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  Subjects -> PHYSICS (Total: 793 journals)
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PHYSICS (572 journals)            First | 1 2 3 4 5 6 | Last

Journal of Physical Chemistry C     Full-text available via subscription   (Followers: 28)
Journal of Physical Oceanography     Full-text available via subscription   (Followers: 8)
Journal of Physical Organic Chemistry     Hybrid Journal   (Followers: 9)
Journal of Physics A : Mathematical and Theoretical     Hybrid Journal   (Followers: 4)
Journal of Physics and Chemistry of Solids     Hybrid Journal   (Followers: 4)
Journal of Physics D : Applied Physics     Hybrid Journal   (Followers: 9)
Journal of Physics: Condensed Matter     Hybrid Journal   (Followers: 8)
Journal of Physics: Conference Series     Open Access   (Followers: 2)
Journal of Plasma Physics     Hybrid Journal   (Followers: 4)
Journal of Polymer Science Part B: Polymer Physics     Hybrid Journal   (Followers: 24)
Journal of Porous Materials     Hybrid Journal   (Followers: 3)
Journal of Porphyrins and Phthalocyanines     Hybrid Journal   (Followers: 2)
Journal of Quantitative Spectroscopy and Radiative Transfer     Hybrid Journal  
Journal of Reinforced Plastics and Composites     Hybrid Journal   (Followers: 28)
Journal of Research in Physics     Open Access  
Journal of Rheology     Full-text available via subscription   (Followers: 5)
Journal of Romance Studies     Full-text available via subscription   (Followers: 2)
Journal of Sandwich Structures and Materials     Hybrid Journal   (Followers: 1)
Journal of Scientific Research     Open Access   (Followers: 2)
Journal of Semiconductors     Full-text available via subscription   (Followers: 2)
Journal of Sensors     Open Access   (Followers: 9)
Journal of Sol-Gel Science and Technology     Hybrid Journal   (Followers: 1)
Journal of Solid State Lighting     Open Access  
Journal of Solid State Physics     Open Access   (Followers: 1)
Journal of Spectroscopy     Open Access   (Followers: 7)
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: 19)
Journal of the American Society for Mass Spectrometry     Hybrid Journal   (Followers: 21)
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: 5)
Journal of Ultrasound in Medicine     Full-text available via subscription   (Followers: 5)
Journal of Vibration and Control     Hybrid Journal   (Followers: 30)
Journal of Visualization     Hybrid Journal   (Followers: 2)
Journal of Zhejiang University SCIENCE A     Hybrid Journal  
Jurnal Fisika     Open Access  
Jurnal NEUTRINO     Open Access  
Jurnal Pendidikan Fisika Indonesia (Indonesian Journal of Physics Education)     Open Access   (Followers: 1)
Jurnal Penelitian Fisika dan Aplikasinya     Open Access   (Followers: 1)
Jurnal Penelitian Sains (JPS)     Open Access  
Karbala International Journal of Modern Science     Open Access  
Language Learning Journal     Hybrid Journal   (Followers: 17)
Lasers in Surgery and Medicine     Hybrid Journal   (Followers: 1)
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: 2)
Light : Science & Applications     Open Access  
Living Reviews in Relativity     Open Access  
Living Reviews in Solar Physics     Open Access   (Followers: 1)
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: 5)
MAPAN     Hybrid Journal  
Mass Spectrometry Reviews     Hybrid Journal   (Followers: 21)
Matéria (Rio de Janeiro)     Open Access   (Followers: 1)
Materials & Design     Hybrid Journal   (Followers: 36)
Materials at High Temperatures     Full-text available via subscription   (Followers: 4)
Materials Chemistry and Physics     Full-text available via subscription   (Followers: 15)
Materials Research     Open Access   (Followers: 7)
Materials Research Bulletin     Hybrid Journal   (Followers: 22)
Materials Research Innovations     Hybrid Journal   (Followers: 1)
Materials Science     Hybrid Journal   (Followers: 8)
Materials Science and Engineering: A     Hybrid Journal   (Followers: 41)
Materials Science and Engineering: B     Hybrid Journal   (Followers: 20)
Materials Science and Engineering: C     Hybrid Journal   (Followers: 20)
Materials Science and Engineering: R: Reports     Hybrid Journal   (Followers: 14)
Materials Science and Technology     Hybrid Journal   (Followers: 41)
Matériaux & Techniques     Full-text available via subscription   (Followers: 2)
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: 18)
Mechanics of Time-Dependent Materials     Hybrid Journal   (Followers: 1)
Mechanics Research Communications     Hybrid Journal   (Followers: 2)
Metamaterials     Hybrid Journal   (Followers: 2)
Micro and Nano Systems Letters     Open Access   (Followers: 4)
Microfluidics and Nanofluidics     Hybrid Journal   (Followers: 10)
Microporous and Mesoporous Materials     Hybrid Journal   (Followers: 6)
Modern Instrumentation     Open Access   (Followers: 15)
Modern Physics Letters A     Hybrid Journal   (Followers: 1)
Modern Physics Letters B     Hybrid Journal   (Followers: 1)
Molecular Diversity     Hybrid Journal  
Moscow University Physics Bulletin     Hybrid Journal  
Multibody System Dynamics     Hybrid Journal   (Followers: 1)
NANO     Hybrid Journal   (Followers: 7)
Nano Letters     Full-text available via subscription   (Followers: 56)
Nano Reviews     Open Access   (Followers: 14)
Nano-Micro Letters     Open Access   (Followers: 1)
NanoBioImaging     Open Access  
Nanomechanics     Open Access  
Nanoscale and Microscale Thermophysical Engineering     Hybrid Journal   (Followers: 3)
Nanoscale Research Letters     Open Access   (Followers: 3)
Nanospectroscopy     Open Access  

  First | 1 2 3 4 5 6 | Last

Journal Cover Microporous and Mesoporous Materials
  [SJR: 1.306]   [H-I: 102]   [6 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1387-1811
   Published by Elsevier Homepage  [2801 journals]
  • Modified seeding method for preparing hierarchical nanocrystalline ZSM-5
           catalysts for methanol aromatisation
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): Yan Gao, Guang Wu, Fangwei Ma, Chuntao Liu, Fan Jiang, Yu Wang, Anjie Wang
      A series of ZSM-5 nanozeolites with hierarchical porosity were prepared by a seeding method and the addition of phenylaminopropyltrimethoxysilane (PATMOS) into the medial synthesis system. The influence of the amounts of PATMOS on the pore characteristics, crystallinity, morphology and acidity of the ZSM-5 zeolites were studied by XRD, N2-adsorption, 27Al MAS NMR, SEM, TEM and NH3-TPD. The crystal size of the ZSM-5 zeolites could be adjusted in a certain range, and the mesopores were generated by introducing PATMOS. In addition, the catalytic performances of the hierarchical nanocrystalline ZSM-5 were investigated for methanol aromatisation (MTA). The hierarchical nanocrystalline ZSM-5 catalysts with a small crystal size and numerous mesopores exhibited high stability for the MTA reaction due to an enhanced mass transfer property and reduced diffusion limitations.
      Graphical abstract image

      PubDate: 2016-01-30T13:25:52Z
       
  • Controlled delivery of drugs adsorbed onto porous Fe3O4 structures by
           application of AC/DC magnetic fields
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): Mislav Mustapić, Md Shahriar Al Hossain, Joseph Horvat, Pawel Wagner, David R.G. Mitchell, Jung Ho Kim, Gursel Alici, Yoshitaka Nakayama, Boris Martinac
      Porous structures made up of Fe3O4 nanoparticles were used to adsorb methyl blue in water. Controlled release of the methyl blue to water was then achieved by application of a magnetic field. Application of a pure DC field did not result in any release. Application of a pure AC field caused released of the methyl blue. However, a combination of both DC and AC fields resulted in much faster release. The mechanism by which this operated is believed to result from viscous friction. Nanoparticles are strongly aligned in the DC field and oscillate under the influence of the AC field. This study demonstrates a concept for controlled drug delivery, where pharmaceutical molecules, similar to methyl blue, would be adsorbed onto porous Fe3O4 structure and the released at a target by application of appropriately localised magnetic fields.
      Graphical abstract image

      PubDate: 2016-01-24T09:28:01Z
       
  • A comparative study on adsorption and photocatalytic dye degradation under
           visible light irradiation by mesoporous MnO2 modified MCM-41 nanocomposite
           
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): Binita Nanda, Amaresh C. Pradhan, K.M. Parida
      In situ incorporation of semiconducting mesoporous MnO2 (meso-MnO2) into the MCM-41 generates a high surface area meso-MnO2–MCM-41 nanocomposite. The structural, morphological, optical and electronic properties of these catalysts were characterized by low angle and broad angle X-ray diffraction (LXRD and BXRD), X-ray photoelectron spectroscopy (XPS), UV–vis DRS spectroscopy and high resolution transmission electron microscopy (HRTEM). The incorporation of meso-MnO2 into MCM-41 through the silanol group forming nanocomposite has been evidenced from FTIR study and 29Si CP–MAS NMR spectra. Among all the catalysts, meso-MnO2–MCM-41(10) showed the highest surface area (1313 m2 g−1), narrow pore diameter (2.04 nm) and high pore volume (0.86 cm3 g−1). The activity of meso-MnO2–MCM-41 samples were compared towards adsorption and degradation of various cationic dyes such as Rhodamine 6G (Rd 6G), Methylene blue (MB), Malachite green (MG) and Rhodamine B (Rd B). The meso-MnO2–MCM-41(10) composite exhibited 100% photo degradation and adsorption activity towards 100 ppm dye solution in 60 min and 90 min, respectively. The high surface area, narrow pore diameter, high pore volume, intra-particle mesoporosity are responsible for high adsorption. Furthermore, the electron transfer and generation of OH radicals are responsible for the enhancement of photo degradation process.
      Graphical abstract image

