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Hani Nasser Abdelhamid, Zhehao Huang, Ahmed M El-Zohry, Haoquan Zheng, Xiaodong Zou
A trimethylamine (TEA)-assisted synthesis approach that combines the preparation of hierarchical porous zeolitic imidazolate framework ZIF-8 nanoparticles and one-pot encapsulation of target molecules is presented. Two dye molecules, rhodamine B (RhB) and methylene blue (MB), and one protein (bovine serum albumin, BSA) were tested as the target molecules. The addition of TEA into the solution of zinc nitrate promoted the formation of ZnO nanocrystals, which rapidly transformed to ZIF-8 nanoparticles after the addition of the linker 2-methylimidazole (Hmim)...
July 17, 2017: Inorganic Chemistry
Junjie Li, Min Liu, Xinwen Guo, Shutao Xu, Yingxu Wei, Zhongmin Liu, Chunshan Song
ZSM-5 that uses TPAOH as a template has an Al-rich exterior and defective Si-rich interior, thus it decouples the alkaline treatment difficulties of Al-rich and Si-rich crystals. Alkaline treatment selectively removed the Si-rich interior while the Al-rich exterior was protected, this catalyst showed no change in stability comparing with parent ZSM-5 during the MTP reaction that attributed to enclosed hollow structure and acidity-rich exterior. Pre-treatment by NH4F, however, both removed defective Si-sites and caused distortion in tetrahedral aluminum that made the outer shell susceptible to alkaline treatment...
July 17, 2017: ACS Applied Materials & Interfaces
Jian-Qiang Zhong, Mengen Wang, Nusnin Akter, John D Kestell, Alejandro M Boscoboinik, Taejin Kim, Dario J Stacchiola, Deyu Lu, J Anibal Boscoboinik
The confinement of noble gases on nanostructured surfaces, in contrast to bulk materials, at non-cryogenic temperatures represents a formidable challenge. In this work, individual Ar atoms are trapped at 300 K in nano-cages consisting of (alumino)silicate hexagonal prisms forming a two-dimensional array on a planar surface. The trapping of Ar atoms is detected in situ using synchrotron-based ambient pressure X-ray photoelectron spectroscopy. The atoms remain in the cages upon heating to 400 K. The trapping and release of Ar is studied combining surface science methods and density functional theory calculations...
July 17, 2017: Nature Communications
Maikel Gilberto Fernández-López, Carolina Popoca-Ursino, Enrique Sánchez-Salinas, Raunel Tinoco-Valencia, Jorge Luis Folch-Mallol, Edgar Dantán-González, Ma Laura Ortiz-Hernández
Organophosphate pesticides are of great interest for research because they are currently the most commonly used pesticides. In this study, a bacterial strain capable of completely degrading methyl parathion (MP) was isolated from agricultural soils in central Mexico. This strain was designated strain S5-2 and was identified as Burkholderia cenocepacia. To increase degradation yields, cells were immobilized on three different supports: powdered zeolite and Opuntia sp. and Agave sp. fibers. The results indicated a significant increase in MP hydrolysis and p-nitrophenol (PNP) degradation with immobilized cells compared to free cell cultures...
July 17, 2017: MicrobiologyOpen
Nicolas Duyckaerts, Mathias Bartsch, Ioan-Teodor Trotus, Norbert Pfänder, Axel Lorke, Ferdi Schüth, Gonzalo Prieto
Tandem catalysis is an attractive strategy to intensify chemical processes but simultaneous control over the individual and concerted catalyst performances poses a challenge. We show that enhanced pore transport within a Co/Al2O3 Fischer-Tropsch (FT) catalyst with a hierarchical porosity enables its tandem integration with a Pt/ZSM-5 zeolitic hydrotreating catalyst in a spatially distant fashion - permitting a catalyst-specific temperature adjustment - albeit resembling a close active site proximity - by mitigating secondary reactions of primary FT α-olefin products...
July 16, 2017: Angewandte Chemie
Alexey V Kubarev, Eric Breynaert, Jordi Van Loon, Arunasish Layek, Guillaume Fleury, Sambhu Radhakrishnan, Johan Martens, Maarten B J Roeffaers
Molecular-sized micropores of ZSM-5 zeolite catalysts provide spatial restrictions around catalytic sites that allow for shape-selective catalysis. However, the fact that ZSM-5 has two main pore systems with different geometries is relatively unexploited as a potential source of additional shape selectivity. Here, we use confocal laser-scanning microscopy to show that by changing the polarity of the solvent, the acid-catalyzed furfuryl alcohol oligomerization can be directed to selectively occur within either of two locations in the microporous network...
July 7, 2017: ACS Catalysis
Mashaallah Rahmani, Massoud Kaykhaii, Mojtaba Sasani
This study aimed to investigate the efficiency of 3A zeolite as a novel adsorbent for removal of Rhodamine B and Malachite green dyes from water samples. To increase the removal efficiency, effecting parameters on adsorption process were investigated and optimized by adopting Taguchi design of experiments approach. The percentage contribution of each parameter on the removal of Rhodamine B and Malachite green dyes determined using ANOVA and showed that the most effective parameters in removal of RhB and MG by 3A zeolite are initial concentration of dye and pH, respectively...
