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PHYSICS (557 journals)            First | 1 2 3 4 5 6 | Last

Journal of Porphyrins and Phthalocyanines     Hybrid Journal   (Followers: 2)
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Journal of Reinforced Plastics and Composites     Hybrid Journal   (Followers: 5)
Journal of Research in Physics     Open Access  
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Journal of Sensors     Open Access   (Followers: 7)
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Journal of Superconductivity and Novel Magnetism     Partially Free   (Followers: 1)
Journal of Synchrotron Radiation     Hybrid Journal   (Followers: 1)
Journal of Testing and Evaluation     Full-text available via subscription   (Followers: 11)
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Journal of the Brazilian Society of Mechanical Sciences     Open Access   (Followers: 1)
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Journal of the Korean Physical Society     Partially Free   (Followers: 1)
Journal of Theoretical and Applied Physics     Open Access   (Followers: 1)
Journal of Tissue Engineering     Open Access   (Followers: 4)
Journal of Ultrasound in Medicine     Full-text available via subscription   (Followers: 4)
Journal of Vibration and Control     Hybrid Journal   (Followers: 21)
Journal of Visualization     Hybrid Journal   (Followers: 2)
Journal of Zhejiang University SCIENCE A     Hybrid Journal  
Jurnal Penelitian Sains (JPS)     Open Access  
Language Learning Journal     Hybrid Journal   (Followers: 13)
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Latvian Journal of Physics and Technical Sciences     Open Access  
Learning Technologies, IEEE Transactions on     Hybrid Journal   (Followers: 10)
Les Houches Summer School Proceedings     Full-text available via subscription  
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Living Reviews in Solar Physics     Open Access  
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Macalester Journal of Physics and Astronomy     Open Access  
Machining Science and Technology: An International Journal     Hybrid Journal   (Followers: 2)
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Magnetics Letters, IEEE     Hybrid Journal   (Followers: 4)
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Mechanics of Advanced Materials and Structures     Hybrid Journal   (Followers: 3)
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Metamaterials     Hybrid Journal   (Followers: 2)
Micro and Nano Systems Letters     Open Access   (Followers: 4)
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Microporous and Mesoporous Materials     Hybrid Journal   (Followers: 3)
Modern Instrumentation     Open Access   (Followers: 3)
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Molecular Diversity     Hybrid Journal  
Moscow University Physics Bulletin     Hybrid Journal  
Multibody System Dynamics     Hybrid Journal   (Followers: 1)
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Noise & Vibration Worldwide     Full-text available via subscription   (Followers: 5)
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Nondestructive Testing And Evaluation     Hybrid Journal   (Followers: 7)
Nonlinear Dynamics     Hybrid Journal   (Followers: 5)
NTM Zeitschrift für Geschichte der Wissenschaften, Technik und Medizin     Hybrid Journal   (Followers: 4)
Nuclear Engineering and Design     Hybrid Journal   (Followers: 12)
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Nuclear Receptor     Full-text available via subscription   (Followers: 1)
Open Journal of Biophysics     Open Access   (Followers: 1)

