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Journal of Polymer Science Part B: Polymer Physics     Hybrid Journal   (Followers: 22)
Journal of Porous Materials     Hybrid Journal   (Followers: 3)
Journal of Porphyrins and Phthalocyanines     Hybrid Journal   (Followers: 2)
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Journal of Synchrotron Radiation     Hybrid Journal   (Followers: 1)
Journal of Testing and Evaluation     Full-text available via subscription   (Followers: 11)
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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)
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Living Reviews in Relativity     Open Access  
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Macalester Journal of Physics and Astronomy     Open Access  
Machining Science and Technology: An International Journal     Hybrid Journal   (Followers: 2)
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Mass Spectrometry Reviews     Hybrid Journal   (Followers: 21)
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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)
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Nanotechnology Magazine, IEEE     Full-text available via subscription   (Followers: 18)
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Nature Communications     Open Access   (Followers: 48)
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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)

  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  [2586 journals]
  • Enhanced adsorption selectivity of dibenzothiophene on ordered mesoporous
           carbon-silica nanocomposites via copper modification
    • Abstract: Publication date: August 2015
      Source:Microporous and Mesoporous Materials, Volume 212
      Author(s): Jieling Cheng , Shuangling Jin , Rui Zhang , Xia Shao , Minglin Jin
      In this study, copper-modified ordered mesoporous carbon-silica nanocomposites (MCSs) were synthesized by incipient wetness impregnation of copper nitrate. The desulfurization performance of the as-prepared adsorbents was evaluated by the selective adsorption of dibenzothiophene (DBT) as model sulfur compound from model fuels at ambient conditions. For comparison, the adsorptive desulfurization capacity for copper species supported on pure silica SBA-15 and pure carbonaceous CMK-3 was also investigated, respectively. The results indicate that MCS with 10wt.% of copper performed highest selectivity for DBT in competition with benzene. The significantly enhanced desulfurization performance of MCS could be attributed to its hybrid mesoporous carbon-silica nature which is favorable for high dispersion extent of copper and synergistic effect between the carbon substrate and the supported copper species.
      Graphical abstract image

      PubDate: 2015-04-16T06:22:08Z
       
  • Divalent heavy metals adsorption onto different types of EDTA-modified
           mesoporous materials: Effectiveness and complexation rate
    • Abstract: Publication date: August 2015
      Source:Microporous and Mesoporous Materials, Volume 212
      Author(s): Zeinab Ezzeddine , Isabelle Batonneau-Gener , Yannick Pouilloux , Hussein Hamad , Zeinab Saad , Veronique Kazpard
      The removal of heavy metals from contaminated water was investigated using three types of ordered mesoporous silica (KIT-6, SBA-15 and SBA-16). The materials were functionalized with 3-aminopropyltrimethoxy-silane and ethylenediaminetetraacetic acid (EDTA) via two steps post grafting methods. Then the modified adsorbents were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen (N2) adsorption-desorption analysis, Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis. The ordering of the supports was not affected after modification. KIT-6 and SBA-15 were found to be more efficient than SBA-16 due to their structural characteristics. The adsorption experiments were then conducted under different experimental conditions, such as pH, contact time and initial metals concentrations. The kinetic adsorption data obtained for the divalent metals followed the pseudo-second-order model indicating chmisorption. The exchange velocity (k_w) of each metallic ion is the main factor controlling both the adsorption rate and the selectivity which were higher for Cu2+ and Pb2+ than for Ni2+ and Cd2+. The maximum adsorption capacities were calculated by Langmuir model and were highly dependent on the amount of immobilized EDTA.
      Graphical abstract image

      PubDate: 2015-04-16T06:22:08Z
       
  • Mesoporous titania with anatase framework synthesized using polyphenolic
           structure-directing agent: Synthesis domain and catalytic metal loading
    • Abstract: Publication date: August 2015
      Source:Microporous and Mesoporous Materials, Volume 212
      Author(s): Hye Sun Shin , Changbum Jo , Seung Hyeon Ko , Ryong Ryoo
      Crystalline anatase TiO2 with nanosponge-like mesoporous morphologies was solvothermally synthesized following the recently reported route using random copolymer (4-vinylphenol and methyl methacrylate) as structure-directing agent. In particular, the synthesis conditions were varied over a wide range of synthesis gel compositions. Crystallinity of the titania products was checked with X-ray powder diffraction. Mesopore diameters, pore volume and specific surface area were analyzed using nitrogen adsorption. The result provided proper synthesis domains for highly mesoporous titania materials. The mesoporous materials were evaluated as supports for catalytic Pt nanoparticles to apply for alcohol-to-aldehyde partial oxidation reactions.
      Graphical abstract image

