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Zeitschrift für angewandte Mathematik und Physik     Hybrid Journal   (Followers: 2)
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Microporous and Mesoporous Materials
Journal Prestige (SJR): 1.08
Citation Impact (citeScore): 4
Number of Followers: 9  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1387-1811
Published by Elsevier Homepage  [3163 journals]
  • Photoluminescence enhancement and morphological properties of nanoporous
           anodic alumina prepared in oxalic acid with varying time and temperature
    • Authors: K.S. Choudhari; Suresh D. Kulkarni; C. Santhosh; Sajan D. George
      Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): K.S. Choudhari, Suresh D. Kulkarni, C. Santhosh, Sajan D. George
      We report on the photoluminescence (PL) enhancement and morphological properties of highly ordered Nanoporous anodic alumina (NAA) fabricated by two-step anodization for 2–10 h at 5 °C and 25 °C anodization temperatures. Structural features and pore arrangements of NAA were characterized. Pore-properties such as pore-diameter, porosity and growth rate showed an increase with rising in temperature whereas pore-wall thickness and barrier layer thickness decreased, however, interpore distance and pore density were not affected. Two-dimensional fast Fourier Transform (FFT) analysis was used to study the pore arrangement. The average pore regularity ratio was higher at 5 °C. The Photoluminescence (PL) spectra of NAA samples exhibited a strong visible blue emission at room temperature. The broad PL peak was deconvoluted into two Gaussian sub-bands attributed to luminescent F+ and F centers. Experimental results showed that NAA prepared at elevated temperature showed PL enhancement by about 3.6–4.8 fold due to the increased anodizing current which leads to the increased density of F centers compared to F+ centers.
      Graphical abstract image

      PubDate: 2018-06-07T03:06:22Z
      DOI: 10.1016/j.micromeso.2018.06.004
      Issue No: Vol. 271 (2018)
       
  • Effect of Si-ATP/CTAB ratio on crystal morphology, pore structure and
           adsorption performance of hierarchical (H) ZSM-11 zeolite
    • Authors: Hong-Ji Li; Xiao-De Zhou; Yu Hui Di; Jian-Min Zhang; Yu Zhang
      Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): Hong-Ji Li, Xiao-De Zhou, Yu-Hui Di, Jian-Min Zhang, Yu Zhang
      In this manuscript, the micro-mesoporous crystals with the properties of (H) ZSM-11 zeolites were successfully obtained via one-pot synthesis in the hydrothermal system by using acidified attapulgite (Si-ATP) and cetyltrimethylammonium bromide (CTAB) as a precursor source (PS) and structure-directing agent (SDA), respectively. The effect of Si-ATP/CTAB ratio on controlling the crystal morphology and hierarchical pore structure of products was systematically investigated. The synthesized materials were characterized with XPS, XRD, FTIR, NMR, SEM, TEM and N2 adsorption-desorption analysis. Results demonstrate that the products possess not only a classical zeolite framework but also an adjustable mesoporous structure accompanied with a variety of Si-ATP/CTAB ratios. Meanwhile Si-ATP/CTAB ratio has a well linear dependence with hierarchy factor (HF) in lower or higher ranges. The MFI crystal transforms gradually to the MEL-structure under the action of CTAB when Si-ATP/CTAB ratio increases to 80: 5. In addition, (H) ZSM-11 zeolite, this ratio of 80: 5, mesoporosity and adsorption capacity of MB molecules was significantly enhanced. Advanced adsorption performance is attributed to the abundance hydroxyl group and the generated mesoporosity of the zeolite surface under the participation of CTAB. The experimental data are well fitted to the Langmuir isotherm model, with a correlation coefficient of 0.9962. The excellent adsorption performance makes such hierarchically porous (H) ZSM-11 zeolites attractive for applications in the field of energy and environment.

      PubDate: 2018-06-07T03:06:22Z
      DOI: 10.1016/j.micromeso.2018.05.039
      Issue No: Vol. 271 (2018)
       
  • Fabrication of Pt nanoparticles encapsulated in single crystal like
           silicalite-1 zeolite as a catalyst for shape-selective hydrogenation of C6
           olefins
    • Authors: Koji Miyake; Reina Inoue; Masahiro Nakai; Yuichiro Hirota; Yoshiaki Uchida; Shunsuke Tanaka; Manabu Miyamoto; Norikazu Nishiyama
      Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): Koji Miyake, Reina Inoue, Masahiro Nakai, Yuichiro Hirota, Yoshiaki Uchida, Shunsuke Tanaka, Manabu Miyamoto, Norikazu Nishiyama
      In this work, a dual-functional catalyst with (1) catalytic activity of metal catalysts and (2) shape-selectivity of zeolites has been developed. We have fabricated Pt nanoparticles encapsulated in core-shell single crystal like silicalite-1 zeolite (CS-Pt/s-1) by a crystalline overgrowth method. The CS-Pt/s-1 catalyst showed much higher catalytic hydrogenation activity of n-hexene compared to cyclohexene.
      Graphical abstract image

      PubDate: 2018-06-07T03:06:22Z
      DOI: 10.1016/j.micromeso.2018.05.051
      Issue No: Vol. 271 (2018)
       
  • The influence of the pore size in Metal−Organic Frameworks in adsorption
           and separation of hydrogen sulphide: A molecular simulation study
    • Authors: Thaer M. Al-Jadir; Flor R. Siperstein
      Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): Thaer M. Al-Jadir, Flor R. Siperstein
      Metal Organic Frameworks (MOFs) have the potential to be used as adsorbents in industrial separations. Different ligand lengths can generate MOFs with similar topology but differing pore sizes. Molecular simulations were used in this work to assess the adsorption isotherms, heats of adsorption and selectivity of H2S and CH4 in MOF UiO-66, UiO-67, and UiO-68. Detailed analysis of the distribution of molecules in the cages and the radial distribution functions suggest that the effect of the linker on the macroscopic properties is negligible at low pressures, but it becomes evident at high pressures, where adsorption far from the linker is observed in large pore materials. Based on the adsorption selection parameter, UiO-67 shows better performance in a wider range of conditions than the other materials.
      Graphical abstract image

      PubDate: 2018-06-07T03:06:22Z
      DOI: 10.1016/j.micromeso.2018.06.002
      Issue No: Vol. 271 (2018)
       
  • Selective pore opening and gating of the pillared layer metal-organic
           framework DUT-8(Ni) upon liquid phase multi-component adsorption
    • Authors: Negar Kavoosi; Tatiana Savchenko; Irena Senkovska; Mariia Maliuta; Volodymyr Bon; Alexander Eychmüller; Stefan Kaskel
      Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): Negar Kavoosi, Tatiana Savchenko, Irena Senkovska, Mariia Maliuta, Volodymyr Bon, Alexander Eychmüller, Stefan Kaskel
      The switchable metal-organic framework Ni2(ndc)2dabco (ndc - 2,6-naphthalenedicarboxylate, dabco - 1,4-diazabicyclo[2.2.2]octane), known as DUT-8(Ni) (DUT – Dresden University of Technology) is demonstrated to selectively respond with a crystal structure transformation and subsequent pore opening after exposure specifically to polar aprotic solvents, while a series of representative alcohols does not induce pore opening. A variety of more than 20 representative solvents was investigated with respect to liquid phase adsorption. The host-guest interaction is crucial for the transformation process directing the behaviour of the framework in response to the solvents with specific polarity and chemical constitution. The concentration dependence shown exemplarily for N,N-dimethylformamide/ethanol mixtures was monitored by UV–Vis, GC-MS and powder X-ray diffraction. In these binary mixtures, the adsorption proceeds along a prototypical “gate opening” isotherm, showing a pronounced step-like switching at a characteristic threshold concentration. Vapour adsorption isotherms confirm the highly selective recognition process and characteristic gating pressures observed depending on the guest-host interaction.
      Graphical abstract image

      PubDate: 2018-06-07T03:06:22Z
      DOI: 10.1016/j.micromeso.2018.05.024
      Issue No: Vol. 271 (2018)
       
  • Tin dioxide coated carbon materials as an alternative catalyst support for
           PEMFCs: Impacts of the intrinsic carbon properties and the synthesis
           parameters on the coating characteristics
    • Authors: Fabien Labbé; Elodie Disa; Yasser Ahmad; Katia Guérin; Tristan Asset; Frédéric Maillard; Marian Chatenet; Rudolf Metkemeijer; Sandrine Berthon-Fabry
      Pages: 1 - 15
      Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): Fabien Labbé, Elodie Disa, Yasser Ahmad, Katia Guérin, Tristan Asset, Frédéric Maillard, Marian Chatenet, Rudolf Metkemeijer, Sandrine Berthon-Fabry
      Several carbon materials (one carbon nanotubes, two carbon blacks and one home-made carbon aerogel) were covered by thin tin dioxide (SnO2) nanoparticles coatings to improve their resistance against oxidation under the working conditions of Proton Exchange Membrane Fuel Cells. A pretreatment for the nanotubes in acidic media was also performed to improve their dispersion in the reactive medium. The coating was done by a chemical route. Samples were analysed by Scanning Electronic Microscopy (SEM), nitrogen sorption, X-ray diffraction (XRD), Raman spectroscopy, Fourier Transformed InfraRed (FTIR) and X-ray Photoelectron Spectroscopy (XPS). Their electrical conductivities were also measured. Using a reactive medium with a pH value exceeding the point of zero charge of the carbon materials is mandatory to favour electrostatic attractions, and to obtain covering and homogeneous coatings. In this condition, it is possible to reduce the quantity of precursor and to optimise the coating. The intrinsic properties of the carbon materials also influence the characteristics of the coatings. In fact, the least organised carbon materials with high specific surface area and porosity values exhibit homogeneous and covering coatings. On the contrary, organised carbon materials, with few oxygen-containing groups, lead to a smaller quantity and heterogeneous coatings (with some areas of carbon surface uncovered). The pretreatment performed on the nanotubes improves the characteristics of the coatings, even if using significant amounts of precursor remains necessary to obtain a covering and a homogeneous coating. The transformation mechanisms of the precursor into tin dioxide, depending on the pH, value are also discussed.
      Graphical abstract image

      PubDate: 2018-05-29T02:49:56Z
      DOI: 10.1016/j.micromeso.2018.05.019
      Issue No: Vol. 271 (2018)
       