      PubDate: 2016-01-24T09:28:01Z
       
  • Combined influence of pore size distribution and surface hydrophilicity on
           the water adsorption characteristics of micro- and mesoporous silica
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): Sarmenio Saliba, Patrick Ruch, Willi Volksen, Teddie P. Magbitang, Geraud Dubois, Bruno Michel
      Adsorption processes are ubiquitous in nature as well as of great technological importance for gas separation, purification, storage and thermally driven heat pumps. This has led to a strong interest in the fundamental mechanisms governing adsorption phenomena and their exploitation to tailor adsorption systems for specific applications. In particular, the adsorption of water on porous silica exhibits remarkable properties due to the strong polarity of the adsorbate and moderate hydrophilicity of the adsorbent. It is generally accepted that the adsorption of water vapor on porous silica depends upon the concentration of surface silanols and the pore size. In fact, materials with ordered mesopores and a well-defined pore size have been used as model systems to demonstrate that water adsorption occurs predominantly through capillary condensation. While the pore surface chemistry is modified to become more hydrophilic after filling of the pores in these materials, the overall shape of the water adsorption isotherm (Type V) is not significantly affected in subsequent adsorption measurements. The present contribution shows that conservation of the isotherm shape is a unique phenomenon related to ordered mesopores but doesn't apply to materials with a more complex pore structure. For materials with wider pore size distributions including micropores, a synergistic effect of surface hydroxylation and pore size leads to a dramatic change in the water adsorption isotherm after the first adsorption/desorption cycle. In fact, we demonstrate that the water cycling capacity at relative pressures below the onset of capillary condensation increases significantly in these systems. These results contribute to a fundamental understanding of water adsorption in complex systems and have important implications in applications such as adsorption heat pumps where a large water cycling capacity in a specific relative pressure window is required.
      Graphical abstract image

      PubDate: 2016-01-24T09:28:01Z
       
  • Luminescence properties of lanthanide-containing layered double hydroxides
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): P. Vicente, M.E. Pérez-Bernal, R.J. Ruano-Casero, Duarte Ananias, F.A. Almeida Paz, J. Rocha, V. Rives
      A series of layered double hydroxides with the hydrotalcite structure containing Mg2+ and Al3+ cations in the brucite-like layers and carbonate in the interlayer have been prepared, with different lanthanide cations (4% loading) in the brucite-like layers. The solids have been characterized by element chemical analysis, powder X-ray diffraction, thermal analysis, particle size distribution, FT-IR and UV–Vis spectroscopies and surface texture by adsorption–desorption of nitrogen at – 196 °C. The color and luminescent properties have been also studied. The results confirmed the hydrotalcite-type structure, without any sort of contaminating phases. The solids have been calcined at 1000 °C forming homogeneously dispersed mixed oxides, where the rock-salt structure of MgO and the MgAl2O4 spinel have been identified by powder X-ray diffraction, without any differentiated phase containing lanthanide ions. The samples (original and calcined) containing Tb3+ exhibited green fluorescence, detected under irradiation of 254 and 365 nm. The emission spectra showed a series of narrow lines ascribed to the Tb3+ 5D4→7F6−2 transitions. The decay curves monitored at 543 nm indicated the presence of a single local Tb3+ environment in the parent and calcined samples. For the calcined samples, the photoluminescence evidence supports the insertion of Tb3+ in MgAl2O4 rather than in MgO.
      Graphical abstract image

      PubDate: 2016-01-24T09:28:01Z
       
  • Hierarchical zinc oxide pomegranate and hollow sphere structures as
           efficient photoanodes for dye-sensitized solar cells
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): Ratna Chauhan, Manish Shinde, Abhinav Kumar, Suresh Gosavi, Dinesh P. Amalnerkar
      The hierarchically structured ZnO pomegranates as well as hollow spheres have been prepared in a solvothermal assisted process using ethylene glycol as a solvent and l-ascorbic acid and oxalic acid as additives/surfactants respectively, without using water as solvent. Depending on the surfactant used, the morphology of the ZnO hierarchical nanostructures has changed dramatically which can be attributed to the reaction kinetics affected by presence of generated solvents, evolved gases. The structural analysis reveals the formation of wurtzite hexagonal crystalline structure. Electron microscopy images show the pomegranate and hollow sphere like morphology. The secondary nanoscale growth has been observed on the shell of pomegranate like ZnO microspheres. The synthesized ZnO hierarchial nanostructures have been used as photoanode in dye sensitized solar cells (DSSCs) which showed enhanced light harvesting properties than the commercial ZnO. Pomegranate like structure has displayed better light conversion efficiency (4.35%) as compared to ZnO hollow sphere structures (3.28%). This enhancement in photocurrent and power conversion efficiency could be due to interesting pomegranate like architecture of ZnO coupled with secondary 1-dimensional growth which provided more specific surface area for dye loading.
      Graphical abstract image

      PubDate: 2016-01-24T09:28:01Z
       
  • A lattice dynamics study of ZK-4 microporous material under different
           temperature and pressure conditions
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): Jorge Gulín-González, Carlos Torres Pupo, Edisel Navas Conyedo, Andrés Ruiz-Puentes, Pierfranco Demontis, Giuseppe B. Suffritti
      The stability of zeolites is essential for their wide range of applications. Many experimental and theoretical studies have been focused on the stability of zeolites upon both high temperature and pressure conditions. The main objective of the present research was to compare the behavior of zeolite ZK-4 (with a LTA framework type) under a wide range of temperature and pressure conditions. Lattice Dynamics calculations were performed using the software package GULP. We have obtained the unit cell parameters, angles, bond distances and characteristic vibrational properties of zeolite ZK-4 in the range of 0 ≤ P ≤ 6 GPa and 0 ≤ T ≤ 1200 K. The unit cell volume decreased with a temperature increased as an evidence of a Negative Thermal Expansion process. The computational results suggested the strong structural disorder due to the application of the external pressure. Major distortions were present in T–O–T angles, followed by O–T–O angles and T–O distances. In general, comparative analysis based on our results shows that the effect of external pressure is more striking than that of temperature. Elastic constants and bulk moduli for heated and pressurized structures were obtained.
      Graphical abstract image

      PubDate: 2016-01-24T09:28:01Z
       
  • Sulphonic acid functionalized periodic mesoporous organosilica with the
           bridged bissilylated urea groups for high selective adsorption of cobalt
           ion from artificial seawater
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): Sang Hyun Lee, Sung Soo Park, Surendran Parambadath, Chang-Sik Ha
      Bissilylated urea-bridged periodic mesoporous organosilicas (DUP-PMOs) were synthesized by the co-condensation of N,N′-diureylenepyridine-bis-[(3-propyl)triethoxysilane)] (DUP) and tetraethyl orthosilicate (TEOS) using a triblock copolymer (Pluronic P123) as a structure-directing agent at various DUP to TEOS ratios. Sulphonic acid-functionalized PMOs (SUP-PMOs) were prepared based on a reaction between amine groups of DUP-PMO with chlorosulphonic acid in chloroform under mild reaction conditions. These PMOs were well characterized by small angle X-ray scattering, N2 adsorption–desorption measurements, Fourier-transform infrared spectroscopy, solid state 29Si magic angle spinning (MAS) and 13C cross polarisation-MAS nuclear magnetic resonance spectroscopy, transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The DUP-PMOs and SUP-PMOs had an ordered mesostructure, high to low surface area (ranging from 637 to 38 m2 g− 1), medium pore volume (0.69–0.05 cm3 g− 1) and uniform pore sizes (4.3–5.2 nm). The functionalized PMOs were used effectively for the adsorption of Co2+ ions with high selectivity from artificial seawater. Owing to the presence of highly hydrophilic sulphonic acid moieties as pendent functional groups in the 1 and 3 positions of the urea nitrogen atoms, the materials were found to be highly suitable for the adsorption of Co2+ ions from artificial seawater at pH 8 with 96.1% selectivity, even in the presence of several interfering metal ions, such as Cr3+, Cu2+, Ni2+, and Li+. The adsorption experiments showed that the selectivity towards Co2+ depended heavily on the sulphonic acid loading on the surface nitrogen of diureylenepyridine-bridged PMO and the time of contact with metal ions in the artificial seawater.
      Graphical abstract image

      PubDate: 2016-01-20T09:23:22Z
       
  • Controllable synthesis of niobium doped mesoporous silica materials with
           various morphologies and its activity for oxidative catalysis
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): Sumbul Rahman, Sneha Shah, Chianjit Santra, Debasis Sen, Sadanand Sharma, J.K. Pandey, S. Mazumder, Biswajit Chowdhury
      Nb doped HMS-X (Nb-HMS-X) was synthesized by sol–gel/emulsion method using non-ionic tri-block copolymer surfactant PEO140PPO39PEO140 (P123) as a structure directing agent. The effect of synthesis condition on the pore morphology and nature of pore ordering was investigated. Small-angle X-ray Scattering (SAXS) revealed highly ordered pore structure in Nb-HMS-X. It is demonstrated by Field Emission Scanning Electron Microscopy (FESEM) that the materials possessed various morphologies such as, regular spheres, disordered and tube-spheres depending on synthesis conditions. The solid state 29Si nuclear magnetic resonance measurements showed that chemical environment of silicon atoms get modified significantly with synthesis condition. Furthermore, the synthesized niobium doped hollow mesoporous silica (Nb-HMS-X) was effective to catalyze ethyl benzene oxidation reaction where activation of C–H bond took place.
      Graphical abstract image

