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PHYSICS (565 journals)            First | 1 2 3 4 5 6 | Last

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NDT & E International     Hybrid Journal   (Followers: 17)
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New Journal of Physics     Open Access   (Followers: 6)
Niels Bohr Collected Works     Full-text available via subscription  

  First | 1 2 3 4 5 6 | Last

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  [2800 journals]
  • Synthesis of cyclophosphazene bridged mesoporous organosilicas for CO2
           capture and Cr (VI) removal
    • Abstract: Publication date: 1 January 2016
      Source:Microporous and Mesoporous Materials, Volume 219
      Author(s): Pawan Rekha, Vivek Sharma, Paritosh Mohanty
      Cyclophosphazene bridged mesoporous organosilicas (CPMOs) were synthesized by condensation of (3-aminopropyl)triethoxysilane (APTES) and phosphonitrilic chloride trimer (PNC) using cetyltrimethylammonium bromide (CTABr) as structure directing and tetraethyl orthosilicate (TEOS) as co-condensing agents under basic condition. Five samples were prepared by varying the molar ratios of APTES:TEOS (1:0, 1:2, 1:3, 1:4 and 1:8). The specific surface area of the CPMOs varies from 34 to 1034 m2 g−1 and pore volume between 0.05 and 0.99 cm3 g−1, depending upon the APTES:TEOS ratios. The CPMO-8 show maximum CO2 uptake of 2.19 mmol g−1 at 273 K. Adsorption potential of the CPMOs for Cr (VI) removal in the aqueous solution was investigated by varying contact time, pH, initial metal ion concentration and temperature. The equilibrium data were analyzed using the Langmuir and Freundlich isotherm by linear regression analysis. In addition, the kinetic analysis revealed that the overall adsorption process was successfully fitted with the pseudo-second-order kinetic model. The maximum Cr (VI) adsorption capacity of 99.24 mg g−1 was observed for the CPMO-4. The thermodynamics studies indicate a spontaneous exothermic process with negative ΔG, and ΔH of −1.808 kJ mol−1. The ΔS was calculated to be 10.718 J mol−1 K−1.
      Graphical abstract image

      PubDate: 2015-08-16T09:47:33Z
       
  • Single-walled carbon nanotubes prepared in small AlPO4-5 and CoAPO-5
           molecular sieves by low-temperature hydrocracking
    • Abstract: Publication date: 1 January 2016
      Source:Microporous and Mesoporous Materials, Volume 219
      Author(s): Wenshen Yang, Weina Sun, Shuheng Zhao, Xiuli Yin
      Single-walled carbon nanotubes (SWNTs) were prepared in the channels of small AlPO4-5 and cobalt-incorporated AlPO4-5 (CoAPO-5) crystals (4–6 μm in diameter and 10–30 μm in length), by hydrocracking at 350 °C. The effects of Co content in the precursor gel and carbon density of the structure-directing agent on the resulting SWNTs were investigated. The results of high-resolution transmission electron microscopy and polarized Raman scattering indicated that SWNTs formed in the channels of AlPO4-5 and CoAPO-5 crystals, after hydrocracking for 10 h at 350 °C. The SWNTs were 0.4 nm in diameter, and possessed well-defined symmetry. When the Co/Al ratio of the precursor gel was 0.075, the relative intensity ratio of Raman D to G band (I D/I G) was 0.286, and the weight loss (500–700 °C) of the SWNTs formed in CoAPO-5 was 3.27 wt%. This Co/Al ratio yielded the lowest obtained I D/I G value and the highest weight loss of SWNTs, which indicated the lowest amorphous carbon density and the highest SWNT quantity. The density and quantity of SWNTs in the AlPO4-5 crystals increased when the structure-directing agent was changed from triethylamine to tripropylamine, because of the higher carbon content of the latter's unit cell. Low-temperature hydrocracking can be used to prepare SWNTs in the channels of AlPO4-5 and CoAPO-5 crystals, even for small low-quality crystals.
      Graphical abstract image

      PubDate: 2015-08-16T09:47:33Z
       
  • Ammoxidation of C2 hydrocarbons over Mo–zeolite catalysts prepared
           by solid-state ion exchange: Nature of molybdenum species
    • Abstract: Publication date: 1 January 2016
      Source:Microporous and Mesoporous Materials, Volume 219
      Author(s): E. Mannei, F. Ayari, M. Mhamdi, M. Almohalla, A. Guerrero Ruiz, G. Delahay, A. Ghorbel
      Successful introduction of molybdenum (from MoCl3) into zeolites of different topologies was carried out using solid-state ion exchange. MOR like support extended the formation of Mo oxides due to its particular aperture/channel-shapes. However, BEA and MFI (ZSM-5) zeolites structures loaded small aggregates of Mo oxide. Exchanging MoCl3 with NH4 +–BEA, H+–ZSM-5 (Si/Al = 15) and NH4 +–ZSM-5 (Si/Al = 26) led to the consumption of Brönsted acid sites and silanol groups, while the lack of exchange sites in NH4 +–MOR generated Mo–OH as revealed by DRIFTS and TPD of NH3. Polymeric Mo and MoO3 occupied the bulk of BEA and MOR issued solids. Nevertheless, NH4 +–ZSM-5 (Si/Al = 26) support triggered the formation of dimeric species. For H+–ZSM-5 (Si/Al = 15) solid, monomeric species migrated throughout the channels of H+–ZSM-5, which condensed easily to form rather polymeric species. Small oxide crystallites and Mo moieties that weakly interact with NH4 +–BEA and NH4 +–ZSM-5 (Si/Al = 26) were easily reduced under hydrogen, while the negatively charged H+–ZSM-5 (Si/Al = 15) framework inhibited the reducibility.
      Graphical abstract image

      PubDate: 2015-08-16T09:47:33Z
       
  • Synthesis and characterization of all-silica DDR zeolite by microwave
           heating
    • Abstract: Publication date: 1 January 2016
      Source:Microporous and Mesoporous Materials, Volume 219
      Author(s): Jianming Zhang, Meng Li, Yanjun Lin, Cheng Liu, Xiangyan Liu, Lu Bai, Deng Hu, Gaofeng Zeng, Yanfeng Zhang, Wei Wei, Yuhan Sun
      All-silica zeolite DDR was prepared by microwave-aided hydrothermal synthesis and characterized by X-ray diffraction, scanning electron microscopy, infra-red spectroscopy, nitrogen adsorption, elemental analysis and thermal gravimetric analysis. Microwave-aided heating significantly reduced the synthesis time from 25 d to 3 d and crystal size from 8 μm to 2 μm. With the help of seeding, the synthesis time and crystal size were further reduced to 6 h and 0.7 μm respectively. The crystal size decreased with seed content. The fragmentation of seed crystals had positive impact on reducing crystal size and increasing product yield. The aging of mother liquor and decrease of H2O/SiO2 had little impact on crystal size.
      Graphical abstract image

      PubDate: 2015-08-16T09:47:33Z
       
  • Durability improvements of H-ZSM-5 zeolite for ethanol conversion after
           treatment with chelating agents
    • Abstract: Publication date: 1 January 2016
      Source:Microporous and Mesoporous Materials, Volume 219
      Author(s): Daniel Däumer, Markus Seifert, Wladimir Reschetilowski
      An H-ZSM-5 zeolite (Si/Al = 12) was treated with solutions of tartaric acid, citric acid and EDTA. The impact of this treatment on the durability in the conversion of ethanol was investigated and correlated with the extraction of small amounts of aluminium. M06-L/6-31G(d) was applied as level of theory for the quantum chemical part of this work. These investigations showed that all EFSPE can be regarded as solvable and hence also as removable. By solid state characterisations (NMR, IR, XRD) no changes in the bulk properties were observed, although catalytic testings of the treated samples showed significant durability improvements. This ostensible contradiction can be explained by a changed ethene supply to the hydrocarbon pool after the removal of EFSPE acting as active sites which catalyse only dehydration reactions.
      Graphical abstract image

      PubDate: 2015-08-16T09:47:33Z
       
  • Preparation of porous carbons based on polyvinylidene fluoride for CO2
           adsorption: A combined experimental and computational study
    • Abstract: Publication date: 1 January 2016
      Source:Microporous and Mesoporous Materials, Volume 219
      Author(s): Seok-Min Hong, Geunsik Lim, Sung Hyun Kim, Jong Hak Kim, Ki Bong Lee, Hyung Chul Ham
      Microporous carbons were developed for CO2 capture from polyvinylidene fluoride (PVDF) via a simple carbonization method. The carbonization was carried out in the temperature range of 400–800 °C, and the effects of the carbonization temperature on the characteristics and CO2 adsorption behavior of the prepared carbon materials were investigated by both experiments and density functional theory studies. The textural characteristics of the carbon materials were highly dependent on the carbonization temperature, and narrow micropores (<0.7 nm) were predominantly generated from the decomposition of PVDF giving off fluorine during carbonization. The specific surface area and pore volume increased up to 1011 m2 g−1 and 0.416 cm3 g−1, respectively, and the highest CO2 adsorption capacity of 3.59 mol kg−1 was obtained at 25 °C and ∼1 bar in PVDF carbonized at 800 °C. The carbonized PVDFs also exhibited highly stable CO2 adsorption uptake and rapid kinetics through repeated adsorption–desorption cycles, showing that carbonized PVDFs are promising adsorbents for CO2 capture. The density functional theory calculation suggested that stable configuration with favorable adsorption energy can be introduced by the removal of fluorine from PVDF, which results in the reduction of repulsive interactions between electronegative fluorine in PVDF and oxygen in CO2 molecule.
      Graphical abstract image

