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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  [2969 journals]
  • Single, binary, and mixture adsorption of nine organic contaminants onto a
           microporous and a microporous/mesoporous activated carbon cloth
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Sylvain Masson, Mickaël Gineys, Sandrine Delpeux-Ouldriane, Laurence Reinert, Sylvie Guittonneau, François Béguin, Laurent Duclaux
      The adsorption kinetics of nine contaminants (ibuprofen, carbamazepine, ofloxacin, bisphenol-A, diclofenac, mecoprop, pentachlorophenol, benzotriazol and caffeine) on a microporous and a microporous/mesoporous activated carbon cloth were studied in single, two-component and complete mixture at pH 7.5. Adsorption capacities at equilibrium were highest for the highly microporous carbon material, showing that pollutant adsorption mainly takes place in the micropores. This effect was more pronounced for small size adsorbates. Adsorption kinetics were increased for small size adsorbates thanks to their easy diffusion in the narrow porosity. Same behaviors were observed in the complex mixture containing the nine pollutants. Competition and sieving effects were observed in two-component mixtures, while considering two adsorbates having different molecular volumes, as for example caffeine and diclofenac. Moreover, the desorption of the co-adsorbates having the highest Gibbs energy value of adsorption determined from adsorption isotherms at 298 K (caffeine, mecoprop and benzotriazol) was observed for the kinetics of the complex mixture of the nine contaminants and of the two-component mixture. This desorption was provoked by the competition with the contaminants having lower Gibbs energy variation in single adsorption and thus strongly attracted at the adsorbent surface.
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      PubDate: 2016-07-17T05:50:49Z
       
  • A review of the influence of source material’s oxide composition on
           the compressive strength of geopolymer concrete
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): M. Srinivasula Reddy, P. Dinakar, B. Hanumantha Rao
      Off late, geopolymer concrete has gained significant attention in the construction industry because of the benefits that it brings via, by-product waste utilization, reduction in greenhouse gas emission. Studies reveal that the chemical oxide composition of the raw material (viz., fly ash) strongly influences the mechanical behavior and durability properties of geopolymer concrete. However, not many studies have paid attention towards the influence of an oxide percentage in the raw material on the compressive strength of the geopolymer concrete. In this paper, an attempt has been made to study the compressive strength behavior against the percentage of oxides (viz., SiO2, Al2O3, Fe2O3, CaO etc.) present in the raw material which were employed in the production of geopolymer concrete. In this extensive data has been collected from various earlier research publications. Trends for 7 & 28 day compressive strengths against individual oxide component percentages were developed, and it was observed that the strength of geopolymer concrete differs greatly with the variation in percentage of the individual oxide component. Also, each oxide has shown distinct influence on the compressive strength of geopolymer concrete. Further, it has been noticed that the compressive strength of a sample has been predominantly influenced by the percentage of alumina-silicate oxides, and whereas oxides like CaO and Fe2O3 even though lesser in amount compared to alumina-silicate oxides have shown a distinctive effect on the strength built-up. Also, the oxide molar ratios influence on the compressive strengths has been analysed and it was noticed that compared to individual oxide composition its influence is not major on the compressive strength development. Therefore, knowing the typical range of the major oxides percentage required for achieving superior compressive strength will be beneficial in developing concrete mix proportion.
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      PubDate: 2016-07-17T05:50:49Z
       
  • Innovative layer by layer and continuous growth methods for synthesis of
           ZIF-8 membrane on porous polymeric support using poly(ether-block-amide)
           as structure directing agent for gas separation
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): A. Jomekian, R.M. Behbahani, T. Mohammadi, A. Kargari
      Poly(ether-bock-amide) (Pebax grade 1657) was utilized as structure directing agent for fabrication of ZIF-8 membranes on polyphenylsulfone (PPSU) by layer-by-layer and continuous methods of growth. N2 adsorption, SEM, XRD, TGA and FTIR tests were applied to characterize the synthesized membranes. Polydimethylsiloxane (PDMS) was utilized to cover the possible surface defects of ZIF-8 membranes by dip coating method. The ideal performances of uncoated and coated synthesized ZIF-8 membranes were evaluated in separations of CO2/CH4, CO2/N2, H2/CH4 and H2/N2. The results showed that: 1- The coating of membranes by PDMS significantly enhanced the selectivity and decreased the permeance in almost all separation tests. 2- Higher numbers of cycles of solution changing in layer-by-layer method resulted in less permeable and more selective membranes. 3- Continuous growth method with PDMS coating lead to observation of maximum separation factors in many permeation tests: In permeances of 2.5 × 10−7 mol m−2 s−2 Pa−1 for H2 and 1.9 × 10−7 mol m−2 s−2 Pa−1 for CH4, exceptional ideal selectivities of 22.8, 20.8, 17.3 and 15.8 were obtained for H2/CH4, H2/N2, CO2/CH4 and CO2/N2, respectively.
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      PubDate: 2016-07-17T05:50:49Z
       
  • One-step synthesis of nano-porous monolithic polyimide aerogel
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Jinyoung Kim, Jinuk Kwon, Seung-Ik Kim, Myeongsoo Kim, Daero Lee, Sangrae Lee, Gunhwi Kim, Juheon Lee, Haksoo Han
      A facile one-step method for synthesis of a porous monolithic polyimide aerogel was successfully developed. The specific thermal curing, slow desiccating process and swelling method were used in synthesizing monolithic polyimide aerogel without any additional chemical reaction to create a connected structure among the polyimide-based spherical aerogel microparticles. Using this method, the monolithic polyimide aerogel can be easily fabricated whilst using no additional chemicals for crosslinking. This type of polyimide aerogel was produced homogeneously by the polyimidization of pyromellitic dianhydride (PMDA) and 4,4′-oxydianiline (ODA). The synthesized porous monolithic polyimide aerogel has many good properties which could be used in various industries, as it maintained a high thermal decomposition temperature (10% weight decomposition temperature: Td10%) of approximately 577 °C and a glass transition temperature (Tg) of 432 °C, with bulk density of 490.7 kg/m3, porosity of approximately 45% and average pore size of 4 nm (by nitrogen adsorption test) of polymer and 157 nm (by mercury intrusion method) of space observed in FE-SEM image. Also, the monolithic polyimide aerogel had an excellent oil-adsorbing capacity of 150%, and the adsorbed oil could be separated easily using a simple drying process. The dried monolithic polyimide aerogel showed significant recoverability and reusability of adsorbed oil. In addition, the monolithic polyimide aerogel exhibited high mechanical resistance such that the structure can withstand a high pressure greater than 122.3 kPa, under which the monolithic polyimide aerogel (MPA) was compressed but did not break. This type of MPA shows excellent thermal, mechanical properties and great processability, and could be the new candidate for high performance materials in various industries, especially catalyst field.
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      PubDate: 2016-07-17T05:50:49Z
       
  • Inside back cover - Contents (continued from back cover)
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232




      PubDate: 2016-07-17T05:50:49Z
       
  • Outside back cover (contents)
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232




      PubDate: 2016-07-17T05:50:49Z
       
  • Editorial Board
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232




      PubDate: 2016-07-17T05:50:49Z
       
  • Synthesis of mesoporous carbons with controlled morphology and pore
           diameters from SBA-15 prepared through the microwave-assisted process and
           their CO2 adsorption capacity
    • Abstract: Publication date: 1 October 2016
      Source:Microporous and Mesoporous Materials, Volume 233
      Author(s): Kripal S. Lakhi, Wang S. Cha, Jin-Ho Choy, Maryam Al-Ejji, Aboubakr M. Abdullah, Abdullah M. Al-Enizi, Ajayan Vinu
      Mesoporous carbon materials (CMK-3-T-MW) with high surface area, different pore diameters and rod shaped morphology were synthesized via nanocasting technique using the SBA-15 templates prepared by ultra-fast microwave-assisted process under static condition. The combined microwave and static approach offers the highly ordered rod shaped morphology to the SBA-15 template, which was successfully replicated into the mesoporous carbon materials. By tuning the synthesis temperature of the template, it is possible to fabricate mesoporous carbons with different pore diameters and specific surface areas. These excellent materials can be utilized for various applications and here we demonstrate their use as adsorbents for CO2 molecules. A significant enhancement in the adsorption of CO2 was achieved for the mesoporous carbon with rod shaped morphology, large pore diameter and high surface area. The adsorption capacity of CMK-3-T-MW was also compared with commercially available activated carbon, multi walled carbon nanotubes (MWCNTs) and 2D and 3D highly basic mesoporous carbon nitrides (MCNs). The CO2 adsorption capacity of mesoporous carbon with controlled morphology is 24.4 mmol/g at 273 K and 30 bar pressure which is much higher than that of mesoporous carbon CMK-3-HT (20.3 mmol/g at the same conditions) prepared by the conventional hydrothermal method, activated carbons, MWCNTs, and MCNs.
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      PubDate: 2016-07-17T05:50:49Z
       