      PubDate: 2016-01-20T09:23:22Z
       
  • A potential substitute for CeY zeolite used in fluid catalytic cracking
           process
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): Xinmei Liu, Shun Liu, Yuxiang Liu
      The aim of this paper is to decrease the cerium ions in the fluid catalytic cracking (FCC) catalysts. Cu2+, Zn2+, Co2+, Zr4+, and Y3+ cationic ions were respectively investigated to be the Ce3+ substitute ions in Y zeolite. The results indicate that Y3+ is an optimum ion compared to other ions. YY zeolite (prepared with Y3+) possesses more Brönsted acid sites and higher hydrothermal stability than that modified with Cu2+, Zn2+, Co2+, Zr4+ ions. The YY has similar acid sites and acidic distribution to the CeY. The higher framework Si/Al ratio and the stronger polarizing effect of the Y(OH)2+ contribute higher hydrothermal stability to the YY zeolite. Catalysts prepared with CuY, ZnY or CoY performed poorly performance for the heavy oil catalytic cracking. However, the catalyst prepared with YY exhibits a much higher conversion and light oil yield than that prepared with CeY. It demonstrates that YY zeolite is a preferable active component for FCC catalyst.
      Graphical abstract image

      PubDate: 2016-01-16T18:29:08Z
       
  • Hierarchical zeolites as adsorbents for mesosulfuron-methyl removal in
           aqueous phase
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): Sabrina Rasamimanana, Samuel Mignard, Isabelle Batonneau-Gener
      Bulky organic pollutants such as pesticides and pharmaceutical residues are found in wastewater and are difficult to remove by microporous adsorbents because of their large size. Hierarchical zeolites as potential adsorbents for removal of heavy organic pollutants from aqueous phase are investigated. Hierarchical HMOR and HZSM-5 samples were obtained by post-synthesis desilication by alkaline treatment followed or not by acid leaching of the microporous parent zeolites. The obtained materials have been fully characterized by X-ray diffraction, N2 physisorption, elemental analysis, pyridine adsorption followed by FTIR. Alkaline treatments lead to a framework desilication creating mesopores with the preservation of the Brønsted acidity. Material adsorption behaviors are studied in pesticide, mesosulfuron-methyl (MM), removal from aqueous phase. For all the materials, adsorption kinetics are well described by a pseudo-second order model indicating that MM molecules are chemisorbed via acido-basic interaction of the neutral form. Sorption isotherms are S-shape isotherms for the parent samples and evolve to more favorable concave isotherms for highly mesoporous samples. Thus hierarchical zeolites exhibit higher sorption rate and capacities than microporous ones. Soft acid leaching treatments carried out after alkaline one help to clean the zeolite porosity from silica debris and to enhance significantly zeolite adsorption efficiency.
      Graphical abstract image

      PubDate: 2016-01-16T18:29:08Z
       
  • Fe3O4@mZnO nanoparticles as magnetic and microwave responsive drug
           carriers
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): Hongxia Peng, Chuanyue Hu, Jilin Hu, Xiuying Tian, Tengyan Wu
      Mesoporous and core–shell structure nanomaterials have attracted great attention owing to their unique characteristics and promising applications in drug delivery, and water treatment. In this paper, Fe3O4@mZnO (m was short for mesoporous) core–shell structured nanoparticles with magnetic, microwave to heat responsive properties and high specific surface area (93 m2 g−1) were synthesized by a simple template-free homogeneous precipitation method. The nanoparticles not only has the large accessible pore size (6.7 nm) for the physical adsorption of drug molecules and showed both strong magnetic and unique microwave to heat responsive properties, which may lead to development of nanoparticles with great potential for applications in drug targeting, chemo- and microwave-thermal combination therapy and water treatment.
      Graphical abstract image

      PubDate: 2016-01-16T18:29:08Z
       
  • Adsorption interaction in H2-ZSM-5 system and calculation of the zeolite
           microchannel parameters
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): Ivan V. Grenev, Vladimir Yu. Gavrilov
      The adsorption interaction of molecular hydrogen with atoms of silicalite-1 and HZSM-5 zeolite frameworks was studied using a representative fragment of the structure including 27 elementary cells with total volume 144 nm3. Potentials of the adsorption interaction between the sorbate molecules and the lattice atoms (O, Si, Al) were calculated. Isopotential surfaces of the intermolecular interaction were also calculated. The isopotential surface with zero adsorption potential Ф 0 determines the microchannel shape and topology. Theoretical volumes of the zeolite microchannels and geometrical surface areas Ф 0 were calculated. Places where the sorbate molecules are preferentially localized in the zeolite structure (places with the lowest adsorption potential) in the Henry adsorption isotherm region were determined. The calculated and experimental values of the Henry constant for H2 adsorption at 77 K were compared.
      Graphical abstract image

      PubDate: 2016-01-16T18:29:08Z
       
  • Activated carbons with high nitrogen content by a combination of
           hydrothermal carbonization with activation
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): C. Laginhas, J.M. Valente Nabais, M.M. Titirici
      This paper reports the production of carbons materials with a nitrogen content around 8%(w/w) and a well-developed porous structure, with BET surface area and pore volume up to 2130 m2 g−1 and 1.12 cm3 g− 1, respectively, produced by a combination of hydrothermal carbonization, an environmental friendly method in the production of sustainable tunable carbon materials, with traditional activation methods. The porosity was developed through an activation process according to different routes, namely activation with CO2 and chemical activation using CaCO3 and K2CO3. The successful production of activated carbons using chitosan as a nitrogen source revealed to be a good alternative to post-synthesis methods.
      Graphical abstract image

      PubDate: 2016-01-16T18:29:08Z
       
  • MCM-41 silica particles grafted with polyacrylonitrile: Modification in to
           amidoxime and carboxyl groups for enhanced uranium removal from aqueous
           medium
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): Gulay Bayramoglu, M. Yakup Arica
      The uranium ion adsorption on the pristine MCM-41, amidoxime (AMD) and carboxyl (CA) groups modified particles was studied. The amounts of adsorbed U(VI) ions onto the pristine MCM-41, CA and AMD modified MCM-41 particles were found to be 58.9, 296.7 and 442.3 mg/g, respectively. The experimental equilibrium data was found to fit the Langmuir model well for all the tested adsorbents. The pristine, CA and AMD modified particles can be regenerated using 10 mM HNO3 solution with more than 95% recovery. Hence, AMD and CA modified particles are stable, and easily regenerated. Particularly, AMD modified MCM-41 particles with high adsorption capacity seems to be a promising adsorbent for removal of U(VI) ions from aqueous solutions.
      Graphical abstract image

      PubDate: 2016-01-16T18:29:08Z
       
  • A continuous flow reactor setup as a tool for rapid synthesis of micron
           sized NaA zeolite
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): Tobias Vandermeersch, Tom R.C. Van Assche, Joeri F.M. Denayer, Wim De Malsche
      Slow crystallization kinetics and a limited thermodynamical stability of the target crystal phase are characteristic to zeolite formation, representing some of the key obstructions for fast zeolite synthesis. In this paper, the possibility of accelerating NaA zeolite synthesis in a continuous flow reactor (CFR) is studied. The CFR reduces the thermal lag by increasing surface to volume ratio, expediting heat transfer and mass transfer. The properties of the CFR and the reference batch synthesized particles were similar as confirmed by X-ray diffraction, scanning electron microscopy, particle size measurement using laser scattering and water adsorption equilibria. The reduced residence time and reduction in thermal lag provided an ideal synthesis environment for NaA zeolite, without side products, yielding 160 g/h per liter reactor volume of dry NaA crystals synthesized in 16 min and 2–3 μm particles for a single CFR. In comparison, the batch process produces 33 g/h per liter reactor volume The effects of diluting with NaOH-solution and temperature were studied in the CFR, allowing to determine the optimal conditions. With the enhanced reaction kinetics gained from the increased temperature and molar composition, NaA synthesis is performed 10 times faster than in the optimal batch synthesis. The optimal conditions for the synthesis of NaA in the CFR were determined as: a gel composition of Na 2 O:4.75 – SiO 2:1.93 – Al 2 O 3:1.0 – H 2 O:192, at a synthesis temperature of 150 °C during 16 min without, aging of the gel mixture. This paper shows that the bottlenecks in NaA zeolite synthesis can be widened resulting in faster synthesis in a CFR, making it a feasible pathway for more controllable zeolite synthesis at higher mass production rates (160 g/(h l-reactor)) while reducing the risk of blockage in a continuous flow reactor.
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      PubDate: 2016-01-16T18:29:08Z
       
  • Metal-organic framework (MIL-101) stabilized ruthenium nanoparticles:
           Highly efficient catalytic material in the phenol hydrogenation
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): Ilknur Efecan Ertas, Mehmet Gulcan, Ahmet Bulut, Mehmet Yurderi, Mehmet Zahmakiran
      Ruthenium(0) nanoparticles stabilized by MIL-101 metal-organic framework (Ru/MIL-101) were prepared via gas phase infiltration of Ru(cod) (cot) (cod = 1,5-cyclooctadiene, cot = 1,3,5-cyclooctatriene) followed by hydrogenolysis of Ru(cod) (cot)@MIL-101 at 3 bar H2 and 323 K. The resulting material was characterized by using various analytical tools including ICP-OES, EA, P-XRD, XPS, DR-UV-VIS, SEM, BFTEM, HRTEM, STEM-EDX, CO-chemisorption and N2-adsorption–desorption technique, which revealed that the formation of ruthenium(0) nanoparticles (4.2 ± 1.2 nm) mainly exist on the surface of MIL-101 by keeping the host framework intact. The application of Ru/MIL-101 in catalysis by considering their activity, selectivity and reusability was demonstrated in the phenol hydrogenation under mild conditions. Ru/MIL-101 acted as active (lower-limit TOF = 29 mol cyclohexanone/mol Ru × h; corrected TOF = 88 mol cyclohexanone/mol Ru × h at ≥ 90% conversion) and selective (≥90%) catalyst in the hydrogenation of phenol to cyclohexanone in water at 323 K and 5 bar initial H2 pressure. More importantly, the resulting ruthenium(0) nanoparticles in Ru/MIL-101 were found to be highly durable throughout the catalytic reuse in the phenol hydrogenation (retain ≥85% of their inherent activity and selectivity at 5th reuse), which makes Ru/MIL-101 a reusable catalytic material for the liquid phase mediated catalytic transformations.
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      PubDate: 2016-01-16T18:29:08Z
       