      PubDate: 2015-08-16T09:47:33Z
       
  • Synthesis porous carbon-based solid acid from rice husk for esterification
           of fatty acids
    • Abstract: Publication date: 1 January 2016
      Source:Microporous and Mesoporous Materials, Volume 219
      Author(s): Danlin Zeng, Qi Zhang, Shiyuan Chen, Shenglan Liu, Guanghui Wang
      A porous carbon solid acid was synthesized from biomass rice husk by incompletely carbonization, sodium hydroxide leaching and concentrated H2SO4 sulfonation. The solid acid was characterized by XRD, FT-IR, N2 adsorption-desorption and solid-state NMR spectroscopy. The characterization results reveal that the carbon solid acid shows ultra high surface area of 1233 m2/g and stronger acid strength than that of HZSM-5(Si/Al = 38) zeolite. The catalytic performance was tested by the esterification of oleic acid with methanol. The results indicate that this solid acid catalyst is an excellent catalyst compared with other conventional solid acid.
      Graphical abstract image

      PubDate: 2015-08-16T09:47:33Z
       
  • MOF derived porous carbon supported Cu/Cu2O composite as high performance
           non-noble catalyst
    • Abstract: Publication date: 1 January 2016
      Source:Microporous and Mesoporous Materials, Volume 219
      Author(s): Hongyun Niu, Shuangliu Liu, Yaqi Cai, Fengchang Wu, Xiaoli Zhao
      Porous carbon supported copper composite (Cu/Cu2O/C) was synthesized with a facile, low cost and novel method and used as non-noble-metal catalyst for reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by NaBH4. In the synthetic strategy, metal organic framework Cu3(BTC)2 (also denoted as HKUST-1) was used as both sacrificial template and copper precursor, and phenol formaldehyde resin as carbon precursor. The catalytic Cu/Cu2O nanoparticles (Cu/Cu2O NPs) about 40 nm-in-diameter distributed uniformly both on the internal and external surface of the porous carbon flakes, and took up 33.38–37.56 wt% of the Cu/Cu2O/C composite. Compared with noble metal catalysts, the prepared composite showed comparable high catalytic activity, which was mainly due to their porous structure facilitating diffusion of reactants and products, and the high dispersion of accessible catalytic Cu/Cu2O NPs on porous carbon. Moreover, the synthesized catalyst can be reused for at least five cycles due to its good stability. These results confirmed that the as-prepared Cu/Cu2O/C is promising candidate to replace noble metal for catalytic application.
      Graphical abstract image

      PubDate: 2015-08-16T09:47:33Z
       
  • Synthesis of zeolite Y from diatomite as silica source
    • Abstract: Publication date: 1 January 2016
      Source:Microporous and Mesoporous Materials, Volume 219
      Author(s): Gustavo Garcia, Edgar Cardenas, Saúl Cabrera, Jonas Hedlund, Johanne Mouzon
      Bolivian diatomite was successfully used as a silica source for the synthesis of zeolite Y. Prior to synthesis, the diatomite was leached with sulfuric acid to remove impurities and aluminum sulfate was used as an aluminum source. The raw materials were reacted hydrothermally at 100 °C in water with sodium hydroxide and different Na2O/SiO2 ratios were investigated. The final products were characterized by scanning electron microscopy, X-ray diffraction, gas adsorption and inductively coupled plasma-atomic emission spectroscopy. Diatomites originating from different locations and therefore containing different types and amounts of minerals and clays as impurities were investigated. After optimization of synthesis time, zeolite Y with low SiO2/Al2O3 ratio (3.0–3.9) was obtained at a high yield for high alkalinity conditions (Na2O/SiO2 = 0.85–2.0). Lower Na2O/SiO2 ratios resulted in incomplete dissolution of diatomite and lower yield. Nevertheless, decreasing alkalinity resulted in a steady increase of the SiO2/Al2O3 ratio in zeolite Y. Consequently, it was possible to synthesize almost pure zeolite Y with a SiO2/Al2O3 ratio of 5.3 for a Na2O/SiO2 ratio of 0.6, albeit at a low yield. In this respect, diatomite enables the synthesis of high silica zeolite Y and behaves similarly to colloidal silica in traditional syntheses, with both sources of silica having in common a high degree of polymerization. Interestingly, the presence of minerals and clays in the starting diatomite had marginal effects on the outcome of the synthesis. However, their dissolution resulted in presence of calcium and magnesium in the zeolite Y crystals. Finally, overrun of all investigated compositions resulted in the formation of zeolite P nucleating and growing onto dissolving zeolite Y crystals, which was shown to be triggered when aluminum was completely depleted at high alkalinity.
      Graphical abstract image

      PubDate: 2015-08-11T11:43:46Z
       
  • Synthesis of tungsten carbide on Al-SBA-15 mesoporous materials by
           carburization
    • Abstract: Publication date: 1 January 2016
      Source:Microporous and Mesoporous Materials, Volume 219
      Author(s): M.G. Álvarez, R.J. Chimentão, D. Tichit, J.B.O. Santos, A. Dafinov, L.B. Modesto-López, J. Rosell-Llompart, E.J. Güell, F. Gispert-Guirado, J. Llorca, F. Medina
      Aluminum was incorporated into SBA-15 supports at molar ratios Si/Al = 10 and 2 by the pH-adjusting method. The calcined mesoporous Al-SBA-15 supports, as well as the Al-free SBA-15 support, were impregnated with ammonium paratungstate ((NH4)10·[H2W12O42]·4H2O) aqueous solution. Tungsten carbide (W2C) was synthesized by temperature programmed carburization (TPC) from the WO3 supported on Al-SBA-15 and SBA-15 in a flow of CH4/H2. These resultant materials were characterized by powder X-ray diffraction (XRD), N2 adsorption/desorption, 27Al NMR and Raman spectroscopies, and transmission electron microscopies (TEM and HRTEM). W2C species were obtained after the carburization process in all the materials. The mesoporous structure of the SBA-15 supports was preserved at all synthesis steps. XRD and TEM analyses revealed that the introduction of aluminum species into the SBA-15 greatly enhanced the dispersion of WO3 and W2C phases during the calcination and carburization steps, respectively. In situ XRD measured during the carburization in a synchrotron facility provided further details of the reduction of tungsten trioxide species as a function of temperature. The presence of aluminum in the SBA-15 notably affected the distribution and the reduction temperature of the tungsten oxide species.
      Graphical abstract image

      PubDate: 2015-08-11T11:43:46Z
       
  • Direct synthesis of hierarchical ferrierite nanosheet assemblies via an
           organosilane template approach and determination of their catalytic
           activity
    • Abstract: Publication date: 1 January 2016
      Source:Microporous and Mesoporous Materials, Volume 219
      Author(s): Phatsawit Wuamprakhon, Chularat Wattanakit, Chompunuch Warakulwit, Thittaya Yutthalekha, Wannaruedee Wannapakdee, Somlak Ittisanronnachai, Jumras Limtrakul
      Hierarchical ferrierite (FER) nanosheet assemblies with a ball-shaped morphology were prepared via a direct hydrothermal synthesis by using an organosilane surfactant, 3-(trimethoxysilyl) propyl octadecyl dimethyl ammonium chloride (TPOAC) as structure directing agent (SDA). The prepared nanosheet assemblies not only have a different morphology (micro-spherical nanosheet assemblies) but also a higher hierarchy factor (HF) (0.11) compared with that obtained in the case of conventional FER (plate-like products with HF value of 0.03). The enhanced HF of the FER nanosheet assemblies corresponds to an increase in mesopore surface area as they preserve the microporous zeolitic features in terms of crystallinity and acidity. This results in an improvement of the catalytic activities (82% and 14% conversion efficiency in the cases of the FER nanosheet and the conventional FER, respectively) for the benzylation of toluene with benzyl chloride. We demonstrate a simple way to create hierarchical FER nanosheet assemblies with a 2D pore system by a direct synthesis via an organosilane-SDA approach. This is complementary to the nanosheet design on other types of zeolites besides MFI and FAU nanosheets and opens up the catalytic applications involving bulky molecules like in the case of benzylation.
      Graphical abstract image

      PubDate: 2015-08-11T11:43:46Z
       
  • Fabrication and application of magnetic nanoreactor with multiple
           ultrasmall cores and mesoporous shell in Fenton-like oxidation
    • Abstract: Publication date: 1 January 2016
      Source:Microporous and Mesoporous Materials, Volume 219
      Author(s): Wenjing Cheng, Yanqiu Jiang, Xiaowei Li, Yudong Li, Xianzhu Xu, Kaifeng Lin, Yan Wang
      A new and facile method has been developed in this study for the fabrication of multicore–shell type nanoreactor. On the basis of the characterization results from X-ray diffraction, scanning and transmission electron microscopy, Raman and X-ray photoelectron spectroscopy, and N2 adsorption/desorption analysis, it has been proved that ultrasmall iron oxide particles (∼10 nm) were firstly encapsulated in the matrix of polystyrene spheres via a microemulsion-polymerization-assisted approach, and then were introduced as movable cores inside mesoporous SiO2 shell. The size of iron oxide particles retained almost unchanged even during the calcination procedure in air, indicating high thermal stability, due to the protection of polystyrene matrix. The obtained nanoreactor was applied as an effective heterogeneous catalyst for total oxidation of methylene blue with aqueous hydrogen peroxide and the ultrasmall iron oxide particles within the hollow interior proved to be active sites for such reaction. Mesoporous SiO2 shell not only protects the nanometer-sized iron oxide particles against leaching from the nanoreactor into reaction solution, but also enriches the reactant molecules around multiple ultrasmall iron oxide cores and thus enhances the catalytic activity and reaction rate. Importantly, the nanoreactor can be easily recovered by external magnetic field and reused in successive catalytic cycles without significant loss of activity.
      Graphical abstract image

