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Journal Cover Microporous and Mesoporous Materials
  [SJR: 1.306]   [H-I: 102]   [6 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1387-1811
   Published by Elsevier Homepage  [2969 journals]
  • Surface structuring of mesoporous materials by controlled synthesis of
           nanocavities
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): Philip Ruff, Stefan Lauterbach, Hans-Joachim Kleebe, Christian Hess
      A process for the creation of uniform nanocavities on the surface of mesoporous materials using atomic layer deposition (ALD) and nanotemplate surface patterning is presented. Prior to grafting the organic nanotemplate, the surface of silica SBA-15 was pre-treated with an ALD coating of one monolayer of TiO2. The templates were then surrounded by Al2O3 as wall material using further ALD treatment. Template removal is achieved at moderate temperatures by reaction with ozone preventing damages to the structure which might occur at higher temperatures. By this approach a homogeneous distribution of uniform nanocavities of conical shape with 1–2 nm diameter, reflecting the size and geometry of the calixarene template molecules, was obtained. To monitor the various steps of the synthesis detailed characterization using N2 adsorption/desorption isotherms, FTIR, UV–Vis, and XP spectroscopy as well as thermal analysis and TEM was applied. Results from FTIR and UV–Vis spectroscopy reveal the successful formation of a covalent template-to-substrate binding, which remains unchanged during wall formation but breaks up during ozone treatment. Supporting XPS and TGA measurements give insight into the changing composition of the modified SBA-15 surface during synthesis and template removal in particular.
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      PubDate: 2016-08-24T14:04:39Z
       
  • Metal-organic frameworks based mixed matrix membranes for pervaporation
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): Zhiqian Jia, Guorong Wu
      Metal-organic frameworks (MOFs)/polymer mixed matrix membranes (MMMs) have great potential in pervaporation separation due to the ease of design and modification of MOFs, along with the compatibility between MOFs and polymer matrix. This article reviews the current status of MOFs MMMs for pervaporation, including polymer (hydrophobicity/hydrophilicity, structure stability), MOFs (stability, hydrophobicity/hydrophilicity, surface functional structure, particles morphology and pores size), mass transfer, and applications (dehydration of organic solvents, removal of dilute organic compounds from aqueous streams, separation of organic-organic mixtures, and membrane reactor). The perspectives and suggestions of MOFs MMMs are given.
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      PubDate: 2016-08-24T14:04:39Z
       
  • Importance of hydrogen for low-temperature detemplation of high-silica MFI
           zeolite crystals
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): Lin Lang, Shuheng Zhao, Junfei Jiang, Wenshen Yang, Xiuli Yin
      Many attempts have been made for template removal from inorganic porous materials at mild temperature (below 350 °C), because high-temperature calcination is attributed as the trigger of the framework damages. In this study, a new two-step method, coupling by low-temperature hydrocracking and oxidation, is proposed for efficient removal of the organic templates in high-silica MFI zeolite crystals of different size at a mild temperature (300 °C). With this approach, unlike in conventional calcination above 400 °C, the pristine zeolite framework is preserved and no coke-like residues are formed, consistently verified by NMR, TGA, and Raman spectra. The reason for this phenomenon is proved as a special propyl-radical- mechanism in H2 atmosphere, indicated by GC measurement and analysis online. This provides an alternative option for the low-temperature detemplation of high-silica microporous materials.
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      PubDate: 2016-08-19T14:00:27Z
       
  • Syntheses of SSZ-39 and mordenite zeolites with
           N,N-dialkyl-2,6-dimethyl-piperidinium hydroxide/iodides: Phase-selective
           syntheses with anions
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): Biswa Nath Bhadra, Pill Won Seo, Jong Won Jun, Jong Hwa Jeong, Tae-Wan Kim, Chul-Ung Kim, Sung Hwa Jhung
      SSZ-39 and mordenite zeolites were obtained from the conversion of zeolite Y in the presence of the same reaction precursors (organic templates, NaOH, water, etc.) under a wide range of reaction conditions. The applied templates were N,N-dialkyl-2,6-dimethyl-piperidinium-OH and -I (alkyl: ethyl or methyl). Curiously, SSZ-39 and mordenite were obtained from hydroxides and iodides, respectively, showing firstly the importance of the anion in the selective crystallization of zeolites. Reactions were also performed at the same set of pH values (achieved by adding small amounts of NaOH to the iodide-based precursors) to investigate the effect of basicity; the results did not vary appreciably with the pH of the synthesis precursors. Based on the phase conversion (MOR – > AEI or ANA with increasing reaction time and pH), the selective formation of SSZ-39 and mordenite from hydroxides and iodides, respectively, could be explained in terms of zeolite-promoting and -preventing anions (hydroxide and iodide, respectively). The phase conversion of zeolites could be explained on the basis of the maximum pore size of zeolites, rather than the framework densities. The obtained zeolites (SSZ-39 and mordenite), in their protonated forms, were employed in ethanol dehydration and direct ethylene-to-propylene conversion, and the results showed that the two zeolites have potential application in acid catalysis. In particular, the SSZ-39 with an AEI structure can be applied in the direct production of propylene from ethylene or ethanol.
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      PubDate: 2016-08-19T14:00:27Z
       
  • Manipulation of the surface microstructure and its effects on the flux of
           NaA zeolite membranes in pervaporation
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): Nanke Ma, Zhiying Zhan, Zhengbao Wang
      NaA membranes with different microstructures are synthesized on macroporous alumina tubes with the addition of crystallization improving agents (CIAs) which have the same composition with the synthesis hydrogel but are aged for a longer time (e.g., 24 h). The as-synthesized membranes are characterized by SEM, contact angle measurement and pervaporation test. It is found that the addition of the CIAs in the synthesis hydrogel has significant influence on the surface roughness of zeolite membrane, resulting in the change of the hydrophilicity and thus flux of the zeolite membrane. Dense NaA membranes with high flux of 4.53 kg m−2 h−1 can be obtained at 100 °C for 3 h with the addition of 10 wt% CIAs in the synthesis hydrogel. The flux is increased by 14% compared with the membrane synthesized at the same condition without CIAs. The surface roughness of the membranes can also be changed by the method of polishing and re-synthesizing with the assist of nano-seeds. After polishing, the flux decreases to 3.83 kg m−2 h−1; however, the flux can be recovered to 4.45 kg m−2 h−1 after re-synthesizing. This study provides a good method to enhance the separation efficiency and indicates that the surface microstructure of membranes influences their pervaporation performance.
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      PubDate: 2016-08-19T14:00:27Z
       
  • Gas transport through mixed matrix membranes composed of polysulfone and
           copper terephthalate particles
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): Piotr Kubica, Aleksandra Wolinska-Grabczyk, Eugenia Grabiec, Marcin Libera, Marcin Wojtyniak, Sylwia Czajkowska, Marian Domański
      In this work gas transport and structural investigations of heterogeneous membranes composed of polysulfone and copper terephthalate (CuTPA) particles are reported. Three types of CuTPA, varying in surface area, pore volume and pore size distribution, as it was shown by nitrogen physisorption, were investigated as membrane fillers. Structural characterization of pure CuTPA and composite membranes was carried out by positron annihilation lifetime spectroscopy, calorimetry, derivatography, electron microscopy, X-ray diffraction and density measurements. CuTPA possessing high porosity was found to increase permeability of heterogeneous membranes to N2, O2, He, CO2. In contrast, permeability decrease was observed for two other types of CuTPA with lower porosity. Additionally, membranes containing highly porous CuTPA were annealed at two different temperatures and it was found that higher temperature results in higher both membrane permeability and selectivity. For example, CO2 permeability for membrane annealed at 150 °C was 1.65-times higher than that for pure PSF, whereas membrane annealed at 200 °C was 3.3-times more permeable. This significant change in membrane permeability was ascribed to residual solvent removal from CuTPA pores.
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      PubDate: 2016-08-19T14:00:27Z
       
