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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 July 2016
      Source:Microporous and Mesoporous Materials, Volume 228




      PubDate: 2016-05-16T04:13:46Z
       
  • Sulfonic functionalized SBA-15 catalysts in the gas phase glycerol
           dehydration. Thermal stability and catalyst deactivation
    • Abstract: Publication date: August 2016
      Source:Microporous and Mesoporous Materials, Volume 230
      Author(s): B.O. Dalla Costa, M.S. Legnoverde, C. Lago, H.P. Decolatti, C.A. Querini
      The catalytic conversion of glycerol to acrolein was studied using sulfonic functionalized mesoporous silica SBA-15. The catalysts were prepared by the co-condensation method, conducting the silica synthesis and functionalization of its surface with thiol-propyl groups in the same stage. In a next step, the oxidation of thiol groups to sulfonic groups was made varying the concentration of H2O2 in order to obtain catalysts with different levels of acidity on the surface. The solids were characterized by BET, SEM, FTIR, XPS, and potentiometric titration with n-butilamine. The thermal stability was analyzed by thermogravimetry (TGA) and temperature-programmed desorption (TPD). The reaction tests were performed at different temperatures between 275 °C and 350 °C, and under feed flow conditions that allowed the study of the deactivation phenomena by coke deposition. The best temperature in order to maximize the acrolein yield was 300 °C. Higher temperatures led to a rapid deactivation by a combined effect of coke deposition and decomposition of functional groups.
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      PubDate: 2016-05-16T04:13:46Z
       
  • Insight into the PEG-linked bis-imidazolium bridged framework of
           mesoporous organosilicas as ion exchangers
    • Abstract: Publication date: August 2016
      Source:Microporous and Mesoporous Materials, Volume 230
      Author(s): Manish Kumar Dinker, Prashant Shripad Kulkarni
      Development of novel periodic mesoporous organosilicas (PMOs) were carried out by designing precursor, PEG-linked bis-imidazolium chloride bridged silsesquioxanes (PIMAILS, an ionic liquid). The involvement of tetraethyl ortho silicate (TEOS) as a template in an acidic medium led to the formation of a silica hybrid material (PMO-T). Contrary, in the absence of TEOS, PIMAILS self-assembled in a basic environment over the cationic surfactant, cetyl trimethyl ammonium bromide (CTAB) to form the silica hybrid material (PMO-S). The availability of surface silanols and ionic liquid (IL) in both the PMOs were verified using FT-IR and 13C solid NMR. Further, they were quantified using 29Si solid state NMR technique. The results depicted 3 times better loading of the precursor in the framework of PMO-S than PMO-T. Larger surface areas and higher porosities were found in PMO-S than PMO-T while analyzed using BET-BJH technique. Thermogravimetric (TG) analysis revealed nearly 2.2 times higher weight losses (%) from PMO-S than PMO-T, which validate the results of silica solid state NMR. Powder XRD analysis showed well-defined hkl reflections (110) and (200) from PMO-S in contrast of PMO-T, describing the periodic arrangement of IL within PMO-S. Finally ion-exchange capacities of these materials were estimated by employing them for recovery of W(VI). The PMO-S, which has higher percentage of IL in the framework, achieved better separation of W(VI) than PMO-T.
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      PubDate: 2016-05-16T04:13:46Z
       
  • Nitrogen doped mesoporous carbon aerogels and implications for
           electrocatalytic oxygen reduction reactions
    • Abstract: Publication date: August 2016
      Source:Microporous and Mesoporous Materials, Volume 230
      Author(s): Balázs Nagy, Silvia Villar-Rodil, Juan M.D. Tascón, István Bakos, Krisztina László
      Mesoporous carbon aerogels with 0–4% nitrogen content were prepared from 3D resorcinol (R) – melamine (M) – formaldehyde (F) aerogels by tuning the M/R ratio during the polymerization process. The carbon matrix obtained has a complex porosity. Although the surface area and pore volume are maintained, the pore volume from N2 adsorption decreases with increasing N content. Increasing the M/R ratio increases not only the N but also the O content of RMF based carbon samples. The O and N containing functional groups are less abundant on the surface than in the bulk. N occurs at the surface predominantly in form N-6 and N-Q. With increasing heteroatom concentration the carbon surface becomes less hydrophobic, but high amounts seem to reduce accessibility to the pores. The effect of N content on the catalytic performance in oxygen reduction reactions (ORR) was measured by cyclic voltammetry (CV). The onset potential approaches that of a PAN derived carbon in the sample with the highest N content. The strong correlation between the cathode current density and the BET surface area reveals the role of the accessibility of the N species in the electrocatalytic process.
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      PubDate: 2016-05-16T04:13:46Z
       
  • Sol-gel synthesis of mesoporous aluminosilicates with a narrow pore size
           distribution and catalytic activity thereof in the oligomerization of
           dec-1-ene
    • Abstract: Publication date: August 2016
      Source:Microporous and Mesoporous Materials, Volume 230
      Author(s): Marat R. Agliullin, Irina G. Danilova, Aidar V. Faizullin, Srgey V. Amarantov, Sergei V. Bubennov, Tatyana R. Prosochkina, Nelly G. Grigor’eva, Evgeny A. Paukshtis, Boris I. Kutepov
      Porous aluminosilicates with Si/Al ratio of 80 have been prepared by the sol-gel synthesis using tetraethyl orthosilicate (TEOS) and aluminum nitrate (Al(NO3)3*9H2O). It has been shown that the precipitation pH value and the gelation conditions strongly affected characteristics of the porous structure, the incorporation of aluminum into the silicate framework, and the surface acidity. It has been found that the implementation of the sol-gel synthesis initially in the acidic medium followed by the alkaline one allowed producing the mesoporous aluminosilicate with the specific surface area SBET of 660 m2 g− 1, the mesopore volume V of 0.74 cm3 g− 1, and the pore size distribution within the range of 2–5 nm. The high activity and selectivity of synthesized aluminosilicates in the oligomerization of dec-1-ene have been revealed. The conversion of dec-1-ene reached 92%. The formation selectivity of dec-1-ene oligomers with the oligomerization degree n = 2–3 amounted 87%.
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      PubDate: 2016-05-16T04:13:46Z
       
  • Self-diffusion of phosphonium Bis(Salicylato)Borate ionic liquid in pores
           of Vycor porous glass
    • Abstract: Publication date: August 2016
      Source:Microporous and Mesoporous Materials, Volume 230
      Author(s): Andrei Filippov, Nail Azancheev, Faiz Ullah Shah, Sergei Glavatskih, Oleg N. Antzutkin
      1H NMR pulsed field gradient was used to study self-diffusion of a phosphonium bis(salicylato)borate ionic liquid ([P6,6,6,14][BScB]) in the pores of Vycor porous glass at 296 K. Confinement in pores increases diffusion coefficients of the ions by a factor of 35. However, some [P6,6,6,14][BScB] ions demonstrated apparent diffusion coefficients much lower than their mean values, which may be due to partially restricted diffusion of the ions. We suggest that this fraction corresponds to areas where ions are confined by pore ‘necks’ (micropores) and empty voids. Heating of the ionic liquid/Vycor system at 330 K led to a change in the diffusivity of the ions, because of their redistribution in the pores. The size of the bounded regions is on the order of 1 μm, as estimated from the dependence of the ion diffusivity on the diffusion time.
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      PubDate: 2016-05-16T04:13:46Z
       
  • Thiol-functionalized polysiloxanes modified by lead nanoparticles:
           Synthesis, characterization and application for determination of trace
           concentrations of mercury(II)
    • Abstract: Publication date: August 2016
      Source:Microporous and Mesoporous Materials, Volume 230
      Author(s): Katarzyna Tyszczuk-Rotko, Ilona Sadok, Mariusz Barczak
      The paper presents the first report on preparation, characterization and application of a lead nanoparticles-modified thiol-functionalized polysiloxane film glassy carbon electrode (PbNPs-SH-PF/GCE). The surfactant-templated thiol-functionalized silica films were prepared in a one-pot evaporation-induced self-assembly process by co-condensation of tetraethoxysilane and 3-mercaptopropyltrimethoxysilane in the presence of cetyltrimethylammonium bromide. The porous silica thin films were modified by electroplated lead nanoparticles (in situ plating), which made it possible to significantly improve the electrochemical performance of SH-PF/GC electrodes. The structural and chemical information about modified and unmodified thiol-functionalized polysiloxanes was derived from the data of TEM-EDS, 29Si NMR, XPS analysis and nitrogen sorption measurements. The PbNPs-SH-PF/GCE was proven as an efficient tool in the determination of trace concentration of Hg(II) using square-wave anodic stripping voltammetry method. Under optimized conditions, the oxidation peak current is linear to the concentration of Hg(II) in the range of 0.001–1.0 μmol L−1. The detection limit with an accumulation time of 120 s is estimated to be 0.35 nmol L−1. In addition, the developed voltammetric procedure at the PbNPs-SH-PF/GCE was applied for determination of Hg(II) in certified reference material (1641 d), natural water samples collected from Bystrzyca and Vistula rivers, and the assay results were satisfactory.
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      PubDate: 2016-05-16T04:13:46Z
       
