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Journal Cover Microporous and Mesoporous Materials
  [SJR: 1.243]   [H-I: 116]   [9 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1387-1811
   Published by Elsevier Homepage  [3043 journals]
  • New evidence of the effect of the chemical structure of activated carbon
           on the activity to promote radical generation in an advanced oxidation
           process using hydrogen peroxide
    • Authors: Esther Vega; Héctor Valdés
      Pages: 1 - 8
      Abstract: Publication date: 15 March 2018
      Source:Microporous and Mesoporous Materials, Volume 259
      Author(s): Esther Vega, Héctor Valdés
      The influence of seven commercial activated carbons (ACs) to promote hydrogen peroxide decomposition and radical generation is assessed during four operating cycles. The amount of generated hydroxyl radicals is estimated from quenching experiments using methanol as a radical scavenger. The change in chemical surface composition of ACs upon contact with hydrogen peroxide after each operating cycle is measured by Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and by following the change in the value of the pH of the point of zero charge (pHPZC). Results reveal that when ACs are exposed to hydrogen peroxide for extended periods, their chemical surface composition is modified, reducing the capacity of these materials to promote hydrogen peroxide decomposition, and in turn decreasing the generation of hydroxyl radicals. Moreover, DRIFTS analyses show that ACs with an appreciable content of basic surface functionalities, such as chromene-type structures, would guarantee a continuous radical generation, reducing the loss of catalytic activity.
      Graphical abstract image

      PubDate: 2017-10-04T07:48:59Z
      DOI: 10.1016/j.micromeso.2017.09.018
      Issue No: Vol. 259 (2017)
       
  • Activated carbons from used motor oil as catalyst support for sustainable
           environmental protection
    • Authors: T. Tsoncheva; A. Mileva; S.P. Marinov; D. Paneva; N. Velinov; I. Spassova; A. Kosateva; D. Kovacheva; N. Petrov
      Pages: 9 - 16
      Abstract: Publication date: 15 March 2018
      Source:Microporous and Mesoporous Materials, Volume 259
      Author(s): T. Tsoncheva, A. Mileva, S.P. Marinov, D. Paneva, N. Velinov, I. Spassova, A. Kosateva, D. Kovacheva, N. Petrov
      Activated carbons obtained from used motor oil mixtures with furfural or coal tar pitch were prepared and tested as a host matrix of zinc and/or iron oxide nanoparticles. The obtained composites were characterized by nitrogen physisorption, Boehm method, XRD, UV–Vis, FTIR, Moessbauer spectroscopy and temperature programmed reduction. The catalytic behaviour of the samples was tested in methanol decomposition to syngas. The activated carbon obtained from motor oil and furfural was more amorphous and characterizes with higher acidic surface functionality, specific surface area and pore volume due to the simultaneous presence of micro- and mesopores. The modification procedure promoted development of “secondary” porosity which facilitated the formation of accessible to the reactant molecules finely dispersed and highly active metal oxide particles. Zinc ferrite modifications of both activated carbons exhibited higher catalytic activity, stability and good selectivity to syngas in comparison with the individual metal oxide ones.
      Graphical abstract image

      PubDate: 2017-10-04T07:48:59Z
      DOI: 10.1016/j.micromeso.2017.09.029
      Issue No: Vol. 259 (2017)
       
  • A novel porous flower-like HA/Ag nanocomposite: One pot preparation and
           excellent performances as both SERS nanosensor and catalyst
    • Authors: Xinna Gao; Yun Wu; Yiping Huang; Ying Yang; Anjian Xie; Yuhua Shen
      Pages: 1 - 7
      Abstract: Publication date: 1 March 2018
      Source:Microporous and Mesoporous Materials, Volume 258
      Author(s): Xinna Gao, Yun Wu, Yiping Huang, Ying Yang, Anjian Xie, Yuhua Shen
      Surface enhanced Raman scattering (SERS) as a powerful analytical tool provides strong enhancement factors, good reproducibility and stability, which has gained good application effect. But single-use or single functional SERS substrate has been limited to the needs of the people. Here, a porous flower-like Hydroxyapatite (HA)/Ag nanocomposite was prepared via one-pot sol-thermal method without any templates. The unique Raman enhancement effect of the HA/Ag nanocomposite as the SERS-active substrate was revealed by the rhodamine 6G (Rh6G) detection at a concentration as low as 1 × 10−10 M. In addition, the as-prepared porous nanocomposite as the catalyst for the reduction of p-nitrophenol (4-NP) can greatly shorten reaction time to 8 min (The rate constant k of the catalytic reaction is 0.426 min−1). Thus, the HA/Ag nanocomposite has wide applications in environmental detection and efficient catalytic degradation for organic pollutants.
      Graphical abstract image