      PubDate: 2015-04-16T06:22:08Z
       
  • Brønsted sites and structural stabilization effect of acidic
           low-silica zeolite A prepared by partial ammonium exchange
    • Abstract: Publication date: August 2015
      Source:Microporous and Mesoporous Materials, Volume 212
      Author(s): Michael Dyballa , Utz Obenaus , Swen Lang , Barbara Gehring , Yvonne Traa , Hubert Koller , Michael Hunger
      It is demonstrated for low-silica zeolite 25NH4,Na-A (n Si/n Al = 1.0) with an ammonium exchange degree of 25% that the formation of acidic bridging OH groups (Si(OH)Al) after thermal deammoniation is accompanied by a weak dealumination of the framework. As the extra-framework aluminum species mainly exist predominantly in the form of Al3+ cations, they partially neutralize negative framework charges. The remaining framework charges are compensated by Na+ cations and hydroxyl protons of Si(OH)Al groups. Therefore, a lower number of Si(OH)Al groups is formed than expected by the stoichiometry of the ammonium exchange. For zeolite 25NH4,Na-A, only 17% of the introduced ammonium ions form Si(OH)Al groups after thermal deammoniation. A benefit of the cationic extra-framework aluminum species (Al3+) is their stabilizing effect exerted on the remaining framework aluminum atoms and the whole structure of the obtained zeolite 25H,Na-A. 1H MAS NMR signals of acidic OH groups were observed at 3.6 and 4.8 ppm and assigned to Si(OH)Al groups in the α- and β-cages, respectively. A low-field signal at 13.3 ppm is probably due to Si(OH)Al groups, however, involved in H-bondings (Si(OH⋯O)Al) with hydroxyl protons directed to very near oxygen atoms, such as expected in double 4-rings of the LTA structure.
      Graphical abstract image

      PubDate: 2015-04-16T06:22:08Z
       
  • Hierarchically porous carbon–zirconium carbide spheres as
           potentially reusable transmutation targets
    • Abstract: Publication date: August 2015
      Source:Microporous and Mesoporous Materials, Volume 212
      Author(s): Nicholas Scales , Jun Chen , Tracey L. Hanley , Daniel P. Riley , Gregory R. Lumpkin , Vittorio Luca
      The preparation of hierarchically porous phase-pure carbon–zirconium carbide spheres with surface areas upwards of 70 m2/g and diameters in the 1–2 mm range has been achieved. The zirconium carbide beads were prepared through carbothermal reduction of polyacrylonitrile-zirconium composites prepared via three different routes including infiltration of a zirconium precursor into preformed polyacrylonitrile (PAN) beads and two one-pot co-precipitation methods. Depending on the route used to prepare the composites, relatively high surface area phase-pure zirconium carbides with the radial macroporous internal structure of the PAN template could be prepared. The adsorption of the elements U, Mo, Cs and Sr by the zirconium carbide beads was studied as a function of pH in the range 1–13 and target element concentrations of 0.025 mmol/L. The as-prepared hierarchical zirconium carbide beads demonstrated almost quantitative uptake of Mo below pH 4 with uptake decreasing to close to zero and above pH 10.5. On the other hand, U uptake was negligible below pH 4 and became quantitative in the range 4–12. Cesium was not extracted to any significant extent in the pH range studied and Sr only to a limited extent above pH 10. The engineered hierarchical porosities, neutron transparency, thermal stability and anticipated chemical stability of the present zirconium carbide spheres makes them promising candidates as reusable transmutation targets for Minor Actinide incineration.
      Graphical abstract image

      PubDate: 2015-04-16T06:22:08Z
       
  • A facile bio-replicated synthesis of SnO2 motifs with porous surface by
           using pollen grains of Peltophorum pterocarpum as a template
    • Abstract: Publication date: August 2015
      Source:Microporous and Mesoporous Materials, Volume 212
      Author(s): A. Ahamed Fazil , J. Udaya Bhanu , A. Amutha , S. Joicy , N. Ponpandian , S. Amirthapandian , B.K. Panigrahi , P. Thangadurai
      A bio-economical route for synthesizing highly crystalline SnO2 motifs with porous structures have been developed with the help of naturally obtained Peltophorum pterocarpum pollen grains. Fresh and dried pollen grains were directly used for the synthesis after rinsing with anhydrous ethanol. Stirring procedure with tin (IV) chloride pentahydrate solution followed by a suitable heat treatment provided a well-structured pollen morphology to the inorganic SnO2 motifs. The synthesized micro porous SnO2 motifs were characterized by DSC-TGA, XRD, UV–visible spectroscopy, SEM and TEM, BET and electron energy loss spectroscopy (EELS). The SnO2 motifs had a tetragonal rutile crystal structure and its maximum band gap was found to be 4.26 eV. The motifs were made up of SnO2 nanoparticles of size in the range from 16 to 25 nm as obtained from TEM analysis. The maximum BET surface area was found to be 82.72 m2g−1. The EELS analysis provided the elemental composition present in SnO2 motifs. A facile method for the production of micro porous SnO2 motifs along with their characteristics is elucidated in this report.
      Graphical abstract image

      PubDate: 2015-04-16T06:22:08Z
       
  • Editorial Board
    • Abstract: Publication date: 1 July 2015
      Source:Microporous and Mesoporous Materials, Volume 210




      PubDate: 2015-04-11T04:21:40Z
       
  • Effects of textural and surface characteristics of metal-organic
           frameworks on the methane adsorption for natural gas vehicular application
           
    • Abstract: Publication date: August 2015
      Source:Microporous and Mesoporous Materials, Volume 212
      Author(s): Jingmei Shen , Jacqueline Sulkowski , Matthew Beckner , Anne Dailly
      In this work, methane adsorption and textural and surface characteristics of selected 46 microporous metal-organic frameworks and 6 other adsorbents were measured experimentally. The objective of this work is to identify either the most relevant characteristics or a combination of multiple properties, which will qualify a given sample to be a good methane uptake material in a moderate pressure range (up to 70 bar) and at 298 K. It is found that there is an overall linear tendency between maximum excess methane adsorption and BET specific surface area. The micropore volume correlates to the maximum excess methane adsorption as well, irrespective of the chemistry and functionalities of materials. In addition, micropore size distribution has an impact on methane uptake. When considering the total methane uptake, special attention should be paid to the effect from packing density. The evaluation also focuses on the discussion of deliverable capacity and concludes that optimal adsorption enthalpy is desired to avoid large amount of methane retained at the minimum desorption pressure in practical vehicular applications.
      Graphical abstract image