  • Soft-templated synthesis of mesoporous nickel oxide using
           poly(styrene-block-acrylic acid-block-ethylene glycol) block copolymers
    • Authors: Hamzeh Qutaish; Shunsuke Tanaka; Yusuf Valentino Kaneti; Jianjian Lin; Yoshio Bando; Abdulmohsen Ali Alshehri; Shin-Ichi Yusa; Yusuke Yamauchi; Md Shahriar A. Hossain; Jeonghun Kim
      Pages: 16 - 22
      Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): Hamzeh Qutaish, Shunsuke Tanaka, Yusuf Valentino Kaneti, Jianjian Lin, Yoshio Bando, Abdulmohsen Ali Alshehri, Shin-Ichi Yusa, Yusuke Yamauchi, Md Shahriar A. Hossain, Jeonghun Kim
      In this work, we report the soft-templated preparation of mesoporous nickel oxide using an asymmetric poly(styrene-block-acrylic acid-block-ethylene glycol) (PS-b-PAA-b-PEG) triblock copolymer. This block copolymer forms a micelle consisting of a PS core, a PAA shell and a PEG corona in aqueous solutions, which can serve as a soft template. Specifically, the PS block forms the core of the micelles on the basis of its lower solubility in water. The anionic PAA block interacts with the cationic Ni2+ ions present in the solution to generate the shell. The PEG block forms the corona of the micelles and stabilizes the micelles by preventing secondary aggregation through steric repulsion between the PEG chains. In terms of textural characteristics, the as-synthesized mesoporous NiO exhibits a large average pore size of 35 nm with large specific surface area and pore volume of 97.0 m2 g−1 and 0.411 cm3 g−1, respectively. It is expected that the proposed soft-templated strategy can be expanded to other metal oxides/sulfides in the future for potential applications in gas sensors, catalysis, energy storage and conversion, optoelectronics, and biomedical applications.
      Graphical abstract image

      PubDate: 2018-05-29T02:49:56Z
      DOI: 10.1016/j.micromeso.2018.05.015
      Issue No: Vol. 271 (2018)
       
  • A combined strategy of acid-assisted polymerization and solid state
           activation to synthesize functionalized nanoporous activated biocarbons
           from biomass for CO2 capture
    • Authors: Gurwinder Singh; Kripal S. Lakhi; Kavitha Ramadass; Sungho Kim; Declan Stockdale; Ajayan Vinu
      Pages: 23 - 32
      Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): Gurwinder Singh, Kripal S. Lakhi, Kavitha Ramadass, Sungho Kim, Declan Stockdale, Ajayan Vinu
      Novel acid treated porous activated biocarbons (APABs) are synthesized from biomass waste, Arundo donax, through sulphuric acid polymerization followed by a single step solid state activation using KOH at a fixed carbonization temperature of 600 °C. The specific surface area and the pore volume of the prepared materials is controlled by varying the ratio of KOH to biomass from 1 to 4. The sample prepared with the KOH/biomass ratio of 3 is found to be the best as it exhibits the specific surface area of 2232 m2 g−1 and a pore volume of 1.01 cm3 g−1 which is much higher than those of other samples prepared in this study. Interestingly, XPS and FT-IR studies confirm the presence of oxygen rich functional groups on the surface of the samples, which play an important role in enhancing the CO2 capture performance of the materials. Among the samples studied, the sample with the highest specific BET surface area exhibits the highest CO2 adsorption capacity of 21.2 mmol g-1 at 0 °C and 30 bar and a moderately high value of 4.1 mmol g-1 at 0 °C and 1 bar. The high CO2 adsorption capacity is attributed to the presence of excellent textural parameters coupled with high micropore volume and the oxygen functional groups. The samples are highly stable and do not show any change in the adsorption capacity even after repeated adsorption experiments. The combination of high adsorption capacity, stability and low cost makes these materials as a potential alternative to other expensive commercially available CO2 adsorbents.
      Graphical abstract image

      PubDate: 2018-05-29T02:49:56Z
      DOI: 10.1016/j.micromeso.2018.05.035
      Issue No: Vol. 271 (2018)
       
  • Comparative study of aluminosilicate glass and zeolite precursors in terms
           of Na environment and network structure
    • Authors: Hiroki Yamada; Sohei Sukenaga; Koji Ohara; Chokkalingam Anand; Mariko Ando; Hiroyuki Shibata; Tatsuya Okubo; Toru Wakihara
      Pages: 33 - 40
      Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): Hiroki Yamada, Sohei Sukenaga, Koji Ohara, Chokkalingam Anand, Mariko Ando, Hiroyuki Shibata, Tatsuya Okubo, Toru Wakihara
      Revealing structural features of the amorphous precursor of zeolite is an important research topic for elucidating formation mechanism of zeolites. To understand the zeolite precursor's comprehensive structural features, this study compared the precursor with the glass possessing similar compositions. By combining the high-energy X-ray total scattering method, 23Na-MQ-MAS-NMR, and reverse Monte Carlo simulation, we revealed structural differences among FAU-type zeolites, their precursors, and glass with similar compositions. As for crystallization behavior of FAU-type zeolite, pair distribution function and NMR analyses revealed that the environment of Na became gradually ordered during the crystallization. In addition, relaxation of large aluminosilicate rings was also confirmed. Comparison of the zeolite precursor and the glass clarified differences in Na–O distances and ring distributions, and simulation modeling supported these insights.
      Graphical abstract image

      PubDate: 2018-05-29T02:49:56Z
      DOI: 10.1016/j.micromeso.2018.05.006
      Issue No: Vol. 271 (2018)
       
  • The pore length, the pore number and the pore anisotropy distributions in
           porous materials
    • Authors: Philippos Pomonis; Antigoni Margellou
      Pages: 41 - 51
      Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): Philippos Pomonis, Antigoni Margellou
      The differential pore lengths L i , the differential pore numbers N i and the differential pore anisotropies B i in porous materials are estimated in a unified way and presented as a function of pore radius r i . Those parameters can be determined from the differential specific surface area S i and the differential specific pore volume V i calculated via nitrogen porosimetry, assuming cylindrical pores. The differential pore length is estimated from relation L i  = S i 2 /V i  = N i ·l i and corresponds to the total length of N i pores with similar local length l i at each pore group of radius r i estimated at partial pressure (P i /P o ). This parameter bears similarities with the differential pore anisotropy B i given by B i  = S i 3 /V i 2  = N i ·b i where b i is the local pore anisotropy. Parameter B i is suitable for the ranking of pore numbers vs. pore volumes and, for isotropic cavities with bi = 1, leads to the ranking of pores according to the Zipf's law. Parameter L i is suitable for the ranking of pore lengths as a function of pore radii and reveals some morphometric similarities between the pore networks in solids and the branching of trees described by the so-called allometric relations. In addition these relations may be used for the distinction of pore number evolution via either power law or exponential mechanisms, expressed by corresponding distributions. Such effects, observed previously by volcanologists in the vesicles of volvanic magmas in mm scale, are also observed in the present study for random pores of nm scale in lab made materials.
      Graphical abstract image

      PubDate: 2018-05-29T02:49:56Z
      DOI: 10.1016/j.micromeso.2018.05.041
      Issue No: Vol. 271 (2018)
       
  • Facile synthesis of a mesoporous organic polymer grafted with
           2-aminoethanethiol for Hg2+ removal
    • Authors: Seenu Ravi; Wha-Seung Ahn
      Pages: 59 - 67
      Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): Seenu Ravi, Wha-Seung Ahn
      By varying the amount of AlCl3 catalyst, highly interconnected lamella-shaped (IPOP) and spherically structured porous organic polymers (SPOP) were synthesized from terephthaloyl chloride and p-quaterphenyl via the Friedel–Crafts benzoylation reaction. The newly prepared materials were characterized by scanning electron microscopy, N2 adsorption-desorption isotherms, X-ray photoelectron spectroscopy, and tested for Hg2+ removal in water after functionalization with 2-aminoethanethiol (NS). The stability under different pH and temperature conditions was confirmed, and the equilibrium and kinetics of Hg2+ adsorption were examined by varying the contact time, adsorbate concentration, and pH. The maximum adsorption capacities for Hg2+ by IPOP-NS and SPOP-NS were 769 and 526 mg g−1, respectively, at 25 °C and pH 5, and the adsorption isotherm data conformed well to the Langmuir model. Adsorption equilibrium for IPOP-NS was reached within 10 min and exhibited a remarkable distribution coefficient of 1.06 × 108 mL g−1. The kinetics of Hg2+ adsorption followed the pseudo-second-order model. The influence of co-existing ions such as Na+, K+, Ca2+, Pb2+, Mg2+, and Fe3+ was also examined. IPOP-NS was superior in overall performance when compared to SPOP-NS and most of the other reported materials. IPOP-NS could be reused for a minimum of 10 consecutive runs without any detectable loss in adsorption capacity.
      Graphical abstract image

      PubDate: 2018-06-01T02:54:46Z
      DOI: 10.1016/j.micromeso.2018.05.038
      Issue No: Vol. 271 (2018)
       
  • In-situ fabrication of ZIF-8 decorated layered double oxides for
           adsorption and photocatalytic degradation of methylene blue
    • Authors: Mengqing Hu; He Lou; Xinlong Yan; Xiaoyan Hu; Rui Feng; Min Zhou
      Pages: 68 - 72
      Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): Mengqing Hu, He Lou, Xinlong Yan, Xiaoyan Hu, Rui Feng, Min Zhou
      Combining metal-organic frameworks (MOFs) with a variety of functional materials have received considerable attention recently due to their enhanced performances and widespread applications. In this work, ZIF-8/Zn-Al Layered double oxides (LDO) composite was synthesized via in-situ growth method without adding any zinc source. Hierarchical porous structure was formed by the growth of ZIF-8 onto LDO surface, and the resulted composite exhibited high adsorption capacity and good photocatalytic degradation activity for methylene blue (MB). More than 58% of the initial concentration of MB could be adsorbed and degraded within 180 min of UV irradiation, which was significant higher than that of ZIF-8 and LDO, suggesting a synergy of adsorption and photocatalysis between ZIF-8 and LDO. Moreover, ZIF-8/LDO could be easily regenerated and reused at least 4 times without loss of its degradation ability.
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      PubDate: 2018-06-01T02:54:46Z
      DOI: 10.1016/j.micromeso.2018.05.048
      Issue No: Vol. 271 (2018)
       
