research on covalent organic frameworks (COFs) has recently gathered significant momentum by the virtue of their predictive design, controllable porosity and long range ordering. However, the lack of solvent free and easy-to-perform synthesis processes appears to be the bottleneck towards their greener fabrication, thereby limiting their possible potential applications. To alleviate such shortcomings, we demonstrate a simple route towards the rapid synthesis of highly crystalline and ultraporous COFs in seconds using a novel salt-mediated crystallization approach...
January 20, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28106376/an-efficient-bi-functional-electrocatalyst-for-zinc-air-battery-derived-by-fe-n-c-and-bimetallic-metal-organic-frameworks-composites
#2
Mengfan Wang, Tao Qian, Jinqiu Zhou, Chenglin Yan
Efficient bi-functional electrocatalysts with desirable oxygen activities are closely related to practical applications of renewable energy systems including metal-air batteries, fuel cells, and water splitting. Here, a composite material derived from the combination of bimetallic zeolitic imidazolate frameworks (denoted as BMZIFs) and Fe/N/C framework was reported as an efficient bi-functional catalyst. Although BMZIF or Fe/N/C alone exhibits undesirable oxygen reaction activity, their combined materials show unprecedented ORR (half-wave potential of 0...
January 20, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28101727/reliable-prediction-of-adsorption-isotherms-via-genetic-algorithm-molecular-simulation
#3
L LoftiKatooli, A Shahsavand
Conventional molecular simulation techniques such as grand canonical Monte Carlo (GCMC) strictly rely on purely random search inside the simulation box for predicting the adsorption isotherms. This blind search is usually extremely time demanding for providing a faithful approximation of the real isotherm and in some cases may lead to non-optimal solutions. A novel approach is presented in this article which does not use any of the classical steps of the standard GCMC method, such as displacement, insertation, and removal...
January 2017: Journal of Molecular Modeling
https://www.readbyqxmd.com/read/28098276/direct-white-light-emitting-and-near-infrared-phosphorescence-of-zeolitic-imidazolate-framework-8
#4
Xiaogang Yang, Dongpeng Yan
Zeolitic imidazolate framework-8 directly exhibits unexpected white-light emission and near-infrared (NIR) phosphorescence, due to the host-guest interaction and the alternation of electron-density distribution, as confirmed by both experimental and computational studies.
January 18, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28097753/fully-copper-exchanged-high-silica-lta-zeolites-as-unrivaled-hydrothermally-stable-nh3-scr-catalysts
#5
Taekyung Ryu, Nak Ho Ahn, Seungwan Seo, Jung Cho, Hyojun Kim, Donghui Jo, Gi Tae Park, Pyung Soon Kim, Chang Hwan Kim, Elliott L Bruce, Paul A Wright, In-Sik Nam, Suk Bong Hong
Diesel engine technology is still the most effective solution to meet tighter CO2 regulations in the mobility and transport sector. In implementation of fuel-efficient diesel engines, the poor thermal durability of lean nitrogen oxides (NOx ) aftertreatment systems remains as one major technical hurdle. Divalent copper ions when fully exchanged into high-silica LTA zeolites are demonstrated to exhibit excellent activity maintenance for NOx reduction with NH3 under vehicle simulated conditions even after hydrothermal aging at 900 °C, a critical temperature that the current commercial Cu-SSZ-13 catalyst cannot overcome owing to thermal deactivation...
January 18, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28096342/eight-coordinate-fluoride-in-a-silicate-double-four-ring
#6
Maarten G Goesten, Roald Hoffmann, F Matthias Bickelhaupt, Emiel J M Hensen
Fluoride, nature's smallest anion, is capable of covalently coordinating to eight silicon atoms. The setting is a simple and common motif in zeolite chemistry: the box-shaped silicate double-four-ring (D4R). Fluoride seeks its center. It is the strain of box deformation that keeps fluoride in the middle of the box, and freezes what would be a transition state in its absence. Hypervalent bonding ensues. Fluoride's compactness works to its advantage in stabilizing the cage; chloride, bromide, and iodide do not bring about stabilization due to greater steric repulsion with the box frame...
