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Journal Cover Microporous and Mesoporous Materials
  [SJR: 1.243]   [H-I: 116]   [10 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1387-1811
   Published by Elsevier Homepage  [3049 journals]
  • Microfibrous-structured hollow-ZSM-5/SS-fiber catalyst with mesoporosity
           development dependent lifetime improvement for MTP reaction
    • Authors: Jia Ding; Yingshuai Jia; Pengjing Chen; Guofeng Zhao; Ye Liu; Yong Lu
      Pages: 1 - 8
      Abstract: Publication date: 1 May 2018
      Source:Microporous and Mesoporous Materials, Volume 261
      Author(s): Jia Ding, Yingshuai Jia, Pengjing Chen, Guofeng Zhao, Ye Liu, Yong Lu
      A promising thin-felt stainless-steel-fiber (SS-fiber) structured hollow-ZSM-5/SS-fiber catalyst is developed through alkali leaching of the full-silica core from the silicalite-1@ZSM-5/SS-fiber. A silicalite-1 seeded dry-gel/SS-fiber is obtained by dip-coating technique and is then transformed into the silicalite-1@ZSM-5/SS-fiber (overall SiO2/Al2O3 molar ratio of 93) via seed-assisted dry gel conversion method. Such catalyst shows marked enhancement of mesoporosity development because of the abundant hollow structures left behind after the silicalite-1 core removal by alkali treatment in a mild Na2CO3 media. The effect of alkali-treated time length on catalyst structure, textural and acidic properties as well as methanol-to-propylene (MTP) performance is systematically investigated. As-obtained catalyst, with well-maintained Brönsted acid sites after alkali treatment, shows hollow-structure-dependent stability improvement in the MTP and n-hexane cracking processes due to markedly enhanced diffusion.
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      PubDate: 2017-11-09T21:35:57Z
      DOI: 10.1016/j.micromeso.2017.10.052
      Issue No: Vol. 261 (2017)
       
  • Hydrogen incorporation by plasma treatment gives mesoporous black TiO2
           thin films with visible photoelectrochemical water oxidation activity
    • Authors: Syed Z. Islam; Allen Reed; Suraj Nagpure; Namal Wanninayake; James F. Browning; Joseph Strzalka; Doo Young Kim; Stephen E. Rankin
      Pages: 35 - 43
      Abstract: Publication date: 1 May 2018
      Source:Microporous and Mesoporous Materials, Volume 261
      Author(s): Syed Z. Islam, Allen Reed, Suraj Nagpure, Namal Wanninayake, James F. Browning, Joseph Strzalka, Doo Young Kim, Stephen E. Rankin
      Neutron reflectometry (NR) is used to investigate the role of hydrogen in the visible light absorption and enhanced photoactivity for water oxidation of mesoporous black titania thin films. The cubic mesoporous frameworks of TiO2 thin films are prepared by a surfactant-templated sol-gel method and subsequently treated with hydrogen plasma, an approach hypothesized to capitalize on the high degree of disorder in the material and the high energy of the plasma species to achieve efficient hydrogen doping. UV-vis absorbance spectra indicate broad-spectrum visible light absorption in H2 plasma-treated black TiO2 films, and XPS indicates the generation of reduced Ti3+ in the treated films. The presence of hydrogen in black mesoporous titania (H-TiO2) films is confirmed by the scattering length density (SLD) profiles obtained from neutron reflectometry measurements. The H-TiO2 shows ca. 28 times and 8 times higher photocurrent for photoelectrochemical water oxidation compared to undoped TiO2 films under UV (365 nm) and blue (455 nm) LED irradiation, respectively. These findings provide direct evidence that the dramatic change in visible light absorbance of H-treated black TiO2 is accompanied by significant hydrogen uptake and not just Ti3+ generation or surface disordering.
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      PubDate: 2017-11-09T21:35:57Z
      DOI: 10.1016/j.micromeso.2017.10.036
      Issue No: Vol. 261 (2017)
       
  • One-pot synthesis of acidic and basic bifunctional catalysts to promote
           the conversion of ethanol to 1-butanol
    • Authors: Xue Ni Li; Song Song Peng; Li Na Feng; Shao Qing Lu; Ling Juan Ma; Ming Bo Yue
      Pages: 44 - 50
      Abstract: Publication date: 1 May 2018
      Source:Microporous and Mesoporous Materials, Volume 261
      Author(s): Xue Ni Li, Song Song Peng, Li Na Feng, Shao Qing Lu, Ling Juan Ma, Ming Bo Yue
      The conversion of ethanol to 1-butanol could allow the effective use of bioethanol as a renewable fuel, but requires a catalyst with both strongly acidic and basic sites. In the present work, a series of basic/acidic bifunctional catalysts was prepared by the calcination of KNO3 loaded onto granular coconut shell carbon (CSC) at varying temperatures. An extensive characterization using powder X-ray diffraction, scanning electron microscopy, surface area analysis, and NH3- and CO2-temperature programmed desorption was performed in order to understand structure−activity trends. The CSC structure was found to be well preserved following calcination and the resulting catalysts exhibited both basic and acidic properties. The decomposition of KNO3 played an important role in the formation of these sites, and it was determined that moderately basic/acidic sites were the most helpful in promoting the aldol coupling of ethanol. These new materials show significant potential for application to the ethanol-to-1-butanol reaction, with the highest-performing specimen (made with 10 wt% KNO3 and calcined at 500 °C) exhibiting 60% C4 products selectivity at 50% ethanol conversion.
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      PubDate: 2017-11-09T21:35:57Z
      DOI: 10.1016/j.micromeso.2017.11.004
      Issue No: Vol. 261 (2017)
       
  • Hierarchical zeolite ZSM-58 as shape selective catalyst for
           methanol-to-olefins reaction
    • Authors: Carolin Selzer; Tim Biemelt; Anja Werner; Stefan Kaskel
      Pages: 51 - 57
      Abstract: Publication date: 1 May 2018
      Source:Microporous and Mesoporous Materials, Volume 261
      Author(s): Carolin Selzer, Tim Biemelt, Anja Werner, Stefan Kaskel
      A hierarchical zeolite ZSM-58 architecture, with zeolitic DDR topology, was synthesized via postsynthetic desilication using sodium hydroxide solutions with varying concentration in presence of tetraethylammonium ions acting as pore growth moderator. Resulting ZSM-58 materials were analyzed by X-ray diffraction, argon physisorption, scanning electron microscopy and temperature-programmed desorption of ammonia. By varying the base concentration, intracrystalline mesopores with a volume up to 0.50 cm3 g−1 were introduced. Due to enhanced adsorption/desorption kinetics, all desilicated ZSM-58 samples exhibited longer catalytic lifetime and higher product yields in the methanol-to-olefins (MTO) reaction compared to purely microporous ZSM-58. All catalyst materials achieved a remarkably narrow product spectrum with yields around 80% for the C2-/C3-fraction and absence of products larger than C5.
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      PubDate: 2017-11-09T21:35:57Z
      DOI: 10.1016/j.micromeso.2017.11.005
      Issue No: Vol. 261 (2017)
       
  • Fabrication of high-performance silicalite-1 membrane by a novel seeding
           method using zeolite-dispersed polymer film
    • Authors: Kyohei Ueno; Yui Horiguchi; Hideyuki Negishi; Manabu Miyamoto; Sigeyuki Uemiya; Akiyoshi Takeno; Yoshiharu Sawada; Yasunori Oumi
      Pages: 58 - 62
      Abstract: Publication date: 1 May 2018
      Source:Microporous and Mesoporous Materials, Volume 261
      Author(s): Kyohei Ueno, Yui Horiguchi, Hideyuki Negishi, Manabu Miyamoto, Sigeyuki Uemiya, Akiyoshi Takeno, Yoshiharu Sawada, Yasunori Oumi
      A highly reproducible silicalite-1 membrane with high pervaporation performance was successfully prepared on a tubular silica support by a novel seeding method using a zeolite-dispersed polymer film. The proposed seeding method (film seeding) allowed for the formation of a uniform and continuous zeolite seed layer with high reproducibility on the support surface in a single seeding step, resulting in a membrane with high separation performance. The synthesized membrane had a continuous and dense zeolite layer with a thickness of approximately 12 μm and exhibited an ethanol/water separation factor of 120 and flux of 3.16 kg m−2 h−1 for 10 wt% ethanol/water mixtures at 323 K by pervaporation. This novel seeding method should lead to the development of new processes for synthesizing zeolite membranes that show both high performance and reproducibility. Moreover, given the simplicity and effectiveness of the method, it has immense potential for use in the commercial production of various types of zeolite membranes.
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      PubDate: 2017-11-09T21:35:57Z
      DOI: 10.1016/j.micromeso.2017.11.001
      Issue No: Vol. 261 (2017)
       
  • Sonosynthesis of VOx/MCM-41 nanocatalyst enhanced by various metal oxides
           (Mg, AL, Zr) for CO2-oxidative dehydrogenation of ethane to ethylene
    • Authors: Parisa Taghavinezhad; Mohammad Haghighi; Reza Alizadeh
      Pages: 63 - 78
      Abstract: Publication date: 1 May 2018
      Source:Microporous and Mesoporous Materials, Volume 261
      Author(s): Parisa Taghavinezhad, Mohammad Haghighi, Reza Alizadeh
      To develop an efficient V-based catalyst for oxidative dehydrogenation of ethane by CO2, MCM-41was modified with various metal oxides (Mg, Al, Zr) and then, impregnated with aqueous solution of NH4VO3 and then tested in dehydrogenation of ethane with CO2 at different temperatures. The obtained catalysts have been characterized by powder X-ray diffraction, BET, FESEM, FTIR, EDX, TPD-NH3 and UV-Vis. DRS analysis. The results show that introduction of various metal oxides alter structural properties of fabricated V/MCM-41catalyst, such as crystallography, vanadium oxo-species dispersion, particle size distribution and acid-base properties which can improve catalytic performance of synthesized nanocatalyst. Among the studied catalysts, the MCM-41 family catalyst containing MgO and ZrO2 showed the best performance and effectively dehydrogenated ethane to ethylene in the presence of CO2 at 700 °C giving 43% ethylene yield. This catalyst remained stable even after 10 h on stream.
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      PubDate: 2017-11-09T21:35:57Z
      DOI: 10.1016/j.micromeso.2017.10.057
      Issue No: Vol. 261 (2017)
       