  • Significantly increasing porosity of mesoporous carbon by NaNH2 activation
           for enhanced CO2 adsorption
    • Abstract: Publication date: August 2016
      Source:Microporous and Mesoporous Materials, Volume 230
      Author(s): Kuan Huang, Song-Hai Chai, Richard T. Mayes, Shuai Tan, Christopher W. Jones, Sheng Dai
      Sodium amide (NaNH2), a readily available strong base, was investigated as an efficient reagent for chemical activation of mesoporous carbon (MC) in the temperature range of 400–900 °C, aiming to enhance the CO2 adsorption performance. Total surface area and pore volume of the activated MC increase greatly with the activation temperature up to 700 °C and then tend to level off. Small micropores with a diameter <1 nm are developed mainly at low temperatures (400–550 °C) and decrease continuously in volume as the activation temperature increases. Nitrogen species are incorporated onto the carbon activated at 400 °C but completely disappear at higher activation temperatures due to poor thermal stability. CO2 adsorption experiments illustrated a substantial improvement in capacities at 0 °C for the NaNH2-activated carbons (6.31 mmol/g at 1 bar and 2.06 mmol/g at 0.15 bar) in comparison to pristine MC (2.01 mmol/g at 1 bar and 1.00 mmol/g at 0.15 bar). The low-pressure CO2 capacities are well correlated with the volume of small micropores rather than the total micropore volume and surface area. The activation ability of NaNH2 was compared with those of KOH and NaOH, verifying the superiority of NaNH2 in the MC activation under relatively moderate conditions, i.e., activation reagent/MC weight ratio of two and activation temperature of 550 °C.
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      PubDate: 2016-05-16T04:13:46Z
       
  • Rapid and high yield synthesis method of colloidal nano faujasite
    • Abstract: Publication date: August 2016
      Source:Microporous and Mesoporous Materials, Volume 230
      Author(s): Bo Wang, Yanzuo Li, Chenrui Shao, Mengyi Cui, Prabir K. Dutta
      Conventional synthesis methods of isolated, colloidal nano faujasites (nanoFAU) have been limited by low yield (typically <10%) and long synthesis time (days). In this study, synthesis of colloidal nanoFAU by microwave heating and a recently reported dehydration/rehydration hydrothermal (DRHT) process is examined. All studies are done with a literature reported 3-day aged composition (Comp A, 0.048 Na2O: 2.40 (TMA)2O(2OH): 1.2 (TMA)2O(2Br): 4.35 SiO2: 1.0 Al2O3: 249 H2O, TMA+ is tetramethylammonium). Using this composition in a hydrothermal process, nanoFAU with 5% yield is obtained in 96 h. With microwave heating for 4 h, micron-sized zeolite A crystals and nanoFAU are formed with yields of 13% and 7%, respectively. With DRHT, nanoFAU of Si/Al ratio 2.23 is formed in 20 h with yield of 7%. It has been reported that supernatant of composition A after the hydrothermal process can be cycled with mid-synthesis addition of NaOH, resulting in yield of nanoFAU of 43% in 10 cycles in 576 h. A synthesis protocol involving 29 h of continuous DRHT process with mid-synthesis addition of NaOH over 6 cycles produced nanoFAU with a yield of 93%, average particle size of 29 ± 7 nm, as measured by TEM, a Si/Al ratio of 1.76, and surface area of 625 m2/g. Practical implications, like cost and TMA+ removal for the reported synthesis method is also included.
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      PubDate: 2016-05-16T04:13:46Z
       
  • Modification of Y Faujasite zeolites for the trapping and elimination of a
           propene-toluene-decane mixture in the context of cold-start
    • Abstract: Publication date: August 2016
      Source:Microporous and Mesoporous Materials, Volume 230
      Author(s): A. Westermann, B. Azambre, M. Chebbi, A. Koch
      The modification of a HY zeolite (with Si/Al ratio = 2.5) by impregnation with a platinum salt or ion exchange with Cu2+ cations was carried out in order to evaluate the potential interest of the obtained materials as hydrocarbon traps for cold-start application. Textural, structural and chemical characterizations were carried out using N2 adsorption isotherms at −196 °C, XRD and DRIFTS of adsorbed CO and NO. Acidic properties of the parent H/Y and Cu- and Pt-modified zeolites were determined using FTIR of adsorbed pyridine. The methodology used to investigate the adsorption behaviour of the parent and modified HY zeolites consisted in: (i) analysing qualitatively and quantitatively the breakthrough curves obtained at 35 °C during the adsorption of a ternary hydrocarbon mixture (propene, toluene, decane) as well as the data from subsequent temperature-programmed experiments (TPD under He or TPSR in presence of 10%O2 or 10%O2/0.2%NO) (ii) establishing relationships between adsorption/reactivity data and the structural, textural and chemical properties of the modified zeolites. Namely, the introduction of copper and platinum species considerably improves the adsorption of unsaturated hydrocarbons, such as propene or toluene, at the expense of decane. This results in a more adequate balance between all the hydrocarbons adsorbed, which is required for cold-start application. In addition, Cu/Y and Pt/Y zeolites were also found to be efficient for the removal of NOx or HC total oxidation, respectively.
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      PubDate: 2016-05-16T04:13:46Z
       
  • Effect of hydration and dehydration on the properties of SBA-15 layer
           studied by humidity scanning QCM-D
    • Abstract: Publication date: August 2016
      Source:Microporous and Mesoporous Materials, Volume 230
      Author(s): Yana Znamenskaya, Sebastian Björklund, Vitaly Kocherbitov, Viveka Alfredsson
      Surface deposited layers of mesoporous silica particles could function as support for bio-sensing or drug release applications. It is crucial to control the surface deposition process and employ relevant techniques to characterize the properties of the particles on the surface. Here, we deposit SBA-15 particles on native silica or cationic surfaces and characterize the hydration and dehydration by employing a novel method based on humidity scanning quartz crystal microbalance with dissipation (HS QCM-D). SBA-15 platelets are deposited with mesopores oriented parallel to the surface normal using drop deposition. SEM shows a monolayer on the surface, which is established as stable. Water sorption-desorption isotherms of the SBA-15 layer from HS QCM-D are compared with isotherms from water sorption calorimetry and nitrogen sorption on bulk material. We demonstrate that HS QCM-D provides results in good agreement with results obtained with the reference methods. The properties of SBA-15 particles are retained during the deposition process and unaffected by the presence of the surface. In addition, HS QCM-D is a fast technique that requires significantly lower amount of material (∼5000 times) compared to experiments on bulk material. HS QCM-D provides complete characterization of the pore size distribution of SBA-15.
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      PubDate: 2016-05-16T04:13:46Z
       
  • A new kinetic model for absorption of oil spill by porous materials
    • Abstract: Publication date: August 2016
      Source:Microporous and Mesoporous Materials, Volume 230
      Author(s): Maryam Khosravi, Saeid Azizian
      A new kinetic model has been presented, based on combination of linear driving force and fractal like approaches, for correct modeling of oil spill absorption by porous material. The derived kinetic equation is able to describe maximum capacity of porous material and diffusion coefficient of oil into pores. In this new model, the presence of various pores with different sizes is considered, accounting for real systems. The basis of this new model is the presence of different pores with different diffusion coefficients and also changes of pores filling with time based on their sizes. The presented equation has been used for kinetic modeling of oil spill absorption by different porous materials, very well.
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      PubDate: 2016-05-10T02:20:47Z
       
  • On the general water harvesting capability of metal-organic frameworks
           under well-defined climatic conditions
    • Abstract: Publication date: August 2016
      Source:Microporous and Mesoporous Materials, Volume 230
      Author(s): F. Trapani, A. Polyzoidis, S. Loebbecke, C.G. Piscopo
      The ability of some highly porous materials to adsorb and desorb water vapor under atmospheric conditions without the use of external power sources could become a promising methodology for the capture and release of water in arid or desert regions of the world. Here, the use of some readily available metal-organic frameworks as water harvesting materials has been tested and compared with other porous materials. Water adsorption experiments were conducted at 25 °C and at a relative humidity (RH) of 40%, while the desorption process took place at 45 °C with a RH of 10%. These experimental conditions are in good accordance with the climatic conditions being present in the Sahara desert during the summer season. In all experiments, UiO-66 derived MOFs showed the best water harvesting efficiency, releasing up to 89% of the adsorbed water at 45 °C and 99% at 60 °C. Though, the adsorption capacity of UiO-66 is noticeably lower than that of more hydrophilic materials such as the MOF compound HKUST-1 and the zeolite A3. The latter, however, are only able to release water when they are heated up to at least 60 °C. Finally, the stability of the investigated MOFs after adsorption-desorption cycles have been confirmed through XRD and FT-IR analyses.
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      PubDate: 2016-05-10T02:20:47Z
       
