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  Subjects -> PHYSICS (Total: 744 journals)
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PHYSICS (544 journals)            First | 1 2 3 4 5 6 | Last

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  
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     Full-text available via subscription  
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: 9)
Journal of the American Society for Mass Spectrometry     Hybrid Journal   (Followers: 15)
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: 3)
Journal of Vibration and Control     Hybrid Journal   (Followers: 10)
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: 10)
Lasers in Surgery and Medicine     Hybrid Journal  
Latvian Journal of Physics and Technical Sciences     Open Access  
Learning Technologies, IEEE Transactions on     Hybrid Journal   (Followers: 9)
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: 3)
Magnetic Resonance Materials in Physics, Biology and Medicine     Hybrid Journal   (Followers: 1)
Magnetics Letters, IEEE     Hybrid Journal   (Followers: 1)
MAPAN     Hybrid Journal  
Mass Spectrometry Reviews     Hybrid Journal   (Followers: 16)
Matéria (Rio de Janeiro)     Open Access   (Followers: 1)
Materials & Design     Hybrid Journal   (Followers: 21)
Materials at High Temperatures     Full-text available via subscription   (Followers: 4)
Materials Chemistry and Physics     Full-text available via subscription   (Followers: 11)
Materials Research     Open Access   (Followers: 7)
Materials Research Bulletin     Hybrid Journal   (Followers: 15)
Materials Research Innovations     Hybrid Journal   (Followers: 2)
Materials Science     Hybrid Journal   (Followers: 7)
Materials Science and Engineering: A     Hybrid Journal   (Followers: 30)
Materials Science and Engineering: B     Hybrid Journal   (Followers: 15)
Materials Science and Engineering: C     Hybrid Journal   (Followers: 14)
Materials Science and Engineering: R: Reports     Hybrid Journal   (Followers: 10)
Materials Science and Technology     Hybrid Journal   (Followers: 15)
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: 1)
Microfluidics and Nanofluidics     Hybrid Journal   (Followers: 9)
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  
NANO     Hybrid Journal   (Followers: 6)
Nano Letters     Full-text available via subscription   (Followers: 40)
Nano Reviews     Open Access   (Followers: 15)
Nanoscale and Microscale Thermophysical Engineering     Hybrid Journal   (Followers: 3)
Nanoscale Research Letters     Open Access   (Followers: 4)
Nanotechnology Magazine, IEEE     Full-text available via subscription   (Followers: 12)
Natural Science     Open Access   (Followers: 9)
Nature Communications     Hybrid Journal   (Followers: 40)
Nature Materials     Full-text available via subscription   (Followers: 38)
Nature Physics     Full-text available via subscription   (Followers: 23)
NDT & E International     Hybrid Journal   (Followers: 10)
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: 3)
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: 11)
Nuclear Medicine and Biology     Hybrid Journal   (Followers: 1)
Nuclear Receptor     Full-text available via subscription   (Followers: 1)
Open Journal of Biophysics     Open Access   (Followers: 1)
Open Journal of Fluid Dynamics     Open Access   (Followers: 3)
Open Journal of Microphysics     Open Access  
Optical Communications and Networking, IEEE/OSA Journal of     Hybrid Journal   (Followers: 3)
Organic Electronics     Hybrid Journal   (Followers: 3)
PAJ: A Journal of Performance and Art     Hybrid Journal   (Followers: 11)
Particle Physics Insights     Open Access   (Followers: 2)

  First | 1 2 3 4 5 6 | Last

Journal Cover Microporous and Mesoporous Materials
   [5 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 1387-1811
     Published by Elsevier Homepage  [2563 journals]   [SJR: 1.306]   [H-I: 93]
  • CO2 desorption via microwave heating for post-combustion carbon capture
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Theo Chronopoulos , Yolanda Fernandez-Diez , M. Mercedes Maroto-Valer , Raffaella Ocone , David A. Reay
      In this work, a comparison of CO2 desorption rates of microporous activated carbon (AC) using Microwave Swing Desorption (MSD) and Temperature Swing Desorption (TSD) is reported. For the purposes of this study, a modified microwave oven and a conventional oven were used, heating the AC packed bed to two different temperatures (70°C and 130°C). Results showed that microwaves are able to enhance the rate of CO2 desorption from the AC, contributing to a four times faster overall desorption process, compared to conventional heating desorption.
      Graphical abstract image Highlights

      PubDate: 2014-07-28T17:46:59Z
       
  • Sulfur removal from municipal gas using magnesium oxides and a magnesium
           oxide/silicon dioxide composite
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Yo-Han Kim , Vu Anh Tuan , Myung-Kyu Park , Chang-Ha Lee
      Magnesium oxides (MgOs) were synthesized by polyol-meditation thermolysis, hydrothermal, and aerogel methods and utilized to remove sulfur compounds from municipal gas. The capacity to remove methyl mercaptan (291μmol/mol) from methane was evaluated by using an adsorption breakthrough method at different temperatures. Then, to improve the sulfur removal capacity, a MgO–SiO2 composite was developed using the aerogel method and its breakthrough capacity was compared to those of the MgOs. The synthesized MgOs and MgO–SiO2 composite were characterized by XRD, BET, TGA, and HR-TEM. The MgO prepared by the aerogel method had the highest surface area and sorption capacity among the as-synthesized MgOs. Furthermore, the sulfur sorption capacity of the MgO–SiO2 composite prepared by the same aerogel method as MgO was three times higher than the aerogel MgO even though the sorption capacity of SiO2 was negligible.
      Graphical abstract image Highlights

      PubDate: 2014-07-28T17:46:59Z
       
  • Polyallylamine and NaOH as a novel binder to pelletize
           amine-functionalized mesoporous silicas for CO2 capture
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Worasaung Klinthong , Chih-Hung Huang , Chung-Sung Tan
      A binder solution containing polyallylamine (PAA) and NaOH is proposed to construct pellets from powdered amine-functionalized mesoporous silica, thereby providing active sites for CO2 capture. Various powdered amine-functionalized adsorbents were prepared and pelletized, including 3-aminopropyltriethoxysilane-functionalized MCM-41 obtained through post-modification and direct synthesis, and polyethylenimine-loaded MCM-41 obtained through impregnation. The effects of the concentrations of PAA and NaOH on the strength, durability, and CO2 adsorption capacity of the pellets were evaluated, as the anhydrous and humid CO2 adsorption behavior and cyclic thermal stability. The pellets prepared after mixing the powdered adsorbents with an aqueous solution of 3wt% PAA and 2wt% NaOH exhibited the CO2 adsorption capacity slightly lower than the powdered adsorbent, a recovery of greater than 90% of the powdered adsorbents was observed, while their mechanical strength was over 0.4MPa and the weight could be retained over 90% in durability tests. Moreover, the pelletized adsorbents possessed the high thermal stability in cyclic adsorption/desorption. As a result, the proposed binder formula can be used to provide pelletized amine-functionalized adsorbents for CO2 capture from power plants.
      Graphical abstract image

      PubDate: 2014-07-28T17:46:59Z
       
  • Influence of support morphology on the detemplation and permeation of
           ZSM-5 and SSZ-13 zeolite membranes
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Nikolay Kosinov , Clement Auffret , Venkata G.P. Sripathi , Canan Gücüyener , Jorge Gascon , Freek Kapteijn , Emiel J.M. Hensen
      In this work we prepared α-alumina hollow-fiber supported SSZ-13 and ZSM-5 membranes by hydrothermal secondary growth. The effects of support surface roughness and porosity, zeolite topology and zeolite film thickness on the thermal behavior of composite membranes during detemplation were investigated. The quality of prepared membranes was characterized by SEM, single and mixture gas permeation tests and adsorption-branch permporometry. The surface roughness of α-alumina hollow fiber supports is shown to strongly influence the thermal stability of zeolite films. SSZ-13 and ZSM-5 membranes prepared on supports with rough surface could be safely detemplated without formation of cracks by calcination (450–500°C), whereas membranes prepared on very smooth surface supports were cracked under similar conditions. In such case ozonication at lower temperature was found to be effective to detemplate the membranes without formation of cracks.
      Graphical abstract image Highlights