  • Design of ZIF-8/ion copolymer hierarchically porous material: Coordination
           effect on the adsorption and diffusion for carbon dioxide
    • Authors: Qirui Guo; Chong Chen; Lijin Zhou; Xue Li; Zhong Li; Dashui Yuan; Jing Ding; Hui Wan; Guofeng Guan
      Pages: 79 - 87
      Abstract: Publication date: 1 May 2018
      Source:Microporous and Mesoporous Materials, Volume 261
      Author(s): Qirui Guo, Chong Chen, Lijin Zhou, Xue Li, Zhong Li, Dashui Yuan, Jing Ding, Hui Wan, Guofeng Guan
      The novel CO2 adsorbent (ZPMAC) was constructed by a facile in-situ growth of ZIF-8 onto the surface of a mesoporous amino-functionalized ion copolymer (PMAC). The existence of coordination effect between Zn2+ from ZIF-8 and nitrogen atom from the amino-alkyl chain in PMAC changed the pore structure of substrate for enhancing the amount of CO2 capture and accelerated the rate of CO2 adsorption. The ion copolymer PMAC, pristine ZIF-8 and hierarchically porous hybrid material ZPMAC were characterized by SEM, TEM, TGA, N2 adsorption-desorption, FT-IR, XRD, UV, and XPS techniques. It was observed that ZIF-8 loaded on the surface of PMAC uniformly and tightly. In the growth process of ZIF-8 nanoparticles, zinc ions were firstly coordinated with nitrogen atoms of the amino-alkyl chain in PMAC sample, and subsequently reacted with 2-methylimizadole to generate ZIF-8 nanoparticles. Obviously, the surface areas of ZPMAC increased and smaller peak value of micropore distribution was generated by the strong coordination interaction between ZIF-8 and PMAC after ZIF-8 modified. Meanwhile, the appearance of hierarchically porous structure was conducive to the transportation and adsorption of CO2 molecules, thus enhancing the amount of CO2 capture and the rate of adsorption effectively. This study was intended to design a new kind of hybrid materials by the means of in-situ growth of MOF materials onto the IL-type polymers and further study the influences of the structure and properties of ionic-type hybrid materials on the absorption capacity to meet the requirements of various applications.
      Graphical abstract image

      PubDate: 2017-11-09T21:35:57Z
      DOI: 10.1016/j.micromeso.2017.11.007
      Issue No: Vol. 261 (2017)
       
  • Efficient N-doping of hollow core-mesoporous shelled carbon spheres via
           hydrothermal treatment in ammonia solution for the electrocatalytic oxygen
           reduction reaction
    • Authors: Tingsheng Zhou; Ruguang Ma; Yao Zhou; Ruohao Xing; Qian Liu; Yufang Zhu; Jiacheng Wang
      Pages: 88 - 97
      Abstract: Publication date: 1 May 2018
      Source:Microporous and Mesoporous Materials, Volume 261
      Author(s): Tingsheng Zhou, Ruguang Ma, Yao Zhou, Ruohao Xing, Qian Liu, Yufang Zhu, Jiacheng Wang
      Nitrogen-doped hollow core-mesoporous shelled carbon spheres (NHMCSs) are successfully synthesized via a simple, scalable hydrothermal treatment of hollow mesoporous carbon spheres (HMCSs) with ammonia water as the nitrogen source. This strategy not only efficiently introduces nitrogen atoms into the carbon framework, but also causes the fracture of some spheres and increases the shell thickness of hollow spheres. The subsequent pyrolysis at 900 °C in Ar results in the transformation of pyrrolic-N to graphitic-N. The resulting NHMCS-900 has a high BET specific surface area (648 m2 g−1), large pore volume (1.06 cm3 g−1), hierarchical mesoporosity (2–8, 43.9 nm), uniform shells and large hollow cores. The electrochemical experiments indicate that NHMCS-900 as a metal-free electrocatalyst possesses the improved ORR activity with a close four-electron reaction pathway (∼3.88) and a peroxide yield lower than 10% over a wide potential range in alkaline solution. Contrary to commercial Pt/C, NHMCS-900 is unaffected by the methanol crossover effect and exhibits excellent long-term durability with 97.0% of the initial current density after 5.56 h of continuous operation. The excellent activity of NHMCS-900 is mainly attributed to the high relative content of pyridinic-N and graphitic-N. Besides, the superior activity is also ascribed to its unique structural properties, promoting fast and efficient mass transfer and providing inner and outer surfaces with N-relative active sites for ORR.
      Graphical abstract image

      PubDate: 2017-11-09T21:35:57Z
      DOI: 10.1016/j.micromeso.2017.10.050
      Issue No: Vol. 261 (2017)
       
  • Oxidative removal of sulfa antibiotics by introduction of activated carbon
           fiber to enhance the catalytic activity of iron phthalocyanine
    • Authors: Ying Wang; Yuan Fang; Wangyang Lu; Nan Li; Wenxing Chen
      Pages: 98 - 104
      Abstract: Publication date: 1 May 2018
      Source:Microporous and Mesoporous Materials, Volume 261
      Author(s): Ying Wang, Yuan Fang, Wangyang Lu, Nan Li, Wenxing Chen
      Supported metallophthalocyanine catalysts were synthesized by immobilizing covalently amino-containing iron trinitro phthalocyanine (FeMATNPc) on activated carbon fibers (ACF) by deamination to produce ACF-FeTNPc. The introduction of ACF enhanced the decomposition of sulfamethoxazole by FeMATNPc significantly with an obvious improvement in pH tolerance and stability. The oxidative removal of sulfamethoxazole(SMX) in the ACFs-FeTNPc/H2O2 system, based on phase-transfer catalytic oxidation, was investigated in aqueous solution by ultra-performance liquid chromatography. Repetitive tests showed that ACF-FeTNPc could maintain a high adsorption capacity and degradation activity over several cycles. The resulting hybrid structure was confirmed and characterized by X-ray photoelectron and ultraviolet–visible spectroscopy. ACF are rich in free electrons, and the π-conjugated macrocyclic structure of FeMATNPc may present convenient channels for the transfer of free electrons from the ACF, and promote the generation of hydroxyl radicals and high-valence iron species. Electron paramagnetic resonance spin-trap experiments and inhibition and probe studies indicated that free radicals and high-valence iron species reacted in our system.
      Graphical abstract image

      PubDate: 2017-11-09T21:35:57Z
      DOI: 10.1016/j.micromeso.2017.10.055
      Issue No: Vol. 261 (2017)
       
  • Effect of graphene oxide on the adsorption properties of ordered
           mesoporous carbons toward H2, C6H6, CH4 and CO2
    • Authors: Barbara Szczęśniak; Jerzy Choma; Mietek Jaroniec
      Pages: 105 - 110
      Abstract: Publication date: 1 May 2018
      Source:Microporous and Mesoporous Materials, Volume 261
      Author(s): Barbara Szczęśniak, Jerzy Choma, Mietek Jaroniec
      Graphene oxide/ordered mesoporous carbon (GO/OMC) nanostructures with narrow mesopore size distribution were obtained via soft-templating synthesis followed by KOH activation. Microporosity and mesoporosity of these composite nanostructures were additionally controlled by adjusting the amount of added GO and by post-synthesis KOH activation. Incorporation of GO into OMC structure resulted in improving adsorption uptakes of benzene and hydrogen, which reached 9.6 mmol/g (at 20 °C and pressure close to the saturation vapor pressure) and 11.7 mmol/g (2.3 wt% H2 at −196 °C and 760 mm Hg), respectively. At the same conditions bare activated OMC adsorbed 8.1 mmol/g and 10.8 mmol/g of benzene and hydrogen, respectively. Also, these adsorbents showed high uptakes of CH4 (2.1 mmol/g at 20 °C and 760 mm Hg) and CO2 (6.0 mmol/g at 0 °C and 760 mm Hg). The GO/OMC composite nanostructures were characterized by nitrogen adsorption, scanning electron microscopy, Raman spectroscopy and thermogravimetry. To the best of our knowledge, this work represents the first comparative study of adsorption properties of the GO/OMC composite nanostructures toward various gases.
      Graphical abstract image

      PubDate: 2017-11-09T21:35:57Z
      DOI: 10.1016/j.micromeso.2017.10.054
      Issue No: Vol. 261 (2017)
       
  • Simultaneous effects of water, TEAOH and morpholine on SAPO-34 synthesis
           and its performance in MTO process
    • Authors: Hussein Bahrami; Jafar Towfighi Darian; Mehdi Sedighi
      Pages: 111 - 118
      Abstract: Publication date: 1 May 2018
      Source:Microporous and Mesoporous Materials, Volume 261
      Author(s): Hussein Bahrami, Jafar Towfighi Darian, Mehdi Sedighi
      Simultaneous effects of water, tetraethyl ammonium hydroxide (TEAOH) and morpholine in the initial gel are investigated under hydrothermal synthesis of the SAPO-34 molecular sieve. Physicochemical properties of synthesized catalysts were characterized by techniques of XRD, SEM, BET, ICP, FTIR and NH3-TPD. A TEAOH increment causes a reduction of crystallinity and particle size, and an increase of strong acid site. Increasing water at a high TEAOH intensifies the concentration and the strength of the weak and the strong acid site. Controlling the properties of the synthesis catalysts improves the light olefins yield and the lifetime. The best catalyst was synthesized with 1.71 mol of TEAOH, 0.29 mol of morpholine and 85.61 mol of water, which it has a propylene of 15.46 (g/100gMeOH), an ethylene of 15.07 (g/100gMeOH), a total olefins yield of 32.32 (g/100gMeOH), and a lifetime of 21.12 (gMeOH/gCat). This is due to both the optimum intracrystalline diffusion path length and the optimum strong acidity.
      Graphical abstract image

      PubDate: 2017-11-09T21:35:57Z
      DOI: 10.1016/j.micromeso.2017.11.011
      Issue No: Vol. 261 (2017)
       