  • Amine-functionalized mesoporous silica KIT-6 as a controlled release drug
           delivery carrier
    • Abstract: Publication date: 15 July 2016
      Source:Microporous and Mesoporous Materials, Volume 229
      Author(s): Mohamad M. Ayad, Nehal A. Salahuddin, Ahmed Abu El-Nasr, Nagy L. Torad
      Mesoporous silica KIT-6, has been prepared through the sol-gel method followed by a chemical modification using 3-aminopropyl triethoxysilane (APTS) to obtain KIT-6-NH2 as a drug delivery carrier. The mesostructure properties was fully characterized by transmission electron microscope (TEM), N2 sorption isotherm, Fourier transform infrared (FT-IR), low-angel X-ray diffraction (XRD) and small-angel x-ray scattering (SAXS). Loading of ketoprofen (KP) and 5-flurouracil (5-FU) drugs as models into KIT-6 and KIT-6-NH2 was studied using quartz crystal microbalance (QCM) and UV–visible spectroscopy. The loading uptake and release behaviors of KP and 5-FU were highly dependent on the textural properties of KIT-6 and KIT-6-NH2. The release of drugs was carefully studied in simulated gastric fluid (pH 2) and in simulated intestinal fluid (pH 7.4). First order, Higuchi, Hixson–Crowell and Korsmeyer–Peppas release kinetic models were applied to the experimental data and the release was found to obey a first-order rate kinetic.
      Graphical abstract image

      PubDate: 2016-05-10T02:20:47Z
       
  • Building concept inspired by raspberries: From microporous zeolite
           nanocrystals to hierarchically porous assemblies
    • Abstract: Publication date: 15 July 2016
      Source:Microporous and Mesoporous Materials, Volume 229
      Author(s): Michael Klumpp, Lintao Zeng, Shaeel A. Al-Thabaiti, Alfred P. Weber, Wilhelm Schwieger
      Hierarchically porous zeolites offer great potential in catalytic and sorptive processes due to the enhanced mass transport properties by the increased diffusivity of the molecules from the bulk phase to the final active sites or sorption sites, respectively. In this contribution we present a simple, 3-step bottom-up preparation route yielding binder-free spherical zeolite material exhibiting a hierarchical pore system. This process consists of zeolite synthesis, aggregation and recrystallization. In this contribution, the process is demonstrated on silicalite-1 (MFI-type zeolite) as a model system. The aggregation process was realized by special spray drying of a complete reaction mixture containing pre-synthesized nanocrystals. The spray drying process results in spherical aggregates which contain amorphous silica species originating from the unconverted part of the zeolite synthesis mixture and which are acting as an intermediate binder. Steam-assisted crystallization was then applied to convert these amorphous species into crystalline zeolite enabling the overall process to utilize 100% of the initial silicon from the zeolite synthesis mixture.
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      PubDate: 2016-05-10T02:20:47Z
       
  • Adsorption in heterogeneous porous media: Hierarchical and composite
           solids
    • Abstract: Publication date: 15 July 2016
      Source:Microporous and Mesoporous Materials, Volume 229
      Author(s): Ludovic Deliere, Francois Villemot, David Farrusseng, Anne Galarneau, Sylvain Topin, Benoit Coasne
      Experiment and molecular simulation are used to investigate adsorption in heterogeneous porous media consisting of hierarchical solids (combining different porosity scales) or composite solids (such as silver nanoparticles adsorbed at the external surface of zeolite). It is shown that adsorption in such heterogeneous materials can be written as a linear combination of the adsorption isotherms in its different domains (i.e. porosity scales for the hierarchical sample and constituents for the composite sample). In the case of the composite material, we also show that the linear combination can be used with weighing parameters obtained for a different adsorbate. Such a superimposition principle, which is validated using well-characterized experimental samples, is of interest for characterization purpose as well as industrial applications as they can be used to determine accurately the amount of phases in a given sample (volume corresponding to a given porosity scale or constituent). In contrast, significant departure between the experimental adsorption isotherm and the linear combination can be used to detect coupling effects between the different domains or restrained access to a given domain type. Such a characterization strategy of complex heterogeneous media is complementary to other experiments, such as those probing capillary hysteresis shapes, scanning curves and subloops, which allow determining the distribution of domains within the framework of the independent domain theory.
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      PubDate: 2016-05-10T02:20:47Z
       
  • An investigation on the effect of KMnO4 on the pore characteristics of
           pistachio nut shell based activated carbon
    • Abstract: Publication date: August 2016
      Source:Microporous and Mesoporous Materials, Volume 230
      Author(s): Fatemeh Tavakoli Foroushani, Hossein Tavanai, Farzaneh Ali Hosseini
      This paper investigates the effect of KMnO4 pretreatment on the pore characteristics of activated carbon (AC) prepared from pistachio shell precursor though oxidation stabilization, carbonization and activation. Moreover, the pore characteristics of the ACs produced in this research are compared with the counterparts produced by other researchers. AC has a wide range of applications as filtering media in waste water treatment and gas purification. The yield of the produced AC samples lies in the range of 17.89%–28.97%. SEM micrographs show very interesting and very well organized repeating patterns for the ACs. It was found that the higher the exposure time, the lower was the surface area of the AC samples. The pores in the AC samples are considered as mesopore with diameter in the range of 8 nm–15 nm. The pores of the pistachio shell based ACs reported in the literature are basically of micro type with a size of less than 3 nm. It is concluded that oxygen stabilization plays an important role in determining the size of the pores during pyrolysis. The bigger size of the pores leads to a lower surface area and very high total pore volume. XRD patterns indicate the presence of high degree of crystallinity consisting of very small crystallites in the ACs produced. This is also supported by the Raman analysis. FTIR analysis proved the disappearance of groups such as carbonyl, ether and esters after the conversion of raw pistachio shells into AC.
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      PubDate: 2016-05-10T02:20:47Z
       
  • A facile fabrication of highly b-oriented MFI zeolite films in the
           TEOS-TPAOH-H2O system without additives
    • Abstract: Publication date: August 2016
      Source:Microporous and Mesoporous Materials, Volume 230
      Author(s): Xiaofei Lu, Yong Peng, Zhengbao Wang, Yushan Yan
      A facile secondary growth method for fabrication of highly b-oriented MFI zeolite films is demonstrated. This method enables the growth of b-oriented MFI seed monolayers into highly b-oriented dense films in the TEOS-TPAOH-H2O system without any additive or extra treatment. Suppression of twin growth is achieved via the increase of water content in the synthesis solution. A clear correlation between the film orientation and the synthesis composition for secondary growth is presented. Compared with previously reported strategies in controlling the orientation of MFI zeolite films, this method offers greater operating window of the synthesis composition (H2O/Si = 1500–3000, TPA+/Si = 0.1–0.5, OH−/Si = 0.1–0.2) and synthesis condition (150–180 °C, 4–8 h). The thickness of b-oriented MFI films (370 nm-610 nm) can be tuned by adjusting the water amount or the synthesis condition. The new synthesis method uses lower amount of organic template and silica source making it potentially more economical and environmentally friendly and thus attractive for industrial implementation.
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      PubDate: 2016-05-10T02:20:47Z
       
  • On the drastic reduction of organic structure directing agent in the
           steam-assisted crystallization of zeolite with hierarchical porosity
    • Abstract: Publication date: August 2016
      Source:Microporous and Mesoporous Materials, Volume 230
      Author(s): Mita Rilyanti, Rino R. Mukti, Grandprix T.M. Kadja, Masaru Ogura, Hadi Nur, Eng-Poh Ng, Ismunandar
      The absence of organic structure directing agent (OSDA) in the synthesis of zeolite has shown progress recently, nevertheless the formation mechanism is still not clearly understood and the technique cannot be fully generalized for the synthesis of various types of zeolite frameworks. In this research, the drastic reduction of OSDA in the synthesis of ZSM-5 employing the steam-assisted crystallization (SAC) was studied. The used tetrapropylammonium bromide as OSDA in the synthesis of ZSM-5 was one-fifth and one-twentieth of typical amount reported in literature. Upon OSDA reduction, the crystallization leads to the formation of ZSM-5 with hierarchical pore structure revealed by SEM and TEM images in which it is different compared to the parent spherical-like crystal morphology of ZSM-5 synthesized without reducing the OSDA amounts. A quantitative analysis of the X-ray diffractograms suggests that 100% crystallinity could not be achieved in the sample synthesized under the OSDA reduction confirming that the orientation of crystal growth is not similar to the conventional coffin-type ZSM-5 crystal. The deviancy in crystal growth is further associated with the formation of mesopores originated from severe defect planes of ZSM-5. On the verge of gradual disappearance, a broadened distribution of mesoporosity could return the crystallinity to 100% in which faulty elongated crystal shape, close to typical coffin-type growth orientation appeared as the product after commencing the Oswald ripening of longer period of synthesis time. The conventional hydrothermal synthesis may not be used for crystallizing ZSM-5 when the OSDA was one-twentieth of typical starting amount making the SAC to be an appropriate technique for synthesizing ZSM-5 under drastically reduced OSDA, in particular to simultaneously perform the hierarchically porous zeolite.
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      PubDate: 2016-05-10T02:20:47Z
       
