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Journal Cover Microporous and Mesoporous Materials
  [SJR: 1.243]   [H-I: 116]   [6 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1387-1811
   Published by Elsevier Homepage  [3041 journals]
  • Rational seed-directed synthesis of MSE-type zeolites using a simple
           organic structure-directing agent by extending the composite building unit
           hypothesis
    • Authors: Sibel Sogukkanli; Kenta Iyoki; Shanmugam P. Elangovan; Keiji Itabashi; Miku Takano; Zhendong Liu; Satoshi Inagaki; Toru Wakihara; Yoshihiro Kubota; Tatsuya Okubo
      Pages: 1 - 7
      Abstract: Publication date: June 2017
      Source:Microporous and Mesoporous Materials, Volume 245
      Author(s): Sibel Sogukkanli, Kenta Iyoki, Shanmugam P. Elangovan, Keiji Itabashi, Miku Takano, Zhendong Liu, Satoshi Inagaki, Toru Wakihara, Yoshihiro Kubota, Tatsuya Okubo
      Unlike previous reports stating that costly and bulky organic molecules are essential to form MSE-type zeolites, we report herein a simplified and efficient synthesis route to these multi-dimensional, large-pore zeolites by using tetraethylammonium hydroxide (TEAOH) as an organic structure-directing agent (OSDA). Rather than conventional methods, alternative synthesis pathways in which such OSDAs are replaced with inexpensive and simple molecules/cations are recently demanding. In order to select the OSDAs and determine the synthesis conditions from a huge “zeolite synthesis library,” we applied the “composite building unit hypothesis” which we have proposed for the seed-directed, OSDA-free synthesis methods. By applying this hypothesis, a clear relation was found among MSE, *BEA, and MOR framework types. According to this relation, TEAOH which is basically utilized for the industrial production of *BEA-type zeolite was determined to be used in a modified gel composition as an easily reachable and comparatively inexpensive OSDA. This novel approach allowed us to obtain pure solid products with high yields by consecutively applying aging and hydrothermal synthesis steps. The series of characterizations revealed that the features of obtained products were similar to those of conventional MCM-68 with relatively better microporosity characteristics. Remarkably, the “second-generation” products can be synthesized via this novel route by optimizing the aging time. Considering the overall results, this method is the most simplified and efficient synthesis route for MSE-type zeolites, and we believe that this approach can be further extended to the synthesis of other multi-dimensional, large-pore zeolites.
      Graphical abstract image

      PubDate: 2017-03-08T07:42:46Z
      DOI: 10.1016/j.micromeso.2017.02.073
      Issue No: Vol. 245 (2017)
       
  • Study of CO2 adsorption on iron oxide doped MCM-41
    • Authors: Kingkaew Chayakul Chanapattharapol; Somkiat Krachuamram; Sujittra Youngme
      Pages: 8 - 15
      Abstract: Publication date: June 2017
      Source:Microporous and Mesoporous Materials, Volume 245
      Author(s): Kingkaew Chayakul Chanapattharapol, Somkiat Krachuamram, Sujittra Youngme
      Carbon dioxide adsorption behaviors of iron oxide doped mesoporous silica (MCM-41) were investigated. The iron oxide doped on MCM-41 samples were prepared by impregnation method with iron concentrations of 0.10, 0.25, 0.50, 0.75 and 1.0 wt%. The XRD patterns indicate highly dispersed forms of iron oxide on MCM-41. The results from N2 adsorption-desorption showed that there was no difference in mesoporous structure upon the addition of iron oxide and that the morphology of doped adsorbent was slightly distorted from its original spherical shape. Adsorption isotherm indicated that modifying MCM-41 with iron oxide can increase CO2 adsorption with the best result being achieved with 0.50 wt%Fe/MCM-41. Good correlations between the adsorption extent and the surface area were observed. Interaction between CO2 and Fe atoms were studied by X-ray absorption near edge structure (XANES). XANES spectra indicated the transfer of metal d-electrons to CO2 π*-antibonding orbital giving rise to additional adsorption. Stronger bonding between CO2 and the adsorbent was indicated by the increase of the isosteric heat of adsorption.
      Graphical abstract image

      PubDate: 2017-03-08T07:42:46Z
      DOI: 10.1016/j.micromeso.2017.02.072
      Issue No: Vol. 245 (2017)
       
  • Effects of secondary mesoporosity and zeolite crystallinity on catalyst
           deactivation of ZSM-5 in propanal conversion
    • Authors: Youngsun Jun; Songhyun Lee; Kyungho Lee; Minkee Choi
      Pages: 16 - 23
      Abstract: Publication date: June 2017
      Source:Microporous and Mesoporous Materials, Volume 245
      Author(s): Youngsun Jun, Songhyun Lee, Kyungho Lee, Minkee Choi
      Cooperative effects of secondary mesoporosity and zeolite crystallinity on the deactivation of ZSM-5 were investigated during propanal conversion. Varied secondary mesoporosities were introduced into a commercial ZSM-5 by alkaline desilication using solutions with different NaOH concentrations (0.1–0.5 M). The results showed that the mesoporosity gradually increased with the concentration of NaOH, while the intrinsic zeolitic microporosity decreased. This indicated that the alkaline desilication for mesopore generation is a destructive technique that sacrifices the zeolite crystallinity. In propanal conversion, ZSM-5 showed a longer catalyst lifetime as the external surface area increased (or as the zeolite framework thickness decreased) in the mild desilication regime (NaOH concentration ≤ 0.3 M). The enhanced catalyst lifetime could be attributed to the facilitated diffusion of coke precursors out of the zeolite structure. However, when the zeolite crystallinity or microporosity of ZSM-5 was decreased too much from excessively severe alkaline treatments (NaOH concentration > 0.3 M), deactivation of the catalyst became again faster. The result indicates that the crystallinity or the microporosity of ZSM-5 is also important in suppressing coke formation. This is in line with earlier reports showing that coke formation itself is a shape-selective reaction and significantly inhibited in the constrained space of the unique 10-membered micropore channels of ZSM-5. The present results imply that the generation of large mesoporosity (enhancing the diffusion of coke precursors) while keeping the zeolite crystallinity intact (suppressing coke formation by shape-selectivity) is highly desirable for designing a zeolite catalyst with an enhanced catalyst lifetime.
      Graphical abstract image

      PubDate: 2017-03-08T07:42:46Z
      DOI: 10.1016/j.micromeso.2017.02.071
      Issue No: Vol. 245 (2017)
       
  • Hybrid porous carbon materials derived from composite of humic acid and
           graphene oxide
    • Authors: Y.M. Shulga; S.A. Baskakov; Y.V. Baskakova; A.S. Lobach; Y.M. Volfkovich; V.E. Sosenkin; N.Y. Shulga; Y.N. Parkhomenko; A. Michtchenko; Y. Kumar
      Pages: 24 - 30
      Abstract: Publication date: June 2017
      Source:Microporous and Mesoporous Materials, Volume 245
      Author(s): Y.M. Shulga, S.A. Baskakov, Y.V. Baskakova, A.S. Lobach, Y.M. Volfkovich, V.E. Sosenkin, N.Y. Shulga, Y.N. Parkhomenko, A. Michtchenko, Y. Kumar
      Two materials have been derived from a composite of humic acid and graphene oxide (HA-GO). First material was obtained by high-temperature carbonization of the HA-GO composite in an inert atmosphere, and second material was produced by reduction of the HA-GO composite with hydrazine hydrate. The results of comparative studies of the materials using IR, Raman and XPS spectroscopies are presented. In IR spectra, no absorption due to stretching of vibrations OH is observed for both the materials. The XPS spectra of humic acids and its composite show sufficiently high content of carbon atoms, which are bonded with oxygen atoms, the C1s peak in the XPS spectra of both the materials under study show asymmetry inherent of graphite material, which confirms the outcomes of IR and Raman studies. This could be attributed to high conductivity of the materials. It has also been established that specific surface area SBET is equal to 36.2 and 6.5 m2/g for thermally treated composite and chemically treated composites materials, respectively. However, the values of specific surface area SSCP, measured by the method of standard contact porosimetry with octane as a working liquid, is equal to 470 m2/g and 200 m2/g in the case of thermally treated composite and chemically treated composites materials, respectively.
      Graphical abstract image

      PubDate: 2017-03-08T07:42:46Z
      DOI: 10.1016/j.micromeso.2017.02.061
      Issue No: Vol. 245 (2017)
       
  • Preparation, characterization and catalytic performance of Ag-modified
           mesoporous TiO2 in low-temperature selective ammonia oxidation into
           nitrogen and water vapour
    • Authors: Magdalena Jabłońska; Wirawan Ciptonugroho; Kinga Góra-Marek; Mohammad G. Al-Shaal; Regina Palkovits
      Pages: 31 - 44
      Abstract: Publication date: June 2017
      Source:Microporous and Mesoporous Materials, Volume 245
      Author(s): Magdalena Jabłońska, Wirawan Ciptonugroho, Kinga Góra-Marek, Mohammad G. Al-Shaal, Regina Palkovits
      Mesoporous TiO2 was prepared by evaporation induced self-assembly (EISA) and used as a support for silver with loadings of 1.5 or 10 wt%, respectively. Silver deposited on commercial TiO2 (anatase) and γ-Al2O3 served as reference catalysts. The mesoporous TiO2 were calcined at 500, 600, 700 and 800 °C in order to obtain anatase and/or rutile phases. The materials were characterized with respect to structural (XRD, TEM, UV-vis-DRS) and textural parameters (N2 adsorption-desorption), acidic properties (NH3-TPD, FTIR studies), redox properties (H2-TPR), and were applied as catalysts for the selective ammonia oxidation into nitrogen and water vapour (NH3-SCO). The catalytic performance (activity and N2 selectivity) was favoured over (1.5 wt%)Ag-doped mesoporous TiO2 calcined at 600 °C. Thus, mesoporous TiO2 with the predominant anatase phase, as a support guaranteed the formation of easily reducible highly dispersed oxidized silver species. Furthermore, these species were converted into Ag0 and possibly Agn δ+ clusters through in situ H2-pretreatment of catalysts. While mainly metallic silver catalyzed the decomposition of N2O into N2 and surface oxygen species, leading to higher N2 selectivity in NH3-SCO.
      Graphical abstract image

      PubDate: 2017-03-08T07:42:46Z
      DOI: 10.1016/j.micromeso.2017.02.070
      Issue No: Vol. 245 (2017)
       