July 1, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Avelino Corma, Nuria Martin Garcia, Peter Vennestrom, Joakim Reimer, Manuel Moliner
The direct preparation of different Fe-containing Beta and CHA zeolites has been attempted under diverse synthesis conditions, including alkaline and fluoride media, to evaluate the influence of their physico-chemical properties on the selective catalytic reduction (SCR) of NOx using NH3 as a reductant. From the different Fe-Beta zeolites, the sample prepared in absence of alkali-cations with a Si/Al~13, shows high NO conversion values (> 90%). However, this catalyst suffers from severe deactivation when aged at high temperatures in the presence of steam...
July 14, 2017: Chemistry: a European Journal
Saman Samadi, Shabnam Sharif Yazd, Hossein Abdoli, Pooya Jafari, Majid Aliabadi
In the present study, the chitosan (bottom layer)/polyacrylonitrile (top layer, PAN) nanofibers were coated on the sponge surface. The synthesized magnetic Fe3O4- ZSM-5 nanozeolites have been loaded into the chitosan/PAN nanofibers to increase the performance of nanofibers toward absorption of lubricating oil, motor oil and pump oil from water surfaces. scanning electron microscope (SEM), Transmission electron microscope (TEM) and X-ray diffraction (XRD) analysis were used to characterize the synthesized nanozeolites...
July 10, 2017: International Journal of Biological Macromolecules
Markus Dietrich, Gunter Hagen, Willibald Reitmeier, Katharina Burger, Markus Hien, Philippe Grass, David Kubinski, Jaco Visser, Ralf Moos
The upcoming more stringent automotive emission legislations and current developments have promoted new technologies for more precise and reliable catalyst control. For this purpose, radio-frequency-based (RF) catalyst state determination offers the only approach for directly measuring the NH₃ loading on selective catalytic reduction (SCR) catalysts and the state of other catalysts and filter systems. Recently, the ability of this technique to directly control the urea dosing on a current NH₃ storing zeolite catalyst has been demonstrated on an engine dynamometer for the first time and this paper continues that work...
July 12, 2017: Sensors
Jelena Milenkovic, Jasna Hrenovic, Danka Matijasevic, Miomir Niksic, Nevenka Rajic
Two types of zeolites-natural clinoptilolite (NZ) and synthetic zeolite A (A)-were enriched with approx. 0.25 mmol of Cu(II), Zn(II), or Ag(I) ions, and the obtained materials (M-Z) were tested against three different isolates of Escherichia coli. Two isolates were environmental isolates from waters in Serbia whereas the third one was DSM 498. Antibacterial activity was studied in different water media-nutrient-rich media (peptone water), water from Sava Lake, and commercially available spring water. The Ag-containing zeolites showed bactericidal activity in the nutrient-rich peptone water after 1 h of contact...
July 13, 2017: Environmental Science and Pollution Research International
Meijing Wang, Mukesh Kumar Awasthi, Quan Wang, Hongyu Chen, Xiuna Ren, Junchao Zhao, Ronghua Li, Zengqiang Zhang
In this study, the pilot scale co-composting of sewage sludge (SS)+wheat straw amended with 10% (dry weight ratio of basis) of three different additives (zeolite, Ca-bentonite and medical stone) was conducted for 56days to evaluate the greenhouse gases (GHGs) and nitrogen conservation efficacy and its correlation with analyzed physicochemical, gaseous and biological parameters. The results indicated that all of three additives could adequately buffer pH, considerably increase temperature, and enhance organic matter degradation as well as reduce ammonia and GHGs emission...
June 30, 2017: Bioresource Technology
Bruno Azambre, Mouheb Chebbi
In this study, up to 13 different silver zeolites sorbents were prepared by repeated ion-exchange from their parent structures (FAU X and Y, MOR, *BEA, MFI, FER), characterized and evaluated for their ability to capture methyl iodide in the context of nuclear severe accident. A novel methodology was implemented to establish structure-activity relationships between sorbent properties and iodine trapping stability. After saturation of the zeolite bed with CH3I during a dynamic breakthrough experiment at 100°C, a two-steps quantitative desorption method was elaborated with the aim to quantify separately the CH3I fractions trapped by physisorption, chemisorption or reacted as AgI precipitates...
July 11, 2017: ACS Applied Materials & Interfaces
Shuang Wang, Youssef Belmabkhout, Amy J Cairns, Guanghua Li, Qisheng Huo, Yunling Liu, Mohamed Eddaoudi
A strategy based on metal-ligand directed assembly of metal-organic squares (MOSs), built-up from four-membered ring (4MR) secondary building units (SBUs), has been employed for the design and construction of isoreticular zeolite-like supramolecular assemblies (ZSAs). Four porous Co-based ZSAs having the same underlying gis topology, but differing only with respect to the capping and bridging linkers, were successfully isolated and fully characterized. In this series, each MOS in ZSA-3-ZSA-6 possess an ideal square geometry and is connected to four neighboring MOS via a total of 16 hydrogen bonds to give a 3-periodic porous network...