      PubDate: 2015-04-11T04:21:40Z
       
  • Seed-directed synthesis of EMT-type zeolite from an organic-template-free
           system
    • Abstract: Publication date: August 2015
      Source:Microporous and Mesoporous Materials, Volume 212
      Author(s): Qin Mou , Niu Li , Shouhe Xiang
      EMT-type zeolite has been prepared by usage of seed directed method from an organic-template-free system (named as EMC-2-SOF). Powder X-ray diffraction (XRD) patterns verified that the diffraction patterns of EMC-2-SOF matched very well with EMC-2 synthesized using 18-crown-6 ether as template. EMT-type zeolite with complete diffraction patterns was prepared at high OH−/SiO2 ratio (more than 2.0) and low temperature (50 °C) for 3 days. It has been found that, without organic template, calcined EMC-2 (denoted as EMC-2-C) showed better directing effect than as-synthesized one for the synthesis of EMC-2-SOF. Besides, the variation of SiO2/Al2O3 molar ratio in original gel for synthesizing EMC-2-SOF was affected by OH−/SiO2 ratio. A best fit between the ratio of SiO2/Al2O3 and OH−/SiO2 has been achieved. At OH−/SiO2 = 2.0, the relative crystallinity of EMC-2-SOF first increased, then got to 100% at SiO2/Al2O3 = 50, and finally decreased with SiO2/Al2O3 ratio increasing. Meanwhile, by changing H2O/SiO2 ratio from 46.6 to 30, yield of EMC-2-SOF increased from 15.8 to 33.4 wt.%. A relationship of mutual compensation among three intensive parameters in preparing zeolites (alkaline, temperature and crystallization time) has been used to improve the crystallinity of EMC-2-SOF. When gels with SiO2/Al2O3 = 25, OH−/SiO2 = 2.0, H2O/SiO2 were crystallized at 55 °C for 12–20 h, all the samples had crystallinity above 100% with the yield over 25 wt.%.
      Graphical abstract image

      PubDate: 2015-04-11T04:21:40Z
       
  • Salt-assisted synthesis of mesostructured cellular foams consisting
           of small primary particles with enhanced hydrothermal stability
    • Abstract: Publication date: August 2015
      Source:Microporous and Mesoporous Materials, Volume 212
      Author(s): Youngjin Choi , Jinwoo Lee , Jaeyun Kim
      Mesoporous silica materials have attracted considerable attention as adsorbents, catalyst supports, and drug delivery carriers due to their large surface area, high pore volume, and controllable pore size. To increase the adsorption or mass transport properties, large pore sized mesoporous silica is highly desired. Here, we demonstrate a new green synthetic route for obtaining salt-assisted mesostructured cellular foams (S-MCFs) using a triblock copolymer as a single structure-directing agent by addition of inorganic salt without using a hydrophobic pore expander. The S-MCF was composed of ∼27 nm cellular pores and 10 nm windows and had distinct pore walls and a cellular structure. S-MCFs showed an enhanced hydrothermal stability compared to other mesocellular silica. In addition, the primary particle size of the S-MCF was 100–300 nm, which is much smaller than that of previously reported mesostructured cellular foams (MCFs) and mesocellular silica foam (MSU-F). The adsorption study using a model protein revealed that small primary particle size in S-MCF is beneficial for mass transfer in a short period of time. Therefore, S-MCF may serve as a potential platform for higher mass transport or adsorption of large molecules with good stability.
      Graphical abstract image

      PubDate: 2015-04-11T04:21:40Z
       
  • A biomimetic extracellular matrix composed of mesoporous bioactive glass
           as a bone graft material
    • Abstract: Publication date: August 2015
      Source:Microporous and Mesoporous Materials, Volume 212
      Author(s): Fu-Yin Hsu , Ru-Chun Weng , Hsiu-Mei Lin , Yi-Hsuan Lin , Meng-Ru Lu , Jing-Lun Yu , Hsien-Wen Hsu
      Mesoporous bioactive glass (MBG) has been demonstrated to play an important role in bone regeneration. In this study, the fabrication of a matrix composed of MBG nanofibers (MBGNFs) that mimics the three-dimensional structure of the natural extracellular matrix is reported. The fabrication process utilized a sol–gel/electrospinning technique. The morphology, composition, and structure of the MBGNF matrices were characterized. The MBGNF matrices were typically characterized by highly ordered, one-dimensional channels in a hexagonally packed mesostructure. The drug loading and release profiles of the MBGNF matrices were also investigated. MBGNF matrices had better drug-loading efficiency and could reduce the burst release of gentamicin sulfate and prolong its release over 10 days. Hence, MBGNF matrices are suitable as a drug carrier. Additionally, immersing an MBGNF matrix in a simulated body fluid resulted in the formation of a layer of bone-like apatite minerals on the surface of the MBGNFs. This finding demonstrated the excellent in vitro bioactivity of the MBGNF matrix. Based on a cellular adhesion assay and an analysis of cytoskeletal organization, we determined that MBGNF matrices provided an appropriate environment for cellular adhesion. The observed cellular proliferation; alkaline phosphatase activity; and protein expression levels of osteopontin, osteocalcin and bone sialoprotein demonstrated that MBGNF matrices promoted the proliferation, differentiation and mineralization of MG63 osteoblast-like cells. Finally, the bone regeneration ability of the MBGNF matrix was evaluated using a rat calvarial defect model. The results revealed that MBGNF matrices were biodegradable and enhanced bone regeneration. Therefore, given the above results, the MBGNF matrix has the potential to become a new bone graft material for bone tissue engineering applications.
      Graphical abstract image