      PubDate: 2017-09-14T06:50:54Z
      DOI: 10.1016/j.micromeso.2017.08.042
      Issue No: Vol. 258 (2017)
       
  • Quantifying nano-pore heterogeneity and anisotropy in gas shale by
           synchrotron radiation nano-CT
    • Authors: Yingfeng Sun; Yixin Zhao; Liang Yuan
      Pages: 8 - 16
      Abstract: Publication date: 1 March 2018
      Source:Microporous and Mesoporous Materials, Volume 258
      Author(s): Yingfeng Sun, Yixin Zhao, Liang Yuan
      As a tight reservoir, the majority of the pores in shale are nano pores. Compared to conventional reservoirs, the pore structure of shale presents strong heterogeneity and anisotropy. Quantitative characterization of nano-pore heterogeneity and anisotropy is of great significance for accurate assessment of gas reservoir capacity and the optimization of gas wells layout. In order to quantitatively characterize nano-pore heterogeneity and anisotropy in gas shale, experimental and images processing methods for gas shale nano-pore structure characterization by synchrotron radiation nano-CT were explored. The proposed method for quantitative characterization of nano-pore heterogeneity is independent of pore structure testing approach and sub-volumes number. Nano-pore anisotropy characteristics were quantitatively characterized by the eigenvalues and eigenvectors of permeability tensor, which was consistent with nano-pore geometrical morphology. Experimental and images processing methods in this paper can be references for other porous materials characterization by synchrotron radiation nano-CT. Methods for quantitative characterization of pores heterogeneity and anisotropy proposed in this paper are applicable for other porous media.
      Graphical abstract image

      PubDate: 2017-09-14T06:50:54Z
      DOI: 10.1016/j.micromeso.2017.08.049
      Issue No: Vol. 258 (2017)
       
  • Ru/hierarchical HZSM-5 zeolite as efficient bi-functional
           adsorbent/catalyst for bulky aromatic VOCs elimination
    • Authors: Yu Wang; Dengyao Yang; Shaozhong Li; Mengqiu Chen; Limin Guo; Jian Zhou
      Pages: 17 - 25
      Abstract: Publication date: 1 March 2018
      Source:Microporous and Mesoporous Materials, Volume 258
      Author(s): Yu Wang, Dengyao Yang, Shaozhong Li, Mengqiu Chen, Limin Guo, Jian Zhou
      This study is focused on the elimination of bulky aromatic VOCs by adsorption/combustion in humid conditions using Ru/hierarchical HZSM-5 zeolites as adsorbent and catalyst. Compared with Ru/conventional HZSM-5 zeolite, Ru/hierarchical HZSM-5 showed increased external surface and mesoporous volume, shortened diffusion length, and enhanced low-temperature reducibility. Adsorption experiments have led to the conclusion that Ru/hierarchical HZSM-5 zeolite was a very efficient adsorbent for the removal of bulky aromatic VOCs. And the catalytic activity of as-prepared composite in VOCs combustion had good correlations with their textural and composition characteristics. The value of turnover frequency (TOF) of Ru/hierarchical HZSM-5 was about twice, three and four times to that of Ru/conventional HZSM-5 toward toluene, o-xylene and TMB combustion, respectively, indicating a mo re significant performance promotion in catalyzing combustion of bulkier molecule. More importantly, Ru/hierarchical HZSM-5 was found to be suitable for the adsorption/combustion cycling process for bulky aromatic VOCs, good carbon balances being obtained for each cycle without the production of secondary pollutants.
      Graphical abstract image

      PubDate: 2017-09-14T06:50:54Z
      DOI: 10.1016/j.micromeso.2017.08.052
      Issue No: Vol. 258 (2017)
       