      PubDate: 2014-07-28T17:46:59Z
       
  • Thermo-elastic behavior and P/T phase stability of TlAlSiO4 (ABW)
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): G. Diego Gatta , Paolo Lotti , Marco Merlini , Domenico Caputo , Paolo Aprea , Andrea Lausi , Carmine Colella
      The P/T phase stability and the thermo-elastic behavior of synthetic TlAlSiO4 [ABW framework type, space group Pna21, a= 8.2719(2), b= 9.4373(2), c= 5.4180(1)Å] have been investigated up to 950°C (at room-P) and up to 8GPa (at room-T) by means of in situ synchrotron powder diffraction with a diamond anvil cell and with a high-temperature furnace. The Rietveld structure refinement of TlAlSiO4 at room P/T confirms the general structure model previously reported. Only one independent Tl site, with full site occupancy and close to channel wall, represents the extra-framework population. No phase transition has been observed within the temperature- and pressure-range investigated. P – V data were fitted to a second-order Birch–Murnaghan Equation of State (BM-EoS), giving: V 0 =420.76(5)Å3, K T0 =48.8(2)GPa. The evolution of the lattice parameters with pressure shows a significantly anisotropic compressional pattern. The elastic parameters calculated with a “linearized” second-order BM-EoS are: K T0(a)=21.96(7)GPa for the a-axis; K T0(b)=68(1)GPa for the b-axis, and K T0(c)=112(2)GPa for the c-axis. The volume thermal expansion with T was modeled by the polynomial function: V(T)/V 0 =1+ α 0·ΔT + α 1·ΔT 2 =1+4.44(3)·10−5·ΔT −2.3(3)·10−9·ΔT 2. The anisotropic thermal scheme is characterized by a negative thermal expansion along [010] (i.e. α 0(b)=−8.5(1)·10− 6 °C−1), almost no expansion along [001] (i.e. α 0(c)=0.9(1)·10− 6 °C−1) and a positive expansion along [100] (i.e. α 0(a)=52.4(1)·10− 6 °C−1). A comparative analysis of the thermo-elastic behavior of the isotypic TlAlSiO4 and CsAlSiO4 is carried out.
      Graphical abstract image

      PubDate: 2014-07-28T17:46:59Z
       
  • Nanosilica and H-Mordenite incorporated Poly(ether-block-amide)-1657
           membranes for gaseous separations
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): R. Surya Murali , K. Praveen Kumar , A.F. Ismail , S. Sridhar
      Two types of inorganic fillers – nanosilica and H-Mordenite were embodied into the Poly(ether-block-amide)-1657 polymer matrix to prepare mixed matrix membranes. Effect of filler loading and applied feed pressure on the performance of membranes was investigated. The distribution of fillers in the polymers, structural characteristics and interaction of fillers with polymer in membranes were scrutinized by SEM, FTIR and XRD. Single gas permeance of CO2, N2, H2 and O2 through the membranes was determined at ambient temperature (30°C). The embodiment of nanosilica into the polymer matrix enhanced the permeance of all gases and it was found that CO2 diffuses significantly through the nanosilica and polymer matrix when compared to other gases. For 0.3wt.% Si/Pebax membrane, with increasing pressure from 10 to 30kg/cm2, permeance enhanced from 8.9 to 36.1GPU for CO2, 1.1 to 3.5GPU for H2, 0.49 to 1.3GPU for O2 and 0.12 to 0.43GPU for N2. The effect of H-Mordenite loading had revised the permeance from 1.1 to 5.4GPU for CO2, 0.56 to 0.87GPU for H2, 0.09 to 0.39GPU for O2 and 0.03 to 0.205GPU for N2. With increasing pressure, a significant enhancement in selectivity of CO2/N2 was noticed for both Si/Pebax and H-Mordenite/Pebax membranes. Thus Pebax mixed matrix membranes provide a possible means for separation of CO2/N2 and enrichment of O2 and N2 from the air.
      Graphical abstract image

      PubDate: 2014-07-28T17:46:59Z
       
  • Influence of preparation method on the performance of Zn-containing HZSM-5
           catalysts in methanol-to-aromatics
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Xianjun Niu , Jie Gao , Qing Miao , Mei Dong , Guofu Wang , Weibin Fan , Zhangfeng Qin , Jianguo Wang
      Zn-containing HZSM-5 zeolites (Zn/ZSM-5) were prepared by four methods including impregnation (IM), ion exchange (IE), physical mixing with ZnO (PM), and direct synthesis (DS); the influence of preparation method on the catalytic performance of Zn/ZSM-5 in the process of methanol-to-aromatics (MTA) was investigated. The results indicated that Lewis acid sites of zinc species (ZnOH+) are formed by introducing zinc into HZSM-5, at the expense of the silanol hydroxyl and proton acid sites. The distribution of acid sites and the nature of zinc species as well as the subsequent catalytic performance of Zn/ZSM-5 in MTA are significantly influenced by the preparation method for introducing zinc. In Zn(PM)/ZSM-5, zinc is mainly present as macro ZnO particles and trace ZnOH+ is formed by solid state reaction; in Zn(IM)/ZSM-5, ZnOH+ is the main ingredient, together with nano ZnO particles dispersed in the zeolite channel; in Zn(IE)/ZSM-5 and Zn(DS)/ZSM-5, however, only ZnOH+ species are observed. There is a linear correlation between the amount of ZnOH+ species and the selectivity to aromatics for MTA over the Zn/ZSM-5 catalysts prepared by different methods; ZnOH+ species may promote the dehydrogenation of light hydrocarbons to aromatics and suppress the hydrogen transfer reaction and the formation of alkanes by depressing the Brønsted acidity. Zn(DS)/ZSM-5 with small particle size and high mesoporous volume exhibits the longest catalytic lifetime, whereas Zn(IE)/ZSM-5 with high fraction of surface ZnOH+ species gives the highest selectivity to aromatics in MTA.
      Graphical abstract image

      PubDate: 2014-07-28T17:46:59Z
       
  • Synthesis and characterization of CeO2-incorporated mesoporous
           calcium-silicate materials
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Jianhua Zhang , Yufang Zhu
      CeO2-incorporated mesoporous calcium-silicate (CeO2–MCS) materials have been successfully prepared using triblock copolymer (P123) as a structure-directing agent. The effect of CeO2 incorporation on mesoporous structure, in vitro bioactivity, osteoblast cells’ response and drug delivery property of MCS materials were investigated. The results showed that CeO2–MCS materials maintained mesoporous structure with the surface area of 100–200m2/g and pore size peaked at 4–5nm. Furthermore, CeO2–MCS materials had similar apatite-formation ability and sustained drug delivery behavior to MCS materials. Most important, the CeO2 incorporation in MCS materials stimulated the proliferation and alkaline phosphatase (ALP) activity of osteoblast MC3T3-E1 cells. Therefore, CeO2–MCS materials with local drug delivery would be promising for bone regeneration.
      Graphical abstract image

      PubDate: 2014-07-28T17:46:59Z
       
  • Ordered nitrogen doped mesoporous carbon assembled under aqueous acidic
           conditions and its electrochemical capacitive properties
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Mingjiang Xie , Yifen Xia , Jiyuan Liang , Lanhua Chen , Xuefeng Guo
      With urea as nitrogen source, soluble phenol–urea–formaldehyde (PUF) resin is synthesized under basic conditions, and then an N-containing mesophase is obtained by co-assembly of the obtained PUF resin and block copolymer of F127 in acidic aqueous solution. The pyrolysis of the resultant mesophase in inert atmosphere produces a nitrogen-doped mesoporous carbon, which possesses a well-defined ordered mesoporous structure, large surface area (up to 537m2/g), uniform pore size (∼3.6nm) and large pore volume (∼0.49cm3/g). Multi-techniques, such as elemental analysis, X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS) are performed to characterize the samples; these analytic results indicate that the doped nitrogen mainly exists as pyridinic and pyrrolic nitrogen is successfully and homogeneously introduced into the skeleton of the mesoporous carbon. And more, the nitrogen content in the final ordered mesoporous carbon can be easily adjusted up to 3.85 wt.% by increasing the original ratio of urea to phenol. Electrochemical measurements show the nitrogen doped mesoporous carbon presents a higher specific capacitance (up to 225F/g) than nitrogen-free ones (169F/g) and exhibits a good electrochemical stability even after 1000 cycles at current density of 5.0A/g.
      Graphical abstract image Highlights With urea as nitrogen source, soluble phenol–urea–formaldehyde (PUF) resin is synthesized under basic conditions and then to co-assemble with block copolymer of F127 in acidic aqueous solution to fabricate nitrogen doped mesoporous carbon. Heteroatom of nitrogen is successfully and homogeneously introduced into the skeleton of the mesoporous carbon and the final doped carbon presents a higher specific capacitance (up to 225F/g) than nitrogen-free one (169F/g).