  • Metal loaded nanoporous silicas with tailor-made properties through
           hyperbranched polymer assisted templating approaches
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): E.G. Deze, A. Papavasiliou, S.K. Papageorgiou, F.K. Katsaros, E.P. Kouvelos, G.E. Romanos, N. Boukos, Q. Xin, J.L. Nyalosaso, P. Cool
      Over the last years, mesoporous silicas have gathered considerable interest especially in the field of catalysis, singled out as excellent catalytic supports owing to their intriguing textural features. Herein, the synthesis of novel nanoporous silicate materials containing copper or palladium nanoparticles, by means of co-assembly and one-pot templating pathways is described. Inclusion of metal nanoparticles within the porous network of the silicate materials is accomplished with the use of hyperbranched Polyethyleneimines (PEIs), serving both as chelating and secondary structure directing agents. The co-assembly method involves the introduction of PEI into the initial reaction mixture containing the triblock copolymer Pluronic P123 as the main template and TEOS as the silica source, whereas incorporation of metal nanoparticles is performed at a second step. In the one-pot approach, the only difference is that metal loading is carried out in a single step through the direct insertion of PEI already complexed with the desired metal, into the synthetic gel. Several parameters are investigated including solution's pH, reaction path and PEI's molecular weight. Results from TGA, XRD, N2 porosimetry, electron microprobe, SEM, TEM and UV-DR analyses, confirm that both synthetic strategies can produce nanoporous materials with advanced and tunable textural and morphological characteristics and thus widened application prospects. Among the examined synthesis parameters, PEI molecular weight and synthetic gel's pH were found to have the most pronounced effect on final material pore architecture, morphology, metal loading and dispersion. Preliminary deNOx activity tests in the NO + CO reaction indicated that the developed materials could find use in environmental applications.
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      PubDate: 2016-08-19T14:00:27Z
       
  • Use of chabazite, a naturally abundant zeolite, for the investigation of
           the adsorption kinetics and mechanism of methylene blue dye
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): Hamza Aysan, Serpil Edebali, Celalettin Ozdemir, Muazzez Celi̇k Karakaya, Necati Karakaya
      Chabazite, one of the common types of zeolite, was used in our study to remove methylene blue (MB) dye from aqueous solutions. The characterization of chabazite was performed using scanning electron microscope (SEM), Fourier Transform infrared (FTIR), X ray diffraction (XRD), and thermogravimetric-differential thermal analyses TG/DTA. During the experimental study, the effects of some parameters, such as contact time, adsorbent dosage, pH, stirring speed, and concentration, on the removal efficiency of chabazite were taken into consideration. To evaluate the experimental data, Langmuir, Freundlich, and Tempkin isotherm models were used. The experimental data were well fitted to the Langmuir isotherm model, with a correlation coefficient of 0.95. The adsorption kinetics of MB dye on chabazite could be described by a pseudo second-order model.
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      PubDate: 2016-08-15T03:49:35Z
       
  • A novel modelling approach to surface and Knudsen multicomponent diffusion
           through NaY zeolite membranes
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): Alessio Caravella, Pasquale F. Zito, Adele Brunetti, Enrico Drioli, Giuseppe Barbieri
      A novel pairing between Knudsen and surface diffusion is developed for multicomponent mass transport in NaY zeolite membranes considering the actual conditions inside the pores owing to competitive adsorption of the species. The motivation behind this study starts from the consideration that the adsorption of the species, in particular of the most strongly adsorbed ones (like CO2), can significantly influence the Knudsen permeation. This occurs because the pore geometrical parameters affecting permeation, i.e., porosity, tortuosity and mean diameter, are modified by the steric effect owing to the presence of the adsorbed molecules, whose size is close to pore diameter. Therefore, in the present work, all these geometrical parameters are expressed as functions of the adsorption loading. This leads to a model that correctly predicts the blocking effect on the Knudsen diffusion mechanism at a low temperature, where the adsorption strength is sufficiently high to cause a severe occupation of the channel cross-section. As a consequence, such a model allows membrane selectivity to be predicted in a wide range of temperature and pressure. For instance, the CO2/H2 selectivity is observed to change from 25 to 0.3 when the temperature goes from 303 to 673 K. Hence, this novel approach, which is well-validated in both binary- and ternary-mixture conditions, is a useful tool for the analysis of the mass transport of multicomponent mixtures through NaY zeolite membranes, particularly at lower temperatures, where the adsorption strength provides a higher selectivity.
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      PubDate: 2016-08-15T03:49:35Z
       
  • Synthesis of biomass derived levulinate esters on novel sulfated Zr/KIL-2
           composite catalysts
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): Margarita Popova, Ágnes Szegedi, Hristina Lazarova, Alenka Ristić, Yuri Kalvachev, Genoveva Atanasova, Nicole Wilde, Nataša Novak Tušar, Roger Gläser
      Zirconia nanomaterials were prepared by impregnation of KIL-2 type silica with 4, 8, 15 and 25 wt% of ZrO2, and were modified by sulfate groups in order to vary the type, strength and density of the active sites. The samples were characterized by X-ray powder diffraction (XRD), EDX analysis, N2 physisorption, SEM, TEM, UV–Vis spectroscopy, XPS, and thermogravimetric analysis (TGA). The acidic properties were investigated by FT-IR spectroscopy of adsorbed pyridine. The catalytic properties of ZrKIL-2 catalysts and their sulfated varieties were studied in levulinic acid (LA) esterification with ethanol or n-butanol. The sulfated materials showed significantly higher activity compared to the non-sulfated ones due to their stronger Brönsted and Lewis acid sites. It was found that the silica supported sulfated samples show different activity depending on the applied alcohol. With increasing ZrO2 content up to 15 wt% increasing catalytic activity and selectivity was observed to produce levulinate esters. A further increase of the amount of zirconia leads to a decrease in catalytic activity because of the significant decrease of ZrO2 dispersion and the structure deterioration of the catalyst. For the first time insight was provided into the relation between sulfates group leaching and zirconia dispersion.
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      PubDate: 2016-08-10T03:44:32Z
       
  • Use of surface modified natural zeolite (SMNZ) in pharmaceutical
           preparations. Part 2. A new approach for a fast functionalization of
           zeolite-rich carriers
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): Bruno de Gennaro, Mariano Mercurio, Piergiulio Cappelletti, Lilia Catalanotti, Aleksandra Daković, Alberto De Bonis, Celestino Grifa, Francesco Izzo, Milan Kraković, Vincenzo Monetti, Alessio Langella
      Main purpose of the research was to define an operative protocol, applicable at industrial scale, optimizing the functionalization of natural zeolites with surfactants, especially in pharmaceutical and environmental sphere. Three zeolite-rich samples from Italy (PHI_SAV), Slovakia (CLI_SK) and California (CLI_CA) were used for preparation of SMNZ. Two different protocols allowed to carry out surfactant adsorption equilibrium runs and surfactant sorption kinetics by varying different parameters: mixing speed (4000, 6000, and 8000 rpm); contact time (15 ÷ 90 min) and initial surfactant concentration (from 25% to 200% of the external cation exchange capacity - ECEC) at a constant solid/liquid ratio (1 g/50 mL). Zeolite-rich materials were treated with solutions of cetylpiridinium chloride (CP-Cl). The functionalization of SMNZ was obtained by using a high-speed disperser. The amount of absorbed surfactant onto two carriers (CLI_SK and PHI_SAV) was evaluated through kinetic experiments under the following conditions: the initial CP-Cl concentration of 150% of the ECEC and a disperser speed of 8000 rpm. Results showed that after 15 min, equilibrium was attained with the adsorbed amount of about 0.14 meq/g of CP-Cl (equivalent to the ECEC of the investigated zeolitic support), confirming formation of monolayer (emi-micelle). The functionalization (micelle formation) of two samples occurred after 70 min of solid/liquid interaction with a total yield equal to 150% of the ECEC, thus indicating formation of a patchy bilayer. By contrast, CLI_CA behaves completely differently since the formation of emi-micelle was achieved only at much higher speed (18000 rpm) and not earlier than 90 min of mixing.
      Graphical abstract image