  • Development of sepiolite/SiC porous catalytic filters for diesel soot
           abatement
    • Abstract: Publication date: August 2016
      Source:Microporous and Mesoporous Materials, Volume 230
      Author(s): F.E. Tuler, R. Portela, P. Ávila, J.P. Bortolozzi, E.E. Miró, V.G. Milt
      Honeycomb monoliths made up of 70 wt.% sepiolite and 30 wt.% SiC were prepared and macropores were generated in the honeycomb structure by introducing a temporary additive with the aim of obtaining an adequate porosity to use the structures prepared as diesel soot filters (DPF). CLARIMEX activated carbon was the most suitable among the additives studied. In order to generate wall-flow type filters, it was also necessary to investigate suitable materials to alternatively plug the channels of the honeycomb monolith, finding that refractory mortar finely milled and mixed with water formed a paste easy to apply, which adhered firmly to the walls of the monolith being thermally and mechanically resistant. The incorporation of Co and Ce as active phases was performed by successive impregnation followed by calcination at 600 °C. This system presented satisfactory results with respect to the maximum temperature of soot combustion rate, which is in the range of the diesel exhaust gases temperature (300–450 °C). The wall-flow catalytic monoliths developed have similar characteristics to commercial diesel particulate filters in spite of having 70 wt.% of natural clay in its composition. The pore size remains to be further modulated in order to achieve a better permeation flow, similar to that of commercial filters, which could be tried out using larger particle size activated carbons.
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      PubDate: 2016-05-10T02:20:47Z
       
  • 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
       
  • Diffusion mediated selective adsorption of Zn2+ from artificial seawater
           by MCM-41
    • Abstract: Publication date: 15 July 2016
      Source:Microporous and Mesoporous Materials, Volume 229
      Author(s): Aneesh Mathew, Surendran Parambadath, Su Yeon Kim, Hyung Min Ha, Chang-Sik Ha
      MCM-41 can play a pivotal role as a host material for adsorption applications. In this work, MCM-41 was found to be 100% selective for Zn2+ from artificial seawater containing Ni2+, Li+, Co2+, Cd2+ and Zn2+ as hetero ions. The pristine and Zn2+ ions adsorbed MCM-41 (Zn@MCM-41) were well characterized by various spectroscopic techniques. The selective Zn2+ ion adsorption property of MCM-41 remained intact irrespective of the concentration of Zn2+ ions. The adsorption property of MCM-41 was unaffected by the synthesis strategy of MCM-41. SBA-15 exhibited 85 and 15% mole selectivity for Zn2+ and Cd2+ ions, respectively, under similar experimental conditions. This highlights the unique property of MCM-41 for the selective adsorption of Zn2+ ions from artificial seawater. TEM, FTIR and XPS analysis confirmed the presence of Zn2+ ions in Zn@MCM-41. The protection using methyl group on the outer/both surfaces of MCM-41 (Me-MCM-41/MeS-MCM-41) disclosed the necessity of interaction between silica surface and metal ion for selective adsorption of Zn2+ ions. The detailed investigation of adsorption mechanism postulates that the selective adsorption of Zn2+ ions by MCM-41 was achieved only in the presence of sodium chloride, which is the major component of artificial seawater. An adsorbed amount of 12 mg g−1 was observed for Zn2+ ions even in presence of Cd2+ ions, while both of the ions possess similar chemical characteristics.
      Graphical abstract image

      PubDate: 2016-05-05T07:54:54Z
       
  • Self-diffusion of heptane inside aggregates of porous alumina particles by
           pulsed field gradient NMR
    • Abstract: Publication date: 15 July 2016
      Source:Microporous and Mesoporous Materials, Volume 229
      Author(s): Evan M. Forman, Matthias A. Trujillo, Kirk J. Ziegler, Steven A. Bradley, Haiyan Wang, Sesh Prabhakar, Sergey Vasenkov
      1H and 13C pulsed field gradient (PFG) NMR was used to study the self-diffusion of heptane in porous alumina exhibiting a hierarchy of pore sizes that cover the range from micropore to macropore sizes. Diffusion measurements were performed for the lengths scales of displacements comparable with and smaller than the sizes of aggregates of porous alumina particles. The measured heptane diffusivities inside the particle aggregates were found to be several times smaller than the diffusivity in the bulk liquid heptane. The diffusivities inside the aggregates were correlated with the aggregate structural characteristics, which include pore volume, pore size and packing density of the individual particles in the aggregates.
      Graphical abstract image

      PubDate: 2016-05-05T07:54:54Z
       
  • Optimization, modeling and characterization of sol-gel process parameters
           
    • Abstract: Publication date: 15 July 2016
      Source:Microporous and Mesoporous Materials, Volume 229
      Author(s): Murat Efgan Kibar, Orhan Özcan, Yeşim Dusova-Teke, Esra Yonel-Gumruk, Ayşe Nilgün Akin
      A response surface methodology (RSM) was implemented to investigate the effect of sol-gel synthesis variables in the structural and textural properties of boron doped alumina synthesis. The effects of four independent operating variables (mol HNO3/mol AIP, concentration of AIP, mol H2O/mol AIP, and boron weight/total catalyst support weight) were explored on the responses, namely the total surface area, and the BJH desorption pore diameter of boron doped alumina (B-Al2O3) supports. The variables were optimized and the models were validated by the experimental runs which were synthesized by simultaneously adjusting the operating variables giving maximum deviation of 3.3% from the desired value. The synthesized samples were characterized by XRD, BET, SEM, ICP-OES and TEM techniques. The characterization studies pointed out the interactions between process variables significantly affect the morphology of the catalyst support. The morphology of the supports can be modified from cracked surface to nano-sphere formation by the introduction of boron.
      Graphical abstract image

      PubDate: 2016-05-05T07:54:54Z
       
  • Storage and delivery of nitric oxide by microporous titanosilicate ETS-10
           and Al and Ga substituted analogues
    • Abstract: Publication date: 15 July 2016
      Source:Microporous and Mesoporous Materials, Volume 229
      Author(s): Moisés L. Pinto, Ana Cristina Fernandes, Fernando Antunes, João Pires, João Rocha
      Exogenous administration of nitric oxide may be a therapy for several pathologies because this molecule regulates many biological systems. Here, the storage and release of NO by microporous titanosilicate ETS-10 and samples where the silicon was substituted by aluminium (ETAS-10) or gallium (ETGS-10) are studied. The Al- and Ga-doped materials exhibit an increase in the storage capacity of 95% and 55%, respectively, the highest values observed, so far, for microporous titanosilicates. ETAS-10 releases more NO and ETGS-10 almost the same amount as ETS-10. In ETAS-10 and ETGS-10, the irreversibly adsorbed NO amount increases relatively to ETS-10. Tests of NO release in haemoglobin solutions indicate that biologically relevant amounts are release and that ETS-10 and ETGS-10 display a release slower than ETAS-10, more adequate for a sustained delivery. Cytotoxicity studies show that the samples have very low toxicity (cell viability above 87%, after 72 h) at high concentration (0.45 mg cm−3). Tests at variable ETS-10 concentration further confirm the low cytotoxicity of this material, even at high concentrations (up to 1.8 mg cm−3).
      Graphical abstract image

      PubDate: 2016-04-28T01:55:24Z
       
  • Bifunctional periodic mesoporous organosilicas with sulfide bridges as
           effective sorbents for Hg(II) extraction from environmental and drinking
           waters
    • Abstract: Publication date: 15 July 2016
      Source:Microporous and Mesoporous Materials, Volume 229
      Author(s): Mustafa Imamoglu, Damián Pérez-Quintanilla, Isabel Sierra
      A well-ordered two-dimensional hexagonal periodic mesoporous organosilica have been prepared with a high content of disulfide groups in the pore wall (PMO-S-S). This material was obtained by co-condensation of bis(triethoxysylilpropyl)disulfide and tetraethyl orthosilicate under acidic conditions, using non-ionic surfactant P123 as the template. In order to obtain bifunctional disulfide-bridged materials (PMO-S-S-MTTZ and PMO-S-S-MP), the PMO-S-S was modified in a second step with the organic derivatives of 5-mercapto-1-methyltetrazole (MTTZ) or 2-mercaptopyridine (MP) with sulphur and nitrogen active groups in their molecular structures. The characterization of the materials was carried out by XRD, TEM and SEM, nitrogen adsorption-desorption isotherms, 13C MAS-NMR, 29Si MAS-NMR, FTIR, elemental and thermogravimetric analysis. All prepared materials showed excellent adsorption efficiency and selectivity for Hg(II). The results confirmed the existence of additional active sulphur and nitrogen groups on the material surface, in addition to the disulfide groups of the framework, gave a significant enhancement of Hg(II) maximum adsorption capacity of the materials, being the highest Hg(II) adsorption capacity obtained 437 mg g−1 at pH 5. The prepared materials could be potential sorbents for the extraction of this heavy metal from environmental and drinking waters.
      Graphical abstract image