      PubDate: 2014-07-28T17:46:59Z
       
  • Rapid synthesis of SAPO-34 nanocatalyst by dry gel conversion method
           templated with morphline: Investigating the effects of experimental
           parameters
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Sima Askari , Zahra Sedighi , Rouein Halladj
      SAPO-34 nanoparticles were successfully synthesized by a dry gel conversion method using morpholine as a structure-directing agent. In this study, the effects of synthesis parameters, such as crystallization time, gel drying temperature and water content added in the crystallization stage, on crystallinity, shape and particle size of SAPO-34 are investigated and the advantages of the dry-gel conversion (DGC) method are described for the synthesis of SAPO-34 molecular sieves. The products were characterized by XRD, SEM, TEM, EDX, BET and NH3-TPD. The results show that the favorable phase of crystallinity has been improved by increasing the crystallization time, gel drying temperature and water content. Most of the particles have particle sizes lower than 500nm and it is an excellence of employing the DGC method despite using morpholine as a structure-directing agent. The high nucleation density and slow crystal growth after nucleation for SAPO-34 crystals in the dry gel conversion method result in the formation of nanoparticles. Contrary to the hydrothermal method in which at least 24h of the synthesis time is required to obtain crystalline SAPO-34, dry-gel conversion synthesis of samples leads to formation of fully crystalline SAPO-34 crystals taking only 6h. This has been observed as an important influence of dry-gel conversion synthesis on the activity and selectivity of the samples in the MTO reaction.
      Graphical abstract image

      PubDate: 2014-07-28T17:46:59Z
       
  • The synthesis of core–shell Fe3O4@mesoporous carbon in acidic medium
           and its efficient removal of dye
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Lin Liang , Qiancheng Zhu , Tongbao Wang , Fangxiao Wang , Jun Ma , Liqiang Jing , Jianmin Sun
      Magnetic core–shell Fe3O4@nSiO2@mSiO2 nanoparticles were first synthesized with P123 as template in acid condition, which possess high BET surface area (839m2 g−1) and large pore volume (0.9cm3 g−1). Then Fe3O4@nSiO2@mSiO2 nanoparticles were used as hard templates to synthesize Fe3O4@mesoporous carbon (Fe3O4@mC) with large surface area (971m2 g−1) and pore volume (1.4cm3 g−1). The high surface area and mesoporous structure of Fe3O4@mC favor its efficient adsorption of Rhodamine B in aqueous solution, which exhibited higher adsorption capacity of 198.9mgg−1 within 30min than the previous reports on magnetic mesoporous graphitic carbon and magnetic mesoporous resin. The superparamagnetic property of Fe3O4@mC made it easily separated by an external magnetic field and reused after ethanol extraction. The rapid and efficient adsorption of dye together with their ease in separation and regeneration suggests that Fe3O4@mC composites have great potential applications in environmental abatements.
      Graphical abstract image Highlights

      PubDate: 2014-07-28T17:46:59Z
       
  • Zeolite micromembrane fabrication on magnetoelastic material using
           electron beam lithography
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Vassiliki Tsukala , Dimitris Kouzoudis
      In the present study, electron beam lithography (EBL) is employed in the manufacturing of patterns of continuous Linde Type A (LTA) zeolite membranes. The patterns are down to the micrometer scale and they are composed of LTA micromembranes having all three dimensions in the micrometer scale. The control of the size and location of zeolite films or membranes onto specific substrates, will lead to new aspects for their use in microsensing, microelectronics and microreactor applications. Our focus is on the microsensing field, where a magnetoelastic ribbon (Metglas) is used as the sensing platform, since the Metglas/zeolite film composite has been successfully used for the detection of gases and VOCs in the past. Here we report on the first LTA zeolite micromembrane attached onto a previously EBL patterned PMMA coated Metglas substrate. The sensing ability of such a sensor could be significantly improved by using lower amount of zeolite film since it could lead to shorter response and recovery times. The conditions for the manufacturing of the LTA micromembranes onto the Metglas substrate are investigated and discussed in terms of EBL, seeding and hydrothermal synthesis parameters.
      Graphical abstract image

      PubDate: 2014-07-28T17:46:59Z
       
  • Synthesis of homogeneous silicophosphate xerogels by non-hydrolytic
           condensation reactions
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Ales Styskalik , David Skoda , Zdenek Moravec , Joshua G. Abbott , Craig E. Barnes , Jiri Pinkas
      A novel non-hydrolytic synthesis of silicophosphate xerogels and optimization of reaction conditions to obtain products with a high degree of condensation and a large specific surface area are presented. Homogeneous products with a high content of Si–O–P bonds and SiO6 moieties were synthesized by an ester elimination route at low temperature from silicon acetate, Si(OAc)4, and tris(trimethylsilyl)phosphate, OP(OSiMe3)3 (TTP). Depending on the reaction conditions (temperature, solvent, time) it was possible to control the degree of condensation (up to 85.7%) and porosity of amorphous xerogels (apparent surface areas from 230 to 568m2 g−1). The composition and morphology of the xerogels, volatile reaction byproducts, thermal transformations and surface modification with methanol were followed by elemental analysis, IR spectroscopy, thermal analysis TG-DSC, nitrogen adsorption, 13C, 29Si, and 31P solid-state NMR spectroscopy, and powder XRD.
      Graphical abstract image Highlights

      PubDate: 2014-07-28T17:46:59Z
       
  • Molecular simulation and modelisation of methane/ethane mixtures
           adsorption onto a microporous molecular model of kerogen under typical
           reservoir conditions
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Julien Collell , Guillaume Galliero , François Gouth , François Montel , Magali Pujol , Philippe Ungerer , Marianna Yiannourakou
      The prediction of mixture adsorption is a challenging task in gas industry when dealing with shales for both resources prospect or production forecast. In this work, we used molecular simulation and models to study the adsorption of methane/ethane mixtures onto a mature kerogen model under typical reservoir conditions (338K, up to 20MPa). Using Molecular Dynamics, we first generated microporous structures of kerogen, representative of field samples. Monte Carlo simulations in the Grand Canonical ensemble were used to produce pure compound and mixture adsorption isotherms on these adsorbent structures. The ability to predict simulation results of the Ideal Adsorbed Solution model and a modified statistical mechanical derivation of the Extended Langmuir model have been studied at low pressures (up to 1MPa) where species are supposed ideal and at higher pressures (up to 20MPa) where species non-ideality is partially introduced in the models. At low pressures, the adsorption isotherms predicted by the two models are in good agreement with the results from molecular simulation, independently of the confinement. At higher pressures, this agreement is only valid for the less confined structures and worsened as the micropore size decreases.
      Graphical abstract image

      PubDate: 2014-07-28T17:46:59Z
       
  • Comparative study of MCM-22 and MCM-56 modified with molybdenum –
           Impact of the metal on acidic and oxidative properties of zeolites
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Anna Wojtaszek-Gurdak , Maciej Trejda , Dorota Kryszak , Maria Ziolek
      Hydrogen forms of layered MCM-22 and delaminated MCM-56 zeolites were modified with molybdenum species. The structure/texture and surface properties as well as catalytic activity in methanol transformation and dibutyl sulphide oxidation were compared for the two types of modified zeolites. The difference in the distribution of hydroxyls in HMCM-22 and HMCM-56 (more Brønsted acid sites (BAS) on HMCM-22, their high strength on HMCM-22, and domination of external silanols in HMCM-56) determines the location and properties of MoO3. Mo species interact with BAS on Mo/HMCM-22, which results in good dispersion of MoO3 and harder reducibility of molybdenum. Preferential interaction of Mo species with silanols on the external surface of HMCM-56 leads to larger crystallites of MoO3 which are easier to reduce. The strength of BAS is lower in HMCM-56 than in HMCM-22 and it is reduced in HMCM-22 after modification with Mo species. The lower strength of BAS in HMCM-56 results in a higher selectivity to 2-butene in the transformation of methanol, reaching 98.5% for Mo/HMCM-56. Mo species play a crucial role in the oxidation of sulphide to sulphoxide by H2O2. MoO3 is less stable in Mo/HMCM-56 because of the weaker interaction with the external zeolite surface. It is leached to the solution during oxidation of dibutyl sulphide. Therefore, Mo/HMCM-22, where Mo species are stronger bound to the surface, is more effective catalyst for this reaction.
      Graphical abstract image

      PubDate: 2014-07-28T17:46:59Z
       
  • Superficially mesoporous Fe3O4@SiO2 core shell microspheres: Controlled
           syntheses and attempts in protein separations
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Juan Hu , Shaojie Huang , Xiao Huang , Zhuang Kang , Ning Gan
      Superficially mesoporous Fe3O4@SiO2 core shell microspheres have been synthesized by complex multi-step reactions. The microspheres show three-layered structure: a magnetic core encapsulated by a layer of dense silica and another layer of mesoporous silica. These Fe3O4@SiO2@mesoporous SiO2 microspheres (FSMM) are around 50–100nm. The outer porous shell can provide much larger surface area than traditional nonporous Fe3O4@SiO2 core shell particles, which is beneficial for enrichment and purification applications. The presence of the superparamagnetic core allows the particles to be isolated and recycled easily by external magnetic field. The pore size of the mesoporous layer of FSMM is further enlarged (E-FSMM) by hydrothermal treatment. The surface of FSMM and E-FSMM are modified with protein G for enrichment and separation of Immunoglobulin G (IgG). FSMM particles exhibit IgG binding capacity of 41mg/g, while the binding capacity of E-FSMM is as high as 51mg/g due to the larger pore size facilitating protein binding.
      Graphical abstract image Highlights

