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  Subjects -> PHYSICS (Total: 774 journals)
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PHYSICS (563 journals)            First | 1 2 3 4 5 6 | Last

Journal of Porous Materials     Hybrid Journal   (Followers: 3)
Journal of Porphyrins and Phthalocyanines     Hybrid Journal   (Followers: 2)
Journal of Quantitative Spectroscopy and Radiative Transfer     Hybrid Journal  
Journal of Reinforced Plastics and Composites     Hybrid Journal   (Followers: 5)
Journal of Research in Physics     Open Access  
Journal of Rheology     Full-text available via subscription   (Followers: 6)
Journal of Romance Studies     Full-text available via subscription   (Followers: 2)
Journal of Sandwich Structures and Materials     Hybrid Journal   (Followers: 1)
Journal of Scientific Research     Open Access   (Followers: 1)
Journal of Semiconductors     Full-text available via subscription   (Followers: 2)
Journal of Sensors     Open Access   (Followers: 7)
Journal of Sol-Gel Science and Technology     Hybrid Journal   (Followers: 2)
Journal of Solid State Lighting     Open Access  
Journal of Solid State Physics     Open Access  
Journal of Spectroscopy     Open Access  
Journal of Superconductivity and Novel Magnetism     Partially Free   (Followers: 1)
Journal of Synchrotron Radiation     Hybrid Journal   (Followers: 1)
Journal of Testing and Evaluation     Full-text available via subscription   (Followers: 11)
Journal of the American Society for Mass Spectrometry     Hybrid Journal   (Followers: 20)
Journal of the Brazilian Society of Mechanical Sciences     Open Access   (Followers: 1)
Journal of the ICRU     Hybrid Journal  
Journal of the Korean Physical Society     Partially Free   (Followers: 1)
Journal of Theoretical and Applied Physics     Open Access   (Followers: 1)
Journal of Tissue Engineering     Open Access   (Followers: 4)
Journal of Ultrasound in Medicine     Full-text available via subscription   (Followers: 4)
Journal of Vibration and Control     Hybrid Journal   (Followers: 27)
Journal of Visualization     Hybrid Journal   (Followers: 2)
Journal of Zhejiang University SCIENCE A     Hybrid Journal  
Jurnal Penelitian Sains (JPS)     Open Access  
Language Learning Journal     Hybrid Journal   (Followers: 13)
Lasers in Surgery and Medicine     Hybrid Journal  
Latvian Journal of Physics and Technical Sciences     Open Access  
Learning Technologies, IEEE Transactions on     Hybrid Journal   (Followers: 10)
Les Houches Summer School Proceedings     Full-text available via subscription  
Letters in Mathematical Physics     Hybrid Journal   (Followers: 3)
Light : Science & Applications     Open Access  
Living Reviews in Relativity     Open Access  
Living Reviews in Solar Physics     Open Access  
Lubrication Science     Hybrid Journal  
Macalester Journal of Physics and Astronomy     Open Access  
Machining Science and Technology: An International Journal     Hybrid Journal   (Followers: 2)
Magnetic Resonance Materials in Physics, Biology and Medicine     Hybrid Journal   (Followers: 1)
Magnetics Letters, IEEE     Hybrid Journal   (Followers: 4)
MAPAN     Hybrid Journal  
Mass Spectrometry Reviews     Hybrid Journal   (Followers: 21)
Matéria (Rio de Janeiro)     Open Access   (Followers: 1)
Materials & Design     Hybrid Journal   (Followers: 36)
Materials at High Temperatures     Full-text available via subscription   (Followers: 4)
Materials Chemistry and Physics     Full-text available via subscription   (Followers: 13)
Materials Research     Open Access   (Followers: 7)
Materials Research Bulletin     Hybrid Journal   (Followers: 18)
Materials Research Innovations     Hybrid Journal   (Followers: 2)
Materials Science     Hybrid Journal   (Followers: 9)
Materials Science and Engineering: A     Hybrid Journal   (Followers: 36)
Materials Science and Engineering: B     Hybrid Journal   (Followers: 19)
Materials Science and Engineering: C     Hybrid Journal   (Followers: 18)
Materials Science and Engineering: R: Reports     Hybrid Journal   (Followers: 12)
Materials Science and Technology     Hybrid Journal   (Followers: 23)
Matériaux & Techniques     Full-text available via subscription   (Followers: 1)
Mathematical Physics, Analysis and Geometry     Hybrid Journal   (Followers: 1)
Mathematics and Mechanics of Solids     Hybrid Journal   (Followers: 2)
Meccanica     Hybrid Journal   (Followers: 1)
Mechanics of Advanced Materials and Structures     Hybrid Journal   (Followers: 3)
Mechanics of Materials     Hybrid Journal   (Followers: 12)
Mechanics of Time-Dependent Materials     Hybrid Journal   (Followers: 1)
Mechanics Research Communications     Hybrid Journal   (Followers: 2)
Metamaterials     Hybrid Journal   (Followers: 2)
Micro and Nano Systems Letters     Open Access   (Followers: 4)
Microfluidics and Nanofluidics     Hybrid Journal   (Followers: 10)
Microporous and Mesoporous Materials     Hybrid Journal   (Followers: 3)
Modern Instrumentation     Open Access   (Followers: 3)
Modern Physics Letters A     Hybrid Journal   (Followers: 1)
Modern Physics Letters B     Hybrid Journal  
Molecular Diversity     Hybrid Journal  
Moscow University Physics Bulletin     Hybrid Journal  
Multibody System Dynamics     Hybrid Journal   (Followers: 1)
NANO     Hybrid Journal   (Followers: 8)
Nano Letters     Full-text available via subscription   (Followers: 51)
Nano Reviews     Open Access   (Followers: 17)
NanoBioImaging     Open Access  
Nanomechanics     Open Access  
Nanoscale and Microscale Thermophysical Engineering     Hybrid Journal   (Followers: 3)
Nanoscale Research Letters     Open Access   (Followers: 4)
Nanospectroscopy     Open Access  
Nanotechnology Magazine, IEEE     Full-text available via subscription   (Followers: 18)
Natural Science     Open Access   (Followers: 9)
Nature Communications     Open Access   (Followers: 48)
Nature Materials     Full-text available via subscription   (Followers: 50)
Nature Physics     Full-text available via subscription   (Followers: 28)
NDT & E International     Hybrid Journal   (Followers: 14)
NEUTRINO     Open Access  
Neutron News     Hybrid Journal  
New Journal of Physics     Open Access   (Followers: 7)
Niels Bohr Collected Works     Full-text available via subscription  
Noise & Vibration Worldwide     Full-text available via subscription   (Followers: 5)
Noise Notes     Full-text available via subscription   (Followers: 3)
Nondestructive Testing And Evaluation     Hybrid Journal   (Followers: 7)
Nonlinear Dynamics     Hybrid Journal   (Followers: 5)
NTM Zeitschrift für Geschichte der Wissenschaften, Technik und Medizin     Hybrid Journal   (Followers: 4)
Nuclear Engineering and Design     Hybrid Journal   (Followers: 12)

  First | 1 2 3 4 5 6 | Last

Journal Cover   Microporous and Mesoporous Materials
  [SJR: 1.306]   [H-I: 102]   [5 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1387-1811
   Published by Elsevier Homepage  [2588 journals]
  • Adsorptive removal of triarylmethane dye (Basic Red 9) from aqueous
           solution by sepiolite as effective and low-cost adsorbent
    • Abstract: Publication date: 1 July 2015
      Source:Microporous and Mesoporous Materials, Volume 210
      Author(s): Osman Duman , Sibel Tunç , Tülin Gürkan Polat
      In this study, the adsorption of Basic Red 9 (BR9) from aqueous solution onto sepiolite was investigated. Batch experiments were carried out to determine the effects of various parameters including contact time, initial dye concentration, temperature and pH on the adsorptive removal of BR9 by sepiolite. Both kinetic and isotherm data were obtained. The kinetic and isotherm data fitted very well with the pseudo second-order kinetic model and Freundlich isotherm model, respectively. The calculated thermodynamic parameters indicated that the adsorption process was spontaneous, favorable, and exothermic. The pH of dye solution and electrostatic interaction do not play an important role on the adsorption process. The increase in the adsorption amount of BR9 led to a decrease in the zeta potential of sepiolite. The interaction between sepiolite and BR9 was investigated by Fourier transform infrared (FTIR) spectroscopy. Desorption of BR9 from spent adsorbent was studied in water, ethyl alcohol and benzyl alcohol. The highest desorption amount was obtained by benzyl alcohol. This study revealed that sepiolite could be used as effective and low-cost adsorbent in the treatment of wastewater contaminated with triarylmethane dyes.
      Graphical abstract image

      PubDate: 2015-03-17T11:05:36Z
       
  • Progressive weakening of zeolite granules due to cyclic moisture loading
           and unloading
    • Abstract: Publication date: 15 July 2015
      Source:Microporous and Mesoporous Materials, Volume 211
      Author(s): Peter Mueller , Alexander Russell , Jakob Seidenbecher , Juergen Tomas
      The influence of moisture content and cyclic moisture loading and unloading on the mechanical properties like the strength of three different types of zeolite granules has been studied by uniaxial compression tests. The tested granules had been processed using different contents of binder and different thermal drying/activation temperatures. A moistening–drying cycle consists of moistening the granules in a climate chamber using wet air and complete immersion in a water bath followed by thermal drying in a drying chamber at 350–400 °C. The experimentally recorded force–displacement curves and digital images of the granule and fracture surfaces recorded using scanning electron microscopy are evaluated and discussed. With increasing number of moistening–drying cycles, a continuous decrease in the strength of granules take place due to non-regenerative damage of the structure. However, a critically constant strength level is more or less reached after ten cycles.
      Graphical abstract image

