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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  [2970 journals]
  • Editorial Board
    • Abstract: Publication date: 1 September 2016
      Source:Microporous and Mesoporous Materials, Volume 231




      PubDate: 2016-06-23T09:29:22Z
       
  • Inside back cover - Contents (continued from back cover)
    • Abstract: Publication date: 1 September 2016
      Source:Microporous and Mesoporous Materials, Volume 231




      PubDate: 2016-06-23T09:29:22Z
       
  • Outside back cover (contents)
    • 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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      PubDate: 2016-06-18T14:02:17Z
       
  • Low field 1H NMR characterization of mesoporous silica MCM-41 and SBA-15
           filled with different amount of water
    • Abstract: Publication date: 1 September 2016
      Source:Microporous and Mesoporous Materials, Volume 231
      Author(s): A.T. Krzyżak, I. Habina
      The low field 1H NMR characterization of pure mesoporous silica materials – MCM-41 and SBA-15 as a function of water content is presented. The values of surface relaxivities for both materials were estimated in order to compare pore size distributions obtained from relaxation spectra and N2 adsorption measurements. This comparison led to differentiation between contributions from ‘inner-bulk’ water molecules in pores and these from the surface. The T1/T2 ratio reflecting the strength of interaction between water molecules and the mesoporous silica surface was confirmed to be higher for SBA-15. Measurements for a mesopore surface partially covered by water provided quantitative information on the hydroxylation rate.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
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      PubDate: 2016-06-18T14:02:17Z
       
  • Understanding the role of nickel on the hydrogen storage capacity of
           Ni/MCM-41 materials
    • Abstract: Publication date: 1 September 2016
      Source:Microporous and Mesoporous Materials, Volume 231
      Author(s): P.M. Carraro, A.A. García Blanco, F.A. Soria, G. Lener, K. Sapag, G.A. Eimer, M.I. Oliva
      In this study, we prepared MCM-41 mesoporous materials modified with different Ni contents, as promising materials for hydrogen storage. We focused on the role of dispersed nickel as a way of promoting the interaction with hydrogen as an alternative to improve hydrogen storage materials. In addition, the reducibility of Ni/MCM-41 materials was studied, and the hydrogen adsorption in the reduced materials was evaluated, in order to compare the behaviour of reduced and unreduced Ni/MCM-41 materials in hydrogen storage at 77 and 293 K. Hydrogen adsorption isotherms were measured at 77 K and 293 K, and at low and high-pressure conditions respectively. The results obtained show that the amount of hydrogen stored was highly enhanced by the dispersion of small amounts of Ni nanoparticles both at 77 and 293 K. Experimental techniques such as TPR, XPS, N2 adsorption-desorption and computational methods (DFT) were used in order to interpret the results and contribute to the understanding of hydrogen adsorption on Ni/MCM-41 materials.
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      PubDate: 2016-06-14T14:22:29Z
       
  • Synthesis, characterization and catalytic studies by zeolite encapsulated
           hexaazamacrocyclic complexes of nickel(II) and copper(II)
    • Abstract: Publication date: 1 September 2016
      Source:Microporous and Mesoporous Materials, Volume 231
      Author(s): G. Ramanjaneya Reddy, S. Balasubramanian
      The nickel(II) and copper(II) complexes of the 16-membered 1,3,6,9,11,14-hexaazatricyclo[12.2.1.16,9]octadecane (THA) were synthesized by in situ one-pot template method. The nickel(II)THA and copper(II)THA complexes are represented as NTHA and CTHA respectively. The encapsulation of free complexes (FC) (i.e. NTHA and CTHA) in the cavities of zeolite-Y was achieved by ship-in-bottle method. The zeolite encapsulated metal complexes (ZEMC) are represented as NTHAY and CTHAY. The retention of the free complex with ZEMC was investigated by spectral, thermal, sorption and microscopic techniques (i.e., FTIR, ESI-mass, DRS/UV–visible, XPS, TGA, XRD, nitrogen adsorption isotherm, SEM and TEM). The NTHA, CTHA, NTHAY and CTHAY were employed as catalysts for the oxidation of Reactive Red 198 (RR) and Phenol Red (PR) dyes under UV irradiation. The ZEMC exhibits higher catalytic activity for the degradation of dyes, when compared to that of FC. The reusable photocatalysts show comparable activity to that of the fresh catalysts.
      Graphical abstract image