      PubDate: 2014-07-28T17:46:59Z
       
  • Use of a sacrificial layer for an efficient EISA synthesis of mesoporous
           carbon
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Benjamin E. Wilson , Stephen G. Rudisill , Andreas Stein
      Evaporation-induced self-assembly (EISA) is widely used as a method to produce uniform, mesoporous structures. However, it is both time-consuming and produces relatively low yields due to the need for a large substrate area to obtain optimal results. Herein we report the use of sucrose or KCl as sacrificial layers in the synthesis of mesoporous carbon through EISA. Even though this procedure introduces an additional synthesis step, it increases the obtained yield of carbon up to twofold, eliminates the need for tedious mechanical removal of the film from the substrate, significantly cuts down on the active processing time, and makes it easier to obtain extended self-supporting films compared to conventional methods. The carbon products were studied using gas sorption, small-angle X-ray scattering, and transmission electron microscopy, and no significant differences were observed for products grown on either sacrificial layer compared to a product grown directly on glass substrates.
      Graphical abstract image

      PubDate: 2014-07-28T17:46:59Z
       
  • Highly dispersed iron xerogel catalysts for p-nitrophenol degradation by
           photo-Fenton effects
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Julien G. Mahy , Ludivine Tasseroul , Anthony Zubiaur , Jérémy Geens , Magali Brisbois , Marcus Herlitschke , Raphaël Hermann , Benoît Heinrichs , Stéphanie D. Lambert
      Several iron xerogel catalysts were synthesized by hydrolysis and condensation of tetraethoxysilane (TEOS) and 3-(2-aminoethylamino)propyltrimethoxysilane (EDAS) which is able to form a chelate with iron ions. The EDAS/TEOS ratio strongly influences the texture of xerogel catalysts. The specific surface area and the micro- and mesoporous volume increase with this ratio. It seems that EDAS plays a nucleating agent role for silica particles and allows to anchor Fe-based moieties inside the silica network. Iron oxide nanoparticles of diameter 1–1.5nm and Fe3+ ions result, encapsulated in silica particles with sizes of about 10–30nm in diameter. The iron species was determined by Mössbauer spectroscopy and magnetometry measurements and only Fe3+ species were observed in xerogel catalysts. The Fenton and photo-Fenton effect of these catalysts were evaluated on the degradation of p-nitrophenol in aqueous media under different conditions. Results show that in the presence of H2O2, iron xerogel catalysts present a photo-Fenton effect, reaching 99% of degradation after 24h.
      Graphical abstract image Highlights

      PubDate: 2014-07-28T17:46:59Z
       
  • Fluoride removal by ordered and disordered mesoporous aluminas
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Chao Yang , Lili Gao , Yanxin Wang , Xike Tian , Sridhar Komarneni
      Highly ordered and disordered (MA-n) mesoporous aluminas with excellent fluoride adsorption performance have been successfully developed. The physicochemical and adsorption properties were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption–desorption isotherms and fluoride removal experiments. Highly ordered mesoporous structure (OMA) was produced by using aluminum metal organic as precursor and wormlike disordered mesoporous structure (MA-n, MA-cl) was synthesized from inorganic aluminum salt precursors. The synthesized mesoporous alumina with a large pore size distribution of 7–14nm and large surface areas in the range of 163–338m2/g are beneficial for transport of solution in interconnected mesoporous channels and the fluoride ion was anchored on plenty of surface hydroxyl groups which provide high fluoride adsorption capacity and efficiency. Adsorption kinetics was described by pseudo-second-order, pseudo-first-order and intra-particle pore diffusion models, while, their adsorption equilibrium isotherms were described reasonably well by Langmuir model. Maximum fluoride adsorption capacities of OMA-400, OMA-850 and MA-n were 135, 91 and 95mg/g, respectively, which are higher than many reported alumina based adsorbents. Due to the ordered mesoporous structure which decreases the liquid transfer resistance, the OMA-400 showed extremely faster adsorption kinetics with a removal of 90% of F− within 20min at an optimal pH of 6. Presence of other anions like SO4 2−, NO3 −, Cl− and HCO3 − effect on fluoride removal efficiency and desorption study of OMA-400 and OMA-850 were also determined and compared.
      Graphical abstract image

      PubDate: 2014-07-28T17:46:59Z
       
  • In situ preparation of nitrogen-rich and functional ultramicroporous
           carbonaceous COFs by “segregated” microwave irradiation
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Chiyao Bai , Juan Li , Songbai Liu , Xiaoyu Yang , Xiaodan Yang , Yin Tian , Kecheng Cao , Ying Huang , Lijian Ma , Shoujian Li
      The present research developed a strategy for in situ synthesizing functionalized ultra-microporous carbons by “segregated” microwave irradiation using covalent organic frameworks as simultaneous C and N source. The products have high N-doping concentration (>30wt%), narrow pore size distribution, and the surface area of 507 and 243m2/g at the pore size of 0.4 and 0.6nm, which are much larger than the specific area (2 and 117m2/g) of samples prepared by conventional heating. They exhibit outstanding chemical, irradiation and thermal stabilities. Meanwhile, the carbonaceous COFs could retain the bulk morphology of the precursors and possess a unique functional group (cyano) which is helpful in material characters or in further modification. The findings support the potential use of “segregated” microwave irradiation in preparation of functional microporous carbons without any other additional process, and this method can also overcome the drawbacks of conventional heating and expand the range of microwave irradiation. The thus-prepared carbons were used as adsorbents for uranium recovery from a simulated nuclear effluent containing 12 co-existent cations with different pH value (4.5, 2.5 and 1.0). Results from batch experiments showed the amount of uranium adsorbed accounts for unreported 80% of the total adsorption amount at pH 1.0 with uranium sorption capacity of 50mg/g. In addition, the carbonaceous COFs could be applicable to various fields, such as heavy metal removal, gas storage, and could be beneficial for exploration of the behaviors of ions in sub-nanometer pore (<1nm) in the fields of carbon super-capacitors.
      Graphical abstract image Highlights

      PubDate: 2014-07-28T17:46:59Z
       
  • The iron(III)-modified natural zeolitic tuff as an adsorbent and carrier
           for selenium oxyanions
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Sanja Jevtić , Iztok Arčon , Aleksander Rečnik , Biljana Babić , Matjaž Mazaj , Jelena Pavlović , Danka Matijaševic , Miomir Nikšić , Nevenka Rajić
      Se(IV) and Se(VI) anions are the dominant species of Se existing in aqueous systems. In this study, the iron(III)-modified natural zeolitic tuff (Fe-CLI) from the Serbian deposit Zlatokop has been investigated as an adsorbent for the Se oxyanions. Fe-CLI shows adsorption activity for both Se(IV) and Se(VI) which decreases with increasing pH. The adsorption capacity of Fe-CLI is found to be higher for Se(IV) than for Se(VI). Kinetics data follow the pseudo-second-order model and the obtained parameters k indicate that the rates of adsorption and desorption are higher for Se(VI). Extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) analyses reveal that Se is bound at the zeolite surface forming not only the Se–O–Fe but also Se–O–Si bonds. The adsorption mechanism depends of the type of oxo ions. Samples of zeolitic tuff which contain Se were tested as soil supplements for the cultivation of Pleurotus ostreatus mushrooms. The fungus adsorbed the inorganic Se from zeolitic tuff transforming it to a more valuable organically bound form.
      Graphical abstract image Highlights Pleurotus ostreatus cultivated on: (a) SeIV-CLI enriched substrate (right) and control sample (left) and (b) SeVI-CLI enriched substrate (right) and control sample (left).