  • Photoluminescent porous and layered lanthanide silicates: A review
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Bruno R. Figueiredo, Anabela A. Valente, Zhi Lin, Carlos Manuel Silva
      A large number of silicates containing transition metals and rare earth (in particular lanthanide) elements have been reported until recently. Generally, they exhibit a rich structural chemistry with interesting physical and chemical properties, and, in contrast to zeolites, which are built of [SiO4]4− and [AlO4]5− tetrahedrons, their frameworks embody metals in different coordination. In particular, materials containing rare earth and/or lanthanide elements may combine, in a single and stable solid, microporosity and tuneable optical properties. Such multi-functionality may be explored with interest, being a challenging approach to novel chemical and optical applications. This article aims to review rare earth and lanthanide silicates published to date, namely their relevant structure features and photoluminescent properties, being divided in two sections according to the major approaches used for their preparation, i.e. doping and embedding. The parent materials hosting the rare earth or lanthanide elements, the type and number of such emitters, and the disorder and dimensionality of the solids are some of the addressed topics. Furthermore, this review is also intended to highlight the great challenges that optical centres design offers in the field of material science. Some potential applications are also debated, such as wastewater remediation, nuclear medicine, imaging, and sensors. Notwithstanding the relevance that photoluminescent porous and layered lanthanide silicates may achieve in wastewater treatment, as a result of their stability and high selectivity combined with capacity, their sensing ability towards a specific ion or molecule will be for sure of capital importance in the near future.
      Graphical abstract image

      PubDate: 2016-07-17T05:50:49Z
       
  • The promoting effects of alkali metal oxide in side-chain alkylation of
           toluene with methanol over basic zeolite X
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): He Han, Min Liu, Xiaowa Nie, Fanshu Ding, Yiren Wang, Junjie Li, Xinwen Guo, Chunshan Song
      The side-chain alkylation of toluene with methanol was investigated on a series of catalysts which were prepared by ion-exchange or subsequent impregnation of zeolie X with potassium hydroxide or cesium hydroxide aqueous solution. The catalysts were characterized by X-ray diffraction, scanning electron microscopy, X-ray fluorescence, Ar physical adsorption-desorption, NH3 temperature-programmed desorption (TPD), CO2-TPD, pyridine adsorption Fourier-transform infrared (FT-IR) spectroscopy, FT-IR spectroscopy in OH stretch region, thermogravimetric/differential thermal analysis, ultraviolet-Raman spectroscopy, and X-ray photoelectron spectroscopy. It was found that alkali metal oxide played extremely important roles in the modification of catalysts and in the catalytic reaction pathway. Strong basic sites were formed by modification of basic zeolite X with alkali metal oxide. These basic sites promoted the dehydrogenation of methanol to formaldehyde which was recognized as the true alkylating agent in side-chain alkylation. Consequently, side-chain alkylation of toluene with formaldehyde was enhanced. As toluene was mainly adsorbed and activated on alkali metal cations bonded on the zeolite framework, the synergistic effects between alkali metal oxide and alkali metal cations were proposed. One of the possible reaction path ways for side-chain alkylation of toluene with methanol over basic zeolite was described. Alkali metal ion-exchanged zeolite X modified with alkali metal oxide demonstrated relatively high side-chain alkylation activity. However, the improvement of styrene selectivity faced with great challenges.
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      PubDate: 2016-07-17T05:50:49Z
       
  • Antimicrobial behavior of ion-exchanged zeolite X containing fragrance
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Rumeysa Tekin, Nurcan Bac
      Microporous zeolites are aluminosilicates composed of silicon, aluminum, and oxygen in a framework with cations. The cation contents can be exchanged with metal ions in order to add antimicrobial (antibacterial, anticandidal, and antifungal) properties. Zeolites has also recently been acquainted with fragrance applications to tailor products with controlled release properties. Here, a new application of ion exchanged zeolite X combined with adsorption properties is presented. In this study, zeolite X crystals were ion-exchanged with Zn2+ and Cu2+ ions and encapsulation of a fragrance molecule, triplal, was studied using ion-exchanged zeolite X as a fragrance carrier. The antimicrobial behavior of ion-exchanged zeolite X before and after encapsulation were investigated by disc diffusion method. Zn2+ and Cu2+ loaded zeolite samples showed excellent antimicrobial activities against three bacteria Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa, a yeast Candida albicans and a fungus Aspergillus niger. Ion-exchanged zeolite X samples containing triplal sustained antimicrobial activities after the encapsulation process.
      Graphical abstract image

      PubDate: 2016-07-17T05:50:49Z
       
  • Boosting the solar-light-driven methanol production through CO2
           photoreduction by loading Cu2O on TiO2-pillared K2Ti4O9
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Maurício Alves Melo Júnior, Andreia Morais, Ana F. Nogueira
      The enhancement of the photoactivity of the layered semiconductor K2Ti4O9 towards the greenhouse CO2 gas photoreduction is reported in this work. Such improvement was due to the synergistic effect created by pillaring K2Ti4O9 with TiO2 pillars and the subsequent loading of Cu2O cocatalyst. A throughout characterization of the final nanocomposite and the intermediate materials was carried out in order to evaluate the structural and compositional features responsible for the increased photocatalytic activity. The layered precursor phase (K2Ti4O9), the incorporation of anatase TiO2 pillars and cuprite Cu2O nanoparticles were studied through X-ray diffractometry, electron microscopy analyses and X-ray photoelectron spectroscopy. All the successive reactions performed in the layered precursor led to the increment of its surface area, from 25 to 145 m2 g−1, and mesoporosity (4.6 nm), as indicated by N2 adsorption-desorption isotherms. The pillaring and the loading of Cu2O nanoparticles have red shifted the onset of the absorption band of the semiconductor, broadening the optical response of the final nanocomposite. All these modifications enhanced the activity of the photocatalyst, doubling the production of methanol compared to the pristine K2Ti4O9.
      Graphical abstract image

      PubDate: 2016-07-17T05:50:49Z
       
  • Post-synthetic improvement of H-ZSM-22 zeolites for the methanol-to-olefin
           conversion
    • Abstract: Publication date: 1 October 2016
      Source:Microporous and Mesoporous Materials, Volume 233
      Author(s): Michael Dyballa, Utz Obenaus, Melanie Rosenberger, Achim Fischer, Harald Jakob, Elias Klemm, Michael Hunger
      Microporous ZSM-22 zeolites (structure type TON) were modified by treatments with different alkaline solutions for introducing mesopores. This surprisingly affected the nature and the density of both SiOH groups and Brønsted acid sites significantly, while the Brønsted acid strength was maintained. The catalyst lifetime in the methanol-to-olefin (MTO) conversion could be enhanced by a factor of up to 2 for an optimum Brønsted acid site density of 0.34 mmol/g, which was also accompanied by the highest propene selectivity of 48%. The product distributions of the parent microporous and the modified mesoporous ZSM-22 catalysts were very similar. This indicates that the shape selectivity of the modified ZSM-22 zeolites in the MTO conversion is mainly determined by the 10-ring pore system and not affected by introduced mesopores. Therefore, it can be excluded that catalysis near the pore mouths plays a significant role in the MTO conversion on ZSM-22 zeolites.
      Graphical abstract image

      PubDate: 2016-07-12T04:58:07Z
       
  • Catalytic properties of microporous zeolites in the synthesis of octyl
           glucoside from D-glucose with 1-octanol by single-step direct
           glucosidation
    • Abstract: Publication date: 1 October 2016
      Source:Microporous and Mesoporous Materials, Volume 233
      Author(s): Kyong-Hwan Chung, Sung-Jin Lee, Heon Lee, Hangun Kim, Young-Kwon Park, Byung-Hoon Kim, Sang-Chul Jung
      Catalytic properties of various microporous zeolites consisted of different acidic properties and pore topologies were studied in the synthesis of octyl glucoside from D-glucose with 1-octanol by single-step direct glucosidation. The influences of acidic properties and pore topologies of the zeolite catalysts were evaluated relating to the conversion of glucose and selectivities of octyl glucosides. The octyl glucosides could be synthesized conveniently by the single-step direct glucosidation through aging of reactants without further pre-treatment or additional supply of reactant. The reusability of the zeolite catalyst was evaluated to the used zeolite. The high conversion of D-glucose was obtained on H+ ion exchanged FAU (H-FAU) zeolite which has a mild acid strength. The conversion and yield were improved with increasing of acid site amount of the zeolite catalysts. H-FAU zeolite catalysts exhibited high octyl glucopyranoside selectivity owing to relatively a large pore cavity and a high concentration of mild acid sites. The selectivities of the octyl glucoside isomers were mainly depended on the differences of pore structure and concentration of acid sites of the zeolite catalysts. The zeolite used in the reaction was able to reuse through the regeneration process.
      Graphical abstract image