      PubDate: 2016-06-14T14:22:29Z
       
  • A 4-fold interpenetrated diamondoid metal-organic framework with large
           channels exhibiting solvent sorption properties and high iodine capture
    • Abstract: Publication date: 1 September 2016
      Source:Microporous and Mesoporous Materials, Volume 231
      Author(s): Gift Mehlana, Gaëlle Ramon, Susan A. Bourne
      The characterisation of a 4-fold interpenetrated diamondoid metal-organic framework (MOF) {[Ni4(44pba)8]·sol}n, (1) (44pba = 4-(4-pyridyl)benzoate) is reported. The compound was prepared from Ni(II) and 44pba under solvothermal conditions. When activated to give 1d, the compound absorbs a wide range of solvents which is accompanied by a visible colour change. Sorption of water triggers an irreversible phase transformation, while adsorption of methanol, ethanol, benzene, dimethylformamide and cyclohexanone does not affect the structural integrity of the framework as revealed by powder X-ray diffraction studies. Apart from ethanol, the uptake of polar protic solvents gave rise to an increase in the energy difference between the asymmetric and symmetric carboxylate stretches as confirmed by infrared studies. We attributed this to a change in the binding mode of the carboxylates from chelating to monodentate. The activated phase (1d) was found to absorb high levels of iodine into its channels in comparison to other reported MOFs. This is due to the high porosity of the network compound in which aromatic walls allow for the interaction of iodine molecules with the framework walls.
      Graphical abstract image

      PubDate: 2016-06-14T14:22:29Z
       
  • Controlled pore size of 3D mesoporous Cu-Ce based catalysts and influence
           of surface textures on the CO catalytic oxidation
    • Abstract: Publication date: 1 September 2016
      Source:Microporous and Mesoporous Materials, Volume 231
      Author(s): Liyan Li, Weiliang Han, Jiyi Zhang, Gongxuan Lu, Zhicheng Tang
      In this paper, 3D Cu-Ce-Ox catalysts with controllable pore diameters were rationally designed and synthesized by a facile hard-template method. By controlling the hydrothermal synthesis time, mesoporous silica KIT-6 with different pores were prepared. Then, the 3D Cu-Ce-Ox catalysts were synthesized by nano-replication technology with KIT-6 as hard template. These catalysts expressed 3D pore structure, possessed higher pore volume and large pores, and owned more surface active sites, which were helpful for CO oxidation. When the synthesis time of KIT-6 was 24 h, this catalyst showed the highest catalytic activity. The reason was due to its relatively stronger redox ability and surface activity species. More Ce3+, Cu+ and chemical adsorbed oxygen concentration was very useful in achieving the highest catalytic performance.
      Graphical abstract image

      PubDate: 2016-06-14T14:22:29Z
       
  • Preparation of large pore volume γ-alumina and its performance as
           catalyst support in phenol hydroxylation
    • Abstract: Publication date: 1 September 2016
      Source:Microporous and Mesoporous Materials, Volume 231
      Author(s): Jing Xu, Abdul-Rauf Ibrahim, Xiaohui Hu, Yanzhen Hong, Yuzhong Su, Hongtao Wang, Jun Li
      Alumina was synthesized from Al(NO3)3, AlCl3 and Al3(SO4)2 with NaOH, and from NaAlO2 with HNO3 by addition of acidic solution to alkaline solution with a syringe pump. The as-produced Al2O3 precursors were supercritically dried and calcined at 500 °C to obtain mesoporous γ-alumina material. Results showed that all the inorganic aluminum salts could be used to synthesize high pore volume γ-alumina by controlling the precursor addition rate at room temperature and supercritical CO2 drying. However, the γ-alumina with the largest pore volume (5.4 cm3/g), BET surface area (423.7 m2/g) and pore size (37.8 nm) was obtained using Al(NO3)3 and NaOH. This γ-alumina was further used as a support for Fe-based catalyst with hydrogen peroxide to produce hydroquinone and catechol in the phenol hydroxylation reaction in 30 min at 80 °C. The conversion of phenol was 53.4% whereas the selectivity to dihydroxybenzenes-DHBs (hydroquinone-HQ and catechol-CAT) was as high as 96.2%, revealing that the larger pore volume takes effect in the γ-alumina as support for the Fe-based catalyst in the hydroxylation reaction, and that the γ-alumina may be a good candidate as the support for other important catalysts such as those used in the petroleum refining industry.
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      PubDate: 2016-06-14T14:22:29Z
       
  • Development of response surface methodology for optimization of phenol and
           p-chlorophenol adsorption on magnetic recoverable carbon
    • Abstract: Publication date: 1 September 2016
      Source:Microporous and Mesoporous Materials, Volume 231
      Author(s): Babak Kakavandi, Mahsa Jahangiri-rad, Mohammad Rafiee, Amirhosein Ramazanpour Esfahani, Ali Akbar Babaei
      The powdered activated carbon impregnated with Fe3O4 magnetic nanoparticles (MNPs) was synthesized by a facile in situ chemical co-precipitation method. The response surface methodology (RSM) with central composite design (CCD) was used to investigate the adsorption properties of phenol and p-chlorophenol (PCP) onto as-synthesized composite. The RSM was also applied to study the main and interactive effects of the parameters (pH, adsorbent dosage, contact time, and initial pollutant concentration) investigated, as well as to obtain the optimum operating conditions for this novel adsorbent. Magnetic powdered activated carbon (MPAC) showed an excellent magnetic response to the magnetic field and was easily separated from the solution. Moreover, the RSM model obtained (R2 > 0.98) revealed a satisfactory correlation between the experimental results and predicted values of phenol and PCP adsorption. The adsorbent dose was indicated as having the strongest positive influence on adsorption. The identified optimum conditions of adsorption was 6, 118 min, 1.6 g/L and 200 mg/L for pH, contact time, adsorbent dose, and initial phenol and PCP concentration, respectively. The adsorption kinetics fitted well with pseudo-second-order model and the adsorption capacity of phenol and PCP on MPAC inferred from the Langmuir model was 123.45 and 120.48 mg/g, respectively, at 20 °C. In addition, the adsorption activity of MPAC was preserved effectively even after five successive cycles of use owing to its good stability. The thermodynamic parameters indicated that the adsorption of phenol and PCP onto modified PAC was an exothermic and spontaneous process.
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      PubDate: 2016-06-14T14:22:29Z
       