      PubDate: 2015-04-11T04:21:40Z
       
  • Synthesis and comparative study of the photocatalytic performance of
           hierarchically porous polymeric carbon nitrides
    • Abstract: Publication date: 15 July 2015
      Source:Microporous and Mesoporous Materials, Volume 211
      Author(s): Yingyong Wang , Muhammad Farooq Ibad , Hendrik Kosslick , Jörg Harloff , Torsten Beweries , Jörg Radnik , Axel Schulz , Stefanie Tschierlei , Stefan Lochbrunner , Xiangyun Guo
      Graphitic carbon nitride materials with tri-s-triazine and s-triazine based structures were prepared by thermal condensation of melamine (CNT) and by solution reaction of cyanuric chloride with lithium nitride (CNS), respectively. An amphiphilic block copolymer-F68 was used as a soft template for the synthesis of mesoporous carbon nitride. The structural and photophysical properties of the as-prepared catalysts were characterized by X-ray powder diffraction, elemental analysis, N2-adsorption measurement, transmission electron microscopy, X-ray photoelectron spectroscopy, differential scanning calorimeter and UV–Vis absorption as well as time-resolved picosecond emission spectroscopy. The photocatalytic activity of the samples was evaluated by H2 evolution from water under visible light irradiation and the degradation of rose bengal (RB). The mesoporous CNT materials prepared with Pluronic F68 as template showed markedly higher activity compared to bulk carbon nitride, which can be attributed to its crystallinity, hierarchical porous structure and the enlarged surface area. The catalyst was relatively stable as proven by recycling experiments. Besides, the addition of H2O2 promoted the formation of active ·OH radicals and increased the activity of carbon nitride for photodegradation of rose bengal. The carbon nitrides prepared by solution reactions were of very poor activity both in photocatalytic water splitting and rose bengal degradation.
      Graphical abstract image

      PubDate: 2015-04-07T04:17:50Z
       
  • Effect of treatment with different bases on the catalytic properties
           of TS-1/SiO2 extrudates in propylene epoxidation
    • Abstract: Publication date: August 2015
      Source:Microporous and Mesoporous Materials, Volume 212
      Author(s): Wancang Song , Guang Xiong , Huayun Long , Fengying Jin , Liping Liu , Xiangsheng Wang
      The effect of treatment with organic bases (ethylamine (EA), tetramethylammonium hydroxide (TMAOH), tetraethylammonium hydroxide (TEAOH) and tetrapropylammonium hydroxide (TPAOH)) on the catalytic properties of TS-1/SiO2 extrudates was investigated in the epoxidation of propylene. The morphology and MFI structure of the TS-1 were destroyed and the amount of non-framework Ti species in the catalysts increased when the TS-1/SiO2 extrudates were treated with EA and TMAOH, due to desilication. These changes are opposite to the improvement of the catalytic properties. On the contrary, treatment with TEAOH and TPAOH made the crystalline structure of the catalysts more homogeneous and adjusted the distribution of Ti and Si in the catalysts. In addition, the acidity of the samples increased appreciably, the pore openings at the surface of the catalysts were expanded as revealed by a series of characterizations. Thus, the catalytic activity and stability of the two catalysts were substantially enhanced.
      Graphical abstract image

      PubDate: 2015-04-07T04:17:50Z
       
  • Synthesis of zeolites at low temperatures in fly ash-kaolinite mixtures
    • Abstract: Publication date: August 2015
      Source:Microporous and Mesoporous Materials, Volume 212
      Author(s): Claudia Belviso , Lorena C. Giannossa , F. Javier Huertas , Antonio Lettino , Annarosa Mangone , Saverio Fiore
      Coal fly ash from an Italian coal-fired power plant, kaolinite from the Source Clay Repository of The Clay Minerals Society, and four derived mixtures were used to synthesize zeolite using hydrothermal treatment at 45 °C in distilled water after alkaline fusion. The results documented that geopolymers, A-type and X-type zeolites were formed in different quantities, depending on the starting material and the duration of the experiment. Zeolite-X was the prevailing phase synthesized using pure fly ash, zeolite-A formed in higher amounts from kaolinite, and comparable amounts of A- and X-type zeolites crystallized, thereby adding 20 and 40% kaolinite to the fly ash, respectively. Zeolite-A as main phase was synthesized already adding 60% or even up to 80% kaolinite to the fly ash. Sodalite occasionally formed from the source materials, whereas zeolite ZK-5 was synthesized from only fused fly ash (100FA). The data indicated that, in addition to the Si/Al ratio of solid source materials, zeolite formation was controlled by the time and chemistry of the solution. The polymerization of alumina-silicate gels changed during the experiments, likely due to the amorphization of metastable zeolites.
      Graphical abstract image