      PubDate: 2015-08-11T11:43:46Z
       
  • Enhancement of the graphitic carbon nitride surface properties from
           calcium salts as templates
    • Abstract: Publication date: 1 January 2016
      Source:Microporous and Mesoporous Materials, Volume 219
      Author(s): Pierre Gibot, Fabien Schnell, Denis Spitzer
      A graphitic carbon nitride material with enhanced surface properties has been successfully synthesized from guanidine monohydrochloride used as carbon nitride precursor, and from calcium salts nanoparticles used as templates. The products were characterized by X-ray Diffraction (XRD), chemical analysis, Fourier Transform Infra-Red spectroscopy (FTIR), nitrogen adsorption, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Ultra-Violet Visible spectroscopy (UV–Vis). The results show that the products adopt a graphitic structure with basal planes made of carbon and nitrogen atom species linked together by single and double bonds in an aromatic array (s-triazine, tri-s-triazine ring). As a function of the amount of the calcium-based template, a series of mesoporous materials was prepared which had specific surface areas ranging from 24.0 to 39.4 m2/g and coupled with pore volumes of 0.13–0.22 cm3/g. Instead of using the usual silica hard templates, our results show that using CaCO3 and Ca3(PO4)2 nanoparticles appears to be an encouraging solution for developing the surface properties of the carbon nitride. The carbon nitride is a promising candidate in the field of photocatalysis.
      Graphical abstract image

      PubDate: 2015-08-11T11:43:46Z
       
  • An EPR study of clinoptilolite from Bigadiç in Turkey
    • Abstract: Publication date: 1 January 2016
      Source:Microporous and Mesoporous Materials, Volume 219
      Author(s): Recep Bıyık, Recep Tapramaz
      Natural and synthetic zeolites have wide use industry and in many other applications as food additives, as molecular sieve to trap unwanted ingredients like heavy metallic ions and groups in fluids, as shielding materials against high energy radiations etc. Clinoptilolite is a type of zeolite composed of aluminasilicate forming tetrahedrons with micro cavities among them. The size and shape of cavities, impurities and the metal ions define their usage. Electron paramagnetic resonance (EPR) spectroscopy is a technique to determine paramagnetic species in host materials, and hence in the zeolites and clay type minerals. In this study natural clinoptilolite obtained from Bigadiç district in Western Anatolia, was studied using EPR spectroscopy in natural form and after some physical and chemical treatments, namely adsorbing CO2, H2S, and SO2 gases, [Cu(H2O)6]2+ ions and after exposing to gamma rays. The clinoptilolite including non-paramagnetic manganese ions as impurities in natural form reduced to paramagnetic Mn2+ ions after CO2 and H2S adsorption, and when SO2 gas is adsorbed an unstable paramagnetic center was induced which changed with time when stored at room temperature. When Cu(H2O)6 was adsorbed Cu2+ ion complex was adsorbed in the cavity in slightly distorted octahedral structure. Gamma ray irradiation of clinoptilolite from Co-60 source produced anisotropic o 2 3 − radical ion.
      Graphical abstract image

      PubDate: 2015-08-11T11:43:46Z
       
  • Physicochemical properties and mechanism study of clinoptilolite modified
           by NaOH
    • Abstract: Publication date: 1 December 2015
      Source:Microporous and Mesoporous Materials, Volume 218
      Author(s): Hai Lin, Quan-li Liu, Ying-bo Dong, Yin-hai He, Liang Wang
      The change of surface area and pore volume distributions, cation exchange capacity, ammonia nitrogen removal ability of clinoptilolite modified by NaOH was investigated. The mechanism of modification was characterized through XRD, FTIR, NMR and XPS. The results indicated that alkalis modification would increase the proportion of mesoporous and the cation exchange capacity of the clinoptilolite. When the concentration of NaOH was 1.50 mol/L, the proportion of mesoporous and the cation exchange capacity were increased from 63.82%, 169.67 mmol·(100 g)−1 to 74.51%, 186.25 mmol·(100 g)−1, while the removal rate of ammonia nitrogen in water increased to 79.66% from original 53.45%. It found that ammonia nitrogen removal ability was positively correlated with the cation exchange capacity. The ICP-OES results showed that the solution emerged K+, Al3+ and Si4+ after modified, but the XRD, FTIR, NMR and XPS solid results showed that the crystal structure, molecular groups, the binding energy of atoms, and Si, Al ligand state of the clinoptilolite had not changed. Therefore, it was considered that the modification mechanism of NaOH was mainly through removal of the silicon which combined weaker with the clinoptilolite framework, thus dissolving out channel impurities and increasing the proportion of mesoporous, meanwhile enhanced the removal ability of ammonia nitrogen in water by the addition of Na+.
      Graphical abstract image

      PubDate: 2015-08-07T11:40:50Z
       
  • Mesopore modification of beta zeolites by sequential alkali and acid
           treatments: Narrowing mesopore size distribution featuring unimodality and
           mesoporous texture properties estimated upon a mesoporous volumetric model
           
    • Abstract: Publication date: 1 December 2015
      Source:Microporous and Mesoporous Materials, Volume 218
      Author(s): Yingjie Jin, Changchun Xiao, Jinhuan Liu, Shudong Zhang, Sachio Asaoka, Shanlin Zhao
      For mesopore modification of zeolite beta prepared in protonic form (H-Beta, Si/Al = ca.18.7) to concentrate pore size distributions, the framework T-atoms of H-Beta crystals were extracted according to the sequential schemes: hydrothermal pre-etching using incipiently wetted alkaline solutions, bulk alkaline treatment, and acid leaching coupling with ammonium exchange. Based on XRD, FTIR, N2 adsorption at 77 K, SEM, TEM, EDX, ICP–AES, and immersion porosimetry, structure properties of the hierarchical materials obtained were correlated with the sequential treatment processes. In contrast to single bulk alkaline treatment, the hydrothermal alkali pre-etching enables to impair or eliminate broadly secondary pore–distributed peaks, the bulk alkaline treatment before acid leaching facilitates textural mesopore formation, and the final acid leaching plus ammonium exchange leads to moderate increases in mesoporosity and mesopore diameters, and also to a suitable enhancement of Si/Al ratios. FTIR spectra provided evidence for the short range ordering of modified zeolites and for the presence of zeolitic ring sub-units in the basic filtrate. However, the microporosity, crystallinity and yield relative to the parent are reduced by increased alkaline concentrations. A novel model was built for estimating a volumetric fraction of intracrystalline-to N2 adsorbed mesopores. Calculation results show that this volumetric fractional model promises to identify the mesoporous textural property, explaining how many volumetric fractions of mesopores are to locate in beta crystallite entities. In addition, the hierarchical beta possesses a mesopore network with higher hydrothermal stability at 873 K.
      Graphical abstract image

      PubDate: 2015-08-07T11:40:50Z
       
  • Fast and one-pot synthesis of silica aerogels via a
           quasi-solvent-exchange-free ambient pressure drying process
    • Abstract: Publication date: 1 December 2015
      Source:Microporous and Mesoporous Materials, Volume 218
      Author(s): Jin Wang, Yulu Zhang, Yong Wei, Xuetong Zhang
      A very fast (less than 2 h) and one-pot synthetic strategy was developed for the synthesis of silica aerogels. Organic silica gel was first formed under basic condition by adding a predetermined amount of hexane to a freshly prepared silica sol. After aging at elevated temperature for several minutes, the organogel was mechanically crushed and vigorously stirred in a mixture of trimethylchlorosilane and hexane. Finally, silica aerogel was produced by drying the hydrophobized organogel at temperatures higher than 180 °C. The effects of gelation conditions, amount of modification agents, and drying temperatures on the physical properties of the silica aerogels were investigated. The N2 adsorption and desorption measurements indicated that high BET surface areas (up to 725.8 m2/g) could be obtained for the aerogels sintering at 350 °C, while that of the silica aerogels dried at 180 °C were relative lower (from 379.4 to 564.8 m2/g based on the modification conditions). Similar trend was also found in the thermal conductivities of the aerogels, e.g., lower values of thermal conductivity (∼0.025 W/mK) were obtained for the sintering samples, while that of the samples without sintering were relative higher (∼0.034 W/mK). In summary, a fast ambient pressure drying method has been developed, which show a great potential to synthesize silica aerogels in the industrial scale.
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      PubDate: 2015-08-07T11:40:50Z
       
  • Novel synthesis of a micro-mesoporous nitrogen-doped nanostructured carbon
           from polyaniline
    • Abstract: Publication date: 1 December 2015
      Source:Microporous and Mesoporous Materials, Volume 218
      Author(s): A. Silvestre-Albero, J. Silvestre-Albero, M. Martinez-Escandell, M. Molina-Sabio, A. Kovacs, F. Rodriguez-Reinoso
      Nanostructured carbons with relatively high nitrogen content (3–8%) and different micro and mesoporosity ratio were prepared by activation of polyaniline (PANI) with a ZnCl2–NaCl mixture in the proportion of the eutectic (melting point 270 °C). It was found that the activated carbons consisted of agglomerated nanoparticles. ZnCl2 plays a key role in the development of microporosity and promotes the binding between PANI nanoparticles during heat treatment, whereas NaCl acts as a template for the development of mesoporosity of larger size. Carbons with high micropore and mesopore volumes, above 0.6 and 0.8 cm3/g, respectively, have been obtained. Furthermore, these materials have been tested for CO2 capture and storage at pressures up to 4 MPa. The results indicate that the nitrogen groups present in the surface do not seem to affect to the amount of CO2 adsorbed, not detecting strong interactions between CO2 molecules and nitrogen functional groups of the carbon, which are mainly pyridinic and pyrrolic groups.
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      PubDate: 2015-08-07T11:40:50Z
       