      PubDate: 2016-08-10T03:44:32Z
       
  • Dynamic measurements and wettability phenomena in mesoporous anodic films
           prepared on 1050 and 2024T3 aluminium alloys
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): Kévin Giffard, Laurent Arurault, Christine Blanc
      The wettability of mesoporous anodic films has until now been a parameter rarely studied although it remains crucial especially for sealing treatment following anodising. Wettability measurement is in fact complex as it depends on a number of process parameters relating to the three phases (mesoporous anodic film, deposited liquid and ambient gas). In the present study, an innovative experimental approach was first adopted involving measuring the characteristics of a deposited water drop (contact angle, chord length and height of the drop) in relation to time. Following this, a flow balance allowed the amount of water having infiltrated the mesopores to be determined for two types of anodic film, one tortuous (on an AA 2024T3 substrate), the other not (on an AA 1050 substrate). On the basis of models already available in the literature, a phenomenological mechanism (spreading, penetration and evaporation) was finally proposed and discussed especially with respect to the tortuosity and prior drying of mesoporous anodic films.
      Graphical abstract image

      PubDate: 2016-08-10T03:44:32Z
       
  • The importance of electrode characterization to assess the supercapacitor
           performance of ordered mesoporous carbons
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): Ángela Sánchez-Sánchez, Teresa A. Centeno, Fabián Suárez-García, Amelia Martínez-Alonso, Juan Manuel D. Tascón
      Carbon based-supercapacitors are widely used in numerous applications but the knowledge of the specific role of carbon features in their performance is still insufficient. The main aim of this work is to warn readers that the current interpretation of the device operation, mostly based on powdered carbon properties, may be misleading in certain cases and should be complemented with the physicochemical characterization of the corresponding electrodes. Ordered mesoporous carbons highly enriched in surface functionalities were prepared by carbonization of 3-aminobenzoic acid into SBA-15 template. These carbons achieved a specific capacitance as high as 220 F/g in 2 M H2SO4 aqueous electrolyte. The pseudocapacitance contribution ranged between 35 and 70% of the overall capacitance. It was shown that the structural and textural changes underwent by these advanced carbons during their processing in form of electrodes prevented the full exploitation of their outstanding properties for high-power applications. This makes a difference regarding conventional, disordered activated carbons, which virtually preserve their structure during electrode preparation.
      Graphical abstract image

      PubDate: 2016-08-10T03:44:32Z
       
  • High-pressure behavior of HEU-type zeolites: X-ray diffraction study of
           clinoptilolite-Na
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): Yurii V. Seryotkin
      Clinoptilolite-Na, Na2.55Ca1.67K0.37(H2O)21.5[Al6.21Si29.79O72], with the space group C2/m, a = 17.6229(4), b = 17.9957(3), c = 7.39625(15) Å, β = 116.353(3)°, V = 2101.85(7) Å3, and Z = 1 has been studied by single-crystal X-ray diffraction method in normal conditions as well as under compression in penetrating (water-containing) and non-penetrating (paraffin) media. When compressing in water medium, clinoptilolite is subjected to the additional hydration at the starting stage unlike the structurally similar heulandite with persistent increasing the content of H2O over the wide pressure range. This occurs owing to the additional population of partially vacant positions. With further increasing the pressure, H2O molecules are redistributed in the extraframework subsystem saving the total number. Both literature and our data on compression of zeolites of the isomorphous heulandite-clinoptilolite series in non-penetrating media evidence that the compressibility along the coordinate directions noticeably differs from sample to sample including differences in the direction of the largest compression. This is evidently associated with variations in the zeolite composition.
      Graphical abstract image

      PubDate: 2016-08-10T03:44:32Z
       
  • Mineralogical characterization of zeolites present on basaltic rocks from
           Combia geological formation, La Pintada (Colombia)
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): J.F. Gelves, G. Sierra Gallego, M.A. Marquez
      The present study report the presence of natural zeolites, which were found in the andesitic basalts from the Combia geological formation, municipality of La Pintada, Antioquia department (Colombia). The collected samples were characterized using X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy with detector X-ray energy dispersive (SEM/EDX), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and polarized light optical microscopy (PLOM). The results shown the presence of an associated zeolites heulandite group with predominance of heulandite phase rich in calcium and potassium, with prevalence of platy habit and in a lesser extent the habit coffin type, tabular and block were also evidenced. The presence of chabazite, phillipsite and mordenite, were evidenced as minority zeolites phases. Based on the zeolites properties, the phases founded in Combia formation could be an interest materials for technological applications in areas such agriculture, catalysis or gas separation applications. Especially in Colombia this kind of mineral can be important because much of the current consumption is imported from other territories.
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      PubDate: 2016-08-10T03:44:32Z
       
  • Methane in zeolitic imidazolate framework ZIF-90: Adsorption and diffusion
           by molecular dynamics and Gibbs ensemble Monte Carlo
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): Vo Thuy Phuong, T. Chokbunpiam, S. Fritzsche, T. Remsungnen, T. Rungrotmongkol, C. Chmelik, J. Caro, S. Hannongbua
      There is experimental evidence from adsorption and permeation studies that methane can enter the Zeolitic Imidazolate Framework (ZIF)-90 framework despite the fact that the critical diameter of methane (3.8 Å) is larger than the window size of ZIF-90 (3.5 Å) assuming a rigid framework. Therefore, adsorption and diffusion of methane in the ZIF-90 were investigated by Molecular Dynamics (MD) and Gibbs Ensemble Monte Carlo. Various interaction force fields have been tested and a suitable one has been proposed. Results of structural and dynamical properties of methane in ZIF-90 are presented. Like for methane in ZIF-8, no gate opening was found in this paper for methane in ZIF-90 up to a pressure of 260 bar. Therefore, the adsorption and diffusion of methane in ZIF-90 can be explained by a flexible framework.
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      PubDate: 2016-08-10T03:44:32Z
       
  • Protein encapsulation in SBA-15 with expanded pores
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): P.R.A.F. Garcia, R.N. Bicev, C.L.P. Oliveira, O.A. Sant’Anna, M.C.A. Fantini
      This work reports the encapsulation of proteins with different molecular weights into SBA-15 ordered mesoporous silica, a potential immunological adjuvant. The Human Gammaglobulin G (HGG) and Bovine Serum Albumin (BSA) proteins were incorporated into the mesoporous silica with expanded pores. A structure swelling agent, triisopropylbenzene (TIPB), was used in the synthesis process, promoting an increase of the average pore diameter and a more disordered pore network, as revealed by nitrogen adsorption isotherm (NAI) and small angle X-ray scattering (SAXS) data. SAXS measurements were also performed to obtain the overall size of the studied proteins. The results showed that both proteins have dimensions that would allow their encapsulation inside the pores of SBA-15. The HGG and BSA proteins were dissolved in phosphate buffered saline (PBS) solutions before encapsulation. It was evidenced the filling of the micropores by the PBS solution and a larger variation in pore volume and surface area for the material with higher mean pore diameter, which was also confirmed by the modeling of SAXS data. It was not observed any significant difference in the SAXS and NAI results of both proteins, indicating that the immunogens could be encapsulated in the silica macroporosity, obstructing the mesopore entrances.
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      PubDate: 2016-08-10T03:44:32Z
       
  • Synthesis of porous carbon from petroleum coke using steam, potassium and
           sodium: Combining treatments to create mesoporosity
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Luis D. Virla, Vicente Montes, Jingfeng Wu, Stephanie F. Ketep, Josephine M. Hill
      Bitumen upgrading involves the hydroconversion of larger molecules that require catalyst supports with meso- and/or macropores for access to the active sites. In this study, various activation processes were studied to activate delayed petroleum coke, which is a by-product of oil sands bitumen upgrading and an inexpensive source of carbon. The petroleum coke was subjected to steam, chemical (KOH, NaOH) and combined activation methods at 973 K and 1073 K. The produced materials were characterized with nitrogen physisorption at 77 K and scanning electron microscopy. Combined with the yields, the results suggested that the combination of steam with sodium or potassium increased the mesoporosity of the carbon samples possibly by a catalytic gasification mechanism. A mesopore volume of 0.39 cm3/g with a yield of 27% was achieved by simultaneously activating with sodium and steam. Washing the material after activation with sodium and before introducing steam produced the same mesoporosity but doubled the yield, confirming that steam alone is not effective at creating porosity. The accessibility of the larger pores was confirmed with the adsorption of asphaltenes from Athabasca extra-heavy crude oil. The capacity for asphaltene adsorption increased with increasing mesopore volume.
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      PubDate: 2016-07-31T06:09:07Z
       