      PubDate: 2015-04-07T04:17:50Z
       
  • Titanium impregnated borosilicate zeolites for epoxidation catalysis
    • Abstract: Publication date: August 2015
      Source:Microporous and Mesoporous Materials, Volume 212
      Author(s): Jan Přech , Dana Vitvarová , Lenka Lupínková , Martin Kubů , Jiří Čejka
      Titanium containing molecular sieves, known as effective epoxidation catalysts, can be prepared either by direct synthesis or by post-synthesis impregnation. Controlled incorporation of titanium during the post-synthesis modification can be achieved when titanium atoms are inserted into the framework positions previously occupied by heteroatoms such as boron. In this contribution, we report the post-synthesis incorporation of titanium into borosilicates SSZ-24, SSZ-33, SSZ-42 and CIT-5. Parent borosilicates were deboronated using an HCl solution and subsequently impregnated with titanium (IV) butoxide or titanium (IV) chloride. The character of the titanium active sites was investigated using DR-UV/Vis spectroscopy showing that the titanium was incorporated into the framework positions with tetrahedral coordination. In some samples, other titanium species were present as well. The prepared Ti-SSZ-33 provides high yield of cyclooctene oxide 28.3% (after 240 min at 60 °C in acetonitrile, substrate/catalyst ratio = 10, H2O2 used as oxidant) in comparison with commonly used TS-1 (2.9%). On the other hand, impregnated zeolites SSZ-24, SSZ-42 and CIT-5 provided lower yields of cyclooctene oxide then the TS-1. The materials were found to catalyse the epoxidation of norbornene and linalool as well. The order of catalysts performance was similar for both substrates: Ti-SSZ-33 (norbornene oxide yield 15.4% after 240 min) > Ti-CIT-5 (yield 3.3%) > TS-1(yield 1.8%) > Ti-SSZ-42 (yield 0.8%); Ti-SSZ-33 (linalool oxide yield 13.3% after 320 min) > Ti-CIT-5 (yield 3.6%) > TS-1(yield 3.5%) > Ti-SSZ-42 (yield 1.3%)>Ti-SSZ-24 (yield 0.5%).
      Graphical abstract image

      PubDate: 2015-04-07T04:17:50Z
       
  • Efficient oxidative coupling of thiols and oxidation of sulfides using UHP
           in the presence of Ni or Cd salen complexes immobilized on MCM-41
           mesoporous as novel and recoverable nanocatalysts
    • Abstract: Publication date: 15 July 2015
      Source:Microporous and Mesoporous Materials, Volume 211
      Author(s): Mohsen Nikoorazm , Arash Ghorbani-Choghamarani , Houri Mahdavi , Saied Mostaffa Esmaeili
      Oxidation of sulfides to sulfoxides and oxidative coupling of thiols into their corresponding disulfides were carried out using urea-hydrogen peroxide (UHP) as oxidizing agent and immobilized Ni or Cd complexes on MCM-41 as stable, heterogeneous, efficient and recoverable catalysts under mild reaction conditions. These supported complexes were characterized by FT-IR spectroscopy, thermogravimetric analysis (TGA), powder X-ray diffraction (XRD) and N2 adsorption–desorption isotherms. A variety of aromatic and aliphatic sulfides and thiols with different functional groups were successfully oxidized with short reaction times in good to excellent yields at room temperature. Catalysts were easily recovered and reused for several consecutive runs without significant loss of their catalytic activity and efficiency.
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      PubDate: 2015-04-01T10:40:28Z
       
  • Ordered mesoporous carbons as effective sorbents for removal of heavy
           metal ions
    • Abstract: Publication date: 15 July 2015
      Source:Microporous and Mesoporous Materials, Volume 211
      Author(s): Mariusz Barczak , Katarzyna Michalak-Zwierz , Karolina Gdula , Katarzyna Tyszczuk-Rotko , Ryszard Dobrowolski , Andrzej Dąbrowski
      Herein, we report the systematic study on adsorption of heavy metal ions by ordered mesoporous carbon CMK-3. This sorbent has been obtained by hard templating using SBA-15 and subsequently, oxidized (by treatment with (NH4)2S2O8/H2SO4) and amino-functionalized (by treatment with N-(3-trimethoxysilylpropyl)diethylenetriamine). Pristine, oxidized and amino-functionalized carbons have been characterized by nitrogen sorption, X-ray diffractometry, X-ray photoelectron spectroscopy, scanning and transmission electron microscopy and tested for their ability to adsorb heavy metal ions (Pb, Zn, Cu, Cd) from the aqueous solutions. The observed static sorption capacities are very high up to 0.8 mmol/g and were at least twice higher than the values corresponding to the commercial activated carbon Norit® SX2. Adsorption kinetics is also very fast – for majority of the systems ∼90–95% of the equilibrium amount is adsorbed after several minutes. Desorption efficiencies of the adsorbed heavy metals vary from 41% (for Zn) to 99% (for Pb).
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      PubDate: 2015-04-01T10:40:28Z
       
  • Sequestration of cerium(III) bromide into mesoporous silica
    • Abstract: Publication date: 15 July 2015
      Source:Microporous and Mesoporous Materials, Volume 211
      Author(s): William L. Boncher , Terri C. Lin , Nikolaus L. Cordes , Markus P. Hehlen
      A variety of surface-functionalized mesoporous silica monoliths were reacted with a cerium(III) bromide molecular complex and a successful scaffold for luminescent materials is demonstrated. The variation in structure of the materials is shown through infrared spectroscopy, and the luminescent properties illustrate the varying coordination environment of cerium(III) bromide.
      Graphical abstract image