      PubDate: 2015-03-17T11:05:36Z
       
  • Porous silicon nanoparticles as efficient sensitizers for sonodynamic
           therapy of cancer
    • Abstract: Publication date: 1 July 2015
      Source:Microporous and Mesoporous Materials, Volume 210
      Author(s): L.A. Osminkina , A.L. Nikolaev , A.P. Sviridov , N.V. Andronova , K.P. Tamarov , M.B. Gongalsky , A.A. Kudryavtsev , H.M. Treshalina , V.Yu. Timoshenko
      Luminescent porous silicon nanoparticles with mean size of about 100 nm were covered by biodegradable polymer (dextran) and were investigated as potential sensitizers for ultrasound-assisted therapy. Luminescent confocal microscopy revealed an efficient uptake of the nanoparticles by cancer cells in vitro. The nanoparticles were found to be almost nontoxic up to the concentration of 0.1 mg/mL and doses of 30 mg/kg as it was confirmed by in vitro and in vivo experiments, respectively. A strong suppression of the cancer cell proliferation was observed after a combined treatment by the nanoparticles and therapeutic ultrasound irradiation with frequencies of 1–3 MHz and intensities of 1–2 W/cm2. The obtained results are discussed in view of potential applications of biocompatible and biodegradable silicon-based nanoparticles in sonodynamic therapy of cancer.
      Graphical abstract image

      PubDate: 2015-03-17T11:05:36Z
       
  • Transparent films of metal-organic frameworks for optical applications
    • Abstract: Publication date: 15 July 2015
      Source:Microporous and Mesoporous Materials, Volume 211
      Author(s): Zhi-Gang Gu , Alexander Pfriem , Sebastian Hamsch , Helmut Breitwieser , Jonas Wohlgemuth , Lars Heinke , Hartmut Gliemann , Christof Wöll
      The optical and structural quality of thin films of metal-organic frameworks (MOFs) is of utmost importance for most potential applications as sensors and other optical devices. In this work, a dipping robot equipped with an ultrasonic bath has been developed to prepare thin, homogenous surface-mounted MOFs (SURMOFs) with well-defined thicknesses and orientations. SURMOFs of type HKUST-1, prepared with and without ultrasonication, were characterized by means of XRD, SEM, AFM and UV–vis spectroscopy. It was found that the MOF films prepared with ultrasonication are significantly cleaner, more homogenous and have a considerably smaller surface roughness than MOF films prepared without ultrasonication. The higher film quality results in a tremendously improved transparency, making them perfectly suited for optical applications.
      Graphical abstract image

      PubDate: 2015-03-17T11:05:36Z
       
  • Phosphotungstic acid encapsulated in metal-organic framework UiO-66: An
           effective catalyst for the selective oxidation of cyclopentene to
           glutaraldehyde
    • Abstract: Publication date: 15 July 2015
      Source:Microporous and Mesoporous Materials, Volume 211
      Author(s): Xin-Li Yang , Li-Ming Qiao , Wei-Lin Dai
      A heterogenous Zr-based metal organic framework (UiO-66) encapsulating phosphotungstic acid (HPWs) catalyst (HPWs@UiO-66), was prepared by a simple direct hydrothermal reaction of ZrCl4, terephthalic acid, and HPWs in DMF. The as-prepared novel material was very active as the catalyst for the selective oxidation of cyclopentene (CPE) to glutaraldehyde (GA) with environmentally benign hydrogen peroxide as the oxidant. The crystal structure and morphology of UiO-66 were well preserved after the incorporation of HPWs, as confirmed by X-ray diffraction (XRD), SEM, and TEM. Moreover, the XRD, N2 adsorption, and FT-IR analyses reveal that HPW components could stably exist in the nanocages of UiO-66. FT-IR-CO adsorption experiments indicated that additional Lewis acid sites were present in the HPWs@UiO-66 sample, which were essential to catalyze the selective oxidation of CPE to GA. A proper amount of HPWs and their high dispersion accounted for high catalytic activity. Almost complete conversion of CPE (∼94.8%) and high yield of GA (∼78.3%) were obtained using the 35 wt% HPWs@UiO-66 catalyst. Furthermore, HPW components hardly leached in the reaction solution, enabling the catalyst to be used for three reaction cycles without obvious deactivation.
      Graphical abstract image

      PubDate: 2015-03-17T11:05:36Z
       
  • Secondary growth of ZIF-8 films onto copper-based foils. Insight into
           surface interactions
    • Abstract: Publication date: 15 July 2015
      Source:Microporous and Mesoporous Materials, Volume 211
      Author(s): Rocío L. Papporello , Eduardo E. Miró , Juan M. Zamaro
      The film growth of the zeolitic imidazolate framework-8 on a copper-based substrate is reported for the first time in the literature. The growth mechanism on copper foils is analyzed, and it is demonstrated that during synthesis the development of the metal-organic framework (MOF) film is sensitive to the interactions produced between the support surface, the solvent and the reactants. In order to compare the surface interactions during synthesis, Fecralloy foils, porous alumina disks and macroporous cordierite monoliths are also analyzed. The physicochemical properties of the materials are evaluated by XRD, SEM, EPMA, AAS, DRIFT and XPS. In dimethylformamide-based media, no ZIF-8 film develops on the copper surface due to unfavorable interactions that make its growth non selective. At the same time, the formation of a dense ZnO layer is favored, this layer being promoted by decomposition products of the solvent and the zinc reagent. When water-based media are used, those interactions are modified thus avoiding the formation of oxide, but the growth kinetics of the ZIF-8 film is still low. On the other hand, when using mixtures based on methanol with the addition of acetate, continuous, uniform, and adherent ZIF-8 films can be obtained. Such films develop preferential crystallographic orientations in planes {200} and {110}, have thicknesses between 5 and 10 microns and good mechanical and thermal stability. The results obtained provide a platform for the obtention of ZIF-8 films on copper structures, which is relevant for the development of new structured catalysts based on MOFs.
      Graphical abstract image

      PubDate: 2015-03-17T11:05:36Z
       
  • Fe (II) segregation at a specific crystallographic site of fibrous
           erionite: A first step toward the understanding of the mechanisms
           inducing its carcinogenicity
    • Abstract: Publication date: 15 July 2015
      Source:Microporous and Mesoporous Materials, Volume 211
      Author(s): Paolo Ballirano , Alessandro Pacella , Carlo Cremisini , Elisa Nardi , Marzia Fantauzzi , Davide Atzei , Antonella Rossi , Georgia Cametti
      Two samples of fibrous erionite from different localities of Oregon, USA were suspended in FeCl2 solutions at different concentrations, at pH ca. 5, in anaerobic conditions. Comparison between released and acquired charges under the form of Fe confirms that erionite binds Fe (II) by ion exchange with the extra framework (EF) cations, mainly Na. The Fe (II) binding process exhibited by both studied samples here investigated indicates a direct correlation between the extent of the ion-exchange process and the Fe (II) concentration of the solution used for fibres incubation. In the sample from Rome no further Fe (II) acquisition was observed for concentrations exceeding 500 μM FeCl2. XPS investigation revealed that, when comparing surface and bulk composition of the samples, no Fe enrichment of the fibre surface was observed. Moreover, the location of Fe (II) within the erionite cage has been devised by combining chemical and structural data. Results highlight that, for both samples, Fe (II) is fixed at the Ca3 site being six-fold coordinated to water molecules. The occurrence of Fe (II) within the erionite cage causes a gradual migration of the other EF cations and in addition, induces a small rearrangement of the water molecules positions. It is worth mentioning that, in Fe-loaded zeolites at rather low Fe content, the Fe sites with very low nuclearity, located in well-defined crystallographic positions, represent the active sites for the formation of reactive oxygen species. Therefore, identification of segregation of Fe (II) at Ca3, which is coupled with the high surface area of erionite, provides very important information for the understanding of the molecular mechanism/s inducing its strong carcinogenicity.
      Graphical abstract image

      PubDate: 2015-03-17T11:05:36Z
       
  • Some considerations regarding the mesopore structure and order in MSU-3
           and MSU-F (organo)silicas
    • Abstract: Publication date: 15 July 2015
      Source:Microporous and Mesoporous Materials, Volume 211
      Author(s): Babak Fotoohi , Louis Mercier
      Development of mesoporous materials and specifically mesoporous silica was an advancement of that of microporous materials such as zeolites. Major advantages associated with mesopore nanostructures have largely depended on bigger pore size, high pore order and rather high flexibility in modification of the pore system. For this reason, large-pore and highly ordered mesoporous silica (e.g. SBA-15) were introduced taking advantage of co-polymer surfactants as structure directing agents, while pore size expansion was still extended toward making mesoporous silica foams. At the same time neutral cooperative self-assembly of silica precursors and non-ionic surfactants resulted in facile preparation of MSU-X family of mesoporous silica obtained in milder synthesis conditions. This research tries to bring new insights into the versatility of MSU-X preparations that would show highly ordered or engineered mesopore network. The mesostructural properties of MSU-3 and MSU-F materials subjected to hydrothermal processing and different functionalization were studied in detail with gas adsorption, TEM and XRD analyses. Use of different silica precursors and functionalizations brought differences in the mesopore structure. It was possible, in these syntheses, to obtain highly hexagonal mesopore order in the hybrid MSU-3 in a co-condensation synthesis with MPTMS in presence of inorganic silica precursor. On the other hand, during the course of silica foam (MSU-F) preparations, due to the effect of post-synthesis hydrothermal processing, considerable modification of the large mesopores brought the opportunity to achieve fully bimodal (both channel-like and mesocellular) pore morphologies in the material framework.
      Graphical abstract image