  • Binary adsorption equilibrium and breakthrough of toluene and cyclohexane
           on macroporous and hypercrosslinked polymeric resins
    • Authors: Qiuyi Shi; Xinyu Yang; Liuyan Wu; Huijuan Liu; Jian Zhang; Feng Zhang; Chao Long
      Pages: 73 - 82
      Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): Qiuyi Shi, Xinyu Yang, Liuyan Wu, Huijuan Liu, Jian Zhang, Feng Zhang, Chao Long
      Adsorption-based separation is one of the most widely used methods in treating gasoline vapor. For effective control of gasoline vapor emission, the total concentration of non-methane hydrocarbons (NMHC) and the specific component such as toluene must meet the emission limit values. In this study, hypercrosslinked polymeric resin (Hyper-resin) and macroporous polymeric resin (Macro-resin) were selected as adsorbents. Toluene and cyclohexane were chosen as the representative of alkanes and aromatic hydrocarbons components of gasoline vapor. Pure and binary component adsorption isotherms of toluene and cyclohexane on two resins were measured by head space analysis method. Breakthrough data for binary system were obtained at the different concentrations of toluene (12–46 mg/L) and cyclohexane (15 mg/L and 102 mg/L) using a fixed-bed reactor. The results indicate that adsorption equilibria of binary component can be predicted by ideal adsorbed solution theory (IAST) with the average relative error lower than 15% using the pure component adsorption isotherm data. Hyper-resin provides higher selectivity to toluene than Macro-resin in binary equilibrium and breakthrough system. Moreover, the breakthrough adsorption capacities of pure component (toluene and cyclohexane) and their mixture on Hyper-resin are higher than those on Macro-resin, suggesting Hyper-resin would be a promising adsorbent for treating gasoline vapor.
      Graphical abstract image

      PubDate: 2018-06-01T02:54:46Z
      DOI: 10.1016/j.micromeso.2018.05.034
      Issue No: Vol. 271 (2018)
       
  • Mg3Si4O10(OH)2 and MgFe2O4 in situ grown on diatomite: Highly efficient
           adsorbents for the removal of Cr(VI)
    • Authors: Yucheng Du; Xuekai Wang; Junshu Wu; Jinshu Wang; Yang Li; Hongxing Dai
      Pages: 83 - 91
      Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): Yucheng Du, Xuekai Wang, Junshu Wu, Jinshu Wang, Yang Li, Hongxing Dai
      Diatomite is a kind of nonmetallic mineral that possesses ordered micro- and mesoporous structures, and is well substrate materials for loading highly active oxide nanostructures for the removal of heavy metal ions. In this work, the Mg3Si4O10(OH)2 and MgFe2O4 nanosheets were loaded on diatomite via a facile hydrothermal method. The Mg3Si4O10(OH)2/diatomite sample had a specific surface area of 149 m2/g and an extremely large adsorption capacity of 535 mg/g for Cr(VI) adsorption at room temperature, and the MgFe2O4/diatomite sample possessed a higher surface area of 335 m2/g and a larger capacity of 570 mg/g for Cr(VI) adsorption under UV light irradiation. The Cr(VI) adsorbed on the surface of MgFe2O4/diatomite was reduced to the less toxic Cr(III). The synergistic effect of between adsorption and photocatalysis might be the main reasons why the MgFe2O4/diatomite sample was superior to the Mg3Si4O10(OH)2/diatomite sample in Cr(VI) removal capacity and efficiency. It is assured that such adsorbents have a great potential for practical applications in the removal of heavy metal ions in wastewater.
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      PubDate: 2018-06-04T02:59:54Z
      DOI: 10.1016/j.micromeso.2018.04.036
      Issue No: Vol. 271 (2018)
       
  • Easily tunable hydrogel-derived heteroatom-doped hierarchically porous
           carbons as multifunctional materials for supercapacitors, CO2 capture and
           dye removal
    • Authors: Liang Liang; Minghua Zhou; Chaolin Tan; Xiaoyu Tian; Kerui Li
      Pages: 92 - 99
      Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): Liang Liang, Minghua Zhou, Chaolin Tan, Xiaoyu Tian, Kerui Li
      It is attractive to develop multifunctional materials for practical applications. Herein, heteroatom-doped hierarchically porous carbons (HPCs) are prepared through a simple pyrolysis of monolithic hydrogels derived from glucose, followed by chemical activation using KOH as an activator at 600–1000 °C. With different activation temperature, the pore structure and surface chemistry of the resulting HPCs can be easily tuned and the corresponding performances in supercapacitors, CO2 capture and dye adsorption are further investigated. HPC800 with the largest micropore volume (0.58 cm3 g−1) exhibits a high specific capacitance of 249 F g−1 at 1 A g−1 and an excellent cycling stability with 94% of the capacitance retention after 1000 cycles as supercapacitors electrodes. Meanwhile, HPC800 shows the remarkable adsorption capacity of CO2 (4.4 mmol g−1 at 25 °C, 1 atm). For methylene blue (MB) adsorption, the maximum adsorption capacity of 720 mg g−1 is obtained on HPC1000 with the highest specific surface area (2302 m2 g−1) and total pore volume (1.10 cm3 g−1). The CO2 and MB adsorption capacities are both higher than most of the reported adsorbents. It is demonstrated that CO2 and MB adsorption capacity are determined by the volume of pore with diameter <0.8 and 2.8 nm, respectively (both about 2.4 times larger than the size of adsorbates). The prepared HPCs are promising candidates for practical applications in both energy-related and environmental fields.
      Graphical abstract image

      PubDate: 2018-06-07T03:06:22Z
      DOI: 10.1016/j.micromeso.2018.05.050
      Issue No: Vol. 271 (2018)
       
  • Zeolite encapsulated host-guest Cu(II) Schiff base complexes: Superior
           activity towards oxidation reactions over homogenous catalytic systems
    • Authors: Bidyut Kumar Kundu; Vaishali Chhabra; Novina Malviya; Rakesh Ganguly; Gopal S. Mishra; Suman Mukhopadhyay
      Pages: 100 - 117
      Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): Bidyut Kumar Kundu, Vaishali Chhabra, Novina Malviya, Rakesh Ganguly, Gopal S. Mishra, Suman Mukhopadhyay
      Crystalline copper Schiff base complexes of general formula [CuL1NO3]n (1) and [CuL2Cl] (2) (where HL1 = 1-[(3-dimethylaminopropylimino)-methyl]-naphthalen-2-ol and HL2 = 3-[(3-dimethylamino-2,2-dimethyl-propylimino)-methyl]-naphthalen-2-ol) were prepared and well characterized. The guest, metal complexes were entrapped in the supercages of NaY zeolite (host) in the solvent phase through two stage process (i) ion exchange of the selected transition metal (Cu(II)-salt) in the porous structure and (ii) encapsulation of Schiff-base ligands (HL1/HL2) in Cu(II) exchanged zeolite. The novel Cu(II) complexes as well as host-guest catalysts were characterized using various physicochemical [Single crystal XRD, elemental analysis, EDX, scanning electron microscopy (FE-SEM), the Brunauer-Emmet-Teller (BET) adsorption technique (N2 gas), Inductively coupled plasma (ICP-MS), powder X-ray diffraction (PXRD), thermal analysis (TGA), cyclic voltametry] and spectroscopic techniques [1H and 13C NMR, FT-IR, ESI-MS, electro spin resonance (ESR), diffuse reflectance spectroscopy (DRS), FT-Raman and GC-MS]. Herein, this study reveals the advantage of heterogeneous catalytic methods for the stability of metal complexes into the supercages of zeolite-Y and the selective oxidation of phenol, styrene and cyclohexene in presence of H2O2 at mild reaction conditions. The catalytic activities of the zeolite entrapped Cu(II) complexes were tested with their homogeneous analogous as well. The heterogeneous catalyst can be re-used after recovering for several cycles without decay of activity which was confirmed by PXRD, cyclic voltammetry, SEM and FTIR studies.
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      PubDate: 2018-06-07T03:06:22Z
      DOI: 10.1016/j.micromeso.2018.05.046
      Issue No: Vol. 271 (2018)
       
  • Insight into controllability and predictability of pore structures in
           pitch-based activated carbons
    • Authors: Taotao Guan; Jianghong Zhao; Guoli Zhang; Dongdong Zhang; Baixin Han; Nan Tang; Jianlong Wang; Kaixi Li
      Pages: 118 - 127
      Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): Taotao Guan, Jianghong Zhao, Guoli Zhang, Dongdong Zhang, Baixin Han, Nan Tang, Jianlong Wang, Kaixi Li
      Tailoring porosity of pitch-based activated carbons (PACs) on a large scale is of high importance and usually achieved by introducing additives or templates and adjusting activation conditions. Since pitch is a kind of extraordinarily complex mixtures, it is highly necessary to investigate the effect of pitch composition on pore structure of PACs. Herein, a coal-tar pitch was subdivided by solvent fractionation into toluene-soluble (TS), pyridine-soluble (PS), quinoline-soluble (QS), and quinoline-insoluble (QI) fractions followed by activation using KOH or steam, respectively, to obtain PACs. It is found that the formation of pores in PACs is significantly dependent on pitch composition and activation methods. The light fractions (TS and PS) are more favorable for pore development in the KOH-activated carbons, whereas pores in the H2O-activated carbons are easily achieved by using the heavy fractions (QS and QI). The possible pore-formation mechanisms were also proposed, which indicates that the big differences intrinsically originate from the chemical properties (such as molecular size, structures, reactivity with activation agents and rheological behaviors of the molecular aggregations) of pitch compositions. When commercial pitches are employed for the precursors, a synergistic effect on pore development occurs both in KOH- and H2O-activated PACs seriously depending on their mass percentages of light or heavy fractions. It suggests that the mass percentage can be an index to foresee the porous properties of PACs. These findings open up a significantly important and more practical approach applicable to tailor the pores in PACs on an industrial scale just through adjusting pitch compositions.
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      PubDate: 2018-06-07T03:06:22Z
      DOI: 10.1016/j.micromeso.2018.05.036
      Issue No: Vol. 271 (2018)
       