  • Editorial Board
    • Abstract: Publication date: 15 November 2015
      Source:Microporous and Mesoporous Materials, Volume 217




      PubDate: 2015-08-07T11:40:50Z
       
  • Methane adsorption on specially designed TiC and Mo2C derived carbons with
           different pore size and surface morphology
    • Abstract: Publication date: 1 December 2015
      Source:Microporous and Mesoporous Materials, Volume 218
      Author(s): Rasmus Palm, Indrek Tallo, Tavo Romann, Heisi Kurig
      The effect of pore size and surface morphology of carbon materials on the adsorption of methane was studied selecting three microstructurally different carbide-derived carbons (CDC), synthesized from titanium carbide (TiC-CDC 950 °C and TiC-CDC 1100 °C HCl) and molybdenum carbide (Mo2C-CDC 1000 °C). Nitrogen sorption and Raman spectroscopy methods were used to obtain the specific surface area, ratio of micro- and mesopores, the pore size distribution and disorder in structure, respectively. Studied CDCs had high surface area (>800 m2 g−1), but the pore size distribution was remarkably different. TiC-CDC 950 °C contains mainly micropores (from 0.5 to 1 nm), TiC-CDC 1100 °C HCl both micro- and mesopores (from 1.5 to 5 nm) and Mo2C-CDC 1000 °C mainly mesopores (from 2.5 to 10 nm). Structural correlation lengths calculated from Raman spectra showed that CDC with the smallest pores (TiC-CDC 950 °C) was the most disordered of carbon materials studied. Excess isotherms (EI) of methane adsorption were measured at different temperatures (from −100 to 40 °C) and pressures (from 0.03 to 1.35 MPa) and modelled with modified Langmuir equation to obtain the absolute adsorption isotherms, enthalpies and entropies of methane adsorption. It was concluded that the change in entropy is the key factor determining the amount of gas adsorbed per unit of surface area of CDC and up to 55% more methane can be adsorbed if the structure of carbon material is optimized.
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      PubDate: 2015-08-03T03:21:45Z
       
  • Host–guest-recognition-based polymer brush-functionalized mesoporous
           silica nanoparticles loaded with conjugated polymers: A facile FRET-based
           ratiometric probe for Hg2+
    • Abstract: Publication date: 1 December 2015
      Source:Microporous and Mesoporous Materials, Volume 218
      Author(s): Jie Sha, Yajiao Song, Bingxin Liu, Changli Lü
      This article reports a new strategy for constructing a fluorescence resonance energy transfer (FRET) based ratiometric sensor for Hg2+ detection with organic-inorganic hybrid mesoporous silica nanoparticles (MSNs) as the scaffolds. The fluorescent conjugated polymer of poly(p-phenylenevinylene) (PPV) as the donor is encapsulated into the MSNs and a spirolactam rhodamine-linked adamantane (AD-SRhB) as mercury ion-recognition element is introduced to cyclodextrin (CD) functionalized polymer brush on the shell of MSNs via the host–guest interaction. Upon the addition of Hg2+, the rhodamine spirocyclic ring opens, and the fluorescence (578 nm) of rhodamine is observed due to the FRET. This novel nanosensor can selectively detect Hg2+ ions with a detection limit of 4.2 μM. On the other hand, compared with pure AD-SRhB as probe, the novel ion probe fabricated by us can selectively detect Hg2+ from other correlative metal ions, especially Fe3+ and Al3+.
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      PubDate: 2015-08-03T03:21:45Z
       
  • Structural stability and Lewis acidity of tetravalent Ti, Sn, or Zr-linked
           interlayer-expanded zeolite COE-4: A DFT study
    • Abstract: Publication date: 1 December 2015
      Source:Microporous and Mesoporous Materials, Volume 218
      Author(s): Haichao Li, Juan Wang, Danhong Zhou, Dongxu Tian, Chuan Shi, Ulrich Müller, Mathias Feyen, Hermann Gies, Feng-Shou Xiao, Dirk De Vos, Toshiyuki Yokoi, Xinhe Bao, Weiping Zhang
      Density functional theory (DFT) has been performed to characterize the structural stability and Lewis acidic properties of the T-COE-4 zeolites, in which the linked site between the layers is isomorphously substituted by the tetravalent Ti-, Sn-, or Zr- heteroatom. The effects of substitution energy and equilibrium geometry parameters on the stability of T-COE-4 are investigated. The computed Fukui function values and the adsorption of ammonia, pyridine, water and trimethylphosphine oxide molecules have been employed to predict the Lewis acid strength of the T-COE-4 zeolites. It is found that the smaller the O1-T-O2 bond angle is, the more difficult is to form the regular tetrahedral unit. The substitution energies at the linker position increase in the following sequence: Ti-COE-4 < Sn-COE-4 < Zr-COE-4. The incorporation of Ti-, Sn-, or Zr-heteroatom enhances the Lewis acidity of COE-4 zeolite. It is predicted that the Lewis acid strength increases in the order of Ti-COE-4 < Zr-COE-4 ≤ Sn-COE-4 by the adsorption of different base molecules. Six O-T-O bond angles are divided into different extent to form the analogous trigonal bipyramid structures in the optimized ligand adsorbed complexes. These findings could be beneficial for the structural design and catalytic function modification of the interlayer-expanded zeolites.
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      PubDate: 2015-08-03T03:21:45Z
       
  • Removal of the CO2 from flue gas utilizing hybrid composite adsorbent
           MIL-53(Al)/GNP metal-organic framework
    • Abstract: Publication date: 1 December 2015
      Source:Microporous and Mesoporous Materials, Volume 218
      Author(s): Sina Pourebrahimi, Mohammad Kazemeini, Ensieh Ganji Babakhani, Armin Taheri
      In this study, adsorption of the CO2 and N2 gases on the MIL-53(Al) and its hybrid composite with the graphene nano-plates (GNP), MIL-53(Al)/GNP, adsorbents were investigated. These materials were synthesized using the solvothermal reaction method. The prepared samples were characterized by means of the powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FESEM), N2 adsorption–desorption isotherms (BET-BJH surface area measurement) and Fourier transfer infrared (FT-IR) spectroscopy methods as well as; thermogravimetric analysis (TGA). Adsorption equilibrium of the CO2 and N2 on the sorbents were determined through a volumetric adsorption apparatus at 298, 323 and 348 K and pressures of up to 40 bars. It was found that, the adsorption capacities of the CO2 on the MIL-53(Al)/GNP containing 5 wt% GNP increased about 35% (from 9.61 to 12.95 mmol gr−1) in comparison with that of the GNP free sample at 298 K and 40 bars. This enhancement in the adsorption capacity was attributed to the incorporation effect of the GNP displayed in terms of the increase of the specific surface area (SBET), internal pore volume (Vp) and micropore volume (Vmicro) of the MIL-53(Al). Finally, several dual sites isotherm models including the; Langmuir, Sips and Toth were utilized to fit the obtained adsorption experimental data trying to describe the observed breathing effect. In this venue, the ΔH ads was calculated in order to predict the thermodynamic behaviors of this MIL sorbent due to adsorption of the CO2.
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      PubDate: 2015-08-03T03:21:45Z
       
  • Effect of ball milling on the structural and textural features of MCM-41
           mesoporous material
    • Abstract: Publication date: 1 December 2015
      Source:Microporous and Mesoporous Materials, Volume 218
      Author(s): Bahaa M. Abu-Zied, Wilhelm Schwieger, Abdullah M. Asiri
      This paper reports on the ball-milling process and its influence on the structural, textural and morphological features of mesoporous MCM-41 material. MCM-41 and the as-milled products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), N2-adsorption, a field emission scanning electron microscope (FE-SEM) and a thermogravimetric analysis (TGA). The XRD showed that the mechanical treatment of MCM-41 in a ball mill leads to a gradual crystallinity loss with time until 2 h, and complete crystallinity loss was observed after 4 h of ball milling. N2 sorption measurements revealed a sharp surface area decrease as well as mesoporosity loss accompanying the milling process. The FE-SEM investigation demonstrated severe damage of the spherical morphology of MCM-41 upon milling for 8 h. Moreover, it was found that these structural, textural and morphological changes strongly affected the water content of the milled MCM-41 material.
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      PubDate: 2015-08-03T03:21:45Z
       
  • Molecularly imprinted polymer with a pseudo-template for thermo-responsive
           adsorption/desorption based on hydrogen bonding
    • Abstract: Publication date: 1 December 2015
      Source:Microporous and Mesoporous Materials, Volume 218
      Author(s): Takuya Kubo, Katsuaki Koterasawa, Toyohiro Naito, Koji Otsuka
      We report a thermo-responsive molecularly imprinted polymer (MIP) for methotrexate, an anticancer drug. The bulk MIPs were prepared with divinylbenzene as a crosslinker, a variety of functional monomers, and folic acid as a pseudo-template molecule. As a result of simple batch adsorption for methotrexate or folic acid using the MIPs, the selectivity depended on the functional monomers because the functional groups of methotrexate or folic acid were slightly different in each other. After optimization of the preparation conditions, only acidic functional monomers including methacrylic acid (MAA) and sodium p-styrenesulfonate (SS) contributed to the selective adsorption for methotrexate. Furthermore, only the MAA-based MIP provided the thermal responsibility for the binding/release of methotrexate by the suppression of hydrogen bonding at higher temperature, whereas a strong ionic interaction was contributed among broad temperature range in the SS-based MIP. Adsorption isotherms also well supported the differences of the molecular recognition based on the binding constants at low and higher temperatures. Finally, we successfully demonstrated the drug-releasing ability by simple temperature changing with the MAA-based MIP.
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      PubDate: 2015-07-29T20:50:45Z
       