  • Characterization and stability of a bioactivated alumina nanomembrane for
           application in flow devices
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): M.I. Vázquez, V. Romero, J. Benavente, R. Romero, J. Hierrezuelo, J.M. López-Romero, R. Contreras-Cáceres
      Surface modification of alumina nanomembrane (ANP) by theophylline derivative Theo1 by dip-coating was successfully achieved. The hybrid material was characterized by SEM, XPS and confocal microscopy. The presence of Theo1 on the ANP surface was established from salt diffusion and membrane potentials measurements. Changes in the electrical character and transport parameters of the modified sample, associated to Theo1 deposition, were established. Stability of the material under diffusive flow was also ascertained. Moreover, as a result of Theo1 bioactivation, streptavidin linkage to the ANP/Theo1-modified membrane was obtained, which is an indication of streptavidin capture.
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      PubDate: 2016-01-16T18:29:08Z
       
  • Systematic study of the chemical and hydrothermal stability of selected
           “stable” Metal Organic Frameworks
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): Karen Leus, Thomas Bogaerts, Jeroen De Decker, Hannes Depauw, Kevin Hendrickx, Henk Vrielinck, Veronique Van Speybroeck, Pascal Van Der Voort
      In this work, the hydrothermal and chemical stability towards acids, bases, air, water, and peroxides of Metal Organic Frameworks, that are commonly considered to be stable, is presented. As a proof of stability both the crystallinity and porosity are measured before and after exposure to the stress test. The major part of the MOFs examined in this study show a good hydrothermal stability except for UiO-67, NH2-MIL-101 (Al) and CuBTC. The chemical stabilities towards acids and bases show a similar tendency and an ordering can be proposed as: MIL-101(Cr) > NH2-UiO-66 > UiO-66 > UiO-67 > NH2-MIL-53 > MIL-53(Al)>ZIF-8 > CuBTC > NH2-MIL-101(Al). In the tests with H2O2 most materials behaved poorly, only the UiO-66 and NH2-UiO-66 frameworks show a good stability.
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      PubDate: 2016-01-16T18:29:08Z
       
  • High activity of mononuclear copper present in the framework of CuSiBEA
           zeolites in the selective catalytic reduction of NO with NH3
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): Rafal Baran, Teresa Grzybek, Thomas Onfroy, Stanislaw Dzwigaj
      CuxSiBEA zeolites (with x = 1–7.5 Cu wt %) prepared by a two-step postsynthesis method which consists in the first step of dealumination of parent BEA zeolite to obtain aluminum-free SiBEA support and then in the second step, of contacting the obtained material with an aqueous solution of copper nitrate, were used in this work as catalysts of SCR of NO with ammonia. XRD, TPR and FTIR investigations showed that up to 2 wt % of Cu was successfully incorporated into zeolite beta structure as framework mononuclear Cu(II). The FTIR of pyridine sorption revealed that the incorporation of copper into zeolite framework led to the creation of new Lewis acidic sites which were responsible for high activity of CuxSiBEA zeolite catalysts in SCR of NO with ammonia. The catalytic activity of CuxSiBEA in SCR of NO with ammonia used as a reducing agent strongly depends on the nature and environmental of copper in BEA structure. The Cu1.0SiBEA catalyst with predominantly framework Cu(II) was the most active and selective among the tested samples in wide temperature range. In contrast, the application of CuxSiBEA zeolite catalysts with higher Cu content (>than 2 wt % of Cu) containing a mixture of framework and extra-framework Cu(II) resulted in low NO conversion in SCR at high temperature range, as well as, the high concentration of undesired N2O in outgas stream. It indicates that octahedral Cu(II) and/or copper oxides present in extra-framework position of SiBEA zeolite promote at high temperature ammonia oxidation.
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      PubDate: 2016-01-16T18:29:08Z
       
  • Mesoporous silica-based carbon dot/TiO2 photocatalyst for efficient
           organic pollutant degradation
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): Chen Cheng, Deli Lu, Bin Shen, Yongdi Liu, Juying Lei, Lingzhi Wang, Jinlong Zhang, Masaya Matsuoka
      Carbon dots (CD) and Ti species were assembled in the mesoporous silica matrix by a one-pot co-condensation strategy. The CD and Ti in the silica matrix were demonstrated to interact in two ways: on the one hand, part of the carbon in CD was doped into the Ti species; on the other hand, CD worked as photosensitizers for Ti species. The synergy effect between CD and Ti in the silica matrix along with the unique physical properties of the composite including ordered pore channels, large surface area and wide-range light absorption from UV to near IR made this composite be an excellent photocatalyst, as demonstrated by the photocatalytic degradation of azo dye acid orange 7. In addition to the degradation of organic pollutant, this newly developed mesoporous composite is expected to have promising applications in various areas related to environment and energy such as photoreduction of CO2 and photocatalytic H2 production.
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      PubDate: 2016-01-16T18:29:08Z
       
  • Influence of partial dealumination of BEA zeolites on physicochemical and
           catalytic properties of AgAlSiBEA in H2-promoted SCR of NO with ethanol
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): Nataliia O. Popovych, Pavlo I. Kyriienko, Sergiy O. Soloviev, Svitlana M. Orlyk, Stanislaw Dzwigaj
      The two-step postsynthesis method allows obtaining AlSiBEA zeolites with different degree of dealumination (Si/Al = 100 and 200). Physicochemical properties (crystallinity, hydroxyl group coverage, acidic sites and nature of silver species) of AlSiBEA and AgAlSiBEA were investigated by XRD, DR UV–vis, XPS, TEM and FT-IR with CO and pyridine as probe molecules. Catalytic properties of the zeolites were studied in the process of selective reduction of NO with ethanol in the presence of hydrogen in the reaction mixture. It was shown that level of H2-promoting effect on the SCR-process depends on the dealumination degree of Ag-containing BEA zeolites and greater effect is observed for the catalysts with higher concentration of Lewis acidic sites.
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      PubDate: 2016-01-12T11:01:03Z
       
  • Development of antimicrobial hybrid mesoporous silver
           phosphate–pectin microspheres for control release of levofloxacin
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): Bernardo Bayón, Verónica Bucalá, Guillermo R. Castro
      Pectin was used as nucleation agent in the synthesis of spherical mesoporous Ag3PO4 microspheres for the development of dual antimicrobial carrier containing a fluoroquinolone. The hybrid Ag3PO4–pectin microspheres were characterized by biophysical methods using optical, scanning and transmission electronic microscopies, X-ray diffraction and energy dispersive analysis, differential scanning calorimetry, laser diffraction, and molecular gas adsorption (Brunauer–Emmett–Teller). Scanning electron microscopy (SEM) images of silver phosphate microspheres without pectin displayed heterogeneous surface, bimodal size distribution between 0.9–1.0 μm and 1.5–1.8 μm with 20% and 25% population yield respectively and high amount of salt detritus. Meanwhile, SEM microphotographies of silver phosphate microspheres synthesized in presence of pectin showed a drastic change of particle morphology, homogenous surface, narrow size particle distribution in the 1.3–1.5 μm range with 90% population yield, 20–30% pore size increase and without debris. X-ray diffraction analysis of silver phosphate microspheres showed the same crystal profile in presence or absence of pectin suggesting no changes in the crystalline structure of Ag3PO4 by the addition of the biopolymer was made. Effect of silver phosphate hybrid microspheres loaded with levofloxacin tested against Escherichia coli and Staphylococcus aureus showed strong bactericidal activity compared with the bacteriostatic effect of free levofloxacin. The results are suggesting that hybrid Ag3PO4–pectin microspheres containing levofloxacin can be used as effective antimicrobial against several microorganisms, making them applicable to diverse medical devices and for antimicrobial control systems. The Ag3PO4–pectin hybrid microspheres are advantageous since they are synthesized by green chemistry methodology under standard laboratory conditions, do not requiring purification steps, the technique is highly reproducible and they are available for drug loading and specific target tailoring. The main advantage of Ag3PO4–pectin microspheres is the synergic antimicrobial activity of the silver ion and the antibiotic in the same microdevice acting as biocide matrix and also as carrier for levofloxacin.
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      PubDate: 2016-01-12T11:01:03Z
       
  • Nanoporous CuO ribbons modified by Au nanoparticles through chemical
           dealloying and calcination for CO oxidation
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): Xiaolong Zhang, Guijing Li, Sen Yang, Xiaoping Song, Zhanbo Sun
      The ultrafine nanoporous CuO ribbons modified by Au nanoparticles are prepared through simply dealloying the melt-spun Al–Cu–Au alloys combined the subsequent calcination in air. A nanoporous Cu (Au) solid solution ribbon is constructed as the removal of Al from the precursory alloys. After calcined at high temperature, Cu is oxidized to CuO with a porous structure and the in situ generated Au nanoparticles embed in ligaments, resulting in the formation of nanoporous CuO/Au composites with a pore size about 25 nm. The experiment results indicate that the composites have large surface area, high activity and stability. And the CO conversion rate can reach 100.0% just at 180 °C. According to XPS (X-ray photoelectron spectroscopy) results, the superior performance at low temperature is ascribed to the presence of Au+1 species and the interfacial interaction between Au nanoparticles and CuO ligaments. The present work can contribute to the development of the porous catalytic materials with high performances and low cost.
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      PubDate: 2016-01-12T11:01:03Z
       