  • Biosynthesis, characterization and catalytic activity of the Pd/bentonite
           nanocomposite for base- and ligand-free oxidative hydroxylation of
           phenylboronic acid and reduction of chromium (VI) and nitro compounds
    • Authors: Mahmoud Nasrollahzadeh; S. Mohammad Sajadi; Mehdi Maham; Iraj Kohsari
      Pages: 128 - 137
      Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): Mahmoud Nasrollahzadeh, S. Mohammad Sajadi, Mehdi Maham, Iraj Kohsari
      In this study, an eco-friendly method was developed to synthesize Pd/bentonite nanocomposite using Gardenia taitensis leaf extract and bentonite as a natural support. The suggested method has the benefits of simple work up, high yields and elimination of toxic chemicals. The biosynthesized nanocomposite was characterized by FT-IR, TEM, FESEM, EDS, and XRD. The stability studies showed that the biosynthesized Pd nanoparticles (NPs) have a good durability even for more than 2 weeks. The catalytic activity of the prepared nanocatalyst was evaluated in the ligand-free hydroxylation of phenylboronic acid to phenol and reduction of the chromium (VI) (Cr(VI)) and nitro compounds such as 4-nitrophenol (4-NP) and 2,4-dinitrophenylhydrazine (2,4-DNPH). The as-prepared catalyst was reused at least 5 times without remarkable loss in its catalytic activity.
      Graphical abstract image

      PubDate: 2018-06-07T03:06:22Z
      DOI: 10.1016/j.micromeso.2018.05.045
      Issue No: Vol. 271 (2018)
       
  • Hydrogen separation by adsorption: Experiments and modelling of H2-N2-CO2
           and H2-CH4-CO2 mixtures adsorption on CuBTC and MOF-5
    • Authors: F.A. Kloutse; A. Hourri; S. Natarajan; P. Benard; R. Chahine
      Pages: 175 - 185
      Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): F.A. Kloutse, A. Hourri, S. Natarajan, P. Benard, R. Chahine
      In this paper, we present the adsorption data of two ternary mixtures (H2-N2-CO2 and H2-CH4-CO2) on MOF-5 and CuBTC, obtained via a recirculating volumetric method. The measurements were performed along constant composition and constant pressure domains. The constant pressure data outlines the existence of one-component azeotrope-like crossovers in the adsorbed phase diagrams. Such azeotropic behaviours are related to the deviation between selectivities in the ternary and the equivalent binary mixtures. Furthermore, the capabilities of three models, Extended Langmuir, Extended Toth and Ideal Adsorption Solution Theory (IAST), to predict the ternary mixture adsorption from pure-component data are discussed.
      Graphical abstract image

      PubDate: 2018-06-10T03:13:53Z
      DOI: 10.1016/j.micromeso.2018.05.042
      Issue No: Vol. 271 (2018)
       
  • One-pot catalytic hydrolysis/hydrogenation of cellobiose into hexitols
           over Ru/Al-MCM-48
    • Authors: A. Romero; J.A. Díaz; A. Nieto-Márquez; N. Essayem; E. Alonso; C. Pinel
      Pages: 186 - 195
      Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): A. Romero, J.A. Díaz, A. Nieto-Márquez, N. Essayem, E. Alonso, C. Pinel
      The simultaneous catalytic hydrolysis and hydrogenation of cellobiose, as a model constituent of biomass has been studied over Ru/Al-MCM-48. The catalyst, presenting both acidic and hydrogenating functions has been synthesized and characterized by means of N2 adsorption-desorption, SAXS, H2-TPR, XRD, TEM and NH3-TPD. A kinetic model is proposed, and possible reaction pathways and key intermediate compounds of conversion of cellobiose to hexitols are discussed. In the kinetic study the effects of pressure, temperature and time on the one-pot reaction were evaluated. A maximum yield around 91% of hexitols was achieved at 180 °C, 5 MPa of H2 and 7 min, where sorbitol was the main compound in the final product with 82% yield. Cellobitol was the main reaction intermediate. Temperatures in the range of 140–180 °C and pressures in the range of 3–5 MPa of H2 were studied and it was concluded that higher temperatures and pressures had a positive effect in order to maximize the production of hexitols. The developed kinetic model predicted with high accuracy the concentration of the different compounds involved in the proposed reaction pathway and served to calculate the reaction rate constant and activation energy values for the different steps of the catalytic process.
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      PubDate: 2018-06-10T03:13:53Z
      DOI: 10.1016/j.micromeso.2018.06.003
      Issue No: Vol. 271 (2018)
       
  • Sol-gel synthesis of SBA-15: Impact of HCl on surface chemistry
    • Authors: Cyril Pirez; Jean-Charles Morin; Jinesh C. Manayil; Adam F. Lee; Karen Wilson
      Pages: 196 - 202
      Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): Cyril Pirez, Jean-Charles Morin, Jinesh C. Manayil, Adam F. Lee, Karen Wilson
      Surface functionalisation of mesoporous silicas is critical to their application as sorbents and catalyst supports. Here we report the impact of chloride on the physicochemical properties of SBA-15, notably the surface density of reactive hydroxyl groups. Bulk and surface properties were characterised by N2 porosimetry, X-ray diffraction, SEM, TEM, FTIR spectroscopy, and Inverse gas chromatography (IGC). Increasing the HCl concentration from 0.1 → 2.0 M during the sol-gel preparation of SBA-15 increased the surface silanol coverage two-fold, and slightly widened mesopores from 4.2 to 4.9 nm. IGC reveals that the specific surface energy and corresponding surface polarity of SBA-15 correlate with surface silanol properties, and hence tuning the HCl concentration during SBA-15 synthesis offers a facile route to hydrophilic or hydrophobic silicas, and in turn a means to control their functionalisation and sorptive properties.
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      PubDate: 2018-06-10T03:13:53Z
      DOI: 10.1016/j.micromeso.2018.05.043
      Issue No: Vol. 271 (2018)
       
  • On the interrelationship of porosity and structural defects in
           amorphous-crystalline nanopowders SiO2-doped Gd2O3 with their magnetic and
           luminescent properties
    • Authors: V.G. Ilves; A.M. Murzakaev; S. Yu Sokovnin
      Pages: 203 - 218
      Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): V.G. Ilves, A.M. Murzakaev, S. Yu Sokovnin
      The pulsed electron beam evaporation method (PEBE) was used to obtain mesoporous amorphous-crystalline pure and SiO2-doped Gd2O3 nanopowders (NPs). An HRTEM phase analysis showed the existence in nanopowder Gd2O3 of an amorphous, as well as three crystalline phases. The influence of silicon oxide doping on the textural, magnetic and luminescent properties of NPs Gd2O3@SiO2 was studied. The size and volume of the interparticle pores of NPs Gd2O3@SiO2 was dependant on the concentration of a dopant. The doping supported an increase in amorphicity and the growth of a concentration of different structural defects in NPs. Two different processes – annealing and doping, led to crystallinity degradation of the Gd2O3 matrix. The correlation of porosity concentration dependences, paramagnetic response, and the intensity of pulsed cathodoluminescence spectra in NPs Gd2O3@SiO2 was revealed. The dependence of the paramagnetic response Gd2O3 on the volume of interparticle mesopores in nonporous nanoparticles expands our understanding of the nature of diluted magnetic semiconductors.
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      PubDate: 2018-06-10T03:13:53Z
      DOI: 10.1016/j.micromeso.2018.05.044
      Issue No: Vol. 271 (2018)
       
  • Synthesis of titanium-aluminum binary oxides stabilized by
           polyvinylpyrrolidone and their application for catalytic nitration of
           arenes
    • Authors: Heng Yu; Chao Fan; Yu Cheng; Benhua Huang; Yu Li; Junjie Zhang; Aqun Zheng; Yang Sun
      Pages: 219 - 233
      Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): Heng Yu, Chao Fan, Yu Cheng, Benhua Huang, Yu Li, Junjie Zhang, Aqun Zheng, Yang Sun
      A series of titanium-aluminum binary oxides are prepared through co-precipitation of metal salts with polyvinylpyrrolidone (PVP) in alkaline solution, along with dehydration. Most of synthetic oxides are composed of micro- or nano-sized blocks, while one of them shows an interesting two-dimensional morphology. Furthermore, loading of aluminum into co-precipitation would increase product porosity compared with the non-loaded case, while addition of PVP shows influences on building micropores of synthetic oxide. In catalysis, the synthetic oxides usually show high activities for nitration of various arenes. The key factors affecting catalytic outputs are carefully discussed, and the matching relation between shape of substrate and pore distribution of catalyst may affect catalytic efficiency too. Moreover, the binary oxide featuring PVP shows more durable recycling behavior than the non-doped one. On the other hand, nitration reactions of naphthalene and benzene halides show better stereoselectivities than those of alkylbenzenes. In general, this study may contribute to the catalytic progress of new oxide materials.
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      PubDate: 2018-06-10T03:13:53Z
      DOI: 10.1016/j.micromeso.2018.06.006
      Issue No: Vol. 271 (2018)
       
  • Key factors for the direct growth of zeolite faujasite (FAU) on metallic
           aluminum surface
    • Authors: Rajesh Chanda; Thangaraj Selvam; Yamini S. Avadhut; Andreas Kuhnt; Ralph Herrmann; Martin Hartmann; Wilhelm Schwieger
      Pages: 252 - 261
      Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): Rajesh Chanda, Thangaraj Selvam, Yamini S. Avadhut, Andreas Kuhnt, Ralph Herrmann, Martin Hartmann, Wilhelm Schwieger
      Zeolite faujasite (FAU) is widely used as a catalyst and adsorbent in many industrial catalytic and separation applications. The high water adsorption capacity of zeolite FAU makes it an attractive adsorbent material for the heat pump and heat storage applications. However, highly alkaline condition, which is required for the synthesis of zeolite FAU, is a challenge to achieve FAU/aluminum composites via a direct, reactive coating approach. In this contribution, a reactive coating method to fabricate zeolite FAU based aluminum composites is presented. The impact of important synthesis paramaters on the formation of such composites is discussed based on thorough characterization (such as XRD, SEM, MAS NMR, N2- and water-sorption) of the coated FAU layer (the composite) and so-called excess powder, formed parallel in the reaction solution. Along with the comprehensive study of zeolite FAU formation as a coating layer, preliminary results of the fabricated composites in potential heat pump application are presented as well.
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      PubDate: 2018-06-10T03:13:53Z
      DOI: 10.1016/j.micromeso.2018.05.037
      Issue No: Vol. 271 (2018)
       