  • Synthesis of mixed ligand and pillared paddlewheel MOFs using waste
           polyethylene terephthalate material as sustainable ligand source
    • Abstract: Publication date: 1 September 2016
      Source:Microporous and Mesoporous Materials, Volume 231
      Author(s): Duraisamy Senthil Raja, Chih-Chiung Pan, Chia-Wei Chen, Yu-Hao Kang, Jiun-Jen Chen, Chia-Her Lin
      A series of five isostructural pillared-paddlewheel MOFs, [M2(BDC)2(DABCO)] (1–5), (where M = Fe(II) (1), Co(II) (2), Ni(II) (3), Cu(II) (4) and Zn(II) (5); BDC = benzene-1,4-dicarboxylate; and DABCO = 1,4-diazabicyclo[2.2.2]octane) have been synthesized by using waste polyethylene terephthalate (PET) material as a direct BDC source. The optimal reaction condition has been achieved for all the MOFs with 100% depolymerization of waste PET material in the reaction. The synthesized MOFs have been characterized using powder X-ray diffraction, scanning electron microscopy, thermal gravimetric analyses, and N2 gas sorption measurements. Results showed that the porous MOFs have similar properties of their corresponding literature reports.
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      PubDate: 2016-06-14T14:22:29Z
       
  • Dry-gel synthesis of shaped transition-metal-doped M-MFI
           (M = Ti, Fe, Cr, Ni) zeolites by using metal-occluded zeolite
           seed sol as a directing agent
    • Abstract: Publication date: 1 September 2016
      Source:Microporous and Mesoporous Materials, Volume 231
      Author(s): Hao Zhang, Yan Fei Fan, Yi Hong Huan, Ming Bo Yue
      Shaped transition-metal-doped M-MFI zeolites were prepared using a rapid dry-gel conversion technique from shaped extrudates by using a metal-occluded zeolite seed sol as a directing agent. The metal (Ti, Fe, Cr, Ni)-occluded zeolites seed sols were prepared at a high tetrapropylammonium hydroxide (TPAOH)/SiO2 molar ratio or with the addition of triethanolamine to keep a good dispersion of the transition metal in the seed sols. The silica gel and zeolites seed sols were mixed well and extruded into cylindrical-shaped extrudates with a diameter of 2 mm with the aid of polydimethylsiloxane (PDMS). The PDMS not only facilities the extrusion of the precursor but also increases the compressive strength of the obtained shaped zeolites. The metal-occluded seed sol promoted the distribution of the metal and provided crystal nuclei for rapid crystallization. In this method, the total molar ratio of TPAOH/SiO2 decreased to 0.1–0.175, which lowers the cost of preparing the zeolites. The morphology and textural properties were characterized by scanning electron microscopy and nitrogen sorption isotherms. The obtained shaped M-MFI zeolites comprised nanosized crystals (50–200 nm) and exhibited a good dispersion of the metals in the framework of the zeolite.
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      PubDate: 2016-06-14T14:22:29Z
       
  • The synthesis and fluorescence detection properties of benzoquinone-based
           conjugated microporous/mesoporous polymers
    • Abstract: Publication date: 1 September 2016
      Source:Microporous and Mesoporous Materials, Volume 231
      Author(s): Tong-Mou Geng, Deng-Kun Li, Zong-Ming Zhu, Ye-Bin Guan, Yu Wang
      The benzoquinone-based conjugated microporous/mesoporous polymers were synthesized through Sonogashira–Hagihara cross-coupling with tetrabromo-1,4-benzoquinone (TBrBQ) and 1,4-diethynylbenzene (DEB) by both solution polymerization (DBQP) and miniemulsion polymerization (DBQN). The Brunauer–Emmett–Teller (BET) surface areas of these polymers were 356 and 25 m2 g−1 and pore average diameter were concentrated at around 2.12 and 3.84 nm for DBQP and DBQN, respectively. The two dimensional π-conjugated polymer frameworks could be combined with permanent microporous/mesoporous, luminescent properties and abundant oxygen atoms in the skeleton. Fluorescence studies found that both DBQP and DPQN could be utilized as fluorescent chemosensors for picronitric acid (PA) in acetone suspension.
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      PubDate: 2016-06-14T14:22:29Z
       