      PubDate: 2015-03-17T11:05:36Z
       
  • Polymerizable sol–gel precursor mediated synthesis of TiO2 supported
           zeolite-4A and its photodegradation of methylene blue
    • Abstract: Publication date: 15 July 2015
      Source:Microporous and Mesoporous Materials, Volume 211
      Author(s): Ravikiran Nagarjuna , Sounak Roy , Ramakrishnan Ganesan
      A polymerizable sol–gel method has been employed to synthesize tailored TiO2 supported zeolite-4A. The synthetic procedure was optimized by using FTIR, TGA and DSC to prepare various TiO2 loading ranging from 10 to 30 wt% on the support. The as-synthesized materials were characterized thoroughly with powder XRD, SEM, UV–Vis spectroscopy and BET surface area measurements. The characterization reveals that the polymerizable sol–gel approach yields highly dispersed nano-crystalline TiO2 on the zeolite-4A support. The tailored materials exhibited high rate of photocatalytic degradation of methylene blue at alkaline pH. The used catalysts were subjected to recyclability investigations, which demonstrated highly stable surface of these materials.
      Graphical abstract image

      PubDate: 2015-03-17T11:05:36Z
       
  • Facile synthesis of acid mesoporous fluoropolymer as water-tolerant
           catalyst for esterification
    • Abstract: Publication date: 15 July 2015
      Source:Microporous and Mesoporous Materials, Volume 211
      Author(s): Mengli He , Jun Xu , Zhong-Hua Ma , Hong Yuan , Jingzhong Ma
      Mesoporous fluoropolymers with excellent hydrophobicity and acidity (H-PDVB-x-SSFAI) were solvothermally prepared by radical polymerization of perfluoroalkyl sulfonyl imide and divinylbenzene. The formation of mesopores depended on the synergy effect between nano-CaCO3 porogen and watered solvothermal media. The amount of doped water, and reactant ratio as well, was responsible for the textural properties. The fluoropolymers catalyzed the esterification of long-chain fatty acids with ethanol affording the conversion of 95%, along with TOF of 30.5 h−1 (31.9 h−1 reported for H2SO4). The high efficiency was attributed to its excellent hydrophobicity, wettability for ethanol, and acidity. Stability trial evinced that the fluoropolymers were sufferable to 24 h water-boiling with 86% acid groups remained. These are promising recyclable fluoropolymers, maintaining fairly stable catalytic activity for esterification of acetic acid with pentanol at least 7 runs.
      Graphical abstract image

      PubDate: 2015-03-17T11:05:36Z
       
  • Stepwise structuring of the adsorbed layer modulates the physico-chemical
           properties of hybrid materials from phyllosilicates interacting with the
           μ-oxo Fe+3-phenanthroline complex
    • Abstract: Publication date: 15 July 2015
      Source:Microporous and Mesoporous Materials, Volume 211
      Author(s): Fabrizio Bernini , Elena Castellini , Daniele Malferrari , Marco Borsari , Maria Franca Brigatti
      The μ-oxo Fe+3-phenanthroline 1:1 complex [(OH2)3(Phen)FeOFe(Phen)(OH2)3]+4 (hereafter Fe+3Phen) was successfully immobilized on montmorillonite (Mt) and kaolinite (Kt) minerals. Adsorption data on both minerals described an adsorption isotherm of VI type and were successfully fitted using two independent Frumkin isotherms. The interaction between the complex and the minerals is strong and yields two stable hybrid materials: Kt–Fe+3Phen and Mt–Fe+3Phen. DR UV–Vis, elemental analysis, TGA-MSEGA, temperature-controlled XRPD techniques were used to characterize the structural properties of the hybrid materials. These investigations showed that the Fe+3Phen adsorption occurs stepwise via the formation of a bilayer structure. The first layer is the result of a cation exchange process involving the negative charges of the mineral, while the second one probably forms through stacking interaction and/or sulphate ions bridging. XRD measurements show that for Mt the interaction between the mineral and the complex occurs especially in the interlayer and the second layer formation is accompanied by a super-structuring of the interlayer that changes the thermal stability and physico-chemical properties of the composite material.
      Graphical abstract image

      PubDate: 2015-03-17T11:05:36Z
       
  • The remarkable effect of the preparation procedure on the catalytic
           activity of CoBEA zeolites in the Fischer–Tropsch synthesis
    • Abstract: Publication date: 15 July 2015
      Source:Microporous and Mesoporous Materials, Volume 211
      Author(s): Karolina A. Chalupka , Sandra Casale , Ewa Zurawicz , Jacek Rynkowski , Stanislaw Dzwigaj
      This work deals with the investigation of the influence of the preparation procedure and Co content on the activity of CoBEA zeolite in Fischer–Tropsch synthesis. For this purpose the Co-containing zeolites were prepared by a conventional wet impregnation (Co x AlBEA series) and a two-step postsynthesis method (Co x SiBEA series). Calcination at 500 °C, for 3 h in air and then reduction at 500 °C in flow of 95% H2–5% Ar stream of as prepared Co x AlBEA and Co x SiBEA zeolites led to obtain Red-C-Co x AlBEA and Red-C-Co x SiBEA catalysts with different properties in Fischer–Tropsch reaction. The most active catalysts were Red-C-Co10SiBEA and Red-C-Co20SiBEA with high CO conversion of 90–95% and selectivity towards liquid products of 85% containing C7–C18 n-alkanes, isoalkanes and small amount of olefins. In the case of Red-C-Co x AlBEA catalysts the CO conversion was of 68% and selectivity towards liquid products of 57%. The identified liquid products were mainly C7–C16 n-alkanes. Moreover, Red-C-Co x SiBEA catalysts demonstrated better stability and resistance to coke formation than Red-C-Co x AlBEA ones. It is probably related to higher dispersion of cobalt nanoparticles in Red-C-Co x SiBEA than in Red-C-Co x AlBEA catalysts and absence of strong Brønsted acidic sites in the former after removal of aluminum in the first step of two-step postsynthesis preparation procedure.
      Graphical abstract image

      PubDate: 2015-03-17T11:05:36Z
       
  • Computational screening of covalent organic frameworks for CH4/H2, CO2/H2
           and CO2/CH4 separations
    • Abstract: Publication date: 1 July 2015
      Source:Microporous and Mesoporous Materials, Volume 210
      Author(s): Minman Tong , Qingyuan Yang , Chongli Zhong
      A diverse set of 46 covalent organic frameworks (COFs) were collected to computationally predict their separation performance for three industrial gas mixtures, CH4/H2, CO2/H2 and CO2/CH4, using pressure swing adsorption (PSA) process. The results show that COFs outperform most commonly used zeolites and widely studied metal-organic frameworks (MOFs) in the separation of CH4/H2, while have a comparable performance in separating CO2/H2 and CO2/CH4. In addition, microscopic information that is instructive for developing more efficient COFs was obtained by analyzing the relationships between separation performance and framework structures. The results of this work provide useful information that can guide the future design of new COFs with improved performance, as well as demonstrate that COFs are very promising adsorbents in industrial gas separation applications and are worthy of further in-depth study toward practical applications.
      Graphical abstract image

      PubDate: 2015-03-12T18:21:28Z
       
  • Fabrication of hierarchical cabbage-like carbonaceous materials by
           one-step cobalt-assisted hydrothermal carbonization of furfural
    • Abstract: Publication date: 1 July 2015
      Source:Microporous and Mesoporous Materials, Volume 210
      Author(s): Xiujuan Chen , Zhiguo Li , Li Wei , Xiaoli Li , Siping Liu , Jiyou Gu
      In this study, 3D hierarchical cabbage-like carbonaceous materials (CCMs) have been fabricated by one-step hydrothermal carbonization of furfural in the presence of cobalt acetylacetonate under mild condition. The morphologies and structures of the CCMs could be well controlled by regulating the reaction conditions including reactant concentration, reaction temperature and time. It was revealed that the cobalt acted as a structure-directing agent during the formation of the cabbage-like structures, which induced the morphology evolution of the products from microspheres into hierarchical CCMs. The good electrochemical performance and well-loading of Pt nanoparticles on the surface of the CCMs further indicated that the CCMs have potential applications in electrochemical capacitors and heterogeneous catalysis.
      Graphical abstract image