  • Modification of mesoporous silica magnetite nanoparticles by
           3-aminopropyltriethoxysilane for the removal of Cr(VI) from aqueous
           solution
    • Abstract: Publication date: 1 December 2015
      Source:Microporous and Mesoporous Materials, Volume 218
      Author(s): Samira Hozhabr Araghi, Mohammad H. Entezari, Mahmoud Chamsaz
      Silica magnetite nanoparticles (S-MNPs) as core were embedded in mesoporous silica shells by using cetyltrimethylammonium bromide (CTAB) as a surfactant. Then, the resultant mesoporous silica-magnetite nanoparticles (M-S-MNPs) were modified with 3-aminopropyltriethoxysilane (APTES) as a coupling agent in dry hexane solvent. APTES-grafted mesoporous silica magnetite nanoparticles (A-M-S-MNPs) were characterized by XRD, FTIR spectroscopy, EDX, TEM, elemental analysis, TGA/DTA technique. Results demonstrate that the obtained A-M-S-MNPs were nearly spherical in shape with 25 nm thick mesoporous silica shell. The adsorption behavior of the nanocomposite was examined in removing of Cr(VI) ion with concentrations 20, 30 and 50 mg/L at optimum pH level of 2. In this study a pH swing adsorption was observed too. The adsorption kinetic data were modeled using pseudo-second-order kinetics and intraparticle diffusion equations. The obtained results for intraparticle diffusion model show that the adsorption mechanisms are different in low and in high concentrations of Cr(VI) ion. According to the parameters of the Langmuir isotherm, the maximum adsorption capacity (qm) of A-M-S-MNPs for Cr(VI) increases as the temperature rises from 298 to 318 K. For better understanding of adsorption mechanism, quantum mechanical methods were applied. The results indicate that the electrostatic and hydrogen bond interactions between surface functional groups and HCrO 4 − ions have an important role in adsorption process. The easy separation from aqueous solution by an external magnetic field, rapid adsorption, regeneration, and reusability of A-M-S-MNPs are interesting points as an effective adsorbent for the removal of Cr(VI) ions.
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      PubDate: 2015-07-29T20:50:45Z
       
  • PEG-templated mesoporous silicas using silicate precursor and their
           applications in desiccant dehumidification cooling systems
    • Abstract: Publication date: 1 December 2015
      Source:Microporous and Mesoporous Materials, Volume 218
      Author(s): Heru Setyawan, Minta Yuwana, Ratna Balgis
      Polyethylene glycol (PEG) was employed as a templating agent for the preparation of mesoporous silica materials starting from sodium silicate solutions using a sol–gel method. We show that PEG can serve as a structure-directing agent resulting in silica structures with pores spanning a range of 3.3–3.9 nm depending on the PEG concentration and the PEG removal method. The use of a PEG template increased significantly the surface area from 252 m2 g−1 without PEG to >340 m2 g−1 and >634 m2 g−1 when the PEG was removed by, respectively, calcination and solvothermal extraction. It appears that calcination at high temperature caused a densification of the pore structure resulting in a smaller surface area and pore diameter. The impregnation of mesoporous silica with CaCl2 significantly increased the adsorption capacity of water. At high humidity, the composite adsorbents containing approximately 42 wt.% CaCl2 yield a maximum adsorption capacity of 1.6 times their own weight and 4.4 times that of bare silica. The adsorption is physical in nature as viewed from the adsorption energy calculated by the Dubinin–Radushkevich (D–R) equation.
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      PubDate: 2015-07-29T20:50:45Z
       
  • Synthesis of carbon core–shell pore structures and their performance
           as supercapacitors
    • Abstract: Publication date: 1 December 2015
      Source:Microporous and Mesoporous Materials, Volume 218
      Author(s): Teguh Ariyanto, Boris Dyatkin, Gui-Rong Zhang, Andreas Kern, Yury Gogotsi, Bastian J.M. Etzold
      High-power supercapacitors require excellent electrolyte mobility within the pore network and high electrical conductivity for maximum capacitance and efficiency. Achieving high power typically requires sacrificing energy densities, as the latter demands a high specific surface area and narrow porosity that impedes ion transport. We present a novel solution for this optimization problem: a nanostructured core–shell carbonaceous material that exhibits a microporous carbon core surrounded by a mesoporous, graphitic shell. Our tunable synthesis parameters yielded a structure that features either a sharp or a gradual transition between the core and shell sections. Electrochemical supercapacitor testing using organic electrolyte revealed that these novel core–shell materials outperform carbons with homogeneous pore structures. The hybrid core–shell materials showed a combination of good capacitance retention, typical for the carbon present in the shell and high specific capacitance, typical for the core material. These materials achieved power densities in excess of 40 kW kg−1 at energy densities reaching 27 Wh kg−1.
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      PubDate: 2015-07-29T20:50:45Z
       
  • Intercalation of poly(3,4-ethylenedioxythiophene) within halloysite
           nanotubes: Synthesis of composites with improved thermal and electrical
           properties
    • Abstract: Publication date: 1 December 2015
      Source:Microporous and Mesoporous Materials, Volume 218
      Author(s): Alberto Rosas-Aburto, Ismael A. Gabaldón-Saucedo, Francisco Espinosa-Magaña, M.T. Ochoa-Lara, Pedro Roquero-Tejeda, Martín Hernández-Luna, Javier Revilla-Vázquez
      Improvements in thermal stability and electrical conductivity of poly(3,4ethylenedioxythiophene), or PEDOT, were observed by bonding it to an acidified nano-structured tubular silico-aluminate clay, Halloysite (HNT), obtaining the corresponding doped composite (PEDOT:HNT). The composites were synthesized via suspension polymerization in aqueous media using ammonium persulfate (APS) as oxidant. Changes in the hydrodynamic conditions and APS/EDOT ratio were studied. PEDOT was also doped with hydrochloric acid and poly(p-styrene sulfonic acid). PEDOT:HNT composites were characterized by Scanning Transmission Electron Microscopy with Energy-Dispersive X-ray spectroscopy (STEM-EDS), Thermogravimetric analysis (TGA), X-Ray Diffraction (XRD), Four Point Electrical Conductivity Tests and Nitrogen Adsorption Analysis in order to obtain the surface area and the pore size distribution (PSD) of bare and coated halloysite. We observed that the halloysite, which is made of multilayer nano-tubes, does not appear to work only as a template. Halloysite nanotubes interact with PEDOT as functional dopants, resulting in PEDOT:HNT composites with high thermal stability and electrical conductivity. XRD analysis revealed intercalation of PEDOT inside the halloysite nano-tubes. XRD analysis also showed that the polymer/nano-clay interaction does not merely take place at the surface or inside the lumen, but does also modify the properties at the HNT walls, restricting PEDOT mobility. STEM-EDS of a transverse observation of a single PEDOT:HNT nano-tube confirmed that carbon and sulfur (associated to PEDOT) are found inside the halloysite walls. Moreover, STEM, XRD, measured PSD and TGA tests demonstrate a strong influence of hydrodynamic synthesis variables on the amount of free and intercalated PEDOT in HNT walls and, as a consequence, on its electrical conductivity.
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      PubDate: 2015-07-29T20:50:45Z
       
  • Stress control of porous silicon films for microelectromechanical systems
    • Abstract: Publication date: 1 December 2015
      Source:Microporous and Mesoporous Materials, Volume 218
      Author(s): Xiao Sun, Adrian Keating, Giacinta Parish
      Control of stress in porous silicon (PS) through porosity changes was studied using X-ray diffraction rocking curve measurements. The effect of thermal annealing on the stress was also investigated with both X-ray diffraction and radius of curvature measurements. Annealed films could achieve compressive or tensile stress. The effect of annealing was reversed by a short HF dip, except in the case of nitridised samples (annealed in N2 at temperatures above 500 °C). The effect of hydrogen desorption, oxidation and nitridation, modified via annealing temperature and ambient, was studied to understand the evolution of physical properties and the mechanism of the stress modification. The effect of stress on PS microbeams was studied to determine the influence when PS films are used as the structural layer in a micromachined device. When modelling the effect of stress changes on the order of those observed during thermal annealing, the results indicated that for PS-based microbeams, stress is a significant factor in determining resonant frequency, far more than found in nonporous materials, illustrating the need for accurate control of stress.
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      PubDate: 2015-07-29T20:50:45Z
       
  • The effect of surface modification of zeolite 4A on the physical and
           electrical properties of copolyimide hybrid films
    • Abstract: Publication date: 1 December 2015
      Source:Microporous and Mesoporous Materials, Volume 218
      Author(s): Merve Biçen, Nilhan Kayaman-Apohan, Sevim Karataş, Fatih Dumludağ, Atilla Güngör
      In the present work a series of copolyimide (PI) hybrid films that contained zeolite 4A were prepared and the effect of surface modification of zeolite on physical and electrical properties of hybrid films was investigated. (3-aminopropyl)trimethoxysilane was used to modify the zeolite surface. DC conductivity measurements were performed at room temperature and the capacitance was measured in the temperature range of 295–458 K in a vacuum ambient in the dark. The surface modification of zeolite contributed to thermal, mechanical and hydrophobicity properties of PI hybrid films. Morphological investigation also indicated that the interface between polyimide and zeolite phases improved when modified zeolite was used. Dielectric measurements revealed that dielectric constant of the films increased with increasing temperature and decreased with increasing frequency. Variation in dielectric constants of zeolite-doped and modified zeolite-doped films showed opposite behaviors with zeolite loading, due to different interaction types between polymer and zeolite.
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      PubDate: 2015-07-25T21:31:32Z
       