  • Investigation of bromine atom transfer mechanism from an alkyl bromide
           molecule to an O-bonded alkyl group in a FAU zeolite by the ONIOM method
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): D.K. Papayannis, K.D. Papavasileiou, V.S. Melissas
      The details of the bromine atom transfer mechanism from an ethyl bromide molecule to an O-bonded alkyl group, attached to the FAU zeolite wall, were elucidated, by means of Quantum Mechanical and Molecular Mechanical (QM/MM) calculations. The investigation of this mechanism has been established on the 84T model cluster of faujasite zeolite with the help of the ONIOM approach, utilizing three-layer ONIOM3(B3LYP/6-31 + G(d,p):HF/6-31G:UFF), ONIOM3(M06-2X/6-31 + G(d,p):HF/6-31G:UFF) and ONIOM3(MP2(full)/6-31 + G(d,p):HF/6-31G:UFF) schemes. Our results indicate that the reaction proceeds via a ring structure formation path, where the ethyl bromide molecule is strongly attracted to both the alkyl group and the nearby Si bridging lattice O atom. Interaction energies for the O-bonded alkyl (ethyl or isopropyl) group linked to an ethyl bromide molecule in a FAU pore according to the ONIOM3(MP2(full)/6-31+G(d,p):HF/6-31G:UFF) calculation are approximately −18.3 and −19.3 kcal mol−1, respectively. In addition, at the same level of theory, the bromine atom shift from the ethyl bromide molecule to the adjacent O-bonded ethyl or isopropyl group, forming a new alkyl bromide and a new ethyl radical, are characterized by an activation barrier of 25.1 and 17.9 kcal mol−1, respectively, relative to the reagent complex.
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      PubDate: 2016-01-12T11:01:03Z
       
  • Synthesis and structural characterization of microporous N4O4-donor Schiff
           base macrocycle: Study of host–guest interactions and iodine
           sorption
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): Tomislav Balić, Berislav Marković, Jarosław Jaźwiński, Dubravka Matković-Čalogović
      A novel N4O4-donor macrocyclic Schiff base (1,6,20,25-tetraaza-2,5:8,9:17,18:21,24:27,28:36,37-hexabenzo-10,16,29,35-tetraoxa-cyclooctatriakonta-1,6,20,25-tetraen) (1) was prepared by a [2 + 2] cyclocondensation reaction of the corresponding dialdehyde and diamine. The crystal and molecular structure was determined by the single crystal X-ray diffraction analysis, and the compound was additionally characterized by IR, Raman and NMR spectroscopy, thermal and elemental analysis. In the crystal the molecules of the macrocycle are connected by a series of weak hydrogen bonds into tubular structures, thus forming an open porous structure with nanometre sized pores (around 18% of the void volume). Recrystallization of 1 from chloroform and dichloromethane led to the formation of the chloroform solvate (1×CLF), and the dichloromethane solvatomorph (1×DCM). The chloroform solvate was treated with iodine vapour in a sealed chamber thus forming a stable iodine host–guest complex (1×I 2 ). From the spectroscopic, crystal structure, and thermal analysis studies of 1×CLF, 1×DCM and 1×I 2 it can be deduced that the compound forms stable host–guest complexes without any changes in the organic framework. The host:guest ratio was found to be 1:1, 1:3 and 2:1 for chloroform, dichloromethane and iodine complexes, respectively. The adsorption studies of activated 1×CLF showed a small uptake of CO2 at 298 K.
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      PubDate: 2016-01-12T11:01:03Z
       
  • Mechanical characterization of aerogel materials with digital image
           correlation
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): Rami Haj-Ali, Rami Eliasi, Victor Fourman, Chen Tzur, Galit Bar, Eitan Grossman, Ronen Verker, Raz Gvishi, Irina Gouzman, Noam Eliaz
      Silica aerogels are ultralow density materials with nano-sized skeleton network of pores. Their high brittle nature presents a major challenge for mechanical testing and a need exists for novel testing methods. Two new mechanical setups and testing techniques are proposed for measuring the aerogel elastic mechanical properties. Both techniques employ full-field Digital Image Correlation (DIC) for surface deformation measurements. The first setup uses disk compression experiment, known as diametral compression test (Brazilian disk). However, the elastic properties of the material cannot be obtained directly. Instead, an inverse mechanics computational scheme, using both a finite element (FE) model and analytical solution, is proposed. The second direct testing setup is uniaxial compression of rectangular-shaped blocks. The Young's modulus and Poisson's ratio are extracted directly from the experimental stress–strain curves. Our results of tested samples show the relation between the density and the Young's modulus to coincide with previously published trends. The direct and iterative inverse-mechanics solution methods agree well with each other. The Poisson's ratio is found to be independent of the material apparent density. Comparisons between the two methods and recommendations for expanding the disk testing approach to fracture toughness are discussed.
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      PubDate: 2016-01-12T11:01:03Z
       
  • Spectroscopy and relaxation dynamics of salicylideneaniline derivative
           aggregates encapsulated in MCM41 and SBA15 pores
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): Noemí Alarcos, Félix Sánchez, Abderrazzak Douhal
      We report on steady-state and picosecond time-resolved emission studies of (E)-2-(2’-hydroxybenzyliden)amino-4-nitrophenol (HBA-4NP) interacting with MCM41, Al-MCM41 and SBA15. In these materials, the molecule shows spectral changes, with a broadening and shifts of absorption and emission bands, which depend on the concentration used in the preparation of the samples, indicating the aggregates formation. These caged monomers (M), H- and J-aggregates are in enol form at S0 and in keto one at S1, as a result of an excited-state intramolecular proton transfer (ESIPT) reaction. The K lifetime of the caged M is longer (3 ns) than the observed in solution (14 ps), due to the confinement effect on the radiationless pathways. The K lifetimes of J- and H-aggregates are 600 and 100 ps, respectively, and their populations and stability depend on pore size and chemical composition (in terms of Brönsted acidity) of the host. For MCM41 and Al-MCM41 ones, the formation of H- and J-aggregates is higher than using SBA15. This is due to a better encapsulation by the formers (85–95% MCM41/Al-MCM41 vs 60% SBA15). Doping MCM41 by Al allows more J-aggregates as result of strong interaction between the guest molecules and the Al-MCM41 framework. Thus, modulating the topological and structural properties of the mesoporous material leads to the formation of different encapsulated species, which could be of great interest to design nanophotonics devices based on this kind of materials.
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      PubDate: 2016-01-12T11:01:03Z
       
  • Thermoporosimetry of n-alkanes for characterization of mesoporous SBA-15
           silicas – Towards deeper understanding the effect of the probe
           liquid nature
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): D. Majda, K. Tarach, K. Góra-Marek, A. Michalik-Zym, B.D. Napruszewska, M. Zimowska, E.M. Serwicka
      Thermoporosimetry (TPM), based on DSC measure melting point depression of n-alkane confined in mesopores, can provide very useful information about the porous properties of studied material as long as the obtained results are well understand and described. In this paper we reported original and detailed results concerning the nature of the alkanes confined inside the channels of a series of mesoporous SBA-15 silicas, differing by size of the unit cell. The complex character of pore size distribution profiles, known from our earlier works, was investigated and finally evaluated. For the first time the impact of such factors as solid to liquid mass ratio, the degree of pore cover and freezing time on the n-alkane TPM results was explained. Additionally, the even-odd effect on alkane TPM was evaluated. Based on FT-IR investigations the interactions between the probe molecules and the pore walls were found to be negligible.
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      PubDate: 2016-01-12T11:01:03Z
       
  • Co-templated synthesis of polymorph A-enriched zeolite beta
    • Abstract: Publication date: 15 May 2016
      Source:Microporous and Mesoporous Materials, Volume 226
      Author(s): Tingting Lu, Ruren Xu, Wenfu Yan
      The initial mixture containing fully hydrolysed tetraethyl orthosilicate (TEOS) and tetraethylammonium hydroxide (TEAOH) solution was treated either by heating at 80 °C or by freeze-drying. After adding an appropriate amount of concentrated hydrofluoric acid, the resulting mixture was crystallized at 150 °C. The heating treated mixture produced polymorph A-enriched zeolite beta while freeze-drying treated mixture gave only normal zeolite beta. The 13C magic angle spinning nuclear magnetic resonance (MAS NMR) analysis and thermogravimetric analysis (TGA) indicated that a partial decomposition of TEAOH to generate triethylamine (TEA) occurred during the heating dehydration process, which was the only difference compared with the freeze-drying process. Together with the reduced TEAOH, different monoamines as a co-template directed the polymorph A-enriched zeolite beta with the freeze-drying process. Diamines as a co-template directed only the normal zeolite beta. The synthesis cost of polymorph A-enriched zeolite beta can be significantly reduced by lowering the usage of expensive TEAOH and using cheaper monoamines.
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      PubDate: 2016-01-12T11:01:03Z
       