      PubDate: 2016-07-12T04:58:07Z
       
  • A unified kinetic model for adsorption and desorption – Applied to
           water on zeolite
    • Abstract: Publication date: 1 October 2016
      Source:Microporous and Mesoporous Materials, Volume 233
      Author(s): Marco Gaulke, Viktor Guschin, Sebastian Knapp, Sandra Pappert, Wilhelm Eckl
      A kinetic model for reversible adsorption and desorption processes under non-isothermal conditions based on reaction kinetics is deduced. This is done by explicit temperature dependence of all equations of the model. However in the performed experiments the coupling with the thermal bath was strong enough to neglect thermal conductivity and set the temperature as a timely-varying and spacial-constant parameter. Furthermore adsorption- and desorption-mechanisms of higher order and diffusion are considered. The formulation with partial differential equations is adaptable to the geometry of the adsorbent. To solve the system of coupled differential equations numerical methods of Wolfram Mathematica® are used. This model is applied to water on zeolite 3A. Beside the non-isothermal thermogravimetric analysis and the differential scanning calorimetry an isothermal experiment for the time-dependent measurement of the adsorption is used to evaluate the model. The sorption isotherms of a commercial zeolite manufacturer serve as a further source of comparison. The parameters are fitted numerically with the χ 2 -method to the experimental data. As a result of this paper a unified sorption model is introduced.
      Graphical abstract image

      PubDate: 2016-07-12T04:58:07Z
       
  • Effective hierarchization of TS-1 and its catalytic performance in
           cyclohexene epoxidation
    • Abstract: Publication date: 1 October 2016
      Source:Microporous and Mesoporous Materials, Volume 233
      Author(s): Justyna Tekla, Karolina A. Tarach, Zbigniew Olejniczak, Vladimir Girman, Kinga Góra-Marek
      The presented data showed that the chemical treatment of TS-1 with alkaline medium resulted in the formation of highly developed hierarchical structures. The esterification of the hydroxyl groups by methanol allowed modifying the hydrophobicity of TS-1 surface and obtaining truly micro/mesoporous material. The preservation of microporous characteristics was confirmed by XRD and low temperature nitrogen sorption studies. Detailed information on acidic properties of mesoporous titanosilicalites was delivered by IR studies of pyridine sorption and implicitly from 29Si MAS NMR investigations. Well-developed internal mesoporosity together with the retaining of Ti4+ atoms in tetrahedral framework positions offered 7-fold higher catalytic activity for the conversion of cyclohexene molecules than the native microporous TS-1. The selectivity to epoxide reached the value of 96% for the most efficient mesoporous titanosilicate.
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      PubDate: 2016-07-03T21:12:26Z
       
  • Porous organic polymer bifunctionalized with triazine and thiophene groups
           as a novel adsorbent for removing Cu (II)
    • Abstract: Publication date: 1 October 2016
      Source:Microporous and Mesoporous Materials, Volume 233
      Author(s): Yan He, Qinqin Liu, Fei Liu, Chensheng Huang, Changjun Peng, Qiang Yang, Hualin Wang, Jun Hu, Honglai Liu
      A triazine and thiophene bifunctionalized task-specific porous organic polymer with N and S atoms (TSP-NS) was synthesized from a simple one-step Friedel-Crafts reaction. The resulting novel porous polymer was determined to be highly effective in removing Cu (II) from aqueous solution. The maximum adsorption capacity, qmax, evaluated from the Langmuir model was 98.33 mg g−1. Moreover, the combination of experimental FTIR results and the theoretical quantum calculation demonstrated that the N and S heteroatoms of the bifunctionalized TSP-NS could easily form coordination complexes with Cu (II), which were responsible for efficient adsorption. The generated TSP-NS could be regenerated effectively and recycled at least five times without significant loss of adsorption capacity. Therefore, the convenience and low cost of synthesis, as well as the excellent adsorption capacity and reusability, made bifunctionalized polymer TSP-NS an attractive adsorbent for removing toxic metal ions from aqueous solution.
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      PubDate: 2016-07-03T21:12:26Z
       
  • Prediction of pore properties of hierarchical porous silica templated on
           natural rubber
    • Abstract: Publication date: 1 October 2016
      Source:Microporous and Mesoporous Materials, Volume 233
      Author(s): Issaree Ong-on, Ben Embley, Yusuf Chisti, Nanthiya Hansupalak
      Hierarchical porous silica (HPS) templated on natural rubber (NR) was made via sol-gel technique using sodium silicate as a silica source. Macropores and mesopores with an ink-bottle type of morphology were randomly distributed in the HPS. Prediction of surface area and pore volume of the produced HPS was undertaken by central composite design (CCD) and artificial neural network (ANN) models, which were separately developed and which made use of the following variables: pH, calcination temperature, NR amount, and salt concentration. To obtain optimum feedforward back propagation networks, the number of hidden layers and the number of neurons in each hidden layer were varied. The use of an extra dataset in developing the optimum ANN architecture in each training cycle helped to easily locate when and where the overfitting phenomenon occurred, and thus the generalization performance of a network was not compromised. The quadratic polynomial models obtained using CCD poorly predicted surface area and pore volume (R 2 < 0.65). In contrast, the optimum ANN models with a single hidden layer predicted both pore properties exceptionally well (R 2 > 0.95).
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      PubDate: 2016-07-03T21:12:26Z
       
  • Adsorption of pharmaceuticals in water using Fe3O4 coated polymer clay
           composite
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): V. Arya, Ligy Philip
      Adsorption of three pharmaceuticals, namely, atenolol, ciprofloxacin and gemfibrozil using synthesized magnetic polymer clay composite was investigated in detail by conducting batch kinetic, equilibrium and desorption experiments. Optimum ratio of composite adsorbent was found to be clay: chitosan: powdered activated carbon (PAC): magnetic nano particles (MNP) as 1:0.5:0.3:0.3. Characterization studies showed the incorporation of modifiers into the clay structure. Surface area of the synthesized pellets was 94.81 m2/g with mesoporous surface. Freundlich model was able to predict the adsorption equilibrium data. Maximum adsorption capacities were estimated to be 15.6, 39.1 and 24.8 mg/g for atenolol, ciprofloxacin and gemfibrozil, respectively. The main driving force of adsorption was electrostatic interaction. The adsorbent performance was affected at lower and higher pH and by the presence of humic acid. Desorption of atenolol and ciprofloxacin were significantly higher in acid and alkaline solution whereas gemfibrozil was desorbed upto 70% in methanol. Magnetically separable clay composite was found to be a suitable adsorbent for removing pharmaceuticals from water.
      Graphical abstract image

      PubDate: 2016-07-03T21:12:26Z
       
  • Microwave-assisted synthesis of ultra small bare gold clusters supported
           over Al2O3 and TiO2 as catalysts in reduction of 4-nitrophenol to
           4-aminophenol
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): Mostafa Farrag
      In this work I present a novel method to prepare ultra small bare gold clusters (Aun) loaded over different supports. Size selected gold clusters protected by glutathione ligand (Au25(SG)18) was prepared and deposited over aluminium dioxide (Al2O3 Puralox SCCa-190HPV) and anatase titanium dioxide (TiO2) by impregnation method with doping percentage 0.5 and 1 wt %. Then the doped catalysts were irradiated 1 h by microwave synthesis labstation at 80 °C and 500 W to remove the glutathione ligands (GSH) and leave the bare gold clusters (Au25) supported over alumina and titania as a strategy for enhancing their catalytic activity and selectivity. The high resolution transmission electron microscope analysis confirmed the particle size of protected (1 wt % Au25(SG)18/Al2O3) and bare (1 wt % Au25/Al2O3) gold clusters over alumina have the same size distribution (∼1 nm). The TEM images of doped gold clusters over TiO2 before and after microwave treatment are clearer than alumina. This means the gold clusters over alumina and titania did not suffer from any agglomeration by microwave treatment. From nitrogen sorption isotherms at −196 °C for the protected and bare gold clusters over supports showed two different loop types of isotherms H3 and H1, respectively. Their specific surface area SBET, pore volume and average pore diameter were calculated. The pore size distribution of supported gold clusters before and after microwave treatment was measured. These results confirmed the ligands were removed from the supported gold clusters by microwave treatment. The pores in alumina and titania which were blocked by the protected clusters have become available. Reduction of 4-nitrophenol (4-NP) into 4-aminophenol (4-AP) in presence of NaBH4 was used as a test reaction to compare the catalytic activity of supported bare and protected gold clusters over alumina. The results showed that the 1 wt % Au25/Al2O3 catalyst exhibited the best catalytic performance in the reduction of 4-NP into 4-AP and revealed 100% conversion following 90 s stirring at room temperature. The extreme catalytic activity of the ultra small gold clusters attributed to their electronic properties and geometrical configuration.
      Graphical abstract image