  • Low temperature, rapid solution growth of antifouling silver-zeolite
           nanocomposite clusters
    • Abstract: Publication date: 1 December 2015
      Source:Microporous and Mesoporous Materials, Volume 218
      Author(s): Maxine Swee-Li Yee, Poi Sim Khiew, Yuen Fen Tan, Wee Siong Chiu, Yih-Yih Kok, Chee-Onn Leong
      Biofouling is a common and pervasive problem which reduces the efficiency of man-made marine structures. Silver-zeolite (AgZ) nanocomposite material is proposed as a promising anti-microfouling agent. Metallic silver nanoparticles were immobilized on silver ion doped ZSM-5 zeolites using a green reducing agent, trisodium citrate. The stable and porous inner structure of ZSM-5 zeolites performs a dual role as a stable size-control template and a reservoir of antimicrobial nanosilver. SEM revealed the globular and cluster-like morphology of the AgZ composites, with a homogenous distribution of silver particles on the surface of the AgZ clusters, while TEM analysis indicated Ag nanoparticles could be detected both on the surface and within the zeolite. UV–visible analysis on AgZ displayed the characteristic surface plasmon resonance absorption maximum for Ag nanoparticles ranging from 408 to 500 nm. Indeed, BET analysis also showed a reduction in surface area of up to 44% with the incorporation of Ag nanoparticles into the zeolite, indicating the formation and growth of Ag within ZSM-5 zeolite. XRD analysis indicated the presence of metallic Ag while the ZSM-5 crystalline framework remained largely intact after the Ag crystal growth process. The AgZ nanocomposites were evaluated for their biofilm inhibition activity against Halomonas pacifica, a common marine bacterium implicated in the early stages of biofouling. AgZ loaded with up to 10 wt% Ag reduced biofilm attachment by 81%, and inhibited the growth of marine microalgae Dunaliella tertiolecta and Isochrysis sp. Overall, results demonstrated the effective anti-microfouling property of AgZ nanocomposites.
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      PubDate: 2015-07-25T21:31:32Z
       
  • A new strategy based on thermodiffusion of ceramic nanopigments into metal
           surfaces and formation of anti-corrosion coatings
    • Abstract: Publication date: 1 December 2015
      Source:Microporous and Mesoporous Materials, Volume 218
      Author(s): Maryam Shaterian, Asma Khoobi, Morteza Enhessari, Keyvan Ozaee
      The present paper is the first report about preparation of anti-corrosion coatings based on thermodiffusion of ceramic nanopigments into metal surfaces. At first, Cr1.3Fe0.7O3 ceramic nanopigments have been synthesized by simple and environmentally benign sol–gel method. Annealing of the gels at different temperatures ranging from 600 to 1000 °C yielded the pure rhombohedral structure. The structural evolutions and microstructural characteristics of the synthesized nanoceramics were investigated through different methods containing X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Then Cr1.3Fe0.7O3 ceramic nanopigments were coated on mild steel surface via thermodiffusion method. The surface morphology and the corrosion behavior of the Cr1.3Fe0.7O3 coatings were evaluated using atomic force microscopy (AFM), field-emission scanning electron microscopy (FE-SEM), electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and weight loss measurements in a solution of 2.0 M HCl. It is found that morphology of diffusion coatings affects the protective properties of mild steel. On the other hand, in extra-corrosive HCl media Cr1.3Fe0.7O3 nanoceramic coatings provide mild steel with high protective properties.
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      PubDate: 2015-07-25T21:31:32Z
       
  • Enhanced ammonia adsorption on functionalized nanoporous carbons
    • Abstract: Publication date: 1 December 2015
      Source:Microporous and Mesoporous Materials, Volume 218
      Author(s): Ali Qajar, Maryam Peer, Mohammad Reza Andalibi, Ramakrishnan Rajagopalan, Henry C. Foley
      Nanoporous carbons were synthesized and treated with nitric acid after which the change in their propensities for ammonia adsorption was determined. The adsorbents had mean pore sizes ranging from 0.5 to 12 nm and they included polyfurfuryl alcohol (PFA)-derived carbons, commercial activated carbons, and both soft and hard-templated mesoporous carbons. The carbons were treated with concentrated nitric acid at elevated temperatures (e.g. 90 °C) and for time spans between 15 and 240 min. The textural properties of carbons, before and after nitric acid treatment, were determined using CO2 adsorption at 0 °C. Ammonia adsorption uptakes were measured at 25 °C and at pressures up to 9.5 bar. The highest total uptake of ammonia on the native carbons, that is prior to nitric acid treatment, was ∼10 mmol/g at 1 bar and 25 °C; this was obtained on a microporous carbon derived from the pyrolysis of polyfurfuryl alcohol and polyethylene glycol blends followed by CO2 oxidation. Nitric acid treatment of this carbon significantly increased its total uptake of ammonia to 17 mmol/g. This sample provided a reversible uptake of 14 mmol/g after it was outgassed at 160 °C and 10−5 bar under dynamic vacuum. This is 2 mmol/g higher than state-of-the-art ammonia adsorbents such as COF-10. An x-ray photoelectron spectrum (XPS) showed that the oxygen content of the carbon increased from 3 at.% to 16.4 at.% after the nitric acid treatment. Heats of adsorption profiles, calculated from adsorption isotherms, started from 165 kJ/mol and quickly dropped to 40 kJ/mol with ammonia loading. This showed that the isosteric heat of adsorption on the remaining surface was still higher than the native carbon sample resulting in high reversible adsorption uptake, even after excluding the irreversible adsorption on the very high energy sites.
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      PubDate: 2015-07-21T21:28:53Z
       
  • Mesoporous activated carbons with enhanced porosity by optimal
           hydrothermal pre-treatment of biomass for supercapacitor applications
    • Abstract: Publication date: 1 December 2015
      Source:Microporous and Mesoporous Materials, Volume 218
      Author(s): Akshay Jain, Chaohe Xu, Sundaramurthy Jayaraman, Rajasekhar Balasubramanian, J.Y. Lee, M.P. Srinivasan
      A significant improvement of up to 94% in mesopore area of hydrochar-derived activated carbons (ACs) has been achieved using optimal concentrations of biomass (coconut shell) and chemical activating agent (ZnCl2) during hydrothermal pre-treatment. For the first time, we have demonstrated that stoichiometry can influence hydrochar properties and availability of ZnCl2 for activation which has significant impact on the textural properties of mesoporous activated carbons. Tuning of key process parameters and hydrothermal treatment conditions (ZnCl2:biomass ratios and biomass & ZnCl2 concentrations), together with hydrothermal pre-treatment with H2O2, resulted in BET and mesopore areas up to 2440 m2 g−1 and 1121 m2 g−1, respectively. When the mesoporous carbon was employed as an electrode material in supercapacitors, stable energy density at 7.6 W h kg−1 was observed (90% of 8.5 W h kg−1 @ 0.22 kW kg−1) at a high power density of ∼4.5 kW kg−1, which is one the best performance observed thus far in biomass-derived activated carbons.
      Graphical abstract image

      PubDate: 2015-07-21T21:28:53Z
       
  • Structural single and multiple molecular adsorption of CO2 and H2O in
           zeolitic imidazolate framework (ZIF) crystals
    • Abstract: Publication date: 1 December 2015
      Source:Microporous and Mesoporous Materials, Volume 218
      Author(s): V. Timón, M.L. Senent, M. Hochlaf
      Theoretical methods are used for modelling the capture and storage of CO2 in Zinc-Imidazolate-Frameworks (ZIFs). Density functional theory (DFT) is employed to establish the structure of three ZIFs with small, medium and large cages to predict the uptake behaviour of adsorbed water and carbon dioxide. Water hydration strength and configuration inside the material are investigated with and without the presence of CO2. CO2 is predominantly located around the inner surface of the cages in the ZIFs type ZIFn (n = 1,4,6) through single and multipoint interactions. Water shows a stronger adsorption than carbon dioxide and can play an important role in solvating the CO2 molecules inside the porous. In the final structures, H2O and CO2 do not react with the surface to produce hydroxyl groups or carbonate-like species, respectively. Both species compete for the same adsorption sites. Their maximum adsorption occurs in systems with really accessible surfaces such us ZIF6. A detailed study of the surface-accessibility of a molecule on a “Connolly Surface” is reported, were ZIFs with extra-large pores plays a major role on the adsorption process. Simulated adsorption isotherms throughout MC simulations were obtained for a single CO2 and H2O in which results give a ranking for the most appropriate process conditions.
      Graphical abstract image

      PubDate: 2015-07-21T21:28:53Z
       
  • Compressibility and crystal–fluid interactions in all-silica
           ferrierite at high pressure
    • Abstract: Publication date: 1 December 2015
      Source:Microporous and Mesoporous Materials, Volume 218
      Author(s): Paolo Lotti, Rossella Arletti, G. Diego Gatta, Simona Quartieri, Giovanna Vezzalini, Marco Merlini, Vladimir Dmitriev, Michael Hanfland
      The high-pressure behavior of a synthetic siliceous ferrierite has been studied by in situ single-crystal and powder synchrotron X-ray diffraction with a diamond anvil cell, using four different P-transmitting fluids: the non-penetrating silicone oil and the potentially pore-penetrating methanol:ethanol:H2O = 16:3:1 mixture, ethylene glycol and 2methyl-2propen-1ol. The high-pressure experiment in silicone oil shows a remarkable flexibility of the FER framework. Two displacive phase transitions, following the path Pmnn-to-P121/n1-to-P21/n11 with pressure, were observed. The three polymorphs were found to share a virtually identical bulk compressibility, though showing a different anisotropic pattern. The experiments with potentially penetrating media enhanced the occurrence of a complex scenario, from which the P-induced intrusion of fluid molecules into the FER structural voids can be assumed by the different phase-transition paths and compressibility patterns, by the calculated residual electron density and by the different deformation mechanisms at the atomic scale, observed as a function of the used medium. The starting orthorhombic polymorph was always restored upon decompression in all the experiments. The roles of the different surface area in single crystal and polycrystalline samples, and of the process kinetics on the compressibility and crystal–fluid interactions, are discussed.
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      PubDate: 2015-07-21T21:28:53Z
       