  • New method for introducing mesopores into carbon microhoneycombs using
           dextran
    • Abstract: Publication date: 1 September 2016
      Source:Microporous and Mesoporous Materials, Volume 231
      Author(s): Shinichiroh Iwamura, Kohei Kitano, Isao Ogino, Shin R. Mukai
      Carbon microhoneycombs (CMHs), which can be prepared from a resorcinol–formaldehyde (RF) hydrogel using ice crystals as a template, are attractive materials for industrial applications such as solid catalysts and adsorbents in flow system reactors. For such applications, pores in a material are important for mass transfer, but the mesopore volumes of CMHs are smaller than that of typical RF-derived carbons because ice crystals compress RF gels during freezing, and mesopores partly collapse. The introduction of mesopores into CMHs requires an additional step such as HCl treatment in the preparation process, and this increases the preparation time. In this work, we developed a convenient method for introducing mesopores into CMHs, in which dextran was added to the initial RF solution. This simple step increased the mesopore volume from 0.015 to 0.191 cm3/g. We investigated the porous structure of the sample at each step in the preparation, and found that dextran protected the porous structure of the RF hydrogel from growth of ice crystals, enabling mesopore introduction. A combination of dextran addition and HCl treatment further increased the mesopore volume to 0.753 cm3/g; this cannot be achieved using HCl treatment alone. This may be because the HCl solution can diffuse through the mesopores introduced by dextran addition, and this promotes pore formation.
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      PubDate: 2016-06-14T14:22:29Z
       
  • Coordination polymers with mixed 1,
           3-bis(1-imidazolyl)-5-(imidazol-1-ylmethyl)benzene and multicarboxylate
           ligands: Synthesis, structure and property
    • Abstract: Publication date: 1 September 2016
      Source:Microporous and Mesoporous Materials, Volume 231
      Author(s): Ye Deng, Yue Zhao, Xiu-Du Zhang, Yan-Shang Kang, Wei-Yin Sun
      Five new coordination polymers [Zn3(biimb)2(BPT)2]·4DMF·2.5H2O (1), [Zn(biimb)(NDC)]·1.5H2O (2), [Zn(biimb)(NDC)]·3DMF (3), [Cd(biimb)(NDC)0.5Cl]·3H2O (4) and [Cd3(biimb)2(BPDC)3(H2O)4]·4H2O (5) [biimb = 1,3-bis(1-imidazolyl)-5-(imidazol-1-ylmethyl)benzene, H3BPT = biphenyl-3,4′,5-tricarboxylic acid, H2NDC = 2,6-naphthalenedicarboxylic acid, H2BPDC = 4,4′-biphenyldicarboxylic acid, DMF = N,N-dimethylformamide] were synthesized by hydro/solvothermal reactions and characterized by elemental, thermogravimetric analyses, IR, powder and single crystal X-ray diffractions. Complex 1 is a (3,3,4,4)-connected 4-nodal 3D framework. The linkage of Zn(II), biimb and NDC2− makes a 2D network structure of 2, in which biimb acts as a bidentate ligand, while in 3, the biimb ligands display as tridentate and connect Zn(II) to compose 2D networks, which are further linked together by NDC2− to generate 3D structure of 3. 4 is a pillared-layer 3D net containing [Cd(biimb)Cl]+ layers and NDC2− pillars. 5 is an interesting 3-fold interpenetrating 3D net. Photoluminescence and gas adsorption properties of the complexes were investigated.
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      PubDate: 2016-06-14T14:22:29Z
       
  • 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.
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      PubDate: 2016-06-14T14:22:29Z
       
  • One pot microwave synthesis of MCM-41/Cu based MOF composite with improved
           CO2 adsorption and selectivity
    • Abstract: Publication date: 1 September 2016
      Source:Microporous and Mesoporous Materials, Volume 231
      Author(s): Nesa Esmaeilian Tari, Azadeh Tadjarodi, Javad Tamnanloo, Shohreh Fatemi
      The MCM-41@ Cu(BDC) composite material was synthesized via a facile and fast microwave method. MCM-41 was used as matrix which composed by Cu(BDC) MOF. The effect of molar ratio of the metal salt to MCM-41 substrate was investigated. The synthesized composites were characterized by means of FTIR analysis, X-ray diffraction (XRD), Scanning electron microscopy (SEM), Thermogravimetric analysis (TGA), N2 adsorption-desorption isotherms and Transmission electron microscopy (TEM). The adsorption capacities of the samples were measured by a volumetric method at ambient temperature and the pressure range of 1–25 bar. The composite material with molar ratio of 1:8 (metal ion: MCM-41) demonstrated a 30% increase in CO2/CH4 selectivity and 20% increase in adsorption capacity compared to MCM-41. The stability investigation of the composite in consecutive adsorption-desorption cycles showed no significant loss in adsorption capacity.
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      PubDate: 2016-06-14T14:22:29Z
       