  First | 1 2 3 4 5 6 | Last

Journal Cover   Microporous and Mesoporous Materials
  [SJR: 1.306]   [H-I: 93]   [5 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1387-1811
   Published by Elsevier Homepage  [2589 journals]
  • A combined theoretical and experimental analysis on transient
           breakthroughs of C2H6/C2H4 in fixed beds packed with ZIF-7
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): De-Li Chen , Ningwei Wang , Chunhui Xu , Gaomei Tu , Weidong Zhu , Rajamani Krishna
      The selective separation of C2H6/C2H4 mixtures can be achieved by the zeolitic imidazolate framework ZIF-7, which is a well-known flexible microporous material due to its gate-opening effect in response to external stimuli such as pressure and temperature. Transient breakthrough experiments with C2H6/C2H4 mixtures were carried out at varying pressure and temperature conditions to confirm the potential application of ZIF-7 to selectively adsorb the saturated alkane and reject the unsaturated alkene in the gas phase during the adsorption cycle. Transient breakthrough simulations, including the influence of intra-crystalline diffusion, were compared with the experimental breakthroughs. The assumption of negligible diffusional limitations is able to capture the essential characteristics of the experimental breakthroughs. With the breakthroughs from both experiments and simulations, the adsorbed amounts of C2H6 and C2H4 in ZIF-7 were calculated to estimate the separation selectivity, which is in reasonable agreement with ideal adsorbed solution theory calculations. The derived isosteric heats of adsorption for both adsorbates are compared and used to explain the adsorption selectivity for C2H6 over C2H4 in ZIF-7. The good agreement between experiments and simulations verifies that the simulation methodology employed in the current study is a valuable and efficient tool for modeling the separation performance of C2H6/C2H4 mixtures in ZIF-7.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • ZSM-5 and ferrierite synthesized by magadiite conversion method in 1,
           6-hexamethylenediamine system
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Yu Wang , Tianming Lv , Huilong Wang , Yalei Zhao , Changgong Meng , Hao Liu
      ZSM-5 and ferrierite have been successfully synthesized by magadiite conversion method using 1, 6-hexamethylenediamine (HMD) as structure directing agent. The binary crystallization phase diagram was obtained by various reactant ratios of H2O/SiO2 and SiO2/Al2O3 and the regular phase transformations were also demonstrated. The optimized reactant HMD/SiO2 ratio was 0.6. The high crystalline ZSM-5 was composed of coffin-shaped crystallite with length of 4 μm where as ferrierite exhibited plate-like crystallite having a diameter of 8 μm. The 13C MAS NMR spectra revealed that the HMD which can be used as a structure directing agent in the conversion process was held tenaciously inside the pores of ZSM-5 and ferrierite. The formula of as-obtained ZSM-5 and ferrierite could be K2.1(C6H16N2)4.2(H2O)16.9H8.4 [Si85.5Al10.5O192] and K2.1(C6H16N2)0.9(H2O)6.4H2.2 [Si31.7Al4.3O72] respectively based on the compositional analysis. More over the structure of prepared ZSM-5 and ferrierite were collapsed when the temperature rose up to 1200 °C and 1100 °C respectively; both are exceptionally stable towards strong acid.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • Prediction of gas storage capacities in metal organic frameworks using
           artificial neural network
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Zeynep Yıldız , Harun Uzun
      In this study, artificial neural network was developed to forecast adsorption capacity of hydrogen gas in metal organic frameworks. Surface area, adsorption enthalpy, temperature and pressure were selected as input parameters. Hydrogen storage capacities of MOFs were computed using these four parameters. An artificial neural network was used to model the adsorption process. The prediction results were remarkably agreed with the experimental data.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • Thermal transformation of Cs-clinoptilolite to CsAlSi5O12
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Antonio Brundu , Guido Cerri
      In this study we have investigated the protocol to produce CsAlSi5O12 (CAS), a potential host for radioactive cesium, starting from clinoptilolite, a natural zeolite employed in cesium decontamination. A clinoptilolite-rich rock sampled in Sardinia (Italy) has been subjected to a beneficiation process, to obtain a powder with a higher zeolite content. The enriched material (90 wt% clinoptilolite) has been previously Na-, then Cs-exchanged. Both forms have been analyzed by ICP-AES and ICP-MS. Thermal treatments of 2 hours between 800 and 1250 °C have been performed on different aliquots of the Cs-exchanged material. Samples heated at T ≥ 1150 °C are composed basically only by CAS, as determined by XRD analyses, and their high crystallinity has been also confirmed by SEM observations. Ideally, the nucleation of CAS follows the reaction Cs6Al6Si30O72·nH2O → nH2O↑ + 6CsAlSi5O12. DTA analyses indicate that the transformation has occurred at 1145 °C. TG analyses, coupled with XRD data, lead to exclude a cesium volatilization during the synthesis of CAS.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • Calculation of microchannel parameters in aluminophosphate zeolites
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): I.V. Grenev , V.Yu. Gavrilov
      Adsorption interaction of molecular hydrogen with framework atoms of aluminophosphate zeolites AlPO-5, -11, -8 and -36 were analyzed using a representative fragment of the structure with the volume about 32 nm3. Isopotential surfaces of the interaction between molecules were calculated. Isopotential surfaces with zero adsorption potential outline the shape of microchannels. Theoretical values of the zeolite microchannel volumes were calculated. Places for preferential localization of the sorbate molecules in the zeolite structure (places with the lowest adsorption potential) were determined for the Henry adsorption isotherm range. Calculated and experimental values of Henry constants for hydrogen adsorption at 77 K were compared.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • Stability of UiO-66 under acidic treatment: Opportunities and limitations
           for post-synthetic modifications
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): C.G. Piscopo , A. Polyzoidis , M. Schwarzer , S. Loebbecke
      In chemical and functional modification of Metal-organic frameworks (MOFs), preserving their structure and topology is a challenging goal, due to the high sensitivity of these materials to moisture, chemical and thermal treatments. The porous material UiO-66 is one of the most stable MOFs, retaining its properties under a relative wide range of chemical and physical conditions. The unique robustness of UiO-66 derives from the 12-coordinated Zr6-clusters that constitute the framework. Nevertheless, variation on the synthetic pathways may lead to different coordination of the Zirconium sites, influencing the stability and activity of this MOF during applications such as catalysis. Herein a survey of the stability of UiO-66 under acidic treatment is presented. The porous metal-organic framework has been synthesized according to two alternative procedures; these two solid materials and a commercially available UiO-66 sample have been suspended in several aqueous acids and have been characterized after the impregnation tests. These results lead to a better understanding of the matter of acidic stability of the selected MOF, clarifying whether it is possible to enhance its stability by choosing a dedicated synthesis route and providing essential information in order to proceed with a large number of post-synthetic modifications. Among these reactions, the sulfonation of UiO-66, which is an example of outstanding importance, has been investigated. The stability of UiO-66 versus mineral acids has been confirmed; however this MOF does not tolerate the use of electrophilic cationic species.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • Promotion of phosphoester hydrolysis by the ZrIV-based metal-organic
           framework UiO-67
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Patrique Nunes , Ana C. Gomes , Martyn Pillinger , Isabel S. Gonçalves , Marta Abrantes
      The ZrIV-based metal-organic framework (MOF) UiO-67 has been examined as a promoter of the hydrolysis of phosphoester bonds by using sodium para-nitrophenylphosphate (pNPP) as a model substrate. The reactions were followed by 1H NMR spectroscopy and performed under mild conditions using 2–100 mol% of the MOF relative to pNPP. All of the systems studied promoted the hydrolysis of pNPP to give para-nitrophenol (pNPh) and inorganic phosphate. A reaction half-life of ca. 30min was achieved using 17 mol% of UiO-67 at 55 °C and 30 mol% at ambient temperature; ≥98% removal of pNPP was reached within 1 h for both reaction temperatures. 1H NMR spectra of the reaction solutions, together with powder X-ray diffraction, FT-IR spectroscopy and solid-state NMR data for the recovered MOF, revealed that (i) pNPP was encapsulated and then converted to pNPh within the cavities of UiO-67, (ii) both pNPh and inorganic phosphate were retained in the solid promoter, and (iii) the MOF suffered partial structural breakdown into the components Zr6O4(OH)4 and 4,4′-biphenyldicarboxylate, with partial release of the latter into solution. These structural changes eventually compromized the recyclability of the promoter, although the material could be recovered and reused in a second cycle without loss of activity.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • Multi-scale characterization of porosity in Boom Clay (HADES-level, Mol,
           Belgium) using a combination of X-ray μ-CT, 2D BIB-SEM and FIB-SEM
           tomography
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Susanne Hemes , Guillaume Desbois , Janos L. Urai , Birgit Schröppel , Jens-Oliver Schwarz
      The Oligocene age Boom Clay is a potential host material for radioactive waste disposal in Belgium. To better understand the physical basis of transport mechanisms of radionuclides, we aim to characterize the pore space and its connectivity at nm-scale in 3D. In the present study, X-ray μ-CT and FIB-SEM (focused ion beam scanning electron microscopy) tomography were combined, to investigate the 3D pore space of a Boom Clay sample from the Mol-1 borehole (depth corresponding to the level of the HADES-URF – ‘high activity disposal experimental site underground research facility’) at the Mol–Dessel research site for radioactive waste disposal (Belgium). BIB-SEM (broad ion beam scanning electron microscopy) was used to bridge the gap in resolutions between X-ray μ-CT and FIB-SEM and to optimize the selection of a relevant spot for FIB-SEM. Pore network extraction (PNE) modeling (Dong and Blunt, 2009 [1]) was used to simplify the results into a set of pore bodies and pore throats, which are suitable for a statistical description. Resulting pore-size distributions are interpreted to be power-law distributed over ∼6 orders of magnitude, showing the scale-invariance of the pore space. We present a conceptual model of the 3D pore network in Boom Clay. The extracted 3D pore network model can be used to estimate transport properties – in digital rock models.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • Porous graphitic carbon materials prepared from cornstarch with the
           assistance of microwave irradiation
    • Abstract: Publication date: 1 July 2015
      Source:Microporous and Mesoporous Materials, Volume 210
      Author(s): Hong Lei , Yuhao Wang , Jichuan Huo
      Porous graphitic carbon materials (PGCs) have attracted great interest because of their properties shown in fields such as catalyst supports, electrochemical double layer capacitors, Li-ion batteries, etc. Biomass is a promising resource to produce PGCs, as it is cheap, eco-friendly and renewable. Using cornstarch as raw material, two PGCs (PGC-1 and PGC-2) were prepared by combining microwave-assisted catalytic graphitization and chemical activation. PGC-1 was made from new gelatinized starch and the other (PGC-2) from retrograded starch. The former was mainly composed of graphitic nanocoils. The latter, on the other hand, was more likely to be a product of activated loose packing carbonaceous sheets. Narrowly distributed hierarchical pores were observed in the PGCs. Both of the PGCs were partly graphitized and had large surface areas (353 m2/g for PGC-1 and 686 m2/g for PCG-2). Cyclic voltammetry and electrochemical impedance spectroscopy test showed that they had good capacitive property.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • CO2 sorption onto silica mesoporous materials made from nonionic
           surfactants
    • Abstract: Publication date: 1 July 2015
      Source:Microporous and Mesoporous Materials, Volume 210
      Author(s): Nabila Chalal , Hasna Bouhali , Hadj Hamaizi , Bénédicte Lebeau , Abdelkader Bengueddach
      Spherical mesoporous silica particles were successfully prepared by using non-ionic amphiphilic di-block co-polymers CnH2n+1-(EO)x-OH as templates and tetraethylorthosilicate (TEOS) as silica precursor. The synthesized mesoporous silica materials were characterized by X-ray diffraction (XRD), N2 adsorption–desorption and scanning electron microscopy (SEM) techniques. CO2 adsorption at 273 K was evaluated by a volumetric method, and the CO2 sorption behavior was described by applying both Langmuir and Freundlich equations. Results indicate a high adsorption capacity of CO2 (5–9 mmol/g), depending essentially on the porous texture of the materials. An adsorption kinetic model was used to describe the adsorption of CO2 over template-free mesoporous siliceous materials. A good agreement with experimental data was found.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • Preparation of hierarchical porous biomorphic carbide-derived carbon by
           polycarbosilane impregnation of wood
    • Abstract: Publication date: 1 July 2015
      Source:Microporous and Mesoporous Materials, Volume 210
      Author(s): Marion Adam , Martin Oschatz , Winfried Nickel , Stefan Kaskel
      Biomorphic carbide-derived carbon (CDC) materials with hierarchical pore structure are prepared by polycarbosilane impregnation of carbonized wood monoliths followed by subsequent pyrolysis and high-temperature chlorine treatment. Hierarchical pore structures are generated with combined macropores from the original cell structure of the wood and micro-/mesopores, investigated by scattering electron microscopy and nitrogen physisorption, respectively. The influence of polycarbosilane solutions concentration (20–100 wt.%), impregnation time (12–96h), and impregnation cycle number (1–3 times) on the mass gain during impregnation as well as specific surface area and nanopore volume of resulting CDCs is studied. Increasing concentration, time, and number of impregnation cycles lead to higher amount of infiltrated polymer in the wood monolith resulting in higher specific surface areas up to 940m2/g for the resulting CDCs. A linear increase of specific surface area as well as micro- and total pore volume with increasing mass gain takes place for all samples, independent of the impregnation conditions.
      Graphical abstract image

