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PHYSICS (537 journals)            First | 1 2 3 4 5 6 | Last

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: 2)
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: 16)
Materials Science     Hybrid Journal   (Followers: 7)
Materials Science and Engineering: A     Hybrid Journal   (Followers: 31)
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)
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: 41)
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: 10)
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)
Particuology     Hybrid Journal  
Pattern Recognition in Physics     Open Access   (Followers: 1)
Pergamon Materials Series     Full-text available via subscription  
Phase Transitions and Critical Phenomena     Full-text available via subscription   (Followers: 1)
Philosophical Magazine     Hybrid Journal   (Followers: 2)
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences     Full-text available via subscription   (Followers: 5)
Philosophy and Foundations of Physics     Full-text available via subscription  

  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]
  • Synthesis of ZIF-8 from recycled mother liquors
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Nilay Keser Demir , Berna Topuz , Levent Yilmaz , Halil Kalipcilar
      The effect of the methanol/Zn(NO3)2 molar ratio on the particle size, BET surface area and on the rate of the crystallization have been studied. The use of excess methanol leads to a decrease in particle size and rate of crystallization. Crystals grown from solutions with methanol/Zn(NO3)2 molar ratios of 1043 and 87 are 60 and 600nm based on SEM images, respectively. A systematic study was also conducted in which mother liquor recovered from the synthesis of ZIF-8 was used to produce second, third and even fourth generations of ZIF-8 crystals. Crystals produced from recycled solutions have similar morphology, BET surface area and thermal stability from the population crystallized by the fresh solution. The incorporation of NaOH and Zn(NO3)2 to the recycled mother liquor initiated the nucleation and stimulated the crystal growth. This approach enabled a substantial rise in the yield of nanosize ZIF-8. The ZIF-8 yield was about 38% during the synthesis from fresh solution, whereas the total yield rose to about 80% by recycling. From an environmental perspective, this process is very favorable since the recycle of the mother liquor minimizes the amount of waste produced during the synthesis of ZIF-8.
      Graphical abstract image

      PubDate: 2014-08-15T18:59:15Z
       
  • Unique polyvinyl acetate–mesoporous synthetic zeolite composites
           prepared in ultrasonic field
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Anita-Laura Radu , Celina Damian , Victor Fruth , Tanta-Verona Iordache , Anamaria Zaharia , Horia Iovu , Andrei Sarbu
      The host–guest radical polymerization of vinyl acetate in the inorganic porous matrix improved both, thermal and mechanical properties of final modified material, relative to the polymer alone, which can be further used for various applications where stability in aggressive environments is required. The bulk material was characterized by various techniques i.e. elemental analysis, X-ray photoelectron spectroscopy (XPS), gel permeation chromatography (GPC), thermal gravimetric analysis (TGA), dynamic mechanical analysis (DMA), scanning electron microscopy (SEM) and porosity measurements (BET). XPS measurements indicated a preferential order of acetate groups at the surface of the hybrid and BET analyses highlighted the formation of a new porous structure derived from the mesoporous inorganic host. GPC results of the polymer extracted from the zeolite matrix showed variations of molecular weight and low polydispersity index relative to the pure polymer, which could be a consequence of a controlled polymerization mechanism induced by the presence of metal ions found in the zeolite matrix. Thermal stability and elasticity of the restrained polymer compared to that of pure PVAc was notably enhanced. Char formation in the sixth degradation stage and demethylation were additional steps compared to PVAc alone indicating some modifications of the thermal degradation mechanism for the entrapped PVAc.
      Graphical abstract image

      PubDate: 2014-08-15T18:59:15Z
       
  • Facile synthesis of ordered mesoporous Cu-ZrPO with high copper contents
           as catalyst for liquid phase oxidation of ethylbenzene
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Zhichao Miao , Huahua Zhao , Jian Yang , Jun Zhao , Huanling Song , Lingjun Chou
      A series of mesoporous Cu-ZrPO (M-Cu-ZrPO) materials with high specific surface area (∼200m2 g−1), large pore volume (∼0.4cm3 g−1), uniform pore size (∼7.8nm) and various copper contents in a wide range (0–40%) were successfully synthesized via a facile one-pot evaporation induced self-assembly (EISA) strategy. Different characterization techniques, XRD, N2-physisorption, TEM, TG-DSC, UV–vis spectra and H2-TPR were employed to investigate the mesoporous structure and copper states. The ordered mesostructure was improved with the introduction of copper species and could be successfully maintained even at a copper content up to 30%, in which the copper species were highly dispersed in the skeleton of mesostructure. Additionally, M-Cu-ZrPO exhibited excellent thermal stability and the ordered mesostructure could be successfully preserved even after treating at 700°C. Moreover, M-Cu-ZrPO was employed as catalyst for liquid phase oxidation of ethylbenzene. On account of the advantageous mesoporous structure and highly dispersed copper species, the catalytic performance of M-Cu-ZrPO was gradually improved with the increasing of copper contents and achieved the maximum at 30% copper content with 91.2% conversion of ethylbenzene and 87.0% selectivity of acetophenone. In addition, M-Cu-ZrPO showed excellent stability and reusability even after five cycles.
      Graphical abstract image

      PubDate: 2014-08-15T18:59:15Z
       
  • Simultaneous surface and pore structure modification for growth of ZIF-8
           membranes on coarse macroporous tube
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Jianhua Yang , Zhong Xie , Huimin Yin , Jinqu Wang , Jing Xu , Jingjing Wang , Jinming Lu , Dehong Yin , Yan Zhang
      Here we report a modified “two in one” strategy through depositing of ZnO particles onto the macroporous α-alumina tubes with average pore size of 2–3μm for synthesis of ZIF-8 membranes. The LTA or Al2O3 particles as fillers were firstly deposited to patch the large defects in the support then the ZnO particles were deposited. The ZnO particles reduce the pore size and simultaneously act as “metal source” to create a high supersaturation degree to promote high heterogeneous nucleation sites. Through such strategy, continuous and crack-free ZIF-8 membranes were successfully obtained, exhibiting H2 permeance of 3.4×10−7 molm−2 s−1 Pa−1 at 150°C, with ideal selectivities for H2/CO2, H2/N2, H2/CH4 and H2/C3H8 system of 7.4, 8.8, 8.2 and 37.8, respectively. When the supports deposited with ZnO particles were treated by pre-reacting with the ligand of 2-methylimidazole, big cracks/gaps occurred at the interface between the ZIF-8 membranes and the supports. This modified “two in one” strategy can be extended for synthesis of large variety of MOFs membranes on large-pore supports through the rational selection of metal oxides.
      Graphical abstract image Highlights