      PubDate: 2015-03-12T18:21:28Z
       
  • Alkylation of phenols and acylation 2-methoxynaphthalene over SSZ-33,
           SSZ-35 and SSZ-42 zeolites
    • Abstract: Publication date: 1 July 2015
      Source:Microporous and Mesoporous Materials, Volume 210
      Author(s): Dana Vitvarová , Lenka Lupínková , Martin Kubů
      Zeolites with different framework topology (SSZ-33, SSZ-35 and SSZ-42) were investigated in alkylation of phenol, m-cresol and p-cresol, and acylation of 2-methoxynaphthalene. Their catalytic behavior was compared with commercial zeolites BEA, USY, MOR and ZSM-5. Borosilicates SSZ-33 and SSZ-42 were isomorphously substituted into aluminum form by low temperature hydrothermal treatment. The phenol conversions decreased in the order: BEA 91.9% ∼ SSZ-33 90.5% > MOR 58.0% > SSZ-35 38.0% > SSZ-42 22.6%. The selectivity to C-alkylated product 2-cyclohexylphenol prevailed over selectivity to 4-cyclohexylphenol and phenyl cyclohexyl ether almost for all tested catalysts. The selectivities to 2-cylcohexylphenol were as follows: SSZ-35 85% > BEA 67% > SSZ-33 42% > SSZ-42 35% (at conversion of cyclohexene = 20%). Zeolite SSZ-33 was quite effective catalyst in acylation of 2-methoxynaphthalene. The conversions of 2-methoxynaphthalene achieved over SSZ-33 zeolite were similar to that obtained over zeolite BEA. The selectivities to 2-acetyl-6-methoxynaphthalene achieved over zeolites BEA and SSZ-33 were in the range 48–63 % for both tested acylating agents.
      Graphical abstract image

      PubDate: 2015-03-12T18:21:28Z
       
  • Nanoporous gyroid TiO2 and SnO2 by melt infiltration of block copolymer
           templates
    • Abstract: Publication date: 1 July 2015
      Source:Microporous and Mesoporous Materials, Volume 210
      Author(s): Tao Li , Lars Schulte , Ole Hansen , Sokol Ndoni
      Fabrication of meso-porous metal oxide thin films with high surface area is a crucial requirement for numerous applications, such as catalysis, photovoltaics and electronics. Despite considerable progress in fabrication of three-dimensional metal oxide nanostructures, it is still quite challenging to manufacture highly ordered structures over a large area in a controlled way. The main objective of this study is to demonstrate fabrication of interconnected, crack-free and highly ordered ceramic films using a nano-porous polymer with gyroid morphology as template. Titanium tetraisopropoxide and tin chloride dihydrate are used as precursors for nanostructured TiO2 and SnO2, respectively. Complete precursor infiltration into the template and successful transformation into metal oxides can be achieved by rational tuning of the template chemistry. As a result, thin films of nanostructured metal oxides with gyroid morphology, such as titania and tin dioxide, are created and thoroughly characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersive analysis, x-ray diffraction and Brunauer–Emmett–Teller analysis.
      Graphical abstract image

      PubDate: 2015-03-12T18:21:28Z
       
  • A statistical approach to control porosity in silica-doped alumina
           supports
    • Abstract: Publication date: 1 July 2015
      Source:Microporous and Mesoporous Materials, Volume 210
      Author(s): Maryam Khosravi Mardkhe , John Lawson , Baiyu Huang , Erika D. Handly , Brian F. Woodfield
      A split-plot statistical design was used to identify and systematically study the effects of synthesis variables on the pore properties of silica-doped alumina (SDA) from data obtained for 96 samples. Seven preparation variables (mixing method, time, environment; calcination ramp rate; drying temperature, environment; and alcohol concentration) were found to alter surface area, pore volume, and pore diameter over wide ranges, i.e. factors of 1.8, 1.4, and 3.3, respectively. Large pore diameters (>40 nm) were obtained by addition of excess alcohol. Large pore volumes (>2 cm3/g) were obtained by drying before calcination at 100 °C for 24 h. High surface area (>400 m2/g) was obtained when no alcohol was used. The gamma phase of all SDA samples was thermally stable to 1200 °C. Using split-plot statistical analysis of the experimental data, models were developed which predict quantitatively the relationship between surface properties (surface area, pore volume and pore diameters) and synthesis parameters. Based on these models, optimal conditions to produce SDA samples with large (40–60 nm) or medium (16–19 nm) pore diameters, high surface area (>250 m2/g) and large pore volume (>1 cm3/g) are quantitatively predicted. Model predictions of optimal conditions were accurately confirmed by follow-up experiments. The chemistry underlying these predictions is also addressed.
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      PubDate: 2015-03-12T18:21:28Z
       
  • Competitive adsorption of lysozyme and myoglobin on mesostructured
           cellular foam silica
    • Abstract: Publication date: 1 July 2015
      Source:Microporous and Mesoporous Materials, Volume 210
      Author(s): Amina Darwish , Taylor Robie , Rebecca J. Desch , Stephen W. Thiel
      A model of multicomponent multilayer adsorption has been developed to describe the simultaneous adsorption of lysozyme (14.3 kDa, pI = 11.35) and myoglobin (17.6 kDa, pI = 7.2) on mesostructured cellular foam (MCF) silica in 0.02 M potassium phosphate buffer at pH 7 and 25 °C. The mechanism of adsorption was proposed based on batch adsorption isotherms and flow microcalorimetry (FMC) traces for the enthalpy of adsorption. Thermodynamic derivations of Guggenheim–Anderson–deBoer (GAB) and Langmuir models were used to develop the model based on the proposed mechanism. Regression analysis demonstrated the effect of each of the proposed mechanistic equations.
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      PubDate: 2015-03-09T03:21:51Z
       
  • Postsynthetic modification of copper terephthalate metal-organic
           frameworks and their new application in preparation of samples containing
           heavy metal ions
    • Abstract: Publication date: 1 July 2015
      Source:Microporous and Mesoporous Materials, Volume 210
      Author(s): Yanzi Wu , Guanhong Xu , Wei Liu , Jing Yang , Fangdi Wei , Lei Li , Wen Zhang , Qin Hu
      In this paper, a novel thiol-functionalized porous metal-organic frameworks (MOFs), namely thiol-functionalized [Cu4O(BDC)]n (BDC = Terephthalic acid), was synthesized. The successful modification was certified by Fourier transform infrared spectroscopy and X-ray powder diffraction. The modified MOFs were further characterized by scanning electron microscopy and thermogravimetric measurements. The adsorption of the modified MOFs for both common and heavy metals was investigated. The modified MOFs showed remarkable and selective adsorption for four heavy metals (Hg2+, Cr6+, Pb2+, Cd2+), especially for Hg2+. The dynamic and static adsorption tests showed that the modified MOFs exhibited high adsorption capacity and selectivity for Hg2+, and offered a fast kinetics for the adsorption of Hg2+. The as-synthesized modified MOFs were successfully used as adsorbents to selectively enrich the above four heavy metals in preparation of a tea sample. The results indicate that functionalized MOFs by postsynthetic modification have a promising potential in preparation of samples containing heavy metal ions.
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      PubDate: 2015-03-09T03:21:51Z
       
  • Ionothermal syntheses of transition-metal-substituted aluminophosphate
           molecular sieves in the presence of tetraalkylammonium hydroxides
    • Abstract: Publication date: 1 July 2015
      Source:Microporous and Mesoporous Materials, Volume 210
      Author(s): Dawei Li , Yunpeng Xu , Huaijun Ma , Renshun Xu , Yasong Wang , Hao Liu , Bingchun Wang , Zhijian Tian
      Transition-metal-substituted aluminophosphate (MeAPO) molecular sieves with SOD and AEI framework types have been synthesized ionothermally in the ionic liquid 1-ethyl-3-methylimidazolium bromide with adding four tetraalkylammonium hydroxides, including tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide. Detailed synthetic investigation shows that the nature and concentration of the tetraalkylammonium hydroxide, the Me/Al ratio in the reaction mixture and the metal sources greatly influence the phase selectivity of the reaction. The products have been characterized by PXRD, SEM, ICP, CHN, UV–Vis spectroscopy, 13C, 27Al and 31P MAS NMR, and TG. The results reveal that the tetraalkylammonium cations compete with the ionic liquid cations to act as the structure directing agent. The templating ability of the tetraalkylammonium cations and the ionic liquid cations is closely related to their charge densities.
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      PubDate: 2015-03-09T03:21:51Z
       
  • Effect of pore structure on adsorption behavior of ibuprofen by magnetic
           anion exchange resins
    • Abstract: Publication date: 1 July 2015
      Source:Microporous and Mesoporous Materials, Volume 210
      Author(s): Jun Wang , Haibo Li , Chendong Shuang , Aimin Li , Cheng Wang , Yu Huang
      A series of magnetic anion exchange resins (ND-1, ND-2 and ND-3) with different pore structure were prepared for ibuprofen (IBU) adsorption by using different amount of cyclohexanol as porogen in this work. For adsorption kinetics, resins with larger pore structure showed faster adsorption rates and higher equilibrium adsorption capacities because the internal diffusion process was facilitated by the increase of pore diameter and pore volume. As for adsorption isotherms, the experimental data was better fitted by Freundlich model especially for the resins with broader pores, suggesting that heterogeneous interactions took place in pores. The counter ion released by resin was measured, and ratios of equilibrium adsorption capacity to the counter ion were between 1.22 and 1.56, which confirmed that adsorption process was predominantly attributed to ion exchange while other interactions also existed. Hence, the co-existent anion reduced the adsorption amount of IBU onto resin by competing adsorption in ion exchange process, and the optimal pH ranged from 6 to 8. Resins with more open structure showed better regeneration abilities, of which the adsorption amounts witnessed no significant decrease during 7 circles of use, indicating the advantages of larger pore canal in the adsorption and regeneration behavior.
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      PubDate: 2015-03-09T03:21:51Z
       