  • Comparative analysis of nanopore structure and its effect on methane
           adsorption capacity of Southern Junggar coalfield coals by gas adsorption
           and FIB-SEM tomography
    • Abstract: Publication date: December 2018
      Source:Microporous and Mesoporous Materials, Volume 272
      Author(s): Sandong Zhou, Dameng Liu, Yidong Cai, Zuleima Karpyn, Yanbin Yao
      Nano-scale porous structure has a significant influence on methane adsorption in coal seam. This work presents a comparative analysis of different experimental techniques for evaluating pore structure and the relationship between pore surface area and roughness with methane adsorption capacity. This sorption capacity subsequently affects the accuracy of total gas-in-place estimates and feasibility of CO2 injection for enhanced natural gas recovery. To evaluate methane adsorption characteristics of nanopores (<100 nm), various laboratory analyses are presented. Surface area, porosity, pore volume and fractal analysis of adsorption pores were determined in 13 coal samples (maximum vitrinite (huminite) reflectance <1.0%) using gas (CO2, N2 and CH4) adsorption and focused ion beam scanning electron microscopy (FIB-SEM) tomography. FIB-SEM images indicate a clustered distribution of multi-scale adsorption pores with similar orientation. The macropores connect some mesopores, which enhance gas flow and have a positive influence on coal permeability. The percent of connected pores compared to the number of total nanopores is ∼2% in selected samples, as calculated by FIB-SEM. Surface area and pore volume distribution determined from FIB-SEM are consistently higher than those obtained from N2 adsorption methods. In general, the FIB-SEM technique can detect both isolated and connected mesopores and macropores but cannot measure micropores. Surface area, pore volume, and porosity that estimates from N2 adsorption tests are prone to underestimate actual conditions. Langmuir volume (9.92–24.42 m3/t) are seemingly independent of maceral composition and coal ranks in this set of samples, having no direct correlations. Methane adsorption capacity increases with increasing the adsorption pore surface area and fractal dimensions and follow a moderate straight-line relationship. Hence, methane adsorption capacity is directly influenced by micropore surface area and micropore roughness. These results are significant for understanding the interaction of coal with gases.
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      PubDate: 2018-06-22T15:03:53Z
       
  • Mechanochemical synthesis of supported cobalt oxide nanoparticles on
           mesoporous materials as versatile bifunctional catalysts
    • Abstract: Publication date: December 2018
      Source:Microporous and Mesoporous Materials, Volume 272
      Author(s): Antonio Pineda, Manuel Ojeda, Antonio A. Romero, Alina M. Balu, Rafael Luque
      Supported Co3O4 nanoparticles on SBA-15 aluminosilicates (Al-SBA-15) with different cobalt loadings (0.5, 1, 5, 10 wt %) were synthesized by ball-milling. The synthesized materials were characterized by different techniques including, N2 adsorption measurements, XRD, TEM, EDX, ICP-MS, DRIFTs of pyridine among others. The catalysts were studied in the microwave assisted benzyl alcohol oxidation as well as in the akylation of toluene with benzyl chloride. Co3O4 catalysts exhibited moderate conversions in the selective oxidation of benzyl alcohol, with a high selectivity towards benzaldehyde. Lewis acidity increases upon the incorporation of cobalt nanoparticles onto the surface of the support which was found to significantly influence the materials in the alkylation of toluene with benzyl chloride. The high active sites accessibility of ball-milling prepared materials leads to high conversions to alkylated derivatives in short periods of time (>99 mol %, 30 min). A direct correlation acidity/activity could not be obtained in the systems, for which nanoparticle sizes and distribution could influence the observed activities.
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      PubDate: 2018-06-22T15:03:53Z
       
  • Thermal stability and dehydration of armstrongite, a microporous zirconium
           silicate
    • Abstract: Publication date: December 2018
      Source:Microporous and Mesoporous Materials, Volume 272
      Author(s): E. Schingaro, M. Lacalamita, E. Mesto, G. Della Ventura
      The dehydration of armstrongite from Khan Bogdo (Mongolia) was investigated by combining thermal analysis, in situ HT X-ray powder diffraction (XRPD) and Fourier Transform InfraRed (FTIR) spectroscopy. The process starts at ∼380 °C and is completed within few tenths of degrees. It involves a mass loss of 6.1 wt% and a cell volume decrease of 7%. Armstrongite at RT has C2/m symmetry with (in Å) a = 14.010 (2), b = 14.115 (1), c = 7.838 (1), β = 109.387 (3)°, V = 1462.2 (2) Å3. XRPD data in the T-range 370–400 °C show a significant contraction of the cell volume without any symmetry change. At 400 °C the dehydrated phase has cell dimensions (in Å): a = 13.425 (2), b = 13.752 (1), c = 7.818 (1), β = 110.246 (3)°, V = 1354.2 (2) Å3. The patterns collected in the T-range from 800 to 30 °C show that armstrongite rehydrates quickly at T ∼320 °C; unit cell parameters and volume refined at the end of the heating/cooling cycle point to a complete reversibility of the dehydration process. Fast rehydration upon cooling is also evident in the FTIR spectra; a complete recovery of the OH-stretching and bending signals is observed at T ∼280–300 °C. Notably, this process can be monitored on single-crystals, while powders embedded in KBr pellets do not recover the structural water content. The thermal expansion of armstrongite is more pronounced along the b axis, with α a : α b : α c  = 1.09 × 10−6: 1.69 × 10−5: 7.61 × 10−7 at 90 °C and 7.73 × 10−6: 8.94 × 10−6: 5.85 × 10−6 at 800 °C.
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      PubDate: 2018-06-22T15:03:53Z
       
  • Influence of the interaction between surfactants and sepiolite on the
           rheological properties and thermal stability of organo-sepiolite in
           oil-based drilling fluids
    • Abstract: Publication date: December 2018
      Source:Microporous and Mesoporous Materials, Volume 272
      Author(s): Guanzheng Zhuang, Zepeng Zhang, Huiwen Chen
      The influence of interaction between organic surfactants and sepiolite (Sep) on the structure and rheological properties of organo-sepiolite (OSep) in oil-based drilling fluids was investigated. Sep was modified with three kinds of cationic surfactant. X-ray diffraction, scanning electron microscope, surface properties, thermal analysis and X-ray photoelectron spectroscopy (XPS) were applied to characterize the structures of OSep and interaction between surfactants and Sep. Gel volume and dynamic rheological behavior were used to appraise the rheological properties of OSep/oil fluids. OSep keeps the crystal structure of sepiolite after organic modification and shows the more dispersed fibers. XPS results demonstrated that organic surfactants are in electronic interaction with sepiolite. Surfactants block the micropores of sepiolite by partially inserting and covering, resulting in the decrease of specific surface area. The size of the surfactants plays an important role to insert the channels. The partially insertion of surfactants into the channels leads to better rheological properties and thermal stability of OSep in oil-based drilling fluids.
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      PubDate: 2018-06-22T15:03:53Z
       
  • Facile synthesis of soft-templated carbon monoliths with hierarchical
           porosity for fast adsorption from liquid media
    • Abstract: Publication date: December 2018
      Source:Microporous and Mesoporous Materials, Volume 272
      Author(s): Petra Bulavová, Julien Parmentier, Václav Slovák
      An easy synthesis of carbon monoliths with hierarchical porosities is presented here combining phenolic sol-gel and soft-templating methods (use of amphiphilic surfactant Pluronic F127 as mesopores template). By varying the synthesis conditions, purely microporous or micro-mesoporous or micro-meso-macroporous carbon materials were obtained. While micropores and mesopores arise during the carbonisation, macropores formation occurs during the gelling step through a controlled macroscopic phase separation process. The same pyrolytic temperature was used to ensure comparable surface chemistry (proved by FTIR and TGA-MS measurements for the templated samples), textural properties were investigated by a group of techniques: TEM, CO2 and N2 sorption, Hg porosimetry and SAXS. The benefit of the different porosities was evidenced on blocs of 1–2.5 mm diameter by studying adsorption kinetic of phenol and methylene blue aqueous solutions. Due to comparable surface chemistry of the templated samples, only their difference of porosity was considered as a decisive factor for the kinetics of adsorption. The relative role of each porosity was evidenced and quantified. It was found that mesopores are crucial for a fast transport of adsorptive into the adsorption sites (micropores/smaller mesopores) while the additional presence of macropores further accelerates the rate of sorption for both adsorptives.
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      PubDate: 2018-06-22T15:03:53Z
       
  • Multifunctional luminescent Cd (II)-based metal-organic framework material
           for highly selective and sensitive sensing 2,4,6-trinitrophenol (TNP) and
           Fe3+ cation
    • Abstract: Publication date: December 2018
      Source:Microporous and Mesoporous Materials, Volume 272
      Author(s): Jinson Hu, Tingting Cheng, Shengju Dong, Chunhui Zhou, Xinhua Huang, Lei Zhang
      Two multifunctional luminescent Cd(II)-MOFs materials, namely {[Cd3(BPDPE)(BDC)3·(DMF)2]2·DMF·2H2O} n (1) and {[Cd(BPDPE)(NDC)·(H2O)]·(H2O)} n (2) (BPDPE = 4,4′-bis(pyridy)diphenyl ether, H2BDC = 1,4-benzenedicarboxylate, H2NDC = 2,6-naphthalenedicarboxylic acid), were synthesized and systematically characterized. Complex 1 possesses a 3D structure constructed by BPDPE and BDC2− linking nonlinear trinuclear secondary building units [Cd3(COO)6], while complex 2 reveals a 2D wave-like sheet assembled by BPDPE linking [Cd(NDC)]n chain, the adjacent sheets interact each other by various H-bondings. Photoluminescence measurement revealed that complex 1 exhibits stronger emission peak by comparison of organic ligands, thereby serving as a promising candidate for fluorescent sensing materials. It is surprising find that complex 1 can highly sensitive fluorescent sense 2, 4, 6-trinitrophenol (TNP) through luminescence quenching effect. In addition, complex 1 shows highly sensitive fluorescent sensing for Fe3+ cation than for other metal ions. Furthermore, the quenching mechanisms of complex 1 as multifunctional sensors have been studied.
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      PubDate: 2018-06-22T15:03:53Z
       