  • High-performance supercapacitor based on nanocages with nanoporous
           thin-walled graphitic shells
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Zhao Min Sheng, Ming Hui Hu, Xian You Dai, Cheng Yang Hong, Cheng Kang Chang, Qi Zhong Chen, Xin Jian Chang
      Thin-walled graphitic nanocages (GNCs) made up from highly nanoporous shells have been prepared by removing nitrogen-doping (N-doping) template. N-doping template is carboxyl groups and nitro-groups, which have formed from oxidation of N-doped structure of GNCs by acid-treatment. After partially removing N-doping template by annealing in vacuum, nanopores are created in the shells of the thin-walled GNCs. Thus, their specific surface area (1100 vs. 700 m2 g−1) and specific capacitance (370 vs. 300 F g−1 at current density of 0.1 A g−1) are sharply raised. With current density increasing to 1 A g−1, the capacitance of the GNCs is still high (230 F g−1), indicating such GNCs is a superb electrode material of supercapacitor.
      Graphical abstract image

      PubDate: 2016-07-31T06:09:07Z
       
  • The influence of modification methods on the catalytic cracking of LPG
           over lanthanum and phosphorus modified HZSM-5 catalysts
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): N. Rahimi, D. Moradi, M. Sheibak, E. Moosavi, R. Karimzadeh
      In the present study, the effect of various modification methods on the activity of ZSM-5 modified catalysts has been studied in catalytic cracking (CC) of LPG. Lanthanum (La) has been loaded in HZSM-5 catalyst using ion exchange, and wet impregnation, and phosphorus (P) has been introduced by wet impregnation and dry impregnation methods. Physico-chemical properties of modified samples were evaluated by using XRF, ICP-OES, XRD, FT-IR, physical N2 adsorption and NH3-TPD characterization methods. Studying the catalytic performance of the samples revealed that wet impregnation could result in better efficiency than dry impregnation and ion-exchange methods. Afterwards, the dual site catalysts containing both La and P have been prepared using wet impregnation and physical mixture processes. It was found that HZSM-5 catalyst modified by successive wet impregnation of La and P could led to the higher conversion and yield of light olefins (ethylene + propylene) compared to the other samples. At the reaction temperature of 650 °C and GHSV of 433 ml min−1/gcat over the mentioned catalyst (in the presence of N2) yield of total light olefins and selectivity was acquired to be 51% and 62%, respectively.
      Graphical abstract image

      PubDate: 2016-07-31T06:09:07Z
       
  • Highly stable In-SBA-15 catalyst for vapor phase Beckmann rearrangement
           reaction
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Rawesh Kumar, Sneha Shah, Jitendra Bahadur, Yuri B. Melnichenko, Debasis Sen, S. Mazumder, Chathakudath P. Vinod, Biswajit Chowdhury
      The Indium doped SBA-15 material was prepared by sol-gel method and tested for vapor phase Beckman rearrangement reaction. Among three indium loading, In/Si ratio of 2/100 was found as an optimum composition in terms of caprolactam selectivity (100%) and cyclohexanone oxime conversion (100%). The catalysts were characterized by N2 adsorption, small-angle X-rays/neutron scattering (SAXS/SANS), XRD, FESEM, HRTEM, EDX, UV, FTIR and NH3-TPD techniques. In-situ SANS experiment was performed on the adsorption of CO2 to detect the micropores in the mesopore wall. All catalysts samples have highly ordered hexagonal structure with well dispersed indium in the silica matrix. The fine tuning of weak and strong acid sites were found in indium doped SBA-15 (In/Si = 2/100) catalyst. The same catalyst showed optimum catalytic performance, high space time yield 114.4 mol/h/gcat and high stability till 6 h of reaction without deactivation. The micro-kinetic analysis showed that there were no external and internal diffusion limitations in the SBA-15 catalyst. The reaction mechanism of Beckmann rearrangement over In-SBA-15 has been elucidated.
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      PubDate: 2016-07-31T06:09:07Z
       
  • Synthesis of ZIF-8 and ZIF-67 using mixed-base and their dye adsorption
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Yu Li, Kang Zhou, Ming He, Jianfeng Yao
      ZIF-8 and ZIF-67 were prepared by using mixed-base ammonium hydroxide and triethylamine (TEA). These two bases could promote the ZIF synthesis, and the yields are significantly improved. The texture structure and morphologies of ZIF prepared with mixed-base also have obvious changes. Three typical dyes, neutral rhodamine B (RB), anionic methyl orange (MO) and cationic methylene blue (MB), were examined for the dye adsorption by using various ZIFs. ZIF-8 and ZIF-67 prepared with TEA have enhanced RB adsorptions that are 2.3–3.8 times of those prepared without TEA, and ZIF-8 exhibited better adsorption performance than ZIF-67. For MO adsorption, ZIF-67 crystals have better adsorption performance than ZIF-8, and ZIF-67 prepared with TEA has a decreased MO adsorption. For MB adsorption, the addition of TEA does not change the MB adsorption for both ZIF-8 and ZIF-67.
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      PubDate: 2016-07-31T06:09:07Z
       
  • Optimisation of SBA-15 properties using Soxhlet solvent extraction for
           template removal
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Simone G. de Ávila, Luís Carlos C. Silva, Jivaldo R. Matos
      Surfactants are utilised as templates in the synthesis of mesoporous materials. Normally, they are removed using a calcination process, however, careful removal is necessary to conserve the properties of the material. This work proposed surfactant removal from SBA-15 mesoporous silica using a Soxhlet extractor and different solvents. The thermal decomposition of the template was studied in order to understand the process of calcination of SBA-15. The results show that the calcination process influences the properties of the material. All of the utilised solvents enabled the removal of template. Some solvents such as water, acetonitrile and dichloromethane promoted template removal primarily from the surface of the material and others such as ethanol, acetone and methanol promoted the removal of template from within the porous silica. All samples were calcined after the extraction process, however the properties of the resulting materials were different. The greater the template removal, the greater was the surface area and pore size of the materials. Increased pore size caused decreased wall thickness. Methanol was the best of the studied solvents in terms of template removal. The extraction time required was studied and 6 h was necessary to complete the process. Soxhlet extraction is not efficient for the complete removal of template from mesoporous materials. However, the reduced quantity of template in the matrix means that less aggressive calcination is required, and therefore the properties of the mesoporous material can be preserved.
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      PubDate: 2016-07-31T06:09:07Z
       
  • Coexistence of sorption behavior and magnetic property in heterometallic
           cluster-based frameworks
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Qipeng Li, Panpan Yu, Jiagang Luo, Jinjie Qian
      Based on the Bifunctional Method, a new heterometallic cluster-based framework (FJI-7) with the coexistence of Cu4I4 cluster and binuclear [(Dy)2(COO)3(DMF)2], has been successfully synthesized and structurally characterized. This FJI-7 structure exhibits a 3-dimensional framework with Lewis basic pyridinyl sites and magnetic centre simultaneously. Additionally, its sorption behavior and magnetic property are also investigated.
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      PubDate: 2016-07-31T06:09:07Z
       
  • Engineering of silica-supported platinum catalysts with hierarchical
           porosity combining latex synthesis, sonochemistry and sol-gel process
           – I. Material preparation
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Andrés Felipe Sierra Salazar, Tony Chave, André Ayral, Sergey I. Nikitenko, Vasile Hulea, Patricia J. Kooyman, Frans D. Tichelaar, Siglinda Perathoner, Patrick Lacroix-Desmazes
      A novel catalyst preparation procedure is proposed in order to enhance the noble metal distribution at low loadings, while controlling the hierarchical porosity of the support material. Thus, a silica-supported platinum catalyst with hierarchical porosity was prepared using a combination of three processes performed in aqueous medium: emulsion polymerisation, sonochemistry and sol-gel synthesis. First, a polystyrene latex template of ca. 130 nm was synthesised by emulsion polymerisation and subsequently decorated with Pt nanoparticles of ca. 2.1 nm by sonochemical reduction of sodium tetrachloroplatinate. Then, the mesoporous silica support was prepared by a two-step acid-base catalysed sol-gel synthesis around the Pt-loaded latex spheres. Materials with specific surface areas and total pore volumes as high as 615 m2 g−1 and 0.74 cm3 g−1, respectively, were obtained.
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      PubDate: 2016-07-31T06:09:07Z
       