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

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

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

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

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

      PubDate: 2015-02-28T16:41:24Z
       
  • Simplified preparation of SnO2 inverse opal for Methanol gas sensing
           performance
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Jinquan Wang , Yanmei Xu , Weichao Xu , Ming Zhang , Xiaobing Chen
      As a novel structure, inverse opal, with three dimensional periodic macropore and mesopore, huge specific surface area, is promising in highly sensitive gas sensing. In this paper, SnO2 inverse opal was prepared with a simplified polystyrene (PS) opal template cooperating with sol–gel method. The simplified method could spare much work and avoid the operation of the SnO2 inverse opal scraped from microslide. The performance of the SnO2 inverse opal sensor to methanol gas was systemically investigated. The results indicate that the sensing performance of the SnO2 inverse opal sensor to methanol gas is highly improved than traditional sensors. The response of the SnO2 inverse opal sensor is as high as 95 for 500 ppm methanol gas detection. In the range from 1 to 1000 ppm, the SnO2 inverse opal sensor shows fine linear relationship with the growth of the methanol gas concentrations.
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      PubDate: 2015-02-28T16:41:24Z
       
  • Synthesis of mesoporous graphitic C3N4 using cross-linked bimodal
           mesoporous SBA-15 as a hard template
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Hui-Min Zhao , Chang-Miao Di , Lan Wang , Yuan Chun , Qin-Hua Xu
      Mesoporous graphitic C3N4 has been synthesized using a novel cross-linked bimodal mesoporous (CLBM) SBA-15 as a hard template. This cross-linked bimodal mesoporous SBA-15 template was prepared by adjusting the pH to alter the copolymer micelle size. The resulting mesoporous g-C3N4 replicates the morphology of the mesoporous silica template, and numerous pore openings are formed on the surfaces. The mesoporous g-C3N4 exhibits a high specific surface area and a large pore volume. The photocatalytic degradation activity of methyl orange on mesoporous g-C3N4 is nearly 15.3 times as high as that on bulk-g-C3N4 under visible light irradiation. The high photocatalytic performance of this sample is due to the high specific surface area and more readily accessible active sites.
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      PubDate: 2015-02-28T16:41:24Z
       
  • Molecular engineering of microporous crystals: (VIII) The
           solvent-dependence of the structure-directing effect of ethylenediamine in
           the synthesis of open-framework aluminophosphates
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Huiying Lu , Jun Xu , Pan Gao , Wenfu Yan , Feng Deng , Ruren Xu
      By heating two mixtures with the molar composition of Al2O3:3.0 P2O5:4.0 ethylenediamine (en):90 ethylene glycol (EG):7.9 H2O and Al2O3:3.0 P2O5:4.0 ethylenediamine (en):90H2O at 180 °C, one-dimensional (1D) chain-like aluminophosphate 1 ([AlP2O8H][N2C2H10]) and three-dimensional (3D) open-framework aluminophosphate AlPO4-12 ([Al3P3O13][N2C2H10]) were obtained, respectively. The crystallization processes were investigated using powder X-ray diffraction (XRD) and solid-state magic-angle spinning nuclear magnetic resonance (MAS NMR) techniques. The evolution of the coordination state of Al and P during the crystallization was monitored. A possible starting point (core unit) for the crystallization of both structures was suggested. The correlation between the core units and the long-range ordering of the planes first appeared in the early stage of both crystallization processes were investigated. The results show that the solvent can affect the structure-directing effect of ethylenediamine by altering the type and distribution of the fragments formed in the synthetic system and the starting point (core unit) of the crystallization, which will determine the structure of the resulting crystals. The long-range ordering along the direction that is represented by the diffraction peaks which appeared earlier than other diffraction peaks during the crystallization process might be formed from a core unit.
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      PubDate: 2015-02-28T16:41:24Z
       
  • Conjugated polymer and spirolactam rhodamine-B derivative
           co-functionalized mesoporous silica nanoparticles as the scaffold for the
           FRET-based ratiometric sensing of mercury (II) ions
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Lijuan Feng , Jie Sha , Yao He , Shaopeng Chen , Bingxin Liu , Haixia Zhang , Changli Lü
      A novel fluorescence resonance energy transfer (FRET)-based ratiometric nanosensor is reported for toxic Hg2+ ions detection. Poly(p-phenylenevinylene) (PPV) chain was encapsulated into the pores of mesoporous silica nanoparticles (MSNs) by ion-exchange and in situ polymerization, and used as the energy-transfer donor. A spirolactam rhodamine-B derivative (SRhB), as an ion recognition element and energy-transfer acceptor, was embedded in the pores of MSNs to form PPV@MSN@SRhB as the nanosensor. The presence of Hg2+ in the dispersion solution of nanoparticles can induce the ring-opening reaction of the SRhB moieties and lead to the occurrence of FRET process, affording the nanoparticle system a ratiometric sensor for Hg2+ ions. The nanoparticle sensor can selectively detect Hg2+ ions with a detection limit of 200 nM (ca. 40 ppb). It has been found that the fabricated FRET-based scaffold with the conjugated polymer as a donor exhibited high environmental stability and was more preferred for the accurate ratiometric sensing. Moreover, the FRET-based ratiometric nanosensor can be applicable in a relatively wide pH range (pH = 5–8) in solution.
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      PubDate: 2015-02-28T16:41:24Z
       
  • Mesoporous alumina infiltrated with a very thin and complete carbon layer
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Galina N. Ilinich , Ren I. Kvon , Artem B. Ayupov , Victor A. Chumachenko , Anatoly V. Romanenko
      The mesoporous composite material “carbon-infiltrated alumina” was synthesized via chemical vapor infiltration of pyrocarbon in a porous alumina (γ-Al2O3) matrix. The process was carried out under continuous flow conditions at 650–800 °C and 1 bar of the reaction gas mixture containing ethylene (5 or 15 vol. %) and Ar (balance). A number of the synthesis parameters were examined to determine the conditions that are necessary for the formation of a thin but complete carbon layer over the alumina surface. A special acquisition mode of X-ray photoelectron spectroscopy was suggested and validated for the fast and reliable testing of completeness and uniformity of the carbon deposits on the outer alumina surface. Low-temperature N2 adsorption and electron microscopy were used to study the porous structure of γ-Al2O3 after high-temperature pretreatments and the carbon-infiltrated materials as well as the same samples after treatment with an aqueous hydrochloric acid solution. As a result of these studies, the mesoporous carbon-infiltrated aluminas with an extremely thin (1–1.5 carbon layers) and complete carbon coating, high electrical conductivity and excellent endurance in acidic medium have been prepared.
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      PubDate: 2015-02-28T16:41:24Z
       
  • The effect of pore structure on the CO2 adsorption efficiency
           of polyamine impregnated porous carbons
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): J.A. Arran Gibson , Andrei V. Gromov , Stefano Brandani , Eleanor E.B. Campbell
      The effect of polyamine impregnation on the CO2 adsorption properties of two different porous carbons, one microporous and one mesoporous, was studied systematically. The pore filling during impregnation with polyamines was shown to result in a fraction of the unfilled micropore volume being blocked for gas adsorption. Thermal gravimetric analysis was used to compare the CO2 capacity at 0.1 bar with respect to the carbon support type, the amount of amine loading, and the type of amine. A 12 fold increase in the CO2 capacity was observed when the impregnated activated carbon was compared to the raw starting material. A heat of adsorption for amine impregnated support of ∼90 kJ mol−1 was found, clearly indicating a chemisorption mechanism. The mesoporous material provided a more efficient support for the amine to interact with the CO2. The interaction between low molecular weight amines and CO2 showed a more efficient utilization of the basic groups in comparison to high molecular weight species.
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      PubDate: 2015-02-28T16:41:24Z
       