  • EMT-type zeolite for deep purification of trace polar-oxygenated compounds
           from light olefins
    • Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): Yongxian Zhou, Wei Chen, Pengfei Wang, Yimin Zhang
      Pure EMT-type zeolite (EMC-2) was synthesized using 18-crown-6 ether as structure direction agent and first applied for deeply purification the trace polar-oxygenated compounds from light olefins as well as studying the removal mechanism. This EMC-2 zeolite crystals exhibited high crystallinity, regular hexagonal platelet morphology mainly with diameter of 3–4 μm, thickness of 350 nm. The N2 adsorption/desorption analyzer indicated the EMC-2 zeolite had both micropores and inter-particle mesopores. The BET surface area, total pore volume and average pore size were 599.5 m2/g, 0.347 cm3/g and 2.32 nm, respectively. By dynamic adsorption experiment at room temperature, the results demonstrated that the EMC-2 zeolite could deeply purify the trace polar-oxygenated compounds to below 1 × 10−6 mol/mol in N2 or C2H4 flow, and exhibited more excellent purification performance than that of 13X zeolite. The breakthrough time for methanol to 1.18 g EMC-2 zeolite was 73.0 h in N2 system, and 6.0 h to 0.31 g EMC-2 zeolite in C2H4 system. The cumulative adsorption amounts of EMC-2 zeolite for methanol and propanal in N2 and C2H4 system were 55.99 mg/g, 113.93 mg/g and 98.17 mg/g, 171.61 mg/g, respectively. Moreover, the regeneration experiment also demonstrated the EMC-2 zeolite had more stable structure and longer lifetime. The in-situ FTIR spectra indicated both the purification processes of EMC-2 zeolite for methanol and propanal were physi-sorption mainly via the interaction between the oxygen lone-pair electrons of impurities and the Na+ of EMC-2 zeolite. Therefore, the EMC-2 zeolite had great potentials for future industrial application of trace polar-oxygenated compounds removal from light olefins.
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      PubDate: 2018-06-22T15:03:53Z
       
  • Porous 10- and 12-vertex (bi)-p-dicarba-closo-boranedicarboxylates of
           cobalt and their gas adsorptive properties
    • Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): Ishtvan Boldog, Michal Dušek, Tomáš Jelínek, Petr Švec, Francisca Solânea de O. Ramos, Aleš Růžička, Roman Bulánek
      Two new porous coordination polymers, [Co3(μ3-OH)(Bcb10DC)2.5(DEF)3(EtOH)1.5(H2O)0.5] · DEF · EtOH (3b) and [Co2(Bcb12DC)2(DMF)4(EtOH)] · 2EtOH (4) based on 10- and 12-vertex p-bicarboranedicarboxylic acids, 1,1′-bi-(1,10-dicarba-closo-decaborane)-10,10′-dicarboxylic acid (H2Bcb10DC) and 1,1′-bi-(1,12-dicarba-closo-decaborane)-12,12′-dicarboxylic acid (H2Bcb12DC) were synthesized. Their properties were compared with the two known analogues based on shorter ligand-homologues, [Co(cb10DC)(DMF)] (1) and [Co4(OH)2(cb12DC)3(DMF)2(H2O)4] · 3DMF · EtOH (2). The structure of 3b is based on a trinuclear cluster and has a 3D structure with a 5-c bnn underlying net, while 4 is based on a binuclear cluster and composed of stacked 2D sql layers. Activated 3′ with altered structure has SBET(N2) of 1012 m2 g−1 and 4′ with mostly retained structure 920 m2 g−1. Gas adsorption by 3′ and 4′ at 1 bar is: 80.1 cm3 g-1 (0.72%wt) and 81.3 cm3 g-1 (0.73%wt) H2 at 77 K; 16.7 and 21.9 cm3 g-1 CO2 at 273 K; 6.2 and 10.0 cm3 g-1 of CH4 at 273 K. The isosteric heat of adsorption Qst at zero coverage are respectively: 5.0 and 4.5  kJ mol−1 for H2, 16.7 and 21.9 for CO2; 6.2 and 10.0 for CH4. 2′ with ∼645 m2 g−1 (calc. 883 m2g−1) has the highest mass-specific H2 adsorption, >30% than other compounds, while Qst is close to 1′ and slightly higher than for 3′ and 4´. Adsorption of CO2 and CH4 and Qst are ∼1.5–2 times lower for 3′ and 4′ compared to 1′ and 2´. The surface area specific adsorption of H2, CO2 and CH4 is the highest for 1´. The CO2/CH4 IAST selectivities (0.15/0.85; 1 bar, 298 K) are in 2–4.5 range. 3′ and 4′ retain a significant part of porosity after soaking in water unlike 1′ and 2´.
      Graphical abstract image

      PubDate: 2018-06-22T15:03:53Z
       
  • Hollow mesoporous heterostructures negative electrode comprised of
           CoFe2O4@Fe3O4 for next generation lithium ion batteries
    • Abstract: Publication date: December 2018
      Source:Microporous and Mesoporous Materials, Volume 272
      Author(s): Gopalu Karunakaran, Manab Kundu, Govindhan Maduraiveeran, Evgeny Kolesnikov, Mikhail V. Gorshenkov, Suresh Kannan Balasingam, Shilpa Kumari, Manickam Sasidharan, Denis Kuznetsov
      Hollow structured mixed metal oxides (MMOs) with porous outer shell have recently been emerged as advantageous candidates for energy conversion and storage applications due to their outstanding electrochemical properties. In this report, the novel bi-component-active hollow CoFe2O4@Fe3O4 nanospheres with the mesoporous outer shells (HCFO-POS) were successfully prepared by ultrasonic spray pyrolysis method. The as-synthesized HCFO-POS was evaluated as an anode material for lithium-ion battery (LIB), it exhibits excellent electrochemical properties for lithium storage. To be specific, it can deliver a decent specific capacity of 365 mAh g−1 even at a high current density of 1000 mA g−1 with cycling stability up to 500 cycles. The aforementioned excellent performance of this HCFO-POS electrode can be explained based on i) unique mesoporous nature which could buffer the volume change, shorten the diffusion path of Li+ ions during the lithiation/delithiation process, enhances the effective contact area between electrolyte/electrode interface and finally. ii) synergistic effect of mixed metal oxides which helps to improve the conductivity of the electrode.
      Graphical abstract image

      PubDate: 2018-06-19T19:19:11Z
       
  • Hydrothermal synthesis of needle-like nanocrystalline zeolites from
           metakaolin and their applications for efficient removal of organic
           pollutants and heavy metals
    • Abstract: Publication date: December 2018
      Source:Microporous and Mesoporous Materials, Volume 272
      Author(s): Hongwei Luo, Wei Wee Law, Yichao Wu, Weiping Zhu, En-Hua Yang
      In this study, an environment-friendly and sustainable route to convert clay minerals into highly efficient sorbents for organic pollutants and heavy metals removal was reported. Needle-like nanocrystalline zeolites were hydrothermally synthesized from metakaolin (MK) and their properties and efficiency for organic pollutants and heavy metals removal were investigated. After hydrothermal treatment, the morphology of metakaolin markedly transformed from layered structures to aggregations of needle-like zeolites, thereby resulting in substantial increases of total and meso porosities, N2 sorption capacity and specific surface area. The hydrothermally synthesized MK-based zeolites exhibited much stronger sorption capacity toward aniline (AN), 3-chloroaniline (3-CA), and humic acid (HA). The electrostatic attraction and surface complexation dominated by chemisorption likely accounted for the enhanced sorptive interactions between zeolites and organic compounds. Similarly, the adsorption capacity of the newly formed zeolites toward Cu(II) and Pb(II) increased almost 20-fold, which was 431.0 mg g−1 for Cu(II) and 337.8 mg g−1 for Pb(II). Ionic exchange reactions between heavy metal ions and the enriched sodium ion resulted in heavy metal removal by the MK-based zeolites. Thus, the hydrothermally synthesized MK-based zeolites may be employed as sorbents for wastewater treatment to remove organic pollutants and heavy metals with no significant toxicity risk.
      Graphical abstract image

      PubDate: 2018-06-19T19:19:11Z
       
  • Investigation of the acidic nature of MCM-68 zeolite based on the
           adsorption of CO and bulky probe molecules
    • Abstract: Publication date: December 2018
      Source:Microporous and Mesoporous Materials, Volume 272
      Author(s): Satoshi Inagaki, Sungsik Park, Hiroshi Yamazaki, Junko N. Kondo, Yoshihiro Kubota
      The aluminosilicate MCM-68 has an MSE topology, a unique pore system, and solid acid characteristics. For these reasons, it has potential applications as a highly efficient catalyst for paraffin cracking, methanol-to-olefin/dimethyl ether-to-olefin reactions, and the alkylation of aromatic compounds. In this work, the acidic properties of both the parent MCM-68 and dealuminated versions were evaluated using infrared spectroscopy in conjunction with the adsorption of CO and/or 2,4,6-trimethylpyridine (collidine). Notably, the relatively bulky collidine molecules could not enter the 12-ring pore-mouths of the MCM-68 at room temperature but were able to do so at 403 K, due to the excitation of pore-mouth breathing vibrations that allowed increased diffusion at higher temperatures. During CO adsorption study, two types of Lewis acid sites and one type of Brønsted acid sites were identified on the parent MCM-68. After dealumination by acid treatment, the Brønsted and stronger Lewis acid sites, especially those on the external surfaces of the MCM-68 particles, were preferentially removed.
      Graphical abstract image

      PubDate: 2018-06-19T19:19:11Z
       
  • An indirect approach for encapsulation of chiral cobalt catalyst in
           microporous Zeolite-Y
    • Abstract: Publication date: December 2018
      Source:Microporous and Mesoporous Materials, Volume 272
      Author(s): Mukesh Sharma, Biraj Das, Anil Hazarika, N.S.V.M. Rao Mangina, Galla V. Karunakar, Kusum K. Bania
      Hierarchical structure in microporous zeolite-Y was introduced to overcome the diffusional restriction for direct encapsulation of chiral cobalt (II) Schiff base complexes. Mesopores with cylindrical channels of ∼5 nm dimensions were formed on post modification of zeolite-Y and was evident from the transmission electron microscopy and surface area analysis. Two different chiral cobalt (II) Schiff base complexes with minor variation in the ligand structure were constructed inside the mesoporous zeolite-Y cavity. The formation of the metal complexes was ascertained from the decrease in surface area and mesoporous pore volume. The two synthesized heterogeneous chiral cobalt Schiff base complexes were used as catalysts for asymmetric Henry reaction. At −35 °C, more than 80% ee with S-major nitro-aldol product was achieved within 3 h. Initial activation of the reaction mixture with microwave irradiation was found to have dramatic influence on the catalytic performance of the two catalysts.
      Graphical abstract image