  • Distribution of open sites in Sn-Beta zeolite
    • Authors: Tyler R. Josephson; Glen R. Jenness; Dionisios G. Vlachos; Stavros Caratzoulas
      Pages: 45 - 50
      Abstract: Publication date: June 2017
      Source:Microporous and Mesoporous Materials, Volume 245
      Author(s): Tyler R. Josephson, Glen R. Jenness, Dionisios G. Vlachos, Stavros Caratzoulas
      A survey of the open site geometries in Sn-Beta has been completed. Comparing the relative energies of 144 distinct open site structures identifies both T9 and T1 sites as the most stable open sites. However, a key feature of these sites is that the Sn-O-Si bridge which is hydrolyzed is opposite the SnOH, rather than adjacent. This results in geometries in which the SiOH in the open site is significantly more acidic than a surface SiOH or a SiOH defect in the zeolite, as found in adsorption calculations of NH3, pyridine, and acetonitrile. Frequency shifts calculated for acetonitrile are consistent with experimental frequency shifts, and the proposed open site geometry suggests a new assignment for a peak observed experimentally by Harris et al. [1] and Otomo et al. [2] The stabilization of the open site silanol by the nearby Sn generates this unusual Brønsted acidity in the Sn-Beta open site, which highlights the need to consider new reaction mechanisms in the Sn-Beta literature.
      Graphical abstract image

      PubDate: 2017-03-08T07:42:46Z
      DOI: 10.1016/j.micromeso.2017.02.065
      Issue No: Vol. 245 (2017)
       
  • Functionalization of hierarchically porous silica monoliths with
           polyethyleneimine (PEI) for CO2 adsorption
    • Authors: Xingzhong Guo; Li Ding; Kazuyoshi Kanamori; Kazuki Nakanishi; Hui Yang
      Pages: 51 - 57
      Abstract: Publication date: June 2017
      Source:Microporous and Mesoporous Materials, Volume 245
      Author(s): Xingzhong Guo, Li Ding, Kazuyoshi Kanamori, Kazuki Nakanishi, Hui Yang
      A novel CO2 sorbent was prepared by modifying polyethyleneimine (PEI) on hierarchically porous silica (HPS) monoliths with well-defined macro-mesopores through wet impregnation method. HPS monoliths before and after functionalization were characterized by scanning electron microscopy (SEM), differential thermal analysis/thermogravimetry (DTA/TG), fourier transform infrared spectroscopy (FT-IR) and nitrogen adsorption/desorption analysis (BET), and the CO2 adsorption-regeneration properties of as-synthesized sorbents were investigated by thermogravimetric analysis (TG). The effects of loaded PEI amount as well as adsorption temperature and CO2 partial pressure on the CO2 adsorption performance of the as-prepared sorbents were also studied. The results showed that the porous structure of HPS-PEI sorbents was preserved after functionalization, while the specific surface area and pore volume decreased with increasing amount of amines to some extent. The use of PEI had a remarkable improvement on the CO2 adsorption capacity. With the increasing amount of PEI loaded, the CO2 adsorption capacity improved significantly. The highest CO2 adsorption capacity of 2.44 mmol (g sorbent)−1 was obtained at 75 °C in the CO2 partial pressure of 100 kPa for the HPS loaded with 60 wt% PEI. Adsorption/desorption cycles indicated that the PEI-modified HPS sorbents had a good stability and regeneration.
      Graphical abstract image

      PubDate: 2017-03-15T18:23:55Z
      DOI: 10.1016/j.micromeso.2017.02.076
      Issue No: Vol. 245 (2017)
       
  • Numerical evaluation of the diffusion enhancement in meso-microporous
           materials originating from mesopores
    • Authors: Xueyu Tian; Xianzhi Deng; Xiaojiang Tan; Xiaohong Yan
      Pages: 58 - 63
      Abstract: Publication date: June 2017
      Source:Microporous and Mesoporous Materials, Volume 245
      Author(s): Xueyu Tian, Xianzhi Deng, Xiaojiang Tan, Xiaohong Yan
      Six models of meso-microporous materials having both micropores and mesopores are numerically constructed. Effective diffusion coefficients for these models are predicted by the volume averaging method. Solute diffusion coefficient in mesopores is assumed to be much larger than that in micropores. Effects of equilibrium distribution constant, the ratio of diffusion coefficient in mesopores to that in microporous regions, mesopore shape and mesoporosity on the diffusion enhancement originating from mesopores are discussed. It is found that the diffusion enhancement decreases with the increasing equilibrium distribution constant, and increases with the increasing mesoporosity and the ratio of diffusion coefficient in mesopores to that in microporous regions. The influence of the mesopore shape on the diffusion enhancement is obvious when the solute equilibrium distribution constant is small, but the influence decreases with increasing equilibrium distribution constant. A prediction of the diffusion enhancement based on the effective medium theory agrees reasonably with current numerical results.
      Graphical abstract image

      PubDate: 2017-03-15T18:23:55Z
      DOI: 10.1016/j.micromeso.2017.02.067
      Issue No: Vol. 245 (2017)
       
  • Kaolin-based magnetic zeolites A and P as water softeners
    • Authors: Raquel de Andrade Bessa; Luelc de Sousa Costa; Cristiane Pinto Oliveira; Felipe Bohn; Ronaldo Ferreira do Nascimento; José Marcos Sasaki; Adonay Rodrigues Loiola
      Pages: 64 - 72
      Abstract: Publication date: June 2017
      Source:Microporous and Mesoporous Materials, Volume 245
      Author(s): Raquel de Andrade Bessa, Luelc de Sousa Costa, Cristiane Pinto Oliveira, Felipe Bohn, Ronaldo Ferreira do Nascimento, José Marcos Sasaki, Adonay Rodrigues Loiola
      In this work, we report an experimental investigation on the synthesis of zeolites A and P, using kaolin as the main SiO2 and Al2O3 sources, by hydrothermal route, as well as on the structural, spectroscopic and magnetic properties of the produced zeolite composites with magnetite nanoparticles. The zeolites were successfully synthesized and the characterization of the obtained materials was carried out considering different techniques, including X-ray diffraction (XRD), infrared vibrational spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), as well as measurements of the magnetization as a function of the temperature and applied magnetic field. XRD analysis confirmed zeolites A and P as main crystalline phases, with a low intensity peak regarding the presence of small quantities of quartz remaining from the unreacted clay. SEM showed the well-defined morphologies of zeolites and, in the composites, magnetite nanoparticles dispersed over their surface. The average size of the magnetite nanoparticles was ca. 50 nm as determined by TEM analyses. The magnetic characterization confirmed the ferrimagnetic behavior of the magnetite nanoparticles and of the composites, as well as verified that the magnetic properties of the nanoparticles are not affected by the zeolites in the composite formation. Thus, the results evidenced that high quality zeolite composites with magnetite nanoparticles can be reached by considering the employed low cost method, placing this route as an attractive alternative for water softening reaching removal levels of about 97% in the first application times.
      Graphical abstract image

      PubDate: 2017-03-15T18:23:55Z
      DOI: 10.1016/j.micromeso.2017.03.004
      Issue No: Vol. 245 (2017)
       
  • From diverse polycyclic aromatic molecules to interconnected graphene
           nanocapsules for supercapacitors
    • Authors: Xiaojun He; Xiaojing Li; Jingxian Wang; Hao Ma; Hao Zhang; Yuanyang Xie; Nan Xiao; Jieshan Qiu
      Pages: 73 - 81
      Abstract: Publication date: June 2017
      Source:Microporous and Mesoporous Materials, Volume 245
      Author(s): Xiaojun He, Xiaojing Li, Jingxian Wang, Hao Ma, Hao Zhang, Yuanyang Xie, Nan Xiao, Jieshan Qiu
      3D interconnected graphene nanocapsules (IGNCs) were prepared by a template strategy coupled with in-situ chemical activation technique via using diverse polycyclic aromatic molecules as building blocks for supercapacitors. Benefiting from the synergistic effects of nano-MgO-template and in-situ KOH activation, the 3D IGNCs feature seemingly incompatible advantages of conductive and porous properties, possessing interconnected thin networks for high electron conduction, short hierarchical pores for fast ion transport, and abundant accessible active sites for ion adsorption. The specific surface area, pore size and pore volume mainly depend on the mass of raw materials and the annealing temperatures. When evaluated as electrodes for supercapacitors, IGNCs exhibit remarkably enhanced electrochemical characteristics such as high capacitance, good rate performance and cycle stability. This work opens up a facile way for high-efficiency preparation of 3D IGNCs from diverse aromatic hydrocarbon sources for energy storage to substitute conventional porous carbons.
      Graphical abstract image

      PubDate: 2017-03-15T18:23:55Z
      DOI: 10.1016/j.micromeso.2017.02.078
      Issue No: Vol. 245 (2017)
       
  • Ammonium nitrate-enhanced microwave solution combustion fabrication of
           CuO/ZnO/Al2O3 nanocatalyst for fuel cell grade hydrogen supply
    • Authors: Hossein Ajamein; Mohammad Haghighi; Shervin Alaei; Shahab Minaei
      Pages: 82 - 93
      Abstract: Publication date: June 2017
      Source:Microporous and Mesoporous Materials, Volume 245
      Author(s): Hossein Ajamein, Mohammad Haghighi, Shervin Alaei, Shahab Minaei
      CuO/ZnO/Al2O3 nanocatalysts were synthesized by microwave assisted combustion synthesis method using modified fuels containing ammonium nitrate as combustion aid. Sorbitol, propylene glycol, glycerol, diethylene glycol and ethylene glycol were used as combustion fuels to study fuel effect in MWCS method. The prepared nanocatalysts have been characterized by XRD, FESEM, EDX, FTIR and surface area analysis, BET techniques. The results show that combustion fuel can alter structural properties of fabricated nanopowder such as crystallography, dispersion and size distribution which can improve catalytic performance of synthesized nanocatalyst. FESEM images revealed that ethylene glycol resulted in better catalytic performance, since it has homogenous morphology with smaller particle size, high dispersion of metal oxides with no agglomeration.
      Graphical abstract image

      PubDate: 2017-03-15T18:23:55Z
      DOI: 10.1016/j.micromeso.2017.03.003
      Issue No: Vol. 245 (2017)
       