  • Preparation of hierarchically mesoporous silica microspheres with ordered
           mesochannels and ultra-large intra-particulate pores
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Wei Wang, Tao Li, Ke Ye, Hai B. Long, Xu Wang, Hongqiang Ru
      In this work, hierarchically mesoporous silica (HMS) microspheres with ordered mesochannels and ultra-large intra-particulate pores are for the first time prepared via a ternary nonionic surfactant templating system (TEOS/P123/HCl(aq.)). Several crucial experimental parameters pertaining to the employed partitioned cooperative self-assembly process and their roles in shaping the mesostructures and morphology were investigated. It was found that relatively low synthesis temperatures, optimal at 36 °C, lead to much improved meso-ordering in the 1st mode mesostructures, while partitioned addition combinations of silica precursor (e.g., 6/4 combination) at such temperatures show to play an important role in inducing spherical particle morphology. By simply increasing the hydrothermal treatment (HTT) temperature up to 140 °C, enhanced porosity together with ultra-large intra-particulate pores can be obtained without compromising meso-orderings, depending mainly on the HTT induced mesostructural transformation process. Higher HTT temperature causes the fragmentation in the 1st mode mesostructures and disappearance of meso-orderings. The resultant micro-sized HMS spheres reveal certain clew-like features: the ‘yarns’ comprise bundles of ordered mesochannels (1st mode mesopores, ca. 8–12 nm), while the 2nd mode intra-particulate pores (ca. 33–128 nm in sizes) exist between the intertwined ‘yarns’. Such HMS microspheres with tunable porous structures might find some interesting applications in chromatographic separations and controlled delivery, etc.
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      PubDate: 2016-07-31T06:09:07Z
       
  • Highly selective and effective removal of uranium from contaminated
           drinking water using a novel PAN/AgX/ZnO nanocomposite
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): H.R. Shakur, Kh. Rezaee Ebrahim Saraee, M.R. Abdi, G. Azimi
      A novel PAN/AgX/ZnO nanocomposite was synthesized and used for the removal of uranium ions from contaminated waters. NaX nanozeolite was successfully synthesized using the hydrothermal technique. Ion exchange method was used to modify it by Ag+ cations. Then ZnO nanoparticles were loaded on the AgX nanozeolite by the ion exchange method which was followed by a calcinations process. Various characterization methods such as X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transforms infrared spectroscopy (FT-IR), and atomic absorption spectroscopy (AAS) were utilized to analyze the synthesized absorbents including bulk NaX zeolite, NaX nanozeolite, and PAN/AgX/ZnO nanocomposite. The experiments of uranium adsorption were conducted at different solution temperatures, contact times, initial uranium ion concentration and adsorbent dose by using batch method. Results showed that the novel PAN/AgX/ZnO adsorbent had a better adsorption performance rather than the micro and nano sized NaX zeolite. This demonstrated the immense potential of newly synthesized adsorbent as an alternative adsorbent for heavy metal ion remediation in polluted waters and wastewaters.
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      PubDate: 2016-07-31T06:09:07Z
       
  • A novel red emitting material based on polyoxometalate@periodic mesoporous
           organosilica
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Carlos M. Granadeiro, Susana O. Ribeiro, Anna M. Kaczmarek, Luís Cunha-Silva, Pedro L. Almeida, Sandra Gago, Rik Van Deun, Baltazar de Castro, Salete S. Balula
      The first lanthanopolyoxometalate-supported bifunctional periodic mesoporous organosilica (BPMO) composite is here reported. The incorporation of decatunsgstoeuropate anions ([Eu(W5O18)2]9−) within the porous channels of an ethylene-bridged TMAPS-functionalized BPMO produced a luminescent material exhibiting a strong red emission under UV irradiation. Photoluminescence studies showed an efficient energy transfer process to the lanthanide emitting center in the material (antenna effect). A significant change in the coordination environment of Eu3+ ions was observed after its incorporation into the TMAPS-functionalized material. The possible reason for this is discussed within the paper.
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      PubDate: 2016-07-31T06:09:07Z
       
  • A novel CoFe layered double hydroxides adsorbent: High adsorption amount
           for methyl orange dye and fast removal of Cr(VI)
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Faling Ling, Liang Fang, Yi Lu, Jiemei Gao, Fang Wu, Miao Zhou, Baoshan Hu
      CoFe-nitrate-layered double hydroxides (LDHs) with Co2+/Fe3+ molar ratios of 2, 3 and 4 were synthesized by a simple co-precipitation method. The as-prepared CoFe-LDHs exhibited a high adsorption activity to the methyl orange (MO) dye and Cr(VI). The adsorption characteristics including adsorption kinetics and isothermals were investigated. Structure analysis of the as-synthesized LDHs before and after adsorption revealed that adsorption proceeds in two processes: external surface adsorption and interlayer anion exchange. The results of MO adsorption experiments showed that LDHs with Co2+/Fe3+ molar ratios of 4 worked best with the largest MO adsorption amount up to 1290 mg/g at an initial concentration of 300 mg/L due to the porous structures. We have also noted that Cr(VI) in a range of 2–25 mg/L can be quickly removed with the maximum adsorption capacity of 27.62 mg/g in the initial 5 min, much faster than other LDH materials. Therefore, CoFe-LDHs are potential cost-effective adsorbents for both MO dye and Cr(VI).
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      PubDate: 2016-07-31T06:09:07Z
       
  • Investigating the interaction of two asymmetric dioxins with FAU 13X
           zeolites using calorimetry and solid-state NMR
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): M. Ben Abda, O. Schäf, F. Ziarelli, H. Pizzala, R. Denoyel, S. Viel, Y. Zerega
      We report on the characterization of dioxin adsorption, notably 2,3-DCDD and 1,2,3,4-TeCDD, from isooctane onto zeolite FAU 13X Na+ and FAU 13X La3+, with 80% Na+- La3+ exchange level. Adsorption isotherms showed extreme affinities of 2,3-DCDD towards FAU 13X Na+ and 1,2,3,4-TeCDD towards FAU 13X La3+ in the experimentally accessible concentration range, which is limited by dioxin solubility in isooctane. Thermogravimetric studies were employed to understand the effect of water content level of zeolites onto the affinity and capacity of adsorption, but also to determine the temperature range of eventual dioxin regeneration. Moreover, microcalorimetric investigations indicated that high dioxin adsorption affinities of 2,3-DCDD towards FAU 13X Na+ and 1,2,3,4-TeCDD towards FAU 13X La3+, respectively, were combined with quite different levels of adsorption enthalpies. Cross polarization magic angle spinning (CP-MAS) NMR experiments recorded with dynamic nuclear polarization (DNP) revealed that 1,2,3,4-TeCDD was adsorbed simultaneously with isooctane in the micropores of the zeolites, without chemical alteration.
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      PubDate: 2016-07-31T06:09:07Z
       
  • Porous nanoclay polysulfone composites: A backbone with high pore
           accessibility for functional modifications
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Tom Felbeck, Alexander Bonk, Gina Kaup, Simon Mundinger, Thomas Grethe, Maike Rabe, Ulrich Vogt, Ulrich Kynast
      Microporous, highly charged and cation exchangeable clays are interesting carriers not only for various functional molecules such as cationic dyes, surfactants, proteins, drugs and complexes, but also for water insoluble molecules. In water, swellable nanohectorite derivatives (“laponites”) with dimensions of about 25 nm in diameter and 1 nm in height delaminate to form individual nanoparticles, which proved to be very useful for applications in aqueous dispersions, but less advantageous for the use in filter systems for water treatment, membrane technology, or as catalysts. To immobilize the particles in aqueous environments and still provide accessibility and high cation exchange rates on the clays, we used an inversion process to prepare porous nanoclay polysulfone composites with high clay contents up to 60%. Successful incorporation of the clays in the matrix required clay pre-modifications with reactive silanes such as octyltriethoxysilane or octadecyltriethoxysilane. Interestingly, unmodified laponite can also be used as a template to form a porous polysulfone network due to its leakage in the inversion process. The high accessibility and activity found in composites prepared with a mixture of unmodified and modified laponite particles pave the way for further modifications with functional molecules for various applications. In this study, we characterize the nanoclay polysulfone composites via scanning electron microscopy, nitrogen gas adsorption of the dried composite, and we determine the cation exchange capacity in the wetted state.
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      PubDate: 2016-07-25T06:00:43Z
       