  • Fabrication of high-surface area nanoporous SiOC materials using
           pre-ceramic polymer blends and a sacrificial template
    • Abstract: Publication date: 1 July 2015
      Source:Microporous and Mesoporous Materials, Volume 210
      Author(s): Xiaojie Yan , Theodore T. Tsotsis , Muhammad Sahimi
      We report the fabrication of silicon oxycarbide (SiOC) ceramics with high surface area and porosity and a hierarchical pore structure. They have been synthesized using polymer blends that consist of allyl hydridopolycarbosilane (AHPCS) and hydridopolycarbosilane (HPCS) as the precursors. Layered double hydroxides (LDHs), modified by sodium dodecylbenzenesulfonate (SDBS), a common surfactant, are used as a sacrificial template, and a simple impregnation technique is employed to enable the polymer precursor to penetrate into the LDH structure. Various characterization methods, such as XRD, XPS, and SEM-EDX, are used to verify that the ceramics that are produced are SiOC materials. A key aspect of the fabrication process is the use of pre-ceramic polymer blends that are capable of producing ceramics with an interconnected porous space. Air calcination of the as-prepared SiOC ceramic removes any free carbon that is present, but preserves the pore structure of the material. The SEM images indicate that the materials' internal pore structure consists of well-aligned, slit-like pores. Nitrogen sorption measurements demonstrate that the material fabricated from polymer blend AHPCS/HPCS = 2:1 has surface areas as high as 811.7 m2/g, total pore volume as large as 0.80 cm3/g with considerable fractions of micro- and mesopores. The synthesis method that we have developed uses low-cost pre-ceramic polymer precursors and templates and generates porous SiOC ceramics with high surface area, interconnected pore space with a multi-modal pore size distribution, and high-temperature stability. As such, the technique may be considered as a convenient and cost-effective approach for the fabrication of a wide class of porous materials for such applications as catalysis, gas adsorption/separation under harsh conditions, and biomedical device uses, etc.
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      PubDate: 2015-03-09T03:21:51Z
       
  • On the formation and accessibility of gold nanoparticles confined in
           SBA-15 mesoporous molecular sieve
    • Abstract: Publication date: 1 July 2015
      Source:Microporous and Mesoporous Materials, Volume 210
      Author(s): Bianca Faceto , Erico Teixeira-Neto , Heloise O. Pastore , Cristiano L.P. Oliveira , Angela A. Teixeira-Neto
      Mesoporous molecular sieves containing metal nanoparticles inside their pores have been lately studied as promising oxidation catalysts. Articles usually claim that confined particles are less prone to sintering and metal leaching. Furthermore, the pores limit nanoparticle growth during the process of preparation of the catalyst. In this work, we addressed some questions that are still to be answered, such as: how are the metal nanoparticles formed within the pores? Are these particles accessible to the organic molecules in catalytic reactions? For this purpose, SBA-15 samples containing Au nanoparticles were prepared and characterized. FTIR, TG/MS, XRD and XPS gave some insights on the formation of Au nanoparticles, while N2 adsorption and SAXS were useful to address the accessibility question. It was observed that Au-SBA-15, in spite of having a pore size distribution similar of that of SBA-15, has a lower pore volume and half of the surface area. SAXS experimental data was interpreted with the aid of a theoretical model, and it was possible to demonstrate that the presence of metal induced changes on the lattice parameter and pore dimensions of SBA-15. The results strongly indicate that the pores were filled. TEM images reveal the presence of very small Au nanoparticles inside the pores of the material, and also larger particles on its external walls. Au-SBA-15 is thus a material that is very dissimilar from its precursor, pure-silica SBA-15, and so its adsorption properties must be carefully evaluated.
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      PubDate: 2015-03-09T03:21:51Z
       
  • Effect of water treatment on Sn-BEA zeolite: Origin of 960 cm−1
           FTIR peak
    • Abstract: Publication date: 1 July 2015
      Source:Microporous and Mesoporous Materials, Volume 210
      Author(s): Timothy D. Courtney , Chun-Chih Chang , Raymond J. Gorte , Raul F. Lobo , Wei Fan , Vladimiros Nikolakis
      The correlation of the ∼960 cm−1 IR absorption band, frequently observed in Sn-BEA zeolite, to the incorporation of Sn in the zeolite framework has been investigated. IR and NMR spectra of freshly calcined and water treated zeolites combined with first principle calculations indicate that the 960 cm−1 band is not a vibration involving Sn but rather a result of isolated internal silanol groups. Thermogravimetric analysis and temperature-programmed desorption showed the silanol groups condense to form water at temperatures between 400 and 700 °C. These silanol groups form slowly at mild relative humidity (∼30–40%) and 25 °C, but in less than an hour at 98 °C in liquid water: they are expected to form in the course of an aqueous phase reaction. The water uptake observed following a one-hour liquid water treatment is 1.2 wt% in Sn-BEA with Si/Sn = 125, equal to 4–5 water molecules per Sn or 1 water molecule per 40 Si, too high for all of it to be directly linked to interaction with Sn atoms. Instead this water uptake can be explained by a site that can be hydroxylated at relatively low temperatures and dehydrated at temperatures typically used for zeolite calcination.
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      PubDate: 2015-03-05T22:07:14Z
       
  • Editorial Board
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208




      PubDate: 2015-03-05T22:07:14Z
       
  • Tailoring p-xylene selectivity in toluene methylation on medium pore-size
           zeolites
    • Abstract: Publication date: 1 July 2015
      Source:Microporous and Mesoporous Materials, Volume 210
      Author(s): John H. Ahn , Robin Kolvenbach , Oliver Y. Gutiérrez , Sulaiman S. Al-Khattaf , Andreas Jentys , Johannes A. Lercher
      The p-xylene selectivity in toluene methylation was investigated over medium pore-size zeolites (H-ZSM5, H-ZSM11 and H-NU10) as well as after deposition of tetraethyl orthosilicate on the surface, isomorphous substitution of aluminum by iron and variation the crystal size. Higher reaction temperatures consistently resulted in higher p-xylene selectivity in the three reaction pathways for the formation of p-xylene during toluene methylation, i.e., methylation of toluene, isomerization of xylenes, further methylation and subsequent formation of xylenes after dealkylation of light hydrocarbons. The increased selectivity is attributed to the accumulation of slowly diffusing reaction products in the zeolite pores. Thus, the isomerization of m- and o-xylenes, as well as dealkylation of higher alkylated products influenced the xylene selectivity most strongly at high temperatures, while the intrinsic selectivity of the toluene alkylation dominates at lower reaction temperatures due to the absence of transport restrictions.
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      PubDate: 2015-03-05T22:07:14Z
       
  • Adsorption performance and mechanism of perchloroethylene on a novel
           nano composite β-FeOOH-AC
    • Abstract: Publication date: 1 July 2015
      Source:Microporous and Mesoporous Materials, Volume 210
      Author(s): Yubin Zeng , Ziyang Zeng , Tingyu Ju , Fan Zhang
      Akaganeite-activated carbon (β-FeOOH-AC) nano composite was prepared firstly and characterized. β-FeOOH-AC was used in the removing perchloroethylene (PCE) from water. The adsorption performance and mechanism of PCE from water by β-FeOOH-AC is investigated through batch experiments including kinetics, thermodynamics and isothermal adsorption models. The results show that the PCE removal achieves 97.83% when the initial PCE concentration is 100 mg/L and sorbent dosage is 8 g/L at temperature 298 K. The kinetic data prove a closer fit to the pseudo-second order model. The isotherm data can be fit with Langmuir and Freundlich isothermal adsorption models. Additionally, the thermodynamic analysis indicates PCE adsorption on β-FeOOH-AC is a spontaneous, endothermic, single and multi-layer combined physical adsorption process, and β-FeOOH-AC has a strong PCE adsorption affinity. The excellent adsorption performance and low cost of the β-FeOOH-AC can be considered as one of the effective options to remove PCE from contaminated water.
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      PubDate: 2015-03-05T22:07:14Z
       
  • Hydrogen storage in bulk graphene-related materials
    • Abstract: Publication date: 1 July 2015
      Source:Microporous and Mesoporous Materials, Volume 210
      Author(s): Alexey G. Klechikov , Guillaume Mercier , Pilar Merino , Santiago Blanco , César Merino , Alexandr V. Talyzin
      Hydrogen sorption properties of graphene-related materials were studied by gravimetric and volumetric methods at 293 K and 77 K. Rapid thermal exfoliation of different types of graphite oxide (GO) precursors yielded samples with maximal surface areas up to 850 m2/g, whereas surface areas up to 2300 m2/g were achieved by post-exfoliation activation treatments. Therefore, hydrogen storage parameters of graphene materials could be evaluated in a broad range of surface areas. The H2 uptake vs surface area trend revealed in this study shows that hydrogen storage by graphene materials do not exceed 1 Wt% at 120 Bar H2 at ambient temperatures. Linear increase of hydrogen adsorption vs surface area was observed at 77 K with maximal observed value of ∼5 Wt% for 2300 m2/g sample. It can be concluded that bulk graphene samples obtained using graphite oxide exfoliation and activation follow standard for other nanostructured carbons hydrogen uptake trends and do not demonstrate superior hydrogen storage parameters reported in several earlier studies. Nevertheless, graphene remains to be one of the best materials for physisorption of hydrogen, especially at low temperatures.
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      PubDate: 2015-03-05T22:07:14Z
       