  • Control of average particle size of carbon aerogel supported platinum
           nanoparticles by supercritical deposition
    • Authors: Şansım Bengisu Barım; Ayşe Bayrakçeken; Selmi Erim Bozbağ; Lichun Zhang; Rıza Kızılel; Mark Aindow; Can Erkey
      Pages: 94 - 103
      Abstract: Publication date: June 2017
      Source:Microporous and Mesoporous Materials, Volume 245
      Author(s): Şansım Bengisu Barım, Ayşe Bayrakçeken, Selmi Erim Bozbağ, Lichun Zhang, Rıza Kızılel, Mark Aindow, Can Erkey
      Supercritical deposition was used to synthesize Pt/carbon aerogel (Pt/CA) electrocatalysts. CAs with average pore diameters of 6, 8 and 19 nm (CA6, CA8 and CA19, respectively) were synthesized and impregnated with Pt(cod)me2 precursor using supercritical carbon dioxide followed by the thermal conversion of the Pt precursor into its metallic form under N2 atmosphere at various temperatures between 200 and 1000 °C. All of the prepared CAs have high surface areas with very sharp pore size distributions. XRD and TEM results show increased Pt particle size with increasing conversion temperature with a homogenous distribution of nanoparticles on the CA supports. Cyclic voltammetry was used to determine the effect of CA pore properties on electrocatalytic activity. At a conversion temperature of 400 °C, the highest and lowest electrochemical surface area values were obtained for Pt/CA19 and Pt/CA6 of (126 and 36 m2/g, respectively). Furthermore, Pt/CA19 showed good mass activity whereas Pt/CA6 and Pt/CA8 had lower activity values towards the Oxygen Reduction Reaction (ORR). The mass activity values for Pt/CA19 increased with increasing conversion temperature, except for the sample converted at 1000 °C which exhibited the lowest mass activity. The specific activity increased significantly with the conversion temperature up to 600 °C which gave a value six times that obtained at 200 °C. At 800 °C, the specific activity decreased slightly, probably due to a change in the CA structure at this elevated conversion temperature. The Pt/CA19 sample converted at 600 °C exhibited the best performance with a mass activity of 0.1 A/mgPt and a specific activity of 0.24 mA/cm2.
      Graphical abstract image

      PubDate: 2017-03-15T18:23:55Z
      DOI: 10.1016/j.micromeso.2017.01.037
      Issue No: Vol. 245 (2017)
       
  • An integrated function system using metal nanoparticle@mesoporous
           silica@metal-organic framework hybrids
    • Authors: Takashi Ohhashi; Takaaki Tsuruoka; Kohei Inoue; Yohei Takashima; Satoshi Horike; Kensuke Akamatsu
      Pages: 104 - 108
      Abstract: Publication date: June 2017
      Source:Microporous and Mesoporous Materials, Volume 245
      Author(s): Takashi Ohhashi, Takaaki Tsuruoka, Kohei Inoue, Yohei Takashima, Satoshi Horike, Kensuke Akamatsu
      Multifunctional triple-compartment hybrids consisting of Au nanoparticle (NP)@mesoporous silica (mSiO2)@metal-organic framework (MOF) have been successfully synthesized via selective nucleation and growth on the surface of NP@mSiO2 nanostructures. Most importantly, these hybrids possess unique dual independent pores with different pore sizes based on mSiO2 and MOF for loading of larger organic molecules and sieving of smaller organic molecules. Through characterization of the pore properties of both porous materials, triple-compartment hybrids can be employed in sensing materials on the basis of the fluorescence properties of the doped fluorescent molecules within the mSiO2 phase and the molecular sieving effect of MOF. These hybrid nanostructures also show plasmonic properties due to the Au NPs.
      Graphical abstract image

      PubDate: 2017-03-15T18:23:55Z
      DOI: 10.1016/j.micromeso.2017.02.074
      Issue No: Vol. 245 (2017)
       
  • Synthesis of novel amine modified hollow mesoporous silica@Mg-Al layered
           double hydroxide composite and its application in CO2 adsorption
    • Authors: Muge Sari Yilmaz
      Pages: 109 - 117
      Abstract: Publication date: June 2017
      Source:Microporous and Mesoporous Materials, Volume 245
      Author(s): Muge Sari Yilmaz
      In this study, novel amine modified hollow mesoporous silica (HMS)@Mg-Al layered double hydroxide (LDH) composite was successfully prepared in order to evaluate its CO2 adsorption capacity. Pure and amine modified HMS composite, and HMS@Mg-Al LDH adsorbents were also prepared for the comparison of their CO2 adsorption capacities. The prepared adsorbents were characterized using X-ray diffraction (XRD), elemental analysis (EA), thermogravimetric analysis (TGA), N2 adsorption/desorption, Fourier transform infrared (FTIR) and transmission electron microscopy (TEM) techniques. CO2 adsorption performances of the adsorbents at different temperatures were determined using a TGA system. The amine modified HMS@Mg-Al LDH and the amine modified HMS showed maximum CO2 adsorption capacities of 1.28 and 1.57 mmol g−1, respectively, at 75 °C. Furthermore, compared to other adsorbents, the amine modified HMS@Mg-Al LDH composite had the highest adsorption capacity at 25 °C. The CO2 adsorption isotherms on all the adsorbents were measured using a volumetric method, and the CO2 isotherms were evaluated by applying the Langmuir and Freundlich models. The Langmuir model fit well with the amine modified samples, while the Freundlich model fit well with pure samples. The amine modified adsorbents exhibited stable adsorption performance throughout four consecutive adsorption/desorption cycles.
      Graphical abstract image

      PubDate: 2017-03-15T18:23:55Z
      DOI: 10.1016/j.micromeso.2017.02.077
      Issue No: Vol. 245 (2017)
       
  • Synthesis of molybdenum-incorporated mesoporous silicates by
           evaporation-induced self-assembly: Insights into surface oxide species and
           corresponding olefin metathesis activity
    • Authors: Anand Ramanathan; Jian-Feng Wu; Rajamanickam Maheswari; Yongfeng Hu; Bala Subramaniam
      Pages: 118 - 125
      Abstract: Publication date: June 2017
      Source:Microporous and Mesoporous Materials, Volume 245
      Author(s): Anand Ramanathan, Jian-Feng Wu, Rajamanickam Maheswari, Yongfeng Hu, Bala Subramaniam
      Molybdenum-incorporated mesoporous silicates with different Si/Mo ratios were synthesized via the Evaporation Induced Self-Assembly (EISA) method. SAXS and nitrogen physisorption results confirm the ordered mesoporosity. The BET surface area, pore volume and pore size distribution generally decrease with Mo loading while preserving the mesoporosity. Highly dispersed monomeric and oligomeric MoOx species (Mo6+ oxidation state) were evident from diffuse reflectance UV–Vis and XPS spectra. H2-TPR results confirm the existence of polymeric MoOx and bulk crystalline MoO3 species. At lower loadings, Mo exits in both tetrahedral and octahedral symmetry as established by Mo L3-edge XANES studies. Mo-EISA catalysts with highly dispersed isolated MoOx sites display stable activity for 2-butene + ethylene metathesis that is comparable to those reported for WO3/SiO2 catalysts.
      Graphical abstract image

      PubDate: 2017-03-15T18:23:55Z
      DOI: 10.1016/j.micromeso.2017.03.001
      Issue No: Vol. 245 (2017)
       
  • Evaluation of the parameters utilized for the aerosol-assisted synthesis
           of HKUST-1
    • Authors: Masaru Kubo; Teruaki Saito; Manabu Shimada
      Pages: 126 - 132
      Abstract: Publication date: June 2017
      Source:Microporous and Mesoporous Materials, Volume 245
      Author(s): Masaru Kubo, Teruaki Saito, Manabu Shimada
      In this study, HKUST-1 (Cu3(BTC)2; BTC3− = 1,3,5-benzenetricarboxylate) is synthesized by conventional batch synthesis (BS) and novel aerosol-assisted synthesis (AAS), and the effects of various synthesis conditions are investigated. AAS involves the spraying of an HKUST-1 precursor solution through a two-fluid nozzle and subsequent drying, which continuously generates spherical HKUST-1 nanoparticle agglomerates in less than 1 s. The effects of AAS parameters, such as temperature, precursor concentration, and retention time, on the morphology, yield, selectivity, and pore textural characteristics of products are discussed using copper nitrate as a metal precursor. Furthermore, the effects of various copper sources and pH on the textural characteristics are examined by BS and AAS. At low concentration and high pH, the products obtained by AAS have a higher BET surface area (>1300 m2/g) than those obtained by BS (1200 m2/g).
      Graphical abstract image

      PubDate: 2017-03-15T18:23:55Z
      DOI: 10.1016/j.micromeso.2017.03.007
      Issue No: Vol. 245 (2017)
       
  • Removal of Fe from fly ash by carbon thermal reduction
    • Authors: Minghua Wang; Hui Zhao; Yan Liu; Chuiyu Kong; Amin Yang; Jingyu Li
      Pages: 133 - 137
      Abstract: Publication date: June 2017
      Source:Microporous and Mesoporous Materials, Volume 245
      Author(s): Minghua Wang, Hui Zhao, Yan Liu, Chuiyu Kong, Amin Yang, Jingyu Li
      Main chemical compositions of fly ash is SiO2 and Al2O3, which are also main chemical components of zeolite. Therefore, fly ash can be used to prepare zeolite after removing impurities such as Fe. Previous studies have only used the methods of magnetic separation and acid leaching to remove impurities, which can not wipe out the impurities thoroughly, especially Fe impurities. In the paper, carbon thermal method is used to reduce hematite, and then low valence Fe is removed by magnetic separation and acid leaching. The experimental results derived from XRF, XRD, SEM/EDS analysis show that the total iron content of the fly ash is reduced to be 0.49% from 4.62%, the CaO content is reduced to be 2.08% from 9.61% after 1 pretreatment cycle. The raw material requirements for the preparation of zeolite are preliminarily achieved.
      Graphical abstract image

      PubDate: 2017-03-15T18:23:55Z
      DOI: 10.1016/j.micromeso.2017.02.068
      Issue No: Vol. 245 (2017)
       
  • Development of HZSM-12 zeolite for catalytic degradation of high-density
           polyethylene
    • Authors: Antonio O.S. Silva; Marcelo J.B. Souza; Anne M.G. Pedrosa; Ana C.F. Coriolano; Valter J. Fernandes; Antonio S. Araujo
      Pages: 1 - 6
      Abstract: Publication date: 15 May 2017
      Source:Microporous and Mesoporous Materials, Volume 244
      Author(s): Antonio O.S. Silva, Marcelo J.B. Souza, Anne M.G. Pedrosa, Ana C.F. Coriolano, Valter J. Fernandes, Antonio S. Araujo
      The catalytic degradation of high density polyethylene (HDPE) was studied in the presence of HZSM-12 zeolites with different Si/Al ratio, by thermogravimetry and pyrolysis coupled to gas chromatography and mass spectrometry. The NaZSM-12 zeolite was synthesized by the hydrothermal method using methyltriethylammonium chloride as template. The HZSM-5 was obtained by ion exchange of NaZSM-12 with ammonium chloride, drying and subsequent calcination. The materials characterization were carried out by chemical analysis, X-ray diffraction, scanning electron microscopy, BET measurements and acidity by n-butylamine adsorption. The obtained HZSM-12 zeolites were physically mixed with HDPE in the proportion of 50%wt and submitted to thermogravimetric analyses at heating rates of 2.5; 5; 10 and 20 °C min−1. The addition of HZSM-12 to HDPE produced a decreasing in the temperature of polymer degradation, which was proportional to the zeolite acidity. The activation energy (Ea) for the process was determined from the non-isothermal model-free kinetic model proposed by Vyazovkin. The Ea decreases linearly with the concentration of acid sites on the HZSM-12 materials. From the pyrolysis data, the obtained products were typically light gases (C2-C3); liquid petroleum gases (C4-C5); and gasoline (C6-C10). This results suggest that acid zeolites are excellent materials for obtaining alternative fuels from catalytic recycling of plastics.
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      PubDate: 2017-02-21T18:08:04Z
      DOI: 10.1016/j.micromeso.2017.02.049
      Issue No: Vol. 244 (2017)
       