  • Self-templated synthesis of interconnected porous carbon nanosheets with
           controllable pore size: Mechanism and electrochemical capacitor
           application
    • Authors: Jiyoung Lee; Yeong A. Lee; Chung-Yul Yoo; Jung Joon Yoo; Raekeun Gwak; Woo Kyung Cho; Bongsoo Kim; Hana Yoon
      Pages: 119 - 125
      Abstract: Publication date: 1 May 2018
      Source:Microporous and Mesoporous Materials, Volume 261
      Author(s): Jiyoung Lee, Yeong A. Lee, Chung-Yul Yoo, Jung Joon Yoo, Raekeun Gwak, Woo Kyung Cho, Bongsoo Kim, Hana Yoon
      Interconnected porous carbon nanosheets (IPCNs) are promising candidates for use as the electrode materials of electrochemical capacitors, as adsorbents, and as catalytic supports because of their high surface area, efficient ion transport, and three-dimensional (3D) structure. Herein, IPCNs with easily adjustable pore-size distributions, ranging from micro- to mesoporous, are synthesized by the carbonization of alkali metal citrates in a single-step self-templating process. Microporous, mesoporous, and hierarchical micro/mesoporous IPCNs are produced by empolying potassium citrate, sodium citrate, and their mixtures, respectively. Particularly, the hierarchical micro/mesoporous IPCNs derived from the mixture of potassium and sodium citrates in a weight ratio of 8:2 exhibit good electrochemical performance, including high specific capacitance (∼200 F/g at 5 mV/s) and excellent rate capability and cyclability. In addition, the structural changes in the carbon materials produced using pyrolysis are thoroughly studied, and the mechanism of IPCN formation is elucidated. The study on the synthetic mechanism of IPCNs provides an important guidance for designing superb porous carbon materials possessing desirable pore structures and particle morphologies for a variety of applications.
      Graphical abstract image

      PubDate: 2017-11-17T05:43:04Z
      DOI: 10.1016/j.micromeso.2017.10.047
      Issue No: Vol. 261 (2017)
       
  • Biomimetic hierarchical walnut kernel-like and erythrocyte-like mesoporous
           silica nanomaterials: Controllable synthesis and versatile applications
    • Authors: Nanjing Hao; Yuan Nie; John X.J. Zhang
      Pages: 144 - 149
      Abstract: Publication date: 1 May 2018
      Source:Microporous and Mesoporous Materials, Volume 261
      Author(s): Nanjing Hao, Yuan Nie, John X.J. Zhang
      We developed a facile and controllable strategy to fabricate biomimetic walnut kernel-like mesoporous silica nanomaterial (WMSN) and erythrocyte-like mesoporous silica nanomaterial (EMSN). The former possesses unique multi-shell hollow structure and surface wrinkles while the latter has special multi-stack structure and bowl-shaped depression. These hierarchical materials with distinct structures can be finely tuned by changing the molar ratios of two surfactants, cetyltrimethylammonium bromide and 11-mercaptoundecanoic acid. The mechanism of structural formation through intermolecular interactions was revealed and validated experimentally. The promising potential applications of WMSN and EMSN in adsorption, cellular imaging, drug delivery, and cancer theranostics were further identified.
      Graphical abstract image

      PubDate: 2017-11-17T05:43:04Z
      DOI: 10.1016/j.micromeso.2017.11.003
      Issue No: Vol. 261 (2017)
       
  • Bio-inspired manganese mesoporous silica hybrid material as a water
           compatible antioxidant
    • Authors: Beltzane Garcia-Cirera; Montserrat Corbella; Laurent Bonneviot; Belén Albela
      Pages: 150 - 157
      Abstract: Publication date: 1 May 2018
      Source:Microporous and Mesoporous Materials, Volume 261
      Author(s): Beltzane Garcia-Cirera, Montserrat Corbella, Laurent Bonneviot, Belén Albela
      MnIII dinuclear compounds mimicking the active site of the antioxidant Mn-catalase are often instable in water. The water compatibility necessary for nanomedicine applications is obtained here by fixation inside a functionalized mesoporous silica. Two functions, pyridine moieties and tetramethylammonium ions, are considered for the matrix functionalization: the former to fix the manganese complex and the second to maintain a suitable pH for an optimal catalase activity. These functions are homogeneously distributed in the pore by sequential surface reactions using a molecular surface patterning technique. Ultra-fast microwave heating for the synthesis of the silica matrix and a minimization of toxic chemicals for its modification are used for a greener preparation. The manganese complex −very active in acetonitrile and inactive in water− becomes very active in water when it is incorporated in the host silica matrix. The hybrid material can be advantageously recycled with no significant metal leaching. Moreover, it shows very promising activity in MOPS, a buffer used by biologists.
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      PubDate: 2017-11-17T05:43:04Z
      DOI: 10.1016/j.micromeso.2017.10.034
      Issue No: Vol. 261 (2017)
       
  • Remarkable epoxidation activity of neat and carbonized niobium silicates
           prepared by evaporation-induced self-assembly
    • Authors: Anand Ramanathan; Hongda Zhu; Rajamanickam Maheswari; Bala Subramaniam
      Pages: 158 - 163
      Abstract: Publication date: 1 May 2018
      Source:Microporous and Mesoporous Materials, Volume 261
      Author(s): Anand Ramanathan, Hongda Zhu, Rajamanickam Maheswari, Bala Subramaniam
      A series of mesoporous Nb-silicates with varying Nb loading from 2.2 to 22.0 wt% were synthesized by the Evaporation-Induced Self-Assembly (EISA) method using Pluronic P123 as mesopore forming agent. High dispersion of NbOx species was achieved up to a Nb loading of ∼22 wt% without any formation of bulk crystalline Nb2O5. Small angle X-ray scattering, TEM and N2 physisorption confirm mesoporosity in these materials with short-range ordering. The BET surface area and pore volume range from 779 to 978 m2/g and 0.76–1.21 cm3/g, decreasing at higher Nb loadings. Isolated NbO4 and oligomeric NbOx species were evident from diffuse reflectance UV-Vis spectra. For the epoxidation of cyclohexene with H2O2, the Nb-EISA catalysts generally perform better in terms of activity, epoxidation selectivity and H2O2 utilization compared to other mesoporous niobium silicates. Further, a significant improvement in the epoxide selectivity was achieved with Nb-EISA samples calcined in N2 during synthesis such that a thin C layer is left behind. The C layer may induce pore hydrophobicity that prevents the ring-opening reaction of the primary epoxide product.
      Graphical abstract image

      PubDate: 2017-11-17T05:43:04Z
      DOI: 10.1016/j.micromeso.2017.10.049
      Issue No: Vol. 261 (2017)
       
  • In situ transformation of geopolymer gels to self-supporting NaX zeolite
           monoliths with excellent compressive strength
    • Authors: Hongquan Wang; Chunjie Yan; Dan Li; Feng Zhou; Yi Liu; Chunyu Zhou; Sridhar Komarneni
      Pages: 164 - 169
      Abstract: Publication date: 1 May 2018
      Source:Microporous and Mesoporous Materials, Volume 261
      Author(s): Hongquan Wang, Chunjie Yan, Dan Li, Feng Zhou, Yi Liu, Chunyu Zhou, Sridhar Komarneni
      Geopolymers are a new class of green high-strength aluminosilicate materials, which generally maintain an amorphous structure due to the limitations related to their chemical compositions and reaction conditions but possess the ability to form molecular sieves. In this work, the in-situ transformation of geopolymers into self-supporting NaX zeolite monoliths of relatively large sizes was examined under hydrothermal conditions and various parameters of the synthesis process were optimized. The obtained results indicated that the optimal transformation conditions for geopolymers with a Si/Al ratio of 4.0 are as follows: precursors composed of metakaolin and modified industrial sodium silicate with a Na2O/SiO2 molar ratio of 1.0, H2O/Na2O molar ratio of 70, hydrothermal synthesis time of 18 h and a temperature of 90 °C. According to the obtained X-ray diffraction (XRD) data, the synthesized NaX Monoliths exhibited characteristic reflections consistent with those of standard NaX zeolites and possessed high degrees of crystallinity, while scanning electron microscopy revealed that the produced molecular sieves exhibited well-defined morphology. In addition, the zeolitic monoliths exhibited excellent compressive strength for potential practical applications.
      Graphical abstract image

      PubDate: 2017-11-17T05:43:04Z
      DOI: 10.1016/j.micromeso.2017.11.015
      Issue No: Vol. 261 (2017)
       
  • Synthesis, dynamic characterization, and modeling studies of an AM-3
           membrane for light gases separation
    • Authors: Simão P. Cardoso; Zhi Lin; Inês Portugal; Alírio E. Rodrigues; Carlos M. Silva
      Pages: 170 - 180
      Abstract: Publication date: 1 May 2018
      Source:Microporous and Mesoporous Materials, Volume 261
      Author(s): Simão P. Cardoso, Zhi Lin, Inês Portugal, Alírio E. Rodrigues, Carlos M. Silva
      A new AM-3 membrane was prepared on a stainless-steel support for potential application in the separation of light gases, particularly hydrogen containing mixtures. It was dynamically characterized by permeation assays using H2, He, N2, CO2, and O2 at fixed and programmed temperatures (between 304 and 394 K), and transmembrane pressure drops from 0.5 to 1.5 bar. The experimental results disclosed high selectivity of the AM-3 membrane towards hydrogen. In terms of transport mechanisms, they evidenced an activated behavior typical of surface diffusion, and a small contribution of macro-defects. The existence of intercrystalline micro-defects was revealed by the permeation of N2, O2, and CO2, whose kinetic diameters are larger than the pore diameter of AM-3. Gas permeation was accurately modeled based on the Maxwell-Stefan approach for surface diffusion in micropores, with additional terms for Knudsen and viscous fluxes through meso- and macro-defects. The global deviation achieved for the five gases was only 3.42%. The calculated results demonstrated that: viscous flow prevailed at low temperature (304 K), surface diffusion dominated when temperature increased, Knudsen transport was residual, the flux through defects predominated at 304 K (53.8–73.5% of total flux) but fell below 15% for temperatures above 370 K, and the influence of the support was negligible.
      Graphical abstract image