      PubDate: 2018-06-19T19:19:11Z
       
  • 3D printed mesoporous bioactive glass/metal-organic framework scaffolds
           with antitubercular drug delivery
    • Abstract: Publication date: December 2018
      Source:Microporous and Mesoporous Materials, Volume 272
      Author(s): Peng Pei, Zhengfang Tian, Yufang Zhu
      Three-dimensional (3D) porous scaffolds with sustained drug delivery are pursued for osteoarticular tuberculosis therapy after surgery. In this study, mesoporous bioactive glass/metal-organic framework (MBG/MOF) scaffolds with sustained antitubercular drug release have been fabricated by 3D printing. The results showed that the MBG/MOF scaffolds possess macropores of ca. 400 μm and enhanced compressive strength of 3–7 MPa, also exhibited good biocompatibility and apatite forming ability in vitro. Furthermore, the drug release rate and pH microenvironment of the MBG/MOF scaffolds could be controlled due to the MOF degradation. These results indicated that the 3D printed MBG/MOF scaffolds are promising for treating osteoarticular tuberculosis.
      Graphical abstract image

      PubDate: 2018-06-19T19:19:11Z
       
  • Porous crumpled graphene with hierarchical pore structure and high surface
           utilization efficiency for supercapacitor
    • Abstract: Publication date: December 2018
      Source:Microporous and Mesoporous Materials, Volume 272
      Author(s): Zhihong Tang, Xiaodong Li, Tianren Sun, Shuling Shen, Xiu Huixin, Junhe Yang
      As a promising active material for supercapacitor, graphene suffers serious restack, which reduces the surface area utilization of electrodes. Porous crumpled graphene (PCG) with hierarchical pore structure is designed in this paper. The spherical morphology of porous crumpled graphene effectively prevents it from restack, and thus dramatically promotes the utilization of pores on the graphene sheets. As electrode in supercapacitor, the specific capacitance per surface area is as high as 20.7 μF cm−2 due to the high surface utilization efficiency, which is much higher than that of the traditional activated carbon (6.0 μF cm−2) and porous graphene (6.5 μF cm−2), approaching the theoretical value of 20.9 μF cm−2.
      Graphical abstract image

      PubDate: 2018-06-19T19:19:11Z
       
  • Homogeneous thin coatings of zeolitic imidazolate frameworks prepared on
           quartz crystal sensors for CO2 adsorption
    • Abstract: Publication date: December 2018
      Source:Microporous and Mesoporous Materials, Volume 272
      Author(s): Lilian Sarango, Javier Benito, Ignacio Gascón, Beatriz Zornoza, Joaquín Coronas
      Thin films of four zeolitic-imidazolate frameworks (ZIF-8, ZIF-67, ZIF-7, and ZIF-93) have been fabricated by a dip-coating method on glass and quartz crystal microbalance (QCM) substrates. Homogeneous coatings with sizes of crystals of 65 ± 20, 285 ± 96, 61 ± 20 and 72 ± 21 nm for ZIF-8, ZIF-67, ZIF-7, and ZIF-93, respectively, were obtained. Upon characterization of the ZIFs and coatings by XRD, TGA, SEM, FTIR, contact angle measurement and N2 adsorption, the coatings were exposed to vapors of dichloromethane for activation. The CO2 adsorption of the coatings was then studied using a QCM device.
      Graphical abstract image

      PubDate: 2018-06-19T19:19:11Z
       
  • Micro-structure change of polycrystalline FAU zeolite membranes during a
           hydrothermal synthesis in a dilute solution
    • Abstract: Publication date: December 2018
      Source:Microporous and Mesoporous Materials, Volume 272
      Author(s): Izumi Kumakiri, Yukichi Sasaki, Wataru Shimidzu, Kouji Hashimoto, Hidetoshi Kita, Takeo Yamaguchi, Shin-ichi Nakao
      Faujasite (FAU) zeolite membranes were prepared by seed growth method. The polycrystalline zeolite membrane became less porous with the growth of zeolite crystals. The microstructure of the membrane was characterized by SEM and TEM after several rates of crystal growth. In addition, Si/Al ratio was analysed by TEM-EDS. Meso-voids existed in the zeolite membrane after 1-h synthesis, and hexagonal shaped FAU crystals were easily distinguished. Twin relations were quite often observed for the connection between FAU crystals, while they were seldom found in the seed crystals. On the other hand, crystals lost hexagonal shape with further synthesis time. Moreover, the density of twin relations became less. While voids could hardly being observed by SEM in the zeolite membrane, there existed intercrystalline boundaries formed by two crystals of different orientation. Microstructures of these boundaries were directly observed by HREM. Si/Al ratio of the zeolite membrane was close to 1, which is smaller than that of seed crystals (Si/Al = 2.5). Step growth at the twin boundary was firstly observed. This growth process is assumed to be the key growth mechanism in densification of the polycrystalline zeolite membrane. Finally, densification process of zeolite membrane is proposed based on the microscopic analysis.
      Graphical abstract image

      PubDate: 2018-06-19T19:19:11Z
       
  • Durability of silica aerogels dedicated to superinsulation measured under
           hygrothermal conditions
    • Abstract: Publication date: December 2018
      Source:Microporous and Mesoporous Materials, Volume 272
      Author(s): Bruno Chal, Geneviève Foray, Bernard Yrieix, Karine Masenelli-Varlot, Lucian Roiban, Jean-Marc Chenal
      Energy efficiency in buildings is a crucial lever for lowering greenhouse gas emissions and a mass market for silica aerogel as retrofitting material. Their durability is therefore a major concern. When applying the precautionary principle, industrial companies have difficulties in estimating the service lifetime of innovative materials such as aerogel. Thus, their costs remain high and market penetration low until the durability of the materials they produce is confirmed. In this paper, commercial silica aerogels were exposed to accelerated ageing over long periods. Microstructural evolutions were tracked by nitrogen and water sorption while thermal conductivities were characterized by heat fluxmeter measurements. 96 and 384 days at 70 °C and 90%RH were sufficient to produce noticeable changes in the physico-chemical properties of certain products but almost none in others. The first change observed was an increase of hydrophilicity, followed by a loss of specific surface area, and a shifted and enlarged pore size distribution. The measurements confirmed that microstructure changes induce higher thermal conductivities. Depending on the specific type of aerogel product, the accelerated ageing tests lead to a significant, but limited increase of thermal conductivity of up to 2,5 mW/(m.K). The main hypotheses for explaining this phenomenon are the growth of neck size between two silica particles and the presence of water in the pores. In addition, it is shown for the first time for a wide range of aerogels that pore size distribution and hydrophobization are the key parameters for tuning aerogel durability in severe conditions. Consequently, the mesoporous community has a framework of tests and mechanisms to design aerogels for their specific efficiency/cost/durability requirements.
      Graphical abstract image

      PubDate: 2018-06-19T19:19:11Z
       
  • The adsorption kinetics of CO2 on copper hexacyanoferrate studied by
           thermogravimetric analysis
    • Abstract: Publication date: December 2018
      Source:Microporous and Mesoporous Materials, Volume 272
      Author(s): Dickson O. Ojwang, Jekabs Grins, Gunnar Svensson
      The CO2 adsorption and CO2 adsorption kinetics were evaluated by thermogravimetry on two Prussian blue analogues, K2x/3CuII [FeII x FeIII 1-x (CN)6]2/3, with nominally K-free x = 0.0 and K-rich x = 1.0. Differential isosteric heats of adsorption were determined from adsorption isotherms using the Clausius-Clapeyron equation and integral values by differential scanning calorimetry. The average differential heats of CO2 adsorption are 28 kJ/mol for x = 0.0 and 33 kJ/mol for x = 1.0. Both compositions show small maxima in differential heat at ∼1 mmol/g. The integral adsorption heats were determined to be 26 kJ/mol for both x = 0.0 and x = 1.0. The kinetic CO2 adsorption/desorption curves can be modeled by a double exponential function describing two parallel processes with different rate constants. The activation energies for CO2 adsorption on x = 0.0 were 6 (1) kJ/mol for the faster component and 16 (1) kJ/mol for the slower one, while the corresponding values for x = 1.0 were 9 (1) kJ/mol and 7 (1) kJ/mol, respectively. The maximum CO2 uptake for both compositions was found to be ∼4.5 mmol/g, 19.8 wt %, at 1 bar and 273 K. The materials exhibited fast adsorption kinetics and stable cyclic performance at room temperature. The kinetics were slower for the samples with x = 1.0 than for x = 0.0 which may be attributed to interactions between CO2 molecules and K+ ions.
      Graphical abstract image

      PubDate: 2018-06-19T19:19:11Z
       
  • Nickel catalysts supported on silica microspheres for CO2 methanation
    • Abstract: Publication date: December 2018
      Source:Microporous and Mesoporous Materials, Volume 272
      Author(s): Wojciech Gac, Witold Zawadzki, Grzegorz Słowik, Andrzej Sienkiewicz, Agnieszka Kierys
      Nickel catalysts supported on silica microspheres were prepared by the application of porous resin beads (Amberlite XAD7HP) as hard template using different order of nickel nitrate and tetraethoxysilane (TEOS) introduction. Large nickel oxide nanoparticles distributed over silica microspheres were formed when nickel precursor was introduced directly to the polymer template prior to the silica framework development or added into the silica-polymer composites. On the other hand, an impregnation of as-prepared silica microspheres after template removal led to the formation of small nickel oxide nanoparticles. The catalysts showed hierarchical pore structure. Low-temperature nitrogen adsorption/desorption and photoacoustic Fourier-transform infrared spectroscopy studies revealed slight changes of porosity and surface properties of catalysts affected by the synthesis methods. X-ray diffraction, scanning and transmission electron microscopy, temperature-programmed reduction and hydrogen desorption studies were used for determination of the properties of metallic nickel nanoparticles. It was stated that the activity and selectivity of catalysts in the CO2 methanation reaction was related to the active surface area and the size of nickel nanoparticles. An increase in CO2 conversion and selectivity to methane at low temperatures (220–350 °C) with an increase in active surface area and decrease in nickel crystallite size was observed.
      Graphical abstract image