  • One-step and acid free synthesis of γ-Fe2O3/SBA-15 for enhanced
           arsenic removal
    • Authors: Xing Peng; Ying Zhao; Tianxue Yang; Yu Yang; Yonghai Jiang; Zhifei Ma; Xiaoguang Li; Jiaqi Hou; Beidou Xi; Hongliang Liu
      Pages: 26 - 32
      Abstract: Publication date: 1 March 2018
      Source:Microporous and Mesoporous Materials, Volume 258
      Author(s): Xing Peng, Ying Zhao, Tianxue Yang, Yu Yang, Yonghai Jiang, Zhifei Ma, Xiaoguang Li, Jiaqi Hou, Beidou Xi, Hongliang Liu
      A novel, one-step synthesis strategy is proposed to fabricate γ-Fe2O3/SBA-15 nanocomposite using triblock copolymer pluronic P123 as a structure directing agent without adding acids. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses suggested that iron was mainly present as γ-Fe2O3 in the composite. Transmission electron microscopy (TEM) measurement showed that this material had highly ordered hexagonal array of uniformed channels and N2 adsorption-desorption isotherms revealed that the surface area of this material was 983–1049 m2/g. Vibrating sample magnetometer (VSM) measurements explained that these materials possess magnetic properties (6.23 emu/g). Batch adsorption experiments showed that low pH was beneficial for arsenic removal by γ-Fe2O3/SBA-15. The presence of NO3 − and SO4 2- had no influence on the uptake of arsenic, however the existence of H2PO4 − and SiO3 2- showed negative effects on arsenic removal. After five adsorption–desorption cycles, the removal rate of arsenic maintained at larger than 70.5%. The arsenic adsorption was well fitted by a pseudo second-order kinetic model. The isotherm data agrees well with the Langmuir model better than the Freundlich model. This study suggests that γ-Fe2O3/SBA-15 is promising adsorbent for efficient removal of arsenic from groundwater.
      Graphical abstract image

      PubDate: 2017-09-14T06:50:54Z
      DOI: 10.1016/j.micromeso.2017.08.050
      Issue No: Vol. 258 (2017)
       
  • Effect of acidity in the removal-degradation of benzene in water catalyzed
           by Co-MCM-41 in medium containing hydrogen peroxide
    • Authors: Mirna Ferreira Farias; Yldeney Silva Domingos; Glauber José Turolla Fernandes; Francisco Laerte Castro; Valter José Fernandes; Maria José Fonseca Costa; Antonio Souza Araujo
      Pages: 33 - 40
      Abstract: Publication date: 1 March 2018
      Source:Microporous and Mesoporous Materials, Volume 258
      Author(s): Mirna Ferreira Farias, Yldeney Silva Domingos, Glauber José Turolla Fernandes, Francisco Laerte Castro, Valter José Fernandes, Maria José Fonseca Costa, Antonio Souza Araujo
      In this manuscript, MCM-41 and Co-MCM-41 were synthesized to evaluate the effect of the metal incorporated in the structure of the mesoporous material used in the benzene removal in aqueous medium containing hydrogen peroxide (H2O2). The decomposition of H2O2 in the medium containing MCM-41 and Co-MCM-41 was investigated. The techniques used to characterize these materials showed satisfactory results, proving that the synthesis was effective. The decomposition of hydrogen peroxide carried out in the ultraviolet/visible molecular absorption spectrophotometer revealed that the pH of the medium and the presence of cobalt influence its decomposition. In the reaction containing benzene + Co-MCM-41 + H2O2, it was possible to confirm this information, because there was practically no decomposition at pH = 1.5, 3.0 and 5.0, whereas decomposition was considerable at pH = 7.0 and 10.0 and all H2O2 was decomposed at pH = 12. Tests containing benzene + H2O2 + MCM-41 resulted in a higher removal of analytes in an alkaline medium. The last catalytic tests contained benzene + Co(II) + H2O2 in the aqueous reaction medium; compared to benzene + Co-MCM-41 + H2O2, it was found that the influence of Co-MCM-41 can be better viewed in pH = 10.0 and 12.0, because 82.1% of benzene was removed after 5 h.
      Graphical abstract image

      PubDate: 2017-09-19T19:12:28Z
      DOI: 10.1016/j.micromeso.2017.09.003
      Issue No: Vol. 258 (2017)
       