  • Release of full catalytic capacity of desilicated ZSM-5 in MTH reaction:
           Al migration along mesopore introduction and post engineering
    • Authors: Mingrui Li; Yong Huang; Chao Ju; Yunming Fang
      Pages: 7 - 14
      Abstract: Publication date: 15 May 2017
      Source:Microporous and Mesoporous Materials, Volume 244
      Author(s): Mingrui Li, Yong Huang, Chao Ju, Yunming Fang
      Alkali-treatment is an effective method for improving ZSM-5 lifetime in methanol to hydrocarbon (MTH) reaction. In this paper, the effect of alkali-treatment on framework Al migration in ZSM-5 was firstly studied by 27Al 2D MQMAS NMR experiment. The result clearly demonstrates that part of framework Al in ZSM-5 zeolite is migrated into extra-framework position along with the mesopore introduction. Such Al migration is the reason of Lewis acidity formation in zeolite during alkali-treatment. Lewis acidity, together with internal hydroxyl group, partly neutralizes the benefit of mesopore introduction in MTH reaction. Post-treatment of mesoporous ZSM-5 sample in FeF3/NH4HF2 can selectively diminish the Lewis acidity and internal hydroxyl group. The improvement of catalyst lifetime by such post-treatment clearly proves the negative effects of Lewis acidity and internal hydroxyl group in MTH reaction, and the benefits of mesopore in MTH reaction is potentially overlooked.
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      PubDate: 2017-02-21T18:08:04Z
      DOI: 10.1016/j.micromeso.2017.02.046
      Issue No: Vol. 244 (2017)
       
  • Dynamic cum batch adsorption of a vesicant CWA (2-chloroethyl ethyl
           sulfide) over synthetic erionite
    • Authors: Waheed Ahmad Khanday
      Pages: 15 - 20
      Abstract: Publication date: 15 May 2017
      Source:Microporous and Mesoporous Materials, Volume 244
      Author(s): Waheed Ahmad Khanday
      Erionite was synthesized under hydrothermal and static conditions and was characterized by Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and BET surface area measurement. The dynamic adsorption experiments were carried out on Temperature programed desorption (TPD) plus Chemisorption system (Micrometrics ASAP 2920 unit). Adsorption was found to be high initially and it then decreases with increase in injected volume. In batch reactor it was found that adsorption increases with increase in contact time between 2-chloroethyl ethyl sulfide and erionite only up to around 12 h after which it remains almost constant. It is exhibited from the data that maximum adsorption capacity of erionite for 2-chloroethyl ethyl sulfide was 70.26 mg/g at 25 °C. Pseudo second order kinetics was found to describe adsorption process better than pseudo first order kinetics. Freundlich and Langmuir isotherms applied on the adsorption data reveal that data fitted best for Freundlich model. Desorption pattern was analyzed which shows two types of peaks, sharp peak representing desorption of physisorbed 2-chloroethyl ethyl sulfide and a broad representing desorption of strongly chemisorbed 2-chloroethyl ethyl sulfide. Further it was observed that the adsorbent can be recycled and reused again.
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      PubDate: 2017-02-21T18:08:04Z
      DOI: 10.1016/j.micromeso.2017.02.042
      Issue No: Vol. 244 (2017)
       
  • Modification of gas selective SAPO zeolites using imidazolium ionic liquid
           to develop polysulfone mixed matrix membrane for CO2 gas separation
    • Authors: N.N.R. Ahmad; C.P. Leo; A.W. Mohammad; A.L. Ahmad
      Pages: 21 - 30
      Abstract: Publication date: 15 May 2017
      Source:Microporous and Mesoporous Materials, Volume 244
      Author(s): N.N.R. Ahmad, C.P. Leo, A.W. Mohammad, A.L. Ahmad
      Ionic liquids (ILs) with high CO2 solubility and selectivity have been extensively studied in recent years to improve the performance of CO2 separation membranes. The progress in the development of supported IL membranes, polymerized IL membrane, polymer/IL gel membranes and membrane gas absorption using IL is limited by the high viscosity and price of ILs. In this work, the gas selective SAPO-34 zeolite was modified using [emim][TF2N] IL before the zeolites were incorporated into polysulfone (PSf) asymmetric membrane which was prepared by phase inversion. The main objective of this work is to study the effects of immersion duration on the IL-functionality of zeolite, membrane morphology and gas separation properties of PSf/SAPO-34 zeolite mixed matrix membrane. The incorporation of IL into the SAPO zeolite was confirmed by energy dispersive X-ray analysis. This analysis also proved the well dispersion of SAPO-34 particles with IL modification for 6 h due to the improved polymer/filler interface morphology as shown by scanning electron microscopy analysis. The gas separation test further revealed that the membrane containing SAPO-34 modified with IL for 6 h showed a great enhancement in both CO2/CH4 and CO2/N2 selectivity (approximately 486% and 232% respectively) over the unmodified mixed matrix membrane.
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      PubDate: 2017-02-28T15:47:56Z
      DOI: 10.1016/j.micromeso.2016.10.001
      Issue No: Vol. 244 (2017)
       
  • A comparative study of precursor effect on manganese post-synthetic
           incorporation into the T-sites of dealuminated β-zeolite
    • Authors: Naseem S. Hayek; Nishita S. Lucas; Christine Warwar Damouny; Oz M. Gazit
      Pages: 31 - 36
      Abstract: Publication date: 15 May 2017
      Source:Microporous and Mesoporous Materials, Volume 244
      Author(s): Naseem S. Hayek, Nishita S. Lucas, Christine Warwar Damouny, Oz M. Gazit
      Manganese sites on zeolites are known to be catalytically active for a range of chemical reactions. The work here describes the post-synthetic incorporation of manganese (Mn) into the vacant silanol nests of β-zeolite. We show that markedly different material properties are obtained when the Mn(NO3)2 precursor is used as opposed to the Mn(Ac)2 precursor. Our DRIFT and XRD results show that the Mn(NO3)2 does not promote the incorporation of the Mn into the vacant silanol nests. Rather we find, by XRD and HRSEM, that the Mn(NO3)2 leads to the formation of poorly dispersed 14 ± 1 nm MnO2 crystals on the external surface of the dealuminated β-zeolite. On the contrary, when Mn(Ac)2 is used the XRD and DRIFT results clearly show the almost complete incorporation of Mn into the silanol nests and a significant effect on the microporous structure. HRSEM, DR-UV-Vis, H2-TPR and N2-physisorption show that the use of Mn(Ac)2 produces highly dispersed extra-framework Mn2O3 and Mn3O4 species inside and outside the pores of the dealuminated zeolite, where as in the case of Mn(NO3)2 the pores maintain their original properties. The difference in behavior between the two precursors is correlated to the intrinsic properties of the respective precursor and its interactions with the underlying zeolite support.
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      PubDate: 2017-02-28T15:47:56Z
      DOI: 10.1016/j.micromeso.2017.02.037
      Issue No: Vol. 244 (2017)
       
  • Influences of surfactants on the structures and properties of
           organo-palygorskite in oil-based drilling fluids
    • Authors: Guanzheng Zhuang; Zepeng Zhang; Jiahua Gao; Xiangming Zhang; Libing Liao
      Pages: 37 - 46
      Abstract: Publication date: 15 May 2017
      Source:Microporous and Mesoporous Materials, Volume 244
      Author(s): Guanzheng Zhuang, Zepeng Zhang, Jiahua Gao, Xiangming Zhang, Libing Liao
      Organo-palygorskite (OPal) is a potential rheological additive in oil-based drilling fluids. This work aims to reveal the influences of surfactants on the structures and properties of OPal in oil-based drilling fluids. Firstly, palygorskite was organically modified by three quaternary ammonium salts with different lipophilicity. The crystal structures and morphologies of OPal samples were characterized by X-ray diffraction and scanning electron microscope. Organic surfactants coated on the surface of palygorskite. Gel volume tests were used to indicate the compatibility between OPal and oil. Viscosity tests were applied to characterize the gel strength and ability of gel formation. The contents of different components of OPal/oil fluids and OPal/oil gels were obtained by mass analysis. Optical microscopy testified the dispersity of OPal/oil fluids. X-Ray diffraction was also applied to characterize the gel structure of OPal/oil. Better lipophilicity of surfactants lead to better dispersity of OPal in oil. However, excellent dispersity of can't automatically contribute to high viscosity and gel strength. A little polarity is beneficial for promoting the rheological properties of oil-based drilling fluids. Temperature rising facilitates the disaggregation of OPal in oil, but high temperature may result in thermal decomposition of surfactants on the surface of palygorskite.
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      PubDate: 2017-02-28T15:47:56Z
      DOI: 10.1016/j.micromeso.2017.02.059
      Issue No: Vol. 244 (2017)
       
  • Exchanging noble and seminoble cations into zeolites by oxygen vacancy ion
           exchange (OVIE)
    • Authors: Gwang Myeong Lee; Nam Ho Heo; Karl Seff
      Pages: 47 - 49
      Abstract: Publication date: 15 May 2017
      Source:Microporous and Mesoporous Materials, Volume 244
      Author(s): Gwang Myeong Lee, Nam Ho Heo, Karl Seff
      It is proposed that cation exchanged zeolites can be prepared by reacting their decationized forms, e.g., (SiO2)n(Al2O3)m, n ≥ 2m, with noble or seminoble metals and oxygen or ozone. The resulting oxide ions would very exoergically occupy vacancies in the zeolite framework and the cations would go to conventional extraframework positions. The noble metals Rh, Pd, Ir, Pt, and Au and the seminoble metals Ru, Ag, Re, Os, Hg, and Bi are suggested. A sample reaction using decationized zeolite LTA would be: 6Pd + 3O2 + Si12Al12O42 → Pd6Si12Al12O48. Decationized zeolites can be prepared by heating zeolites, especially high-Al zeolites, in their H+ or NH4 + forms, causing them to lose framework oxygen atoms as H2O. The reactions may occur by simply heating a mixture of starting materials in flowing oxygen or ozone, e.g., 6Pd + 3O2 + (NH4)12Si12Al12O48.nH2O → Pd6Si12Al12O48 + 12NH3 + (6 + n)H2O. This method may be extended to other inorganic ion exchangers.
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      PubDate: 2017-02-28T15:47:56Z
      DOI: 10.1016/j.micromeso.2017.02.047
      Issue No: Vol. 244 (2017)
       