  • Synthesis of aluminum-containing hierarchical mesoporous materials with
           columnar mesopore ordering by evaporation induced self-assembly
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Mert Kurttepeli, Roel Locus, Danny Verboekend, Filip de Clippel, Eric Breynaert, Johan Martens, Bert Sels, Sara Bals
      The incorporation of aluminum into the silica columns of hierarchical mesoporous materials (HMMs) was studied. The HMMs were synthesized by a combination of hard and soft templating methods, forming mesoporous SBA-15-type silica columns inside the pores of anodic aluminum oxide membranes via evaporation induced self-assembly (EISA). By adding Al-isopropoxide to the EISA-mixture a full tetrahedral incorporation of Al and thus the creation of acid sites was achieved, which was proved by nuclear magnetic resonance spectroscopy. Electron microscopy showed that the use of Al-isopropoxide as an Al source for the HMMs led to a change in the mesopore ordering of silica material from circular hexagonal (donut-like) to columnar hexagonal and a 37% increase in specific surface (BET surface). These results were confirmed by a combination of nitrogen physisorption and small-angle X-ray scattering experiments and can be attributed to a swelling of the P123 micelles with isopropanol. The columnar mesopore ordering of silica is advantageous towards the pore accessibility and therefore preferential for many possible applications including catalysis and adsorption on the acid tetrahedral Al-sites.
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      PubDate: 2016-07-25T06:00:43Z
       
  • Selective Ce(III) ion-imprinted polymer grafted on Fe3O4 nanoparticles
           supported by SBA-15 mesopores microreactor via surface-initiated RAFT
           polymerization
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Yan Liu, Jian Qiu, Yinhua Jiang, Zhanchao Liu, Minjia Meng, Liang Ni, Changchun Qin, Jianbo Peng
      Ce(III) ion-imprinted polymer (Ce(III)-IIP) grafted on Fe3O4 nanoparticles supported by SBA-15 mesopores microreactor was successfully synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization for selective removal of Ce(III) from aqueous solution. The characterization results suggest that the surface ion-imprinted polymer (IIP) synthesized by RAFT is a thin layer. Adsorption isotherm experiments indicated that Redlich-Peterson isotherm model best fitted the experimental data and the adsorption capacity of IIP was obviously higher than that of non-imprinted polymers (NIP) at the same conditions. The kinetics of adsorption followed the Thomas model. Moreover, competitive adsorption studies illustrated that Ce(III)-IIP offers the advantages of selectivity towards Ce(III) compared with NIP even in the presence of other metal ions. All above results indicated the potential application of Ce(III)-IIP for selective removal of Ce(III) from aqueous solution.
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      PubDate: 2016-07-25T06:00:43Z
       
  • Oxo-vanadium immobilized on L-cysteine-modified MCM-41 as catalyst for the
           oxidation of sulfides and oxidative coupling of thiols
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Nourolah Noori, Mohsen Nikoorazm, Arash Ghorbani-Choghamarani
      In the present work, we report for the first time synthesis of oxo vanadium complex containing L-cysteine (CysVO) anchored to mesoporous silica MCM-41. The resultant MCM-41 supported CysVO complex (VO@MCM-41-Cys) was characterized by various physico-chemical techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy and inductively coupled plasma (ICP). It was exhibited that the (VO@MCM-41-Cys) can act as an efficient heterogeneous catalyst in the oxidation of various sulfides into sulfoxides in the presence of hydrogen peroxide (H2O2) as oxidant and oxidative coupling of thiols into disulfides under neat conditions at room temperature. Moreover, ease of recovery and reusability up to 7 consecutive cycles without a significant loss of its catalytic activity, makes the present protocol beneficial from environmental and industrial viewpoint.
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      PubDate: 2016-07-25T06:00:43Z
       
  • Synthesis of mesoporous carbons with narrow pore size distribution from
           metal-organic framework MIL-100(Fe)
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Xinlong Yan, Yingli Yang, Xiaoyan Hu, Min Zhou, Sridhar Komarneni
      Mesoporous carbon materials are of great interest in the field of environmental applications, gas separation and storage, electrode materials for fuel cells, batteries, and etc. Here, we report the synthesis of mesoporous carbons with Fe or Fe3C embedded via carbonization of furfuryl alcohol impregnated metal-organic framework, MIL-100(Fe). The produced carbon materials are featured by nano sheet-like structure, reasonably high specific area (376 m2/g) and narrow mesopore size distribution (centered at around 4.0 nm).
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      PubDate: 2016-07-25T06:00:43Z
       
  • Binary supercritical CO2 solvent mixtures for the synthesis of 3D
           metal-organic frameworks
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Ana López-Periago, Pedro López-Domínguez, Jorge Pérez Barrio, Gerard Tobias, Concepción Domingo
      Efficient and sustainable synthesis of MOFs, as nano or microcrystalline powder, is crucial for the development of new applications for these compounds. For this purpose, the synthesis of Zn2+, Cu2+ and Fe3+-based MOFs was attempted in this study by using a binary medium consisting of supercritical CO2 mixed with an ionic liquid (emimBF4 or emimBr). In comparison with conventional solvothermal and ionothermal synthesis, MOFs were herein obtained under mild reaction conditions, i.e. 200 bar and 65 °C, after relatively short reaction periods (<10 h). To explore the described synthesis method as a generic procedure for the preparation of three-dimensional MOFs, different linkers of the imidazole and carboxylic acid families were tested. Widely investigated MOFs, such as ZIF-8 and HKUST-1, were prepared along with the complex mesoporous MIL-100(Fe). The structure and composition of the synthesized materials were determined by X-ray powder diffraction and elemental analysis. N2 adsorption at low temperature was used to assess the textural properties.
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      PubDate: 2016-07-25T06:00:43Z
       
  • Activated carbon fiber composites for gas phase ammonia adsorption
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Weihua Zheng, Jingtian Hu, Sammuel Rappeport, Zhen Zheng, Zixing Wang, Zheshen Han, James Langer, James Economy
      Low–cost activated carbon fiber composites (ACFCs) were explored as the basis for a system to remove NH3 from the gas phase. ACFCs were synthesized by chemically activating a phenolic precursor on a glass fiber substrate using ZnCl2 as catalyst. Additionally, ACFCs were oxidized with concentrated nitric acid at both room temperature and 83 °C to increase the density of surface oxygen groups. Commercially available phenolic-based physically activated carbon fibers were also oxidized under the same condition as a benchmark. Both physical properties and surface chemical properties of these materials were characterized using SEM, BET, elemental analysis, FTIR, XPS, and Boehm titration. Dynamic flowthrough NH3 adsorption was measured at 500 ppm, at both 0% and 50% relative humidity. Results suggest ACFCs exhibit high surface area, rich oxygen functional groups, with post-treatment further improving surface oxygen content. ACFCs displayed fast sorption kinetics and high NH3 adsorption capacity up to 50 mg/g. Acidic oxygen groups at the surface are correlated with ammonia adsorption. A new anhydride-based reaction mechanism was identified and is proposed, collectively with carboxylic acid functional groups, as being primarily responsible for retaining NH3.
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      PubDate: 2016-07-25T06:00:43Z
       
  • Synthesis of mesoporous La2Zr2O7 with high surface area by combining
           epoxide-mediated sol-gel process and solvothermal treatment
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Shengxue Wang, Wei Li, Song Wang, Zhaohui Chen
      Mesoporous La2Zr2O7 was successfully prepared by combining epoxide-mediated sol-gel process and solvothermal treatment. The gelation was controlled by addition of propylene oxide to the ethanol solutions of nitrates. Solvothermal treatment was adopt to strengthen the mesopore structure and inhibit the collapse of pores during abiment pressure drying, and it obviously increased surface area. The as-synthesized mesoporous La2Zr2O7 showed nanoparticles assembling and mesoporous structure, and the nanoparticles has a surface area of 302.9 m2/g and an average pore size of 22.2 nm. The mesoporous La2Zr2O7 has an amorphous structure with some organic component. After heat treatment, the inorganic transformation occurred and it crystallized into pyrochlore structure. With increase of heat treatment temperature, the particles of mesoporous La2Zr2O7 become larger for the sintering of nanocrystalline La2Zr2O7. The surface area can retain at 92.7 m2/g after 600 °C, and decreased to 12.4 m2/g after 1200 °C for 3 h. This facile route provides a low-cost strategy for the preparation of mesoporous metal oxide with high surface area.
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      PubDate: 2016-07-25T06:00:43Z
       