  • A combined theoretical and experimental analysis on transient
           breakthroughs of C2H6/C2H4 in fixed beds packed with ZIF-7
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): De-Li Chen , Ningwei Wang , Chunhui Xu , Gaomei Tu , Weidong Zhu , Rajamani Krishna
      The selective separation of C2H6/C2H4 mixtures can be achieved by the zeolitic imidazolate framework ZIF-7, which is a well-known flexible microporous material due to its gate-opening effect in response to external stimuli such as pressure and temperature. Transient breakthrough experiments with C2H6/C2H4 mixtures were carried out at varying pressure and temperature conditions to confirm the potential application of ZIF-7 to selectively adsorb the saturated alkane and reject the unsaturated alkene in the gas phase during the adsorption cycle. Transient breakthrough simulations, including the influence of intra-crystalline diffusion, were compared with the experimental breakthroughs. The assumption of negligible diffusional limitations is able to capture the essential characteristics of the experimental breakthroughs. With the breakthroughs from both experiments and simulations, the adsorbed amounts of C2H6 and C2H4 in ZIF-7 were calculated to estimate the separation selectivity, which is in reasonable agreement with ideal adsorbed solution theory calculations. The derived isosteric heats of adsorption for both adsorbates are compared and used to explain the adsorption selectivity for C2H6 over C2H4 in ZIF-7. The good agreement between experiments and simulations verifies that the simulation methodology employed in the current study is a valuable and efficient tool for modeling the separation performance of C2H6/C2H4 mixtures in ZIF-7.
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      PubDate: 2015-02-28T16:41:24Z
       
  • ZSM-5 and ferrierite synthesized by magadiite conversion method in 1,
           6-hexamethylenediamine system
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Yu Wang , Tianming Lv , Huilong Wang , Yalei Zhao , Changgong Meng , Hao Liu
      ZSM-5 and ferrierite have been successfully synthesized by magadiite conversion method using 1, 6-hexamethylenediamine (HMD) as structure directing agent. The binary crystallization phase diagram was obtained by various reactant ratios of H2O/SiO2 and SiO2/Al2O3 and the regular phase transformations were also demonstrated. The optimized reactant HMD/SiO2 ratio was 0.6. The high crystalline ZSM-5 was composed of coffin-shaped crystallite with length of 4 μm where as ferrierite exhibited plate-like crystallite having a diameter of 8 μm. The 13C MAS NMR spectra revealed that the HMD which can be used as a structure directing agent in the conversion process was held tenaciously inside the pores of ZSM-5 and ferrierite. The formula of as-obtained ZSM-5 and ferrierite could be K2.1(C6H16N2)4.2(H2O)16.9H8.4 [Si85.5Al10.5O192] and K2.1(C6H16N2)0.9(H2O)6.4H2.2 [Si31.7Al4.3O72] respectively based on the compositional analysis. More over the structure of prepared ZSM-5 and ferrierite were collapsed when the temperature rose up to 1200 °C and 1100 °C respectively; both are exceptionally stable towards strong acid.
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      PubDate: 2015-02-28T16:41:24Z
       
  • Prediction of gas storage capacities in metal organic frameworks using
           artificial neural network
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Zeynep Yıldız , Harun Uzun
      In this study, artificial neural network was developed to forecast adsorption capacity of hydrogen gas in metal organic frameworks. Surface area, adsorption enthalpy, temperature and pressure were selected as input parameters. Hydrogen storage capacities of MOFs were computed using these four parameters. An artificial neural network was used to model the adsorption process. The prediction results were remarkably agreed with the experimental data.
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      PubDate: 2015-02-28T16:41:24Z
       
  • Thermal transformation of Cs-clinoptilolite to CsAlSi5O12
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Antonio Brundu , Guido Cerri
      In this study we have investigated the protocol to produce CsAlSi5O12 (CAS), a potential host for radioactive cesium, starting from clinoptilolite, a natural zeolite employed in cesium decontamination. A clinoptilolite-rich rock sampled in Sardinia (Italy) has been subjected to a beneficiation process, to obtain a powder with a higher zeolite content. The enriched material (90 wt% clinoptilolite) has been previously Na-, then Cs-exchanged. Both forms have been analyzed by ICP-AES and ICP-MS. Thermal treatments of 2 hours between 800 and 1250 °C have been performed on different aliquots of the Cs-exchanged material. Samples heated at T ≥ 1150 °C are composed basically only by CAS, as determined by XRD analyses, and their high crystallinity has been also confirmed by SEM observations. Ideally, the nucleation of CAS follows the reaction Cs6Al6Si30O72·nH2O → nH2O↑ + 6CsAlSi5O12. DTA analyses indicate that the transformation has occurred at 1145 °C. TG analyses, coupled with XRD data, lead to exclude a cesium volatilization during the synthesis of CAS.
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      PubDate: 2015-02-28T16:41:24Z
       
  • Calculation of microchannel parameters in aluminophosphate zeolites
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): I.V. Grenev , V.Yu. Gavrilov
      Adsorption interaction of molecular hydrogen with framework atoms of aluminophosphate zeolites AlPO-5, -11, -8 and -36 were analyzed using a representative fragment of the structure with the volume about 32 nm3. Isopotential surfaces of the interaction between molecules were calculated. Isopotential surfaces with zero adsorption potential outline the shape of microchannels. Theoretical values of the zeolite microchannel volumes were calculated. Places for preferential localization of the sorbate molecules in the zeolite structure (places with the lowest adsorption potential) were determined for the Henry adsorption isotherm range. Calculated and experimental values of Henry constants for hydrogen adsorption at 77 K were compared.
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      PubDate: 2015-02-28T16:41:24Z
       
  • Stability of UiO-66 under acidic treatment: Opportunities and limitations
           for post-synthetic modifications
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): C.G. Piscopo , A. Polyzoidis , M. Schwarzer , S. Loebbecke
      In chemical and functional modification of Metal-organic frameworks (MOFs), preserving their structure and topology is a challenging goal, due to the high sensitivity of these materials to moisture, chemical and thermal treatments. The porous material UiO-66 is one of the most stable MOFs, retaining its properties under a relative wide range of chemical and physical conditions. The unique robustness of UiO-66 derives from the 12-coordinated Zr6-clusters that constitute the framework. Nevertheless, variation on the synthetic pathways may lead to different coordination of the Zirconium sites, influencing the stability and activity of this MOF during applications such as catalysis. Herein a survey of the stability of UiO-66 under acidic treatment is presented. The porous metal-organic framework has been synthesized according to two alternative procedures; these two solid materials and a commercially available UiO-66 sample have been suspended in several aqueous acids and have been characterized after the impregnation tests. These results lead to a better understanding of the matter of acidic stability of the selected MOF, clarifying whether it is possible to enhance its stability by choosing a dedicated synthesis route and providing essential information in order to proceed with a large number of post-synthetic modifications. Among these reactions, the sulfonation of UiO-66, which is an example of outstanding importance, has been investigated. The stability of UiO-66 versus mineral acids has been confirmed; however this MOF does not tolerate the use of electrophilic cationic species.
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      PubDate: 2015-02-28T16:41:24Z
       
  • Promotion of phosphoester hydrolysis by the ZrIV-based metal-organic
           framework UiO-67
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Patrique Nunes , Ana C. Gomes , Martyn Pillinger , Isabel S. Gonçalves , Marta Abrantes
      The ZrIV-based metal-organic framework (MOF) UiO-67 has been examined as a promoter of the hydrolysis of phosphoester bonds by using sodium para-nitrophenylphosphate (pNPP) as a model substrate. The reactions were followed by 1H NMR spectroscopy and performed under mild conditions using 2–100 mol% of the MOF relative to pNPP. All of the systems studied promoted the hydrolysis of pNPP to give para-nitrophenol (pNPh) and inorganic phosphate. A reaction half-life of ca. 30min was achieved using 17 mol% of UiO-67 at 55 °C and 30 mol% at ambient temperature; ≥98% removal of pNPP was reached within 1 h for both reaction temperatures. 1H NMR spectra of the reaction solutions, together with powder X-ray diffraction, FT-IR spectroscopy and solid-state NMR data for the recovered MOF, revealed that (i) pNPP was encapsulated and then converted to pNPh within the cavities of UiO-67, (ii) both pNPh and inorganic phosphate were retained in the solid promoter, and (iii) the MOF suffered partial structural breakdown into the components Zr6O4(OH)4 and 4,4′-biphenyldicarboxylate, with partial release of the latter into solution. These structural changes eventually compromized the recyclability of the promoter, although the material could be recovered and reused in a second cycle without loss of activity.
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      PubDate: 2015-02-28T16:41:24Z
       