  • Exploring the potential of resorcinol-formaldehyde xerogels as thermal
           insulators
    • Authors: Natalia Rey-Raap; E.G. Calvo; J.A. Menéndez; A. Arenillas
      Pages: 50 - 54
      Abstract: Publication date: 15 May 2017
      Source:Microporous and Mesoporous Materials, Volume 244
      Author(s): Natalia Rey-Raap, E.G. Calvo, J.A. Menéndez, A. Arenillas
      The contribution to the total thermal conductivity of porous materials depends mainly on the operating conditions and on its type of porosity. Accordingly, the thermal insulating capacities of several resorcinol-formaldehyde (RF) xerogels synthesized by microwave heating were investigated. First, the operating conditions were optimized, since the thermal conductivity measurements were to be performed both before and after the degassing of the organic xerogels and with various particle sizes, ranging from 3 mm to below 212 μm. Special attention was paid to the influence of the porous properties, particularly density and pore size, on the total thermal conductivity. A minimum thermal conductivity value of 0.035 W m−1 K−1 was obtained for an organic xerogel with a bulk density of 0.248 g cm−3 and a mean pore size of 144 nm. The results obtained suggest that RF xerogels would be highly suitable candidates for thermal insulation applications as their thermal conductivity values are comparable to those of commercial materials, such as expanded polystyrene (0.034 W m−1 K−1).
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      PubDate: 2017-02-28T15:47:56Z
      DOI: 10.1016/j.micromeso.2017.02.044
      Issue No: Vol. 244 (2017)
       
  • Adsorption of cesium on silica gel containing embedded phosphotungstic
           acid
    • Authors: Kenneth Seaton; Iuliia Little; Cameron Tate; Ray Mohseni; Marina Roginskaya; Volodymyr Povazhniy; Aleksey Vasiliev
      Pages: 55 - 66
      Abstract: Publication date: 15 May 2017
      Source:Microporous and Mesoporous Materials, Volume 244
      Author(s): Kenneth Seaton, Iuliia Little, Cameron Tate, Ray Mohseni, Marina Roginskaya, Volodymyr Povazhniy, Aleksey Vasiliev
      Mesoporous silica gel containing embedded phosphotungstic acid (PTA) was synthesized by sol-gel co-condensation of tetraethoxysilane with PTA in acidic media. The obtained material had high BET surface area and pore volume. A characteristic band of the Keggin structure of PTA was present in its FT-IR spectrum while its XRD patterns were absent. This proved the embedding of PTA on a sub-molecular level. The material demonstrated high adsorption capacity of Cs. Unexpectedly, porosity of the adsorbent increased after substitution of most protons by cesium cations. Cation exchange also favored agglomeration of the material particles. Kinetic studies showed that the adsorption data correlates strongly with the pseudo-second order model. The adsorbent had two types of adsorption sites: heteropolyacid anions and silanol groups. However, adsorption on silanol groups was very sensitive to the temperature. At the increased temperature, the nature of adsorption fit the Langmuir model extremely well. The obtained results can be used in the development of an effective adsorbent for clean-up of water contaminated by radioactive cesium-137.
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      PubDate: 2017-02-28T15:47:56Z
      DOI: 10.1016/j.micromeso.2017.02.025
      Issue No: Vol. 244 (2017)
       
  • Acid treated mordenites as adsorbents of C2H4 and H2 gases
    • Authors: Burcu Erdoğan Alver; Fahri Esenli
      Pages: 67 - 73
      Abstract: Publication date: 15 May 2017
      Source:Microporous and Mesoporous Materials, Volume 244
      Author(s): Burcu Erdoğan Alver, Fahri Esenli
      In this study, a mordenite-rich tuff (M) from the Şile region (NW Turkey) was treated with HNO3 and H2SO4 at various concentrations (1.0, 3.0 and 5.0 M) at 80 °C for 3 h. The adsorption properties of ethylene (C2H4) and hydrogen (H2) on natural and that of acid forms were examined experimentally at 273 and 77 K and up to 100 kPa using volumetric instrument, respectively. All the samples were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), and nitrogen (N2) adsorption methods. Some differences on XRD pattern were signed in between natural and acid modified samples according to the intensity, sharpness and crystallite degree of mordenite peaks. C2H4 and H2 adsorption capacities of the original and acid treated mordenites were in the range of 0.762–0.876 mmol g−1and 1.373–1.672 mmol g−1 at 273 and 77 K, respectively. The increasing retention values of C2H4 and H2 after the acid treatments were analyzed in comparison with the structural changes.
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      PubDate: 2017-02-28T15:47:56Z
      DOI: 10.1016/j.micromeso.2017.02.039
      Issue No: Vol. 244 (2017)
       
  • Sodalite cages of EMT zeolite confined neutral molecular-like silver
           clusters
    • Authors: Biao Dong; Richard Retoux; Vincent de Waele; Sandro G. Chiodo; Tzonka Mineva; Julien Cardin; Svetlana Mintova
      Pages: 74 - 82
      Abstract: Publication date: 15 May 2017
      Source:Microporous and Mesoporous Materials, Volume 244
      Author(s): Biao Dong, Richard Retoux, Vincent de Waele, Sandro G. Chiodo, Tzonka Mineva, Julien Cardin, Svetlana Mintova
      Stable luminescent silver clusters in nanosized EMT zeolite suspension were prepared and directly observed with high-resolution transmission electron microscopy (HRTEM). The luminescence of the Ag clusters remains stable in time due to their stabilization within the sodalite cages (0.7 nm) of the EMT zeolite nanocrystals. In addition to the experimental results, the first principle Density Functional Theory (DFT) computations showed that hydrated neutral clusters up to octamer (Ag8) with a diameter of 0.47 nm were stabilized in the sodalite cages of the EMT zeolite, trough binding of silver atom(s) to the zeolite oxygen(s). The silver clusters exhibit molecular-like emission properties (lem = 395 nm and t1/2 ≤ 1 ns) that are in a good agreement with the HRTEM and DFT results. The stabilization of charge silver species in the form of weakly interacting dimer or trimer was observed too, which was based on the microsecond lifetime of the emission band measured at 545 nm. The high stability combined with the luminescence properties of silver clusters in the EMT zeolite nanocrystals will be of great advantage for applications such as bio imaging and bio sensing.
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      PubDate: 2017-02-28T15:47:56Z
      DOI: 10.1016/j.micromeso.2017.02.029
      Issue No: Vol. 244 (2017)
       
  • On the synthesis and performance of hierarchical nanoporous TS-1 catalysts
    • Authors: Abdul-Lateef Adedigba; Gopinathan Sankar; C. Richard A. Catlow; Yonghua Du; Shibo Xi; Armando Borgna
      Pages: 83 - 92
      Abstract: Publication date: 15 May 2017
      Source:Microporous and Mesoporous Materials, Volume 244
      Author(s): Abdul-Lateef Adedigba, Gopinathan Sankar, C. Richard A. Catlow, Yonghua Du, Shibo Xi, Armando Borgna
      Hierarchical TS-1 zeolite was successfully prepared using chitosan as a sacrificial template. The X-ray diffraction showed that the presence of chitosan with the synthesis precursor had no deleterious effect on the crystallinity and phase purity of this zeolite. X-ray absorption spectroscopy at the Ti K-edge, FTIR and Raman spectroscopies revealed the titanium ions in the zeolite structure have predominantly tetrahedral coordination. However, it appears that the higher chitosan content in the synthesis gel imparted some hydrophilic character to the TS-1 system. Furthermore, the technique adopted for the preparation of the synthesis gel – e.g partially dried or fully dried – appears to affect the amount of framework titanium in the zeolite structure. The calcined form of the chitosan templated TS-1 zeolites exhibited higher cyclohexene conversion compared to the TS-1 material synthesised without this template, but these catalysts showed lower selectivity for cyclohexene epoxide.
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      PubDate: 2017-02-28T15:47:56Z
      DOI: 10.1016/j.micromeso.2017.02.048
      Issue No: Vol. 244 (2017)
       
  • The effect of H2O/SiO2 ratio in precursor solution on the crystal size and
           morphology of zeolite ZSM-5
    • Authors: Kseniya A. Sashkina; Zhiye Qi; Wei Wu; Artem B. Ayupov; Anton I. Lysikov; Ekaterina V. Parkhomchuk
      Pages: 93 - 100
      Abstract: Publication date: 15 May 2017
      Source:Microporous and Mesoporous Materials, Volume 244
      Author(s): Kseniya A. Sashkina, Zhiye Qi, Wei Wu, Artem B. Ayupov, Anton I. Lysikov, Ekaterina V. Parkhomchuk
      A series of zeolites ZSM-5 has been synthesized in hydrothermal conditions under various ratios of H2O/SiO2 ranging from 10 to 300. Materials have been characterized by X-ray diffraction, scanning and transmission electron microscopy, nitrogen adsorption measurements, X-ray fluorescence spectrometry, inductively coupled plasma optical emission spectrometry and temperature-programmed desorption of ammonia. The effect of H2O/SiO2 ratio in precursor solution on ZSM-5 product yield, crystallinity, crystal size, crystal size distribution, morphology, texture and acidity has been studied. The increase of H2O/SiO2 ratio in precursor solution from 10 to 300 results in decreasing the average crystal size from 1250 to 180 nm, the higher H2O/SiO2 ratio, the wider crystal size distribution. Aggregate-like mesoporous/hollow ellipsoid crystals and smooth pill-shaped crystals have been produced from precursor solutions with H2O/SiO2 = 25–100 and H2O/SiO2 = 10; 300, respectively. The average size of domains forming aggregate-like crystals is 40−50 nm. The specific acidity of ZSM-5 samples, synthesized from precursor solutions with different H2O/SiO2 molar ratios and the same Si/Al, has a trend to decrease along with the average crystal size increase.
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      PubDate: 2017-02-28T15:47:56Z
      DOI: 10.1016/j.micromeso.2017.02.060
      Issue No: Vol. 244 (2017)
       