      PubDate: 2014-08-15T18:59:15Z
       
  • New method for preparation of delivery systems of poorly soluble drugs on
           the basis of functionalized mesoporous MCM-41 nanoparticles
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): M. Popova , A. Szegedi , K. Yoncheva , S. Konstantinov , G.P. Petrova , H.A. Aleksandrov , G.N. Vayssilov , P. Shestakova
      MCM-41 silica with spherical morphology and small particle sizes (100nm) was synthesized and modified by post-synthesis method with amino and/or carboxylic groups. Solid state reaction was applied for the first time for loading of poorly soluble drug mesalazine (5-aminosalicylic acid – 5-ASA). The non-loaded and drug loaded mesoporous silicas were characterized by XRD, TEM, N2 physisorption, elemental analysis, thermal analysis, FT-IR and solid state NMR spectroscopy. Quantum-chemical calculations were used to predict the interactions between the drug molecule and the functional groups of the carrier. The nanoparticles were post-coated with sodium alginate and the coating modified the rate of mesalazine release from MCM-41NH2 and MCM-41NH2COOH particles. Cytotoxic evaluation on colon adenocarcinoma cell line revealed that the alginate coating reduced cytotoxicity of mesalazine loaded in the post-coated particles compared to the pure mesalazine. The functionalized, polymer coated mesoporous systems are suitable oral drug delivery systems providing an opportunity to modify drug release.
      Graphical abstract image

      PubDate: 2014-08-15T18:59:15Z
       
  • Comparison of the catalytic benzene oxidation activity of mesoporous ceria
           prepared via hard-template and soft-template
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Yihong Ke , Suk-Yin Lai
      Mesoporous ceria samples were prepared both by nanocasting using SBA-15 mesoporous silica as hard-template and by evaporation-induced self-assembly using F127 triblock copolymer as soft-template. The samples were characterized by TEM, XRD, TPR, XPS and nitrogen adsorption. Ceria prepared with hard-template appeared as arrays of connected rods with high specific surface area and highly defective internal structure that facilitates bulk reduction by hydrogen at temperature as low as 400°C. The soft-template made sample exhibited morphology of three dimensionally linked filaments with low extent of internal defects. Hydrogen reduction of the soft-template made ceria was confined to the surface region for reduction temperature as high as 700°C. The hard-template made ceria was much more active than the soft-template made ceria for benzene oxidation at low temperature, giving a T 50 at 257°C. The activity of the soft-template made ceria was greatly enhanced by etching with 2M NaOH at 80°C overnight. The high benzene oxidation activity of both the hard-template made and the sodium hydroxide treated soft-template made ceria were attributed to the generation of surface defects by the action of sodium hydroxide. The defect sites adsorb active oxygen that effect benzene oxidation below 300°C.
      Graphical abstract image

      PubDate: 2014-08-15T18:59:15Z
       
  • Separation of CO2/CH4 and CH4/N2 mixtures by M/DOBDC: A detailed dynamic
           comparison with MIL-100(Cr) and activated carbon
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Libo Li , Jiangfeng Yang , Junmin Li , Yang Chen , Jinping Li
      In this report we studied the gas adsorption and breakthrough characteristics of M/DOBDC (M=Mg, Co, or Ni) metal–organic frameworks, with honeycomb-like structures and high concentrations of coordinatively unsaturated sites. We studied these characteristics by using M/DOBDC to separate CO2/CH4 and CH4/N2 mixtures and compared those results to separation using MIL-100(Cr) and activated carbon, particularly focusing on the adsorption capacities and equilibrium times. We show that the presence of coordinatively unsaturated sites greatly influences gas adsorption, separation, and regeneration. Mg/DOBDC displayed excellent separation efficiency for CO2/CH4 and simple regeneration under dynamic conditions, while Ni/DOBDC had superior CH4/N2 adsorption selectivity and CH4/N2 separation and exhibited strong interactions between CH4 molecules and its coordinatively unsaturated Ni atoms. Overall, the M/DOBDC frameworks demonstrated extremely high capacity, high selectivity, and easy regeneration for CO2 and CH4 separation under dynamic conditions, making them suitable for gas separation.
      Graphical abstract image

      PubDate: 2014-08-15T18:59:15Z
       
  • Role of fluoride ions in synthesis and isomerization performance of
           superfine SAPO-11 zeolite
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Yuxiang Liu , Xiao Cui , Lei Han , Zhiwu Yu , Xinmei Liu
      In presence of fluoride ions, superfine silico-alumino-phosphate-11 zeolite was synthesized via steam-assisted conversion method. The samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen sorption, pyridine adsorption Fourier transform infrared spectroscopy, magic angle spinning nuclear magnetic resonance spectroscopy and dynamic light scattering techniques. The results show that the fluoride ions decrease particle size and induce inorganic species to achieve oriented growth. The resulting rod-like SAPO-11 crystalline particles are 500nm in length and acid sites are controlled by mass ratio of fluoride ions in the initial gel. The catalytic isomerization of superfine SAPO-11 was evaluated using n-dodecane and vacuum gas oil as feed streams. The catalysts with SAPO-11 promoter exhibit more iso-hydrocarbon in the gasoline compared to catalysts without promoter. Of note is the higher coke resistant ability of catalyst with SAPO-11 due to high electronegativity of fluoride ions. Desorption of coke precursor is easier from catalyst with promoter than that without promoter. The role of fluoride ions is to inhibit coke deposition by suppressing condensation reactions.
      Graphical abstract image