  • Tunable hierarchical porous silica materials using hydrothermal
           sedimentation-aggregation technique
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Abdelali Zaki , Jing Xu , Gregory Stoclet , Sandra Casale , Jean-Philippe Dacquin , Pascal Granger
      Herein, a simple and efficient synthesis based on a dual templating approach allow the preparation of tunable macroporous mesoporous silica materials. Macropores incorporation has been obtained using polymer spheres of well-defined size and their subsequent removal by thermal treatment allowed the independent control of the macropore size entrance between 200 nm and 50 nm. The addition of the block copolymer drives the formation of a second mesostructured skeleton, with a pore size centered around 4 nm, throughout the material framework. By a fine tuning of the sol–gel synthesis parameters (Polymer:TEOS ratio, aging conditions), we succeeded in guiding the SBA-15 rod-like morphology having randomly packed macropores to a derived SBA-15 with a homogeneous honeycomb macrostructure. Moreover, large mesoporous windows are generated between adjacent macropores. Hence, this simple one-pot synthesis approach, allowing scaling-up, offers fine tuning porosity at the macropore scale.
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      PubDate: 2015-02-28T16:41:24Z
       
  • Bulk hierarchical nanoporous palladium prepared by dealloying PdAl alloys
           and its electrochemical properties
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Qingquan Kong , Lixian Lian , Ying Liu , Jing Zhang , Li Wang , Wei Feng
      Bulk hierarchical nanoporous palladium (BHNPP) materials composing both bimodal porous structure and monolithic porous structure were fabricated by chemical dealloying of Pd20Al80 alloy with sub-micrometer grain size via mechanical alloying and spark plasma sintering process (MA-SPS). The different nanoporous structures were formed in the regions where the microstructure was heterogeneous. Monolithic porous structure were formed after dealloyed of monolithic grain structure mainly composed of PdAl3 phase, and bimodal porous structure with both larger pore of hundreds nanometers and smaller pore of a few nanometers were obtained after dealloyed of nanocrystalline structure consist of PdAl3 and Al phases, respectively. Effects of dealloying time, concentration of dealloying solutions and chloride ion (Cl−) on the evolution of the microstructure of BHNPP were also studied. Ligament of BHNPP can be facility coarsen by add chloride rather than only raise the concentration of HCl solution. Moreover, the cyclic voltammetry results reveal that the BHNPP materials have superior ethanol oxidation ability.
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      PubDate: 2015-02-28T16:41:24Z
       
  • Separation of alcohol/water mixtures by ZSM-5 bulk bodies prepared with a
           one-pot hydrothermal method
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Eisaku Igi , Yoshikazu Kameshima , Shunsuke Nishimoto , Michihiro Miyake
      The present work demonstrates a novel separation technique by ZSM-5 zeolite bulk bodies, which were successfully prepared with a one-pot hydrothermal method at 200 °C for 5 d, using the raw materials that are used in the synthesis of ZSM-5 powders. It is found that these materials can efficiently concentrate a 5 mass% ethanol/water mixture by vapor permeation at approximately 5 kPa to produce a permeate of approximately 76 mass% at an extremely large flux of about 35 kg·(m2 h)−1, even though they are porous. The permeate flux is unchanged for a long time. These bulk bodies show promise as materials for the innovative energy-efficient separation of ethanol/water, especially compared with the membranes previously used for such separations. Furthermore, they can efficiently concentrate 5 mass% methanol/water and 2-propanol/water mixtures.
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      PubDate: 2015-02-28T16:41:24Z
       
  • Highly conductive titanium oxide nanotubes chemical sensors
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): E. Comini , V. Galstyan , G. Faglia , E. Bontempi , G. Sberveglieri
      Nb–TiO2 nanotubes arrays have been prepared by anodisation of Nb–Ti metallic films. After the annealing treatment the nanotubes are crystallized in the anatase phase. Conductance increased of several orders of magnitude thanks to the introduction of Nb. We have prepared conductometric sensors and evaluated their sensing properties towards different gases. Functional measurements demonstrated very good sensing performances towards ethanol, acetone and carbon monoxide. The gas sensing performances has been tested as a function of the dimensions of the nanotubes showing an improvement in chemical sensing as the internal diameter of the tubes get smaller.
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      PubDate: 2015-02-28T16:41:24Z
       
  • De- and re-hydration of scolecite revisited: An in situ single-crystal
           X-ray study under low and high humidity conditions
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Georgia Cametti , Rosa Micaela Danisi , Thomas Armbruster , Mariko Nagashima
      Dehydration dynamics and thermal stability of scolecite CaAl2Si3O10·3H2O, Z = 8 (NAT framework type) has been investigated between 25 and 300 °C by in situ single-crystal X-ray diffraction at 30(5) % RH (high P H2O) and under dry nitrogen conditions (low P H2O). The dehydration under high P H2O can be described as a two-step process: scolecite (3H2O) – metascolecite (2H2O) – X-ray amorphous anhydrous phase. At 150 °C, below the transformation from scolecite to metascolecite, a new triclinic intermediate structure was analyzed. This transformation represents a transitory stage between scolecite and metascolecite in terms of the Ca and H2O distribution. For the first time hydrogen positions have been located for metascolecite (220 °C) quenched to −100 °C, enabling evaluation of the hydrogen bond system. The second set of experiments, carried out under low P H2O, led to the temperature-dependent phase sequence: scolecite – metascolecite – x2-phase – x1-phase – amorphization. The x2-phase has CaAl2Si3O10·½H2O composition (space group Ad11, Z = 8, a = 17.536(4), b = 17.493(5), c = 6.4847(15) Å, α = 88.884(17)°. The x1-phase is anhydrous CaAl2Si3O10 (space group Fd11, Z = 8, a = 16.327(8), b = 17.433(8), c = 6.521(3) Å, α = 85.69(3)°). Both structures represent strongly compacted and distorted varieties of the NAT framework type. The volume change from scolecite to metascolecite, x2-phase, and x1-phase amounts to −2, −11, and −7%, respectively. Metascolecite (200 °C, high P H2O) was rehydrated under ambient conditions to scolecite. The resulting rehydrated structure (3H2O) is different to original scolecite and shows significant Ca disorder corresponding to the intermediate structure at 150 °C.
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      PubDate: 2015-02-28T16:41:24Z
       
  • Synthesis, characterization and catalytic performance of well-ordered
           mesoporous Ni-MCM-41 with high nickel content
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Jing Qin , Baoshan Li , Wen Zhang , Wei Lv , Chunying Han , Jianjun Liu
      The well-ordered Ni-MCM-41 with high nickel content was synthesized by a direct hydrothermal method using cetyltrimethylammonia bromide as the structure-directing agent in an ammonia aqueous solution. The resulting samples were characterized by X-ray diffraction, X-ray fluorescence spectroscopy, high-resolution transmission electron microscopy, nitrogen adsorption–desorption isotherms, H2 temperature-programmed reduction analyses, Fourier-transform infrared spectroscopy, ammonia temperature programmed desorption, and X-ray photoelectron spectroscopy. The results indicated that the material maintained ordered physical mesostructure of MCM-41 with high nickel content, and the nickel atoms were mainly in the framework with tetrahedral coordination. The materials possessed high specific surface area (800–580 m2 g−1), large total pore volume (1.05–1.22 cm3 g−1) and pore diameter (2.77–3.16 nm). The material exhibited excellent catalytic performance for the hydrocracking of coker wax oil, which was improved with the increasing of Ni content in the framework of the molecular sieves.
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      PubDate: 2015-02-28T16:41:24Z
       