      PubDate: 2016-04-28T01:55:24Z
       
  • Titania-silica monolithic multichannel microreactors. Proof of concept and
           fabrication/structure/catalytic properties in the oxidation of
           2,3,6-trimethylphenol
    • Abstract: Publication date: 15 July 2016
      Source:Microporous and Mesoporous Materials, Volume 229
      Author(s): Agnieszka Koreniuk, Katarzyna Maresz, Klaudia Odrozek, Julita Mrowiec-Białoń
      Titania-silica monoliths with 3D hierarchical porosity in μm and nm scales were fabricated using either direct or post-synthesis method, to find that they enable very fast continuous-flow oxidation of 2,3,6-trimethylphenol to 2,3,5-trimethyl-1,4-benzoquinone with hydrogen peroxide as the oxidant. Extensive characterization of the monoliths using N2 adsorption, mercury porosimetry, SEM, energy dispersive X-ray mapping, FT-IR and UV–Vis spectroscopy showed a strong impact of the fabrication method on the structural properties and also coordination/dispersion of the titanium ions incorporated into the silica. Systematic study of the monolithic microreactors and corresponding powders in the continuous-flow and batch systems, revealed a large complexity of performance/structure/catalytic properties relationships. A direct method resulted in titanium active centres highly dispersed in microporous skeleton, and therefore larger TOF, compared to the surface titanium entities in monoliths obtained from the post-synthesis approach. However, owing to the lower porosity and much smaller flow-through (macro)pores the pressure drops were almost two orders of magnitude larger. The highly porous monolithic microreactors fabricated by the post-synthesis incorporation of titanium appeared to be superior; the substrate conversions of 85% were obtained in about 12 min compared to those of ca. 75% obtained in batch systems after 1 h. This could be explained by very intensive mass transport in macro- and mesopore size scales.
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      PubDate: 2016-04-28T01:55:24Z
       
  • Polyethyleneglycol grafting of y-alumina membranes for solvent resistant
           nanofiltration
    • Abstract: Publication date: 15 July 2016
      Source:Microporous and Mesoporous Materials, Volume 229
      Author(s): Cheryl R. Tanardi, Romina Catana, Mihai Barboiu, André Ayral, Ivo F.J. Vankelecom, Arian Nijmeijer, Louis Winnubst
      A method is presented for grafting mesoporous γ-alumina (pore size 5 nm), supported on an α-alumina ceramic membrane, with polyethylene glycols (PEG). The grafting performance of γ-Al2O3 powders with various PEG grafting agents, having different molecular weights, alkoxy groups, and ureido functionality, was analyzed by TGA, 29Si-NMR, FTIR, and the BET method. FTIR analysis indicated that grafting has occurred. It was found that the molecular weight, the presence of an ureido functionality and the number of hydrolyzable groups of the grafting agents influenced the grafting density. The highest grafting density in this work was obtained by using a silylated ureido PEG with the shortest chain length (n = 10), while the number of alkoxy groups of the grafting agents influenced the structural configuration of the grafted moiety. The grafted membrane surface showed a hydrophilic character. A decrease in solvent permeation of both ethanol and hexane after grafting was observed, due to the presence of the grafted moiety inside the membranes reducing the membrane pore diameter. The permeability with respect to different types of solvents (polar and nonpolar) was investigated. Lower permeability of ethanol than hexane was observed accompanied by a higher retention of Sudan Black in ethanol than in hexane. This effect is explained by the difference in solvent sorption in the grafted moiety for different types of permeating solvents.
      Graphical abstract image

      PubDate: 2016-04-28T01:55:24Z
       
  • In vitro stimulation of MC3T3-E1cells and sustained drug delivery by
           a hierarchical nanostructured SiO2CaOP2O5 scaffold
    • Abstract: Publication date: 15 July 2016
      Source:Microporous and Mesoporous Materials, Volume 229
      Author(s): M. Lourdes Ramiro-Gutiérrez, Leonor Santos-Ruiz, Sara Borrego-González, José Becerra, Aránzazu Díaz-Cuenca
      A hierarchical scaffold, SP1_h_HA, consisting of a biomimetic nano-hydroxyapatite surface coating growth onto a reticulated structure having a nano-organized porous texture was fabricated and functionally studied in vitro using osteoprogenitor cells. Three scaffold materials (designated as SP0_l, SP0_h and SP1_h) were also prepared through modifications of the processing variables as control materials. The scaffolds were characterized showing well-interconnected micron-sized voids and a nano (4–6 nm)-organized porosity. In order to evaluate potential local risks and performance over mammalian cells the scaffolds were studied in comparison with a commercial clinical grade scaffold material, ProOsteon® 500R. MC3T3-E1 pre-osteoblast viability was evaluated using the resazurin assay and field emission gun scanning electron microscopy (FEG-SEM), showing in all cases good proliferative response. Alkaline phosphatase (ALP) production and analysis of the differentiation marker osteocalcin (OC), both in non-osteoinductive and osteoinductive media, were assessed using colorimetric and RT-PCR methods. The implementation of the new scaffold processing variables enhanced ALP activity with respect to the SP0_l control material. The cell proliferation, ALP activity, and mRNA OC expression response to SP1_h_HA scaffold were higher than those observed after the use of ProOsteon® 500R. In addition, SP1_h_HA scaffold showed a two stage sustained release of gentamicin sulfate (GS) instead of the quick release shown by ProOsteon® 500R. These results suggest that our synthesized scaffold could be effective for antibiotic delivery and bone regeneration and a better option than ProOsteon® 500R.
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      PubDate: 2016-04-24T02:05:32Z
       
  • Synthesis of mesoporous geopolymers containing zeolite phases by a
           hydrothermal treatment
    • Abstract: Publication date: 15 July 2016
      Source:Microporous and Mesoporous Materials, Volume 229
      Author(s): N.K. Lee, Hammad R. Khalid, H.K. Lee
      The present study investigates the synthesis of mesoporous geopolymers containing different nano-crystalline zeolite phases. A hydrothermal treatment procedure was utilized to synthesize the mesoporous geopolymers using fly ash, slag and alkaline solution. The effects of slag addition and molar ratio of alkaline solution on the microstructure and mechanical strength of the geopolymers were investigated and evidenced by XRD analysis, compressive strength and nitrogen adsorption tests. The test results showed that the geopolymers incorporating fly ash and slag consisted of Na-P1 and Sodalite zeolite phases, and had the characteristic of mesoporous materials (2 nm < pore size < 50 nm) in which capillary condensation may occur. The highest compressive strength of the geopolymers was 16.57 MPa, and the desired mesoporous characteristics were met by adding 20% slag content to fly ash and adopting the hydrothermal process at a relatively low temperature. The highest BET surface area and single point adsorption pore volume of the mesoporous geopolymers were 114.16 m2/g and 0.2677 cm3/g, respectively.
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      PubDate: 2016-04-24T02:05:32Z
       
  • Effect of catalyst loading on hydrogen storage capacity of ZIF-8/graphene
           oxide doped with Pt or Pd via spillover
    • Abstract: Publication date: 15 July 2016
      Source:Microporous and Mesoporous Materials, Volume 229
      Author(s): Hu Zhou, Jian Zhang, Dong Ji, Aihua Yuan, Xiaoping Shen
      In this work, a series of zeolitic imidazolate framework (ZIF-8)/graphene oxide (GO) supported Pt or Pd nanoparticles (NPs) with different loading amounts were obtained via a simple liquid impregnation of ZIF-8/GO with metal salt solution followed by a reduction treatment. Powder X-ray diffraction, Fourier transform infrared spectra, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, inductively coupled plasma-emission spectroscopy, and nitrogen adsorption-desorption measurements were employed to investigate the physical and chemical properties of as-prepared samples. The Pt and Pd particles in the corresponding composites have average diameters of about 4.5 and 4.6 nm, respectively. All metal-doped ZIF-8/GO composites maintained the host framework of pure ZIF-8, although their specific surface areas were significantly reduced. The introduction of metal catalysts into the ZIF-8/GO matrix does not favor the hydrogen adsorption performance at 77 K due to the physisorption mechanism. In contrast, the adsorption isotherms at 298 exhibited dramatically improved storage capacities, by factors of 3.8–11.8 (Pt-doped ZIF-8/GO) and 7.9–12.6 (Pd-doped ZIF-8/GO) times over pristine ZIF-8 at the hydrogen pressure of 860 mmHg. This enhancement is mainly attributed to the spillover mechanism by metal catalysts into the ZIF-8/GO support. More importantly, the effect of catalysts dispersion and content on the level of hydrogen storage was also explored, which showed that the composites with the most homogeneous metal distribution and moderate loading amount would display the highest hydrogen adsorption performance.
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      PubDate: 2016-04-24T02:05:32Z
       