      PubDate: 2017-11-17T05:43:04Z
      DOI: 10.1016/j.micromeso.2017.11.008
      Issue No: Vol. 261 (2017)
       
  • Molecular simulation study of wet flue gas adsorption on zeolite 13X
    • Authors: Mark J. Purdue; Zhiwei Qiao
      Pages: 181 - 197
      Abstract: Publication date: 1 May 2018
      Source:Microporous and Mesoporous Materials, Volume 261
      Author(s): Mark J. Purdue, Zhiwei Qiao
      Understanding the effect of moisture in an adsorbent that is selective to CO2 over N2 is central to the design and development of adsorption technology for CO2 capture and concentration from power plant flue gas. Molecular simulations of wet flue gas adsorption on Zeolite 13X were here performed in the grand canonical (μVT) ensemble using the Monte Carlo technique in atomistic detail. The generated multicomponent isotherm data spanned the complete gas mixture composition range for adsorbing species CO2, N2 and H2O from 25 °C to 75 °C at 1atm. The adsorption simulations consisted of faujasite zeolite crystal structures with a fixed Si/Al ratio of 1.31, Na+ cation mobility and beta sodalite cage blocking of CO2 and N2 using 4 Å radius virtual blocking spheres. Simulated equilibrium isotherm data demonstrated that the presence of even small amounts of water vapor in the gas mixture has a significant impact on the adsorbate loadings for the remaining gas components in Zeolite 13X. Structural analysis with radial distribution functions revealed a shift in CO2 adsorption away from the framework structure towards α-cavity pore centres and exclusion from sites adjacent to Na+(II) when H2O is present in the gas mixture. A degree of competitive adsorption of CO2 at Na+(III) sites persists at up to 15% relative humidity (RH) at 298 K (0.5 mol% H2O) with significant lateral adorbate-H2O interactions but exclusion beyond that threshold. Lower CO2 loadings were associated with the growth of hydrogen bonded clusters with major changes complete by RH = 20% at 298 K.
      Graphical abstract image

      PubDate: 2017-11-17T05:43:04Z
      DOI: 10.1016/j.micromeso.2017.10.059
      Issue No: Vol. 261 (2017)
       
  • Development of citric anhydride anchored mesoporous MOF through post
           synthesis modification to sequester potentially toxic lead (II) from water
           
    • Authors: Ayoub Abdullah Alqadami; Moonis Ali Khan; Masoom Raza Siddiqui; Zeid Abdullah Alothman
      Pages: 198 - 206
      Abstract: Publication date: 1 May 2018
      Source:Microporous and Mesoporous Materials, Volume 261
      Author(s): Ayoub Abdullah Alqadami, Moonis Ali Khan, Masoom Raza Siddiqui, Zeid Abdullah Alothman
      Here in, a post synthesis modification (PSM) approach was adopted for anchoring citric anhydride (CA) with NH2-MIL-53(Al) through covalent linkage between amino (–NH2) group of NH2-MIL-53(Al) and carboxylic group of CA to develop mesoporous amide citric anhydride [AMCA-MIL-53(Al)] metal organic framework (MOF) and its potential application in sequestering toxic lead [Pb(II)] from aqueous phase was tested. Characterization studies affirmed successful AMCA-MIL-53(Al) formation. Experimental parameters viz., pH, contact time, Pb(II) concentration, temperature, and AMCA-MIL-53(Al) dose have a profound influence on adsorption. The maximum adsorption of Pb(II) on AMCA-MIL-53(Al) was 390 mg/g, observed at 318 K. Modeling studies revealed fitting of Langmuir isotherm and Lagergren's pseudo-first-order kinetic models to experimental data. Mechanistically, the adsorption was governed by amide and carboxylate groups through coordinate and electrostatic bonds formations. Desorption studies showed 79.5% (maximum) Pb(II) recovery with 0.1 M HCl. Thus, it could be concluded that the developed AMCA-MIL-53(Al) MOF is an excellent adsorbent for an efficient and rapid Pb(II) removal and recovery.
      Graphical abstract image

      PubDate: 2017-11-17T05:43:04Z
      DOI: 10.1016/j.micromeso.2017.11.016
      Issue No: Vol. 261 (2017)
       
  • Rapid one-pot synthesis of ultrafine titania nanocrystals and their
           conversion into transparent mesoporous thin layer films
    • Authors: Yoshitaka Kumabe; Masataka Ohtani; Kazuya Kobiro
      Pages: 207 - 213
      Abstract: Publication date: 1 May 2018
      Source:Microporous and Mesoporous Materials, Volume 261
      Author(s): Yoshitaka Kumabe, Masataka Ohtani, Kazuya Kobiro
      Ultrafine titania nanocrystals were synthesized using a rapid heating, one-pot solvothermal method. These nanocrystals are extremely small with a narrow size distribution (3.0 ± 0.4 nm). The detailed structural analysis by using transmission electron microscopy reveals periodic alignment of the resultant titania nanocrystals with hexagonal symmetry due to their size uniformity. The drop-casting deposition and calcination of these nanocrystals are also enable to convert into mesoporous thin layer films with nano convex-concave surface. The resultant transparent mesoporous thin layer exhibits not only anti-reflection properties but also high photocatalytic activity.
      Graphical abstract image

      PubDate: 2017-11-17T05:43:04Z
      DOI: 10.1016/j.micromeso.2017.11.013
      Issue No: Vol. 261 (2017)
       
  • Synthesis of mesoporous silica-included heteropolyacids materials and the
           utilization for the alkylation of phenol with cyclohexene
    • Authors: Yongxing Yang; Guangqiang Lv; Wei Guo; Limin Zhang
      Pages: 214 - 219
      Abstract: Publication date: 1 May 2018
      Source:Microporous and Mesoporous Materials, Volume 261
      Author(s): Yongxing Yang, Guangqiang Lv, Wei Guo, Limin Zhang
      Mesoporous silica-included heteropolyacids materials were synthesized and characterized by nitrogen sorption, XRD, FT-IR, TEM and NH3-TPD. Characterization results show that silica included heteropolyacids is a kind of Bronsted acid catalyst possessing large surface area, suitable pore structure, appropriate acid strength and high acid density. These materials are used as solid catalysts for the alkylation of phenol with cyclohexene. The mesoporous channel facilitates not only the dispersion of Bronsted acidity centers but also the transport of reactant and product molecules, thus leading to a significantly improved catalytic performance. Through adjusting the interaction between the support pore channel surface and heteropolyacid acive species, different acidity amount and strength can be obtained, leading to the tunable selectivity to the alkylation of phenol with cyclohexene. The improvement of reusability of silica-included HPA catalyst was related to the uniform dispersion of HPA and the enhanced interaction between HPA and the support. In six cycles of the catalyst, a stable activity could be mainttained.
      Graphical abstract image

      PubDate: 2017-11-17T05:43:04Z
      DOI: 10.1016/j.micromeso.2017.11.018
      Issue No: Vol. 261 (2017)
       
  • Preparation and composition analysis of catalysts supported by
           CuO-CoO-MnO/SiO2 nanocomposite aerogels
    • Authors: Yueqing Zhao; Xizhe Zhao; Mingxi Zhang; Qianyi Jia
      Pages: 220 - 226
      Abstract: Publication date: 1 May 2018
      Source:Microporous and Mesoporous Materials, Volume 261
      Author(s): Yueqing Zhao, Xizhe Zhao, Mingxi Zhang, Qianyi Jia
      Using tetraethyl orthosilicate (TEOS) as Si source, and aqueous solution of Cu, Co and Mn acetates as the precursors, CuO-CoO-MnO/SiO2 nanocomposite aerogels were prepared through different methods, such as sol-gel process, CO2 supercritical drying (SCD) technique, and ethanol SCD technique, respectively. Catalysts supported by the nanocomposite aerogels were prepared by impregnation method. They were used in the synthesis of diphenyl carbonate (DPC). The microstructures of the nanocomposite aerogels and the catalysts were observed with transmission electron microscopy (TEM). The specific surface area, pore size and pore size distribution of the nanocomposite aerogels were determined by the Brunauer–Emmett–Teller (BET) method. The compositions of the nanocomposite aerogels and the catalysts were analyzed by energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The results show that nanocomposite aerogel prepared by ethanol SCD technique shows lower transition metals loss compared with that through CO2 SCD technique. The mole fraction of active transition metals in the nanocomposite aerogel prepared through ethanol SCD technique is 13.77 mol%, and that in the ultrafine particles of the nanocomposite aerogel is 67.65%. The mole fraction of active transition metals decreased to some extent after it was used as a catalyst carrier in the synthesis of DPC. The yield of DPC catalyzed by the novel supported catalyst is 26.31 mass%, which is much higher than other porous carriers, such as SiO2 xerogels, SiO2 aerogels, CuO/SiO2 composite xerogels, CuO/SiO2 composite aerogels and CuO-CoO-MnO/SiO2 composite xerogels synthesized in this study.
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      PubDate: 2017-11-17T05:43:04Z
      DOI: 10.1016/j.micromeso.2017.11.017
      Issue No: Vol. 261 (2017)
       
  • Overgrowth of lamellar silicalite-1 on MFI and BEA zeolites and its
           consequences on non-oxidative methane aromatization reaction
    • Abstract: Publication date: June 2018
      Source:Microporous and Mesoporous Materials, Volume 263
      Author(s): Yiqing Wu, Laleh Emdadi, Emily Schulman, Yuying Shu, Dat T. Tran, Xizheng Wang, Dongxia Liu
      The combination of two compositionally and/or structurally different zeolites into one single zeolite composite particle is a potential approach to integrate advantages of different zeolite structures for desirable properties and applications. In the present study, we report the overgrowth of lamellar mesoporous silicalite-1 on the commercial microporous MFI and BEA zeolites, respectively, to render hierarchical meso-/microporous lamellar silicalite-1/MFI (L-Si/MFI) and lamellar silicalite-1/BEA (L-Si/BEA) zeolite composites via hydrothermal crystallization of lamellar silicalite-1 with the assistance of a diquaternary ammonium template. Epitaxial growth of lamellar silicalite-1 on commercial bulk MFI was observed, resulting in the L-Si/MFI zeolite composite as porcupine sensory message ball with nerve-stimulating silicalite-1 bumps extended from the MFI particle. In the L-Si/BEA zeolite composite, the lamellar silicalite-1 was laid over the surface of or partially interdigitated into the commercial bulk BEA particle, forming a BEA nanosponge structure connected to lamellar silicalite-1 nanosheets. The resultant interconnected micro- and mesoporosity in the L-Si/MFI and L-Si/BEA composite zeolites allowed facile mass transport of bulky molecules. The acid sites sitting on the external surface of commercial MFI and BEA zeolites were partially passivated by the lamellar silicalite-1. The consequences of improved mass transport and passivation of external acid sites on the catalytic performance of these zeolite composites were tested in 2 wt% molybdenum (Mo) loaded L-Si/MFI and L-Si/BEA for direct non-oxidative methane aromatization reaction, which showed higher methane conversion and hydrocarbon product formation as well as higher selectivity to naphthalene and coke in comparison with 2 wt% Mo-loaded commercial MFI and BEA catalysts.
      Graphical abstract image