      PubDate: 2016-06-28T20:47:20Z
       
  • Porosity in ion-exchanged and acid activated clays evaluated using
           n-nonane pre-adsorption
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): M.M.L. Ribeiro Carrott, I.P.P. Cansado, P.J.M. Carrott, P.A. Russo, P. Castilho, C. Fernandes, C. Catrinescu, C. Breen
      The applicability of the n-nonane pre-adsorption method for characterising the porosity in clays is presented. Na-SD, a Na+-exchanged purified bentonite, and materials obtained by Al3+-exchange and acid treatments of Na-SD and SAz-1 were used. Nitrogen adsorption isotherms, at −196 °C, were determined before and after n-nonane pre-adsorption on each of the samples. In all materials, n-nonane remained adsorbed in ultramicropores after outgassing at 25 °C. Outgassing at higher temperatures (50, 75 and 200 °C) removed nonane and ultramicropores became available for nitrogen adsorption. All treatments on Na-SD led to increase in micropore volume. Larger ultramicropore and supermicropore volumes were obtained for Na-SD acid activated with HCl at 95 °C than for treatments at 25 °C with HCl or following Al3+-exchange (Al-SD), and increased with increasing acid concentration to 3 M. Activation with 4 M HCl led to the largest pore volume with contribution from mesopores. However, the specific external surface area was the same as that obtained for Na-SD, Al-SD and for most of the other acid activated samples. Treatments at 95 °C with 1 M and 6 M HCl promoted increase in specific external surface area. The micropore volumes and specific external surface area for SAz-1 treated with 1 M HCl at 95 °C were larger than those of Al-SAz-1, but lower than those obtained for corresponding materials derived from Na-SD. The n-nonane pre-adsorption method enabled micropore volumes and specific external surface areas to be obtained for all samples.
      Graphical abstract image

      PubDate: 2016-06-28T20:47:20Z
       
  • Design of multifunctional magnetic hybrid silica aerogels with improved
           properties
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): Hajar Maleki, Luísa Durães, Benilde F.O. Costa, Rúben F. Santos, António Portugal
      A streamlined synthesis approach is proposed to develop a multifunctional magnetite doped hybrid silica aerogel by taking advantage of the versatility of the sol-gel process and flexibility of the crosslinking reaction. To this avail, magnetite NPs, at concentrations from 0.05 to 0.2 mg/mL, were mixed at the nanoscale with the initial solution containing the silica precursors and the crosslinker. For an effective and sustainable linkage of magnetite to the silica network, the surface of the magnetite was chemically coated with an active silylation agent to compatibilize the surface chemistry of these nanoparticles with the chemistry of silica. It has been shown that at a certain dopant concentration, the magnetite doped aerogels gained several interesting improvements in the final properties over their undoped counterparts, particularly an increase in the compressive strength (up to 2.6 MPa, with ca. 3× increase) with only a marginal increase in the density (up to ∼ 0.29 g cm−3, with 20% increment) and decrease in the active surface area (down to ∼ 49 m2 g−1 and 7% reduction). Importantly, a good deal of improvement regarding the thermal insulation performance for doped aerogels has been obtained due to the opacification behavior of the magnetite dopants at temperatures above 300 K. The significant improvements concerning the physical and mechanical properties combined with the magnetic properties (up to 11 emu g−1 at room temperature) make these multifunctional hybrid aerogels suitable for some applications, ranging from selective magnetic separation for environmental cleaning and magnetic drug delivery to catalysis, etc.
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      PubDate: 2016-06-28T20:47:20Z
       
  • Synthesis of ferrierite by a new combination of co-structure-directing
           agents: 1,6-bis(N-methylpyrrolidinium)hexane and tetramethylammonium
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): Ramon K.S. Almeida, Luis Gómez-Hortigüela, Ana B. Pinar, Joaquín Peréz-Pariente
      Ferrierite zeolite was synthesized in fluoride medium using dicationic 1,6-bis(N-methylpyrrolidinium)hexane (MPH) as a bulky structure directing agent (SDA) in combination with tetramethylammonium (TMA) as a small co-structure-directing agent (co-SDA). When trimethylamine, pyrrole or tert-butylamine were used as co-SDA, amorphous and beta zeolite (BEA framework type) were obtained, suggesting that these amines do not play a strong role as co-SDA. Only when TMA was used as co-SDA in synthesis gels with moderate pH, ferrierite is obtained; in fact, we have found a dramatic influence of the pH of the synthesis gel on the ferrierite crystallization, since even using TMA as co-SDA, ferrierite was only obtained under moderate pH values. Interestingly, ICP and CHN chemical analyses suggest that the Al content is driven by the amount of SDAs able to be hosted within the ferrierite framework, more specifically, by the nitrogen (positive charge) content available to charge-balance the negative charge associated to the incorporation of Al. A computational study showed that the most stable configuration of the ferrierite system corresponds to the occupation of the FER cages by TMA, while MPH accommodates in the 10-membered ring channels of the FER structure; the packing arrangement of MPH determines the density of positive charges, and hence the Al incorporation. Moreover, the unit cell parameters of the as-made ferrierite samples indicate that the structure is slightly expanded along the [100] direction in order to accommodate the bulky MPH dication.
      Graphical abstract image

      PubDate: 2016-06-28T20:47:20Z
       
  • Microporous-crystalline microfibers by eco-friendly guests: An efficient
           tool for sorption of volatile organic pollutants
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): Christophe Daniel, Pasqualmorica Antico, Hideaki Yamaguchi, Masami Kogure, Gaetano Guerra
      Syndiotactic polystyrene (s-PS) microfibers with a microporous crystalline form have been successfully prepared with eco-friendly solvents through a cost effective process, which can be easily scaled up for large scale production. These microporous fibers are characterized by high sorption capacity and fast sorption kinetics of volatile organic compounds from air, which are comparable with those of Tenax®, a commercial benchmark sorption material. Excellent sorption properties, associated with safe and manageable morphology as well as simple and eco-friendly preparation/regeneration procedures, make these microporous s-PS microfibers particularly suitable as filter sorption medium to remove traces of pollutants from moist air.
      Graphical abstract image

      PubDate: 2016-06-28T20:47:20Z
       
  • Microwave-assisted hydrothermal synthesis of mordenite zeolite:
           Optimization of synthesis parameters
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): Umer Khalil, Oki Muraza
      Sustainable industrial processes demand rapid and cost-effective synthesis procedures of zeolites. Herein, we report the synthesis zone of pure mordenite (MOR) zeolite under microwave irradiations. Phase purity, crystallinity, and morphology were carefully studied through optimization of synthesis parameters such as crystallization time, aging time and Si/Al ratio. Without the seeds, the organic-structure directing agent (OSDA)-free synthesis of pure MOR crystals was achieved in the shortest time of 12 h. Moreover, the addition of two different OSDAs, namely o-phenylenediamine (OPDA) and tetramethylammonium hydroxide (TEAOH), decreases the crystallization time up to 6 h with the same gel composition. Whereas, minimum crystallization time through conventional heating was 24 h with an OSDA and 48 h without the template. Rectangular and spherical shaped crystals with low aspect ratio were formed under this condition. The same optimized condition was used with different gel compositions (i.e. Si/Al of 15, 25, 50) to crystallize pure MOR. Also, effect of alkalinity was investigated at different Si/Al ratios.
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      PubDate: 2016-06-28T20:47:20Z
       