  • Synthesis of hierarchical SAPO-11 via seeded crystallization
    • Abstract: Publication date: 1 December 2015
      Source:Microporous and Mesoporous Materials, Volume 218
      Author(s): Qiuying Wu, Isaac Nartey Oduro, Yong Huang, Yunming Fang
      Hierarchical SAPO-11 molecular sieve was synthesized via a seeded crystallization approach as reported in this paper. SAPO-11 molecular sieve was first synthesized in common Al2O3-P2O5-Dipropylamine-H2O system. Nitrogen adsorption test indicated that the synthesized SAPO-11 has additional mesoporosity with a mesopore volume being 0.09 cm3/g. SEM and TEM analysis indicated the formation of a core (microporous SAPO-11)/shell (mesoporous SAPO-11 aggregate) structure. With the purpose to improve the mesoporosity, SAPO-11 seed was added into the Al2O3-P2O5-Dipropylamine-H2O system. XRD, SEM, TEM, and nitrogen adsorption tests indicated hierarchical SAPO-11 molecular sieve with mesopore volume up to 0.40 cm3/g can be synthesized in Al2O3-P2O5-Dipropylamine-H2O system with 2–10% SAPO-11 molecular sieve as seed. SEM and TEM studies indicate the formation of SAPO-11 nanorods with ultra-small diameter (5 nm). A crystallization kinetic study indicated that 6 h is sufficient for the formation of highly crystalline hierarchical SAPO-11 molecular sieve. The texture and acidity of hierarchical SAPO-11 can be controlled by changing the crystallization time. Based on the experimental results, the formation of hierarchical SAPO-11 is an integrated effect of the burst nucleation and special rod shape of SAPO-11 nanocrystal and the role of SAPO-11 seed is promoted nucleation by increasing the surface area of the liquid–solid interface.
      Graphical abstract image

      PubDate: 2015-07-21T21:28:53Z
       
  • Influence of cryogenic drying conditions on hierarchical porous structure
           of aluminum oxide systems
    • Abstract: Publication date: 1 December 2015
      Source:Microporous and Mesoporous Materials, Volume 218
      Author(s): Katalin Sinkó, Balázs Kobzi, Jeremy Sinclaire, Adrienn Baris, Ottó Temesi
      Highly porous alumina systems were aimed to produce by low energy-consuming sol–gel and freeze drying techniques. A 3D molecular gel structure derived by sol–gel method is provided as a precursor for vacuum freeze drying process. The typical inorganic precursor is an aqueous colloid solution such as sol or suspension. The new type of precursor results in a new columnar pore structure. The porous system keeps their high porosity even above 1500 °C in contrast with the reported heat resistance value (<800–1000 °C) of the porous alumina systems. The effects of the solvent content and other chemical additives as well as the drying conditions were studied on the porous structure. 3D SEM images represent the inner structure of porous materials.
      Graphical abstract image

      PubDate: 2015-07-17T21:28:47Z
       
  • Asymmetric and symmetric occupation of active sites in porous copper(II)
           metal-organic frameworks with their gas absorption
    • Abstract: Publication date: 1 December 2015
      Source:Microporous and Mesoporous Materials, Volume 218
      Author(s): Xiang He, Qian Luo, Kang Fang, Zhiming Duan, Zhanfeng Ju
      Solvothermal synthesis afford two new porous metal-organic frameworks (MOFs): {[Cu6(L)3(H2O)4(py)2]·6(DMF)13(H2O)}n (1) and {[Cu6(L)3(H2O)6]·29(H2O}n (2). [5,5′-(1,3-phenylenebis(methylene))bis(oxy)diisophthalic acid (HL)]. Although possessing similar structures, the two MOFs have markedly different stabilities. Compound 1 and 2 can take up 16.8 mg/g and 15.9 mg/g of H2 at 77 K at 1 bar and 133 cm3/g and 120 cm3/g of H2 at 87 K (Fig. 8), which is higher than the performance of well-known MOFs PCN-6 and HKUST-1 at 77 K and 1 bar. Notably, both MOFs exhibited highly efficient, selective adsorption of CO2 over CH4 under ambient conditions. Such compounds may therefore prove useful for gas separation and purification.
      Graphical abstract image

      PubDate: 2015-07-17T21:28:47Z
       
  • Specific heat capacities of MOF-5, Cu-BTC, Fe-BTC, MOF-177 and MIL-53 (Al)
           over wide temperature ranges: Measurements and application of empirical
           group contribution method
    • Abstract: Publication date: 15 November 2015
      Source:Microporous and Mesoporous Materials, Volume 217
      Author(s): F.A. Kloutse , R. Zacharia , D. Cossement , R. Chahine
      Specific heat capacities of five MOFs: MOF-5, Cu-BTC, Fe-BTC, MIL-53 (Al) and MOF-177 are reported over wide temperature ranges. For MOF-5, which is the primary candidate material down selected by the Hydrogen Storage Engineering Center of Excellence (HSECoE) for cyro-adsorptive vehicular hydrogen storage, specific heat capacity in the range 2–300 K is obtained by combining the measurements using a Calvet calorimeter and a direct adiabatic relaxation calorimeter while for remaining MOFs, C p s are measured in the temperature range 80–320 K using the Calvet calorimeter alone. All MOFs exhibit monotonically increasing specific heat capacities with no visible thermal anomalies implying the absence of any temperature-induced phase transitions in the temperature range considered. A simple ion-based group contribution approach is applied to empirically predict the specific heat capacities of all MOFs at 323 K.
      Graphical abstract image

      PubDate: 2015-07-09T09:01:00Z
       
  • Hierarchical macro- and mesoporous assembly of metal oxide nanoparticles
           derived from metal-organic complex
    • Abstract: Publication date: 15 November 2015
      Source:Microporous and Mesoporous Materials, Volume 217
      Author(s): Chengcheng Liu , Jianling Zhang , Li Peng , Xinchen Kang , Buxing Han , Xinxin Sang , Xue Ma , Guanying Yang
      The hierarchical porous metal oxide combines the advantages of each class of hierarchical pores and has potential applications in different fields. Here we proposed an emulsion-calcination route for producing porous metal oxide. The porous metal-organic complex was first synthesized in CO2-in-water emulsion, then the metal-organic complex was calcined to remove the organic linker and form porous metal oxide. The hierarchical macro- and mesoporous assemblies of Co3O4 nanoparticles were produced. The hierarchical macro- and mesoporous assemblies of Co3O4 nanoparticles were produced, with the macropores in size of hundreds of nanometers and the mesopores in 9–15 nm. The porosity properties and nanoparticle size of Co3O4 can be modulated by controlling CO2 pressure. The as-synthesized Co3O4 is an excellent candidate catalyst for the methylene blue degradation. By taking advantages of the high porosity and small particle size, the Co3O4 have potential applications in catalysis, gas separation, and controlled drug release. The strategy proposed in this work can be applied to the synthesis of different kinds of porous metal oxides.
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      PubDate: 2015-07-09T09:01:00Z
       
  • Growth of MFI zeolite film as corrosion protection layer of aluminum alloy
    • Abstract: Publication date: 15 November 2015
      Source:Microporous and Mesoporous Materials, Volume 217
      Author(s): Lin-Yi Huang , Yuan-Chung Hao , WenChyuan ChangJean , Mei-Jhu Wang , Anthony S.T. Chiang , Tseng-Chang Tsai
      The dry-gel-conversion (DGC) and the in-situ crystallization (InC) for the growth of MFI zeolite films were examined. The combination of DGC method and H2O2 pre-treatment showed the best corrosion protection performance. The corrosion rate was reduced by five orders of magnitude in reference to the bare-substrate in NaCl solutions. Based on the electrochemical spectroscopy, the anti-corrosion property could be attributed to the formation of dense zeolite films and strongly bonded interfacial layers that acting as barrier layers for the protection against corrosive species. The corrosion resistances of the interfacial layer could be upgraded by either the InC or DGC grown MFI zeolite film.
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      PubDate: 2015-07-09T09:01:00Z
       
  • A new carbon–diatomite earth composite adsorbent for removal of
           heavy metals from aqueous solutions and a novel application idea
    • Abstract: Publication date: 15 November 2015
      Source:Microporous and Mesoporous Materials, Volume 217
      Author(s): József Dobor , Katalin Perényi , Imre Varga , Margit Varga
      A new type of carbon coated diatomite earth (DE) composite adsorbent was prepared using cellulose as carbon source. Carbonization and functionalization were studied by various reactants and finally concentrated sulfuric acid was applied in one-step. The procedure resulted in highly functionalized, porous carbonaceous matter. Cellulose was substituted by low-cost material containing cellulose resulting in unremarkable difference in the properties of the composite. The composite was studied among others, by scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) and elemental and correlation map was created by the obtained data. The composite was successfully used to remove heavy metal ions {Pb(II) and Ni(II)} from aqueous solution. The application was performed in both of the closed and flow systems. In closed system, the adsorption process followed the Langmuir isotherm. The adsorption depended on the pH and the highest adsorption capacities were 80 and 380 mg g−1 for Ni(II) and Pb(II) respectively. As a novel application, fractionation solid phase extraction (SPE) technique was applied for investigation of absorption characteristics of the composite in flow system. SEM-EPMA results demonstrated that lead was bonded to C–O bonds on the surface of composite.
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      PubDate: 2015-07-09T09:01:00Z
       