  • Electrodeposited Nickel Cobalt Manganese based mixed sulfide nanosheets
           for high performance supercapacitor application
    • Authors: Surjit Sahoo; Rajat Mondal; Dattatray J. Late; Chandra Sekhar Rout
      Pages: 101 - 108
      Abstract: Publication date: 15 May 2017
      Source:Microporous and Mesoporous Materials, Volume 244
      Author(s): Surjit Sahoo, Rajat Mondal, Dattatray J. Late, Chandra Sekhar Rout
      Porous multi component Nickel Cobalt Manganese Sulfide (NCMS) nanosheets have been grown on Ni foam by cathodic electrodeposition method. The as-prepared NCMS nanosheets sample is used as an electrode material for supercapacitor application due to its large electrochemically active surface and high porosity structure. Moreover, NCMS nanosheets have good electrical and mechanical connections to the conductive Ni foam to achieve enhanced reaction kinetics with improved electrode integrity. The NCMS nanosheets exhibit an ultrahigh specific capacitance of 2717 F/g at a current density of 1 A/g with excellent cyclic stability and energy density of 94.07 Wh/kg. The electrodeposited NCMS nanosheets with extraordinary electrochemical performance enable the novel electrodes to hold great potential for high efficient energy storage systems.
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      PubDate: 2017-02-28T15:47:56Z
      DOI: 10.1016/j.micromeso.2017.02.043
      Issue No: Vol. 244 (2017)
       
  • Natrolites with different Fe2+/Fe3+ cation ratios
    • Authors: Yongmoon Lee; Thomas Vogt; Yongjae Lee
      Pages: 109 - 118
      Abstract: Publication date: 15 May 2017
      Source:Microporous and Mesoporous Materials, Volume 244
      Author(s): Yongmoon Lee, Thomas Vogt, Yongjae Lee
      We report the synthesis and structural characterization of two iron-exchanged natrolites, Fe2+ 4.0Fe3+ 2.7Al16Si24O80·29(1)H2O (Fe-NAT4951) and Fe2+ 6.4Fe3+ 1.1Al16Si24O80·24H2O (Fe-NAT8119) at different pressures and temperatures using ambient, high-temperature and in-situ high-pressure synchrotron powder X-ray diffraction, Mössbauer spectroscopy and extended X-ray absorption fine structure (EXAFS). At ambient conditions, Fe-NAT4951 crystallizes in an orthorhombic structure with space group F dd2 whereas the structure of Fe-NAT8119 is monoclinic with C c symmetry. Due to the presence of more H2O molecules in Fe-NAT4951 the channels are more circular as indicated by a T5O10 (T = Si,Al) chain rotation angle of 12.6(1)° compared to 20.4(1)° in Fe-NAT8119. The coordination number of the Fe2+ and Fe3+ cations in the channels of Fe-NAT4951 is 3 and 4, whereas Fe-NAT8119 has 7- and 4-fold coordination, respectively. The two materials behave differently under hydrostatic pressures: due to a discontinuous pressure-induced hydration the volume of Fe-NAT8119 expands by 14.1(1) % near 1.0(1) GPa, whereas the volume of Fe-NAT4951 gradually decreases with pressure. Under increasing temperature and as a result of abrupt dehydration, the unit cell volume of Fe-NAT4951 contracts by ca. 8.3(1) % near 125(1) °C whereas Fe-NAT8119 contracts only by ca. 5.0(1) % near 225(5) °C.
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      PubDate: 2017-02-28T15:47:56Z
      DOI: 10.1016/j.micromeso.2017.02.062
      Issue No: Vol. 244 (2017)
       
  • Controllable growth of defect-free zeolite protective layer on the surface
           of Pd membrane for chemical stability enhancement
    • Authors: Jiafeng Yu; Jixin Zhang; Chun Bao; Zhe Zhang; Hui Li; Hengyong Xu
      Pages: 119 - 126
      Abstract: Publication date: 15 May 2017
      Source:Microporous and Mesoporous Materials, Volume 244
      Author(s): Jiafeng Yu, Jixin Zhang, Chun Bao, Zhe Zhang, Hui Li, Hengyong Xu
      Pd membranes play a critical role in hydrogen purification due to excellent hydrogen permeability and selectivity. However, the poor chemical stability of Pd membranes when exposed to inclusion gases or organic reactants severely restricts their commercial applications. Herein, a novel strategy is developed to synthesize a thin and compact zeolite layer on the surface of Pd membrane which acts as an “armor” to protect it from being damaged by poisoning species. The results show that the zeolite membrane was NaA type and defect-free when using Si/Al ratio of 7.5 and silica sol as Si source after two-step hydrothermal synthesis. The variations of H2 permeance is monitored when Pd and zeolite-Pd composite membranes are exposed to 40% (ethanol/H2O) or 0.2% tetrahydrofuran (THF)/10% N2 in hydrogen atmosphere. Reactions between ethanol and water on Pd active sites are undetected, indicating the reactants are completely out of contact with Pd membrane in the presence of zeolite protective layer. Especially, compared to pure Pd membrane, almost 80% H2 permeance decline is constrained by the zeolite “armor” at 350 °C and W/E = 6. Moreover, the zeolite protective layer obviously enhances the chemical stability of Pd membrane by suppressing THF cracking and Pd active sites coverage.
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      PubDate: 2017-02-28T15:47:56Z
      DOI: 10.1016/j.micromeso.2017.02.063
      Issue No: Vol. 244 (2017)
       
  • Uptake of heavy metal ions from aqueous solutions by sorbents obtained
           from the spent ion exchange resins
    • Authors: D. Kołodyńska; J. Krukowska-Bąk; J. Kazmierczak-Razna; R. Pietrzak
      Pages: 127 - 136
      Abstract: Publication date: 15 May 2017
      Source:Microporous and Mesoporous Materials, Volume 244
      Author(s): D. Kołodyńska, J. Krukowska-Bąk, J. Kazmierczak-Razna, R. Pietrzak
      Obtaining useful sorbents from spent materials is of great importance. The paper presents the results of tests determining the kinetic and adsorption parameters on the removal of heavy metal Cu(II), Cd(II), Co(II) and Pb(II) ions on the carbonaceous adsorbents W1 KPS, W2 KPS, D1 CC3 and D2 CC3 obtained from spent ion exchangers. Among others the sorption effects of contact time, initial concentration, solution pH, influence of interfering ions were studied. W1 KPS obtained by the microwave heating exhibits a higher affinity for heavy metal ions than W2 KPS. However, for the sorbent obtained in the resistance furnace higher values of the sorption capacity were obtained for D2 CC3 rather than D1 CC3. It was found that the sorption capacity increases with the increasing initial concentration of the solution and phase contact time. The maximum pH adsorption was found at pH 5.0. A better fit of the kinetic data from the experimental one was presented using the pseudo second order model. In this paper, desorption using acidic desorbing agents was also examined. The results show that 2 M HNO3 is the most effective desorbing agent. Carbonaceous sorbents were characterized using elemental analysis, Fourier transform infrared spectroscopy and point of zero charge measurements. Differential scanning calorimetry analysis was also conducted.
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      PubDate: 2017-02-28T15:47:56Z
      DOI: 10.1016/j.micromeso.2017.02.040
      Issue No: Vol. 244 (2017)
       
  • Influence of structural, textural and chemical parameters of silver
           zeolites on the retention of methyl iodide
    • Authors: M. Chebbi; B. Azambre; L. Cantrel; M. Huvé; T. Albiol
      Pages: 137 - 150
      Abstract: Publication date: 15 May 2017
      Source:Microporous and Mesoporous Materials, Volume 244
      Author(s): M. Chebbi, B. Azambre, L. Cantrel, M. Huvé, T. Albiol
      An experimental screening of silver-exchanged zeolites towards the trapping of methyl iodide was carried out with the general aim of limiting as much as possible the iodine release in case of severe nuclear accident. For the first time, a systematic study was implemented in order to better understand the effects of some important parameters such as the zeolite structural type (FAU-X and Y, MOR, *BEA, MFI and FER) and chemical properties (namely the silver content and its speciation) on the adsorption behaviour. Characterization of 18 zeolitic sorbents, before or after iodine retention tests, was performed using elemental analyses, N2 porosimetry at −196 °C, XRD, DR-UV-Vis spectroscopy and TEM. The distribution of silver species, namely as isolated Ag+ cations or charged clusters in the internal porosity, and/or to a lesser extent as metallic nanoparticles, was found to depend mainly on the zeolite structural type and the Si/Al ratio and to a lesser extent on silver content. CH3I retention properties were evaluated from dynamic adsorption tests carried out at 100 °C. Quantitative exploitation of breakthrough curves showed that the silver faujasite zeolites of the Y type (Si/Al ratio = 2.5) with more than 15 wt% silver were the most efficient in order to achieve high adsorption capacities both at breakthrough and saturation. More generally, it is found that dispersed silver entities efficiently catalyze the dissociation of CH3I and the production of AgI precipitates.
      Graphical abstract image

      PubDate: 2017-02-28T15:47:56Z
      DOI: 10.1016/j.micromeso.2017.02.056
      Issue No: Vol. 244 (2017)
       
  • Synthesis, functionalization and evaluation of ethylene-bridged PMOs as
           adsorbents for sorption dehumidification and cooling systems
    • Authors: Camilo Sanchez; Felix Jeremias; Sebastian-Johannes Ernst; Stefan K. Henninger
      Pages: 151 - 157
      Abstract: Publication date: 15 May 2017
      Source:Microporous and Mesoporous Materials, Volume 244
      Author(s): Camilo Sanchez, Felix Jeremias, Sebastian-Johannes Ernst, Stefan K. Henninger
      Periodic mesoporous organosilica containing ethylene bridges have been synthesized and subsequently modified introducing sulfonate groups. The structural and physicochemical properties of the materials were characterized by nitrogen physisorption, FTIR spectroscopy and XRD. Their hydrophilic/hydrophobic behavior was studied by water sorption, while the hydrothermal stability of the sulfonated material and unmodified material were determined by multi-cycle stability tests. The sulfonated sample showed an improved hydrophilicity with a tripled water uptake at p/p 0 = 0.4. N2 and water sorption measurements before and after the cycle stability test revealed that the sulfonated sample lost capacity due to the reduced porosity. However, the overall hydrophilicity of the material even increased, which we ascribe to the hydroxylation of the organosilica surface. These findings indicate that PMOs containing ethylene bridges with a suitable hydrophilic functionality can be a promising adsorbent material for desiccant-based cooling system (DCS).
      Graphical abstract image

      PubDate: 2017-02-28T15:47:56Z
      DOI: 10.1016/j.micromeso.2017.02.058
      Issue No: Vol. 244 (2017)
       
  • Study on the oxidation transformation of hexamethyleneimine in a confined
           region of zeolites
    • Authors: Shaoqing Zhang; Miao Cui; Yifu Zhang; Yang Mu; Tianming Lv; Jiqi Zheng; Jing Zhao; Xiaoyu Liu; Changgong Meng
      Pages: 158 - 163
      Abstract: Publication date: 15 May 2017
      Source:Microporous and Mesoporous Materials, Volume 244
      Author(s): Shaoqing Zhang, Miao Cui, Yifu Zhang, Yang Mu, Tianming Lv, Jiqi Zheng, Jing Zhao, Xiaoyu Liu, Changgong Meng
      Two kinds of zeolites (mordenite and AlPO4-5, with MOR and AFI topology, respectively) have been synthesized using hexamethyleneimine (HMI) as structure directing agent. It is found that HMI is incorporated intact in its protonated form in MOR and AFI. Furthermore, the oxidation of HMI restricted in the two zeolites by H2O2 has been studied. Analysis of FT-IR, Raman spectra, TG/DTA, EA and 13C MAS NMR show that the restricted HMI molecules are changed into saturated hydrocarbons and some other amines in AFI, whereas unchanged in MOR. The adsorption tests illustrated that the as-synthesized samples and their oxidized products have high adsorption capacity for Ni(II). This work opens new opportunities for further research of molecular reactions on the inorganic hybrids, and provides a new idea for the application of SDAs present in molecular sieves.
      Graphical abstract image