  • Structure, topology and property of metal-organic frameworks with
           pyridine-3,5-bis(phenyl-4-carboxylate) and varied metal centers
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Pei-Pei Cui , Xiu-Du Zhang , Yue Zhao , Kai Chen , Peng Wang , Wei-Yin Sun
      Four new metal-organic frameworks {[Zn(L)]·2.6H2O}n (1), [Cd(L)(H2O)(DMA)]n (2), [Co3(L)2(HCOO)2(H2O)2]n (3) and {[Mn(L)(H2O)]·DMF}n (4) [H2L = pyridine-3, 5-bis(phenyl-4-carboxylic acid), DMA = N,N-dimethylacetamide, DMF = N,N-dimethylformamide] have been synthesized and characterized by single crystal and powder X-ray diffractions, IR and thermogravimetric analyses. 1 is a three-dimensional (3D) framework with {46·64} topology, while 2 is a 3D framework formed by parallel/parallel inclined interpenetration of two-dimensional (2D) networks with {63} topology. 3 processes a 3D framework structure with point symbol of {4·82}2{42·812·10}, and 4 shows bilayer structure with {43·63} topology, which is further assembled into a 3D supramolecular architecture by hydrogen bonding interactions. Gas adsorption property of 1, 2 and 4, photoluminescence of 1 and 2 as well as magnetic property of 4 were investigated.
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      PubDate: 2015-02-28T16:41:24Z
       
  • Structuring zeolite bodies for enhanced heat-transfer properties
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Lars Borchardt , Nina-Luisa Michels , Torsten Nowak , Sharon Mitchell , Javier Pérez-Ramírez
      The predominantly insulating nature of zeolites, as many classes of porous catalysts, can severely impair heat transfer and hence their performance in industrial processes. Strategies developed to engineer the thermophysical properties of technical zeolites for fixed-bed applications comprise the use of conductive secondary phases as structured catalyst supports or as inert diluents. However, the impact of integrating conductive additives into composite zeolite bodies (pellets, extrudates, or granules) has not been widely explored. Here, using a transient hot-plate technique to decouple the distinct contributions of porosity, sample hydration, and temperature, we quantify the impact of metallic (copper), ceramic (silicon carbide, aluminum nitride, boron nitride), and carbonaceous (graphite, carbon nanotubes) phases on the thermal conductivity of shaped zeolites at the body and packed-bed scales. The decisive role of particle morphology, dominating over the intrinsic conductivity of an additive, is corroborated through the three-dimensional reconstruction of data acquired by focused ion beam-scanning electron microscopy and X-ray microtomography coupled with in-situ thermographic studies. In particular, the order-of-magnitude improvement evidenced on application of graphite sheets stems from the extended paths of low thermal resistance created in the millimeter-sized catalyst ensemble. Through the identification of structure-property relations, our approach provides new insights into the rational design of composite porous materials with enhanced heat-transfer properties.
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      PubDate: 2015-02-28T16:41:24Z
       
  • Triptycene structure-directing agents in aluminophosphate synthesis
    • Abstract: Publication date: 15 May 2015
      Source:Microporous and Mesoporous Materials, Volume 208
      Author(s): Ben W. Boal , Stacey I. Zones , Mark E. Davis
      The synthesis of aluminophosphates is investigated using a number of triptycene-based organic structure-directing agents (OSDA). These OSDAs are designed to synthesize extra-large pore and/or large cavity-containing molecular sieves. Starting from the hydrophobic triptycene molecule, OSDAs are prepared by introducing three amine-based centers that can be charged either by protonation in the acidic aluminophosphate reaction media or through quaternization. VPI-5 is synthesized using these tripytycene OSDAs, and the OSDAs are occluded inside the pores. This synthesis marks the first time VPI-5 has been made as a single phase with an OSDA occluded inside the framework of the as-made material that is not removed by simple washing with water or other solvents. Additionally, several other aluminophosphates with unknown structures are synthesized using these new OSDAs.
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      PubDate: 2015-02-28T16:41:24Z
       
  • Editorial Board
    • Abstract: Publication date: 1 May 2015
      Source:Microporous and Mesoporous Materials, Volume 207




      PubDate: 2015-02-28T16:41:24Z
       
  • Vanadium dispersion and catalytic activity of Pd/VOx/SBA-15 catalysts in
           the Wacker oxidation of ethylene
    • Abstract: Publication date: 1 May 2015
      Source:Microporous and Mesoporous Materials, Volume 207
      Author(s): Róbert Barthos , András Hegyessy , Szilvia Klébert , József Valyon
      Transmission electron microscopy (TEM), X-ray diffractometry (XRD), in situ diffuse reflectance ultra violet – visible (UV–Vis) spectroscopy, and temperature-programmed reduction by hydrogen (H2-TPR) were used to identify the vanadia forms in vanadium-containing SBA-15 preparations (VOx/SBA-15). Wacker type supported Pd/VOx/SBA-15 catalysts were obtained by introducing Pd into VOx/SBA-15 samples using conventional impregnation method. The activity of the catalysts was tested in the gas phase partial oxidation of ethylene by O2 in the presence of H2O (Wacker oxidation). VOx/SBA-15 sample was obtained by micelle-templated synthesis using vanadium-containing synthesis gel. The vanadium became incorporated in the silica structure from the gel in near to atomic dispersion. This catalyst was quite active in ethylene oxidation to CO2 but had low Wacker activity. Isolated, polymeric and bulk vanadia species were identified in the VOx/SBA-15 prepared by wet impregnation/calcination method. The specific surface area of the sample was found to be smaller than that of the neat SBA-15 support because some pores were blocked by vanadia agglomerates. The corresponding Pd/VOx/SBA-15 catalyst showed high selectivity for acetaldehyde formation but the activity was relatively low due to low accessible active surface. A third VOx/SBA-15 sample was obtained by applying directed surface reaction between silanol groups of dehydrated SBA-15 and anhydrous solution of vanadyl acetylacetonate. Large number of accessible Pd/VOx sites were present in the corresponding Pd/VOx/SBA-15 catalyst. Latter catalyst induced ethylene oxidation to acetaldehyde with high yield at temperatures ≤160 °C and with good yield to acetic acid at temperatures ≥160 °C.
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      PubDate: 2015-02-28T16:41:24Z
       
  • Development of desilicated EU-1 zeolite and its application in
           conversion of dimethyl ether to olefins
    • Abstract: Publication date: 1 May 2015
      Source:Microporous and Mesoporous Materials, Volume 207
      Author(s): Mohamed H.M. Ahmed , Oki Muraza , Adnan M. Al Amer , Yusuke Sugiura , Norikazu Nishiyama
      Creating mesoporosity in one-dimensional pore zeolites is still a challenging task in zeolite scientific community. Desilicated EU-1 (EUO), an one-dimensional pore zeolite, with Si/Al of 25 was developed using with different NaOH concentrations for different times to extract Si atoms from the framework and to form mesoporosity at fixed treatment temperature. Simple hexamethonium bromide was used as a template for EU-1 synthesis. The effects of concentration of NaOH and time of desilication on Si/Al, crystallinity, acidity and surface area have been investigated. A series of treated EU-1 samples was then applied for conversion of dimethyl ether to olefins (DTO). The sample treated with lower NaOH concentration (0.25 M) had the highest increase in mesopore volume with no significant change in acidity. An increase in mesopore volume contributed to higher selectivity toward propylene. The lower catalytic activity was observed over desilicated EU-1 as compared with the parent sample. The physicochemical properties of desilicated zeolites were analyzed using many characterization techniques. X-ray diffraction (XRD) was used to evaluate the effect of desilication on the crystallinity. Nitrogen adsorption–desorption isotherms and temperature-programmed desorption were used to evaluate the porosity and acidity, respectively. Morphology was analyzed using scanning electron microscope (SEM) and Transmission electron microscope (TEM).
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      PubDate: 2015-02-28T16:41:24Z
       