  • Hierarchically macro/mesoporous silica sphere: A high efficient carrier
           for enzyme immobilization
    • Abstract: Publication date: 1 September 2016
      Source:Microporous and Mesoporous Materials, Volume 231
      Author(s): Jing Li, Lu-Shuang Li, Li Xu
      In the present study, a hierarchically macro/mesoporous silica was fabricated, characterized and evaluated as a potential carrier for enzyme immobilization. The silica contained bicontinuous structure of skeletons and macropores, which were interwoven, thus forming a highly porous network. This unique structure rendered the silica as an efficient carrier for many applications, especially in which fast mass transfer was required. Herein, it was used as the carrier to immobilize catalase (CAT) for the catalytic purpose. The CAT loading amount can reach 285 mg/g (enzyme/carrier). As expected, the catalytic efficiency/activity of the immobilized catalase (IMCAT) was quite high (Km value of 176.54 mM), which was comparable with that of the free CAT (Km value of 169.78 mM). Additionally, the temperature and pH stability of IMCAT was almost the same as free CAT. However, it is noteworthy that, the IMCAT can be retrieved for repetitive usage. After 20 cycles, IMCAT still possessed relative activity more than 50%. The proposed hierarchically macro/mesoporous silica was demonstrated to be a promising carrier for enzyme immobilization and application, with high loading amount, excellent stability and desirable repeatability.
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      PubDate: 2016-06-14T14:22:29Z
       
  • Molecular simulation studies of hydrogen enriched methane (HEM) storage in
           Covalent Organic Frameworks
    • Abstract: Publication date: 1 September 2016
      Source:Microporous and Mesoporous Materials, Volume 231
      Author(s): Jiawei Liao, A. Ozgur Yazaydin, Siyuan Yang, Fan Li, Lifeng Ding
      Instead of separating hydrogen and methane mixture, such as synthetic gas, to obtain pure hydrogen and methane as clean fuel, hydrogen enriched methane (abbreviated as HEM) storage in 33 different Covalent Organic Frameworks (COFs) were studied for the first time near ambient temperatures using Grand Canonical Monte Carlo (GCMC) simulation. The use of HEM for on-board combustion engine is also known to be able to improve combustion performance as well as decrease noxious emissions. HEM adsorption performance in the COFs was mainly evaluated from three different aspects: volumetric energy density of combustion of stored HEM, gravimetric energy density of combustion of stored HEM and hydrogen selectivity. Several properties of the COFs, such as surface area, porosity, pore size were calculated for establishing the correlation with the HEM adsorption performance. The effect of temperature, initial hydrogen/methane bulk composition and hydrogen and methane/hydrogen’s heat of adsorption (HOA) in COFs on the performance of HEM adsorption were also investigated. Our work suggested there exists a complex interplay of the properties of the COFs, temperature and bulk composition which influence the energy density of the adsorbed HEM as well as methane and hydrogen ratio in the adsorbed phase.
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      PubDate: 2016-06-14T14:22:29Z
       
  • Mesoporous NiCo based nanowire arrays supported on three-dimensional
           N-doped carbon foams as non-noble catalysts for efficient oxygen reduction
           reaction
    • Abstract: Publication date: 1 September 2016
      Source:Microporous and Mesoporous Materials, Volume 231
      Author(s): Xiaoyu Wu, Songmei Li, Bo Wang, Jianhua Liu, Mei Yu
      Homologous NiCo based mesoporous nanowire arrays, involving nickel cobalt oxide (NiCo2O4) and nickel cobalt sulfide (NiCo2S4), are successfully grown on three-dimensional (3D) nitrogen-doped carbon foam (NDCF) via a facile hydrothermal reaction followed by annealing and sulfurization treatment, respectively. The NiCo2O4 nanowires in the obtained NiCo2O4/NDCF composites are composed of numerous small nanoparticles with the presence of mesopores, while the NiCo2S4 nanowires of NiCo2S4/NDCF composites exhibit unique hollow structures with mesoporous walls. When served as non-noble catalysts for oxygen reduction reaction (ORR), the homologous NiCo2O4/NDCF and NiCo2S4/NDCF composites exhibit a comparable catalytic activity with a four-electron pathway, superior selectively and methanol tolerance over commercial Pt/C catalyst. Especially, the NiCo2S4/NDCF composites possess much higher stability than the Pt/C catalyst in alkaline electrolyte, thus holding great promise in practical application. The impressive performance may originate from the hollow nanowire morphology and the unique mesoporous structure which provide a high surface density of catalytic active sites exposed to oxygen molecules and facilitate the efficient transport of reactant species. Meanwhile, the introduced NDCF with enhanced catalytic activity from the incorporation of the N element generates synergistic effect with NiCo2O4 and NiCo2S4, and enhances their conductivities, therefore playing a significant role in improving their catalytic performance.
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      PubDate: 2016-06-14T14:22:29Z
       