      PubDate: 2014-07-28T17:46:59Z
       
  • Pseudomorphical synthesis of glasses with hierarchical macro- and
           mesoporosity
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Marie Guillot , Sabah El Mourabit , Johann Ravaux , Alexei Tokarev , Frédéric Goettmann , Agnès Grandjean
      Herein a new synthetic approach, based on pseudomorphical transformation using sodium hydroxide to attack silica matrix during the dissolution/precipitation process, is proposed. Porous silica with the formation of a new mesoporosity inside of glass samples and with the possibility to close its porosity by a thermal treatment is then obtained. Indeed we report on the simple and successful conversion of a purely macroporous glass (obtained via a Vycor® type synthesis) into a macro- and mesoporous solid without modification of the macroscopic shape of the solid. The obtained multi-porous silica was functionalised and further tested as a support for catalysis or solid phase extraction.
      Graphical abstract image

      PubDate: 2014-07-28T17:46:59Z
       
  • Effect of silica sources on nanostructures of
           resorcinol–formaldehyde/silica and carbon/silicon carbide composite
           aerogels
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Yong Kong , Ya Zhong , Xiaodong Shen , Sheng Cui , Maohong Fan
      The subject of this paper is the investigation of the effect of silica sources on microstructure of resorcinol–formaldehyde/silica composite (RF/SiO2) and carbon/silicon carbide composite (C/SiC) aerogels. Hybrid silica sources (HSS) were composed of 3-(aminopropyl)triethoxysilane (APTES) and tetraethoxysilane (TEOS) with different molar ratio. RF/SiO2 aerogel was obtained by a single-step sol–gel process followed by supercritical fluid drying (SCFD). C/SiC aerogel was formed from RF/SiO2 aerogel after carbothermal reduction. Scanning electron microscopy (SEM) and N2 adsorption/desorption were used to investigate the evolution of morphology and pore structures of aerogels. X-ray diffraction (XRD) and transmission electron microscopy (TEM) demonstrated that the as-prepared C/SiC aerogel was composed of carbon nanoparticle and α-SiC nanocrystal. The microstructure was hugely affected by the component of HSS. When the molar fraction of APTES in HSS was 60%, RF/SiO2 and C/SiC aerogels possessed the highest surface area and pore volume and the lowest thermal conductivity.
      Graphical abstract image Highlights

      PubDate: 2014-07-28T17:46:59Z
       
  • Water-switching of spin crossover in a gold cluster supramolecular system:
           From metal–organic frameworks to catenane
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Haitao Xu , Zhen-liang Xu , Osamu Sato
      The electronic switching centers of metal–organic frameworks (MOFs) and the catenane [FeAu(CN)2(bpd) m ·xH2O]·yH2O are sensitive to the presence of small molecules, and reversibly uptake and release water. The switching centers arise from the presence of Iron(II) spin crossover (SCO) centers within the framework lattice, and the SCO behaviors emerge in dehydrated samples. The water-exchanging MOFs may realize previously undeveloped materials, which can aid the development of electronic devices such as molecular switches.
      Graphical abstract image Highlights

      PubDate: 2014-07-28T17:46:59Z
       
  • Mesopororous Sn0.9−xIn0.1Cux(I)O2−δ gas sensors with
           selectivity to H2S working under humid air conditions
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Simona Somacescu , Petre Osiceanu , Jose Maria Calderon-Moreno , André Sackmann , Cristian E. Simion , Adelina Stănoiu
      Sn0.9− x In0.1Cu x (I)O2− δ (x =0.02; 0.03 and 0.05mol%) mesoarchitectures have been synthesized using an ionic surfactant (CTAB) as template for sensing applications. The procedure implies a facile, hydrothermal synthesis route in order to obtain mesoarchitectures built from nanoparticles. The sensors were obtained by screen-printing deposition onto planar Al2O3 substrates provided with interdigitated Pt electrodes on one side and a Pt heater on the back side. The assessment of the well organized porous structure, for the sensitive materials, as specific surface area and uniform pore size distributions were revealed by N2 adsorption/desorption. The morphological and structural features of the resultant material were investigated by scanning electron microscopy (SEM), Raman spectroscopy and X-ray diffraction (XRD), while the surface chemistry was closely monitored by X-ray photoelectron spectroscopy (XPS). Thus, the incorporation of Cu1+ and In3+ into SnO2 lattice inducing the formation of oxygen vacancies combined with hydroxyl groups adsorbed on the outermost surface layer enhanced the sensitivity and selectivity of our sensing material. The sensors have been tested for NO2, CH4, CO, H2S target gases under humid air conditions very close to real working conditions. The sample with x =0.05mol% exhibits very attractive sensing properties for application as selective, low operating temperature (100°C), low cost H2S sensor. With a deeper understanding of the underlying mechanisms and further improvement of the synthesis one can foresee promising applications in catalysis.
      Graphical abstract image Highlights

      PubDate: 2014-07-28T17:46:59Z
       
  • Attempts to design porous carbon monoliths using porous concrete as a
           template
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Michael Taubert , Jens Beckmann , Andreas Lange , Dirk Enke , Olaf Klepel
      The preparation of carbon monoliths with defined shape and hierarchical pore system has been investigated. A template assisted route was applied using porous concrete as the template. The synthesis route was combined with a one pot chemical activation using phosphoric acid and zinc chloride, respectively, as the activating agents. As the template caused the formation of primary macropores the activation created a secondary system of micropores which resulted in a significant increase of the specific surface area up to about 1400m2 g−1. The material was characterized by means of mercury intrusion, helium pycnometry, and nitrogen adsorption at 77K.
      Graphical abstract image Highlights

      PubDate: 2014-07-28T17:46:59Z
       
  • Synthesis and characterization of metal oxides loaded-HZSM-5 and their
           implication for selective conversion of isopropanol
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Ibraheem O. Ali , Sahar A. El-Molla , Ibraheem A. Ibraheem , Tarek M. Salama
      A series of HZSM-5 catalysts containing Co(II), Ni(II) and Cu(II) were prepared by using the incipient wetness impregnation method. They were characterized by X-ray diffractometry (XRD), Fourier transform infra-red (FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and pore structure analysis by nitrogen adsorption at −196°C. The zeolitic samples have been tested as catalysts for the isopropanol conversion at 150–275°C. A significant structural collapse associated with disilication and dealumination of HZSM-5 took place upon treatment with Co(II), giving rise to Co3O4, Co2SiO4 and α-cristobalite silica crystalline multi phases. This fact is in fair agreement with the XPS spectra of this sample, thus the Co 2p3/2 signal at 779.7eV revealed the enrichment of Co(II) cations as oxide-like clusters in the outer layers of the crystals. The relevant components are absent in the XPS and XRD spectra of Ni/ and Cu/HZSM-5, so we assume that the extent of incorporation of Ni(II) and Cu(II) into the interconnecting pore system of HZSM-5 is almost complete. Cu/and Ni/HZSM-5 only exhibited IR bands at 3755 and 3735cm−1 ascribed to terminal silanol groups, respectively, due to the influence of the compensating cation. HZSM-5 and Cu/HZSM-5 have been proven to be the most active catalysts in isopropanol conversion, while Co/HZSM-5 is the least active one. Ni/and Cu/HZSM-5 gave 91% and 58% yields to acetone at 150°C, respectively, while Co/HZSM-5 and HZSM-5 led to 13% and 0.3%, respectively. HZSM-5 acted only as an active dehydration catalyst converting isopropanol to propylene. In contrast, Cu/and Ni/HZSM-5 served as dehydration and dehydrogenation catalysts yielding propylene as well as acetone, although at high isopropanol conversion only propylene is obtained.
      Graphical abstract image

      PubDate: 2014-07-28T17:46:59Z
       
  • Development of thioflavin-modified mesoporous silica framework for amyloid
           fishing
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Vivekanandan Viswanathan , Gopal Murali , Sakthivel Gandhi , Priyadharshini Kumaraswamy , Swaminathan Sethuraman , Uma Maheswari Krishnan
      Amyloid beta peptide accumulation in the brain poses a serious threat during Alzheimer’s disease. Various strategies to remove or disrupt these plaques with nanoparticles is an emerging area for the treatment for neurodegenerative diseases. The present work attempts to develop a novel strategy to remove the plaques using magnetic field by employing magnetic nanoparticles conjugated with a plaque-targeting ligand. Thioflavin-S (TF-S) was covalently linked to magnetic iron oxide incorporated mesoporous silica, SBA-15 and the material was characterized using microscopic and spectroscopic techniques. This magnetic conjugate (IO-SBA-TF-S) was found to display the ability to remove in vitro, KLVFF peptide, a recognition motif in β-amyloid that has been implicated in plaque formation. This system represents a potential smart system that could herald in the next generation therapeutic strategy for Alzheimer’s disease and related disorders.
      Graphical abstract image

      PubDate: 2014-07-28T17:46:59Z
       
  • A hydrothermal synthesis of a 2-dimensional layered silicate followed by a
           transition to a 3-dimensional aluminosilicate zeolite
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Anna Jackowski , Stacey I. Zones , Kaustav Chaudhuri , Howard S. Lacheen , Sheila W. Yeh
      We present a study of aluminosilicate zeolite synthesis where the first crystalline product observed is layered. It then transforms with time to the zeolite SSZ-81. The reaction has two crystalline phases that precede the SSZ-81 formation because FAU zeolite is used as the Al source that, eventually, is incorporated into the final organo-aluminosilicate zeolite product. The course of events is followed by microscopy, XRD, changes in solution pH, product organic mass, and TGA. In addition, the reaction using a chromium-exchanged FAU was performed that then allowed for tracking the same changes using EDX analyses in the SEM.
      Graphical abstract image