  • A new method for the synthesis of monodisperse-porous titania microbeads
           by using polymethacrylate microbeads as template
    • Abstract: Publication date: 1 May 2015
      Source:Microporous and Mesoporous Materials, Volume 207
      Author(s): Kadriye Özlem Hamaloğlu , Bekir Çelebi , Ebru Sağ , Ali Tuncel
      Monodisperse-porous titania microbeads were synthesized by sol–gel templating method by using a new type of polymethacrylate microbeads as template. Monodisperse-porous poly(3-chloro-2-hydroxypropyl methacrylate-co-ethylene dimethacrylate), poly(HPMA-Cl-co-EDMA) microbeads 5.4 μm in size were used as starting material for the preparation of new template. Strong cation exchanger –SO3Na groups were generated on the selected polymethacrylate template via the reaction between chloropropyl groups of template and sodium bisulfite. –SO3Na functionalized-polymethacrylate microbeads were treated with the precursor, TiCl4 in an aqueous medium and subsequently treated with ammonia to obtain titania-polymer composite microbeads. The composite microbeads were then calcined at 450 °C to have monodisperse-porous titania microbeads. Monodisperse-porous titania microbeads in the size range of 3.0–5.0 μm with crater-like or fine porous structures with specific surface areas ranging between 50 and 91 m2/g were obtained by changing the concentration, crosslinking density of the template beads and the calcination temperature. The selection of a polymethacrylate template decomposed at lower temperatures with respect to poly(styrene-co-divinylbenzene) type templates, commonly used for synthesis of porous titania microbeads, allowed to perform the calcination of titania-polymer composite microbeads at lower temperatures. Monodisperse-porous titania microbeads with higher specific surface area and a crystalline structure with higher percent of anatase phase could be obtained by performing calcination at lower temperatures. The photocatalytic activity of monodisperse-porous titania microbeads was investigated using an anionic azo-dye, Remazol Black 5 (RB5) in batch-fashion. Higher photodegradation rates were observed with the monodisperse-porous titania microbeads in the acidic pH region compared to TiO2 nanoparticles.
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      PubDate: 2015-02-28T16:41:24Z
       
  • Alkylation of phenol with tert-butyl alcohol over dealuminated HMCM-68
           zeolites
    • Abstract: Publication date: 1 May 2015
      Source:Microporous and Mesoporous Materials, Volume 207
      Author(s): Jintao Li , Lan-Lan Lou , Yajing Yang , He Hao , Shuangxi Liu
      A series of dealuminated HMCM-68 zeolites were prepared by treatment with steaming or hydrochloric/citric acid leaching. Their catalytic properties were studied using the alkylation of phenol with tert-butyl alcohol as a test reaction. The HMCM-68 zeolite modified by citric acid for 8 h (CAZ8) showed the best catalytic performance due to its improved structural and acidic properties, confirmed by methods of XRD, ICP-AES, SEM, N2-adsorption, 27Al MAS NMR and NH3-TPD. Furthermore, it is proposed that citric acid treatment is the most suitable method for dealumination of HMCM-68 zeolite in the alkylation of phenol, which results in the zeolites having improved adsorption polarity, as well as enlarged surface area and pore volume for the desired transformation. The factors affecting the reaction over CAZ8 have also been extensively investigated.
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      PubDate: 2015-02-28T16:41:24Z
       
  • Hydrophilic SOD and LTA membranes for membrane-supported
           methanol, dimethylether and dimethylcarbonate synthesis
    • Abstract: Publication date: 1 May 2015
      Source:Microporous and Mesoporous Materials, Volume 207
      Author(s): N. Wang , Y. Liu , A. Huang , J. Caro
      Hydrophilic LTA and SOD membranes have been tested in the selective water removal from methanol (MeOH), dimethylcarbonate (DMC) and dimethylether (DME) thus simulating their synthesis in membrane reactors with CO2 as feed. To further improve the pervaporation selectivity of LTA membranes for an aqueous MeOH solution, Na+ ions located in the 8-membered oxygen ring of LTA were ion-exchanged with larger K+ ions in a KNO3 solution, leading to an improvement of the pervaporation separation factor of the H2O/MeOH mixture from 2.8 to 7.4 at room temperature. Furthermore, the selective removal of steam from the organic compounds MeOH, DME and DMC on supported SOD membranes was investigated at high temperatures by steam permeation. The separation performances of SOD membranes for equimolar mixtures of steam with H2, CO2, MeOH, DME or DMC, were evaluated in the temperature range from 125 to 200 °C. The mixture separation factors for steam from DME and DMC through the SOD membrane were found to be higher than 200 and 1000, respectively.
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      PubDate: 2015-02-28T16:41:24Z
       
  • Preparation and optimization of mordenite nanocrystal-layered membrane for
           dehydration by pervaporation
    • Abstract: Publication date: 1 May 2015
      Source:Microporous and Mesoporous Materials, Volume 207
      Author(s): Yaqi Zhang , Yuta Nakasaka , Teruoki Tago , Aya Hirata , Yuki Sato , Takao Masuda
      Mordenite nanocrystal-layered membranes consisting of a mordenite nanocrystal layer and protection layer were successfully prepared. The obtained mordenite membranes were applied to the separation of water from water/organic solutions (organic solvents: ethanol, acetone, iso-propanol, or acetic acid) using a pervaporation method at temperatures from 60 to 100 °C. Water permeance through the mordenite membrane in each water/organic solution system was almost identical regardless of organic solvent types in the feed solution. In contrast, the permeance of the organic molecules depended on their polarities. The pre-aging temperature of the mother liquid and the heating rate for formation of the protection layer affected the secondary growth process that formed the protection layer, leading to different morphologies and sizes of the crystals in the protection layer. Water flux increased with decreasing crystal size in the protection layer because the number of non-zeolitic pores among the mordenite crystal increased as the crystal size decreased.
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      PubDate: 2015-02-28T16:41:24Z
       