  • TiO2/titanate composite nanorod obtained from various alkali solutions as
           CO2 sorbents from exhaust gases
    • Abstract: Publication date: 1 September 2016
      Source:Microporous and Mesoporous Materials, Volume 231
      Author(s): Joanna Kapica-Kozar, Ewa Piróg, Rafal J. Wrobel, Sylwia Mozia, Ewelina Kusiak-Nejman, Antoni W. Morawski, Urszula Narkiewicz, Beata Michalkiewicz
      A series of TiO2/titanate composite nanorods-based CO2 adsorbents with a high capture efficiency was prepared through hydrothermal method, followed by annealing at 350 °C in air, and subsequent functionalization with tetraethylenepentamine (TEPA). The CO2 adsorption performance of the prepared samples was measured using TGA. Firstly, it was found that the increase of adsorption capacity was related to textural properties of tested nanomaterials (higher for nanorod composites than for starting TiO2 and P25 powders). Secondly, the TiO2/titanate composite nanorods, obtained in the presence of KOH, exhibited higher adsorption capacity for CO2 in comparison with the NaOH-modified samples due to the increase of the SBET, total mesopore volume. Moreover, the nanorod composites obtained in presence of KOH exhibited a high content of titanate. TEPA-modified TiO2/titanate composite nanorods (P25-NRsK-TEPA) showed the highest adsorption capacity of 3.02 mmol CO2/g. This result could be indirectly related to high surface area responsible for maximizing exposure of its NH2 functional groups for interaction with CO2 and the higher pore volume, which may reduce the conglomerates of the impregnated TEPA within the pores, leading to better distribution of amine and consequently increasing the CO2 adsorption capacity. The results also indicates that TEPA-titanate interaction enhances CO2 capacity compared to TEPA-anatase materials. That material not only displayed high CO2 adsorption capacity but also exhibited a relatively stable performance during 6 consecutive adsorption-desorption cycles.
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      PubDate: 2016-06-14T14:22:29Z
       
  • Preparation and characterization of ZnO/nanoclinoptilolite as a new
           nanocomposite and studying its catalytic performance in the synthesis of
           2-aminothiophenes via Gewald reaction
    • Abstract: Publication date: 1 September 2016
      Source:Microporous and Mesoporous Materials, Volume 231
      Author(s): Farzad Javadi, Reza Tayebee
      The nanocomposite ZnO/nanoclinoptilolite (ZnO/NCP) was prepared and performed as an efficient heterogeneous catalyst in the synthesis of 2-aminotiophene derivatives by Gewald reaction. The nanocomposite was prepared through impregnation of the nanoclinoptilolite (NCP) surface with zinc chloride solution through Zn2+ ion exchange, followed by calcination at 500 °C for 24 h. The synthesized nanocomposite was characterized by XRD, SEM, FESEM, FT-IR, ICP, and nitrogen adsorption/desorption isotherm. The obtained catalytic assays demonstrated that the catalytic activity of ZnO/NCP nanocomposite was increased with enhancing the amount of ZnO. Moreover, the prepared nanocomposite showed very good stability and reusability in the titled synthetic method under aerobic and mild conditions.
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      PubDate: 2016-06-14T14:22:29Z
       
  • Stable and efficient aromatic yield from methanol over alkali treated
           hierarchical Zn-containing HZSM-5 zeolites
    • Abstract: Publication date: 1 September 2016
      Source:Microporous and Mesoporous Materials, Volume 231
      Author(s): Chengguang Yang, Minghuang Qiu, Shengwei Hu, Xinqing Chen, Gaofeng Zeng, Ziyu Liu, Yuhan Sun
      Fast deactivation of catalyst is the main problem in methanol-to-aromatics (MTA) process. Herein, Zn-containing HZSM-5 zeolites with hierarchical pores (H-Zn/HZSM-5) were prepared by treating directly synthesized Zn/HZSM-5 with NaOH solution. The changes in crystallinity, acidity and textural properties of Zn/HZSM-5 before and after alkali treatment were characterized by X-ray diffraction, NH3-TPD, 27Al MAS-NMR, N2 physisorption, X-ray fluorescence and TEM techniques. MTA reaction under the operating conditions of T = 400 °C and WHSV = 2.5 h−1 showed that the aromatic yield was improved from 41.4% for HZSM-5 to 55.3%. Furthermore, H-Zn/HZSM-5 exhibited a high initial space time yield of 0.62 g gcat−1 h−1 and a long lifetime up to 120 h. These results could be ascribed to the hierarchical pores and the providential acidity, which enhanced the adsorption and diffusion of intermediates/products during the reaction.
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      PubDate: 2016-06-14T14:22:29Z
       
  • The rational synthetic parameter analysis for subclasses of microporous
           aluminophosphates based on hierarchical feature selection model
    • Abstract: Publication date: 1 September 2016
      Source:Microporous and Mesoporous Materials, Volume 231
      Author(s): Yuting Guo, Zhenhua Tian, Na Gao, Miao Qi, Jianzhong Wang
      Open-framework aluminophosphates (AlPOs) is an important family of porous crystal materials. But the synthetic chemistry of this kind of materials is very complicated, and the synthesis mechanism has not been clearly understood yet. In this paper, we propose a Hierarchical Feature Selection Model (HFSM) composed of two layers to analyze the rational synthetic parameters for the subclass of microporous aluminophosphates (AlPOs) containing (6,8)-rings. In the first layer, we select a feature subset that could separate the (6,8)-ring-containing microporous AlPOs from other AlPOs. In the second layer, we further analyze which of these selected features are critical for the formation of each special subclass in (6,8)-ring-containing microporous AlPOs. With the optimal feature subset selected by the proposed model, we can obtain the highest accuracy rates as 94.28%, 94.03%, 91.27% and 92.20% for the classification of AEN, AWO, CHA and ERI, respectively. Extensive analysis is presented for the synthetic parameters selected by the hierarchical model, which could provide a useful guidance to the rational synthesis of such materials.
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      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.
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      PubDate: 2016-06-14T14:22:29Z
       