January 17, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28091996/zeolitic-tuffs-for-acid-mine-drainage-amd-treatment-in-ecuador-breakthrough-curves-for-mn-2-cd-2-cr-3-zn-2-and-al-3
#7
Xavier Buenaño, Laureano Canoira, Domingo Martin Sánchez, Jorge Costafreda
Zeolitic tuff constitutes a technical and economical feasible alternative to manage acidic waters in initial phases of generation. A study of cation exchange with two zeolitic tuffs from Ecuador and one from Cuba has been conducted using breakthrough curve methodology. Cations Mn(2+), Cd(2+), Cr(3+), Zn(2+), and Al(3+) have been chosen owing to their presence in underground water in exploration activities (decline development) in Fruta del Norte (Ecuador). Zeolites characterized by X-ray diffraction and thermal stability after heating overnight as heulandites show a similar exchange behavior for the five cations studied...
January 14, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28090685/zeolite-based-organic-synthesis-zeobos-of-acortatarin-a-first-total-synthesis-based-on-native-and-metal-doped-zeolite-catalyzed-steps
#8
Eric Wimmer, Sophie Borghèse, Aurélien Blanc, Valérie Bénéteau, Patrick Pale
Similarly to polymer-supported assisted synthesis (PSAS), organic synthesis could be envisaged being performed by using zeolites, native or metal-doped, as heterogeneous catalysts. To illustrate this unprecedented Zeolite-Based Organic Synthesis (ZeoBOS), the total synthesis of acortatarin A was achieved through a novel strategy and using five out of eleven synthetic steps catalyzed by H- or metal-doped zeolites as catalysts. Notably, the formation of an yne-pyrrole intermediate with a copper-doped zeolite and the spiroketalization of an alkyne diol with a silver-doped zeolite have been developed as key steps of the synthesis...
November 6, 2016: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28089276/simultaneous-separation-of-neutral-and-cationic-analytes-by-one-dimensional-open-tubular-capillary-electrochromatography-using-zeolitic-imidazolate-framework-8-as-stationary-phase
#9
Congjie Pan, Wenjuan Lv, Guoxiu Wang, Xiaoying Niu, Heying Guo, Xingguo Chen
Developing simple methods for separation of analytes that belong to different classes is of great importance. Herein, we developed a simple one-dimensional (1-D) capillary electrochromatography method to demonstrate the simultaneous separation of target fractions that belong to two different classes (i.e., cationic and neutral analytes) without switching buffer solution by a zeolitic imidazolate framework ZIF-8 coated capillary column. Owing to the difference of charge-to-mass ratio of the cationic analytes, the interaction of the cationic analytes and coating material ZIF-8 and the hydrophobic interactions between the neutral analytes and the microporous framework of ZIF-8, six cationic analytes and four neutral analytes were simultaneously separated in a single run by 1-D capillary electrochromatography...
January 11, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28089089/-27-al-27-al-double-quantum-single-quantum-mas-nmr-applications-to-the-structural-characterization-of-microporous-materials
#10
REVIEW
Charlotte Martineau-Corcos, Jiri Dědeček, Francis Taulelle
In this paper, we review and illustrate applications, reported in the literature or used in our group, of (27)Al-(27)Al double-quantum single-quantum (DQ-SQ) MAS NMR experiments for the structural characterization of Al-containing microporous solids, namely zeolites, aluminophosphates and metal-organic frameworks. Information regarding the periodic frameworks or the localization of the various aluminum species in the materials are obtained from the analysis of the two-dimensional NMR spectra, which allows getting local structural details sometimes inaccessible from other characterization technique...