      PubDate: 2014-07-28T17:46:59Z
       
  • Molecular ordering of the discotic liquid crystal HAT6 confined in
           mesoporous solids
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Sylwia Całus , Andriy V. Kityk , Patrick Huber
      An optical polarimetry study of the orientational order of a discotic liquid crystal (DLC), 2,3,6,7,10,11-hexakis(hexyloxy)triphenylene (HAT6), confined into parallel-aligned cylindrical nanochannels of mesoporous alumina, silica, and silicon membranes as a function of temperature and channel radius (3.4–21.0nm) is presented. In contrast to the bulk state, the birefringence resulting from the confined discotic liquid crystal, exhibits a continuous temperature evolution and is positive indicating a dominating face-on (homeotropic) type molecular ordering with respect to the channel walls. Pronounced hysteresis effects observed in the experiment are traced to different nucleation sites of the low-temperature phase upon cooling and the high-temperature phase upon heating. Deviations from the Gibbs–Thomson scaling of the phase transition temperature for channel diameters below 10nm are traced to splay distortions of the confined liquid crystal.
      Graphical abstract image

      PubDate: 2014-07-28T17:46:59Z
       
  • Preparation of T-type zeolite membranes using a dip-coating seeding
           suspension containing colloidal SiO2
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Xuerui Wang , Zhanzhao Yang , Congli Yu , Liangwei Yin , Chun Zhang , Xuehong Gu
      T-type zeolite membranes were prepared on mullite tubes by the secondary growth method with a simple dip-coating seeding approach. Uniform and continuous seed layers were achieved by dip-coating with the addition of colloidal silica into the seed suspension. The seeded substrates could reproducibly induce high-performance T-type zeolite membranes at 378K for 30–35h. Typically, a water permeation flux of 1.22kg·m−2·h−1 with a separation factor of 2040 was obtained for pervaporation (PV) dehydration of 90wt.% ethanol/water mixture at 348K. T-type zeolite membranes with 80-cm lengths were successfully produced on a pilot scale. The as-synthesized membranes were further evaluated by ethanol dehydration. A formula for estimating the average water permeation flux was derived for a batch separation operation. Two membrane modules (0.1m2 for each) connected in series were continuously operated to dehydrate an industrial propanal solution with pH ∼4 for 1000h, which produced anhydrous propanal with a water content of <0.1wt.%.
      Graphical abstract image

      PubDate: 2014-07-28T17:46:59Z
       
  • Surface features and thermal stability of mesoporous Fe doped geoinspired
           synthetic chrysotile nanotubes
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): I.G. Lesci , G. Balducci , F. Pierini , F. Soavi , N. Roveri
      Synthetic mesoporous Fe doped geoinspired nanotubes have been utilized to evaluate the modification of the surface composition, morphology charge distribution and thermal stability as functions of the Fe doping extent and Fe prevalent substitution into the octahedral or tetrahedral sites. FTIR-ATR spectroscopy analysis has allowed to highlight the chrysotile structure modification by the Fe substitution to Mg or Si and to underline clearly the crucial role of the Fe doping in the octahedral sheet in modifying chrysotile structure and morphology. XPS analysis, ζ-potentials and porosity characterization have allowed to define the propriety of the chrysotile surface structure when iron replaces Mg in octahedral or Si in tetrahedral sites. DTA analysis has allowed to relate the effect of Fe doping on the chemical–physical characteristics of both synthetic and mineral chrysotile. We have observed that the simultaneous decrease in dehydroxylation and recrystallization temperature occurs when the Fe increases on surface and this is due to the increased substitution of Fe in octahedron. The results highlight the relevance to estimate the health hazard of the natural asbestos fibres by valuating the role of Fe surface throughout the use of geoinspired chrysotile synthesised under controlled stoichiometry and structure utilizing it as a selected reference standard.
      Graphical abstract image Highlights

      PubDate: 2014-07-28T17:46:59Z
       
  • Humidity sensing properties of Ag-loaded mesoporous silica SBA-15
           nanocomposites prepared via hydrothermal process
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Vijay K. Tomer , Parag V. Adhyapak , Surender Duhan , Imtiaz S. Mulla
      Ag nanoparticle loaded mesoporous silica SBA-15 nanocomposites have been synthesized by a facile hydrothermal route with (C2H5O)4Si in the presence of (AgNO3). Their response towards humidity has been studied. Low angle X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR), N2 adsorption-desorption, High Resolution Transmission Electron Microscopy (HRTEM), Scanning electron microscopy (SEM) and Energy Dispersive X-ray (EDX) spectroscopy techniques were utilized to characterize the composition and structure of the samples. In comparison with pure SBA-15, the Ag-loaded SBA-15 exhibits improved humidity response within the relative humidity (RH) range of 11–92%. The optimal result were obtained for 5wt% Ag-loaded SBA-15 sample, which demonstrate an excellent linearity, small hysteresis and high humidity sensitivity; moreover, it also exhibits satisfactory response and recovery time. The resistance shows change of more than 5 orders in magnitude over the entire humidity range. The mechanism for humidity sensing was studied. The investigation of humidity sensing characteristics of Ag-doped SBA-15 sensors indicates that the material has promising application as humidity sensor.
      Graphical abstract image Highlights

      PubDate: 2014-07-28T17:46:59Z
       
  • Biogenic amines in wine: Individual and competitive adsorption on a
           modified zirconium phosphate
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Z. Amghouz , C. Ancín-Azpilicueta , K.K. Burusco , J.R. García , S.A. Khainakov , A. Luquin , R. Nieto , J.J. Garrido
      A commercial zirconium phosphate was subjected to annealing in NaCl–NaOH aqueous solution until pH 3.2. The new material (Na-ZrP) and its n-butylamine intercalation product were characterized, among others, by powder X-ray diffraction, solid-state nuclear magnetic resonance, and high resolution transmission electron microscopy, being Na-ZrP a non-porous polyphasic semicrystalline material, constituted mainly of plate-shaped particles with domains of α-Zr(HPO4)2·H2O and α-Zr(NaPO4)(HPO4)·nH2O type. Na-ZrP was tested as an adsorbent for elimination of biogenic amines (histamine, putrescine, cadaverine, and tyramine) in synthetic wine. Among the studied amines, histamine is the fastest adsorbed (individually and competitively), followed by cadaverine, putrescine and tyramine. All of them present L2-type individual isotherms. Competitive isotherms are also L2-type except cadaverine (L-Max) and tyraminte (Type C). Histamine and putrescine are the amines absorbed in higher amounts. The results from adsorption isotherms and kinetic measurements (individual and competitive) fit the adsorption classical models showing that the preferential adsorption mechanism is the ion-exchange of the cationic amines with Na+ cations present in the adsorbent, being not discarded that some amines could be joined by hydrogen bonds.
      Graphical abstract image Highlights

      PubDate: 2014-07-28T17:46:59Z
       
  • Synthesis of lightweight polymer-reinforced silica aerogels with improved
           mechanical and thermal insulation properties for space applications
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Hajar Maleki , Luisa Durães , António Portugal
      Cross-linking of silica aerogels with organic polymers is an effective way to overcome their fragility and poor mechanical properties. It has also been shown that adjusting the nanoskeleton of silica aerogels using different silica precursors can lead to improved mechanical properties, mesoporosity and thermal conductivity. In this paper, the effect of the incorporation of 1,6-bis(trimethoxysilyl)hexane (BTMSH) and 1,4-bis(triethoxysilyl)-benzene (BTESB) into the underlying silica structure of tri-methacrylate cross-linked silica aerogels is examined. In order to attain a simple, cost and time effective procedure, the sol–gel process and addition of organic monomers are performed in one single step. The effect of the amount of silicon derived from alkyl-linked and aryl-linked bis-silane precursors as well as the effect of the cross-linker concentration on the mechanical strength, thermal conductivity, porosity and other properties of the synthesized aerogels are studied. Different reinforced silica aerogels with density range from 0.13 to 0.39gcm−3, compression strength from 11 to 400kPa and thermal conductivity of 0.039–0.093Wm−1 K−1 were obtained. The cross-linked aerogels made by replacing 5–10mol% of total silicon by BTESB showed a drastic improvement in their surface area and thermal insulation properties along with an increase in the mechanical strength. The surface area and thermal insulation improvements obtained for aryl-bridged polysiloxanes were attributed to the aryl spacer within the aerogels body, which leads to aerogel with high extent of porosity or pore volume when compared to the alkyl-bridged polysiloxanes. Therefore, for the first time we were able to show the dependency of thermal conductivity values on the silica structure by proper designing the mesoporosity of the resulting aerogels.
      Graphical abstract image

      PubDate: 2014-07-28T17:46:59Z
       
  • Synthesis of ordered mesoporous carbons with tunable pore size by varying
           carbon precursors via soft-template method
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Qiaowei Wang , Weili Zhang , Yijie Mu , Liangshu Zhong , Yan Meng , Yuhan Sun
      Ordered mesoporous carbons (OMCs) with tunable pore size in the range of 3.6–6.2nm were prepared using the mixture of phenol, resorcinol and phloroglucinol as carbon precursor and triblock copolymer F127 as template via self-assembly method. The OMCs had ordered 2-D hexagonal mesostructure with high specific surface areas (up to 1100m2/g) and pore volume (up to 0.84cm3/g). Nitrogen sorption results demonstrated that the pore size of OMCs can be tuned by varying the composition of carbon precursors and the mass ratio of carbon precursor-to-F127. Systematic research revealed that increasing amount of resorcinol and phloroglucinol in carbon precursors resulted in carbons with larger pore size but less ordered mesostructure. Compared with resorcinol, phloroglucinol facilitated a larger mesopore, while led to a worse mesostructure.
      Graphical abstract image Highlights