      PubDate: 2014-08-15T18:59:15Z
       
  • Three-dimensional ordered mesoporous carbon nitride with large mesopores:
           Synthesis and application towards base catalysis
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Jie Xu , Fei Wu , Hai-Tao Wu , Bing Xue , Yong-Xin Li , Yong Cao
      Mesoporous g-CN material has been prepared by using FDU-12 as a template, and carbon tetrachloride and ethylenediamine as precursors via a nanocasting method. Small angle X-ray scattering and transmission electron microscopy confirm that the synthesized CN-FDU-12 possesses well-ordered mesostructures and faithfully replicates the face-centered cubic symmetry of FDU-12. The surface area and pore volume acquired in CN-FDU-12 are 702m2 g−1 and 1.4cm3 g−1, respectively, along with large pore size of 7.5nm. Fourier transform infrared and X-ray photoelectron spectra reveal that the motifs of CN-FDU-12 are pyridine rings interconnected by tertiary N atoms. As a heterogeneous base catalyst, CN-FDU-12 demonstrates high and steady activity in the transesterification of ethylacetoacetate with a series of alcohols. Moreover, the catalytic activity achieved over CN-FDU-12 is superior to those obtained over other mesoporous g-CN materials templated by SBA-15 and MCF. The excellent performance is attributed to the high percentage of tertiary N species in CN-FDU-12. Accordingly, a possible reaction mechanism for the transesterification of β-keto esters has been proposed.
      Graphical abstract image Highlights

      PubDate: 2014-08-15T18:59:15Z
       
  • Ru supported on zirconia-modified SBA-15 for selective conversion of
           cellobiose to hexitols
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Yufei Niu , Hua Wang , Xinli Zhu , Zhiqiang Song , Xianna Xie , Xiao Liu , Jinyu Han , Qingfeng Ge
      Ru supported on zirconia-modified SBA-15 as a catalyst for selective conversion of cellobiose has been prepared and characterized using X-ray diffraction, N2 adsorption, transmission electron microscopy, and temperature programmed desorption of NH3. Coating SBA-15 with zirconia generates acid sites as well as improves Ru dispersion in the mesopore. At a Zr/Si ratio of 0.25 (∼1.4 monolayer coverage of zirconia on the SBA-15 surface), the mesoporous structure of SBA-15 was well preserved in zirconia-modified SBA-15. Increasing the amount of zirconia beyond Zr/Si=0.5 resulted in narrowing of the mesopores and, eventually, pore blockage. Mechanistic study of cellobiose conversion on the catalyst indicates that the reaction proceeds sequentially through (a) hydrogenolysis/hydrogenation of cellobiose to 3-β-d-glucopyranosyl-d-glucitol, (b) hydrolysis to sorbitol and glucose, and (c) glucose hydrogenation to hexitols, with the hydrolysis step being the rate-determining step for hexitols formation. A complete conversion of cellobiose with a hexitols yield of 72% has been achieved at 140°C in 1h with the optimal Zr/Si ratio of 0.25. A comparison with the more acidic Ru/HZSM-5 catalyst demonstrated the importance of the mesopores of SBA-15 to the catalytic reactivity of Ru/Zr-SBA-15(0.25).
      Graphical abstract image

      PubDate: 2014-08-15T18:59:15Z
       
  • High-pressure behavior of davyne [CAN-topology]: An in situ single-crystal
           synchrotron diffraction study
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Paolo Lotti , G. Diego Gatta , Marco Merlini , Michael Hanfland
      The high-pressure elastic behavior and the pressure-induced structural evolution of a natural P63/m davyne was investigated by in situ single-crystal synchrotron diffraction with a diamond anvil cell. A P-induced displacive phase transition from a P63/m to a P63 structure occurred between room-P and 0.38(2)GPa. The post-transition P63-davyne showed a large isothermal (293K) stability field as function of pressure, being stable at least up to 7.18(2)GPa. The elastic behavior was described by a III-order Birch–Murnaghan equation of state fit, leading to the following refined elastic parameters: V 0 =761.6(5)Å3, K V 0 = 46.5 ( 11 ) GPa and K V ′ = 3.7 ( 3 ) ; a 0 =12.814(2)Å, K a 0 = 50.3 ( 9 ) GPa and K a ′ = 4.0 ( 3 ) ; c 0 =5.3561(9)Å, K c 0 = 40.3 ( 7 ) GPa and K c ′ = 3.2 ( 2 ) . The refined isothermal volume bulk modulus (46.5(3)GPa) is comparable to those so far reported for other cancrinite-group compounds. The elastic anisotropy at room-P conditions can be described as K a 0 : K c 0 = 1.25 : 1 , and was found to increase with pressure. The bulk volume compression is mainly accommodated by the tilting of the quasi-rigid framework tetrahedra. A description of the P-induced deformation mechanisms at the atomic scale and a comparison with the pressure-induced behavior of previously studied cancrinite-group minerals are carried out.
      Graphical abstract image

      PubDate: 2014-08-15T18:59:15Z
       
  • Preparation and catalytic properties of mesoporous titanosilicate of cubic
           Pm3n structure
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Tsung-Han Lin , Chin-Chang Chen , Ling-Yun Jang , Jyh-Fu Lee , Soofin Cheng
      Mesoporous titanosilicate of cubic Pm3n structure was prepared for the first time using cetyltriethylammonium (CTEA+) bromide as pore-directing agent in alkaline condition (pH around 9) with the aid of NaCl salt. The alkaline synthesis condition facilitated the incorporation of Ti(IV) into the silica framework as well as the assembly of mesoporous silica with zeolite seeds. Two kinds of silica sources were used. The material prepared with sodium silicate was named Ti-SBA-1-alk, and the other named Ti-ZSBA-1 was prepared with the seeds of titanosilicalite-1 (TS-1). The studies by UV–Vis and Ti K-edge XANES spectra indicated that the Ti(IV) in Ti-SBA-1-alk was favorably in tetrahedral (Td) coordination and should be incorporated into the framework of mesoporous silica, whereas a larger amount of Ti(IV) in Ti-ZSBA-1 was in octahedral coordination. In oxidation of 2,3,6-trimethylphenol (TMP) to 2,3,5-trimethylbenzoquinone (TMBQ) using hydrogen peroxide as the oxidant, the mesoporous titanosilicate materials were found to be efficient catalysts, while only trace TMP conversion was observed over TS-1 due to its small zeolitic pores. In comparison of mesoporous titanosilicate materials in similar pore diameters, Ti-SBA-1-alk and Ti-ZSBA-1 both of cubic Pm3n structure gave higher TMBQ selectivities than Ti-MCM-41 of 2D channeling pores, attributing to the better diffusion of the phenoxyl radicals in the three-dimensional pores. Moreover, Ti-SBA-1-alk which contained more Td-coordinated Ti(IV) showed higher catalytic activities than Ti-ZSBA-1.
      Graphical abstract image