  • The effect of structure of mesoporous silica and niobiosilicate on
           incorporation and stability of modifiers introduced by the click reaction
           catalyzed by different copper salts
    • Authors: Katarzyna Stawicka; Klaudia Drazkiewicz; Maria Ziolek
      Pages: 41 - 54
      Abstract: Publication date: 1 March 2018
      Source:Microporous and Mesoporous Materials, Volume 258
      Author(s): Katarzyna Stawicka, Klaudia Drazkiewicz, Maria Ziolek
      The study was aimed at comparison of the stability and effectiveness of anchoring of the amine and sulfonic groups formed on mesoporous silica by the click reaction. The impact of silica dopant (niobium) and the structure of mesoporous silica (hexagonally ordered SBA-15 vs cellular foam MCF) on the properties and behavior of these surface groups was characterized in details. The modifiers stability was found to have a significant effect on the catalytic reactions in liquid phase. In order to increase the catalysts stability, the mesoporous silica and niobiosilicate were used as supports for ((3-azidopropyl)(triethoxy)silane) – AZPTES followed by the condensation with propargylamine or propargylsulfone by the click reaction performed in the presence of different copper salts used as catalysts of the process. The number of copper ions left in the material after the click reaction was also estimated.
      Graphical abstract image

      PubDate: 2017-09-19T19:12:28Z
      DOI: 10.1016/j.micromeso.2017.09.005
      Issue No: Vol. 258 (2017)
       
  • The fixation of carbon dioxide with epoxides catalyzed by cation-exchanged
           metal-organic framework
    • Authors: Xinlu Zhang; Zijuan Chen; Xiaoqian Yang; Meiyan Li; Chao Chen; Ning Zhang
      Pages: 55 - 61
      Abstract: Publication date: 1 March 2018
      Source:Microporous and Mesoporous Materials, Volume 258
      Author(s): Xinlu Zhang, Zijuan Chen, Xiaoqian Yang, Meiyan Li, Chao Chen, Ning Zhang
      Metal-organic frameworks (MOFs) possess high porosity and specific surface area and have been extensively applied in the capture and separation of CO2 from flue gas or natural gas. UTSA-16 is the second highest porous MOF for CO2 capture, which is attributed to its microporous structure with anatase type and the fact that the K+ species located in the channel can interact with CO2 molecule. Herein, a sequence of alkali metal cation-exchanged UTSA-16 (hereinafter denoted as M-UTSA-16, M = Li, Na, K, Rb, Cs) were prepared and evaluated for CO2 capture. The CO2 adsorption isotherms of M-UTSA-16 obtained at 273K and 298K showed that the adsorption capacity for CO2 decreased in the sequence of K+>Na+>Li+>Rb+>Cs+. The series of M-UTSA-16 were used as the catalyst for the transformation of CO2 and epoxide to cyclic carbonate in the absence of co-catalyst. Li-UTSA-16 exhibited the highest efficiency of catalytic activity compared with other M-UTSA-16. The result was inconsistent with the sequence of CO2 adsorption capacity. The further systematic investigation showed that the decreasing order of catalytic activities of M-UTSA-16 was in agreement with the sequence of increasing radius of the exchanged cations as well as the heat of adsorption for CO2 at lower pressure region.
      Graphical abstract image

      PubDate: 2017-09-19T19:12:28Z
      DOI: 10.1016/j.micromeso.2017.08.013
      Issue No: Vol. 258 (2017)
       