      PubDate: 2017-12-12T08:22:26Z
       
  • The effect of Co and N of porous carbon-based materials fabricated via
           sacrificial templates MOFs on improving DA and UA electrochemical
           detection
    • Abstract: Publication date: June 2018
      Source:Microporous and Mesoporous Materials, Volume 263
      Author(s): Hailing Guo, Mei Wang, Lei Zhao, Nuerguli Youliwasi, Chenguang Liu
      N and Co-doped carbon particles (NCCNPs) were prepared by directly carbonizing ZIF-67 at different temperature. The obtained NCCNPs were modified on glassy carbon electrodes (GCE) for electrochemical detection of dopamine (DA) and uric acid (UA). NCCNPs synthesized at 800 °C modified electrode exhibited the highest sensitivity and lowest detection limit toward DA and UA. The effect of the form and content of N, Co species on the detection performance were deduced. It was found that the excellent electrochemical sensing performance of the NCCNPs800 modified electrode is related with large amount of Co with high crystallinity, the small amount of doped N with high electron acceptance ability.
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      PubDate: 2017-12-12T08:22:26Z
       
  • Nanostructured silver silica materials as potential propolis carriers
    • Abstract: Publication date: June 2018
      Source:Microporous and Mesoporous Materials, Volume 263
      Author(s): Margarita Popova, Hristina Lazarova, Boryana Trusheva, Milena Popova, Vassya Bankova, Judith Mihály, Hristo Najdenski, Iva Tsvetkova, Ágnes Szegedi
      It is reported for first time, that silver modified nanoporous MCM-41 or SBA-15 silicas are promising carriers for the preparation of poplar propolis loaded dermal formulations. MCM-41 or SBA-15 were successfully modified with 5–15 nm sized silver nanoparticles by direct or post synthesis methods. The formed silver nanoparticles are stabilized in the channels or on the outer surface of nanoporous supports. Poplar propolis molecules were loaded into the mesoporous channels by impregnation. The parent and poplar propolis loaded formulations were characterized by powder XRD, N2 physisorption, thermal analysis and ATR FT-IR spectroscopy. In vitro release of poplar propolis and silver was studied in phosphate buffer at pH = 5.5 which is typical for dermal formulations. Adsorption of poplar propolis on nanoporous silica particles significantly improves its water solubility. Moreover propolis loaded silver-silica systems show significantly better antibacterial and antifungal activities than poplar propolis and silver-modified carriers themselves.
      Graphical abstract image

      PubDate: 2017-12-12T08:22:26Z
       
  • Computational study of ethanethiol conversion reactions catalyzed by
           acidic zeolites
    • Abstract: Publication date: 15 May 2018
      Source:Microporous and Mesoporous Materials, Volume 262
      Author(s): D.K. Papayannis, A.M. Kosmas, N. Tsolakis
      The reaction mechanism, of the ethanethiol transformation over acidic zeolite surface: ethanethiol-Hp-zeolite → Hp-zeolite + ethene + H2S, has been investigated computationally with the use of ab initio, density functional theory (DFT) and MM methods. The investigation has been carried out by employing two model zeolite clusters, each including one hydroxyl Brønsted acidic site (BAS). The first model, denoted 20T, has been studied with the help of the two-layered ONIOM2 (M06-2X/6-31 + G(d,p):UFF) methodology and the second one denoted 38T, has been investigated using the three-layered ONIOM3 (M06-2X/6-31 + G(d,p):HF:UFF) approach. The calculations using both models show that the reaction mechanism involves two competing channels, a direct t2 type dehydrosulfidation (DHS) channel, and a stepwise Sw2 type pathway through the intermediate formation of an alkoxy species. The detailed examination of the two pathways, i.e., the direct mechanism and the stepwise mechanism, indicate that the latter is strongly favored over the direct t2 type mechanism. Finally, the consistency of the results from both methodologies suggests that the ONIOM approach yields an accurate and practical method to study the degradation mechanism of sulfur containing compounds on acidic zeolite surface.
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      PubDate: 2017-12-12T08:22:26Z
       
  • High-quality graphene sheets decorated with ZIF-8 nanocrystals
    • Abstract: Publication date: 15 May 2018
      Source:Microporous and Mesoporous Materials, Volume 262
      Author(s): Theodore Tsoufis, Christos Tampaxis, Ioannis Spanopoulos, Theodore Steriotis, Fotios Katsaros, Georgia Charalambopoulou, Pantelis N. Trikalitis
      Excellent-quality graphene sheets produced via the direct liquid phase exfoliation of highly crystalline graphite (avoiding any oxidative treatment), were employed for the first time as 2D scaffolds for the in-situ synthesis of zeolitic-imidazolate-framework (ZIF-8) material. Our synthetic approach involved the efficient, urea-assisted exfoliation of natural graphite (without using any acids), and the subsequent selective, mild functionalization of the resulting high-quality graphene sheets with benzoic acid functional groups. The graphene derivatives were next decorated via the in-situ development of ultrasmall (approx. 30 nm) ZIF-8 nanocrystals. We discuss the critical role of the functionalized graphene to the selective nucleation and crystal growth of ZIF-8 nanocrystals exclusively at their surface. In-depth gas sorption studies of different gases revealed that the novel ZIF-8@Graph nano-composites exhibited improved porosity (in terms of surface area and pore volume) compared to analogous Graphene Oxide/ZIF-8 hybrids. In addition, the gate effect of the ZIF-8 nanocrystals anchored onto the high-quality graphene, was found very different compared to bulk ZIF-8, a behavior that is attributed mainly to the significantly smaller crystal size and the perfect 2D confinement of ZIF-8 along graphene. Finally, preliminary CO2 adsorption properties of the synthesized novel nano-composites are reported, at near ambient temperature.
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      PubDate: 2017-12-12T08:22:26Z
       
  • The influence of the functional group on activated carbon for acetone
           adsorption property by molecular simulation study
    • Abstract: Publication date: 15 May 2018
      Source:Microporous and Mesoporous Materials, Volume 262
      Author(s): Xiaoyi Liang, Junjie Chi, Zhen Yang
      In this paper, different types and amounts of oxygen functional groups are inserted in graphitic slit pores to investigate the individual effect of each factor, which aims to clarify the effects of functional groups in activated carbon on acetone adsorption based on molecular simulation. Adsorption isotherms of acetone are then calculated by using Grand Canonical Monte Carlo (GCMC) simulation. Simulation results show that acetone adsorption capacity is increased at low fugacity after inserting oxygen-containing functional groups, however, equilibrium adsorption capacity is decreased. Along with the increase of amounts of functional group, the acetone adsorption loading is not always increased due to the reduction of available adsorption sites on pore wall. Also, it is concluded that trace acetone (10ppmv) is adsorbed mainly in 1.0 nm pore, in which the oxygen content is 5 wt% and the functional group planted in is hydroxyl that is the most beneficial one to trace acetone adsorption.
      Graphical abstract image

      PubDate: 2017-12-12T08:22:26Z
       
  • Ni based catalyst supported on KIT-6 silica for CO methanation:
           Confinement effect of three dimensional channel on NiO and Ni particles
    • Abstract: Publication date: 15 May 2018
      Source:Microporous and Mesoporous Materials, Volume 262
      Author(s): Yuhao Lv, Zhong Xin, Xin Meng, Miao Tao, Zhicheng Bian
      Several nickel catalysts supported on silica KIT-6 were synthesized via the incipient wetness impregnation method and the performance of the catalysts in CO methanation were investigated in a continuous flow fixed bed reactor. The mesoporous silica KIT-6 has three dimensional framework and large surface area, which can offer adequate sites for the metal to disperse. The amount of nickel loading has significantly affected the metal surface area and dispersion of nickel particles on the support. The catalysts with higher Ni loading exhibited better activity in CO methanation. It was also found that, compared with Al2O3, SiO2 and even meseporous SBA-15, KIT-6 silica has an obvious confinement effect to NiO particles as the size of NiO particles maintained consistent under different calcination temperature. However, at higher temperature, metallic nickel particles sintered due to the Ostwald ripening effect, which caused the pore blocking of the support and further led to the deactivation of the catalysts.
      Graphical abstract image

      PubDate: 2017-12-12T08:22:26Z
       
  • Enhanced CO2 adsorption in nano-ZIF-8 modified by solvent assisted ligand
           exchange
    • Abstract: Publication date: 15 May 2018
      Source:Microporous and Mesoporous Materials, Volume 262
      Author(s): Chih-Wei Tsai, J.W. Niemantsverdriet, Ernie H.G. Langner
      The organic linkers of Zeolitic Imidazole Framework-8 (ZIF-8) nanoparticles influence its adsorption of CO2 gases. Solvent Assisted Ligand Exchange (SALE) was successfully used to exchange ∼ 13% of the 2-methylimidazolate linkers of ZIF-8 nanoparticles with 2-mercaptobenzimidazole, 2-aminobenzimidazole or 2-phenylimidazole. With 2-nitroimidiazole ∼67% exchange was achieved, since no bulky benzyl groups were present. During SALE treatment the SOD (sodalite zeolitic framework type) topology of ZIF-8 was maintained, but after the higher exchange percentage of 2-nitroimidazole an frl topology was observed. Up to a two-fold increase in CO2 adsorption was recorded after SALE of ZIF-8 with imidazole derivatives containing NO2 and SH electron withdrawing functional groups. In the case of 2-aminobenzimidazole only a moderate increase in CO2 adsorption was observed.
      Graphical abstract image