  • De-agglomeration of IZM-2 zeolite crystals by post-synthetic treatment
    • Abstract: Publication date: 1 May 2016
      Source:Microporous and Mesoporous Materials, Volume 225
      Author(s): Yunxiang Li, Haoquan Zheng, Yifeng Yun, Diana Bernin, Mattias Edén, Xiaodong Zou, Feifei Gao
      Highly intergrown nanocrystals are commonly observed in zeolite samples, and the densely packed agglomerates may result in small secondary porosity, which restricts the advantage of hierarchical structures. In this work we take IZM-2 zeolite as an example to demonstrate a post-treatment method with diluted hydrofluoric acid solution, which de-agglomerates intergrown zeolite nanocrystals and improves the secondary porosity. The treated samples preserve high crystallinity, similar framework composition and distinctively higher external surface area compared to the agglomerated ones. The results show that this treatment is an effective method for de-agglomeration of intergrown nanocrystals without affecting the original framework.
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      PubDate: 2016-01-04T07:54:21Z
       
  • The effect of digestive activity of pig gastro-intestinal tract on
           zeolite-rich rocks: An in vitro study
    • Abstract: Publication date: 1 May 2016
      Source:Microporous and Mesoporous Materials, Volume 225
      Author(s): Mariano Mercurio, Piergiulio Cappelletti, Bruno de Gennaro, Maurizio de Gennaro, Fulvia Bovera, Francesco Iannaccone, Celestino Grifa, Alessio Langella, Vincenzo Monetti, Luigi Esposito
      Two zeolite-rich rock samples extracted from Campanian Ignimbrite tuff quarries, southern Italy, usually used as binding and anticaking agents in animal feeding, were characterized and tested in terms of their resistance in stomach, small and large intestine of pig, using a three step in vitro digestibility trial. The mineralogical composition and major and trace-elements analysis were performed after each digestion step using XRPD and ICP-OES techniques. The main zeolite phases identified are phillipsite and chabazite. Results showed that in vitro physical-chemical conditions (pH 2–3 and T 39 °C) the release of Pb and other elements from the zeolite structure is extremely low and due to the limited breakdown of the zeolite framework and glass/amorphous matter hydrolysis, by the gastric liquids. This aspect also suggests that zeolites, after the total permanence in the animal body digestive tract, can further perform their important function of cation exchanger, with also relevant relapses on the growth and health of the animal species, as well as on the environment. Moreover, the contact of zeolite material with liquids of small and large intestine leads to negligible release of undesirable elements, which are far less than those envisaged by the European Regulations.
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      PubDate: 2016-01-04T07:54:21Z
       
  • Periodic mesoporous organosilica (PMO) containing bridged succinamic acid
           groups as a nanocarrier for sulfamerazine, sulfadiazine and famotidine:
           Adsorption and release study
    • Abstract: Publication date: 1 May 2016
      Source:Microporous and Mesoporous Materials, Volume 225
      Author(s): Surendran Parambadath, Aneesh Mathew, Mary Jenisha Barnabas, Kummara Madhusudana Rao, Chang-Sik Ha
      Periodic mesoporous organosilica (PMO) with a bridged amine framework and a pendant succinamic acid group (SA-PMO-5) was synthesised using a sol–gel and post modification process. The bridged amino functionality was introduced to the pore wall of the PMO (MA-PMO-5) using a silsesquioxane precursor, N,N-bis[3-(triethoxysilyl)propyl]amine (BTMSA), along with tetramethyl orthosilicate (TMOS). The succinamic acid functionality was tailored by the ring opening reaction of succinic anhydride with the bridged amine. The physico-chemical properties of SA-PMO-5 were determined by a range of spectroscopic analyses. X-ray diffraction, scanning electron microscopy and transmission electron microscopy showed that the MA-PMO-5 and SA-PMO-5 possessed mesoscopically ordered, hexagonal symmetry as well as well-defined morphologies. The N2 sorption experiment showed the MA-PMO-5 and SA-PMO-5 had a large surface area (704 and 623 m2 g−1), acceptable pore diameter (3.2 and 2.4 nm) and pore volume (0.56 and 0.47 cm3 g−1) to accommodate the guest molecules inside the pore channels. Organic functionalisation was determined successfully by Fourier transform infrared spectroscopy and 13C cross-polarisation magic angle spinning (CP-MAS) NMR spectroscopy. 29Si MAS NMR spectral analysis revealed the silicon environment of the final material. Sulfamerazine (SMR), sulfadiazine (SDZ) and famotidine (FAMO) adsorption as well as the release properties from the MA-PMO-5 and SA-PMO-5 were investigated at pH 4 and 7.4. The high adsorption and delayed release properties exhibited by SA-PMO-5 were attributed to the strong interaction between succinamic acid functionality with the drug molecules.
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      PubDate: 2016-01-04T07:54:21Z
       
  • Lanthanum-impregnated zeolite modified carbon paste electrode for
           determination of Cadmium (II)
    • Abstract: Publication date: 1 May 2016
      Source:Microporous and Mesoporous Materials, Volume 225
      Author(s): A. Ismail, A. Kawde, O. Muraza, M.A. Sanhoob, A.R. Al-Betar
      We report the hydrothermal synthesis of mordenite zeolite in the absence of organic structuring directing agent (OSDA). The mordenite (MOR) zeolite with molar composition 6Na2O:Al2O3:30SiO2:780H2O was characterized by XRD, SEM, EDX, and NMR. It was further impregnated with lanthanum and was used in the construction of zeolite modified carbon paste electrode by mixing with different amounts of graphite and paraffin oil to form a paste. The paste composite with the ratio 65:5:30 (graphite:zeolite:paraffin) displayed the best electrochemical behavior in the cyclic voltammetry of K4Fe(CN)6 and was hence used for the detection of Cd (II) ions.
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      PubDate: 2016-01-04T07:54:21Z
       
  • Synthesis of SAPO-34 nanoplates via hydrothermal method
    • Abstract: Publication date: 1 May 2016
      Source:Microporous and Mesoporous Materials, Volume 225
      Author(s): Hong Yang, Xiaohui Liu, Guanzhong Lu, Yanqin Wang
      In this work, SAPO-34 nanoplates were synthesized by dissolving pseudoboehmite and silica sol in an aqueous solution of tetraethyl ammonium hydroxide (TEAOH) firstly, then adding H3PO4 in the above mixture, and finally following with hydrothermal treatment. SEM and TEM observations showed that the SAPO-34 nanoplate possed a uniform size (200–400 nm) with the thickness of 40–50 nm. Detailed analysis revealed that the dissolution or depolymerization of the silica sol in alkaline conditions was critical for the formation of SAPO-34 nanoplates. Furthermore, PEG was introduced during the synthesis process as porogens and mesoporous SAPO-34 nanoplates were obtained without disturbing the formation of nanoplates. The catalytic properties of SAPO-34 were tested in the dehydration of fructose into 5-hydroxymethylfurfural (HMF). All the nanoplate catalysts showed excellent catalytic performance compared with conventional cube-like SAPO-34, and the mesoporous structure could further facilitate mass transfer.
      Graphical abstract image

      PubDate: 2016-01-04T07:54:21Z
       
  • Templated synthesis of 3D hierarchical porous Co3O4 materials and their
           NH3 sensor at room temperature
    • Abstract: Publication date: 1 May 2016
      Source:Microporous and Mesoporous Materials, Volume 225
      Author(s): Baofeng Wu, Linlin Wang, Hongyuan Wu, Kan Kan, Guo Zhang, Yu Xie, Ye Tian, Li Li, Keying Shi
      In this paper, 3D hierarchical porous Co3O4 materials (HPCo) were synthesized via a PS spheres templated transformation route. This novel 3D structure contained not only plenty of interconnecting macropores and mesopores, but also a large amount of irregular structure defects. The Co-4 synthesized by 0.4 M Co(NO3)2·6H2O concentrations solution had the largest specific surface area of 58.75 m2 g−1 and a average particle size of 20 nm. The optimized sample presents excellent sensing performance to NH3 gas at room temperature (RT = 21 °C) with the highest sensitivity (146% to 100 ppm), fast response time (2 s to 100 ppm), and a low detection limit of 0.5 ppm. Such superior properties were attributed to the unique hierarchical porous structure, large specific surface area, excellent chemisorbed ability to oxygen species and good catalytic activity of Co3O4 nanomaterials.
      Graphical abstract image

      PubDate: 2016-01-04T07:54:21Z
       
  • Facile synthesis of nitrogen and sulfur co-doped graphene-like carbon
           materials using methyl blue/montmorillonite composites
    • Abstract: Publication date: 1 May 2016
      Source:Microporous and Mesoporous Materials, Volume 225
      Author(s): Qingze Chen, Hongmei Liu, Runliang Zhu, Xin Wang, Shuangyin Wang, Jianxi Zhu, Hongping He
      Heteroatom-doped carbon materials are currently drawing increasing interest because they show remarkable performance when applied in lithium-ion batteries, supercapacitors, and fuel cells. In this work, a facile method was developed to synthesize N and S co-doped graphene-like carbon materials using montmorillonite (Mt) after the adsorption of methyl blue (MB). The MB–Mt composites were pyrolyzed in a N2 atmosphere to carbonize the adsorbed MB within the interspace of Mt. The resulting pyrolyzed carbon/Mt composite showed a basal spacing value of approximately 0.44 nm, close to the thickness of a single graphene sheet, suggesting the formation of graphene-like carbon materials within the interspace of Mt. Then, the carbon/Mt composite was demineralized by acid washing to liberate the carbon materials. Transmission electron microscopy and atomic force microscopy results directly showed the morphology of the resulting carbon material, i.e., the stacking of thin carbon sheets. Raman spectra showed the simultaneous presence of both a D-band and G-band for the obtained carbon materials, and their intensity ratio decreased with increasing pyrolysis temperature. X-ray photoelectron spectroscopy results indicated the presence of C, S, and N atoms in the carbon materials, and the doping sites of the S and N atoms were proposed. Finally, the obtained carbon materials showed interesting electrocatalytic activity for the oxygen reduction reaction, suggesting their potential application as efficient metal-free electrocatalysts in fuel cells. Our work synthesized N and S co-doped graphene-like materials with interesting electrocatalytic activity, which proved that the templated synthesis method could be a facile approach to synthesize various heteroatom-doped graphene-like carbon materials.
      Graphical abstract image