  • Radiofrequency controlled release from mesoporous silica nano-carriers
    • Abstract: Publication date: 15 July 2016
      Source:Microporous and Mesoporous Materials, Volume 229
      Author(s): Marek Šoltys, Pavel Kovačík, Miloslav Lhotka, Pavel Ulbrich, Aleš Zadražil, František Štěpánek
      Composite porous silica-iron oxide nanoparticles with the ability to store chemical payloads and release them upon triggering a radiofrequency field were prepared. The particle structure consisted of a hollow porous silica core, covered with a layer of iron oxide nanoparticles bound to the silica surface by electrostatic forces. The particle size distribution, morphology, porosity and stability was systematically studied together with their sorption capacity and heating properties under the effect of a radiofrequency magnetic field. It was observed that the particles are able to achieve a heat dissipation rate of nearly 200 W/g, which was high enough for using the radiofrequency field as a trigger mechanism for the remote release (desorption) of a chemical payload from the particles.
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      PubDate: 2016-04-24T02:05:32Z
       
  • Incorporation of Ni into HZSM-5 zeolites: Effects of zeolite morphology
           and incorporation procedure
    • Abstract: Publication date: 15 July 2016
      Source:Microporous and Mesoporous Materials, Volume 229
      Author(s): Yadolah Ganjkhanlou, Elena Groppo, Silvia Bordiga, Mariia A. Volkova, Gloria Berlier
      Insertion of Ni species into H-ZSM5 catalysts with high Si/Al ratio (around 50) and different morphology (micron sized particles vs nanosheet ones) has been carried out by two different methods, namely impregnation and ion exchange routes. The resultant samples have been characterized by IR spectroscopy using CO as probe molecule after thermal treatment in oxygen or vacuum. In all samples different Ni2+ surface sites (counterions, grafted or on the surface of NiO particles) have been observed, but their distribution and concentration were found to be greatly influenced by morphology of zeolite particles as well as Ni incorporation method. For instance, the nanosheet morphology was found to favour ion exchange, probably in relation to high amount of surface tetrahedral Al sites. Moreover, a small fraction of sites was found to be reduced, both to Ni+ counterions and Ni0 (nano) particles, when the activation was carried out in vacuum in some of the samples. This could be related to changes in the population of surface OH groups (Brønsted sites and hydrogen bonded silanols), and to the formation of surface defects (strained SiOSi bridges). These observations give indications about the mechanism governing ion reactivity and migration in zeolite matrices, and confirm the fact that silanol groups are of the utmost importance in affecting the dispersion of the metal phase, and therefore the corresponding redox properties.
      Graphical abstract image

      PubDate: 2016-04-24T02:05:32Z
       
  • Dative and covalent-dative postsynthetic modification of a two-fold
           interpenetration pillared-layer MOF for heterogeneous catalysis: A
           comparison of catalytic activities and reusability
    • Abstract: Publication date: 15 July 2016
      Source:Microporous and Mesoporous Materials, Volume 229
      Author(s): Zahra Saedi, Vahid Safarifard, Ali Morsali
      Two MOF-supported Mo(VI) oxidation catalysts bearing N,O-chelating ligand were synthesized via dative and covalent-dative postsynthetic modifications of a two-fold interpenetration pillared-layer amine-functionalized MOF known as TMU-16-NH2. These post-functionalized catalysts were characterized by FT-IR spectroscopy, thermogravimetric analysis, ICP and X-ray powder diffraction techniques. The Mo(VI)-containing MOFs exhibit both epoxide selectivity and fully reusability for alkenes epoxidation by tert-butylhydroperoxide (TBHP).
      Graphical abstract image

      PubDate: 2016-04-24T02:05:32Z
       
  • Zinc ferrites hosted in activated carbon from waste precursors as
           catalysts in methanol decomposition
    • Abstract: Publication date: 15 July 2016
      Source:Microporous and Mesoporous Materials, Volume 229
      Author(s): Tanya Tsoncheva, Alexandra Mileva, Daniela Paneva, Daniela Kovacheva, Ivanka Spassova, Diana Nihtianova, Pavel Markov, Nartzislav Petrov, Ivan Mitov
      Activated carbons from peach stones and waste polyolefin wax were prepared and tested as a host matrix of nanodispersed zinc ferrite. Nitrogen physisorption, Boehm method, XRD, TPR with hydrogen, FTIR, UV–Vis and Moessbauer spectroscopy were applied to investigate the activated carbon characteristics and the state of loaded on it metal oxide particles. The higher microporosity and lower surface functionality, typical of activated carbon from waste biomass, facilitated the formation of more finely dispersed, located into the micropores iron and zinc oxide nanoparticles. This promoted formation of Zn rich ferrite phase which ensures high catalytic activity in methanol decomposition.
      Graphical abstract image

      PubDate: 2016-04-24T02:05:32Z
       
  • Increasing mesoporosity by a silica hard template in a covalent organic
           polymer for enhanced amine loading and CO2 capture capacity
    • Abstract: Publication date: 15 July 2016
      Source:Microporous and Mesoporous Materials, Volume 229
      Author(s): HaYeon Lee, Cafer T. Yavuz
      Solid sorbents for chemisorptive carbon dioxide uptake in post-combustion scenarios require strong binding groups like amines. Post-synthetic impregnation of reactive amines requires large pore volumes. Covalent organic polymers (COPs) are microporous (or narrow mesoporosity) network polymers with physisorptive behavior. Herein as the first of such attempt in porous organic polymers, we modified COP-1, which is an inexpensive, scalable porous polymer for effective amine loading. By expanding the pore of COP-1 through hard templation by silica, the surface area and pore volume are increased by 2.3 and 2.9 times, respectively. It was shown that the increase of pore volume was mostly from pores larger than 5 nm and it correlates well with the silica particle size (12 nm) and the inter-particle pore sizes of silica (31 nm). As a result, amine impregnated Si-COP-1 adsorbs CO2 with the increase of 2.44 at 273 K and 4.06 times at 298 K (at flue gas relevant partial pressure of 0.15 bar) over the parent COP-1. Our results show the possibility of tuning porosity for developing industrially feasible CO2 capturing sorbents.
      Graphical abstract image

      PubDate: 2016-04-24T02:05:32Z
       
  • Controlled release of alendronate from nitrogen-doped mesoporous carbon
    • Abstract: Publication date: 15 July 2016
      Source:Microporous and Mesoporous Materials, Volume 229
      Author(s): Dipendu Saha, Amanda Spurri, Jihua Chen, Dale K. Hensley
      We have synthesized a nitrogen doped mesoporous carbon with the BET surface area of 1066 m2/g, total pore volume 0.6 cm3/g and nitrogen content of 0.5%. Total alendronate adsorption in this carbon was ∼5%. The release experiments were designed in four different media with sequential pH values of 1.2, 4.5, 6.8 and 7.4 for 3, 1, 3 and 5 h, respectively and at 37 °C to imitate the physiological conditions of stomach, duodenum, small intestine and colon, respectively. Release of the drug demonstrated a controlled fashion; only 20% of the drug was released in the media with pH = 1.2, whereas 64% of the drug was released in pH = 7.4. This is in contrary to pure alendronate that was completely dissolved within 30 min in the first release media (pH = 1.2) only. The relatively larger uptake of alendronate in this carbon and its sustained fashion of release can be attributed to the hydrogen bonding between the drug and the nitrogen functionalities on carbon surface. Based on this result, it can be inferred that this formulation may lower the side effects of oral delivery of alendronate.
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      PubDate: 2016-04-24T02:05:32Z
       
  • Well-dispersed gold nanoparticles anchored into thiol-functionalized
           hierarchically porous materials for catalytic applications
    • Abstract: Publication date: 15 July 2016
      Source:Microporous and Mesoporous Materials, Volume 229
      Author(s): Yang Xu, Tianqi Wang, Zidong He, Aiqing Zhong, Kun Huang
      In this work, we demonstrate a novel method that enables the fabrication of thiol-functionalized hierarchically porous materials (SH-HPMs) by combination of hyper-cross-linking and molecular templating of core-shell bottlebrush copolymers. Well-dispersed gold (Au) nanoparticles with an average size of 3.0 nm, synthesized by in situ reduction of HAuCl4, were then anchored into the SH-HPMs support, which showed remarkable catalytic performances on the reduction reaction of 4-nitrophenol.
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      PubDate: 2016-04-24T02:05:32Z
       