  • Multi-scale characterization of porosity in Boom Clay (HADES-level, Mol,
           Belgium) using a combination of X-ray μ-CT, 2D BIB-SEM and FIB-SEM
           tomography
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Susanne Hemes , Guillaume Desbois , Janos L. Urai , Birgit Schröppel , Jens-Oliver Schwarz
      The Oligocene age Boom Clay is a potential host material for radioactive waste disposal in Belgium. To better understand the physical basis of transport mechanisms of radionuclides, we aim to characterize the pore space and its connectivity at nm-scale in 3D. In the present study, X-ray μ-CT and FIB-SEM (focused ion beam scanning electron microscopy) tomography were combined, to investigate the 3D pore space of a Boom Clay sample from the Mol-1 borehole (depth corresponding to the level of the HADES-URF – ‘high activity disposal experimental site underground research facility’) at the Mol–Dessel research site for radioactive waste disposal (Belgium). BIB-SEM (broad ion beam scanning electron microscopy) was used to bridge the gap in resolutions between X-ray μ-CT and FIB-SEM and to optimize the selection of a relevant spot for FIB-SEM. Pore network extraction (PNE) modeling (Dong and Blunt, 2009 [1]) was used to simplify the results into a set of pore bodies and pore throats, which are suitable for a statistical description. Resulting pore-size distributions are interpreted to be power-law distributed over ∼6 orders of magnitude, showing the scale-invariance of the pore space. We present a conceptual model of the 3D pore network in Boom Clay. The extracted 3D pore network model can be used to estimate transport properties – in digital rock models.
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      PubDate: 2015-02-28T16:41:24Z
       
  • Porous graphitic carbon materials prepared from cornstarch with the
           assistance of microwave irradiation
    • Abstract: Publication date: 1 July 2015
      Source:Microporous and Mesoporous Materials, Volume 210
      Author(s): Hong Lei , Yuhao Wang , Jichuan Huo
      Porous graphitic carbon materials (PGCs) have attracted great interest because of their properties shown in fields such as catalyst supports, electrochemical double layer capacitors, Li-ion batteries, etc. Biomass is a promising resource to produce PGCs, as it is cheap, eco-friendly and renewable. Using cornstarch as raw material, two PGCs (PGC-1 and PGC-2) were prepared by combining microwave-assisted catalytic graphitization and chemical activation. PGC-1 was made from new gelatinized starch and the other (PGC-2) from retrograded starch. The former was mainly composed of graphitic nanocoils. The latter, on the other hand, was more likely to be a product of activated loose packing carbonaceous sheets. Narrowly distributed hierarchical pores were observed in the PGCs. Both of the PGCs were partly graphitized and had large surface areas (353 m2/g for PGC-1 and 686 m2/g for PCG-2). Cyclic voltammetry and electrochemical impedance spectroscopy test showed that they had good capacitive property.
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      PubDate: 2015-02-28T16:41:24Z
       
  • CO2 sorption onto silica mesoporous materials made from nonionic
           surfactants
    • Abstract: Publication date: 1 July 2015
      Source:Microporous and Mesoporous Materials, Volume 210
      Author(s): Nabila Chalal , Hasna Bouhali , Hadj Hamaizi , Bénédicte Lebeau , Abdelkader Bengueddach
      Spherical mesoporous silica particles were successfully prepared by using non-ionic amphiphilic di-block co-polymers CnH2n+1-(EO)x-OH as templates and tetraethylorthosilicate (TEOS) as silica precursor. The synthesized mesoporous silica materials were characterized by X-ray diffraction (XRD), N2 adsorption–desorption and scanning electron microscopy (SEM) techniques. CO2 adsorption at 273 K was evaluated by a volumetric method, and the CO2 sorption behavior was described by applying both Langmuir and Freundlich equations. Results indicate a high adsorption capacity of CO2 (5–9 mmol/g), depending essentially on the porous texture of the materials. An adsorption kinetic model was used to describe the adsorption of CO2 over template-free mesoporous siliceous materials. A good agreement with experimental data was found.
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      PubDate: 2015-02-28T16:41:24Z
       