      PubDate: 2014-08-11T18:44:31Z
       
  • Propane/propylene separation in ion-exchanged zeolite-like metal organic
           frameworks
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Barış Demir , M. Göktuğ Ahunbay
      Propane/propylene separation performances of zeolite-like metal organic frameworks with rhombic and sodalite topologies (rho- and sod-ZMOFs) were estimated via Monte Carlo simulations over a wide range of pressure in order to evaluate their potential use in pressure swing adsorption applications. Extra-framework cation locations of the “as-synthesized” ZMOFs were identified based on the available experimental data. Selectivities and working capacities before and after the ion exchange of ZMOFs with Li+, Na+, and K+ ions were compared, by considering partially and completely ion-exchanged structures. Results showed that the difference in the dipole moments of propane and propylene is the dominant factor in separation and ion-exchanging enhances the propylene selectivity of ZMOFs. The enhancement is especially significant in sod-ZMOF structures for which a ten-fold increase in the selectivities was obtained, although their working capacities remained lower than those of rho-ZMOF structures.
      Graphical abstract image

      PubDate: 2014-08-11T18:44:31Z
       
  • One-pot synthesis of LiFePO4–carbon mesoporous composites for Li-ion
           batteries
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Shijiao Sun , Camelia Matei Ghimbeu , Raphaël Janot , Jean-Marc Le Meins , Alice Cassel , Carine Davoisne , Christian Masquelier , Cathie Vix-Guterl
      The synthesis of LiFePO4–carbon mesoporous composites by a one-pot soft-template approach is reported along with their performances as positive electrodes for Li-ion batteries. The synthesis is based on the multi-constituent co-assembly of triblock copolymer, resol and (Li, Fe, P) precursors followed by thermal treatment to in-situ generate the carbon matrix with embedded LiFePO4 particles. The effects of the Fe/Li precursor type and the thermal annealing temperature on the phase formation, mesostructural regularity, porosity and Fe oxidation state were systematically investigated by a large panel of analysis techniques. This new synthesis method allowed the successful synthesis of mesoporous LiFePO4–carbon composites with high surface area, defined pore size and small homogenously distributed LiFePO4 particles (20–50nm). These composites can be used as electrodes without extra carbon black additive and demonstrate high rate capability (up to 10C) with a significant capacity contribution from carbon.
      Graphical abstract image

      PubDate: 2014-08-11T18:44:31Z
       
  • Fabrication and characterization of micro/nanoporous Cr film for sensing
           applications
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Mohamed Shaban , Ashour M. Ahmed , Ehab Abdel-Rahman , Hany Hamdy
      A novel technique is developed to fabricate micro/nanoporous Cr film on an Al substrate using DC electrodeposition via the simultaneous etching of the porous anodic alumina (PAA) membrane. The structures and morphologies of the fabricated structures were characterized by field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX), and X-ray diffraction (XRD). Vertically aligned and highly ordered alumina (Al2O3) nanowires of length 4μm, diameter 36nm, and yield of 2×1011 wire/cm2 are observed over etching time of 30min at a current density of 2A/cm2. In addition, nanoconcaves array is formed on the Al substrate at a current density of 4A/cm2. This array was used as a substrate for the growth of micro/nanoporous Cr film after a deposition time of 45min. For the morphological comparison, Cr electrodeposition on the Al substrate was carried out at the same conditions and shown a nonporous film of Cr spheroids. The nanoporous Cr film was used as a substrate for the detection of Hg2+ based on laser induced fluorescence (LIF). Upon the increase of the concentration of Hg2+ ions from 1 to 10μM, additional emission peak is observed and showed a blue-shift of 100nm. In addition, the coordination between the nano-rough surface and Hg2+ ions disrupted the photo-induced electron transfer process leading to the increase of the intensity of fluorescence emission as the concentration of Hg2+ ions increased.
      Graphical abstract image

      PubDate: 2014-08-11T18:44:31Z
       
  • A new architecture of bowl-type mesoporous TiO2 via facile electrospray
           method
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Hyun-Joong Kim , Jae-Deok Jeon , Jae Woo Chung , Seung-Yeop Kwak
      We demonstrate here the fabrication of a novel morphology of bowl-shaped TiO2 aggregates via a facile electrospray technique using TiO2 nanowires. These have been prepared by using lauric acid via solvothermal synthetic route. The modulation of surface energies of the different crystallographic faces through the use of lauric acid is the key parameter for the anisotropic growth. These aggregates have high specific surface area of up to 93.10m2/g, and relatively large pores with a mean size of 4.68nm. These porous structures can provide a high number of active adsorption sites and act as photo-related reaction centers. The prepared bowl-shaped TiO2 are in micrometer size and have good morphology and high specific surface area. A possible mechanism for the formation of bowl-shaped TiO2 aggregates is also proposed, based on the results. The light scattering properties of bowl-shaped architectures are characterized by the UV–Vis spectrometry. The superior light scattering abilities of bowl-shape makes them promising architectures for applications in the photovoltaic devices.


      PubDate: 2014-08-11T18:44:31Z
       
  • pH-dependent loading of Pt nanoparticles protected by dendrimer in calcium
           phosphate matrices
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Yakub Fam , Toyoko Imae , Jonathan Miras , Maria Martinez , Jordi Esquena
      Composites (CaP-DENPtNPs) of calcium phosphate particles (CaPs) with Pt nanoparticles protected by dendrimers (DENPtNPs) were synthesized at different pH following a hydrothermal synthesis method. The CaP matrix in CaP-DENPtNPs composites possessed hydroxyapatite crystalline structures at pH 12 and 8, but monetite crystals were obtained at pH 4. The particle sizes of the composites increased with decreasing pH, and at the same time the amount of PtNPs in the composites also increased. Furthermore, it was confirmed that CaP-DENPtNPs were mesoporous nanocomposites, and DENPtNPs nanoparticles were incorporated mainly on the surface of CaP particles at high pH, but most of DENPtNPs were encapsulated inside CaPs at low pH. The uptake of well-dispersed Pt nanoparticles up to 60wt% in CaPs suggests the possibility of these materials as effective catalysts.
      Graphical abstract image