      PubDate: 2016-01-04T07:54:21Z
       
  • The predictive power of classical transition state theory revealed in
           diffusion studies with MOF ZIF-8
    • Abstract: Publication date: 1 May 2016
      Source:Microporous and Mesoporous Materials, Volume 225
      Author(s): Christian Chmelik, Jörg Kärger
      Knowledge of the adsorption isotherm is demonstrated to be sufficient for predicting the concentration dependence of the diffusivity of light hydrocarbons in MOF ZIF-8. Guest molecules considered include saturated and unsaturated hydrocarbons and alcohols. Calculations are based on the application of the classical transition state theory (TST). The predictions cover concentration dependences of up to two orders of magnitude in transport diffusion and of one order in self-diffusion. In agreement with TST, self- and corrected (Maxwell–Stefan) diffusivities are seen to coincide.
      Graphical abstract image

      PubDate: 2015-12-31T00:52:51Z
       
  • Metal zirconium phosphate macroporous monoliths: Versatile synthesis,
           thermal expansion and mechanical properties
    • Abstract: Publication date: 1 May 2016
      Source:Microporous and Mesoporous Materials, Volume 225
      Author(s): Yang Zhu, Kazuyoshi Kanamori, Nirmalya Moitra, Kohei Kadono, Shugo Ohi, Norimasa Shimobayashi, Kazuki Nakanishi
      A versatile synthetic method has been developed for the fabrication of metal zirconium phosphate (MZP) macroporous monoliths via a sol–gel process accompanied by phase separation. More than 30 kinds of MZP monolithic polycrystalline monoliths with co-continuous macroporous structure have been synthesized by simply adding the target metal salt in the starting solution with optimized compositions. Glycerol, due to its high boiling point, plays the key role as the solvent to prevent metal salt from recrystallization, allowing a homogeneous distribution of metal salts over the polymerizing zirconium phosphate network. Hierarchically porous polycrystalline strontium zirconium phosphate (SrZrP) monolith has been obtained when the dried gel was calcined at 1000 °C. Very low thermal expansion (coefficient of thermal expansion (CTE) as 1.4 × 10−6 K−1) over a wide temperature range (38 °C–1000 °C) together with good mechanical properties (flexural modulus as 8.0 GPa from 3 point bending test and Young's modulus as 1.9 GPa from uniaxial compression test) has been demonstrated, while high porosity (43%) due to the presence of macropores reduces bulk density. As compared with dense ceramics of the same composition, the CTE value is lower and can be attributed to the presence of nanometer-sized small pores, which absorbs the anisotropic thermal expansion of each crystallite in the macropore skeletons at elevated temperatures.
      Graphical abstract image

      PubDate: 2015-12-31T00:52:51Z
       
  • Synthesis and gas adsorption properties of mesoporous
           silica-NH2-MIL-53(Al) core–shell spheres
    • Abstract: Publication date: 1 May 2016
      Source:Microporous and Mesoporous Materials, Volume 225
      Author(s): Sara Sorribas, Beatriz Zornoza, Pablo Serra-Crespo, Jorge Gascon, Freek Kapteijn, Carlos Téllez, Joaquín Coronas
      Ordered mesoporous silica-NH2-MIL-53(Al) core–shell spheres of about 4 μm in diameter have been synthesized by seeding the corresponding mesoporous silica spheres (MSSs) with crystals of NH2-MIL-53(Al) and subsequent secondary crystal growth into a MOF shell. The morphology of the particles was analyzed by SEM, while TGA, EDX and XRD characterizations gave information on the composition and structure of this material and the activation of the MOF. N2 adsorption analysis revealed that the NH2-MIL-53(Al) shell controlled the access of guest molecules into the hydrophilic silica mesoporous structure, while the breathing behavior of the microporous NH2-MIL-53(Al) shell was confirmed by CO2 adsorption isotherms.
      Graphical abstract image

      PubDate: 2015-12-31T00:52:51Z
       
  • Pore sizes and directionality in microcapillaries from angular
           double-pulsed-field-gradient NMR
    • Abstract: Publication date: 1 May 2016
      Source:Microporous and Mesoporous Materials, Volume 225
      Author(s): Darya Morozov, Leah Bar, Nir Sochen, Yoram Cohen
      Angular double-pulsed-field gradient (d-PFG) MR methodology is increasingly used to non-invasively obtain pore sizes in opaque chemical and biological systems. In such MR experiments, the angular dependency of the signal at zero mixing time, through modeling, can be used to extract the pore size. In many systems not only the pore sizes but also their directions are of importance. Before applying d-PFG NMR to complex systems, it is of value to challenge the ability of the methodology to extract these microstructural parameters in samples where the ground truth is known. In the present study we explored whether modeling of the signal in angular d-PFG NMR experiments at zero mixing time, can simultaneously provide the size and the direction of tilted compartments with little prior knowledge. We showed that the angular d-PFG MR methodology enables simultaneous extraction of the pore size and the direction of mono-dispersed phantoms and of phantoms where the restricted compartments have different pore sizes. However, we found that in phantoms with two or more pore sizes, only averaged pore sizes were extracted for large azimuthal and polar angles.
      Graphical abstract image

      PubDate: 2015-12-31T00:52:51Z
       
  • Synthesis of nanosized Silicalite-1 in F−media
    • Abstract: Publication date: 1 May 2016
      Source:Microporous and Mesoporous Materials, Volume 225
      Author(s): Kun Jiao, Xiangyu Xu, Zhi Lv, Jiaqing Song, Mingyuan He, Hermann Gies
      This paper reports on the successful crystallization of monodisperse, highly crystalline, nanosized zeolite Silicalite-1 crystals in fluoride media by using an active silica gel as silica source and tetrapropylammonium fluoride as structure directing agent. The synthesis procedure is hydrothermal dynamic crystallization. The silica/water ratio and synthesis temperature were reduced to optimize the number of crystal nuclei and control the rate of crystallization for obtaining nanosized zeolite crystals. Meanwhile, F− ions were used to partly replace OH− ions in the synthesis system to obtain zeolite products with high crystallinity. Analytical results of XRD-, SEM-, Dynamic Light Scanning- (DLS) IR-, Simultaneous Thermal Analysis- (STA) and N2 adsorption and desorption experiments show that the average particle size of zeolite Silicalite-1 product is about 45 nm and shows high crystallinity. The F− containing Silicalite-1 zeolite sample was compared with an industrial ZSM-5 zeolite sample and it shows obvious advantages in both reduced particle size and enhanced crystallinity.
      Graphical abstract image

      PubDate: 2015-12-31T00:52:51Z
       
  • Enhanced photocatalytic activity of TiO2 supported on zeolites tested in
           real wastewaters from the textile industry of Ethiopia
    • Abstract: Publication date: 1 May 2016
      Source:Microporous and Mesoporous Materials, Volume 225
      Author(s): Kiros Guesh, Álvaro Mayoral, Carlos Márquez-Álvarez, Yonas Chebude, Isabel Díaz
      A series of selected TiO2-Zeolite hybrid photocatalytic materials have been systematically synthesized and analyzed. The synthesized samples were characterized by X-ray diffraction (XRD), elemental analysis (ICP-OES), N2 adsorption–desorption isotherms, diffuse reflectance UV–Vis spectroscopy (DRS), and transmission electron microscopy (STEM/HAADF/EDS/EELS). The photocatalytic activity of the samples was tested for the degradation of methyl orange (MO) and real wastewaters from the textile industry of Ethiopia. A 10% loaded TiO2-Zeolite Y (CBV 760) yielded up to 20 times higher mass normalized turnover rate (TORm) than pristine TiO2. The reusability of this photocatalyst was tested and only a 5% decrement was observed after three cycles. Furthermore, the photocatalytic activity was tested for real textile wastewater of Ethiopia resulting in 84 and 49% removal of total organic carbon (TOC) using 10% loaded TiO2-Zeolite Y and pristine TiO2, respectively. The enhanced photocatalytic activity of the hybrid system is attributed to the dual role of the zeolite surface and to the electronic modification of the TiO2 photocatalyst.
      Graphical abstract image

      PubDate: 2015-12-31T00:52:51Z
       
  • Unraveling the non-classic crystallization of SAPO-34 in a dry gel system
           towards controlling meso-structure with the assistance of growth
           inhibitor: Growth mechanism, hierarchical structure control and catalytic
           properties
    • Abstract: Publication date: 1 May 2016
      Source:Microporous and Mesoporous Materials, Volume 225
      Author(s): Jingwei Zheng, Weiping Zhang, Zhiting Liu, Qisheng Huo, Kake Zhu, Xinggui Zhou, Weikang Yuan
      Understanding silicoaluminophosphate formation mechanism lays the foundation for their structure manipulation via crystallization process control. Crystallization of SAPO-34 from a dry gel using tetraethyl ammonium hydroxide as structure-directing agent was monitored to unravel the formation mechanism. The initial gel was found to form a lamellar precursor first, which subsequently underwent phase transformation to discrete SAPO-34 nanocrystallites. The nanocrystallites thereafter mutually aligned with neighboring ones via a non-classic oriented attachment growth mechanism, affording large crystals as a result of grain boundary elimination. A new protocol to prepare hierarchical SAPO-34 was designed by hindering the aggregation of primary nanocrystallites with a growth inhibitor 1,2,3-hexanetriol. The structure of hierarchical SAPO-34 was characterized by XRD, N2 physisorption, mercury intrusion, SEM, TEM, as well as 27Al, 29Si, 31P MAS NMR spectra and compared with a conventional SAPO-34. More Si islands were formed via combined SM3 (Al+P pairs substitution by 2Si) and SM2 (P substitution by Si) mechanism for hierarchical SAPO-34 as Si was not fully incorporated into the precursor lamellar phase. NH3-TPD showed that hierarchical SAPO-34 has comparable acidic strength to conventional SAPO-34. The obtained hierarchical SAPO-34 is comprised of <100 nm crystallites and possesses well-connected mesopores, both factors are crucial to mass transfer in zeotype materials. Hierarchical SAPO-34 exhibited a 1.5 times lifetime increase in catalytic chloromethane to olefin conversion with respect to a conventional counterpart.
      Graphical abstract image