December 28, 2016: Solid State Nuclear Magnetic Resonance
https://www.readbyqxmd.com/read/28088567/simple-fabrication-of-zeolitic-imidazolate-framework-zif-8-polymer-composite-beads-by-phase-inversion-method-for-efficient-oil-sorption
#11
Zahra Abbasi, Ezzatollah Shamsaei, Xi-Ya Fang, Bradley Ladewig, Huanting Wang
Zeolitic imidazolate framework ZIF-8 beads of 2-3mm in diameter were prepared using a simple one-step phase inversion method. The beads were fabricated by different amounts of ZIF-8 to polyether sulfone (PES) ratios. ZIF-8 played the role of an adsorbent while PES acted as a binder in the composite matrix to keep the ZIF-8 particles. Since ZIF-8 is highly hydrophobic, the beads floated on water and adsorbed oil droplets successfully. This efficient oil adsorption is attributed to the hydrophobicity and high surface area of ZIF-8 particles which can effectively adsorb oil droplets...
January 5, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28079200/a-molecular-dynamics-study-of-the-interaction-of-water-with-the-external-surface-of-silicalite-1
#12
Konstantin S Smirnov
The interaction of water with the hydroxylated (010) surface of silicalite-1 was studied by classical molecular dynamics simulations. Interatomic interactions in the system were described using a set of effective potentials combining well-tested BKS and SPC models. The extended force field is shown to correctly reproduce the structural, energy, and dynamical characteristics of the silica surface OH groups. The interaction of water with the hydrophilic silanols leads to an ordering of H2O molecules in the vicinity of the surface...
January 12, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28075058/mof-derived-hollow-cage-nix-co3-x-o4-and-their-synergy-with-graphene-for-outstanding-supercapacitors
#13
Anjali Jayakumar, Rajini P Antony, Ronghua Wang, Jong-Min Lee
Highly optimized nickel cobalt mixed oxide has been derived from zeolite imidazole frameworks. While the pure cobalt oxide gives only 178.7 F g(-1) as the specific capacitance at a current density of 1 A g(-1) , the optimized Ni:Co 1:1 has given an extremely high and unprecedented specific capacitance of 1931 F g(-1) at a current density of 1 A g(-1) , with a capacitance retention of 69.5% after 5000 cycles in a three electrode test. This optimized Ni:Co 1:1 mixed oxide is further used to make a composite of nickel cobalt mixed oxide/graphene 3D hydrogel for enhancing the electrochemical performance by virtue of a continuous and porous graphene conductive network...
January 11, 2017: Small
https://www.readbyqxmd.com/read/28069234/ultrasonic-assisted-synthesis-of-bikitaite-zeolite-a-potential-material-for-hydrogen-storage-application
#14
Priyanka Roy, Nandini Das
Li containing Bikitaite zeolite has been synthesized by an ultrasound-assisted method and used as a potential material for hydrogen storage application. The Sonication energy was varied from 150W to 250W and irradiation time from 3h to 6h. The Bikitaite nanoparticles were characterized by X-ray diffraction (XRD), infrared (IR) spectral analysis, and field-emission scanning electron microscopy (FESEM) thermo-gravimetrical analysis and differential thermal analysis (TGA, DTA). XRD and IR results showed that phase pure, nano crystalline Bikitaite zeolites were started forming after 3h irradiation and 72h of aging with a sonication energy of 150W and nano crystalline Bikitaite zeolite with prominent peaks were obtained after 6h irradiation of 250W sonic energy...
May 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28067993/on-the-structure-property-relationships-of-cation-exchanged-zk-5-zeolites-for-co2-adsorption
#15
Trong Pham, Raul Lobo, Matthew Hudson, Craig Brown
The CO2 adsorption properties of cation-exchanged Li-, Na-, K-, and Mg-ZK-5 zeolites are correlated to the molecular structures determined by Rietveld refinements of synchrotron powder X-ray diffraction patterns. Li-, K-, and Na-ZK-5 all exhibit high isosteric heats of adsorption (Qst) at low CO2 coverage, with Na-ZK-5 having the highest Qst (≈49 kJ/mol). Mg2+ is located at the center of the zeolite hexagonal prism, with the cation inaccessible to CO2, leading to a much lower Qst (≈30 kJ/mol) and lower overall uptake capacity...