  • Alpha-pinene isomerization over Ti-SBA-15 catalysts obtained by the direct
           method: The influence of titanium content, temperature, catalyst amount
           and reaction time
    • Authors: Agnieszka Wróblewska; Piotr Miądlicki; Joanna Sreńscek-Nazzal; Marcin Sadłowski; Zvi C. Koren; Beata Michalkiewicz
      Pages: 72 - 82
      Abstract: Publication date: 1 March 2018
      Source:Microporous and Mesoporous Materials, Volume 258
      Author(s): Agnieszka Wróblewska, Piotr Miądlicki, Joanna Sreńscek-Nazzal, Marcin Sadłowski, Zvi C. Koren, Beata Michalkiewicz
      This work presents the studies on the isomerization of alpha-pinene in the presence of Ti-SBA-15 catalysts with different titanium contents: 0.75, 0.90, 1.10, and 3.10 wt%, as established by the EDX method, and 0.60, 0.76, 1.08, and 2.53 wt%, as measured by the ICP-AES method. These catalysts were prepared by the hydrothermal method and were characterized by the followed instrumental techniques: XRD, UV-Vis, FT-IR, SEM, ICP-AES, EDX, TEM, and AFM. Additionally, textural parameters were determined by N2 adsorption/desorption. Preliminary studies showed that the most active catalyst was the material prepared from the crystallization gel with the molar ratio of Si:Ti = 20:1. This catalyst was further used for the detailed studies on α-pinene isomerization according to the following parameters: temperature range of 20–200 °C, 0.5–20 wt% catalyst content, and reaction times from 15 min to 24 h. The optimal conditions for α-pinene isomerization were determined on the basis of its conversion and the selectivity of the produced camphene. This study also showed that the process of α-pinene isomerization is complex because subsequent reactions occurred during the process.
      Graphical abstract image

      PubDate: 2017-09-19T19:12:28Z
      DOI: 10.1016/j.micromeso.2017.09.007
      Issue No: Vol. 258 (2017)
       
  • V2O5 / nitrogen enriched mesoporous carbon spheres nanocomposite as
           supercapacitor electrode
    • Authors: Balakrishnan Saravanakumar; Kamatchi Kamaraj Purushothaman; Gopalan Muralidharan
      Pages: 83 - 94
      Abstract: Publication date: 1 March 2018
      Source:Microporous and Mesoporous Materials, Volume 258
      Author(s): Balakrishnan Saravanakumar, Kamatchi Kamaraj Purushothaman, Gopalan Muralidharan
      Developing vanadium based supercapacitor electrode materials with excellent rate capacity and cycling performance is still remaining as challenge towards their usefulness in advanced supercapacitor devices. In the present work, we have developed vanadium pentoxide (V2O5)/nitrogen containing mesoporous carbon spheres (n-MPC) nanocomposite without the use of expensive organic vanadium precursors and sophisticated instruments. The outcomes from different analytical investigations supporting well with the formation scheme of this hybrid material. Presence of n-MPC with V2O5 significantly enhances the conductivity and specific surface area. Commendably, V2O5/n-MPC electrode exhibit higher specific capacitance, good rate capacity and cyclic stability. This unique combination delivers specific capacitance as high as 487 Fg-1 at 0.5 Ag-1 and retains 410 Fg-1 at a higher current density of 10 Ag−1confirming its excellent rate performance. Further, this hybrid material show16% of capacitance fading up to 2000 charge-discharge cycles. Furthermore, a full cell supercapacitor assembled using V2O5/n-MPC electrode showing specific capacitance of 91 Fg-1 with an energy density of 12.8 WhKg−1. These attractive notable electrochemical features of V2O5/n-MPC nanocomposite confirm its usefulness towards advanced supercapacitor applications.
      Graphical abstract image

      PubDate: 2017-09-19T19:12:28Z
      DOI: 10.1016/j.micromeso.2017.09.010
      Issue No: Vol. 258 (2017)
       
  • Total and partial uptakes of multicomponent vapor-gas mixtures on 13X
           zeolite at 343K: Experimental and modeling study
    • Authors: Firas A. Abdul Kareem; Azmi Mohd Shariff; Sami Ullah; Lau Kok Keong; Nurhayati Mellon
      Pages: 95 - 113
      Abstract: Publication date: 1 March 2018
      Source:Microporous and Mesoporous Materials, Volume 258
      Author(s): Firas A. Abdul Kareem, Azmi Mohd Shariff, Sami Ullah, Lau Kok Keong, Nurhayati Mellon
      In this work, GERG2008 EoS embedded in volumetric-gravimetric system was developed to allocate multicomponent partial/individual components uptakes in the mixture. The refined arrangement may overlay the current theoretical anticipated outcomes and interchange it with experimental and more trustworthy selective adsorption outcomes. 13X zeolite was utilized as a solid adsorbent for binary and ternary CO2:CH4:H2O mixtures adsorption. Premixed and preloaded water vapor was studied at 343 K and up to 10 bar. Artificial neural network (ANN) modeling was engaged to predict binary and ternary mixtures. ANN results disclosed decent promise with experimental data. Besides, simulated formations utilizing ANN model replicated high consistency. The testified outcomes magnificently identified particular components behavior in ternary and higher multicomponent mixtures.
      Graphical abstract image