  • Static in-situ hydrothermal synthesis of small pore zeolite SSZ-16 (AFX)
           using heated and pre-aged synthesis mixtures
    • Abstract: Publication date: 1 July 2016
      Source:Microporous and Mesoporous Materials, Volume 228
      Author(s): P. Hrabanek, A. Zikanova, T. Supinkova, J. Drahokoupil, V. Fila, M. Lhotka, H. Dragounova, F. Laufek, L. Brabec, I. Jirka, B. Bernauer, O. Prokopova, V. Martin-Gil, M. Kocirik
      The conditions of static in-situ hydrothermal synthesis were optimized to prepare crystalline, pure phase and template-free small pore zeolite SSZ-16 (AFX) particles. The type of silica source and prolonged ageing process at an elevated temperature were decisive in obtaining pure phase zeolite SSZ-16 particles under static conditions and conventional heating. Colloidal and fumed silica-based synthesis mixtures were successful in forming the zeolite SSZ-16. The zeolite particle size was reduced from 46 to 5 μm when the fumed silica was replaced by colloidal silica. Uniform, fine-grained and fully crystalline zeolite SSZ-16 particles were synthesized only from the colloidal silica-based mixtures that were aged at 80 °C for 7 days. The elevated temperature of the ageing stage is supposed to promote nucleation of viable nuclei leading to the reduction of the induction period. The two cycle calcination procedure with maximal temperature of 550 °C, ensured the removal of template molecules from the bulk phase of zeolite SSZ-16 particles. Carbonaceous residua were observed in zeolite subsurface region and mainly in the core shell morphology of zeolite SSZ-16 particles. The phase purity of zeolite SSZ-16 particles was checked by XRD and sorption properties were determined by N2 adsorption at −196 °C. Zeolite SSZ-16 particles showed the micropore volume of 0.24 cm3/g and BET surface area of 496 m2/g.
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      PubDate: 2016-04-04T13:23:19Z
       
  • Complex investigation of charge storage behavior of microporous carbon
           synthesized by zeolite template
    • Abstract: Publication date: 1 July 2016
      Source:Microporous and Mesoporous Materials, Volume 228
      Author(s): Marija Stojmenović, Milica Vujković, Ljiljana Matović, Jugoslav Krstić, Anđelka Đukić, Vladimir Dodevski, Sanja M. Živković, Slavko Mentus
      Microporous zeolite templated carbon (ZTC) was synthesized by impregnation method using zeolite Y (Na-form) as a template, and furfuryl alcohol as a carbon precursor. The characterization was carried out by X-ray diffractometry, Raman spectroscopy, scanning electron microscopy, nitrogen physisorption, elemental analysis and electrochemical methods. Physisorption measurements evidenced high micropore volume of obtained material (∼0.43 cm3 g−1). The charge storage ability in aqueous KOH, H2SO4 and Na2SO4 solutions was systematically studied by cyclic voltammetry, galvanostatic charging/discharging and complex impedance measurements. Specific coulombic capacitance, the hydrogen storage, HZTC bonding and relaxation time of adsorption were found to be dependent on the type of electrolyte. Neutral Na2SO4 aqueous solution was found to be the best for supercapacitor application, thanks to: i) the highest available voltage window ii) lowest corrosion and iii) highest capacitance amounting to 123 F g−1 at 1 A g−1.
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      PubDate: 2016-04-04T13:23:19Z
       
  • Synthesis and characterization of zeolite L prepared from hydrothermal
           conversion of magadiite
    • Abstract: Publication date: 1 July 2016
      Source:Microporous and Mesoporous Materials, Volume 228
      Author(s): Yu Wang, Tianming Lv, Ye Ma, Fuping Tian, Li Shi, Xiaoyu Liu, Changgong Meng
      Zeolite L has been synthesized by magadiite conversion method. The crystallization behavior and changes of medium-range structure during the crystallization were investigated by X-ray diffraction, scanning electron micrograph, vibrational spectroscopy and 27Al magic angle spinning nuclear magnetic resonance. It is indicated that parts of 6 member-rings in magadiite still exist as secondary building units although the long-range order of magadiite was collapsed in the initial stage. The 4 member-rings and 8 member-rings were formed after the sample was heated for 3 h and 4 h, respectively. The influence of various parameters such as reaction temperature, time and substrate composition was examined. Highly crystallized and pure zeolite L could be prepared from the substrates with molar composition: 0.56M2O–xAl2O3 SiO2 49H2O (M2O = K2O + Na2O, x = 0.0033–0.04) by heating at 140 °C for 18 h, 160 °C for 12 h or 180 °C for 8 h.
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      PubDate: 2016-04-04T13:23:19Z
       
  • Understanding fluid transport through claystones from their 3D nanoscopic
           pore network
    • Abstract: Publication date: 1 July 2016
      Source:Microporous and Mesoporous Materials, Volume 228
      Author(s): Yang Song, C.A. Davy, P. Bertier, D. Troadec
      This paper investigates the complex and nanoscopic pore network of claystones, after their retrieval from the geological layer, and their further conditioning and drying, as it is usually done to assess their fluid permeability (i.e. their transport properties). Following the leading research of Keller et al. [1] on the Swiss Opalinus clay, and because no percolating pore network is obtained at bigger scales, we provide micrometric pore volumes for a French Toarcian claystone and for a Callovo-Oxfordian claystone [2], by Focused Ion Beam/Scanning Electron Microscopy (FIB/SEM) imaging. The voxel size ranges from 5.94 × 7.54 × 10 nm3 to 8.49 × 10.78 × 50 nm3, and the investigated volumes range between 28 and 553 μm3. Comparison with nitrogen adsorption data is proposed. One originality of our research is to prepare the samples as for the assessment of macroscopic fluid transport, by moderate drying at centimetric size. It is observed that, at the scale imaged by FIB/SEM, fluid transport occurs through very limited percolating parts of the pore network (0.7–2.1%). For both claystones, pore volumes generally percolate by sub-micrometric cracks, attributed to drying, and more seldomly by tortuous parts (not of a crack nature). Fluid transport is predicted by Katz–Thompson equation from the 3D geometry of the shortest percolating path. This provides permeability values on the order of 10−21–10−20 m2 (1–10 nD), in good agreement with experimental data. This study hints at a mechanism of fluid transport by fingering through pores as small as 20 nm diameter, rather than homogeneously through the whole claystone volume.
      Graphical abstract image

      PubDate: 2016-04-04T13:23:19Z
       
  • Microwave synthesis of zeolite CHA (chabazite) membranes with high
           pervaporation performance in absence of organic structure directing agents
           
    • Abstract: Publication date: 1 July 2016
      Source:Microporous and Mesoporous Materials, Volume 228
      Author(s): Na Hu, Yuqin Li, Shenglai Zhong, Bin Wang, Fei Zhang, Ting Wu, Zhen Yang, Rongfei Zhou, Xiangshu Chen
      Thin and compact zeolite chabazite membranes were prepared by microwave heating using symmetric stainless steel tubular supports. The microstructures (crystal size and membrane thickness) and separation performances of supported chabazite layers were strongly affected by heating method, synthesis time and synthesis temperature. The best membrane prepared by microwave heating under optimized conditions showed fluxes of 7.3 and 9.1 kg/(m2 h) and separation factors of 2000 and 2500 for 90 wt.% ethanol and isopropanol aqueous solutions at 348 K, respectively. These fluxes were twice as high as those of the chabazite membranes prepared by conventional heating due to the thinner zeolite layers and lower resistance of the support layer in the microwave heating system. The membrane prepared on the 3-time-reused stainless steel support showed comparable separation performance with the membrane on the fresh support, suggesting that the stainless steel supports had a good reuse prospect for chabazite membrane preparation. Synthesis reproducibility and hydrothermal stability of chabazite membranes by microwave heating were also investigated.
      Graphical abstract image

      PubDate: 2016-03-30T13:21:04Z
       
  • Mesoporous In-Sn binary oxides of crystalline framework with extended
           compositional variation
    • Abstract: Publication date: 1 July 2016
      Source:Microporous and Mesoporous Materials, Volume 228
      Author(s): Jangkeun Cho, Changbum Jo, Jae Won Shin, Seung Hyeon Ko, Ryong Ryoo
      Indium-tin oxide is considered a highly promising mixed-metal oxide system, because it shows good performance in various industrial processes. Therefore, it will be of great importance to explore the possibility of obtaining new In-Sn oxides with controlled contents whose properties could be tailored. However, In or Sn content in In-Sn oxides has generally been restricted to <10% because of their low solid solubility into counterpart metal oxide framework. Herein, we report for the first solvothermal synthesis of crystalline mesoporous In-Sn oxides with a broad range of In/Sn ratios and their opto-electrochemical properties. For the synthesis, we use phenolic polymer as a structure-directing agent. Surprisingly, we observe that the phenolic polymer plays a critical role in overcoming their low solubility by manipulating kinetics of crystal nucleation and subsequet growth. As a result, we obtain In-rich rutile SnO2 phase without phase separation with up to 50% In content and Sn-rich rhombohedral In2O3 structure with higher In content. The synthesized materials are highly transparent regardless of In content. The electrochemical properties are sensitive to In content. Our strategy offers possibility of realizing crystalline mesoporous mixed-metal oxides with tunable contents, thus opening a new perspective for the development of optoelectronic materials.
      Graphical abstract image