  • Polyethylenimine functionalized halloysite nanotubes for efficient removal
           and fixation of Cr (VI)
    • Abstract: Publication date: 1 May 2015
      Source:Microporous and Mesoporous Materials, Volume 207
      Author(s): Xike Tian , Weiwei Wang , Yanxin Wang , Sridhar Komarneni , Chao Yang
      A typical nanoporous-geomaterial (halloysite nanotubes, HNTs) was functionalized by polyethyleneimine (PEI) grafting and the functionalized halloysite (PEI-HNTs) exhibited excellent performance for Cr (VI) removal from aqueous solution and immobilization by reduction. After PEI modification, the Cr (VI) uptake capacity of PEI-HNTs was about 64 times higher than that of the original HNTs and the maximum equilibrium removal capacity was found to be 102.5 mg g−1 at 328 K. Part of Cr (VI) was reduced to Cr (III) and then precipitated on the surface of adsorbent during the sorption process as determined by X-ray photoelectron spectroscopic analysis, suggesting that the PEI-HNTs are not only useful for Cr (VI) immobilization but also good for its reduction. The adsorption of Cr (VI) by the PEI-HNTs was fitted to Langmuir model and the kinetics of uptake could be described by a pseudo-second-order rate model very well. The results also demonstrated that PEI-HNTs could detoxify Cr (VI) at low pH value. The mechanism of uptake of Cr (VI) was postulated to be electrostatic interaction followed by its immobilization through reduction. The functionalized nano-geomaterial synthesized here could be a promising candidate of low cost for highly efficient Cr (VI) removal followed by its immobilization.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • Tunable coordinative defects in UHM-3 surface-mounted MOFs for gas
           adsorption and separation: A combined experimental and theoretical study
    • Abstract: Publication date: 1 May 2015
      Source:Microporous and Mesoporous Materials, Volume 207
      Author(s): Zhengbang Wang , Hikmet Sezen , Jinxuan Liu , Chengwu Yang , Stephanie E. Roggenbuck , Katharina Peikert , Michael Fröba , Andreas Mavrantonakis , Barbara Supronowicz , Thomas Heine , Hartmut Gliemann , Christof Wöll
      The metal organic framework (MOF) UHM-3, constructed with Cu(II)-paddle wheel-type nodes and a new tetracarboxylic acid linker, 5,5′-(dimethylsilanediyl)diisophthalate, has a close-packed alignment of open Cu(II) sites which are of interest for applications in gas storage and separation. Here, we first report on the growth of oriented, homogeneous and virtually defect-free (below 1%) UHM-3 MOF thin films on a solid substrate using a room-temperature liquid phase epitaxy (LPE) method. Thermal postsynthetic treatment allowed to induce Cu(I) defect sites in a controlled fashion. The interaction of CO and CO2 with the Cu(II) and Cu(I) sites was then studied using X-ray photoelectron spectroscopy (XPS) and IR-spectroscopy. The binding energy of these two species was determined using temperature-induced desorption. The interaction between the guest molecules and the Cu(I) and Cu(II) sites were also analyzed using density-functional theory (DFT). Surprisingly, both experiment and theory show that the binding energy of CO2 to Cu(I) and Cu(II) sites are essentially identical, in pronounced contrast to CO, which binds much stronger to Cu(I).
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • Novel method to synthesize highly ordered ethane-bridged PMOs under mild
           acidic conditions: Taking advantages of phosphoric acid
    • Abstract: Publication date: 1 May 2015
      Source:Microporous and Mesoporous Materials, Volume 207
      Author(s): Feng Lin , Xiangyan Meng , Elena Kukueva , Monika Kus , Myrjam Mertens , Sara Bals , Sabine Van Doorslaer , Pegie Cool
      Highly ordered SBA-15-type ethane-bridged PMOs have been obtained by employing H3PO4 as acid to tune the pH in the presence of copolymer surfactant P123. The effects of the acidity and the addition of inorganic salt on the formation of the mesostructure are investigated. It is found that, compared with HCl, the polyprotic weak acid H3PO4 is preferable for the synthesis of highly ordered SBA-15-type ethane-bridged PMOs with larger pore size and surface areas under mild acidic conditions. Moreover, taking the advantages of the mild acidic condition, vanadium-containing SBA-15-type ethane-bridged PMOs were successfully prepared through a direct synthesis approach. The XRD, N2-sorption, UV–Vis and CW-EPR studies of the V-PMO show that part of the vanadium species are present in polymeric (V–O–V)n clusters, while part of the vanadium centers are well-dispersed and immobilized on the inner surface of the mesopores.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • N-propylaniline functionalized 2D-hexagonal mesoporous silica as a highly
           selective fluorescence sensor for the detection of Hg(II) in water
    • Abstract: Publication date: 1 May 2015
      Source:Microporous and Mesoporous Materials, Volume 207
      Author(s): Ruth Gomes , Asim Bhaumik
      N-propylaniline functionalized 2D-hexagonal mesoporous SBA-15 material MFMS (monolayer N-propylaniline functionalized mesoporous SBA-15 type material) has been synthesized, where N-propylaniline group covalently grafted at the mesopore surface acts as a chromophoric fraction of the material for the sensing of metal ions from solutions. Powder XRD, HR TEM, FT IR, TGA, 13C/29Si solid state MAS-NMR, N2 sorption tools are employed to characterize the mesophase, framework-bonding and the surface properties of the material. Photoluminescence spectroscopy has been used to investigate the sensing behavior of this material towards various metal ions. This functionalized mesoporous material showed very high selectivity for sensing Hg2+ ions from its aqueous solution. With increasing concentration of Hg2+ ions from nanomolar to micromolar strength, strong fluorescence quenching is observed (upto 95.04%), while other main group and transition metal ions (Na+, K+, Ca2+, Mg2+, Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+) caused insignificant change in the fluorescent intensity of the material, suggesting future potential of MFMS as a highly selective Hg(II)-sensor.
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      PubDate: 2015-02-28T16:41:24Z
       