  • Preparation of hierarchical porous biomorphic carbide-derived carbon by
           polycarbosilane impregnation of wood
    • Abstract: Publication date: 1 July 2015
      Source:Microporous and Mesoporous Materials, Volume 210
      Author(s): Marion Adam , Martin Oschatz , Winfried Nickel , Stefan Kaskel
      Biomorphic carbide-derived carbon (CDC) materials with hierarchical pore structure are prepared by polycarbosilane impregnation of carbonized wood monoliths followed by subsequent pyrolysis and high-temperature chlorine treatment. Hierarchical pore structures are generated with combined macropores from the original cell structure of the wood and micro-/mesopores, investigated by scattering electron microscopy and nitrogen physisorption, respectively. The influence of polycarbosilane solutions concentration (20–100 wt.%), impregnation time (12–96h), and impregnation cycle number (1–3 times) on the mass gain during impregnation as well as specific surface area and nanopore volume of resulting CDCs is studied. Increasing concentration, time, and number of impregnation cycles lead to higher amount of infiltrated polymer in the wood monolith resulting in higher specific surface areas up to 940m2/g for the resulting CDCs. A linear increase of specific surface area as well as micro- and total pore volume with increasing mass gain takes place for all samples, independent of the impregnation conditions.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • Structural characterization of various alkali cation forms of synthetic
           aluminosilicate natrolites
    • Abstract: Publication date: 1 July 2015
      Source:Microporous and Mesoporous Materials, Volume 210
      Author(s): Jiho Shin , Deu S. Bhange , Min Bum Park , Suk Bong Hong
      The structures of the Na+, K+, Rb+, and Cs+ forms of PST-3 and PST-4, two synthetic aluminosilicate natrolite zeolites with almost completely disordered and ordered distributions of framework Si and Al atoms, respectively, in both hydrated and dehydrated states have been determined using synchrotron powder X-ray diffraction and Rietveld analyses. It was found that the trivalent tetrahedral atom (T-atom) content, as well as the type of extraframework alkali metal cations and the hydration state, is a more important factor governing the framework flexibility of this family of small-pore zeolites than the T-atom distribution.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • Synthesis and characterization of ordered mesoporous silica membrane: Role
           of porous support and gas permeation study
    • Abstract: Publication date: 1 July 2015
      Source:Microporous and Mesoporous Materials, Volume 210
      Author(s): Sanjib Barma , Bishnupada Mandal
      In this work, the supported silica membranes were synthesized on various self-made symmetrical α-alumina supports having different pore sizes by spin coating method. The final synthesized membranes were further characterized by XRD, FESEM and FTIR analysis. Gas separation properties of the resultant supported ordered mesoporous silica membranes were evaluated by single gas permeation experiments. The results showed that the lower pore sized α-alumina supports can effectively reduce the surface defects of the silica layer and enhance the gas permeation properties of the supported silica membranes. The orders of the silica structure were also improved by reducing the pore size of the α-alumina supports. Steady-state single gas permeation using CO2, Ar, He and N2 gases showed Knudsen diffusion mechanism for the membrane synthesized on the α-alumina support having lowest pore size of ∼0.09 μm. The other membranes having higher pore sized supports obeyed both Knudsen as well as viscous diffusion mechanisms. In addition, mixed gas permeation (20% CO2 and 80% N2) studies were carried out using amino functionalized mesoporous silica membrane.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • Nitrogen and oxygen co-doped microporous carbons derived from
           the leaves of Euonymus japonicas as high performance supercapacitor
           electrode material
    • Abstract: Publication date: 1 July 2015
      Source:Microporous and Mesoporous Materials, Volume 210
      Author(s): Lihua Zhu , Qiuming Gao , Yanli Tan , Weiqian Tian , Jiandong Xu , Kai Yang , Chunxiao Yang
      Bio-inspired nitrogen and oxygen heteroatom-doped porous carbons are prepared by facile pyrolysis of leaves of Euonymus japonicas (LEJ) with KOH activation. The pore textures of the carbons derived from LEJ (LEJCs) have been well controlled by adjusting the activation temperature. The obtained LEJCs possess large specific surface areas between 613 and 2071 m2 g−1 and moderate pore volumes of 0.281–0.872 cm3 g−1 with high micropore volume ratio of 74–96% and pore size distributions in the range of 0.5–2 nm. The optimized LEJC sample has 4.0 wt% N and 7.3 wt% O heteroatom-doped two-dimensional microporous structure as well as suitable specific surface area of 1268 m2 g−1 and pore volumes of 0.486 cm3 g−1 with the highest micropore volume ratio of 96% and main pore size distribution at 0.55 nm. The optimized LEJC material combining double layer and Faradaic redox electrochemical capacitance contributions, exhibits the max specific capacitance of 303 F g−1 at 0.2 A g−1, and 87% of the capacitance (264 F g−1) may be preserved when the current density increases to 40 A g−1 in 6 M KOH aqueous electrolyte. A high cycle stability with 80% capacitance retention has been observed after 5000 charge–discharge cycles at 5 A g−1. The max energy density of 15.2 Wh kg−1 has been gotten at the power density of 60.3 W kg−1, and a good energy density of 5.0 Wh kg−1 can be found at the high power density of 8.6 kW kg−1 in 6 M KOH.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • Rapid synthesis of faujasite/polyethersulfone composite membrane and
           application for CO2/N2 separation
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Bo Wang , Chenhu Sun , Yanzuo Li , Lin Zhao , W.S. Winston Ho , Prabir K. Dutta
      Rapid growth of faujasitic membranes on polyethersulfone support was investigated. The membrane growth occurred in a novel zeolite reactor, where the extent of supersaturation of the synthesis gel 8.5 Na2O: 1 Al2O3: 10.9 SiO2: 487H2O was controlled by removal of water from the reaction system. The gel remaining after removal of half the water from the reaction was isolated and used as a coating on the polymer support. Along with this reactive gel, coating of a uniform film of nanozeolite seed deposition on the porous polymer support was also investigated. Eight variations of the gel-seed combinations were examined for membrane growth. The optimal membrane synthesis condition was defined as coating of the PES support by a nanozeolite seed layer of 250–300 nm thickness, and then introduction into the reactor after water is removed, and continuing the reflux process with reintroduction of the water for another hour. Further characterization included X-ray diffraction, optical microscopy and detailed scanning electron microscopy. Leak test of a dye through the membrane and the mechanical stability of the membrane via a tape test were performed. The transport properties of these membranes for CO2/N2 separation were evaluated. There were three ways the membrane samples were prepared and handled for transport measurements. Prior to transport measurements, all samples were covered with PDMS. Initial attempts placed the seeded PES support into the growth reactor. These samples all exhibited poor transport properties with CO2/N2 selectivities less than 10. For the second group, the seeded PES supports were placed in a holder that ensured flatness during the zeolite growth process. There was significant improvement in the transport properties, with half of the membranes exhibiting CO2/N2 selectivity greater than 20. With the third group of membranes also grown in the flat geometry, care was taken to keep them flat through all the subsequent steps including washing, drying and putting on the PDMS layer. Transport properties improved further. The twelve membranes in this group exhibited CO2/N2 separation factor in the range of 16–110 with CO2 permeance in the range of 180–2000 GPU (1 GPU = 3.3 × 10−10 mol/m2·Pa).
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • Structural characterization of alkyl bonded MCM-41 silica materials
           prepared by supercritical fluid approach
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Tahira Yasmin , Klaus Müller
      A comprehensive study is conducted on alkyl bonded mesoporous MCM-41 silica materials prepared using supercritical carbon dioxide (sc-CO2) as a bonding medium. The higher surface coverages of resulting materials as compared with organic solvent produced bonded phases are attributed to greater accessibility of the silica silanols in sc-CO2. The variation in pore dimensions depends on the nature of bonded alkyl chains. The resulting materials are characterized before and after surface modification using various characterization techniques. The specific surface area is calculated using BET method while information about pore diameter is obtained by DFT calculations. The degree of organization is investigated by XRD and SEM analysis gives information about morphology of the material. The degree of bonding and cross-inking of the alkylsilanes is determined by 29Si NMR spectroscopy. 13C NMR and FTIR spectroscopies are employed to study the conformational behavior and mobility of the bonded alky chains.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • Simplified preparation of SnO2 inverse opal for Methanol gas sensing
           performance
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Jinquan Wang , Yanmei Xu , Weichao Xu , Ming Zhang , Xiaobing Chen
      As a novel structure, inverse opal, with three dimensional periodic macropore and mesopore, huge specific surface area, is promising in highly sensitive gas sensing. In this paper, SnO2 inverse opal was prepared with a simplified polystyrene (PS) opal template cooperating with sol–gel method. The simplified method could spare much work and avoid the operation of the SnO2 inverse opal scraped from microslide. The performance of the SnO2 inverse opal sensor to methanol gas was systemically investigated. The results indicate that the sensing performance of the SnO2 inverse opal sensor to methanol gas is highly improved than traditional sensors. The response of the SnO2 inverse opal sensor is as high as 95 for 500 ppm methanol gas detection. In the range from 1 to 1000 ppm, the SnO2 inverse opal sensor shows fine linear relationship with the growth of the methanol gas concentrations.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • Synthesis of mesoporous graphitic C3N4 using cross-linked bimodal
           mesoporous SBA-15 as a hard template
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Hui-Min Zhao , Chang-Miao Di , Lan Wang , Yuan Chun , Qin-Hua Xu
      Mesoporous graphitic C3N4 has been synthesized using a novel cross-linked bimodal mesoporous (CLBM) SBA-15 as a hard template. This cross-linked bimodal mesoporous SBA-15 template was prepared by adjusting the pH to alter the copolymer micelle size. The resulting mesoporous g-C3N4 replicates the morphology of the mesoporous silica template, and numerous pore openings are formed on the surfaces. The mesoporous g-C3N4 exhibits a high specific surface area and a large pore volume. The photocatalytic degradation activity of methyl orange on mesoporous g-C3N4 is nearly 15.3 times as high as that on bulk-g-C3N4 under visible light irradiation. The high photocatalytic performance of this sample is due to the high specific surface area and more readily accessible active sites.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • Molecular engineering of microporous crystals: (VIII) The
           solvent-dependence of the structure-directing effect of ethylenediamine in
           the synthesis of open-framework aluminophosphates
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Huiying Lu , Jun Xu , Pan Gao , Wenfu Yan , Feng Deng , Ruren Xu
      By heating two mixtures with the molar composition of Al2O3:3.0 P2O5:4.0 ethylenediamine (en):90 ethylene glycol (EG):7.9 H2O and Al2O3:3.0 P2O5:4.0 ethylenediamine (en):90H2O at 180 °C, one-dimensional (1D) chain-like aluminophosphate 1 ([AlP2O8H][N2C2H10]) and three-dimensional (3D) open-framework aluminophosphate AlPO4-12 ([Al3P3O13][N2C2H10]) were obtained, respectively. The crystallization processes were investigated using powder X-ray diffraction (XRD) and solid-state magic-angle spinning nuclear magnetic resonance (MAS NMR) techniques. The evolution of the coordination state of Al and P during the crystallization was monitored. A possible starting point (core unit) for the crystallization of both structures was suggested. The correlation between the core units and the long-range ordering of the planes first appeared in the early stage of both crystallization processes were investigated. The results show that the solvent can affect the structure-directing effect of ethylenediamine by altering the type and distribution of the fragments formed in the synthetic system and the starting point (core unit) of the crystallization, which will determine the structure of the resulting crystals. The long-range ordering along the direction that is represented by the diffraction peaks which appeared earlier than other diffraction peaks during the crystallization process might be formed from a core unit.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • Conjugated polymer and spirolactam rhodamine-B derivative
           co-functionalized mesoporous silica nanoparticles as the scaffold for the
           FRET-based ratiometric sensing of mercury (II) ions
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Lijuan Feng , Jie Sha , Yao He , Shaopeng Chen , Bingxin Liu , Haixia Zhang , Changli Lü
      A novel fluorescence resonance energy transfer (FRET)-based ratiometric nanosensor is reported for toxic Hg2+ ions detection. Poly(p-phenylenevinylene) (PPV) chain was encapsulated into the pores of mesoporous silica nanoparticles (MSNs) by ion-exchange and in situ polymerization, and used as the energy-transfer donor. A spirolactam rhodamine-B derivative (SRhB), as an ion recognition element and energy-transfer acceptor, was embedded in the pores of MSNs to form PPV@MSN@SRhB as the nanosensor. The presence of Hg2+ in the dispersion solution of nanoparticles can induce the ring-opening reaction of the SRhB moieties and lead to the occurrence of FRET process, affording the nanoparticle system a ratiometric sensor for Hg2+ ions. The nanoparticle sensor can selectively detect Hg2+ ions with a detection limit of 200 nM (ca. 40 ppb). It has been found that the fabricated FRET-based scaffold with the conjugated polymer as a donor exhibited high environmental stability and was more preferred for the accurate ratiometric sensing. Moreover, the FRET-based ratiometric nanosensor can be applicable in a relatively wide pH range (pH = 5–8) in solution.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • Mesoporous alumina infiltrated with a very thin and complete carbon layer
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Galina N. Ilinich , Ren I. Kvon , Artem B. Ayupov , Victor A. Chumachenko , Anatoly V. Romanenko
      The mesoporous composite material “carbon-infiltrated alumina” was synthesized via chemical vapor infiltration of pyrocarbon in a porous alumina (γ-Al2O3) matrix. The process was carried out under continuous flow conditions at 650–800 °C and 1 bar of the reaction gas mixture containing ethylene (5 or 15 vol. %) and Ar (balance). A number of the synthesis parameters were examined to determine the conditions that are necessary for the formation of a thin but complete carbon layer over the alumina surface. A special acquisition mode of X-ray photoelectron spectroscopy was suggested and validated for the fast and reliable testing of completeness and uniformity of the carbon deposits on the outer alumina surface. Low-temperature N2 adsorption and electron microscopy were used to study the porous structure of γ-Al2O3 after high-temperature pretreatments and the carbon-infiltrated materials as well as the same samples after treatment with an aqueous hydrochloric acid solution. As a result of these studies, the mesoporous carbon-infiltrated aluminas with an extremely thin (1–1.5 carbon layers) and complete carbon coating, high electrical conductivity and excellent endurance in acidic medium have been prepared.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • The effect of pore structure on the CO2 adsorption efficiency
           of polyamine impregnated porous carbons
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): J.A. Arran Gibson , Andrei V. Gromov , Stefano Brandani , Eleanor E.B. Campbell
      The effect of polyamine impregnation on the CO2 adsorption properties of two different porous carbons, one microporous and one mesoporous, was studied systematically. The pore filling during impregnation with polyamines was shown to result in a fraction of the unfilled micropore volume being blocked for gas adsorption. Thermal gravimetric analysis was used to compare the CO2 capacity at 0.1 bar with respect to the carbon support type, the amount of amine loading, and the type of amine. A 12 fold increase in the CO2 capacity was observed when the impregnated activated carbon was compared to the raw starting material. A heat of adsorption for amine impregnated support of ∼90 kJ mol−1 was found, clearly indicating a chemisorption mechanism. The mesoporous material provided a more efficient support for the amine to interact with the CO2. The interaction between low molecular weight amines and CO2 showed a more efficient utilization of the basic groups in comparison to high molecular weight species.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
 
 
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