      PubDate: 2015-04-01T10:40:28Z
       
  • Airflow-induced nanochannel orientation in mesoporous polymers and carbon
           films
    • Abstract: Publication date: 15 July 2015
      Source:Microporous and Mesoporous Materials, Volume 211
      Author(s): Yimeng Wu , Xuemin Lu , Qinghua Lu
      Ordered mesoporous polymers and carbon films with controllable orientation of two-dimensional (2D) cylinders exhibit interesting properties for many applications. However, the preparation of such films is challenging because of inefficient present methods, which are effective for the preparation of mesoporous metal films. Here, a simple and facile method was developed to control the orientation of nanochannels by the airflow method. The nanochannels in mesoporous polymers and carbon films were strictly arranged along the airflow direction as determined by cross-section transmission electron microscopy and grazing-incidence small-angle X-ray scattering results. The orientation degree of the nanochannels was affected by the airflow speed and precursor concentration. The universality of this method in controlling the nanochannel orientation in various mesostructured films was discussed based on the shearing force generated during the interaction between airflow and precursor solution and the rapid evaporation of the solvent.
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      PubDate: 2015-04-01T10:40:28Z
       
  • Space-confined preparation of high surface area tungsten oxide and
           tungsten nitride inside the pores of mesoporous silica SBA-15
    • Abstract: Publication date: 15 July 2015
      Source:Microporous and Mesoporous Materials, Volume 211
      Author(s): Simon Meyer , Hans Beyer , Klaus Köhler , Annemette Hindhede Jensen , Erik Christensen , Niels J. Bjerrum
      For the direct preparation of high surface area nitride materials, a lack of suitable precursors exists. Indirect preparation by gas phase nitridation (e.g. by ammonia) requires high temperatures and often results in sintering. The present work demonstrates that the space-confined preparation of W2N inside the pores of ordered mesoporous silica SBA-15 offers a possibility to reduce sintering phenomena and thus to obtain smaller particles, porous structures and a higher surface area material. The preparation was pursued in a two-step approach. First, WO3 was introduced into the channels of SBA-15 and second, ammonolysis was conducted for its conversion to W2N. When performed in the presence of the exotemplate, SBA-15 acts as a stabilizer and small W2N particles (6–7 nm) with a high specific surface area (40 m2 g−1) are obtained after template removal. When the template is, however, removed before nitridation, it cannot stabilize the W2N particles and enhanced sintering occurs.
      Graphical abstract image

      PubDate: 2015-04-01T10:40:28Z
       
  • Novel carbon nanofibers build boron carbonitride porous architectures with
           microwave absorption properties
    • Abstract: Publication date: 15 July 2015
      Source:Microporous and Mesoporous Materials, Volume 211
      Author(s): Tao Zhang , Sifan Zeng , Guangwu Wen , Jiaqi Yang
      Boron Carbonitride (BCN) porous architectures build by carbon nanofibers and BCN precursor were successfully synthesized via a simple precursor pyrolysis method. Scanning electron microscope (SEM) and BET results showed the BCN porous architectures having the pore size distribution ringing from 50 nm to 24 microns in diameter. Fourier transform infrared (FT-IR) and X-ray diffractometer (XRD) results indicate that the products have the chemical composition of h-BCN and graphite. The minimum reflection loss and the frequency bandwidth below −20 dB for BCN are −56.2 dB and 7.7 GHz respectively, indicating better microwave absorption properties.
      Graphical abstract image

      PubDate: 2015-04-01T10:40:28Z
       
  • Adsorptive desulfurization and denitrogenation of model fuel using HPW and
           NiO-HPW modified aluminosilicate mesostructures
    • Abstract: Publication date: 15 July 2015
      Source:Microporous and Mesoporous Materials, Volume 211
      Author(s): Sina Rashidi , Mohammad Reza Khosravi Nikou , Bagher Anvaripour
      The performance of the aluminosilicate mesostructure (MSU-S) and its modified forms with phosphotungstic acid (HPW) and nickel oxide-HPW (NiO-HPW) for desulfurization and denitrogenation of model diesel fuels were studied. According to the results of characteristic tests (N2 adsorption-desorption, XRD, SEM, and NH3-TPD), HPW incorporation causes higher acidity along with a negligible loss in structural aspects, while NiO-HPW impregnation leaves a negative effect on mesoporous structure, crystalline phase, and particle shape along with a high positive impact on surface acidity. With NiO-HPW modification, the maximum increase of 33.18% and 6.88% is occurred for the adsorption loading of total sulfur and total nitrogen, respectively. Both modified adsorbents perform selective towards nitrogen removal over sulfur compounds. The pseudo-second order model can best fit the kinetics data and Freundlich model can best describe the equilibrium isotherm for all species over NiO/HPW-MSU-S.
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      PubDate: 2015-04-01T10:40:28Z
       