  • Structural rearrangements in Fe-porous clay heterostructures composites
           derived from Laponite® – Influence of preparation methods and
           Fe source
    • Abstract: Publication date: 1 September 2016
      Source:Microporous and Mesoporous Materials, Volume 231
      Author(s): M. Zimowska, J. Gurgul, H. Pálková, Z. Olejniczak, K. Łątka, L. Lityńska-Dobrzyńska, L. Matachowski
      In this study novel approach of Fe doped porous clay heterostructures synthesis by iron incorporation from the inorganic Fe(NO3)3·9H2O and metal-organic C6H5FeO sources, via post-synthesis route and pressure assistance, was described. Although post-synthesis impregnation proved to be sufficient method of porous clay heterostructures functionalization with iron species, the use of autoclaving ensured better dispersion of Fe nanostructures on the surface of clay derived supports. Appropriate choice of iron source was also essential to control formation of surface and sub-surface Fe species and incorporation of Fe into the selected lattice sites of the composite. The presence of ultrafine crystallites of α-Fe2O3 and Fe3O4 phases by TEM analysis supporting XRD measurement was evidenced. It turns out that high pressure treatment facilitated migration of trivalent heterocations along the composite network. It caused even complete iron embedding into the bulk/sub-surface lattice. The temperature transformation and pressure treatment not only influenced the composition and dispersion of the surface Fe species. It caused structure evolution of PCH composite, modification its textural properties, the increase of the average pore diameter (from 2.6 nm in PCH to 3.7 nm in FePCH-nit/aut and 4.5 nm in FePCH-cit/aut). Those phenomena influenced the catalytic activity of studied samples in ethanol decomposition. Transmission and reflection FTIR techniques in MIR and NIR regions, 57Fe Mössbauer and 29Si MAS-NMR spectroscopies were used to describe the structural rearrangements of PCH composites derived from Laponite® upon modified post-synthesis introduction of Fe and to distinguish between different species of Fe highly dispersed on the extended PCH surface.
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      PubDate: 2016-06-14T14:22:29Z
       
  • Investigation on porous properties of carbon/carbon composite cryogels by
           using weighted arithmetic mean
    • Abstract: Publication date: 1 September 2016
      Source:Microporous and Mesoporous Materials, Volume 231
      Author(s): Kriangsak Kraiwattanawong, Noriaki Sano, Hajime Tamon
      Cotton fibers (CF) and resorcinol and formaldehyde (RF) sol were used to synthesize composite cryogels. They were carbonized to prepare carbon/carbon (C/C) composite cryogels. In this work, the molar ratio of resorcinol to sodium carbonate (R/C), the mass concentration of resorcinol to distilled water (R/W) and the mass ratio of CF to RF (CF/RF) were changed as 100 and 200 mol/mol, 0.25 and 0.50 g/cm3 and 0.00 up to 0.64 g/g, respectively. The C/C composites were characterized by nitrogen adsorption and scanning electron microscopy. The results showed that the mesopore structure of C/C composites could be controlled by the adjustment of an R/W or R/C ratio. Moreover, the mean micropore sizes of C/C composite cryogels were kept equivalently to those of normal carbon cryogels. The weighted arithmetic mean was well applied to the BET surface area and micropore surface area of C/C composites with the deviation of about 21% for the high R/C ratio; however, it poor for the low R/C ratio. The weighted arithmetic mean also estimated the micropore volume of C/C composite cryogels with the deviation of about 20% for the CF/RF ratio smaller than 0.40 g/g. Moreover, the weighted arithmetic mean can be used as a guideline to estimate the mesopore volume.
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      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
       
  • Investigation of metal organic frameworks for the adsorptive removal of
           hydrochloride from dilute aqueous solution
    • Abstract: Publication date: 1 September 2016
      Source:Microporous and Mesoporous Materials, Volume 231
      Author(s): Xiaoyu Lan, Huanhuan Zhang, Peng Bai, Xianghai Guo
      In this paper, six kinds of reported water-stable MOFs, MIL-101(Cr), MIL-100(Cr, Fe), UiO-66, MIL-96(Al), and MIL-53(Cr) were evaluated as adsorbents for removal of hydrochloride from dilute aqueous solution. The as-synthesized products were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The results showed that UiO-66 exhibited excellent stability towards hydrochloride and the highest adsorption capacity among the six studied MOFs. Further researches on kinetics, thermodynamics, isotherms of adsorption process of hydrochloride on UiO-66 and its stability towards acid were investigated in detail. Moreover, a simple method was developed to free hydrochloride and recycle UiO-66 for repeated adsorption process, which showed UiO-66 may work as a good adsorbent for removal of hydrochloride from dilute aqueous solution.
      Graphical abstract image