      PubDate: 2017-12-12T08:22:26Z
       
  • Preparation of packing type catalysts AAO@Al/Meso-SiO2-SO3H for the
           dehydration of xylose into furfural
    • Abstract: Publication date: 15 May 2018
      Source:Microporous and Mesoporous Materials, Volume 262
      Author(s): Shaojian Hu, Jianhua Zhu, Yulong Wu, Ruirong Xie, Kejing Wu, Mingde Yang
      This work is focused on preparation of packing type catalyst for dehydration of xylose into furfural. Different preparation methods such as liquid phase synthesis and evaporation-induced self-assembly (EISA) synthesis were considered. A series of sulfonated mesoporous catalysts were prepared through EISA synthesis to optimise high-active components, such as FDU-5-SO3H, SBA-15-SO3H, and SBA-16-SO3H. Results show that the superior catalyst FDU-5-7.5E-SO3H with a xylose conversion of 96.81% and a furfural selectivity of 81.11% stood out at a reaction temperature of 160 °C. Packing type catalysts with various morphologies, such as particle, nanotube and nanorod were synthetized. The results of SEM indicated that the degassing treatments were significant ways to enhance filling rate and EISA synthesis was effective to improve the morphology. According to the work mentioned above, packing type catalyst AAO@Al/FDU-5-7.5E-SO3H with xylose conversion of 94.85% and furfural selectivity of 66.19% was prepared. Mechanical and thermal stability tests demonstrated that packing type catalyst had a strong application feasibility in a continuous reactor.
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      PubDate: 2017-12-12T08:22:26Z
       
  • Combined steam and CO2 reforming of methane for syngas production over
           carbon-resistant boron-promoted Ni/SBA-15 catalysts
    • Abstract: Publication date: 15 May 2018
      Source:Microporous and Mesoporous Materials, Volume 262
      Author(s): Tan Ji Siang, Thong L.M. Pham, Nguyen Van Cuong, Pham T.T. Phuong, Nguyen Huu Huy Phuc, Quang Duc Truong, Dai-Viet N. Vo
      The unpromoted and B-promoted 10%Ni/SBA-15 catalysts synthesized via sequential incipient wetness impregnation approach were assessed for combined steam and CO2 reforming of methane (CSCRM) at various reaction temperatures of 973–1073 K and stoichiometric feed composition. An expected and noteworthy drop in mean NiO crystallite size and BET surface area with boron promotion from 1% to 5%B loading could be due to the agglomeration of B2O3 particles and deboration reaction during calcination and hence blocking mesopores of SBA-15 support at elevated B composition. The complete NiO reduction to metallic Ni0 form was achieved during H2 activation and the reduction temperature of NiO phase was shifted towards higher temperature with B-addition owing to enhancing interaction between the acidic B2O3 and basic NiO phases. For all reaction temperature employed, 3%B appeared to be the optimal promoter loading in terms of reactant conversions and 3%B-10%Ni/SBA-15 catalyst revealed the greatest H2 yield (69.4%) at 1073 K. In addition, CH4 and CO2 conversions were enhanced about 23.2% and 32.4%, correspondingly with rising reaction temperature from 973 to 1073 K. Ratio of H2 to CO varied from 1.26 to 2.71 and the desired H2/CO ratio of about 2 favored for Fischer-Tropsch synthesis was achieved on 3%B-10%Ni/SBA-15 sample at 973 K. Boron promoter suppressed graphitic carbon formation and the amount of carbonaceous deposition was reduced about 4 times. Noticeably, 3%B-10%Ni/SBA-15 was also resilient to metallic Ni0 re-oxidation throughout CSCRM.
      Graphical abstract image

      PubDate: 2017-12-12T08:22:26Z
       
  • Zeolite catalyzed palmitic acid esterification
    • Abstract: Publication date: 15 May 2018
      Source:Microporous and Mesoporous Materials, Volume 262
      Author(s): Pepijn Prinsen, Rafael Luque, Camino González-Arellano
      The present study compares four commercial H-Y and ZSM-5 zeolites as solid acid catalysts for the conversion of palmitic acid to methyl palmitate under smooth conditions. The palmitic acid conversion did not show a clear correlation with the amount of acid sites on the catalysts surface and depended more on the porosity and the hydrophobic/hydrophilic balance of the microporous materials and the reactants. Only the H-Y-60 catalyst was highly effective for this reaction, yielding 100% conversion after 3 h at 70 °C using a 2:1 M ratio of metanol:palmitic acid, with approximately 3 μmol of catalytic acid sites per mmol of palmitic acid, and exhibiting promising recyclability.
      Graphical abstract image

      PubDate: 2017-12-12T08:22:26Z
       
  • Synthesis of high-surface-area rod-like alumina materials with enhanced
           Cr(VI) removal efficiency
    • Abstract: Publication date: 15 May 2018
      Source:Microporous and Mesoporous Materials, Volume 262
      Author(s): Xiangyu Xu, Qingquan Yu, Zhi Lv, Jiaqing Song, Mingyuan He
      A facile synthesis of rod-like alumina materials was developed through systematical investigation, which enables the control of the specific surface area of ammonium aluminium carbonate hydroxide (AACH) using aluminum nitrate as a precursor and urea as a precipitant. Our studies indicated that the molar ratio of CO(NH2)2/Al influences crystallinity, morphology and the surface area of alumina materials. Amorphous alumina materials with nanorod morphology and high surface area (1029 m2 g-1) was obtained with 15:1 M ratio of CO(NH2)2 to Al. In addition, the results demonstrated that thermal behaviors of the as-prepared AACH affect their crystallinities. Furthermore, the amorphous Al2O3 prepared from AACH by calcination at 773 K was used as an adsorbent for Cr(VI) removal from water solution, and external factors were investigated, including contact time, adsorbent dosage, initial concentration of adsorbate and the pH of solution. It was found that the maximum adsorption capacity of prepared amorphous Al2O3 for Cr(VI) was 52.1 mg g−1, which was higher than those of other reported Al2O3 samples.
      Graphical abstract image

      PubDate: 2017-12-12T08:22:26Z
       
  • Microwave synthesis of hierarchical porous materials with various
           structures by controllable desilication and recrystallization
    • Abstract: Publication date: 15 May 2018
      Source:Microporous and Mesoporous Materials, Volume 262
      Author(s): Xiao-Lin Luo, Fei Pei, Wei Wang, Hua-ming Qian, Kang-Kang Miao, Zhe Pan, Ya-Shao Chen, Guo-Dong Feng
      Hierarchical porous materials with controllable structures are efficiently synthesized through a one-step approach by adjusting the detemplation degree of the parent zeolites. Partial removal of the template from the micropores provides an opening framework in ZSM-5 for subsequent desilication in alkaline solution by microwave digestion, while the template-containing regions are restrained from silicon leaching. OH− ions are consumed during Si leaching to provide favorable pH for the crystallization of mesoporous structures. Consequently, mesoporous silica shells are coated on the partially detemplated zeolites to form the hierarchical structures, and the parent microporous core with the residual template is immune to desilication. The structures of the hierarchical porous materials are susceptible to the detemplation degree of the pristine zeolite. The surface area and pore volume of the hierarchical porous materials are enhanced greatly compared with those of the pristine ZSM-5 because of the large contribution of the mesopores.
      Graphical abstract image

      PubDate: 2017-12-12T08:22:26Z
       
  • Short channeled Ni-Co/SBA-15 catalysts for highly selective hydrogenation
           of biomass-derived furfural to tetrahydrofurfuryl alcohol
    • Abstract: Publication date: 15 May 2018
      Source:Microporous and Mesoporous Materials, Volume 262
      Author(s): Shuai Li, Yuan Wang, Lijing Gao, Yuanfeng Wu, Xinhui Yang, Pengxin Sheng, Guomin Xiao
      Liquid phase and one-step reaction for furfural (FFR) hydrogenated to tetrahydrofurfuryl alcohol (THFA) was conducted by employing noble metal-absence and toxicity-free, bimetallic Ni-Co catalysts. The bimetallic Ni-Co catalysts with different molar ratio of Ni to Co and two monometallic catalysts (Ni, Co) were synthesized by conventional incipient-wetness impregnation method with short channeled SBA-15 as support. Among these catalysts, highly selective hydrogenation of FFR to THFA was attained over Ni-Co/SBA-15 catalysts. The impact of molar ratio of Ni/Co was studied with a fixed Ni loading (10 wt %) in bare support. The samples were characterized by N2 sorption, XRD, XPS, H2-TPR, SEM, TEM and CO chemisorption. The results confirmed that the reducibility of Ni-catalysts can be improved by incorporating Co metal and revealed that appropriate amount of spinel NiCo2O4 oxides is favorable to uniform and high dispersion of Ni0 and CoO over short channeled SBA-15, which would be benefit for the catalytic performance. For catalytic activity investigation, other four mesoporous SiO2 materials (MCM-41, MCM-4, MCF-2 and common SBA-15) were employed as supports to investigate the effect on the hydrogenation of FFR and the reaction parameters including the reaction temperature, initial of H2 pressure, reaction time and the reusability of the catalysts were also studied. 100% of FFR conversion and 92.1% of THFA selectivity were achieved at 90 °C, 50 bar of initial H2 and 2.0 h over catalyst Ni-Co/SBA-15 when the molar ratio of Ni to Co was 0.67.
      Graphical abstract image