  • Learning from ancient Maya: Preparation of stable palygorskite/methylene
           blue@SiO2 Maya Blue-like pigment
    • Abstract: Publication date: 15 July 2015
      Source:Microporous and Mesoporous Materials, Volume 211
      Author(s): Yujie Zhang , Ling Fan , Hao Chen , Junping Zhang , Yuan Zhang , Aiqin Wang
      A facile method for the preparation of stable palygorskite/methylene blue@SiO2 (PAL/MB@SiO2) Maya Blue-like pigment was reported. The PAL/MB pigment was prepared via adsorption of MB by PAL, which was further coated with a layer of SiO2 by polycondensation of tetraethoxysilane (TEOS) with acetic acid (HAc) as the catalyst to form the PAL/MB@SiO2 pigment. The weight ratio of MB to PAL, ball milling time and heating temperature play important roles in affecting stability of the PAL/MB pigment. The MB content in the PAL/MB pigment is up to 12%, which is higher than all the state-of-the-art Maya Blue-like pigments. The MB molecules can only be adsorbed onto the external surface, the grooves and the openings of the channels of PAL, but cannot enter the channels according to the BET, zeta potential, FTIR and XRD analyses. Owing to the fact that the stability of the PAL/MB pigment is not very high, a layer of SiO2 is introduced to shield the MB molecules and further improve the stability. The PAL/MB@SiO2 pigment shows excellent stability against elution, thermal aging and intensive UV irradiation. A TEOS/HAc/H2O molar ratio of 1/2/140 in forming the SiO2 layer is greatly helpful to improve the stability.
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      PubDate: 2015-04-01T10:40:28Z
       
  • A hygrothermal modelling approach to water vapour sorption isotherm design
           for mesoporous humidity buffers
    • Abstract: Publication date: 15 July 2015
      Source:Microporous and Mesoporous Materials, Volume 211
      Author(s): Fernando Sarce Thomann , Matthew R. Hall , Wantana Sangchoom , Robert Mokaya
      This paper describes the development of a design technique using hygrothermal numerical modelling for top-down predictive design and optimisation of water vapour sorption isotherms to match any humidity buffering application. This was used to inform the design and synthesis of two new mesoporous silica (MS) materials suitable for specific applications. To validate the technique, the new materials were experimentally assessed using gravimetric dynamic vapour sorption (DVS). The experimental isotherms closely matched the optimised isotherm predictions from the design stage, and a positive correlation was observed between the rate of change in adsorbed water content, Δw and the time taken to exceed the permissible upper limit of humidity, φ i,U in a closed environment. A positive non-linear correlation was determined between the interior volumetric moisture load, ω ml and the mass of adsorbent required to fully achieve humidity buffering between specified lower/upper limits (φ i,L and φ i,U ). The kinetics of water vapour sorption/desorption were found to have general agreement when using the current hygrothermal numerical model. Current hygrothermal models appear to significantly underestimate the rate of adsorption/desorption in rapid-response mesoporous silica type materials. This is perhaps largely due to the current lack of consideration for scanning curve prediction within hysteresis loops and so is a priority for future research.
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      PubDate: 2015-04-01T10:40:28Z
       
  • Facile preparation of SBA-15-supported carbon nitride materials for
           high-performance base catalysis
    • Abstract: Publication date: 15 July 2015
      Source:Microporous and Mesoporous Materials, Volume 211
      Author(s): Jie Xu , Ting Chen , Jie-Kun Shang , Kai-Zhou Long , Yong-Xin Li
      SBA-15-supported carbon nitride materials were prepared using dicyandiamide as a precursor through a facile impregnation method. The synthesized CND/SBA-15 materials were characterized by various techniques, including N2 adsorption–desorption, small angle X-ray scattering, transmission electron microscopy, Fourier transform infrared (FT-IR), CO2 temperature-programmed desorption, etc. The results indicated that CND/SBA-15 retained the well-ordered mesoporous structure of SBA-15. The introduction of CN materials enhanced the overall basic quantity of SBA-15 and the basic sites were owing to the nitrogen-containing sites of CN materials, as revealed by FT-IR results. As solid base catalysts, CND/SBA-15 materials featuring easy preparation as well as high catalytic performances demonstrated their potential application in both Knoevenagel condensation and transesterification reactions.
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      PubDate: 2015-04-01T10:40:28Z
       
  • Mesoporous Fe/C and Core–Shell Fe–Fe3C@C composites as
           efficient microwave absorbents
    • Abstract: Publication date: 15 July 2015
      Source:Microporous and Mesoporous Materials, Volume 211
      Author(s): Guomin Li , Liancheng Wang , Wanxi Li , Yao Xu
      Mesoporous Fe/C and core–shell Fe–Fe3C@C composites were successfully prepared through the in-situ polymerization of Fe3+/phenolic resin coupled with F127 and the subsequent high-temperature carbonization. The experiments involved the preparation of an iron-containing carbon precursor and the heat-treatment process. Two composites with different morphology and structure could be obtained by changing the content of Fe(NO3)3·9H2O in the precursor. The crystalline phase, structure and microwave absorption of the two composites were investigated. Fe particles were uniformly embedded into the mesoporous networks to form mesoporous Fe/C composite with high surface area of 467.3 m2/g and low density of 1.92 g/cm3. The Fe–Fe3C particles encapsulated by graphitized carbon layers formed the core–shell structure with surface area and density of 259.5 m2/g and 2.67 g/cm3. Fe/C and Fe–Fe3C@C composites exhibited excellent electromagnetic absorbing ability, the effective absorption bandwidth reached 3.36 and 5.04 GHz with the matching thicknesses of 2 and 1.5 mm correspondingly. This originated mainly from the effective impedance match and multiple interfacial polarizations. Furthermore, the increase of Fe3+ not only promoted the graphitization degree of carbon shell, but also increased the complex permittivity and permeability of core–shell structure, thus improved the impedance matching. Owing to high surface area, low density and excellent microwave absorbability, the mesoporous Fe/C and core–shell Fe–Fe3C@C composites are promising candidates as lightweight and high-efficiency microwave absorbents.
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      PubDate: 2015-04-01T10:40:28Z
       