      PubDate: 2014-07-28T17:46:59Z
       
  • One-pot synthesis of aldehyde-functionalized mesoporous silica-Fe3O4
           nanocomposites for immobilization of penicillin G acylase
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Ling Yang , Yanglong Guo , Wangcheng Zhan , Yun Guo , Yunsong Wang , Guanzhong Lu
      Aldehyde-functionalized mesoporous silica-Fe3O4 nanocomposites, one-pot synthesized by co-condensation of tetraethylorthosilicate and trimethoxysilylpropanal in presence of triblock copolymer of Pluronic P123, NaCl and Fe3O4 nanoparticles in the neutral solution, were characterized by SAXS, XRD, TEM, nitrogen sorption, FT-IR, TG, elementary analysis and magnetic susceptibility measurements, and investigated as the supports for covalent immobilization of penicillin G acylase (PGA). The results show that paramagnetic Fe3O4 nanoparticles were embedded among the cannular mesoporous silica layers and the aldehyde groups were condensed on the surface of mesoporous silica. PGA was covalently immobilized on these paramagnetic nanocomposites via the reaction to produce Schiff’s base between the free amino groups of lysine residues of PGA and the aldehyde groups on the surface of these nanocomposites. PGA immobilized on these paramagnetic nanocomposites had better operational stability and was easily recycled by an external magnetic field. The immobilized PGA had the initial activity of 6231Ug−1 and the operational stability of 91.0% of the initial activity after recycled for 10 times.
      Graphical abstract image Highlights

      PubDate: 2014-07-28T17:46:59Z
       
  • Enhancement of synthesis of ZSM-11 zeolite by microwave irradiation
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Federico Azzolina Jury , Isabelle Polaert , Lionel Estel , Liliana B. Pierella
      A novel and complete description for ZSM-11 zeolite microwave-assisted synthesis is provided. The time required for the synthesis of ZSM-11 zeolite was remarkably reduced down to 3–4days instead of 14days under classical conditions, without the use of seed crystals and of any pretreatment step such as aging time. The crystallinity degree of ZSM-11 zeolites synthesized under microwave irradiation is considerably improved (39% higher) with respect to the crystallinity of conventional ZSM-11 zeolites. According to SEM images, the particle sizes of ZSM-11 zeolites synthesized by both methods are identical and a new morphology is observed when microwave irradiation is used. The surface area and microporous volume values for both synthesis methods are similar. In this work, the synthesis of ZSM-11 zeolite has been successfully intensified by using microwave irradiation. Energy consumption and synthesis time are considerably reduced.
      Graphical abstract image Highlights

      PubDate: 2014-07-28T17:46:59Z
       
  • Modified nanocrystalline natural zeolite for adsorption of arsenate from
           wastewater: Isotherm and kinetic studies
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Meissam Noroozifar , Mozhgan Khorasani-Motlagh , Hamidreza Naderpour
      This work investigates the efficiency and possibility of modified nanoscale zeolite with baloform for removing of arsenate anions from wastewaters. A combination of scanning electron microscopy, X-ray diffraction, Fourier transform-infrared spectroscopy, Thermogravimetric-differential thermal analysis and Brunauer–Emmett–Teller surface area were used for characterization of zeolitic materials. Effects of different parameters such as pH and dosage of adsorbent, on the arsenate removing yield are studied. The yield of arsenate removing increases by increasing dosage of adsorbent and contact time. The results show that arsenate removal efficiency from wastewaters is higher than 99% at optimum conditions. The adsorption data of the modified zeolite for arsenate removing was consistent with six isotherm equations (Freundlich, Langmuir, Langmuir–Freundlich, Dubinin–Radushkevich, Redlich–Peterson and Toth). The obtained modeling results indicated that, although the three-parameter models, taking into account the surface heterogeneity, provided the closest approach to the measurement data, the parameters estimates could be highly biased. Batch experiments were carried out to study the removal kinetics of arsenate. The kinetic studies proved that the Elovich was the applicable model.
      Graphical abstract image

      PubDate: 2014-07-28T17:46:59Z
       
  • Exploration of room temperature synthesis of palladium containing cubic
           MCM-48 mesoporous materials
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Harrison S. Kibombo , Vagulejan Balasanthiran , Chia-Ming Wu , Rui Peng , Ranjit T. Koodali
      Pd-MCM-48 mesoporous materials were synthesized by a modified Stöber synthesis method in 4h at room temperature. Pd nanoparticles were prepared by using Na2[PdCl4] and Pd(acac)2 as Pd precursors, and their influence in the preparation of the cubic MCM-48 mesoporous phase was investigated. In addition, Pd(0) nanoparticles was prepared separately and added to the synthesis gel. The influence of varying the Pd precursor, solvent media, the time of addition of Pd precursor, and the concentration of NaBH4 reducing agent used for preparation of Pd(0) and its effect for the formation of the cubic phase were investigated. These resultant materials were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), UV–Visible spectroscopy, nitrogen physisorption, and CO-Pulse titration. Reusability studies assessing a material prepared using Pd(0)-DMAP encapsulated nanoparticles that were reduced with 0.1N NaBH4 i.e. 3%Pd-MCM-48-D-N01 indicate that the yields for the hydrogenation of trans-cinnamic acid are greater than 95% even after 8 catalytic cycles, and at which the cubic phase was maintained under our experimental conditions.
      Graphical abstract image

      PubDate: 2014-07-28T17:46:59Z
       
  • Subcritically dried resorcinol–formaldehyde aerogels from a
           base–acid catalyzed synthesis route
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Jessica Laskowski , Barbara Milow , Lorenz Ratke
      Resorcinol–formaldehyde (RF) aerogels are prepared from a newly developed base–acid catalyzed sol–gel synthesis route. RF-gels synthesized are nanostructured and can be dried under ambient conditions without significant shrinkage. The sol–gel reaction of resorcinol (R) and formaldehyde (F) in water (W) (R/F=0.7, R/W=0.04) is initially catalyzed by Na2CO3 with a molar ratio of resorcinol to catalyst (R/C) of 100. After a specified time after starting the reaction (1–3h), citric acid (1M, 4–20vol.%) is added which initiates the acid catalyzed step and causes a spontaneous gelation. The time of change in pH value by adding acid is of great importance and influences the structure and properties of the material. RF-aerogels consisting of small particles much smaller than 100nm are prepared by applying a long base catalyzed step. Particle size, density, thermal conductivity and surface area are basically independent of the amount of citric acid, but this parameter influences the mechanical resistance. A theoretical model is used to describe the time dependence of catalyst change in the sol–gel process.
      Graphical abstract image

      PubDate: 2014-07-28T17:46:59Z
       
  • The synthesis and characterization of high purity mixed
           microporous/mesoporous activated carbon from rice husk using chemical
           activation with NaOH and KOH
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Lingeswarran Muniandy , Farook Adam , Abdul Rahman Mohamed , Eng-Poh Ng
      Activated carbon (AC) with high purity and surface area was synthesized from rice husk (RH) using alkali leaching at room temperature. Regular and pyridine FT-IR analysis had shown that the AC sample consists mainly of CC aromatic bonds and did not have Brønsted or Lewis acid sites respectively. In addition, the XRD patterns indicate that all AC samples were amorphous with slight micro-crystalline features due to the appearance of broad peaks at 2θ =24° and 44° respectively. The maximum surface area obtained from the BET analysis was 2696m2 g−1 for the KOH activated carbon at 850°C with an impregnation ratio of 1:5 (RHC:KOH) under nitrogen flow. The SEM images also revealed the highly porous nature of the AC resulting in the high surface area. The TGA-DTG analysis of the AC samples showed that the samples are thermally stable up to 900°C in nitrogen atmosphere.
      Graphical abstract image Highlights