  • Ionic liquid assisted synthesis of flexible and super-hydrophobic porous
           gels
    • Abstract: Publication date: 1 May 2015
      Source:Microporous and Mesoporous Materials, Volume 207
      Author(s): Zhiqiao Qin , Yi Fang , Yanji Wang , Huanrong Li , Jinsheng Liang
      Herein we demonstrate the preparation of polysilane network-based aerogels through a facile one-pot reaction from co-precursor of trimethoxysilane and dimethoxysilane assisted with a carboxyl-functionalized ionic liquid for the first time. The gels show good absorption performance such as good selectivity, outstanding recyclability, simple recycling route, and robust stability, which make them highly appealing in the application as a sponge for quick separation of oily targets from water by absorption and simple mechanical squeezing. The resultant porous gels are highly flexible and super-hydrophobic, which are much lighter (0.075 g cm−3) and show larger absorption capacity for n-hexane than those obtained from diluted acetic acid.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • Comparing thresholding techniques for quantifying the dual porosity of
           Indiana Limestone and Pink Dolomite
    • Abstract: Publication date: 1 May 2015
      Source:Microporous and Mesoporous Materials, Volume 207
      Author(s): Marina Freire-Gormaly , Jonathan S. Ellis , Aimy Bazylak , Heather L. MacLean
      Carbonate reservoirs, and in particular, saline aquifers are globally abundant and promising for carbon dioxide (CO2) storage. Pore network modeling of CO2 storage in porous networks extracted from imaged carbonates provides a tool for evaluating potential storage sites. Capturing the multi-scale porosities (porosity at multiple length scales from nanometers to millimeters) inherent in carbonates is key to producing reliable pore network simulation results. Thresholding techniques that can extract the multi-scale pore space from micro computed tomography (microCT) or scanning electron microscopy (SEM) are needed. In this work, the application and evaluation of thresholding techniques originally developed for sandstones were applied and evaluated for Indiana Limestone and Pink Dolomite, carbonates that exhibit dual porosities (porosities that represent two distinct pore size distributions). The objective was to determine whether there is a single method or imaging technique that can reliably evaluate the porosity of carbonate rocks. The evaluation of the thresholding techniques applied to carbonate rocks showed that one single imaging technique or thresholding method cannot be solely used for all carbonate rocks. Instead, the evaluated porosity is a function of the microporosity, rock type and image resolution. The sensitivities of existing methods to thresholding techniques, imaging method and material structure were shown. This work provides a preliminary assessment of thresholding dual porosity carbonates.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • H2S interaction with HKUST-1 and ZIF-8 MOFs: A multitechnique study
    • Abstract: Publication date: 1 May 2015
      Source:Microporous and Mesoporous Materials, Volume 207
      Author(s): Jayashree Ethiraj , Francesca Bonino , Carlo Lamberti , Silvia Bordiga
      The interaction of H2S with HKUST-1 and ZIF-8 MOFs has been studied by means of FT-IR, Raman, DRUV-Vis-NIR and PXRD techniques. At very low equilibrium pressure (below 5 mbar) a stepwise structural distortion is observed in both HKUST-1 and ZIF-8. At higher equilibrium pressures (20–60 mbar), PXRD technique, in particular, showed the structural destruction of HKUST-1 with formation of a covallite (CuS) phase and some structural distortion of ZIF-8.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • Lysozyme specific aptamer immobilized MCM-41 silicate for single-step
           purification and quartz crystal microbalance (QCM)-based determination of
           lysozyme from chicken egg white
    • Abstract: Publication date: 1 May 2015
      Source:Microporous and Mesoporous Materials, Volume 207
      Author(s): Gulay Bayramoglu , V. Cengiz Ozalp , Meltem Yilmaz , Ulku Guler , Bekir Salih , M. Yakup Arica
      In the present study, MCM-41 silica particles were functionalized with 3-aminopropyltriethoxysilane (APTES) and characterized by FTIR, SEM, TEM and, Brunauer–Emmett–Teller (BET) analysis. A lysozyme specific aptamer was then immobilized onto amine functionalized MCM-41 particles via glutaraldehyde coupling, which were used for adsorption and purification of lysozyme. The effect of various parameters including pH, adsorbent dosage and lysozyme concentration on the lysozyme specific aptamer immobilized silica particles was evaluated. Efficiency of aptamer-silica particles in the purification of lysozyme from diluted chicken egg white was also realized. The optimal adsorption condition was in phosphate buffer (50 mmol L−1, pH 7.0) and the lysozyme adsorption capacity was 36.8 mg g−1 polymer. Increasing the initial lysozyme concentration and temperature had a positive effect on the binding capacity, whereas increasing the ionic strength resulted in the opposite effect. The recovery of adsorbed lysozyme by elution with glycine buffer (0.2 mol L−1, pH 2.0) was about 93%. Additionally, proteins with different isoelectric points (e.g. lysozyme, albumin, cytochrome c and hemoglobin) were used as model proteins to investigate the selectivity of the lysozyme binding aptamer. The lysozyme aptamer was used in the purification of lysozyme from diluted chicken egg white, which was verified by a single SDS-PAGE band. The reusability studies showed that, about 87% of the initial adsorption capacity of the aptamer immobilized particles could be maintained after 20 cycles of purification. Finally, the specific interaction between lysozyme specific aptamer sequences and lysozyme was investigated by quartz crystal microbalance (QCM) biosensor for determination of lysozyme in the egg samples.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • Effect of metal species on the morphology of metal (oxides) within
           mesochannels of SBA-15 via a double-solvent method
    • Abstract: Publication date: 1 May 2015
      Source:Microporous and Mesoporous Materials, Volume 207
      Author(s): Xiubing Huang , Guixia Zhao , Ge Wang , Yinhai Tang , Zhan Shi
      In this work, several kinds of nanostructured metal (Ag nanowires) or metal oxides (MnOx nanowires, Co3O4 nanoparticles, NiO nanoparticles, CuO nanoparticles) within the mesochannels of SBA-15 have been synthesized by a double-solvent method, in which n-hexane was used as a hydrophobic solvent and metal nitrate aqueous solution as a hydrophilic solvent. The influence of metal nitrate precursor species and concentration on the loading and morphology of metal (oxides) within the mesochannels of SBA-15 was investigated. XRD, N2 adsorption/desorption isotherms and HRTEM were used to characterize these composite materials. It is found that the growth nature of metal (oxides) as well as the confinement effect of mesoporous have great influence on their morphology within the mesochannels of SBA-15. These results in this research would give some instructive information for the morphology design of metal (oxide) with the use of nanoporous template.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • Plug precursor assisted synthesis: A highly efficient method of tuning the
           acidic and structural properties of Al-SBA-15
    • Abstract: Publication date: 1 May 2015
      Source:Microporous and Mesoporous Materials, Volume 207
      Author(s): Sen Lin , Lei Shi , Tingting Yu , Xuebing Li , Xianfeng Yi , Anmin Zheng
      An acid-free strategy shows high flexibility for tuning the structural properties of Al-SBA-15 mesoporous materials. Full-open-, plug-containing- and inkbottle-type mesostructures have been directly hydrothermally synthesized by simply adjusting the P123/Si molar ratio of the initial reaction mixture from 0.015 to 0.0020. When attaching a plug precursor addition process (denoted as Plug Precursor Assisted Synthesis, PPAS), the plug structure can be controllably generated inside the straight mesopores of the resulting Al-SBA-15. The plug-containing Al-SBA-15 sample showed that more than 43% of the mesopores were blocked by the plug structures, even with a P123/Si molar ratio condition of as high as 0.0075. More importantly, it exhibited stronger acid strength than an Al-SBA-15 sample possessing full-open-type mesopores, and was characterized by the strongest acidity with a pH value of around 2. The strong acid strength was due to aluminum migration and rearrangement, as well as to structural reconstruction during the hydrothermal treatment to form plugs, which also accelerated the generation of more tetrahedral-coordinated Al species with high accessibility. In contrast, a plug-containing Al-SBA-15 sample synthesized from an HCl aqueous medium has a relatively lower aluminum content and a weaker acid strength, although the pH value was measured to be ca. 2. To account for this result, negatively charged silica fragments are suggested to have been previously neutralized by H+ so that further interaction with Al3+ was suppressed. Therefore, the inclusion of aluminum into framework reconstruction in the subsequent hydrothermal treatment under an H+-rich synthesis condition was inhibited.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • Cordierite/steatite/CeO2 porous materials – Preparation, structural
           characterization and their photocatalytic activity
    • Abstract: Publication date: 1 May 2015
      Source:Microporous and Mesoporous Materials, Volume 207
      Author(s): Marta Valášková , Kamila Kočí , Jana Kupková
      The study is focused on structural characterization of new cordierite/steatite/CeO2 ceramic catalysts sintered from the mixtures containing vermiculite/CeO2 (Ver/CeO2) ceria precursor and testing their photocatalytic ability to decompose nitrous oxide (N2O). Two preceramic mixtures named A and B contained the amount of kaolinite (47 wt% and 50 wt%, respectively), different quantity of talc (40 wt% and 20 wt%, respectively) and vermiculite (13 and 30 wt%, respectively). Their counterpart mixtures A/CeO2 and B/CeO2 contained vermiculite/CeO2 instead of pure vermiculite. Ceramic cordierite/steatite (A and B) and cordierite/steatite/CeO2 (A/CeO2 and B/CeO2) sintered at 1300 °C were composed of indialite, hexagonal form of cordierite, orthorhombic protoenstatite and orthoenstatite, and CeO2 (3 wt% at A/CeO2 and 10 wt% at B/CeO2). The cordierite/steatite ceramic samples A and B showed the porosity 34 and 21%, respectively, a unimodal pore size distribution and the median pore diameter 22 and 15 μm, respectively. The cordierite/steatite/CeO2 samples A/CeO2 and B/CeO2 showed bimodal pore size distribution and porosity of 54 and 58%, respectively, and the median pore diameter 8 and 7 μm, respectively. A mean crystallite size D (220) of CeO2 was found for Ver/CeO2 = 8.5 ± 0.5 nm, A/CeO2 = 27.1 ± 2.8 nm and for B/CeO2 = 31.1 ± 3.0 nm. Photocatalytic decomposition of N2O over the ceramic samples A/CeO2 and B/CeO2 was performed during 20 h in annular batch reactor illuminated with 8 W Hg lamp (254 nm wavelength). Reaction kinetic corresponds to first-order reaction rate which is in agreement with plausible reaction mechanisms. The highest N2O conversion of 91% was achieved over the sample B/CeO2.
      Graphical abstract image

      PubDate: 2015-02-28T16:41:24Z
       
  • PVDF-MFI mixed matrix membranes as VOCs adsorbers
    • Abstract: Publication date: 1 May 2015
      Source:Microporous and Mesoporous Materials, Volume 207
      Author(s): M. Drobek , A. Figoli , S. Santoro , N. Navascués , J. Motuzas , S. Simone , C. Algieri , N. Gaeta , L. Querze , A. Trotta , G. Barbieri , R. Mallada , A. Julbe , E. Drioli
      This work focuses on the preparation of porous mixed matrix membranes (MMMs) by non-solvent induced phase separation (NIPS) using poly(vinylidenefluoride) (PVDF) as polymer and nano-sized silicalite-1 (S-1) and Ti-silicalite-1 (TS-1) seeds of MFI zeolite structure as inorganic fillers. These MMMs have been used as VOCs adsorbers. Different zeolite seed concentrations (up to 22 wt.%) were homogeneously dispersed into the polymeric matrix to evaluate the influence of the amount of zeolites on the membrane characteristics. In all cases, asymmetric porous membranes, made up of two layers were obtained: the bottom side exhibited spherulitic structure; whereas, at the top side, a smooth layer was observed. With respect to the neat PVDF membranes, the hydrophobic character was found to be improved by the zeolite addition; in particular S-1 nano-seeds. The mechanical properties of the membranes were reduced by the addition of the filler, although the mechanical resistance of the MMMs was still sufficiently preserved. Experiments of hexane adsorption were carried out in order to evaluate the performance of the adsorbers in Volatile Organic Compounds (VOCs) removal. The as-prepared composite porous membranes revealed high adsorption capacity, confirming their potential as adsorbers for removing VOCs traces from waste air environment.
      Graphical abstract image

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