      PubDate: 2018-06-19T19:19:11Z
       
  • N-doping and ultramicroporosity-controlled crab shell derived carbons for
           enhanced CO2 and CH4 sorption
    • Abstract: Publication date: December 2018
      Source:Microporous and Mesoporous Materials, Volume 272
      Author(s): Hee Soo Kim, Min Seok Kang, Seunghun Lee, Yong-Woo Lee, Won Cheol Yoo
      Highly N-doped crab shell-derived carbon nanofibers (CSCNs) with enhanced sorption capacity for CO2 and CH4 are presented. Two different carbonization temperatures, 600 °C and 900 °C were utilized to control the N-doping level of the CSCNs; the N-content of CSCN processed at 600 °C is higher than that processed at 900 °C. After judicious activation process to fine-tune ultramicroporosity (<1 nm) by hot CO2 treatment, the CSCN obtained from 600 °C with the most developed ultramicroporosity showed higher CO2 uptake capacity compared to that of CSCN carbonized at 900 °C due to higher N-doping level, although the ultramicroporosity of the two samples is similar. In contrast, similar CH4 sorption capacities were identified for these samples. In addition, very efficient and selective separation of CO2/N2 was achieved from CSCN carbonized at 600 °C with maximum ultramicroporosity; meanwhile, similar selective separations of CH4/N2 were observed for both of the most activated CSCNs. As a result, the relationship between the ultramicroporosity and CO2 and CH4 uptake capacities, and N-doping effect are clearly elucidated.
      Graphical abstract image

      PubDate: 2018-06-19T19:19:11Z
       
  • Regulation of the surface area and surface charge property of MOFs by
           multivariate strategy: Synthesis, characterization, selective dye
           adsorption and separation
    • Abstract: Publication date: December 2018
      Source:Microporous and Mesoporous Materials, Volume 272
      Author(s): Tian-Tian Li, Yi-Min Liu, Tao Wang, Ying-Lin Wu, Yong-Lin He, Rui Yang, Sheng-Run Zheng
      By using multivariate strategy, a series of multivariate UiO-66-type metal−organic frameworks with mixed 1,4-benzendicarboxylic acid (BDC) and 1,2,4,5- benzentetracarboxylic acid (BTC) ligands in different ratio, namely UiO-66-n (COOH)2 (n = 0, 0.25, 0.50, 0.75 and 1), had been successfully prepared. The products were characterized by 1H NMR, powder X-ray diffraction, field emission scanning electron microscopy, thermogravimetric analysis, N2 adsorption-desorption, and zeta potential. It can be observed that with the increase of BTC ratio, the surface area decreases from 1620 to 179 cm3/g, and the zeta potential decreases from 36.11 to −29.78 mV. Therefore, this strategy can effectively regulate the surface area and charge of the frameworks, thereby regulate their adsorption behaviors towards selected dye molecules. In contrast to the pristine UiO-66 that only adsorption anionic dyes, the multivariate MOFs shows an excellent selective dye adsorption to cationic dyes, where the adsorption capacities of MB and RhB on UiO-66-0.25(COOH)2, UiO-66-0.50(COOH)2, and UiO-66-0.75(COOH)2 are 87, 90, 94 mg/g and 84, 47, 46 mg/g, respectively. In addition, the selective adsorption to mixed cationic and anionic dyes (MB and MO) and cationic dyes with different size (MB and RhB) were also achieved by UiO-66-0.25(COOH)2 and UiO-66-0.75(COOH)2, respectively. This adsorption selectively is attribute to the electrostatic attraction between the charged surface of MOFs and the dyes, as well as the surface area of the MOFs.
      Graphical abstract image

      PubDate: 2018-06-19T19:19:11Z
       
  • Formic acid modulated (fam) aluminium fumarate MOF for improved isotherms
           and kinetics with water adsorption: Cooling/heat pump applications
    • Abstract: Publication date: December 2018
      Source:Microporous and Mesoporous Materials, Volume 272
      Author(s): How Wei Benjamin Teo, Anutosh Chakraborty, Sibnath Kayal
      This article presents the synthetization and characterisation of fam (formic acid modulated) Al Fum (aluminium fumarate) MOFs. The parent Al Fum MOFs are modulated with 5 ml, 10 ml and 15 ml of formic acid for comparison purposes. The characteristics of newly developed fam Al Fum are presented by TEM and PXRD analyses. N2 volumetric adsorption is performed to evaluate the porous properties of fam Al Fum. It is found that Al Fum particles start to elongate with the addition of formic acid and the synthesis duration is greatly reduced. An increase in micro pores distribution is observed for 10 ml of formic acid added to the parent Al Fum MOFs. Water adsorption isotherms and kinetics are measured by a gravimetric analyser. It is found that fam Al Fum MOFs improve the water vapour uptake rates as compared with the parent Al Fum. The addition of 10 ml formic acid into Al Fum MOF shows the best performances in terms of uptake-offtake difference (Δq), which is 12.5% higher than that of the parent Al Fum MOF. The isosteric heat of adsorption is also calculated. The improved isotherms and kinetics results indicate fam Al Fum as potential adsorbent for heat transmission applications.
      Graphical abstract image

      PubDate: 2018-06-19T19:19:11Z
       
  • Curcumin polymer coated, self-fluorescent and stimuli-responsive
           multifunctional mesoporous silica nanoparticles for drug delivery
    • Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): Xiubin Xu, Shaoyu Lü, Can Wu, Zhiyong Wang, Chen Feng, Na Wen, Mingzhu Liu, Xinyu Zhang, Zhen Liu, Yongqi Liu, Chunzhen Ren
      We reported the facile preparation of self-fluorescent mesoporous silica nanoparticles based on a triple-role curcumin polymer shell as stimuli-responsive multifunctional nanocarriers for drug delivery. This curcumin polymer shell integrates multiple function of acting as fluorescent agents, increasing the drug loading ratio of curcumin, and controlling the open and close of the pores in a “smart” way. This novel drug nanocarrier will inspire the development of smart and self-fluorescent drug nanocarrier to achieve imaging and therapeutic goals for cancer therapy.
      Graphical abstract image

      PubDate: 2018-06-19T19:19:11Z
       
  • Y zeolite-supported niobium pentoxide catalysts for the glycerol
           acetalization reaction
    • Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): C. Ferreira, A. Araujo, V. Calvino-Casilda, M.G. Cutrufello, E. Rombi, A.M. Fonseca, M.A. Bañares, I.C. Neves
      Faujasite zeolite-supported niobium-based catalysts (with Nb2O5 amounts of 5 and 15 wt%) were prepared by impregnation of NaY, HY, and HUSY zeolites using a niobum(V) ammonium oxalate complex. These obtained Nb-containing catalysts were calcined and thoroughly characterized by different physico-chemical techniques. The characterization results revealed that niobium oxide was successfully loaded on the surface of the zeolite supports without any significant modification of the faujasite structure. Surface area and pore volume were found to decrease with the increase in the Nb content for all the prepared catalysts. The presence of Nb was proved to increase the hydrophobicity of the zeolites and to affect surface acidity. The catalytic activity of the Nb-containing samples was evaluated in the glycerol acetalization reaction, and the Nb-HUSY catalysts were found to show the best catalytic performance.
      Graphical abstract image

      PubDate: 2018-06-19T19:19:11Z
       
  • Oxidative dehydrogenation of ethylbenzene over CMK-1 and CMK-3 carbon
           replicas with various mesopore architectures
    • Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): Sebastian Jarczewski, Marek Drozdek, Piotr Michorczyk, Carlos Cuadrado-Collados, Jesus Gandara-Loe, Joaquín Silvestre-Albero, Piotr Kuśtrowski
      Nanoreplication strategy was used for the synthesis of mesoporous ordered carbon materials with various pore architectures and surface compositions. Two different silica templates (regular MCM-48 and hexagonal SBA-15) were filled with a carbon precursor – poly(furfuryl alcohol) or sucrose – by the precipitation polycondensation or incipient wetness impregnation, respectively. Furthermore, the resulting carbon precursor/silica composites were carbonized at various temperatures from the range of 650–1050 °C. It was shown that the carbon precursor and method of its deposition strongly influenced structural and textural parameters of the final carbon material determined by XRD, low-temperature N2 adsorption and TEM. The specific surface area of the sucrose-based CMK-3 was ca. 45% higher than the poly(furfuryl alcohol)-derived replicas. On the other hand, this effect was not observed for CMK-1 replicas. The carbonization temperatures tuned up the content of C=O moieties on the surface of carbon replica calculated based on temperature-programmed desorption (TPD) profiles. Obviously, the concentration of C=O functionalities was correlated to the catalytic activity in the oxidative dehydrogenation of ethylbenzene (EB) to styrene. Nevertheless, the CMK-1 replicas were more sensitive to the C=O concentration in terms of EB conversion. Hence, we discussed carefully the role of the pore geometry in the catalytic performance of the studied carbon materials. For the CMK-1 and CMK-3 carbon replicas with comparable chemical and textural properties, but different pore structure, the initial EB conversion varied considerably, reaching 34.2% and 21.6%, respectively, at 350 °C and EB/O2 ratio = 1.0.
      Graphical abstract image

      PubDate: 2018-06-19T19:19:11Z
       
  • From a naturally occurring-clay mineral to the production of porous
           ceramic membranes
    • Authors: Abdelaziz Elgamouz; Najib Tijani
      Abstract: Publication date: 15 November 2018
      Source:Microporous and Mesoporous Materials, Volume 271
      Author(s): Abdelaziz Elgamouz, Najib Tijani
      A silicalite clay composite membrane was produced by hydrothermal deposition using tetraethyl orthosilicate (TEOS) as silica source, tetra-n-propylammonium bromide (TPABr) as template and KOH as mineralizing agent. Silicalite was deposited in the mesopores and on the surface of porous ceramic membrane supports made from a naturally available clay mineral abundantly found in the central region of Morocco (Meknès). Three flat-disc membrane supports were prepared by uniaxial pressure on pure clay powder (AS), mixture of clay and activated carbon (5%, w/w) (AC) and mixture of clay and starch (20% w/w) (AA). The porosity of membrane supports was studied as function of the final calcination temperature. It was found that the mesopores contribution to porosity was 25%, however their contribution to the specific surface area is more than 90%. The mesopores structure was investigated. XRD confirms the formation of crystalline silicalite layers inside the mesopores of the clay flat-disc supports. Typical MFI-type zeolite morphology was confirmed by SEM. The scope and limitations of the membranes in terms of selectivity between SF6 and N2, is discussed.
      Graphical abstract image

      PubDate: 2018-06-01T02:54:46Z
       
 
 
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