  • Organic-inorganic hybrid microporous polymers based on
           Octaphenylcyclotetrasiloxane: Synthesis, carbonization and adsorption for
           CO2
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Zhihong Tian, Jiajia Huang, Zhonglu Zhang, Gonglei Shao, Ao Liu, Siguo Yuan
      Novel Organic-inorganic hybrid microporous polymers with excellent thermal stability, high surface areas (1041 m2 g−1) and controllable pore structures have been prepared via Scholl coupling and Friedel-Crafts reactions using Octaphenylcyclotetrasiloxane (OPCTS) as the building block, the pore structure of these OPCTS-based microporous polymers can be tuned by chosing crosslinking agent with different lengths of rigid connecting structure. Moreover, the as-prepared microporous polymers can serve as desirable carbon precursor to fabricate microporous carbons with uniform micromorphology, narrow pore size distribution, high microporosity (94%) and carbonization yield (58.8%). Both the hybrid microporous polymers and microporous carbons exhibit high CO2 adsorption capacities of 8.94 wt% (2.03 mmol g−1) and 14.78 wt% (3.36 mmol g−1) (273 K and 1 bar), respectively.
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      PubDate: 2016-07-25T06:00:43Z
       
  • Adsorption of NO in clinoptilolite-rich zeolitic mineral by concentration
           pulse chromatography method
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Güler Narin, Semra Ülkü
      The equilibrium and kinetic parameters for NO adsorption in a clinoptilolite-rich natural zeolitic material from Turkey were determined using the concentration pulse chromatography method. Under the experimental conditions (carrier gas velocities and adsorption temperatures) the micropore diffusion resistance was found to be the mass transfer controlling step. Matching the first moment of the response peaks to the mathematical model the Henry’s Law constants and heat of adsorption at zero loading were determined. The axial dispersion, external film, macropore and micropore diffusion coefficients, and activation energy for diffusion of NO in the micropores were calculated from the analysis of the second moments of the response peaks. For successive NO pulses without regeneration between the pulses, the retention times of the response peaks decreased and peak areas increased with the injection number indicating irreversible adsorption. The reversibly adsorbed NO could be desorbed by purging with an inert gas at the adsorption pressure and temperature. Temperature programmed desorption profile obtained by heating the NO saturated adsorbent to 400 °C under inert flow revealed presence of multiple irreversibly adsorbed species in NZ with different thermal stabilities. Desorption of these species was not achieved during the heating up to 400 °C which makes the natural zeolitic materıal suitable for NO storage rather than for cyclic adsorptive separation processes.
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      PubDate: 2016-07-25T06:00:43Z
       
  • Organosilanes functionalization of alumino-silica zeolites for water
           adsorption applications
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Lucio Bonaccorsi, Paolo Bruzzaniti, Luigi Calabrese, Edoardo Proverbio
      Standard zeolites 4A and 13X have been synthesized and modified by reaction with dimethoxydimethyl silane, propyltrimethoxy silane, octyltrimethoxy silane and octadecyltrimethoxy silane, respectively. The modified zeolites were analyzed by X-Ray diffractometry, FTIR spectrometry and water adsorption measurements. Results showed that silane molecules bonded to the external surface of zeolite particles with no chance of entering the zeolite porosity. Only “short-chain” silanes dimethoxydimethyl and propyltrimethoxy grafting demonstrated having an influence on the hydrophilic behavior of the modified zeolites. The main effect was a shift of the adsorption isotherms in the low partial pressure range towards a more hydrophobic trend, which represents an interesting result for adsorption application when low temperature regenerations are required.
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      PubDate: 2016-07-25T06:00:43Z
       
  • Porosity of SBA-15 after functionalization of the surface with
           aminosilanes
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): D. Majda, B.D. Napruszewska, M. Zimowska, W. Makowski
      Functionalization of the mesoporous silica walls by organic species results in formation of porous hybrid materials. Combination of organic and inorganic components leads to the materials whose properties differ considerably from those of their individual, isolated components, especially with respect to their surface chemistry, hydrophilicity/hydrophobicity and/or pore connectivity and size distribution. In this paper a detailed porosity characterization of SBA-15 silica before and after its surface functionalization with (R2O)3-Si-R1-NH2 molecules is reported. The results obtained from nitrogen sorption were compared to those derived from quasi-equilibrated thermodesorption of n-nonane and from water and n-heptane thermoporosimetry. A small decrease of the pores size and pore volume upon the modification was detected for all amine functionalities, the largest in the case of N-(2-aminoethyl)-3-(trimethoxysilyl) propylamine. Water thermoporosimetry was found to be the most sensitive method, allowing to quantify these differences.
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      PubDate: 2016-07-25T06:00:43Z
       
  • Single, binary, and mixture adsorption of nine organic contaminants onto a
           microporous and a microporous/mesoporous activated carbon cloth
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Sylvain Masson, Mickaël Gineys, Sandrine Delpeux-Ouldriane, Laurence Reinert, Sylvie Guittonneau, François Béguin, Laurent Duclaux
      The adsorption kinetics of nine contaminants (ibuprofen, carbamazepine, ofloxacin, bisphenol-A, diclofenac, mecoprop, pentachlorophenol, benzotriazol and caffeine) on a microporous and a microporous/mesoporous activated carbon cloth were studied in single, two-component and complete mixture at pH 7.5. Adsorption capacities at equilibrium were highest for the highly microporous carbon material, showing that pollutant adsorption mainly takes place in the micropores. This effect was more pronounced for small size adsorbates. Adsorption kinetics were increased for small size adsorbates thanks to their easy diffusion in the narrow porosity. Same behaviors were observed in the complex mixture containing the nine pollutants. Competition and sieving effects were observed in two-component mixtures, while considering two adsorbates having different molecular volumes, as for example caffeine and diclofenac. Moreover, the desorption of the co-adsorbates having the highest Gibbs energy value of adsorption determined from adsorption isotherms at 298 K (caffeine, mecoprop and benzotriazol) was observed for the kinetics of the complex mixture of the nine contaminants and of the two-component mixture. This desorption was provoked by the competition with the contaminants having lower Gibbs energy variation in single adsorption and thus strongly attracted at the adsorbent surface.
      Graphical abstract image

      PubDate: 2016-07-17T05:50:49Z
       
  • A review of the influence of source material’s oxide composition on
           the compressive strength of geopolymer concrete
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): M. Srinivasula Reddy, P. Dinakar, B. Hanumantha Rao
      Off late, geopolymer concrete has gained significant attention in the construction industry because of the benefits that it brings via, by-product waste utilization, reduction in greenhouse gas emission. Studies reveal that the chemical oxide composition of the raw material (viz., fly ash) strongly influences the mechanical behavior and durability properties of geopolymer concrete. However, not many studies have paid attention towards the influence of an oxide percentage in the raw material on the compressive strength of the geopolymer concrete. In this paper, an attempt has been made to study the compressive strength behavior against the percentage of oxides (viz., SiO2, Al2O3, Fe2O3, CaO etc.) present in the raw material which were employed in the production of geopolymer concrete. In this extensive data has been collected from various earlier research publications. Trends for 7 & 28 day compressive strengths against individual oxide component percentages were developed, and it was observed that the strength of geopolymer concrete differs greatly with the variation in percentage of the individual oxide component. Also, each oxide has shown distinct influence on the compressive strength of geopolymer concrete. Further, it has been noticed that the compressive strength of a sample has been predominantly influenced by the percentage of alumina-silicate oxides, and whereas oxides like CaO and Fe2O3 even though lesser in amount compared to alumina-silicate oxides have shown a distinctive effect on the strength built-up. Also, the oxide molar ratios influence on the compressive strengths has been analysed and it was noticed that compared to individual oxide composition its influence is not major on the compressive strength development. Therefore, knowing the typical range of the major oxides percentage required for achieving superior compressive strength will be beneficial in developing concrete mix proportion.
      Graphical abstract image