January 9, 2017: ChemSusChem
https://www.readbyqxmd.com/read/28067444/irreversible-conversion-of-a-water-ethanol-solution-into-an-organized-two-dimensional-network-of-alternating-supramolecular-units-in-a-hydrophobic-zeolite-under-pressure
#16
Rossella Arletti, Ettore Fois, Lara Gigli, Giovanna Vezzalini, Simona Quartieri, Gloria Tabacchi
Turning disorder into organization is a key issue in science. By making use of X-ray powder diffraction and modeling studies, we show herein that high pressures in combination with the shape and space constraints of the hydrophobic all-silica zeolite ferrierite separate an ethanol-water liquid mixture into ethanol dimer wires and water tetramer squares. The confined supramolecular blocks alternate in a binary two-dimensional (2D) architecture that remains stable upon complete pressure release. These results support the combined use of high pressures and porous networks as a viable strategy for driving the organization of molecules or nano-objects towards complex, pre-defined patterns relevant for the realization of novel functional nanocomposites...
January 9, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28066888/technical-note-a-new-zeolite-pet-phantom-to-test-segmentation-algorithms-on-heterogeneous-activity-distributions-featured-with-ground-truth-contours
#17
Chiara D Soffientini, Elisabetta De Bernardi, Rosangela Casati, Giuseppe Baselli, Felicia Zito
PURPOSE: Design, realization, scan, and characterization of a phantom for PET Automatic Segmentation (PET-AS) assessment are presented. Radioactive zeolites immersed in a radioactive heterogeneous background simulate realistic wall-less lesions with known irregular shape and known homogeneous or heterogeneous internal activity. METHOD: Three different zeolite families were evaluated in terms of radioactive uptake homogeneity, necessary to define activity and contour ground truth...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28057339/mechanism-and-performance-for-adsorption-of-2-chlorophenol-onto-zeolite-with-surfactant-by-one-step-process-from-aqueous-phase
#18
Sha Peng, Zheng Tang, Wei Jiang, Di Wu, Song Hong, Baoshan Xing
To decrease the power, material, and time consumption in wastewater treatment, a one-step process was performed to remove 2-chlorophenol (2-CP) from aqueous phase using zeolite and cetyltrimethylammonium bromide (CTAB). Compared with the traditional two-step process, the one-step process used in this study achieved almost eight times higher 2-CP adsorption capacity within a shorter time and maintained high removal efficiencies (around 65%) in reuse tests, thus becoming an efficient and economically acceptable alternative process...
January 2, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28056750/effective-removal-of-penicillin-from-aqueous-solution-using-zinc-oxide-natural-zeolite-composite-nano-powders-prepared-via-ball-milling-technique
#19
Majid Ghashang, Peyman Khosravian, Hamid Ghayoor
In this study, a nano-composite of zinc oxide/natural-Zeolite was synthesized by mechanical method. The obtained microstructure was characterized by FE-SEM, XRD, EDX, and DLS techniques. Two different phases were identified in XRD patterns as hexagonal ZnO and orthorhombic Zeolite with the average crystal size of 86 and 141 nm respectively. The prepared nanocomposite consists of uniform particles with the mean diameter of near 91 nm. The prepared nanocomposite is used for the removal of penicillin from aqueous solution...
January 5, 2017: Recent Patents on Nanotechnology
https://www.readbyqxmd.com/read/28054746/seed-assisted-synthesis-of-mww-type-zeolite-with-organic-structure-directing-agent-free-na-aluminosilicate-gel-system
#20
Yoshihiro Kamimura, Keiji Itabashi, Yoshihiro Kon, Akira Endo, Tatsuya Okubo
Seed-assisted synthesis of zeolite without using organic structure-directing agents (OSDAs) has enabled alternative routes to simple, environmentally friendly and low-cost production of industrially important zeolites. In this study, the successful seed-assisted synthesis of MCM-22 (MWW-type) zeolite with OSDA-free gel is reported for first time. MWW-type zeolite is obtained by the addition of as-synthesized MCM-22 seeds prepared with hexamethyleneimine (HMI) into OSDA-free Na-aluminosilicate gels. Based on the results of XRD, ICP-AES, NMR, N₂ physisorption and NH₃-TPD, product exhibited different features compared to those of the seeds...
January 5, 2017: Chemistry, An Asian Journal
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