      PubDate: 2016-06-14T14:22:29Z
       
  • Impact of mesoporous silica surface functionalization on human serum
           albumin interaction, cytotoxicity and antibacterial activity
    • Abstract: Publication date: 1 September 2016
      Source:Microporous and Mesoporous Materials, Volume 231
      Author(s): Małgorzata Ferenc, Nadia Katir, Katarzyna Milowska, Mosto Bousmina, Younes Brahmi, Aleksandra Felczak, Katarzyna Lisowska, Maria Bryszewska, Abdelkrim El Kadib
      Aiming to broaden our understanding on the interplay of silica nanomaterials with living biocells, we designed herein various surface-functionalized mesoporous SBA-15-type silicates, including native one SBA-OH, aminated SBA-NH 2 , thiolated SBA-SH and carboxy-terminated SBA-COOH. These high-surface area materials are then subjected to interactions with human serum albumin (HSA), in order to reproduce the real picture of what occurs within the body upon delivering active drugs. First, we examined circular dichroism measurements, fluorescence quenching, HSA adsorption and hemolysis in the presence and absence of HSA. Subsequently, we studied the toxicity of these materials toward eukaryotic and prokaryotic cells and the effect of the silica surface on the antibacterial activity. Irrespective to the functional groups, silica interacts with HSA resulting in the suppression of hemolysis. In terms of antibacterial activity, the pivotal parameter was found to be the amorphous state of the silica carrier rather than the nature of the functional groups. In the whole, this informative work provides an overall understanding of the role of the silica surface for bio-cells interaction and can serve as a guideline for the rational-design of blood-compatible nanomaterials.
      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
       
  • Influences of the confinement effect and acid strength of zeolite on the
           mechanisms of Methanol-to-Olefins conversion over H-ZSM-5: A theoretical
           study of alkenes-based cycle
    • Abstract: Publication date: 1 September 2016
      Source:Microporous and Mesoporous Materials, Volume 231
      Author(s): Wenna Zhang, Yueying Chu, Yingxu Wei, Xianfeng Yi, Shutao Xu, Jindou Huang, Mozhi Zhang, Anmin Zheng, Feng Deng, Zhongmin Liu
      Methanol-to-Olefins (MTO) conversion over acidic zeolite catalysts has become the most important non-petrochemical route for the production of light olefins. The ‘dual-cycle’ mechanism (i.e., alkenes-based cycle and aromatics-based cycle) over H-ZSM-5 zeolite has been generally accepted for olefins generation from methanol conversion. However, the relationship between the catalytic performance and the confinement effect/acid strength of the catalyst is still unclear. Herein, the methylation, isomerization and cracking processes involved in the alkenes-based cycle are discussed in-depth by density functional theory (DFT) calculations. The calculation results predicted that the transition states can be considerably stabilized by the van der Waals (vdW) interactions from the zeolite framework, resulting in the reduction of the activation barriers. And acid strength can also enhance the reaction activities. However, the catalytic reactivity of all elementary steps in the alkenes-based cycle can be improved at a different degree with increasing the acid strength. In addition, the ethene formation, transformation and the precursor of ethene formation need higher energy. And increasing acid strength can sharply decrease the activation barriers of ethene formation of cracking reaction, indicating that ethene formation may need strong acid strength.
      Graphical abstract image

      PubDate: 2016-06-14T14:22:29Z
       
  • Editorial Board
    • Abstract: Publication date: August 2016
      Source:Microporous and Mesoporous Materials, Volume 230




      PubDate: 2016-06-14T14:22:29Z
       
  • Magnetic mesoporous silica for water remediation: Synthesis,
           characterization and application as adsorbent of molecules and ions of
           environmental concern
    • Abstract: Publication date: August 2016
      Source:Microporous and Mesoporous Materials, Volume 230
      Author(s): Maximiliano Brigante, Eliana Pecini, Marcelo Avena
      Magnetic mesoporous silicas (NSMSiO2) were synthesized by coating nano-sized magnetite (NSM) particles with mesoporous silica shells. The effects of the NSM loading on the morphology, charge development and adsorption properties of the synthesized composites were investigated. Both the shape and the size of aggregates strongly changed as NSM/SiO2 molar ratio increased, i.e., from plates to spherical-like particles, in agreement with reduction on the silica shell thickness. The shell acted as a protective agent that minimized alteration of the magnetite structure and avoided magnetite dissolution in acidic media. The composites have a significant adsorption capacity towards a humic acid and the cationic dye malachite green, showing that they can adsorb both, anionic and cationic species. HA seems to enter the pores and bind the NSM cores, whereas malachite green binds mainly the silica shell. The effect of Ca2+ concentration on the adsorption capacity of the synthesized composite was also evaluated and discussed. The magnetic property of the materials facilitates the recuperation of the adsorbent from aqueous environments.
      Graphical abstract image

      PubDate: 2016-05-05T07:54:54Z
       
 
 
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