July 11, 2017: ACS Applied Materials & Interfaces
Shufang Ji, Chen Yuanjun, Qiang Fu, Yifeng Chen, Juncai Dong, Wenxing Chen, Zhi Li, Yu Wang, Lin Gu, Wei He, Chen Chen, Qing Peng, Yu Huang, Xiangfeng Duan, Dingsheng Wang, Claudia Draxl, Yadong Li
Here we report a novel approach to synthesize atomically dispersed uniform clusters via a cage-separated precursor-preselected pyrolysis strategy. To illustrate this strategy, well-defined Ru3(CO)12 was separated as a precursor by suitable molecular-scale cages of zeolite-imidazolate frameworks (ZIFs). Followed by a thermal treatment under confinement of cages, atomically dispersed uniform Ru3 clusters stabilized by nitrogen species (Ru3/CN) were obtained. Importantly, we found that Ru3/CN exhibits excellent catalytic activity (100% conversion),high chemoselectivity (100% for 2-aminobenzaldehyde) and significantly high turnover fre-quency (TOF) for oxidation of 2-aminobenzylalcohol...
July 11, 2017: Journal of the American Chemical Society
Xin Liu, Yuan Sun, Jingjing Liu, Cheng-Gong Sun, Hao Liu, Qian Xue, Emily F Smith, Colin E Snape
Novel hierarchically structured microporous bio-carbons with exceptionally high capacities for CO2 capture have been synthesized from the abundant agricultural waste of rice husk (RH), using a facile methodology that effectively integrated carbonisation, activation and potassium intercalation into a one-step process. Textural characterisation demonstrates that the synthesized bio-carbons exhibit exceedingly high ultra-microporosity accounting for up to 95% of total porosity mainly as a result of the naturally occurring silicon compounds within the RH molecular framework structures...
July 11, 2017: ACS Applied Materials & Interfaces
Xin Zhang, Junyu Chen, Xiang Pei, Jian Wang, Qianbing Wan, Shaokang Jiang, Chao Huang, Xibo Pei
Nanoscale zeolitic imidazolate framework-8 (ZIF-8)-modified titanium (ZIF-8@AHT) can enhance osteogenesis in vitro. In this study, we systematically and quantitatively examined the effects of ZIF-8@AHT on osteogenesis, and investigated its ability to form bone in vivo. First, we coated various quantities of nanoscale ZIF-8 crystals on alkali- and heat-treated titanium (AHT) by controlling the concentration of the synthesis solution. We then characterized the ZIF-8@AHT materials using scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), and determination of the sessile drop contact angle...
July 11, 2017: ACS Applied Materials & Interfaces
Eliska Rezlerova, Arnost Zukal, Jiri Cejka, Flor R Siperstein, John Kennedy Brennan, Martin Lisal
We employ grand canonical Monte Carlo and molecular dynamics simulations to systematically study adsorption and diffusion of C1 to C4 alkanes in hierarchical ZSM-5 zeolite with micro- (~1nm) and mesopores (>2nm). The zeolite is characterized by a large surface area of active sites at the microporous scale with high permeability and access to the active sites, which arises from the enhanced transport at the mesoporous scale. We model this zeolite as a microporous Na+ exchanged alumino-sillicate zeolite ZSM-5/35 (Si/Al=35) in which cylindrical mesopores with diameter of 4nm have been built by deleting atoms accordingly...
July 9, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Mansi S Shah, Michael Tsapatsis, J Ilja Siepmann
Hydrogen sulfide removal is a long-standing economic and environmental challenge faced by the oil and gas industries. H2S separation processes using reactive and non-reactive absorption and adsorption, membranes, and cryogenic distillation are reviewed. A detailed discussion is presented on new developments in adsorbents, such as ionic liquids, metal oxides, metals, metal-organic frameworks, zeolites, carbon-based materials, and composite materials; and membrane technologies for H2S removal. This Review attempts to exhaustively compile the existing literature on sour gas sweetening and to identify promising areas for future developments in the field...
July 5, 2017: Chemical Reviews
N Manicke, S Hoof, M Keck, B Braun-Cula, M Feist, C Limberg
A hexanuclear iron(II) siloxide complex has been prepared by reacting an incompletely condensed silsesquioxane first with NaOMe and then with Fe(OTf)2. In the process of product formation, the siloxane framework undergoes a transformation and it was shown that this happens already upon addition of base: Treatment of the ligand precursor with NaOMe leads to a completely condensed silsesquioxane cage with 12 Si atoms that is composed of 2 equiv of the tetrasiloxide ligands found in the product complex. Its iron centers form a two-dimensional array reminiscent of the situations found in minerals and two-dimensional oxide films caused by segregation of FeOx and silica...
July 17, 2017: Inorganic Chemistry
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