  • Ionothermal synthesis of a CHA-type aluminophosphate molecular sieve
           membrane and its formation mechanism
    • Abstract: Publication date: 15 November 2015
      Source:Microporous and Mesoporous Materials, Volume 217
      Author(s): Xiaolei Li , Keda Li , Huaijun Ma , Renshun Xu , Shuo Tao , Zhijian Tian
      A gas permeable CHA-type aluminophosphate molecular sieve membrane was ionothermally synthesized on a porous δ-alumina substrate through the so-called “substrate surface conversion” method. The synthetic conditions for this specific membrane were optimized. The temperature, time and the amounts of H3PO4 and HF in the initial synthesis solution were investigated. X-ray diffraction (XRD), scanning electron microscopy (SEM) and gas permeation were performed to characterize the entire formation process for the CHA-type molecular sieve membrane. A formation mechanism of the “substrate surface conversion” method was proposed. The transformation of the gel layer to the CHA membrane via a solid transformation mechanism was suggested.
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      PubDate: 2015-07-09T09:01:00Z
       
  • Mesoporous silica nanoparticles capped with fluorescence-conjugated
           cyclodextrin for pH-activated controlled drug delivery and imaging
    • Abstract: Publication date: 15 November 2015
      Source:Microporous and Mesoporous Materials, Volume 217
      Author(s): Xiaofei Chen , Xuemei Yao , Chunran Wang , Li Chen , Xuesi Chen
      Herein, we developed a kind of functionalized mesoporous silica nanoparticles with excellent biocompatibility by using fluorescence-conjugated β-cyclodextrin as acid activated gatekeepers to cap the mesopores of mesoporous silica nanoparticles. One hand, 3-carboxy-5-nitrophenylboronic acid, which served as a linker to connect mesoporous silica nanoparticles and fluorescent β-cyclodextrin, was grafted on the surface of the mesoporous silica nanoparticles. Due to the reversible pH-depended phenyboronates formed between 3-carboxy-5-nitrophenylboronic acid and β-cyclodextrin, this functionalized mesoporous silica nanoparticles showed excellent acid-sensitivity. At neutral aqueous, the functionalized mesoporous silica could accommodate the drug molecules because the mesopores were capped by the gatekeepers, while at acid intercellular environment, the gatekeeper would be removed to release the loaded drug due to the hydrolysis of phenyboronates. On the other hand, the fluorescent agents, fluorescein isothiocyanate, could trace the pathway during the therapy process. In vitro drug release behavior further confirmed that the acid-sensitive gatekeeper could control the release of the loaded-drug by the on-off of the pores. Cell experiment analyses against HeLa and HepG2 cells showed clear evidence that DOX-loaded functional mesoporous silica nanoparticles had enhanced tumor inhibition with monitoring the treatment process, indicating a possible therapeutic application for further biomedical use.
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      PubDate: 2015-07-09T09:01:00Z
       
  • The enhancement of porosity of carbon xerogels by using additives
    • Abstract: Publication date: 15 November 2015
      Source:Microporous and Mesoporous Materials, Volume 217
      Author(s): Natalia Rey-Raap , Sandra Rodríguez-Sánchez , Isabel D. Alonso-Buenaposada , Esther G. Calvo , J. Angel Menéndez , Ana Arenillas
      Resorcinol-formaldehyde carbon xerogels were synthesized by means of microwave heating by using precursor solutions with pH values ranging from 3 to 7 and adding various amounts of sodium sulfate, hexadecyltrimethylammonium bromide and Span80. It was found that the amount of additive that can be introduced depends to a large extent on the final pH of the precursor solution. Characterization of the porous structure of the carbon xerogels thus synthesized demonstrated that their porosity was modified by interactions between the additives and the polymeric structure of the xerogels. It is worth noting that carbonaceous materials with a pore size that could not be obtained by merely modifying the pH could be synthesized by adding different types of additive, with the result that a significant improvement of the porous properties of the carbon xerogels was achieved. The addition of sodium sulfate increased the size of the clusters and pores due to repulsive forces created between the additive and resorcinol anions. Hexadecyltrimethylammonium bromide gave rise to a dense branched structure with pores of a small size attributable to forces of attraction between the cations of the additive and resorcinol anions. In contrast, the presence of Span80 in the precursor solution produced a condensation reaction between the resorcinol and the additive, as a result of which the amount of resorcinol available for the sol–gel reaction was reduced.
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      PubDate: 2015-07-09T09:01:00Z
       
  • Hydrolysis of DCNP (a Tabun mimic) catalysed by mesoporous silica
           nanoparticles
    • Abstract: Publication date: 15 November 2015
      Source:Microporous and Mesoporous Materials, Volume 217
      Author(s): Inmaculada Candel , María D. Marcos , Ramón Martínez-Máñez , Félix Sancenón , Ana M. Costero , Margartita Parra , Salvador Gil , Carmen Guillem , Francisco Pérez-Plá , Pedro Amorós
      The hydrolysis of diethylcyanophosphonate, DCNP (a Tabun simulant) in the presence of mesoporous silica nanoparticles (MSN) has been studied in acetonitrile:water (99.5:0.5 v/v) mixtures using 31P NMR as a suitable technique to follow the DCNP hydrolysis. MSN alone was not capable to induce DCNP hydrolysis, yet MSN in combination with the presence of the bases potassium carbonate, triethylamine or DABCO enhanced DCNP degradation. When MSN was used combined with K2CO3, a hydrolysis of ca. 95% of the initial DCNP after 60 min was observed. In the presence of DABCO, MSN was able to induce the hydrolysis of ca. 90% of DCNP after the same time. However, the DCNP hydrolysis using MSN in the presence of Et3N was lower (ca. 30%). In the absence of nanoparticles, DCNP hydrolysis reached only ca. 30% for K2CO3 and DABCO and ca. 7% for Et3N after 60 min. Moreover, kinetic studies were also carried out with the use of solids MSN-1 and MSN-2 that were obtained by reaction of MSN with K2CO3 or DABCO. After the reaction the solids were isolated by centrifugation, washed with acetonitrile and dried. MSN-1 was able to hydrolyse DCNP in a similar way to that found with the MSN-K2CO3 mixture. However, MSN-2 nanoparticles induced a very low DCNP hydrolysis. From all these studies it was found that the main product of the DCNP hydrolysis is tetraethylpyrophosphate. The presence of diethyl phosphoric acid was also observed but at very low concentration. From kinetic data a catalytic mechanism is proposed.
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      PubDate: 2015-07-09T09:01:00Z
       
  • Designing recyclable Cu/ZrSBA-15 for efficient thiophene removal
    • Abstract: Publication date: 15 November 2015
      Source:Microporous and Mesoporous Materials, Volume 217
      Author(s): Hai-Xin Qi , Shang-Ru Zhai , Zhen-Zhen Wang , Bin Zhai , Qing-Da An
      Adsorptive desulfurization (ADS) is an effective method for the selective capture of thiophenic sulfur compounds, and the ADS capacity of an adsorbent has been demonstrated to strongly depend on the dispersion degree of active species. Herein, series of zirconia-modified SBA-15 (ZrSBA-15) framework with uniformly dispersed Cu sites have been prepared via a urea-assisted homogeneous deposition strategy, aiming for efficient adsorption towards thiophene. The resultant materials were thoroughly characterized by X-ray diffraction (XRD), N2 adsorption–desorption isotherms, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance spectra (DRS) analysis techniques. It was revealed that the Cu species were highly dispersed inside the ordered ZrSBA-15 framework with platelet morphology, rather than aggregation outside the surface, leading to excellent adsorption capacity for thiophene (up to 9.35 mg/g at 50 °C). The adsorption kinetics and isotherm data can be well described by the pseudo-second-order kinetics model and the Langmuir isotherm, respectively. Spent adsorbent can be regenerated by simple heating treatment in N2 at 500 °C, without obvious losing of thiophene adsorption capacity even after eight cycles.
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      PubDate: 2015-07-09T09:01:00Z
       
  • Synthesis of mesoporous alumina with tunable structural properties
    • Abstract: Publication date: 15 November 2015
      Source:Microporous and Mesoporous Materials, Volume 217
      Author(s): Wei Wu , Zhijian Wan , Wan Chen , Mingming Zhu , Dongke Zhang
      Mesoporous aluminas (MAs) with tunable structural properties including BET surface area, pore volume and pore size were successfully synthesized. The synthesis method was based on a sol–gel process via hydrolysis of aluminium isopropoxide associated with non-ionic block copolymer P123 as the structure-directing template in an acidic aqueous system. The MAs were characterized using thermogravimetry – differential thermal analysis (TG-DTA) for decomposition and mass loss characteristics during calcination, X-ray diffraction (XRD) for bulk crystallinity, transmission electron microscopy (TEM) for nano-scale morphology, selected area electron diffraction (SAED) for local crystallinity and N2 adsorption–desorption techniques for porous structural properties. By tailoring the amount of P123 and HNO3 addition, inorganic aluminium precursor Al(NO3)3 doping ratio and calcination temperature, MAs with controllable structural properties were obtained, leading to regular variations in the surface area (up to 409 m2g−1), pore volume (0.4 cm3g−1 ∼ 2.8 cm3g−1) and pore size (5.0 nm ∼ 33.1 nm). Bovine serum albumin (BSA) was employed to evaluate the adsorption capability of the synthesized MAs. It was found that the structural properties of MA had a crucial effect on the BSA adsorption capability, increasing dramatically with increasing surface area, pore volume and pore size. For the sample MA4P15AlN (surface area 287 m2g−1, pore volume 2.8 cm3g−1 and pore size around 33.1 nm), the BSA adsorption amount reached 182.7 mgg−1 in 2 h, higher than other MA samples as well as a silicon based reference sorbent material, SBA-15 (133.3 mgg−1).
      Graphical abstract image

      PubDate: 2015-07-09T09:01:00Z
       
 
 
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