      PubDate: 2017-12-12T08:22:26Z
       
  • One-pot synthesis of large-pore AlMCM-41 aluminosilicates with high
           stability and adjustable acidity
    • Abstract: Publication date: 15 May 2018
      Source:Microporous and Mesoporous Materials, Volume 262
      Author(s): Hessam Ziaei-Azad, Joel M. Kolle, Nabil Al-Yasser, Abdelhamid Sayari
      We report for the first time, a novel one-pot protocol for the synthesis of large-pore AlMCM-41 aluminosilica materials (i.e. LP-AlMCM-41(y), where y = Si/Al ratio). Assisted by a pore-expansion agent, i.e. N,N-dimethylhexadecylamine (DMHA) and the self-assembly process, aluminum incorporation and pore-enlargement were achieved in a single step, eliminating costly post-synthesis treatments. The LP-AlMCM-41s and the corresponding protonated materials, i.e. LP-H-AlMCM-41, were thoroughly characterized by ICP, N2 adsorption-desorption, TEM, 27Al MAS NMR and FT-IR of adsorbed pyridine. The LP-AlMCM-41 materials exhibited relatively sharp and uniform pore size distribution profiles, BET surface areas of around 1000 m2/g and average pore diameters of 6–7 nm. No dealumination or structural degradation was observed upon pore-enlargement of AlMCM-41, which is a unique feature of this methodology. As opposed to purely siliceous LP-MCM-41, the LP-AlMCM-41(20) showed structural stability toward prolonged exposure to boiling water and steam. Thus, it is anticipated to be a good candidate for adsorption applications in aqueous media as well in processes utilizing steam for regeneration. Upon protonation, the catalytic activity of LP-H-AlMCM-41s was investigated in the acid-catalyzed reaction of furfural with 2-methylfuran to produce 2,2’-(2-furylmethylene)bis(5-methylfuran) (FMBM). A superior catalytic performance was observed in the presence of LP-H-AlMCM-41(20), showing 49% furfural conversion with 71% selectivity to FMBM. Owing to the high BET surface areas and pore volumes as well as the large and uniform pore diameters preserved after protonation, these LP-H-AlMCM-41 aluminosilicates can be potential candidates for catalytic processes involving complex molecular structures such as petroleum heavy oil and biomass.
      Graphical abstract image

      PubDate: 2017-12-12T08:22:26Z
       
  • Development and optimization of alumina fine fibers utilizing a
           centrifugal spinning process
    • Abstract: Publication date: 15 May 2018
      Source:Microporous and Mesoporous Materials, Volume 262
      Author(s): Mandana Akia, Dulce Capitanachi, Misael Martinez, Carlos Hernandez, Hector de Santiago, Yuanbing Mao, Karen Lozano
      Aluminum isopropoxide and poly(vinylalcohol) fine fibers were successfully fabricated and optimized utilizing the response surface methodology. The optimized composite fibers showed mean fiber diameter of 304 nm. The fiber samples were calcined at different temperatures to attain both gamma and alpha phases of alumina. Various characterization methods including scanning electron microscopy, thermogravimetric analysis, x-ray diffraction and nitrogen adsorption/desorption analysis were conducted. The BET analysis revealed a surface area of 261 m2g-1 for the mesoporous gamma alumina structure. Statistical analysis of electron microscopy micrographs showed a mean fiber diameter of 272 nm for the crystalline alpha alumina fine fibers, calcined at 1200 °C.
      Graphical abstract image

      PubDate: 2017-12-12T08:22:26Z
       
  • Confined-space synthesis of hierarchical MgAPO-11 molecular sieves with
           good hydroisomerization performance
    • Abstract: Publication date: 15 May 2018
      Source:Microporous and Mesoporous Materials, Volume 262
      Author(s): Shuo Tao, Xiaolei Li, Huimin Gong, Qike Jiang, Wenguang Yu, Huaijun Ma, Renshun Xu, Zhijian Tian
      Hierarchical MgAPO-11 molecular sieves with large BET surface areas and high pore volumes have been synthesized via dry-gel conversion of the magnesioaluminophosphate-carbon (MAP-C) composites. The carbon film coated on the mesopores of amorphous magnesioaluminophosphate (MAP) provides a confined-space to restrict the overgrowth of the crystals. The products were well characterized using XRD, SEM, TEM, N2 adsorption-desorption, infrared spectroscopy of pyridine adsorption (Py-IR) and solid-state NMR techniques. The results show that highly mesoporous MgAPO-11 with good crystallinity can be obtained at an appropriate carbon loading amount. The time-dependent study indicates that the formation process of hierarchical MgAPO-11 obeys a reversed crystal growth route: crystallization started on the outer surface of the amorphous precursor, then extended to inward, and finally hierarchical molecular sieves assembled by nanosized crystals with a size of about 50 nm were obtained. The catalyst based on hierarchical MgAPO-11 exhibits a significant higher activity and selectivity than the conventional Pt/MgAPO-11 catalyst in the hydroisomerization of n-dodecane, attributing to its higher acidity and excellent diffusion properties resulting from the hierarchical pore architecture.
      Graphical abstract image

      PubDate: 2017-12-12T08:22:26Z
       
  • Encapsulating V2O3 nanorods into carbon core-shell composites with porous
           structures and large specific surface area for high performance
           solid-state supercapacitors
    • Abstract: Publication date: 15 May 2018
      Source:Microporous and Mesoporous Materials, Volume 262
      Author(s): Tao Hu, Yanyan Liu, Yifu Zhang, Ying Nie, Jiqi Zheng, Qiushi Wang, Hanmei Jiang, Changgong Meng
      V2O3@C core-shell nanorods with porous structures and large specific surface area were synthesized using V2O5 nanowires as the source of core and glucose as the source of shell by a facile hydrothermal route combination of heat treatment. As-prepared V2O3@C nanorods comprised of core-shell structures with crystalline V2O3 cores and amorphous carbon shells. Nitrogen adsorption-desorption isotherms revealed that V2O3@C core-shell nanorods displayed BET specific surface area as high as 219 m2·g−1 and had hierarchical porous structures. Electrochemical properties of V2O3@C core-shell nanorods as supercapacitor electrode were studied and showed their measured capacitance was based on the pseudocapacitance. Specific capacitances of V2O3@C core-shell nanorods measured 228, 221, 207, 158 and 127 F·g−1 at current densities of 0.5, 1, 2, 5 and 10 A·g−1, respectively. Results showed V2O3@C core-shell nanorods displayed higher specific capacitance than values of carbon spheres (4 F·g−1 at 1 A·g−1) and V2O3 nanomaterials (49 F·g−1 at 1 A·g−1). Asymmetric supercapacitor device assembled from V2O3@C core-shell nanorods and activated carbon (V2O3@C//C) showed specific capacitances of 0.297, 0.274, 0.230, 0.194 and 0.169 F·cm−2 at current densities of 0.5, 1, 2, 5 and 10 mA·cm−2, respectively. It showed higher specific capacitance than that of V2O3//C device (0.219 F·cm−2 at 1 mA·cm−2). A capacitance retention of 86% for V2O3@C//C device after 1000 cycles indicated that V2O3@C had good cycling performance for supercapacitor application. Present findings suggested that V2O3@C core-shell nanorods could be considered as potential materials for high-performance energy storage materials.
      Graphical abstract image

      PubDate: 2017-12-12T08:22:26Z
       
  • Copper supported β-cyclodextrin functionalized PEGylated mesoporous
           silica nanoparticle -graphene oxide hybrid: An efficient and recyclable
           nano-catalyst for straightforward synthesis of 2-arylbenzimidazoles and
           1,2,3-triazoles
    • Abstract: Publication date: 15 May 2018
      Source:Microporous and Mesoporous Materials, Volume 262
      Author(s): Saeed Bahadorikhalili, Leila Ma'mani, Hossein Mahdavi, Abbas Shafiee
      β-Cyclodextrin functionalized PEGylated mesoporous silica nanoparticles-graphene oxide hybrid has been introduced as a heterogeneous support for immobilization of copper catalyst (denoted as Cu@βCD-PEG-mesoGO). Mesoporous silica nanoparticles-graphene oxide hybrid (mesoGO) was synthesized and functionalized by PEG600 ended β-cyclodextrin. Then, Cu was immobilized onto the later modified nanoparticles. Cu@βCD-PEG-mesoGO was evaluated for the synthesis of benzimidazoles and 1,2,3-triazoles. The synthesis of 2-aryl benzimidazole derivatives from o-phenylenediamines and benzaldehydes via aerobic C-N bond oxidation reaction was successfully performed using Cu@βCD-PEG-mesoGO as a “green” catalyst. The catalyst was also applied for the synthesis of 1,2,3-triazole derivatives via three component click reaction of alkynes, benzylbromides and sodium azide. The catalyst recovery test was performed, and showed that this catalyst is highly reusable without a significant decrease in its activity. This catalyst has outstanding properties such as high efficiency and turnover frequency (TOF), simple product work-up, utilization of H2O as a green solvent, mild reaction conditions, and easy catalyst recovery.
      Graphical abstract image

      PubDate: 2017-12-12T08:22:26Z
       
  • Synthesis of hierarchically porous silicate-1 and ZSM-5 by hydrothermal
           transformation of SiO2 colloid crystal/carbon composites
    • Abstract: Publication date: 15 May 2018
      Source:Microporous and Mesoporous Materials, Volume 262
      Author(s): Ping Liu, Li-Na Jin, Chun Jin, Jia-Nan Zhang, Shao-Wei Bian
      Hierarchically porous silicate-1 and ZSM-5 zeolites were successfully prepared by a hydrothermal crystallization process in the presence of SiO2 colloid crystal/carbon composite. The inter-crystalline mesopores and macropores were successfully created inside these zeolite materials. The effect of synthesis conditions including hydrothermal reaction temperature, reaction time, silica source and aluminum source on the morphology and porous structure were studied in detailed. All the samples were characterized by XRD, SEM, N2 adsorption-desorption analysis and NH3-TPD. The advantage of hierarchically porous structure was evaluated by the catalytic application. The hierarchically porous ZSM-5 as a catalyst displayed higher catalytic activity than the conventional ZSM-5 when using the acetalization reaction of cyclohexanone as a model reaction.
      Graphical abstract image