      PubDate: 2017-03-08T07:42:46Z
      DOI: 10.1016/j.micromeso.2017.02.066
      Issue No: Vol. 244 (2017)
       
  • Effects of aluminum sources on synthesis and catalytic performance of
           b-oriented ZSM-5 coatings
    • Authors: Hong Liu; Guozhu Liu; Xiangwen Zhang; Dandan Zhao; Li Wang
      Pages: 164 - 170
      Abstract: Publication date: 15 May 2017
      Source:Microporous and Mesoporous Materials, Volume 244
      Author(s): Hong Liu, Guozhu Liu, Xiangwen Zhang, Dandan Zhao, Li Wang
      Highly b-oriented ZSM-5 zeolite coatings were synthesized on the inner surface of stainless steel tubes (2 mm i.d. and 400 mm length) precoated with a TiO2 sublayer by in situ crystallization. Four aluminum sources (aluminum nitrate, pseudo boehmite, aluminum isopropoxide and aluminum diacetate) were used and their effects on the structure and catalytic performance of the as-synthesized coatings have been investigated. The characterizations of XRD, SEM, 27Al MAS NMR and NH3−TPD revealed that the orientation and average size of crystals, continuity of zeolite layers, as well as their Si/Al ratio and acid properties, greatly affected by aluminum sources. The ZSM-5 layers synthesized with aluminum nitrate and pseudo boehmite (ANN-C and PB-C) had high b-orientation and almost full coverage, whereas those obtained with organic aluminum sources gave the opposite results. Compared with PB-C, ANN-C presented the small average size of crystals, low Si/Al ratio and large amount of acid sites. Catalytic cracking of n-dodecane at 500 °C and 4 MPa showed that ANN-C exhibited the most rapid cracking rate of n-dodecane and best stability. This is due to its highest b-orientation, which provides increased diffusion of n-dodecane and its cracking product molecules inside pore channels of ZSM-5 coatings.
      Graphical abstract image

      PubDate: 2017-03-08T07:42:46Z
      DOI: 10.1016/j.micromeso.2017.02.057
      Issue No: Vol. 244 (2017)
       
  • Role of decoration method of gold nanoparticles on the thermal and optical
           properties of mesoporous silica-Rhodamine 6G hybrids
    • Authors: Jisha John; Lincy Thomas; Achamma Kurian; V.P.N. Nampoori; Sajan D. George
      Pages: 171 - 179
      Abstract: Publication date: 15 May 2017
      Source:Microporous and Mesoporous Materials, Volume 244
      Author(s): Jisha John, Lincy Thomas, Achamma Kurian, V.P.N. Nampoori, Sajan D. George
      Nanotechnology offers the potential for creating new optical imaging agents with novel properties which has been used in molecular imaging and photothermal therapy. Mesoporous silica materials have attained great attention in industry due to its high thermal and chemical stability and non toxic behavior. The performance of mesoporous silica materials depends on composition, morphology and structure of made-up materials. The synthesis of mesoporous silica nanoparticles is highly sensitive because the size, morphology and pore structure changes with small change in procedure. Surface modification of mesoporous enables to incorporate metal nanoparticles in to its pores by co-condensation and post-synthesis method and hence an enhancement in optical and thermal properties of mesoporous silica nanoparticles. In the present work, we have synthesized gold nanoparticles incorporated mesoporous silica by three methods such as non functionalized, co-condensation and post-synthesis modification which is denoted as sample I, sample II and sample III. Thermal parameters such as thermal diffusivity and effusivity of the synthesized samples are measured by thermal lens and photoacoustic techniques respectively. From the values of thermal diffusivity and effusivity, thermal conductivity is estimated and a high value of thermal conductivity is obtained for sample II because of the proper encapsulation of gold nanoparticles in mesoporous silica. The influence of Rhodamine 6G concentrations on the thermal parameters of mesoporous silica is also studied which shows that thermal conductivity decreases with the addition of higher concentration of Rhodamine 6G due to the interface thermal resistance effects. In addition, we have investigated the influence of gold nanoparticle incorporated mesoporous silica on the emission properties of Rhodamine 6G and fluorescein dyes. Irrespective of dye concentration, due to plasmonic field effect and non aggregation of dye molecules, the fluorescence signal is enhanced for both dyes with the addition of gold incorporated mesoporous silica.
      Graphical abstract image

      PubDate: 2017-03-08T07:42:46Z
      DOI: 10.1016/j.micromeso.2017.02.050
      Issue No: Vol. 244 (2017)
       
  • Development of MIL-101(Cr)/GrO composites for adsorption heat pump
           applications
    • Authors: Eman Elsayed; Haiyan Wang; Paul A. Anderson; Raya Al-Dadah; Saad Mahmoud; Helena Navarro; Yulong Ding; James Bowen
      Pages: 180 - 191
      Abstract: Publication date: 15 May 2017
      Source:Microporous and Mesoporous Materials, Volume 244
      Author(s): Eman Elsayed, Haiyan Wang, Paul A. Anderson, Raya Al-Dadah, Saad Mahmoud, Helena Navarro, Yulong Ding, James Bowen
      Adsorption heat pumps can be used for generating heating, cooling, seasonal energy storage and water desalination applications. Metal-organic frameworks (MOFs) are hybrid porous materials with high surface area and superior adsorption characteristics compared to conventional adsorbents. MIL-101(Cr) has a large pore size with water vapour adsorption capacity up to 1.5 gH2O gads −1 and high cyclic stability, and thus has the potential to be used in adsorption heat pumps. This work investigates the enhancement of the thermal conductivity and water adsorption characteristics of MIL-101(Cr) using hydrophilic graphene oxide. Two methods have been used to develop MIL-101(Cr)/GrO composites. The first method was through the physical mixing of GrO and MIL-101(Cr) while the other was through incorporating the GrO during the synthesis process of MIL-101(Cr). The composites and neat MIL-101(Cr) were characterized in terms of their structure, water adsorption uptake, BET surface area, particle size, thermal gravimetric analysis, SEM images and thermal conductivity measurements. Results showed that introducing low amounts of GrO (2%) to the neat MIL-101(Cr) enhanced the water adsorption characteristics at high relative pressure but enhanced the heat transfer properties by 20–30% while using more than 2% of GrO reduced the water adsorption uptake but significantly enhanced the thermal conductivity by more than 2.5 times.
      Graphical abstract image

      PubDate: 2017-03-08T07:42:46Z
      DOI: 10.1016/j.micromeso.2017.02.020
      Issue No: Vol. 244 (2017)
       
  • Novel Ce-incorporated zeolite modified-carbon paste electrode for
           simultaneous trace electroanalysis of lead and cadmium
    • Authors: A. Kawde; A. Ismail; A.R. Al-Betar; O. Muraza
      Pages: 1 - 8
      Abstract: Publication date: 1 May 2017
      Source:Microporous and Mesoporous Materials, Volume 243
      Author(s): A. Kawde, A. Ismail, A.R. Al-Betar, O. Muraza
      Cerium incorporated zeolite-modified carbon paste electrode (Ce-ZCPME) was studied for the anodic stripping voltammetric detection of lead and cadmium ions. The modified electrode which was fabricated in-house by a prior hydrothermal synthesis of Ce-impregnated zeolite displayed satisfactory results compared to other reported electrodes. Deposition of the metal was achieved at a potential of −1.2 V (vs. Ag/AgCl) for 120 s followed by a square wave stripping scan from −1.6–0.0 V. Various experimental conditions which include nature of supporting electrolyte, pH, amplitude, frequency, deposition potential and deposition time were optimized prior to the analyses. The fabricated electrode revealed a linear behavior over the metal ion concentrations with a LOD (S/N = 3) of 0.07 ppb and 0.46 ppb for lead and cadmium detection, as well as a good reproducibility (RSD 2.23%) respectively. The fabricated electrode has the potential to be used in the analysis of environmental samples due to its lack of toxicity, ease of fabrication and relative inexpensiveness.
      Graphical abstract image

      PubDate: 2017-02-14T17:55:07Z
      DOI: 10.1016/j.micromeso.2017.02.008
      Issue No: Vol. 243 (2017)
       
  • Preparation and characterization of super-microporous alumina with
           crystalline structure
    • Authors: Yongfeng Li; Jiaojiao Su; Ruifeng Li
      Pages: 9 - 15
      Abstract: Publication date: 1 May 2017
      Source:Microporous and Mesoporous Materials, Volume 243
      Author(s): Yongfeng Li, Jiaojiao Su, Ruifeng Li
      Super-microporous alumina (pore size between 1 and 2 nm) with polycrystalline walls and high surface area (more than 650 m2/g) was synthesized successfully via an evaporation induced self-assembly (EISA) pathway using readily available and inexpensive nonionic surfactant fatty alcohol polyoxyethylene ether (AEO-7) as the template. N2 adsorption-desorption results showed that the obtained materials are super-microporous when removing the template at 400 °C, then if the calcination temperature increase from 600 °C to 1000 °C, a breakdown of the walls separating adjacent pores allows the transformation to mesopores (pore size > 2 nm). FTIR pyridine adsorption and NH3-TPD measurement suggested the presence of strong Lewis acid sites. Transmission electron microscopy (TEM) measurements indicated that the alumina possesses the disordered “wormhole-like” super-microporous structure with polycrystalline walls. Loaded with copper, the catalyst exhibited outstanding activity in the selective catalytic reduction of NO with methane and could achieve a NOx conversion 100% when the reaction temperature is over 600 °C.
      Graphical abstract image

      PubDate: 2017-02-14T17:55:07Z
      DOI: 10.1016/j.micromeso.2017.02.012
      Issue No: Vol. 243 (2017)
       