  • Porous carbons from inverse vulcanised polymers
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): Joseph C. Bear, James D. McGettrick, Ivan P. Parkin, Charles W. Dunnill, Tom Hasell
      Elemental sulfur is an underutilised industrial by-product. It has been recently shown that it can be simply and scalably co-polymerised, by “inverse vulcanisation” with organic crosslinkers. The properties of porous carbons, which have extensive uses in science and industry, are influenced by the materials from which they are generated. Reported here are the first examples of porous carbons produced from high-sulfur inverse vulcanised polymers. The materials produced show micro-porosity, gas selectivity, and are doped with sulfur. The simplicity of the technique, and wide range of other potential inverse vulcanised feedstocks, gives scope for transferability and control of properties.
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      PubDate: 2016-06-28T20:47:20Z
       
  • Development of oxygen carriers for chemical looping combustion: effects of
           support microstructure on the performance of oxygen carriers
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): Yujing Liu, Peter Kirchesch, Arndt Remhof, Thomas Graule, Antje Liersch, Frank Clemens
      CO2 capture drives considerable R&D inputs into the advancement of chemical looping combustion (CLC) process, which is a promising and efficient technology to generate pure CO2 exhaust from fossil fuel powered plants. In the CLC process, oxygen storage material or oxygen carriers, composed of active metal oxides and supports, play critical roles by transferring combustion needed oxygen from air reactor to combustion reactor. To develop high performance oxygen carriers, the choice of supports as well as the effect of its microstructural characteristics is well worth to be studied. In this work, by taking CuO as active metal oxide and silica as supporting material, we investigated the relationship between the performance of CuO oxygen carrier and the microstructural characteristics of silica supports. The main messages of this work can be classified into: 1) with our recently developed ‘CIP-filtration’ method, the porous microstructure of silica supports was able to be tuned and a series of silica granules with varied pore volume, open porosity as well as pore size distributions were fabricated; 2) via the employment of dry impregnation method, CuO was loaded onto the silica granules and the loading amount shows a linear relationship with the open porosity of supports. A high loading amount of 50 wt% was already achieved with a only 2-cycle impregnation procedure, which is much more efficient than literature work; 3) the oxygen transport capacity of fabricated CuO oxygen carrier shows a strong reliance on the loading amount of CuO, while the conversion rate of CuO increases with the increase of supports open porosity, and the reaction rates of CuO oxygen carrier was assumed to be related with the pore size variation caused size difference of CuO units.
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      PubDate: 2016-06-28T20:47:20Z
       
  • Iron loaded EMT nanosized zeolite with high affinity towards CO2 and NO
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): Veselina Georgieva, Clément Anfray, Richard Retoux, Valentin Valtchev, Samuel Valable, Svetlana Mintova
      The preparation of iron-loaded nanosized zeolite with EMT-type structure (Fe-EMT) is reported. The sorption capacity of the Fe-EMT zeolite crystals for NO and CO2 is evaluated. The application of Fe-EMT zeolite as a gas delivery system with high capacity for CO2 and NO in biomedicine is considered. Therefore the toxicity of the pure EMT and Fe-EMT zeolite nanocrystals is studied. Primary culture of astrocytes was exposed to zeolite nanocrystals. In addition, two human cell lines, U87-MG glioblastoma and HEK-293T were used. Cells were exposed to zeolites nanocrystals with concentrations of 50, 100 and 400 μg/ml for 24 h and 48 h. Cytotoxicity was assessed by a cell viability assay and no alteration of cell viability exposed to zeolite nanoparticles was observed.
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      PubDate: 2016-06-28T20:47:20Z
       
  • Asymmetric polysilazane-derived ceramic structures with multiscalar
           porosity for membrane applications
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): Thomas Konegger, Chen-Chih Tsai, Herwig Peterlik, Stephen E. Creager, Rajendra K. Bordia
      Novel ceramic structures with multi-scalar porosity were developed using a single preceramic poly(vinyl)silazane to generate asymmetric Si-C-N-based membranes through pyrolytic conversion. Macroporous supports in planar-disc configuration were prepared through a sacrificial filler approach, intermediate structures and microporous layers were deposited via dip-coating. Microporosity in the selective layer was generated through a controlled thermal decomposition of the precursor component in nitrogen atmosphere at temperatures up to 600 °C, resulting in micropores with average pore sizes of 0.8 nm, as investigated by nitrogen adsorption and small-angle X-ray scattering (SAXS). The general feasibility of the single-precursor approach towards selective permeation of gaseous species was demonstrated by the investigation of gas permeances of the generated structures using single-gas permeance testing of He, N2, Ar, C2H6, and CO2. By variation of the deposition sequence during preparation of the selective layer by dip-coating, asymmetric structures with ideal permselectivities exceeding predicted Knudsen values were obtained. At 500 °C, He/N2 and He/CO2 permselectivities of up to 3.1 and 4.1 were found, respectively, at He permeances up to 3 × 10−8 mol m−2 Pa−1 s−1. The new single-material system is a first step towards the potential establishment of new, alternative membrane materials systems, circumventing thermal and chemical incompatibilities between constituents, and increasing material performance due to the applicability under extreme operating conditions.
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      PubDate: 2016-06-28T20:47:20Z
       
  • Editorial Board
    • Abstract: Publication date: 1 September 2016
      Source:Microporous and Mesoporous Materials, Volume 231




      PubDate: 2016-06-23T09:29:22Z
       
  • Sound transmission loss from polyvinyl acetate polymer mixed with
           different porous carbons
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): Mohammad Mahmudul Huq, Pei-Qi Chen, Chien-Te Hsieh, Hsi-Chi Yang, Tsung-Pin Tasi
      The soundproofing properties of microporous activated carbon (AC) and mesoporous carbon nanotube (CNT) in a polymer matrix (polyvinyl acetate, PVA) have been systematically investigated. Analyzed by N2-adsorption technique, the AC powders are mainly microporous, while the CNT powders consisted of a large number of mesoporous channels. An anechoic termination method is adopted to analyze the sound transmission loss (TL) for PVA-based coatings at different frequencies ranging from 400 to 3000 Hz. Pristine PVA, AC-PVA, CNT-PVA, and AC-CNT-PVA coatings showed average TL values of 24.4, 25.1 and 27.2, and 25.9 dB, respectively. The TL value as an increasing function of mesopore fraction reflects that the mesopore is a major contributor to the improved soundproof performance, while the aid of micropore seems to be minor. The improved TL can be attributed to the fact that the mesopore of CNTs is capable of providing a large number of voids and cavities for air storage, enhancing efficiency of sound absorption and reduces sound vibration. On the basis, the selection of porous carbons plays an important role in determining the soundproof performance of PVA-based coating. This design of soundproof coating delivers a feasible potential as eco-environmental decoration materials due to its good stability, non-toxicity, and excellent soundproof performance.
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      PubDate: 2016-06-23T09:29:22Z
       
  • Size-selective epoxidation of olefins in two new metal-organic framework
           constructed from six-coordinated tetranuclear Cu(II) SBUs
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): Chao Chen, Pan Shen, Mingming Wan, Nan Ding, Xiaotong Shi, Xiaolei Wang, Ning Zhang
      Two metal-organic frameworks (MOFs) constructed from new six-coordinated tetranuclear Cu(II) secondary building units (SBUs) and 1-(3,5-dicarboxyphenyl)-2,5-dimethyl-1H-pyrrole-3,4-dicarboxylic acid (H4ppdc) ligands have been synthesized under solvothermal condition. Their similar, high density tetranuclear Cu(II) SBUs but different, well-defined microporous structures encourage us to contrastively study their catalytic behaviour for the epoxidation reaction of olefins using TBHP or molecular oxygen as oxidants. The results show that the two MOFs exhibit good size-selectivity for the epoxidation of different olefin substrates. The catalytic mechanism investigation indicates that the reaction process indeed proceeds via radical epoxidation.
      Graphical abstract image

      PubDate: 2016-06-23T09:29:22Z
       
  • Synthesis and characterization of zeolite based nano–composite: An
           environment friendly slow release fertilizer
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): Ambreen Lateef, Rabia Nazir, Nadia Jamil, Shahzad Alam, Raza Shah, Muhammad Naeem Khan, Murtaza Saleem
      The research deals with assessing the feasibility of using nano-zeolite as support material for the provision of nine out of thirteen primary, secondary and micro-nutrients on slow release basis. The nano-zeolite (NZ) and nano-composite (ZNC), synthesized using simple chemical approach, were characterized by different techniques including FT-IR, powder XRD, SEM/EDX, AFM and TGA/DSC. Physical characterization was also performed by using standard methods. The lab studies showed that there is considerable increase in water retention capacity, water absorbency, equilibrium water content and swelling ratio of ZNC as compared to the NZ which is favorable for maintaining water level in the soil. The nano-composite prepared is safe to use as compared to conventional fertilizers as indicated by salt index value. Nutrients slow release studies carried out in water and soil confirmed the long term availability of all the doped nutrients to the plant over the full crop cultivation period that is suitable for promoting germination, growth, flowering and fruiting. Hence, the results obtained showed that the prepared nano-composite materials can be safely used as environment friendly fertilizer.
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      PubDate: 2016-06-23T09:29:22Z
       