      PubDate: 2015-12-31T00:52:51Z
       
  • 129Xenon NMR: Review of recent insights into porous materials
    • Abstract: Publication date: 1 May 2016
      Source:Microporous and Mesoporous Materials, Volume 225
      Author(s): Erika Weiland, Marie-Anne Springuel-Huet, Andrei Nossov, Antoine Gédéon
      This paper presents a comprehensive review of the recent advances in xenon-129 nuclear magnetic resonance (NMR) measurements. In the past thirty years, 129Xe NMR has proved to be an efficient technique to investigate the structure of porous solids and several extensive reviews on the subject are available in the literature. The main advantage of 129Xe NMR is the high sensitivity of the xenon atom to its local environment. Using optical pumping techniques for the production of hyperpolarized (HP) xenon has led to an increase in sensitivity of several orders of magnitude. This development has opened the way to explore the internal structure and the porosity of a wide range of new advanced materials. This review which covers the period, 2005 up to now, starts with a description of the basic theory of xenon-NMR. It presents a basic overview of thermally and hyperpolarized xenon NMR technique followed by the recent NMR developments on various classes of porous materials.
      Graphical abstract image

      PubDate: 2015-12-31T00:52:51Z
       
  • Cellulose biotemplates for layered double hydroxides networks
    • Abstract: Publication date: 1 May 2016
      Source:Microporous and Mesoporous Materials, Volume 225
      Author(s): S.S.Liji Sobhana, Dhani Raj Bogati, Mehedi Reza, Jan Gustafsson, Pedro Fardim
      Synthesis of porous network structures of layered double hydroxides (LDH) has been studied using microcrystalline cellulose (MCC) as a hard template. LDH was synthesized using cellulose as biotemplate and post treated by microwave hydrothermal treatment (MWHT). The prepared LDHs were thoroughly characterized by Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy, X-ray Diffraction (XRD) studies, and Thermogravimetric (TGA) analysis, which proved the formation of LDH structure in the presence and absence of MCC as templates. The morphological structures of the composite materials were analyzed by Scanning Electron Microscopy (SEM), which showed that the LDH formed in the presence of cellulose had porous network structures, while LDH particles synthesized in the absence of the MCC exhibited a hexagonal platelet-like morphology. Energy Dispersive X-ray (EDX) measurements confirmed the presence of essential elements in the particles. TEM showed the fibrillar nature and size reduction of the particles. The surface area of the material was measured by Brunauer–Emmett–Teller (BET) analysis, exhibiting a twofold increase in surface area and increased specific pore volume in comparison with particles synthesized in absence of cellulose and thus showcasing the potential of MCC as templates for production of porous LDH with high surface area (152 m2/g). Further, the adsorption capacities of the materials were evaluated with orange II dye.
      Graphical abstract image

      PubDate: 2015-12-31T00:52:51Z
       
  • Synthesis of Pd@ZIF-8 via an assembly method: Influence of the molar
           ratios of Pd/Zn2+ and 2-methylimidazole/Zn2+
    • Abstract: Publication date: 1 May 2016
      Source:Microporous and Mesoporous Materials, Volume 225
      Author(s): Hong Jiang, Qing Yan, Rizhi Chen, Weihong Xing
      Pd@ZIF-8 nanoparticles with uniform size and morphology were prepared via an assembly method that enables the crystallization of ZIF-8 in methanol in the presence of polyvinylpyrrolidone (PVP)-modified Pd nanoparticles. The molar ratios of Pd/Zn2+ and 2-methylimidazole (Hmim)/Zn2+ are important parameters affecting the physical and catalytic properties of the Pd@ZIF-8. The catalytic activities of the hybrid catalysts were evaluated by the hydrogenation of p-nitrophenol to p-aminophenol. The results indicate that the increase of Pd loading and p-nitrophenol conversion can be tuned by adding more amounts of PVP-Pd colloid, but a suitable amount of PVP-Pd (Pd/Zn2+ ≤ 0.012) is helpful to the control of particle size of Pd@ZIF-8 and encapsulation of the Pd nanoparticles within the ZIF-8 crystals. Pd@ZIF-8 catalysts prepared with excessive or equal molar of Hmim relative to Zn2+ have similar morphology and uniform particle size, where the Pd nanoparticles are fully confined within the ZIF-8 crystals without aggregation. Furthermore, the Pd@ZIF-8 catalysts exhibit the better catalytic performance for the p-nitrophenol hydrogenation owing to the high loading of well-dispersed Pd nanoparticles with the decreased Hmim/Zn2+ molar ratio. This work would aid the development of high-performance Pd@ZIF-8 catalysts.
      Graphical abstract image

      PubDate: 2015-12-26T23:28:38Z
       
  • Catalytically active Pt nanoparticles immobilized inside the pores of
           metal organic framework using supercritical CO2 solutions
    • Abstract: Publication date: 1 May 2016
      Source:Microporous and Mesoporous Materials, Volume 225
      Author(s): Kiyoshi Matsuyama, Momoe Motomura, Takafumi Kato, Tetsuya Okuyama, Hiroyuki Muto
      Pt nanoparticles were successfully immobilized inside the pores of a metal organic framework (MOF) like MIL-101(Cr) using supercritical carbon dioxide (scCO2), without Pt nanoparticles aggregating on the external surfaces of framework. After its preparation in a particular solvent, the internal surface area of MIL-101(Cr) increased slightly due to the scCO2 drying method. The precursor H2PtCl6 could also be impregnated into the MOF pores using a scCO2–ethanol solution. These synthesized samples were reduced by treating in a stream of H2 at 473 K. During the reduction, the formed Pt nanoparticles get dispersed within the MIL-101(Cr). TEM images clearly demonstrate the uniform three-dimensional distribution of Pt nanoparticles in the interior cavities of MIL-101(Cr). The resulting Pt@MIL-101(Cr) composites represent the highly active MOF-immobilized metal nanocrystals for catalytic ammonia borane hydrolysis.
      Graphical abstract image

      PubDate: 2015-12-26T23:28:38Z
       
  • RuCuCo nanoparticles supported on MIL-101 as a novel highly efficient
           catalysts for the hydrolysis of ammonia borane
    • Abstract: Publication date: 1 May 2016
      Source:Microporous and Mesoporous Materials, Volume 225
      Author(s): Kunzhou Yang, Liqun Zhou, Xing Xiong, Menglin Ye, Ling Li, Qinghua Xia
      The catalysts containing Ru, CuCo and trimetallic RuCuCo nanoparticles were successfully synthesized by in-situ reduction of Ru, Cu and Co salts into the highly porous and hydrothermally stable metal–organic framework MIL-101 via a simple liquid impregnation method, and then characterized the structure, size, composition and specific area of the catalysts with different metal nanoparticles loading by XRD, TEM, EDX, ICP-AES, XPS and BET techniques. Their catalytic activities had been examined in ammonia borane hydrolysis to generate hydrogen gas. The result shows that the as-synthesized RuCuCo@MIL-101 exhibits a higher catalytic activity than those of monometallic Ru and bimetallic CuCo counterparts loadings, owing to the strong trimetallic synergistic effects, uniform distribution of nanoparticles as well as bi-functional effects between RuCuCo nanoparticles and the host of MIL-101, with the turn over frequency (TOF) value of 241.2 mol H2 min−1 (mol Ru)−1 and the activation energy (Ea) is determined to be 48 kJ/mol. Moreover, this catalyst exhibits satisfied durability after five cycles for the hydrolytic dehydrogenation of ammonia borane.
      Graphical abstract image

      PubDate: 2015-12-23T11:37:24Z
       
  • Mesoporous silica with block copolymer templates: Modulation of porosity
           via block copolymer reaction with silica
    • Abstract: Publication date: 1 May 2016
      Source:Microporous and Mesoporous Materials, Volume 225
      Author(s): Miaolin Huang, Lei Li, Sixun Zheng
      A polystyrene-block-poly(2-hydroxyethylacrylate) diblock copolymer (PS-b-PHEA) was synthesized via a reversible addition-fragmentation chain transfer (RAFT) polymerization approach. This novel amphiphilic diblock copolymer was successfully used as the template to obtain the mesoporous silica materials. In order to modulate the porosity of mesoporous silica materials, this diblock copolymer was further functionalized via its reaction with 3-isocyanatopropyltriethoxysilane (IPTES) to afford a new diblock copolymer bearing an alkyloxysilane subchain. This derivate diblock copolymer was also employed to prepare the mesoporous silica materials through the inter-component reaction between the block copolymer and silica matrix. The results of small angle X-ray scattering (SAXS), transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET) measurements showed that the inter-component reaction can be utilized to modulate the morphologies and porosity of the mesoporous silica materials.
      Graphical abstract image

      PubDate: 2015-12-23T11:37:24Z
       
 
 
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