  • Temperature-dependent synthesis of Pd@ZIF-L catalysts via an assembly
           method
    • Authors: Hong Jiang; Songlin Xue; Yefei Liu; Weihong Xing; Rizhi Chen
      Pages: 16 - 21
      Abstract: Publication date: 1 May 2017
      Source:Microporous and Mesoporous Materials, Volume 243
      Author(s): Hong Jiang, Songlin Xue, Yefei Liu, Weihong Xing, Rizhi Chen
      The Pd@ZIF-L catalysts with uniform crosshair-star shape and a size of about 20 μm were synthesized by an assembly method, in which a two-dimensional layered zeolitic imidazolate framework-L (ZIF-L) was used as the support to immobilize Pd nanoparticles. Their catalytic activities were evaluated by the catalytic reduction of p-nitrophenol to p-aminophenol. The results highlight that the physical-chemical and catalytic properties of the Pd@ZIF-L catalysts are greatly affected by the synthesis temperature. The temperature variation can make the catalysts transform from two-dimensional flakes to zero-dimensional spheres. High temperature is beneficial for increasing Pd loading and encapsulating Pd nanoparticles within the ZIF-L matrix. However, under the temperature larger than 30 °C, the dense dia(Zn) structures are formed. Increasing Pd loading in the Pd@ZIF-L catalysts leads to a significantly higher p-nitrophenol conversion. The relative dense structure of the as-synthesized catalysts makes p-nitrophenol access the active centers difficultly and a lower catalytic activity is observed. These findings would aid the development of high-performance Pd@ZIF-L catalysts.
      Graphical abstract image

      PubDate: 2017-02-14T17:55:07Z
      DOI: 10.1016/j.micromeso.2017.02.007
      Issue No: Vol. 243 (2017)
       
  • Adsorption of As4O6 from flue gas by zeolites: Influence of pore structure
           and Al substitution
    • Authors: Xuesen Du; Jiyun Tang; Yanrong Chen; Xin Yang; Jingyu Ran; Li Zhang
      Pages: 22 - 27
      Abstract: Publication date: 1 May 2017
      Source:Microporous and Mesoporous Materials, Volume 243
      Author(s): Xuesen Du, Jiyun Tang, Yanrong Chen, Xin Yang, Jingyu Ran, Li Zhang
      Efficient storage of arsenic is very important to its capture in the flue gas of power plants. In this study, Grand Canonical Monte Carlo method and Density Functional Theory were used to study the adsorption of arsenic in zeolites with various Si/Al ratios and pore sizes. The results show that pores with diameter of 7 Å are optimal for As4O6 adsorption in zeolites. High porosity can also promote the adsorption of As4O6 in a specific amount of zeolite. Al substitutions are beneficial for As4O6 adsorption. Experiments were used to test the adsorption of As4O6 using H-ZSM-5 zeolites with different Si/Al ratios. The results show the same trend with the theoretical study. The influences of possible compositions in flue gas including SO2, NO, H2O, CO2 and N2 were also tested using Grand Canonical Monte Carlo method. SO2 and NO can cause notable drop of As4O6 adsorption.
      Graphical abstract image

      PubDate: 2017-02-14T17:55:07Z
      DOI: 10.1016/j.micromeso.2017.02.026
      Issue No: Vol. 243 (2017)
       
  • Preparation of binderless activated carbon monoliths from cocoa bean husk
    • Authors: M. Plaza-Recobert; G. Trautwein; M. Pérez-Cadenas; J. Alcañiz-Monge
      Pages: 28 - 38
      Abstract: Publication date: 1 May 2017
      Source:Microporous and Mesoporous Materials, Volume 243
      Author(s): M. Plaza-Recobert, G. Trautwein, M. Pérez-Cadenas, J. Alcañiz-Monge
      Binderless activated carbon monoliths were prepared from a new lignocellulosic precursor: cocoa bean husk. This study focussed on analysing the role of a lignocellusic-type precursor in the development of binderless carbon monoliths, and the characterisation of the porous texture and mechanical performance of the activated carbon monoliths. The results prove that an adequate combination of the macromolecular components of the cocoa bean husk (lignocellulosic molecules, gums, pectin and fats) together with a laminate macromolecular microstructure made it more suitable for obtaining binderless carbon monoliths, than other lignocellulosic precursors. In addition, the activation of these carbon monoliths gives activated carbon with a higher micropore volume and good mechanical performance.
      Graphical abstract image

      PubDate: 2017-02-14T17:55:07Z
      DOI: 10.1016/j.micromeso.2017.02.015
      Issue No: Vol. 243 (2017)
       
  • Influence of complexing agent on the removal of Pb(II) from aqueous
           solutions by modified mesoporous SiO2
    • Abstract: Publication date: 1 July 2017
      Source:Microporous and Mesoporous Materials, Volume 246
      Author(s): Yu Liu, Zimo Lou, Yue Sun, Xiaoxin Zhou, Shams Ali Baig, Xinhua Xu
      In this study, SiO2-EDTA was prepared by silanization reaction between N-(trimethoxysilylpropyl) ethylenediamine triacetic acid, trisodium salt (EDTA-silane) and hydroxyl groups for enhanced removal of Pb(II), Pb(II)-Cit (the clathrate generated by Pb(II) and trisodium citrate dehydrate(Cit)) and Pb(II)-EDTA(20%) from aqueous solutions. SiO2-EDTA composites were characterized using SEM, TEM, EDX-mapping, FTIR, XPS and TGA analyses. The influence of solution pH, initial concentration, contact time and co-existing interferents were also studied. Results demonstrated that the composite successfully adsorbed 147.52, 107.65 and 124.18 mg g−1 of Pb(II), Pb(II)-Cit, and Pb(II)-EDTA (20%), respectively with the initial Pb(II) concentration of 100 mg L−1. Kinetics study revealed that the adsorption rate was significantly high at the beginning and then reached to equilibrium within 1.0 h. Moreover, Pb(II) adsorption capacities were found to considerably affected by co-existing cations and not inhibited by natural organic matter (NOM). Characterization analyses confirmed that EDTA was successfully assembled on SiO2 which had been used as a supporting matrix due to its huge specific surface area. Findings from this study suggested that the present composite could be considered as a promising adsorbent for large scale treatment of wastewater containing elevated Pb(II) concentration.
      Graphical abstract image

      PubDate: 2017-03-20T18:34:43Z
       
  • 2D layered mesoporous MoO2/rGO composites for high performance anode
           materials in lithium-ion battery
    • Abstract: Publication date: 1 July 2017
      Source:Microporous and Mesoporous Materials, Volume 246
      Author(s): Shasha Wang, Baocang Liu, Guolei Zhi, Guangran Xu, Qin Wang, Jun Zhang
      Transition metal oxides are great promising anode materials with much higher theoretical electrochemical capacities for lithium ion battery compared with the commercialized carbon materials while serious capacity fading and poor cycle stability caused by large volume change and sluggish kinetics must be addressed for their practical application. Herein, we demonstrated a novel strategy to synthesize 2D layered mesoporous-MoO2/graphene (meso-MoO2/rGO) electrode materials using KIT-6/rGO as a template and ammonium molybdate as a precursor via a nanocasting method. By combining graphene with MoO2 and endowing it mesoporous structure, 2D layered meso-MoO2/rGO electrode materials are expected to show superior electrical conductivity, structured flexibility, and chemical stability, which may provide uninhibited conducting pathways for fast charge transfer and transport between oxide nanoparticles and graphene. In addition, mesoporous MoO2 is also anticipated to optimize Li+ transport in pore walls and fast electrolyte transport within highly ordered mesopores. As a result, meso-MoO2/rGO electrode materials possess an ordered mesoporous structure with a superior electrochemical performance. The electrochemical performances were examined using galvanostatical charge-discharge, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS) techniques. Benefiting from the combining effects of mesoporous MoO2 and 2D layered graphene, meso-MoO2/rGO electrode materials alleviate the volume effect and give an enhanced discharge and charge capacity and robust cycle stability. The meso-MoO2/rGO composite delivers the first discharge capacity of 1160.6 mA h g−1 and its reversible capacity is 801 mA h g−1 after 50 cycles, making it promising for potential uses as high performance anode materials in lithium-ion battery.
      Graphical abstract image

      PubDate: 2017-03-20T18:34:43Z
       
  • A new high performance polyamide as an effective additive for modification
           of antifouling properties and morphology of asymmetric PES blend
           ultrafiltration membranes
    • Abstract: Publication date: 1 July 2017
      Source:Microporous and Mesoporous Materials, Volume 246
      Author(s): Abbas Shockravi, Vahid Vatanpour, Zahra Najjar, Saedeh Bahadori, Ali Javadi
      Polyethersulfone (PES) ultrafiltration membrane with enhanced simultaneous permeability and fouling–resistance property was prepared using a new synthesized aromatic polyamide (PA-6) as an additive. A series of asymmetric membranes were prepared by adding different amounts of PA-6 to the casting solution using the phase inversion induced by immersion precipitation method. Attenuated total reflection-Fourier transform infrared spectra (ATR-FTIR) and water contact angle measurement confirmed the PA-6 enrichment at the membrane surface and increased the membrane hydrophilicity and wettability. The SEM images elucidated the effect of PA-6 addition on the PES membrane morphology by increasing the pore density. The results of filtration performance, which carried out by dead-end filtration of bovine serum albumin (BSA) solution showed that the permeability and fouling resistance property was improved by optimizing the PA-6 content. When the PA-6 content was 2 wt%, the permeability reached approximately 10 times over the pure PES membrane. In comparison to the blend membrane of PES and 2 wt% of polyvinyl pyrrolidone (PVP), the blend membrane of 2 wt% of PA-6 showed significant flux recovery ability. The rejection of all the blended membranes was approximately at high point over 95%. In addition, the results were compared with those obtained using PVP as a usual additive. Although the PVP blended membranes exhibited higher permeability, they showed lower antifouling properties. Finally, a membrane with 1 wt% PVP and 1 wt% PA-6 was prepared and showed the best performance regarding improved permeability and antifouling properties.
      Graphical abstract image

      PubDate: 2017-03-20T18:34:43Z
       
  • Flow dynamics of gases inside hydrotalcite-silica micropores
    • Abstract: Publication date: 1 July 2017
      Source:Microporous and Mesoporous Materials, Volume 246
      Author(s): A.D. Wiheeb, T.E. Mohammed, Z.A. Abdel-Rahman, M.R. Othman
      Maxwell-Stefan diffusion with single-site Langmuir isotherm was used to model the flow of gas inside micro pores of HT-Silica membrane. Coupled with Van't Hoff and Arrhenius equations, the diffusivity and energy contributed by the surface affinity and gas kinetics were quantified and evaluated. Results indicate that all of the four gases being studied were affected by the surface affinity to a significant extent. The surface affinity contributed 62% of the energy in the adsorption of CO2, 48% of the energy in the adsorption of CH4, 48% of the energy in the adsorption of N2 and 46% of the energy in the adsorption of H2. This explains the reason for the higher CO2 permeability despite the fact that the CO2 gas molecules are heavier than the other gas molecules being compared in the analysis.
      Graphical abstract image

      PubDate: 2017-03-20T18:34:43Z
       
 
 
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