  • Synthesis of [Mg2(DOBDC)(DMF)2]@polystyrene composite and its carbon
           dioxide adsorption
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): Hyun-Sik Moon, Jong-Ho Moon, Dong Hyuk Chun, Young Cheol Park, Yang No Yun, Muhammad Sohail, Kangkyun Baek, Hyunuk Kim
      [Mg2(DOBDC)] (Mg-MOF-74 or CPO-27-Mg) with open metal sites showed an exceptionally high CO2 uptake at low partial pressure and room temperature. The single-crystal structure of [Mg2(DOBDC)], however, has not been reported so far. In this work, we synthesized the crystalline product of [Mg2(DOBDC)(DMF)2] (1) and determined its single-crystal structure by synchrotron X-ray diffraction analysis. To improve the chemical stability and fabrication of the adsorbent, the composite of 1 and polystyrene (PS) was prepared by a simply solution-mixing method. Powder X-ray diffraction pattern of 1@PS revealed that the crystallinity of 1 is intact after incorporating PS. TGA of the composite revealed that 2.2 wt% of PS are incorporated to 1. CO2 sorption isotherms of activated 1@PS were measured in the temperature range between 283 and 303 K. The enthalpy of CO2 adsorption for activated 1@PS estimated by the virial equation at zero coverage is 43.9 kJmol−1, which is comparable to the reported value (47 kJmol−1) of activated 1. Interestingly, this composite showed high moisture stability after 90% humidity exposure for 1 day.
      Graphical abstract image

      PubDate: 2016-06-23T09:29:22Z
       
  • One-step oxidehydration of glycerol to acrylic acid using ETS-10-like
           vanadosilicates
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): Alex Silva Paula, Luiz Gustavo Possato, Davi Rubinho Ratero, Janine Contro, Keren Keinan-Adamsky, Ricardo Reis Soares, Gil Goobes, Leandro Martins, José G. Nery
      Vanadosilicates isostructural to ETS-10 and AM-6 microporous materials were synthesized hydrothermally using derivatives of cis- and trans-3,5-dimethyl-piperidine as organic structure directing agents (SDAs) and were subsequently tested as heterogeneous catalysts for the oxidehydration of glycerol to acrylic acid. The best performances were obtained with vanadosilicates prepared with 1,1,3,5-tetramethyl piperidinum cations, which were capable of converting 93.6% of glycerol to acrylic acid in one step, with 85.4% selectivity. Other important chemicals such as acrolein (3.8%), propanal (2.3%), acetaldehyde (3.2%), acetic acid (2.5%), and propionic acid (1.4%) were produced in smaller amounts. The results clearly indicated that these vanadosilicates are potential multifunctional catalysts capable of performing the oxidehydration of glycerol to acrylic acid in a single step. Spectroscopic data obtained from 51VMAS-NMR, UV-Vis, XPS, and Raman scattering analyses suggested that the selectivity of these vanadosilicates for the oxidative dehydration of glycerol to acrylic acid could be attributed to the capacity of the vanadium species for dynamic adoption of multiple oxidation states during the catalytic reaction.
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      PubDate: 2016-06-23T09:29:22Z
       
  • A helical peptide confined in metal-organic frameworks: Microscopic
           insight from molecular simulation
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): Zhongqiao Hu, Jianwen Jiang
      We report a molecular simulation study to investigate a helical peptide (β-adrenoceptor) confined in two metal-organic frameworks (MOFs) namely IRMOF-74-II and -III. Reversible structural transformation between the major (α-helix and 310-helix) and minor structures (bend, turn and coil) of the confined peptide is observed. In IRMOF-74-II, the peptide is over-confined and the helicity is lower compared to that in bulk water; however, the helicity is enhanced upon moderately confined in IRMOF-74-III. As attributed to the loss of conformational entropy, the thermal fluctuations of the peptide in both MOFs are smaller than in bulk water. The hydrophobic solvent-accessible surface area of the peptide, in contrast to the hydrophilic counterpart, is largely reduced upon confined in both MOFs because of the favorable interactions between hydrophobic residues and MOFs. This study provides microscopic insight into β-adrenoceptor peptide confined in MOFs and might be useful toward the rational design of nano-carriers for peptides and other biomolecules.
      Graphical abstract image

      PubDate: 2016-06-23T09:29:22Z
       
  • Enhanced nitrobenzene adsorption in aqueous solution by surface silylated
           MCM-41
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): Qingdong Qin, Yan Xu
      To improve the adsorption of nitrobenzene from aqueous solution, surface silylation of MCM-41 (hexagonal mesoporous silica) with trimethylchlorosilane was conducted. The silylated MCM-41 (CH3-MCM-41) was characterized by X-ray diffraction (XRD), transmission electron micrograph (TEM), N2 adsorption-desorption, Fourier transform infrared spectroscopy (FTIR), and thermogravimetric/differential thermalanalysis (TG/DTA) techniques. Adsorption of nitrobenzene onto CH3-MCM-41 was investigated with respect to contact time, initial nitrobenzene concentration, temperature, pH and ionic strength. The results indicated that surface modification of MCM-41 significantly enhanced its adsorption capacity for nitrobenzene. Adsorption isotherms were well described by Langmuir and Freudlich models. The maximum adsorption capacity of CH3-MCM-41 was 375.5 μmol/g, one order of magnitude higher than that of MCM-41 (25.8 μmol/g). Negative thermodynamic constant values (ΔG 0 < 0, ΔH 0 < 0 and ΔS 0 < 0) suggested that the adsorption reaction of nitrobenzene onto CH3-MCM-41 was thermodynamically favorable, spontaneous and exothermic under the examined conditions. Moreover, adsorption of nitrobenzene by CH3-MCM-41 was independent of pH within a range of 3.0–9.5. Increasing ionic strength can apparently enhance nitrobenzene adsorption by CH3-MCM-41. Compared to other adsorbents, CH3-MCM-41 showed a relatively higher adsorption capacity and shorter equilibrium time. Therefore, surface sylilated MCM-41 has a potential and promising application in the removal of nitrobenzene from water.
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      PubDate: 2016-06-23T09:29:22Z
       
  • New hydrothermal route for the synthesis of high purity nanoparticles of
           zeolite Y from kaolin and quartz
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): Jing-Quan Wang, Ya-Xi Huang, Yuanming Pan, Jin-Xiao Mi
      Reducing the activation temperature of kaolin for the synthesis of zeolites and other materials is a not only cost-effective but also green strategy. Hydrothermal alkaline activation (HAA) has been proposed as an effective technique for replacing the traditional high-temperature calcination route. However, one major obstacle to the exisiting HAA routes for the synthesis of zeolite Y is that the required addition of quartz leads to the formation of the acid insoluble analcime, resulting in an inefficient use of kaolin ores. In this study, a systematic investigation has been performed to develop a new HAA route for avoiding acid-insoluble aluminosilicates. Kaolin and quartz (KQ) as the sources for this new HAA route were then used to form hydroxycancrinite, which is readily dissolved in HCl solution and then neutralized by using the recycled alkali solution to form a uniform silica-alumina gel. The uniform gel promises the crystallization of zeolite Y with high purity and controllable morphologies and grain sizes, including nanoparticles. In particular, zeolite Y crystallized from the new HAA route depends on the SiO2/Al2O3 ratios of the starting materials but is independent of the types of the starting materials, i.e., irrespective of chemical reagents or raw minerals. Therefore, our work opens a new way for the synthesis of other mesoporous and macroporous materials e.g. aerogel, using low-cost natural kaolin and quartz in comparison with the conventional technique requiring expensive chemical reagents.
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      PubDate: 2016-06-18T14:02:17Z
       