      PubDate: 2014-07-28T17:46:59Z
       
  • Pd nanoparticles immobilized in a microporous/mesoporous composite
           ZIF-8/MSS: A multifunctional catalyst for the hydrogenation of alkenes
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Tong Zhang , Bo Li , Xiongfu Zhang , Jieshan Qiu , Wei Han , King Lun Yeung
      The work reports a new hierarchically core–shell structure that consists of a catalytically active core made of palladium–decorated mesoporous silica spheres (Pd/MSS) and an outer shell of microporous ZIF-8. The synthesis process involves (i) the preparation of MSS via supramolecular templating using a modified Stöber method, (ii) the loading of palladium nanoparticles into MSS, followed by (iii) the surface modification of Pd/MSS catalyst with polyelectrolyte to promote the nucleation and growth of a ZIF-8 shell. The core–shell Pd/MSS@ZIF-8 was characterized by X-ray diffraction, electron microscopy (SEM & TEM), FTIR, ICP-AES and N2 physisorption to determine its physicochemical properties. The core–shell Pd/MSS@ZIF-8 was used to catalyze the hydrogenation of 1-hexene and cyclohexene. Results showed that the Pd/MSS@ZIF-8 was a multifunctional catalyst with excellent reactant shape-selectivity, leaching-proof ability, improved poison resistance and good recyclability in contrast to the conventional Pd/MSS catalyst.
      Graphical abstract image

      PubDate: 2014-07-28T17:46:59Z
       
  • Mesoporous silica based novel conjugate adsorbent for efficient
           selenium(IV) detection and removal from water
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Md. Rabiul Awual , Md. Munjur Hasan , Toshihiro Ihara , Tsuyoshi Yaita
      Selenium is a very toxic element that at low concentration can affect human beings and living organisms. In this study, the ligand immobilized conjugate adsorbent was developed and selenium (Se(IV)) detection and removal from water were investigated. The conjugate adsorbent was successfully prepared by direct immobilization of 6-((2-(2-hydroxy-1 naphthoyl)hydrazono) methyl)benzoic acid onto mesoporous inorganic silica. This study was performed to evaluate the several influencing parameters such as solution pH, contact time, initial concentration, and the presence of competitive ions on the monitoring and removal performance. The adsorbent has the specific functionality for Se(IV) detection and removal from aqueous media. Moreover, the adsorbent has large surface area-to-volume ratios and uniformly mesostructures shaped pores that were actively working to capture Se(IV). The point of zero charge of the adsorbent was evaluated to understand the adsorption phenomenon. The limit of detection of the method presented was 2.16ppb at optimum conditions. The adsorption data were well interpreted by the Langmuir adsorption isotherm and the maximum adsorption capacity was 103.73mg/g. The adsorbent was capable of Se(IV) removal even in the presence of a high amount of coexisting cations and anions such as sodium, potassium, calcium, chloride, nitrate, sulfate, phosphate and etc. This technique achieved residual Se(IV) concentration less than 10ppb, which is acceptable by water quality regulations. The adsorbed Se(IV) was eluted with 0.10M NaOH and simultaneously regenerated into the initial form for the next operation after rinsing with water. Moreover, the adsorbent was retaining functionality in spite of several cycles during sorption–elution–regeneration operations. Therefore, the solid design adsorbent is efficient and cost-effective for selective Se(IV) detection and removal from water.
      Graphical abstract image Highlights

      PubDate: 2014-07-28T17:46:59Z
       
  • Fast and efficient optimization of Molecular Dynamics force fields for
           microporous materials: Bonded interactions via force matching
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Andrea Gabrieli , Marco Sant , Pierfranco Demontis , Giuseppe B. Suffritti
      A fast and efficient implementation of the force matching technique is presented and effectively applied to two important members of the microporous family. It enables the development of classical Molecular Dynamics force fields, tailored to each specific structure, starting from detailed ab-initio data. Reliable bonded interaction constants have been obtained for systems of increasing complexity, namely: CH4, CO2, Silicalite, and ZIF-8. The quality of the resulting parametrizations has been assessed, comparing model and reference vibrational spectra.
      Graphical abstract image

      PubDate: 2014-07-28T17:46:59Z
       
  • Combined experimental and theoretical investigation on photophysical
           properties of trans-azobenzene confined in LTL zeolite: Effect of
           cis-isomer forming
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197
      Author(s): Wilaiporn Insuwan , Kunwadee Rangsriwatananon , Jittima Meeprasert , Supawadee Namuangruk , Yaowarat Surakhot , Nawee Kungwan , Siriporn Jungsuttiwong
      The spectroscopic methods and molecular modeling were employed to study the photophysical properties of t-azobenzene in solution and in the channel of zeolite LTL. The effects of the interactions between the dye molecules and zeolite framework on the electronic states were examined experimentally by diffuse reflectance UV–visible absorption and fluorescence emission. The changes observed in the spectra were dependent on the forms of zeolite LTL (H-LTL and K-LTL). In addition the structural properties of the dye in the different environments were also intensively investigated by density functional theory (DFT) calculations with B3LYP/6-31G(d,p) level of theory. The 324T cluster model and the ONIOM (B3LYP/6-31G(d,p):UFF) methods were employed for the calculating the orientations of the dye in the zeolite system. The experimental data are consistent with the calculation results. The dye in solution can be relaxed into the planar structure, however, when the dye is in LTL zeolite it is constrained by the framework and is therefore twisted due to the confinement effects of zeolite. Moreover, emission spectra were detected only from protonated t-azobenzene incorporated into H-LTL while no emission was detected from t-azobenzene confined in K-LTL framework. The results of the study lead to the conclusion that the zeolite framework affects both the structural and photophysical properties of t-azobenzene.
      Graphical abstract image Highlights The spectroscopic methods and molecular modeling were employed to study the photophysical properties of t-azobenzene in the channel of zeolite LTL. The trans-isomer can be isomerized to the cis-isomer with the confinement effect in zeolite channel.

      PubDate: 2014-07-28T17:46:59Z
       
  • Editorial Board
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196




      PubDate: 2014-07-28T17:46:59Z
       
  • Para-selective methylation of toluene with methanol over nano-sized ZSM-5
           catalysts: Synergistic effects of surface modifications with SiO2, P2O5
           and MgO
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Wei Tan , Min Liu , Yan Zhao , Keke Hou , Hongyu Wu , Anfeng Zhang , Haiou Liu , Yiren Wang , Chunshan Song , Xinwen Guo
      The nano-sized ZSM-5 catalysts were modified by surface coating with SiO2, P2O5, MgO and their combinations; the catalytic properties were investigated in the shape-selective methylation of toluene with methanol. The catalysts were characterized by XRD, XRF, N2 adsorption–desorption, temperature programmed desorption of ammonia (NH3-TPD), Fourier-transform infrared spectra of adsorbed pyridine/2,6-di-tert-butylpyridine, and adsorption of n-hexane/cyclohexane. The passivation of Lewis acid sites occurs prior to that of the Brönsted acid sites over ZSM-5 modified by SiO2, while P2O5 or MgO preferentially neutralizes the Brönsted acid sites of ZSM-5. The deposition of MgO is more efficient in passivating the acid sites and narrowing the pore openings, compared to SiO2 or P2O5 modification with the same oxide content (<9wt%). The single modification could not completely passivate the external surface acid sites and simultaneously narrow the pore openings to a proper extent; so the selectivity to para-xylene does not exceed 90% even at the highest oxide loading. The multiple modification by SiO2, P2O5 and MgO, with a suitable sequence can efficiently eliminate external surface acid sites, and simultaneously narrow the pore openings, which led to a higher para-selectivity (∼98%). The combined modification with SiO2, P2O5 and MgO in a proper sequence can lead to a synergistic effect for tailoring the acid property and pore mouth of the catalyst, thus enhancing the para-selectivity to ∼98% and improving catalytic stability, as demonstrated by flow test for 1000h on stream.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:57:01Z
       
  • A new hierarchical porous zirconium phosphate membrane and its adsorption
           properties
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Abubaker Abutartour , Yunjie Jia , Lotfia El Majdoub , Qinghong Xu
      A hierarchical porous zirconium phosphate membrane was prepared from bis(hexamethylenetriaminepenta(methylenephosphonic acid)), ZrOCl2·8H2O, SiF4 and hexadecyl trimethyl ammonium bromide. The membrane contains macropores of 200nm in diameter, and mesopores of 19.2nm in diameter. The membranes pores were bridged and limited by (–Si–O–) n edges. The porous membrane exhibited high efficiency in removing Pb2+ and Cu2+ from wastewater.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:57:01Z
       
  • Chemical activation of tannin-based hydrogels by soaking in KOH and NaOH
           solutions
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): A. Szczurek , G. Amaral-Labat , V. Fierro , A. Pizzi , A. Celzard
      Tannin–formaldehyde hydrogels prepared at different pH were chemically activated in an unusual way. Instead of impregnating dry organic or carbon gels, fresh hydrogels were indeed used as such, i.e. in the wet state. The water contained in their porosity was simply exchanged by NaOH or KOH aqueous solutions having various concentrations. The impregnated gels were thus vacuum-dried, leading to xerogels in which the alkali was extremely well dispersed inside, and then heat-treated at 750°C. The resultant activated carbon gels were characterised, and the effects of initial pH, concentration and nature of the hydroxide were discussed. The present way of activating the gels produced homogeneous materials with a foam-like structure presenting high surface areas and micropore volumes even when very low hydroxide amounts were used.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:57:01Z
       
 
 
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