      PubDate: 2016-03-30T13:21:04Z
       
  • Self-templating synthesis of hollow spheres of zeolite ZSM-5 from
           spray-dried aluminosilicate precursor
    • Abstract: Publication date: 1 July 2016
      Source:Microporous and Mesoporous Materials, Volume 228
      Author(s): Veronika Pashkova, Venceslava Tokarova, Libor Brabec, Jiri Dedecek
      Synthesis of hollow spheres consisting of ZSM-5 zeolite crystals, prepared by a cost- and time-saving self-templating process, requires neither a hard/soft template for sphere formation nor tetraalkylammonium compound as a zeolite structure-directing agent. A preshaped aluminosilicate precursor, obtained by spray drying of a mixture of colloidal solution of silicic acid and aluminum butoxide, plays the role of a shape-directing agent for the formation of spheres, and is used as a source of silica and alumina for zeolite growth. The zeolite structure is directed using ZSM-5 seeds. This method yielded highly stable hollow spheres with diameters of 15–25 μm, consisting of inter-grown ZSM-5 crystals (Si/Al 14) with a size of 0.5–2.0 μm.
      Graphical abstract image

      PubDate: 2016-03-30T13:21:04Z
       
  • Ultrafast microwave synthesis of all-silica DDR zeolite
    • Abstract: Publication date: 1 July 2016
      Source:Microporous and Mesoporous Materials, Volume 228
      Author(s): Lu Bai, Guizhen Nan, Yihui Wang, Deng Hu, Gaofeng Zeng, Yanfeng Zhang, Meng Li, Wei Wei, Yuhan Sun
      Non-seeded ultrafast microwave synthesis of all-silica DDR zeolite was realized using 1-adamantane amine and tetraethylammonium hydroxide. XRD, SEM, NMR, FT-IR, TGA and nitrogen adsorption were used to characterize the obtained samples. The presence of TEAOH suppressed the formation of other phases which allowed the synthesis to be carried out at high temperature. High quality DDR crystals were obtained in only 30 min without seeding, which is the fastest synthesis up to now. 1-Adam serves as template for zeolite DDR and TEAOH is not occluded in zeolite channels. The ultra fast synthesis is the synergy of fast heating from microwave energy, fast kinetics (nucleation and crystallization) at high temperature and phase selectivity from the TEAOH. The obtained DDR crystals have similar properties as those prepared with traditional method.
      Graphical abstract image

      PubDate: 2016-03-30T13:21:04Z
       
  • Ionothermal synthesis of LTA-type aluminophosphate molecular sieve
           membranes with gas separation performance
    • Abstract: Publication date: 1 July 2016
      Source:Microporous and Mesoporous Materials, Volume 228
      Author(s): Xiaolei Li, Keda Li, Shuo Tao, Huaijun Ma, Renshun Xu, Bingchun Wang, Ping Wang, Zhijian Tian
      LTA-type aluminophosphate molecular sieve membranes with gas separation performance were ionothermally synthesized by using δ-alumina substrates as both the supports and the aluminum sources. The effects of the synthesis parameters, such as the concentrations of H3PO4, TAMOH, and HF, and the detailed formation process of the membrane were thoroughly investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX). Furthermore, the subsequent membrane syntheses by using recycled mother liquids were also studied. The results demonstrated that continuous and compact LTA molecular sieve membranes can be prepared over a relatively wide range of the synthesis composition. The membranes prepared with fresh and recycled mother liquids exhibit the same crystallinity, morphology and the gas separation performance. Typically, for single-component gases at 293 K, the ideal separation factors of H2/CO2, H2/O2, H2/N2, and H2/CH4, are 10.9, 8.1, 6.8, and 4.8, respectively, which suggests the good gas separation performance of the membranes.
      Graphical abstract image

      PubDate: 2016-03-30T13:21:04Z
       
  • SBA-15:TiO2 nanocomposites. I. Synthesis with ionic liquids and properties
    • Abstract: Publication date: 1 July 2016
      Source:Microporous and Mesoporous Materials, Volume 228
      Author(s): Alice A.M.L.F. Jardim, Rebeca Bacani, Fernanda F. Camilo, Márcia C.A. Fantini, Tereza S. Martins
      Nanosized titanium dioxide (TiO2) has been extensively studied due to its unique properties and broad applicability. However, to our knowledge, the assessment on how reaction media and synthesis routes affect TiO2 properties synthesized with SBA-15 type mesoporous silica is unprecedented. In this work, SBA-15/TiO2 nanocomposites were prepared in different reaction media, varying ionic liquids (CMITf2N and CMIBF4) with and without isopropyl alcohol. X-ray diffraction results showed that CMIBF4 greatly favors TiO2 anatase crystalline phase, and a single phase material was obtained using 0.032 of CMIBF4 without alcohol. On the other hand, the presence of CMITf2N slightly favored TiO2 rutile crystalline phase. Small Angle X-ray diffraction patterns revealed that ordered mesoporous SBA-15/TiO2 nanocomposites were obtained with lower ionic liquid concentration, whilst materials prepared with higher concentration lost their ordered mesoporous structure. Scanning electron microscopy images showed that materials prepared with ionic liquid and isopropyl alcohol displayed much smaller SBA-15 particle size: around 0.1 μm, instead of the standard 1 μm. Nitrogen adsorption–desorption analysis showed that the nanocomposites exhibited a narrow pore size distribution with high surface areas of up to 680 m2/g, pore volumes of up to 1.8 cm3/g and mean pore diameter of up to 10.4 nm, thus being very promising for application in photocatalysis and photoprotection.
      Graphical abstract image

      PubDate: 2016-03-30T13:21:04Z
       
  • High azobenzene functionalization enhances stability of the cis isomer:
           Periodic mesoporous organosilica network on the way to new light triggered
           applicable materials
    • Abstract: Publication date: 1 July 2016
      Source:Microporous and Mesoporous Materials, Volume 228
      Author(s): Jana Timm, Ulrich Schürmann, Lorenz Kienle, Wolfgang Bensch
      Azobenzene and its derivatives are in the focus of research for the application as molecular switch for medical uses or industrial processes. An optical switchable azobenzene molecule was covalently anchored on the pore walls of a benzene molecule bridged periodic mesoporous organosilica material (abbreviated bz-PMO). The two step synthesis allowed the preparation of a hybrid material with a very high switch density exhibiting an extraordinary long half-life time of 87 h of the cis-isomer. The material was thoroughly characterized applying UV/Vis- and solid state NMR-spectroscopy demonstrating the successful covalent anchoring of the switch onto the pore walls.
      Graphical abstract image

      PubDate: 2016-03-30T13:21:04Z
       
  • Preparation and characterization of novel microporous ultrafiltration PES
           membranes using synthesized hydrophilic polysulfide-amide copolymer as an
           additive in the casting solution
    • Abstract: Publication date: 1 July 2016
      Source:Microporous and Mesoporous Materials, Volume 228
      Author(s): Aazam Jalali, Abbas Shockravi, Vahid Vatanpour, Mohsen Hajibeygi
      Novel asymmetric microporous polyethersulfone (PES)/polysulfide-amide (PSA) blended ultrafiltration membranes with superior properties were prepared using the phase inversion induced by immersion precipitation method. The hydrophilic PSA copolymer with nitro groups, thiazole rings, and thioether linkages was synthesized via phosphorylation polycondensation. Different concentrations of the copolymer were used in the PES casting solutions for improving membrane properties and the results were compared with polyvinyl pyrrolidone (PVP)/PES membrane. The presence of amide band, correlated with the stretching vibration of the carbonyl group and bending vibration of NH group on the ATR-FTIR spectra of the modified membranes confirmed the existence of PSA in the PES membrane structure. The cross-section SEM images showed that the membranes with lower skin layer thickness were formed by addition of PSA in the casting solution. Not only the pure water and BSA solution flux of the blended membranes were increased by enlarging PSA concentrations in the casting solutions up to 2% PSA, but also antifouling properties were improved. Comparing PSA with PVP additive showed that the PSA could improve membrane hydrophilicity, porosity, permeability and antifouling properties. However, the PVP has better performance in case of the porosity and the permeability improvement. Therefore, for coupling of the effect of these two additives, the membrane with 1 wt% PVP and 1 wt% PSA was prepared. The results showed that the prepared membrane had good solution flux with good antifouling properties.
      Graphical abstract image

      PubDate: 2016-03-30T13:21:04Z
       
 
 
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