  • Hybrid materials based on polyethylene and MCM-41 microparticles
           functionalized with silanes: Catalytic aspects of in situ polymerization,
           crystalline features and mechanical properties
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): M.L. Cerrada, A. Bento, E. Pérez, V. Lorenzo, J.P. Lourenço, M.R. Ribeiro
      New nanocomposites based on polyethylene have been prepared by in situ polymerization of ethylene in presence of mesoporous MCM-41. The polymerization reactions were performed using a zirconocene catalyst either under homogenous conditions or supported onto mesoporous MCM-41 particles, which are synthesized and decorated post-synthesis with two silanes before polymerization in order to promote an enhanced interfacial adhesion. The existence of polyethylene chains able to crystallize within the mesoporous channels in the resulting nanocomposites is figured out from the small endothermic process, located at around 80 °C, on heating calorimetric experiments, in addition to the main melting endotherm. These results indicate that polyethylene macrochains can grow up during polymerization either outside or inside the MCM-41 channels, these keeping their regular hexagonal arrangements. Mechanical response is observed to be dependent on the content in mesoporous MCM-41 and on the crystalline features of polyethylene. Accordingly, stiffness increases and deformability decreases in the nanocomposites as much as MCM-41 content is enlarged and polyethylene amount within channels is raised. Ultimate mechanical performance improves with MCM-41 incorporation without varying the final processing temperature.
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      PubDate: 2016-06-18T14:02:17Z
       
  • Desiccant capability of organic xerogels: Surface chemistry vs porous
           texture
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): Isabel D. Alonso-Buenaposada, Esther G. Calvo, M.A. Montes-Morán, J. Narciso, J. Angel Menéndez, Ana Arenillas
      Resorcinol-Formaldehyde xerogels are organic polymers that can be easily tailored to have specific properties. These materials are composed of carbon, hydrogen and oxygen, and have a surface that is very rich in oxygen functionalities, and is therefore very hydrophilic. Their most interesting feature is that they may have the same chemical composition but a different porous texture. Consequently, the influence of porous characteristics, such as pore volume, surface area or pore size can be easily assessed. In this work, a commonly used desiccant, silica gel, is compared with organic xerogels to determine their rate and capacity of water adsorption, and to evaluate the role of surface chemistry versus porous texture. It was found that organic xerogels showed a higher rate of moisture adsorption than silica gel. Pore structure also seems to play an important role in water adsorption capacity. The OX-10 sample, whose porosity was mainly composed of micro-mesoporosity displayed a water adsorption capacity two times greater than that of the silica gel, and three times higher than that of the totally macroporous xerogel OX-2100. The presence of feeder pores (mesopores) that facilitate the access to the hydrophilic surface was observed to be the key factor for a good desiccant behaviour. Neither the total pore volume nor the high surface area (i.e. high microporosity) of the desiccant sample, is as important as the mesopore structure.
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      PubDate: 2016-06-18T14:02:17Z
       
  • Synthesis of SAPO-18 with low acidic strength and its application in
           conversion of dimethylether to olefins
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): Yuichiro Hirota, Mayuka Yamada, Yoshiaki Uchida, Yasuhiro Sakamoto, Toshiyuki Yokoi, Norikazu Nishiyama
      SAPO-18 molecular sieve was synthesized by a dry gel conversion (DGC) and hydrothermal (HT) synthesis methods using methyltriethoxysilane as the only Si source (DGC-Me-SAPO-18 and HT-Me-SAPO-18). Their physicochemical and catalytic properties on dimethylether-to-olefin (DTO) reaction were compared with those of conventional SAPO-18 molecular sieves synthesized by a hydrothermal synthesis method (HT-SAPO-18). An NH3-TPD measurement revealed that the desorption peak position of Brønsted acid of the Me-SAPO-18 samples moved to lower temperature, indicating that Brønsted acidic strength of the Me-SAPO-18 samples was lower than that of the HT-SAPO-18 samples. The DME conversions and yields of light olefins over DGC-Me-SAPO-18 decreased at a slower rate than those of HT-SAPO-18. The decreased acidic strength and flake-like morphology of DGC-Me-SAPO-18 could retard the coke formation, leading to the prolonged catalytic lifetime.
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      PubDate: 2016-06-18T14:02:17Z
       
  • Steam-dealuminated, OSDA-free RHO and KFI-type zeolites as catalysts for
           the methanol-to-olefins reaction
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): Yuewei Ji, John Birmingham, Mark A. Deimund, Stephen K. Brand, Mark E. Davis
      RHO and KFI-type zeolites are synthesized in the absence of organic structure-directing agents (OSDAs), post-synthetically dealuminated via high temperature (600–800 °C) steam treatments, and evaluated as catalysts for converting methanol-to-light olefins (MTO). The proton forms of the as-made zeolites deactivate rapidly when tested for the MTO reaction (conducted at 400 °C and atmospheric pressure) due to their high aluminum content. Steam treatments lead to improvements in olefin selectivities and catalyst lifetimes with samples steamed at 600 °C giving the best combination of lifetime and olefin selectivity. Zeolite characterizations by 27Al NMR, 29Si NMR and argon physisorption indicate that the steam treatments extract framework aluminum, leading to reductions in the total number of Brønsted acid sites and the creation of mesopores that can facilitate transport of reactants. Poisoning of the acid sites external to the 8MR pores of the zeolites by treatments with trimethylphosphite results in longer catalyst lifetimes but do not affect the observed olefin selectivities, suggesting that olefins do not undergo secondary dimerization or methylation reactions at these sites.
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      PubDate: 2016-06-18T14:02:17Z
       
  • Adsorption of phosphates and phosphoric acid in zeolite clinoptilolite:
           Electronic structure study
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): Ellie L. Uzunova, Hans Mikosch
      Phosphate (H2PO4 − and HPO4 2−) and phosphoric acid adsorption in zeolite clinoptilolite was examined by electronic structure methods. The interactions of the anionic species with Lewis basic sites of the zeolite framework prevail over the interaction with extraframework cations (Na+, Ca2+, Mg2+) and the strength of the hydrogen bonds is quantitatively assessed by the shift of the νOH vibrational frequencies. Brønsted acid sites compete with cations in the binding of H2PO4 − and H3PO4. The B-channel of clinoptilolite, which is accessible via eight-member ring windows, provides more favorable coordination to phosphates and phosphoric acid in presence of cations. The dianions (HPO4 2−) reside only in channel B, coordinated to a divalent cation (Ca2+, Mg2+) and forming one hydrogen bond with a framework oxygen atom, acting as Lewis basic site. The monoanion H2PO4 − finds best coordination in channel B by adsorption at a Na+ cation and forming two hydrogen bonds. The negative charge of phosphate anions is efficiently delocalized over the framework oxygen atoms. The adsorbed phosphates and phosphoric acid acquire more polarized PO bonds compared to the free molecules and anions. In the presence of a Brønsted acid site, phosphoric acid is coordinated to the zeolite framework by four hydrogen bonds, the additional hydrogen being provided by the acid site. Hydrogen bond formation is essential for stronger binding of phosphoric acid and phosphate anions and the presence of Brønsted acid sites together with Lewis basic sites would increase zeolite adsorption capacities.
      Graphical abstract image

      PubDate: 2016-06-18T14:02:17Z
       
  • Doped TiO2 aerogels as alternative catalyst supports for proton exchange
           membrane fuel cells: A comparative study of Nb, V and Ta dopants
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): C. Beauger, L. Testut, S. Berthon-Fabry, F. Georgi, L. Guetaz
      Nb, Ta and V-doped TiO2 aerogels and xerogels have been synthesized as possible new alternatives to carbon blacks for Proton Exchange Membrane Fuel Cells catalyst supports. A comparative study of different dopants was realized in a single study. Nb, Ta and V showed different behaviors with respect to the final material structure and morphology, composition and electronic conductivity. They are all prone to surface segregation, to different extents. V-doped TiO2 apart, the rutile structure could only be obtained after calcination in a reducing atmosphere at 800 °C for Nb or Ta-doped TiO2. The electronic conductivity exhibited a maximum at 10 at.% for Nb and Ta, 5 at.% for V. Nb revealed to be the most appropriate dopant to increase the electronic conductivity of TiO2, followed by Ta and V. 4–5 orders of magnitude were gained after Nb doping for xerogels conductivity to reach almost 0.1 S cm−1. The role of point defects was discussed to account for phase transition and evolution of conductivity.
      Graphical abstract image