      PubDate: 2014-08-11T18:44:31Z
       
  • Adsorption study using optimised 3D organised mesoporous silica coated
           with Fe and Al oxides for specific As(III) and As(V) removal from
           contaminated synthetic groundwater
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Yoann Glocheux , Ahmad B. Albadarin , José Galán , Eghe Oyedoh , Chirangano Mangwandi , Claire Gérente , Stephen J. Allen , Gavin M. Walker
      This work presents the possibility of optimising 3D organised mesoporous silica (OMS) coated with both iron and aluminium oxides for the optimal removal of As(III) and As(V) from synthetic contaminated water. The materials developed were fully characterised and were tested for removing arsenic in batch experiments. The effect of total Al to Fe oxides coating on the selective removal of As(III) and As(V) was studied. It was shown that 8% metal coating was the optimal configuration for the coated OMS materials in removing arsenic. The effect of arsenic initial concentration and pH, kinetics and diffusion mechanisms was studied, modelled and discussed. It was shown that the advantage of an organised material over an un-structured sorbent was very limited in terms of kinetic and diffusion under the experimental conditions. It was shown that physisorption was the main adsorption process involved in As removal by the coated OMS. Maximum adsorption capacity of 55mg As(V)g−1 was noticed at pH 5 for material coated with 8% Al oxides while 35mg As(V)g−1 was removed at pH 4 for equivalent material coated with Fe oxides.
      Graphical abstract image

      PubDate: 2014-08-11T18:44:31Z
       
  • Ionothermal syntheses and characterizations of cobalt-substituted
           extra-large pore aluminophosphate molecular sieves with -CLO topology
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Dawei Li , Yunpeng Xu , Yasong Wang , Hao Liu , Bingchun Wang , Huaijun Ma , Renshun Xu , Zhijian Tian
      Cobalt-substituted aluminophosphate molecular sieves with -CLO structure (denoted as CoDNL-1) have been synthesized in the ionic liquid 1-ethyl-3-methylimidazolium bromide with 1,6-hexanediamine as the cooperative structure-directing agent (co-SDA). The influence of various synthesis parameters (e.g. gel compositions and crystallization time) on the synthesis of CoDNL-1 has been investigated in detail. The products have been characterized by powder XRD, SEM, XRF, TG, N2-adsorption, diffuse reflectance UV–Vis spectroscopy, 27Al and 31P MAS NMR spectroscopy and in situ XRD. Powder XRD, TG, chemical analysis and NMR indicate the incorporation of Co2+ ions into the -CLO framework. UV–Vis spectra reveal that Co2+ ions are present in tetrahedral sites of the -CLO framework. In situ XRD analyses show that CoDNL-1 possesses good thermal stability and the cobalt content in the framework influences the thermal stability of CoDNL-1.
      Graphical abstract image

      PubDate: 2014-08-11T18:44:31Z
       
  • Chalcones isothiocyanate anchored into mesoporous silicate: Synthesis,
           characterization and metal ions sensing response
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Tarek A. Fayed , Mohamed H. Shaaban , Marwa N. El-Nahass , Fathy M. Hassan
      Fluorescent nanosensors are one of the most efficient techniques used for detection of toxic metal ions, based on ligand embedded into mesoporous materials. Here, novel ligands of chalcone isothiocyanate analogue namely; phenyl chalcone isothiocyanate (PCITC), naphthyl chalcone isothiocyanate (NCITC) and anthryl chalcone isothiocyanate (ACITC) were synthesized. Also, the 3D mesoporous silicate, KIT-6, was prepared through surfactant-template method. The design of fluorescent nanosensors was achieved by anchoring of CITCs into KIT-6 via the coupling agent (3-aminopropyl) triethoxysilane (APS). The obtained mesoporous silicate and CITCs anchored forms were characterized using different spectroscopic techniques. Among of metal ions, the most widely toxins, Pb(II), Cu(II) and Pd(II) were studied. Sensing of these metal ions was performed using steady-state absorption and emission techniques. A gradual increase in the absorption spectra was observed upon increasing the concentrations of the used metal ions ranging from 5ppb to 1ppm, with instantaneous color change. Also, a great enhancement in the fluorescence intensity was clearly observed, confirming the formation of [M(CITCs-KIT-6) n ]2+ complexes. The calculated binding constants show the high efficiency of PCITC-KIT-6 nanosensor in binding and detection of these metal ions. Moreover, Pb(II) is the strongest binded metal ion with the investigated fluorescent nanosensors. Therefore, CITCs fluorescent nanosensors are suitable for the on-line analysis and remote determination of these toxic metal ions, specially Pb(II), at low concentration levels.
      Graphical abstract image

      PubDate: 2014-08-11T18:44:31Z
       
  • Multi-wall carbon nanotube@zeolite imidazolate framework composite from a
           nanoscale zinc oxide precursor
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Yanfeng Yue , Bingkun Guo , Zhen-An Qiao , Pasquale F. Fulvio , Jihua Chen , Andrew J. Binder , Chengcheng Tian , Sheng Dai
      Nanocomposite of multi-walled carbon nanotube@zeolite imidazolate frameworks (MWNT@ZIF) was prepared through a nanotube-facilitated growth based on a nanosized ZnO precursor. The electrically conductive nanocomposite displays a capacity of 380mAh/g at 0.1°C in Li–sulfur battery, transforming electrically inactive ZIF into the active one for battery applications.
      Graphical abstract image

      PubDate: 2014-08-11T18:44:31Z
       
  • Unique structural characteristics of tin hydroxide nanoparticles-embedded
           montmorillonite (Sn-Mont) demonstrating efficient acid catalysis for
           various organic reactions
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Yoichi Masui , Jiacheng Wang , Kentaro Teramura , Toshihiro Kogure , Tsunehiro Tanaka , Makoto Onaka
      Tin hydroxide nanoparticles-embedded montmorillonite (Sn-Mont) was prepared by the simple treatment of sodium ion-exchanged montmorillonite (Na-Mont) with aqueous SnCl4, the physical and chemical properties of which were investigated by N2 adsorption, XRD, TG, TEM, 119Sn-MAS-NMR, and XAFS analyses. It was revealed that Sn-Mont was composed of Sn(OH)4-based nanoparticles (nano-Sn(OH)4) of less than 3nm in diameter surrounded by delaminated montmorillonite aluminosilicate unit layers. The arrangement of each aluminosilicate unit layer in the Sn-Mont is not laminated like that of the parent Na-Mont, but almost completely disordered to make a porous structure with a high surface area and a large pore volume that embraces the tin hydroxide-based nanoparticles. The intrinsic solid acid catalysis of Sn-Mont was used for the cyanotrimethylsilylation of benzophenone with cyanotrimethylsilane in an excellent yield, which was ascribed to the smooth reactant/product transfers in the micro/meso pores as well as the acidic property of the nano-Sn(OH)4 enwrapped by the delaminated aluminosilicate unit layers.
      Graphical abstract image