      PubDate: 2017-12-12T08:22:26Z
       
  • Catalytic performance of surface-silylated and phenyl-bridged
           Ti-containing mesoporous silica for epoxidation of propylene
    • Abstract: Publication date: 15 May 2018
      Source:Microporous and Mesoporous Materials, Volume 262
      Author(s): Xiaoyu Zhang, Yibin Huang, Yiman Guo, Xia Yuan, Feipeng Jiao
      Titanium-doped phenyl-bridged ordered mesoporous organosilicon (Ti-PMO) was initially prepared by a one-step hydrothermal synthesis method under acidic conditions. Following silanization modification, a Ti-PMO-S sample was obtained with an improved surface hydrophobic characteristic. The environment of titanium within the samples was analyzed by Fourier-transform infrared spectroscopy (FT-IR), diffuse reflectance ultraviolet-visible spectroscopy (UV-Vis-DR), ammonia temperature programmed desorption (NH3-TPD), and Raman spectroscopy. Furthermore, the textural and structural properties of corresponding materials were characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption isotherms and transmission electron microscopy (TEM). The results showed that Ti-PMO-S has more active Ti centers than Ti-SBA-15 and Ti-PMO on the basis of maintaining the mesoporous structure of ordered channels, despite the presence of few TiO2 species. The catalytic performance of the synthesized samples was assessed in the epoxidation of propylene with tert-butyl hydroperoxide (TBHP) as an oxidant. The prepared Ti-PMO-S materials showed the best epoxidation performance under optimized conditions, with conversion of TBHP up to 95.8% and selectivity of propylene epoxide and tert butyl alcohol reaching 78.8% and 95.9%, respectively.
      Graphical abstract image

      PubDate: 2017-12-12T08:22:26Z
       
  • Ion-exchange modified zeolites X for selective adsorption desulfurization
           from Claus tail gas: Experimental and computational investigations
    • Abstract: Publication date: 1 May 2018
      Source:Microporous and Mesoporous Materials, Volume 261
      Author(s): Xi Chen, Benxian Shen, Hui Sun, Guoxiong zhan
      Zn, Co and Ag modified NaX zeolites were prepared by ion-exchange method and the post-synthesized samples were characterized using EDS, XRD, FT-IR, SEM and N2 adsorption. The selective adsorption performances for H2S and COS from Claus tail gas were evaluated in a fixed bed adsorption column. In addition, the underlying mechanism for H2S and COS adsorption on zeolites X was revealed by DFT computation. Among all the samples, AgX shows the most excellent adsorption performance, which shows the highest H2S and COS breakthrough adsorption capacities up to 1.53 mmol/g and 10.5 μmol/g, respectively. The used AgX zeolite can also be regenerated by thermal treatment at 350 °C under air atmosphere. The DFT study indicates that the S-M bond between H2S or COS and metal ion can be formed during the adsorption process. Furthermore, the Ag-sulfide complex shows the strongest S-M interaction, hence, benefits the adsorption of H2S and COS on Ag-exchanged zeolite X.
      Graphical abstract image

      PubDate: 2017-12-12T08:22:26Z
       
  • Metal-organic chemical vapor deposition of Cu(acac)2 for the synthesis of
           Cu/ZSM-5 catalysts for the oxidation of toluene
    • Abstract: Publication date: 1 May 2018
      Source:Microporous and Mesoporous Materials, Volume 261
      Author(s): Yong Zhang, Huiping Zhang, Ying Yan
      A heterogeneous catalyst (Cu/ZSM-5) was prepared by a metal-organic chemical vapor deposition (MOCVD) method under nitrogen atmosphere using Cu(acac)2 as the copper precursor, and further characterized by XRD, AAS, SEM, BET, H2-TPR and XPS as well as catalytic activity performance for the oxidation of toluene. N2 adsorption data revealed that the samples (CVD-4) prepared by MOCVD with calcination at 500 °C for 4 h possessed higher surface areas than that (CVD-BC) not calcined. The results of XPS demonstrated that CVD-4 exhibited higher redox property and more surface oxygen species compared with CVD-BC and IM (Cu/ZSM-5 catalyst prepared by impregnation). In particular, the CVD-4 catalysts prepared by MOCVD with calcinations showed the highest catalytic activity for toluene oxidation with 90% conversion of toluene at 293 °C with the feed concentration of 1000 ppm and GHSV of 15,000 h−1, which was lower than IM (310 °C). The results of a reaction durability test revealed that the Cu/ZSM-5 catalysts prepared by MOCVD possessed excellent durability for toluene oxidation for 63 h, while the conversion of toluene fell down from 90% to 60% after 48 h over IM catalyst.
      Graphical abstract image

      PubDate: 2017-12-12T08:22:26Z
       
  • Synthesis of ZIF-7, ZIF-8, ZIF-67 and ZIF-L from recycled mother liquors
    • Abstract: Publication date: 1 May 2018
      Source:Microporous and Mesoporous Materials, Volume 261
      Author(s): Fatma Şahin, Berna Topuz, Halil Kalıpçılar
      ZIF-8, ZIF-L, ZIF-7 and ZIF-67 were synthesized from fresh and recycled synthesis solutions. ZIF-8, ZIF-L and ZIF-7 includes Zn2+, while ZIF-67 includes Co2+. ZIF-7 was synthesized in dimethyl formamide, while the others in water. The organic linker was 2-methyl imidazole for ZIF-8, ZIF-L and ZIF-67, and benzimidazole for ZIF-7. The recycling was proceeded two steps for each type of ZIF. For the synthesis in the recycled solutions, the pH and the metal ion content of the mother liquor should be adjusted for a successful synthesis. All synthesis using fresh and recycled solutions resulted in highly crystalline ZIFs. The crystal morphology, N2 adsorption capacity and thermal behavior of ZIFs from recycled solutions were similar to those obtained from the fresh solution. The recycling procedures improved the efficiency of crystallization such that 0.36 g ZIF-7/g organic linker was obtained after two recycling steps, although only 0.16 g ZIF-7/g organic linker can be obtained after single step synthesis using fresh solution. From an environmental perspective, the developed procedures allowed to consume a great extent of organic linker used for synthesis, therefore the amount of waste organic linker was reduced.
      Graphical abstract image

      PubDate: 2017-12-12T08:22:26Z
       
  • LTL type nanozeolites utilized in surface photonics structures for
           environmental sensors
    • Abstract: Publication date: 1 May 2018
      Source:Microporous and Mesoporous Materials, Volume 261
      Author(s): Sabad-e Gul, Dervil Cody, Anastasia Kharchenko, Suzanne Martin, Svetlana Mintova, John Cassidy, Izabela Naydenova
      Environmental monitoring has been continuously increasing due to an emerging global emphasis on the importance of sustainable development. Improving water quality monitoring and control is a challenge that calls for innovative solutions. Current methods of water monitoring are costly and analytical techniques suitable for field use are limited. There is a need for accurate, long–term monitoring of environmental contaminants using sensors that can be operated on site. The aim of our research is to theoretically model, fabricate and characterise holographic sensors for water quality monitoring that are simple to operate, capable of sensing copper present in fresh water and have relatively low cost. The sensors are created by holographic recording of surface relief gratings (SRG) in a self-processing photopolymer material. Interrogation of these structures by light allows indirect measurements of ion concentration in real time. The SRG structures are modified by coating with porous LTL-nanoparticles (nanosized zeolites) which selectively adsorb copper ions. The suitability of the sensors for detection of copper (II) present in water at concentration levels 1–4 mM is reported. The current detection limit of the sensor is 63 ppm.
      Graphical abstract image

      PubDate: 2017-12-12T08:22:26Z
       
  • Preparation of SSZ-13 zeolites and their NH3-selective catalytic reduction
           activity
    • Authors: Lina Han; Xiaoge Zhao Huafeng Yongfeng Debao Dekui Sun Mengmeng
      Abstract: Publication date: 1 May 2018
      Source:Microporous and Mesoporous Materials, Volume 261
      Author(s): Lina Han, Xiaoge Zhao, Huafeng Yu, Yongfeng Hu, Debao Li, Dekui Sun, Mengmeng Liu, Liping Chang, Weiren Bao, Jiancheng Wang
      The effects of the Si/Al ratio in raw material and the crystallization process on the crystallinity and morphology of SSZ-13 zeolites synthesized by microwave, dynamic, and static hydrothermal methods were studied. After the ion exchange, the Cu-SSZ-13 catalysts were applied to the selective catalytic reduction (SCR) of NOx with NH3 and characterized by XRD, SEM, BET, H2-TPR, and NH3/NO-TPD. Microwave and dynamic hydrothermal methods can shorten the crystallization time, and the samples synthesized by these two methods showed excellent particle dispersion and a regular morphology. Furthermore, the samples prepared by microwave and dynamic hydrothermal methods have better ion exchange capacity and adsorption of NH3/NO, and the resulting Cu-SSZ-13 catalysts displayed excellent catalytic activity and hydrothermal stability.
      Graphical abstract image

      PubDate: 2017-11-17T05:43:04Z
       
  • Dehydration mechanism of AlPO4-5: A high-resolution synchrotron X-ray
           powder diffraction study
    • Authors: Michelangelo Polisi; Rossella Arletti Simona Quartieri Linda Pastero Carlotta Giacobbe
      Abstract: Publication date: 1 May 2018
      Source:Microporous and Mesoporous Materials, Volume 261
      Author(s): Michelangelo Polisi, Rossella Arletti, Simona Quartieri, Linda Pastero, Carlotta Giacobbe, Giovanna Vezzalini
      We present the results of a study on the thermal stability and dehydration dynamics of the porous aluminophosphate AlPO4-5, from room temperature to 850 °C, carried out by in situ synchrotron X-ray powder diffraction experiments. No phase transitions were observed in the investigated T range. Due to the very low interactions among framework and water molecules, dehydration is already complete at 152 °C. It occurs in two main T ranges, one between 60 and 80 °C and the second one between 90 and 120 °C. During these two stages, the cell volume tends to increase to facilitate the water release. Overall, across the full explored T range, the cell volume increase is only 0.84%, indicating that AlPO4-5 is one of the most rigid zeolite frameworks studied to date. Specifically, after complete dehydration at 200 °C, AlPO4-5 undergoes a negative thermal expansion as a consequence of the decrease in both a and c cell parameters. The expansion coefficients for V, a and c cell parameters, in the 152–850 °C range, are αV = −7.12 (10−6/K), αa = −2.5 (10−6/K), αc = −2.2 (10−6/K), respectively.
      Graphical abstract image

      PubDate: 2017-11-17T05:43:04Z
       
 
 
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