  • Complexes of N,N-bis (salicylidene)4,5-dimethyl-1,2-phenylenediamine
           immobilized on porous nanomaterials: Synthesis, characterization and study
           of their antimicrobial activity
    • Abstract: Publication date: August 2015
      Source:Microporous and Mesoporous Materials, Volume 212
      Author(s): F. Zamani , M. Zendehdel , A. Mobinikhaledi , M. Azarkish
      A new hybrid antibacterial material was developed by post synthesis grafting method. 3-aminopropyl triethoxysilane (3-APTES) was first anchored over MCM-41 and NaY Zeolite upon reaction with transition metal (M = Mn(II), Co(II) and Cu(II)) complexes of tetradentate Schiff base ligand L: (C22H20N2O2). The prepared materials were characterized by several techniques: chemical analysis, diffuse reflectance spectroscopy (DRS), Fourier transfer infrared (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Burner–Emmet–Taller(BET). The in vitro antibacterial activity of these compounds was evaluated against Staphylococcus aureus (S. aureus) and Bacillus subtilis (B. subtilis), as Gram-positive bacteria, and further against Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa), as Gram-negative bacteria. Then, the results were compared with standard drugs. The analysis revealed that hybrid materials that prepared by immobilization Schiff base in porous materials show fine inhibition on bacterial growth till 24 h.
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      PubDate: 2015-04-01T10:40:28Z
       
  • Long and local range structural changes in M[(bdc)(ted)0.5]
           (M = Zn, Ni or Cu) metal organic frameworks upon spontaneous
           thermal dispersion of LiCl and adsorption of carbon dioxide
    • Abstract: Publication date: August 2015
      Source:Microporous and Mesoporous Materials, Volume 212
      Author(s): Jennifer Guerrero-Medina , Génesis Mass-González , Leonardo Pacheco-Londoño , Samuel P. Hernández-Rivera , Riqiang Fu , Arturo J. Hernández-Maldonado
      Impregnation and thermal dispersion of LiCl were performed onto M(bdc)(ted)0.5 (M = Zn, Ni or Cu) metal-organic frameworks (MOFs). X-ray diffraction (XRD) indicated that LiCl was homogeneously dispersed into the pore channels of the Zn and Ni variants. A displacement of the peaks related to the diffraction planes (110), (002), (200) and (220) suggests that the structures suffer an expansion/contraction process. However, for Cu(bdc)(ted)0.5 the data revealed a remarkable loss in crystallinity. 13C cross-polarization magic angle spinning nuclear magnetic resonance (13C CPMAS NMR) and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy suggests a LiCl location near the secondary building unit of the Zn based MOF while Raman spectroscopy shows what appears to be a band corresponding to the formation of a Zn–Cl bond. X-ray photoelectron spectroscopy (XPS) data gathered for the Cu variant exhibited a shift in binding energy in the 2p3 line probably related to a change in the metal node valence from cupric to cuprous. When combined with the 13C CPMAS NMR, DRIFT and Raman data, this observation suggests destruction of the Cu(bdc)(ted)0.5 framework plausibly due to the formation of a CuCN·LiCl complex. Adsorption–desorption of CO2 onto the LiCl and apohost M(bdc)(ted)0.5 (M = Zn or Ni) also resulted in structural changes. A significant hysteresis was observed in the case of (LiCl)[Zn(bdc)(ted)0.5]. In addition, different equilibration time intervals revealed what appears to be a multi-domain or pseudo equilibrium process, involving structural changes characterized by time-scales larger in comparison to those required for adsorption–desorption equilibrium.
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      PubDate: 2015-04-01T10:40:28Z
       
  • Development of hierarchical MCM-49 zeolite with intracrystalline mesopores
           and improved catalytic performance in liquid alkylation of benzene with
           ethylene
    • Abstract: Publication date: August 2015
      Source:Microporous and Mesoporous Materials, Volume 212
      Author(s): Ningning Gao , Sujuan Xie , Shenglin Liu , Wenjie Xin , Yang Gao , Xiujie Li , Huijuan Wei , Hui Liu , Longya Xu
      Hierarchical MCM-49 zeolite with intracrystalline mesopores was prepared through post-treating the conventional MCM-49 zeolite in hexadecyltrimethylammonium bromide (CTAB) and NaOH mixed solution. N2 adsorption and desorption, XRD, TEM, XRF, ICP and Py-IR techniques were applied to characterize the obtained samples. It was found that uniform intracrystalline mesopores were distributed in the MCM-49 crystals, and the intracrystalline meso-porosity could be modified by changing the post-treatment conditions such as CTAB concentration, NaOH concentration, temperature and time. Based on the characterization results upon the hierarchical MCM-49 zeolite samples obtained by post-treating different time, the formation of intracrystalline mesopores in MCM-49 zeolite was proposed, which followed a CTAB micelle directed desilication mechanism. By virtue of the intracrystalline mesopores, the hierarchical MCM-49 zeolite prepared under proper post-treatment condition exhibited superior stability than the conventional MCM-49 zeolite in liquid alkylation of benzene with ethylene.
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      PubDate: 2015-04-01T10:40:28Z
       
  • 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.
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      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.
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      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.
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      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.
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      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.
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      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.
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      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.
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      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.
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      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
       
  • 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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      PubDate: 2015-03-05T22:07:14Z
       
  • 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.
      Graphical abstract image

      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.
      Graphical abstract image

      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
       
 
 
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