      PubDate: 2014-08-11T18:44:31Z
       
  • Membrane processes for the facilitated extraction of disaccharide sugars:
           Parameters and mechanism
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Khalifa Touaj , Oussama Kamal , El Houssaine EL Atmani , Tarik Eljaddi , Laurent Lebrun , Miloudi Hlaïbi
      A supported liquid membrane (SLM) containing a lipophilic agent methyl cholate as carrier, previously used for the facilitated transport of monosaccharides, has been used for the selective extraction of some disaccharides: Lactulose, Lactose, Maltose, Melezitose, Sucrose and Trehalose. The membrane is made of a micro porous poly(vinylidene difluoride) film (PVDF), impregnated with a 0.01M solution of the carrier in xylene. This prepared SLM is remarkably stable for at least 20days. The parameters, permeabilities (P) and initial fluxes (J 0) on the facilitated extraction across the studied SLM, for these sugars, were determined. On the basis of the flux dependence on the initial concentrations of carrier and transported substrate, the rate-determining step in the transport mechanism is shown to be the migration of the sugar–carrier complex (ST) in the membrane organic phase. The initial flux of transported sugar is related to the initial concentration of this substrate in feed phase by a saturation law, which has allowed the determination of the parameters, apparent diffusion coefficient D∗ and the association constant K ass of the formed complex (ST) in the SLM organic phase. The results clearly indicate that these all sugar-carrier complexes are unstable, which results in higher coefficients D∗ and thus a high permeability of this membrane type to facilitated extraction of these disaccharides. While, the stability of these complexes varies widely depending on the molecular structure of each disaccharide, confirming the molecular recognition phenomenon by the carrier and can identify interaction sites (substrate–carrier) involved during the extraction these carbohydrates
      Graphical abstract image

      PubDate: 2014-08-11T18:44:31Z
       
  • Biphenyl-bridged periodic mesoporous organosilicas: Synthesis and in situ
           charge-transfer properties
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Meng Gao , Shuhua Han , Xiaoyong Qiu , Hui Wang
      Using a novel cationic oligomer surfactant as the structure-directing agent, the fluorescent biphenyl-bridged periodic mesoporous organosilicas (BpUPMOs) were successfully synthesized through the cohydrolysis and cocondensation of 4,4′-bis(3-triethoxysilyl propylureido) biphenyl (BpUSi) and tetraethoxysilane (TEOS). The structure characterization of the samples was obtained by FT-IR spectra, small-angle X-ray scattering (SAXS), high resolution transmission electron microscopy (HRTEM), and nitrogen adsorption–desorption analyses. The results showed that ordered mesoporous structure was obtained below 40mol% of the content of BpUSi. With the increase of the amount of BpUSi, the ordering degree of mesoporous structure of BpUPMOs decreased. Fluorescence emission spectra of BpUPMOX (X is a mole fraction of BpUSi, 0%, 10%, 20%, 30%, 40%, 50%, respectively) showed gradually enhanced and red-shifted bands from 357 to 372nm as X was less than 30mol%. However, with further increase of X value, the bands at 359nm for BpUPMO40 and at 354nm for BpUPMO50 exhibited blue-shift compared with that of the sample BpUPMO30 (372nm). This fluorescence phenomenon induced by the amount of organosilicone in the PMOs has not been reported. Furthermore, Charge-transfer (CT) complex composed of BpUPMO20 and decylviologen was obtained, in which the biphenyl groups were as electron donors in the pore walls and the decylviologen molecules were as electron acceptors in the mesochannels of BpUPMO. UV–vis diffuse reflectance spectra and fluorescence spectra showed the existence of CT complex. Besides, the color of CT complex was over a wide range from the salmon pink to red brown.
      Graphical abstract image Highlights A series of biphenyl-bridged periodic mesoporous organosilicas (BpUPMOs) with unique fluorescent properties is successfully synthesized. Charge-transfer (CT) complex composed of biphenyl groups as electron donors in the pore walls and the decylviologen molecules as electron acceptors in the mesochannels of PMO is obtained, which the color of CT complex is over a wide range from the salmon pink to red brown.

      PubDate: 2014-08-11T18:44:31Z
       
  • Editorial Board
    • Abstract: Publication date: October 2014
      Source:Microporous and Mesoporous Materials, Volume 197




      PubDate: 2014-08-06T18:40:15Z
       
  • Influence of tetrahydrofuran (THF) in the synthesis of zeolite ZK-5
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): L.J. Garces , B. Hincapie , X. Shen , V.D. Makwana , D.R. Corbin , A. Sacco , S.L. Suib
      ZK-5 (KFI) molecular sieve was synthesized in the K2O:SrO:Al2O3:SiO2:160 H2O:THF system using conventional hydrothermal heating. Effect of tetrahydrofuran (THF) was investigated. Products were characterized by XRD, TGA, FESEM, EDX and TPD-MS. THF influences the crystallinity and crystal size of ZK-5. The molar ratio of THF/Al2O3 from 0.4 to 1.0 gives the best results in terms of crystallinity (measured by XRD) and purity for the prepared ZK-5. Crystal size of ZK-5 zeolite is reduced by the presence of THF.
      Graphical abstract image Highlights