      PubDate: 2016-06-18T14:02:17Z
       
  • The effect of zinc and copper in gold catalysts supported on MCF cellular
           foams on surface properties and catalytic activity in methanol oxidation
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): Iveta Bilkova, Izabela Sobczak, Piotr Decyk, Maria Ziolek, James E. Whitten
      MCF (Mesostructured Cellular Foams) and Zn/MCF were used as supports for gold and copper. The effect of zinc and copper on the surface properties, activity and selectivity of gold catalysts in the methanol oxidation was studied. The catalysts were characterized in detail by XRD, TEM, UV–Vis, XPS, ESR and FTIR-NO. The results showed that zinc oxide species play the role of a structural promoter which protects against agglomeration of gold species and an electronic promoter, decreasing reducibility of copper cations by the strong copper-zinc interaction. These interactions result in the incorporation of copper into the crystal structure of zinc oxide and lead to changes in the surrounding of gold in bimetallic (Au-Cu) catalysts compared to materials without zinc. The composition of the catalysts determines their activity and selectivity in methanol oxidation. Bimetallic (Au-Cu) catalysts, irrespective of the nature of the support (MCF vs Zn/MCF), are much more active than monometallic (Au) samples as a result of synergistic interactions between Au and Cu species. The samples containing zinc are highly selective to formaldehyde due to Au-Zn and/or Cu-Zn interaction, which weakens the adsorption of formaldehyde.
      Graphical abstract image

      PubDate: 2016-06-18T14:02:17Z
       
  • The effect of structure modifying agents in the SBA-15 for its application
           in the biomolecules adsorption
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): Sandra M.L. Santos, Juan A. Cecilia, Enrique Vilarrasa-García, Ivanildo J. Silva Junior, Enrique Rodríguez-Castellón, Diana C.S. Azevedo
      The traditional mesoporous silica (SBA-15) was synthesized by hydrothermal route. The swelling agents 1,3,5-trymethylbenzene (TMB) and heptane were used to expand the pore size and fluoride (NH4F) was used to modify the length of the pores, leading to porous silicas with different textural properties. The adsorbents, identified as SBA-15 (S), SBA-15 (S1) (TMB), SBA-15 (S2) (TMB and NH4F) and SBA-15 (S3) (NH4F and heptane), were characterized regarding their texture, mesoscopic ordering and chemical surface and finally their adsorption capacity was evaluated using three model biomolecules (Bovine Serum Albumin – BSA, Lysozyme – LYS and Cellulase – CEL). Adsorption behavior of BSA, LYS and CEL onto these SBA-15 samples was investigated by batch experiments at 25 °C. Highest biomolecule uptake obtained for S2 and S3 were attributed to the larger pore diameter, shorter channel length and the formation of interparticle voids, which provides easier access of these biomolecules to the surface of the adsorbent and minimized the diffusion problems. All cellulase adsorption isotherms followed Henry’s Law. The adsorption capacity of cellulase in S2 was 250 mg/g for a liquid-phase equilibrium concentration of 6 mg/mL, while BSA and LYS adsorption isotherms were well fit by the Langmuir model and the maximum adsorption capacities were 581 and 786 mg/g, respectively.
      Graphical abstract image

      PubDate: 2016-06-14T14:22:29Z
       
  • LTA zeolite monoliths with hierarchical trimodal porosity as highly
           efficient microreactors for strontium capture in continuous flow
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): Bilel Said, Agnes Grandjean, Yves Barre, Franck Tancret, Francois Fajula, Anne Galarneau
      LTA zeolite monoliths (6 mm diameter, 3 cm length) featuring a hierarchical trimodal network of micro-/meso- and macropores (obtained by either controlling the nucleation step of LTA crystallization into nanocrystals or by creating mesopores into micronic crystals by using organosilane surfactant) were used for strontium capture in aqueous medium. LTA monoliths were compared to other LTA zeolite architectures: LTA microcrystals, commercial LTA beads and bimodal micro-/macroporous LTA zeolite monoliths. In batch mode, the presence of mesopores allowed to increase remarkably by a factor 15 the diffusion of ions, whereas macropores had no influence on ions transport. In flow mode, only LTA monoliths featuring flow-through macropores proved suitable as microreactors. The trimodal LTA monoliths were 1000 times more efficient than packed-beds of LTA beads, and 4 times than bimodal (micro-/macroporous) LTA monoliths due to higher rates of diffusion. Trimodal LTA monoliths were able to treat efficiently 4 L of Sr2+ solution (10 mg L−1) with 1 mL of material at a flow rate of 0.5 mL min−1 (or 1 m h−1); ie. 4200 bed volumes (BV) were efficiently treated at a flow rate of 34 BV h−1, with no Sr2+ detectable by ionic-chromatography in the effluent. This result highlights the fact that the multiscale pore architecture engineering of an adsorbent is crucial for process intensification: macropores allow uniform mass transport of solutions with low pressure drop while the generation of mesopores in zeolites leads to faster ionic transport and more efficient crystal use in cation-exchange processes, both in batch and flow modes.
      Graphical abstract image

      PubDate: 2016-06-14T14:22:29Z
       
  • Synthesis, characterization of magnetic chitosan/active charcoal composite
           and using at the adsorption of methylene blue and reactive blue4
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): Hatice Karaer, İsmet Kaya
      In this study, a chitosan/activated charcoal (or carbon) (CTN/AC-Fe3O4) composite was obtained in one step, characterized several techniques such as by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, dynamic light scattering, Brunauer-Emmet-Teller, thermogravimetric analysis/differential thermal analysis and differential scanning calorimetry techniques. The sorption the composite were investigated as kinetically and thermodynamically for removal of methylene blue (MB) and reactive blue4 (RB4) from aqueous solution. Effects of several parameters, such as initial temperature and initial concentration on removal of MB and RB4 from aqueous solution by the composite were investigated as a function of contact time. Maximum adsorption capacity (Qmax) was found to be 500 mg g−1 at and 250 mg g−1 at 318 K for MB, 298 K for RB4 respectively. Also, thermodynamic parameters such as ΔH0, ΔG0 and ΔS0 were calculated by Langmuir adsorption isotherm model. Negative Gibbs free energy (ΔG0) implies that the adsorption is spontaneous and positive adsorption enthalpy (ΔH0) demonstrates the process is endothermic for MB while negative adsorption enthalpy (ΔH0) demonstrates the process is exothermic for RB4, respectively.
      Graphical abstract image

      PubDate: 2016-06-14T14:22:29Z
       
  • Alkali-activation of spent fluid cracking catalysts for CO2 capture
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): Jefferson S. Silva, Raimundo Medeiros de Jesus-Neto, Raildo A. Fiuza, Jardel Pereira Gonçalves, Artur J.S. Mascarenhas, Heloysa M.C. Andrade
      Residual USY phase in waste fluid craking catalysts were used as zeolitic building blocks to prepare zeolite materials by activation with NaOH solutions and the prepared materials were characterized (XRD, EDX, SEM, FTIR and N2 physisorption) and further tested as CO2 adsorbents. The resulting materials contained zeolites ZK-14 (CHA), P-1 (GIS), ZK-4 (LTA), Analcime (ANA) and γ-alumina, but the phase distribution mainly depended on the Na/Si atom ratio and reaction temperature. High micropore surface area and the composition of the zeolitic phases in the composite were the main characteristic controlling the CO2 uptakes and high uptakes were achieved by the samples with increasingly high ZK-14 (CHA) contents.
      Graphical abstract image

      PubDate: 2016-06-14T14:22:29Z
       
  • UHMWPE/SBA-15 nanocomposites synthesized by in situ polymerization
    • Abstract: Publication date: 15 September 2016
      Source:Microporous and Mesoporous Materials, Volume 232
      Author(s): Ana E. Ferreira, Maria L. Cerrada, Ernesto Pérez, Vicente Lorenzo, Henri Cramail, João P. Lourenço, M. Rosário Ribeiro
      Different nanocomposites have been attained by in situ polymerization based on ultra-high molecular weight polyethylene (UHMWPE) and mesoporous SBA-15, this silica being used for immobilization of the FI catalyst bis [N-(3-tert-butylsalicylidene)-2,3,4,5,6-pentafluoroanilinato] titanium (IV) dichloride and as filler as well. Two distinct approaches have been selected for supporting the FI catalyst on the SBA-15 prior polymerization. A study on polymerization activity of this catalyst has been performed under homogenous conditions and upon heterogenization. A study of the effect of presence of mesoporous particles and of the immobilization method is also carried out. Moreover, the thermal characterization, phase transitions and mechanical response of some pristine UHMWPEs and UHMWPE/SBA-15 materials have been carried out. Relationships with variations on molar mass, impregnation method of catalyst and final SBA-15 content have been established.
      Graphical abstract image

      PubDate: 2016-06-14T14:22:29Z
       
 
 
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