      PubDate: 2016-07-17T05:50:49Z
       
  • Innovative layer by layer and continuous growth methods for synthesis of
           ZIF-8 membrane on porous polymeric support using poly(ether-block-amide)
           as structure directing agent for gas separation
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): A. Jomekian, R.M. Behbahani, T. Mohammadi, A. Kargari
      Poly(ether-bock-amide) (Pebax grade 1657) was utilized as structure directing agent for fabrication of ZIF-8 membranes on polyphenylsulfone (PPSU) by layer-by-layer and continuous methods of growth. N2 adsorption, SEM, XRD, TGA and FTIR tests were applied to characterize the synthesized membranes. Polydimethylsiloxane (PDMS) was utilized to cover the possible surface defects of ZIF-8 membranes by dip coating method. The ideal performances of uncoated and coated synthesized ZIF-8 membranes were evaluated in separations of CO2/CH4, CO2/N2, H2/CH4 and H2/N2. The results showed that: 1- The coating of membranes by PDMS significantly enhanced the selectivity and decreased the permeance in almost all separation tests. 2- Higher numbers of cycles of solution changing in layer-by-layer method resulted in less permeable and more selective membranes. 3- Continuous growth method with PDMS coating lead to observation of maximum separation factors in many permeation tests: In permeances of 2.5 × 10−7 mol m−2 s−2 Pa−1 for H2 and 1.9 × 10−7 mol m−2 s−2 Pa−1 for CH4, exceptional ideal selectivities of 22.8, 20.8, 17.3 and 15.8 were obtained for H2/CH4, H2/N2, CO2/CH4 and CO2/N2, respectively.
      Graphical abstract image

      PubDate: 2016-07-17T05:50:49Z
       
  • One-step synthesis of nano-porous monolithic polyimide aerogel
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Jinyoung Kim, Jinuk Kwon, Seung-Ik Kim, Myeongsoo Kim, Daero Lee, Sangrae Lee, Gunhwi Kim, Juheon Lee, Haksoo Han
      A facile one-step method for synthesis of a porous monolithic polyimide aerogel was successfully developed. The specific thermal curing, slow desiccating process and swelling method were used in synthesizing monolithic polyimide aerogel without any additional chemical reaction to create a connected structure among the polyimide-based spherical aerogel microparticles. Using this method, the monolithic polyimide aerogel can be easily fabricated whilst using no additional chemicals for crosslinking. This type of polyimide aerogel was produced homogeneously by the polyimidization of pyromellitic dianhydride (PMDA) and 4,4′-oxydianiline (ODA). The synthesized porous monolithic polyimide aerogel has many good properties which could be used in various industries, as it maintained a high thermal decomposition temperature (10% weight decomposition temperature: Td10%) of approximately 577 °C and a glass transition temperature (Tg) of 432 °C, with bulk density of 490.7 kg/m3, porosity of approximately 45% and average pore size of 4 nm (by nitrogen adsorption test) of polymer and 157 nm (by mercury intrusion method) of space observed in FE-SEM image. Also, the monolithic polyimide aerogel had an excellent oil-adsorbing capacity of 150%, and the adsorbed oil could be separated easily using a simple drying process. The dried monolithic polyimide aerogel showed significant recoverability and reusability of adsorbed oil. In addition, the monolithic polyimide aerogel exhibited high mechanical resistance such that the structure can withstand a high pressure greater than 122.3 kPa, under which the monolithic polyimide aerogel (MPA) was compressed but did not break. This type of MPA shows excellent thermal, mechanical properties and great processability, and could be the new candidate for high performance materials in various industries, especially catalyst field.
      Graphical abstract image

      PubDate: 2016-07-17T05:50:49Z
       
  • Photoluminescent porous and layered lanthanide silicates: A review
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Bruno R. Figueiredo, Anabela A. Valente, Zhi Lin, Carlos Manuel Silva
      A large number of silicates containing transition metals and rare earth (in particular lanthanide) elements have been reported until recently. Generally, they exhibit a rich structural chemistry with interesting physical and chemical properties, and, in contrast to zeolites, which are built of [SiO4]4− and [AlO4]5− tetrahedrons, their frameworks embody metals in different coordination. In particular, materials containing rare earth and/or lanthanide elements may combine, in a single and stable solid, microporosity and tuneable optical properties. Such multi-functionality may be explored with interest, being a challenging approach to novel chemical and optical applications. This article aims to review rare earth and lanthanide silicates published to date, namely their relevant structure features and photoluminescent properties, being divided in two sections according to the major approaches used for their preparation, i.e. doping and embedding. The parent materials hosting the rare earth or lanthanide elements, the type and number of such emitters, and the disorder and dimensionality of the solids are some of the addressed topics. Furthermore, this review is also intended to highlight the great challenges that optical centres design offers in the field of material science. Some potential applications are also debated, such as wastewater remediation, nuclear medicine, imaging, and sensors. Notwithstanding the relevance that photoluminescent porous and layered lanthanide silicates may achieve in wastewater treatment, as a result of their stability and high selectivity combined with capacity, their sensing ability towards a specific ion or molecule will be for sure of capital importance in the near future.
      Graphical abstract image

      PubDate: 2016-07-17T05:50:49Z
       
  • The promoting effects of alkali metal oxide in side-chain alkylation of
           toluene with methanol over basic zeolite X
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): He Han, Min Liu, Xiaowa Nie, Fanshu Ding, Yiren Wang, Junjie Li, Xinwen Guo, Chunshan Song
      The side-chain alkylation of toluene with methanol was investigated on a series of catalysts which were prepared by ion-exchange or subsequent impregnation of zeolie X with potassium hydroxide or cesium hydroxide aqueous solution. The catalysts were characterized by X-ray diffraction, scanning electron microscopy, X-ray fluorescence, Ar physical adsorption-desorption, NH3 temperature-programmed desorption (TPD), CO2-TPD, pyridine adsorption Fourier-transform infrared (FT-IR) spectroscopy, FT-IR spectroscopy in OH stretch region, thermogravimetric/differential thermal analysis, ultraviolet-Raman spectroscopy, and X-ray photoelectron spectroscopy. It was found that alkali metal oxide played extremely important roles in the modification of catalysts and in the catalytic reaction pathway. Strong basic sites were formed by modification of basic zeolite X with alkali metal oxide. These basic sites promoted the dehydrogenation of methanol to formaldehyde which was recognized as the true alkylating agent in side-chain alkylation. Consequently, side-chain alkylation of toluene with formaldehyde was enhanced. As toluene was mainly adsorbed and activated on alkali metal cations bonded on the zeolite framework, the synergistic effects between alkali metal oxide and alkali metal cations were proposed. One of the possible reaction path ways for side-chain alkylation of toluene with methanol over basic zeolite was described. Alkali metal ion-exchanged zeolite X modified with alkali metal oxide demonstrated relatively high side-chain alkylation activity. However, the improvement of styrene selectivity faced with great challenges.
      Graphical abstract image

      PubDate: 2016-07-17T05:50:49Z
       
  • Antimicrobial behavior of ion-exchanged zeolite X containing fragrance
    • Abstract: Publication date: 1 November 2016
      Source:Microporous and Mesoporous Materials, Volume 234
      Author(s): Rumeysa Tekin, Nurcan Bac
      Microporous zeolites are aluminosilicates composed of silicon, aluminum, and oxygen in a framework with cations. The cation contents can be exchanged with metal ions in order to add antimicrobial (antibacterial, anticandidal, and antifungal) properties. Zeolites has also recently been acquainted with fragrance applications to tailor products with controlled release properties. Here, a new application of ion exchanged zeolite X combined with adsorption properties is presented. In this study, zeolite X crystals were ion-exchanged with Zn2+ and Cu2+ ions and encapsulation of a fragrance molecule, triplal, was studied using ion-exchanged zeolite X as a fragrance carrier. The antimicrobial behavior of ion-exchanged zeolite X before and after encapsulation were investigated by disc diffusion method. Zn2+ and Cu2+ loaded zeolite samples showed excellent antimicrobial activities against three bacteria Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa, a yeast Candida albicans and a fungus Aspergillus niger. Ion-exchanged zeolite X samples containing triplal sustained antimicrobial activities after the encapsulation process.
      Graphical abstract image

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

      PubDate: 2016-07-17T05:50:49Z
       
 
 
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