      PubDate: 2014-08-01T18:10:42Z
       
  • Preparation and studies on properties of porous epoxy composites
           containing microscale hollow epoxy spheres
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Chao-Chen Hsu , Kung-Chin Chang , Tsao-Cheng Huang , Lu-Chen Yeh , Wei-Ting Yeh , Wei-Fu Ji , Jui-Ming Yeh , Tsung-Yen Tsai
      In this work, a series of porous epoxy composites containing microscale, hollow epoxy spheres were synthesized and characterized. First, microscale epoxy spheres were produced using amino-modified silica (AMS) particles with diameters of ∼1μm through a base-catalyzed sol–gel route. The as-synthesized AMS particles were then characterized through Fourier-transform infrared, 13C nuclear magnetic resonance (NMR), and 29Si-NMR spectroscopy. The prepared core–shell particles were immersed into a 1wt.% of HF solution for 24h to remove the inner part of the silica core, leading to the formation of hollow spheres of epoxy with a wall thickness of ∼100nm. These hollow epoxy spheres (HES) were characterized by scanning electron microscopy (SEM), Transmission electron microscopy, and thermogravimetric analysis (TGA). Finally, a series of hybrid materials was synthesized by performing thermal ring-opening polymerization reactions of epoxy resin in the presence of as-synthesized HES. Based on SEM observations on the morphology, the HES showed good dispersion capability in the polymer matrices, which led to a significantly reduced thermal conductivity and slightly decreased dielectric constant based on the transient plane source and LCR measurements, respectively. For example, the thermal conductivity and dielectric constant decreased by 49.3% and 12.6%, respectively, in the porous epoxy material synthesized with a final HES loading of about 10%. One possible reason was the large amount of air present in the material. Other physical characteristics such as the thermal and mechanical properties based on the results of TGA, differential scanning calorimetry, and dynamic mechanical analysis were investigated.
      Graphical abstract image

      PubDate: 2014-08-01T18:10:42Z
       
  • Oxidative dehydrogenation of propane with nitrous oxide over
           Fe–O–Al species occluded in ZSM-5: Reaction and deactivation
           mechanisms
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Guangjun Wu , Yao Hao , Nan Zhang , Naijia Guan , Landong Li , Wolfgang Grünert
      Fe-ZSM-5 was prepared via solid-state exchange method using ferrocene as iron precursor and applied as a model catalyst to investigate the reaction and deactivation mechanisms of the oxidative dehydrogenation of propane (ODHP) with nitrous oxide. Characterization results reveal that after severe calcination highly isolated Fe–O–Al species are the only exposed iron sites detectable, which account for ca. 60% of the total iron species in Fe-ZSM-5. Results from temperature-programmed experiments and in situ DRIFT spectroscopy suggest that the chemisorption of nitrous oxide on Fe–O–Al species leads to the formation of stable mono-oxygen species, which can react with gaseous propane to produce propylene with high selectivity. The accumulation of organic species in the catalyst is observed during the reaction, and the major organic species are determined to be alkylbenzenes. The accumulation rate and the specific constitution of alkylbenzenes are found to depend on the relative partial pressures of propane and nitrous oxide: lower N2O/C3H8 ratios result in formation of aromatics with smaller kinetic diameter, which are accumulated at a lower rate. This leads to lower deactivation rates and longer catalyst lifetimes. Remarkably, a superior stable propane conversion rate of ca. 13mmolgcat −1 h−1 and a propylene production rate of ca. 6mmolgcat −1 h−1 can be kept for >40h with a N2O/C3H8 ratio of 1:2.
      Graphical abstract image

      PubDate: 2014-08-01T18:10:42Z
       
  • Pore characteristics of carbide-derived carbons obtained from carbides
           with different carbon volume fractions
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Jiang Xu , Chao Wu , Pengtao Yan , Ruijun Zhang , Xueqing Yue , Shanhai Ge
      Porous carbide-derived carbons (CDCs) are synthesized by chlorination of carbides with different carbon volume fractions in the temperature range from 400 to 1000°C. It is found that the volume fraction of carbon atoms in carbide precursor has much influence on pore structure of the produced CDC. It is prone to form well ordered graphite to chlorinate carbides with high carbon volume fraction (e.g. VC and TiC). Interlayer spacing of the produced graphite is about 0.34nm. Its thickness increases with chlorination temperature, which leads to a monotonous increase of pore size in the produced CDC. As for the CDCs synthesized from carbides with low carbon volume fraction (e.g. NbC), it is mainly composed of single or bi-layer graphene. The pore size distribution of these NbC–CDCs is insensitive to chlorination temperature. NbC–CDC synthesized at moderate temperature (600 or 800°C) contains a large amount of micropores (∼0.8nm) and small amount of mesopores. Since almost all of these micropores are end-opened, the produced NbC–CDC has high specific surface area (>2000m2 g−1).
      Graphical abstract image

      PubDate: 2014-08-01T18:10:42Z
       
  • CO2 selective NaMg-CTS-1 and its structural formation from the titanium
           silicate based molecule sieve NaMg-ETS-4
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Ocean Cheung , Jie Su , Zoltán Bacsik , Jing Li , Louise Samain , Xiaodong Zou , Niklas Hedin
      A range of titanium silicates (ETS-4 and CTS-1) with interesting gas separation properties were studied as CO2 adsorbents. Some of these adsorbents, in particular NaMg-CTS-1, showed the ability to selectively adsorb CO2-over-N2. Partially exchanged NaM-ETS-4 (M=Mg, Ca, Sr and Ba) were synthesised in the Na+ form and ion exchanged with group 2 cations. All but NaBa-ETS-4 transformed into their CTS-1 counterparts, when these partially exchanged Na-ETS-4 were dehydrated. The transformation from ETS-4 to CTS-1 was monitored and studied extensively using diffraction and spectroscopic techniques. Powder X-ray diffraction allowed us to follow the changes of the unit cell parameters occurred at different temperatures. We combined high energy X-ray total scattering (analysed by pair distribution functions – PDF analysis), electron diffraction, infrared, Raman and Nuclear Magnetic Resonance (NMR) spectroscopy to study the transformation of ETS-4 to CTS-1. We understood that under dehydration steps, there was significant disruption to the Ti–O–Ti chain along the b-axis, which occurred concurrently with the distortion of the double 3-rings alongside of these chains. These changes were partly responsible for the contraction of the ETS-4 framework (and successive transformation to CTS-1). The new information allowed us to understand the interesting structures and sorption properties of these adsorbents.
      Graphical abstract image

      PubDate: 2014-08-01T18:10:42Z
       
  • Ion-exchange resin modified with aggregated nanoparticles of zirconium
           hydrophosphate. Morphology and functional properties
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Yuliya S. Dzyazko , Ludmila N. Ponomaryova , Yurii M. Volfkovich , Vladimir V. Trachevskii , Alexey V. Palchik
      Organic–inorganic ion-exchangers based on gel-like strongly acidic resin, which contain different amount of zirconium hydrophosphate, have been obtained. The samples were investigated using methods of transmission and scanning electron microscopy, standard contact porosimetry, NMR 35P spectroscopy. Nanoparticles of the inorganic constituent (10nm) are deposited in voids between geld field and in structure defects of the polymer forming aggregates of micron size. These large particles squeeze and stretch pores of the polymer, where –SO3 groups are located, a radius of these pores decreases from 10nm down to 2nm. A part of functional groups of the polymer component are excluded from ion exchange due to squeezing of pores, ion exchange properties are determined mainly by the inorganic constituent. Ion exchange capacity of the composites reaches 0.6–1.3mmolcm−3. These materials sorb preferably Cd2+ and Ni2+ from solutions, which contain also hardness ions. The highest break-through capacity has been found for the composite with the smallest microporosity of the polymer constituent, this value reaches 80% of total ion-exchange capacity.
      Graphical abstract image

      PubDate: 2014-08-01T18:10:42Z
       
  • Micro-structural information of porous materials by optical coherence
           tomography
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): S.L. Campello , W.P. dos Santos , V.F. Machado , C.C.B.O. Mota , A.S.L. Gomes , R.E. de Souza
      In this study we describe the use of optical coherence tomography (OCT) to reveal microstructures and damages in porous media. An approach for establishing pore size and pore size distribution based upon OCT was developed. This approach was tested with oil source rock samples. Several sedimentary rock samples from Brazilian oil fields with porosity values ranging between 15% and 28% were evaluated, and the results agreed quite well with the traditional pycnometry method. In addition, pore size distribution for the samples in three dimensional planes were obtained. Finally, the experimental results proved that the OCT images with a suited digital post-processing can be used to measure pore size distribution in natural and artificial materials, with the advantage of being non-invasive, faster and much less expensive than other presently available methods.
      Graphical abstract image

      PubDate: 2014-08-01T18:10:42Z
       
  • Preparation and characterization of activated carbon from plant wastes
           with chemical activation
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Metin Açıkyıldız , Ahmet Gürses , Semra Karaca
      Activated carbon has been widely used in the sorption of chemical species from aqueous solutions as a versatile adsorbent with optimal sorption properties. However, production and regeneration of commercial activated carbons are still expensive and so the importance of activated carbon production by using low-cost raw materials and methods are still up to date. In this study, a one-step chemical activation process by zinc chloride was used to obtain activated carbon from plant wastes (PWs) such as pine sawdust (PS), rose seed (RS), and cornel seed (CS). The effect of activation parameters such as carbonization temperature, impregnation (ZnCl2/PW) ratio, and impregnation time on the properties of final products were investigated. The produced activated carbons were characterized by nitrogen adsorption isotherms at 77K. The present results showed that the surface area and methylene blue index of activated carbons, which were determined by adsorption tests, were achieved as high as 1825m2/g and 300mg/g in their highest value, respectively.
      Graphical abstract image

      PubDate: 2014-08-01T18:10:42Z
       
  • Silicate ionic liquid synthesis of zeolite merlinoite: Crystal size
           control from crystalline nanoaggregates to micron-sized single-crystals
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Mohamed Haouas , Louwanda Lakiss , Charlotte Martineau , Jaafar El Fallah , Valentin Valtchev , Francis Taulelle
      A new procedure for zeolite synthesis based on a silicate ionic liquid is reported. The method consists of a two-step precursor preparation. In the first step, a liquid silicate is prepared by hydrolyzing tetraethylorthosilicate (TEOS) with KOH–H2O mixture, which induces coacervation resolved into full phase demixing and subsequent separation from a water–ethanol phase by simple decantation. In the second step, an appropriate amount of an alkaline aluminate is mixed with the first liquid silicate, avoiding therefore precipitation. To the best of our knowledge, this represents the first example of homogeneous liquid synthesis, and not a clear sol or a gel, of an Al-rich zeolite, free of organic template. The approach is exemplified by the synthesis of merlinoite with potassium hydroxide as mineral base and could be extended to other zeolitic systems by varying the chemical composition and the nature of the alkali cation. The synthesis yield depends on the Al content and the crystalline products showed a very large range of particle sizes varying from nanometer scale to about a hundred microns when increasing the Al concentration. Crystallization proceeds most likely through nucleation from a liquid where nucleation and growth directly affects the ultimate crystal size and morphology.
      Graphical abstract image

      PubDate: 2014-08-01T18:10:42Z
       
  • Effect of lanthanum and phosphorus on the aromatization activity of
           Zn/ZSM-5 in FCC gasoline upgrading
    • Abstract: Publication date: 1 November 2014
      Source:Microporous and Mesoporous Materials, Volume 198
      Author(s): Huayun Long , Fengying Jin , Guang Xiong , Xiangsheng Wang
      The effects of La and P addition on the physicochemical properties and the aromatization performance of Zn/ZSM-5 were investigated. The introduction of Zn decreased the amount of Brönsted acid sites and increased that of Lewis acid sites of nanoscale ZSM-5. To improve the yields of aromatics in the aromatization of olefins on bifunctional catalysts, it is necessary to increase the participation of the dehydrogenation reactions in the formation of dienes and the corresponding aromatics from cyclic intermediates in n-octene aromatization. XPS results indicated that the addition of La to Zn/ZSM-5 improves the dispersion of zinc species, strengthens the zinc species-support interaction, increases the amount of [Zn(OH)]+ species, and thus improves the aromatization activity. P addition resulted in the presence of zinc species located in the channels of nanoscale HZSM-5 and enhanced the stability of the catalyst. The synergistic effect of La and P increased the amount of [Zn(OH)]+ species, decreased the loss of zinc species and consequently increased the aromatization activity and the stability of the catalyst. The FCC gasoline upgrading results showed that olefins can be converted into aromatics over ZnLaP/ZSM-5 to compensate the loss of octane number, which suggests a good prospect for application in industry.
      Graphical abstract image

      PubDate: 2014-08-01T18:10:42Z
       
  • 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
       
  • 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
       
  • 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
       
 
 
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