      PubDate: 2017-09-19T19:12:28Z
      DOI: 10.1016/j.micromeso.2017.09.004
      Issue No: Vol. 258 (2017)
       
  • Functionalized SBA-15 for controlled release of poorly soluble drug,
           Erythromycin
    • Authors: Soyeb Pathan; Priyanka Solanki; Anjali Patel
      Pages: 114 - 121
      Abstract: Publication date: 1 March 2018
      Source:Microporous and Mesoporous Materials, Volume 258
      Author(s): Soyeb Pathan, Priyanka Solanki, Anjali Patel
      SBA-15 was functionalized by 12-tungstophosphoric acid followed by loading of poorly water soluble drug, Erythromycin and Characterized by various physicochemical techniques such as TGA, FT-IR, Nitrogen adsorption-desorption, XRD and TEM. In-vitro controlled release studies of Erythromycin in Simulated Body Fluid were carried out under stirring as well as static conditions. In order to see the influence of inorganic moiety on release rate of drug, study was also carried out with Erythromycin loaded unfunctionalized SBA-15. A study on release mechanism and release kinetics using Higuchi model, Koresmeyer-Peppas model and Extended kinetic model shows that 12-tungstophosphoric acid has significant influence on the release rate of Erythromycin.
      Graphical abstract image

      PubDate: 2017-09-25T19:49:14Z
      DOI: 10.1016/j.micromeso.2017.09.012
      Issue No: Vol. 258 (2017)
       
  • Thermal transformations of (NH4, Cs)-clinoptilolite with compositions in
           between the end-members
    • Authors: Guido Cerri; Eleonora Sale; Antonio Brundu
      Pages: 122 - 130
      Abstract: Publication date: 1 March 2018
      Source:Microporous and Mesoporous Materials, Volume 258
      Author(s): Guido Cerri, Eleonora Sale, Antonio Brundu
      A powder containing about 90% of clinoptilolite in ammonium form, previously employed in a study concerning the thermal transformations of NH4-clinoptilolite, was used to prepare three samples with the following Cs+/NH4 + ratios: 0.51; 1.16; 5.00. These samples were subjected to thermal treatments of 2 h up to 1200 °C. Further treatments were executed at 1100 °C for 4, 8, 16 and 32 h. (NH4, Cs)-clinoptilolite underwent dehydration, de-ammoniation, dehydroxylation followed by amorphization and crystallization of new phases. Amorphization temperature increased, from 800 to 1000 °C, with the increase of cesium content. The composition of extraframework cations played the main role in determining the type and quantity of phases in the final products, as well as the kinetics of the crystallization. Basically, the thermal transformation of (NH4, Cs)-clinoptilolite can be described by two reactions producing: i) CsAlSi5O12 (CAS) + pollucite + glass, occurred in all samples; ii) mullite + cristobalite/tridymite + glass, occurred when Cs+/NH4 + ≤ 1.16. All samples showed the lowest residual glass content after 32 h at 1100 °C. The treatment of (NH4, Cs)-clinoptilolite with Cs+/NH4 + ≥ 1.16 allowed to confine all the cesium in crystalline phases, and the residual glass was below 15%. Conversely, when Cs+/NH4 + = 0.51 most of the cesium was in the prevalent (≈60%) amorphous phase.
      Graphical abstract image

      PubDate: 2017-09-25T19:49:14Z
      DOI: 10.1016/j.micromeso.2017.09.008
      Issue No: Vol. 258 (2017)
       
  • The efficiency of zeolite Y and surfactant-modified zeolite Y for removal
           of 2,4-dichlorophenoxyacetic acid and 1,1′-dimethyl-4,4′-bipyridinium
           ion
    • Authors: Yuwatida Pukcothanung; Theeranun Siritanon; Kunwadee Rangsriwatananon
      Pages: 131 - 140
      Abstract: Publication date: 1 March 2018
      Source:Microporous and Mesoporous Materials, Volume 258
      Author(s): Yuwatida Pukcothanung, Theeranun Siritanon, Kunwadee Rangsriwatananon
      The capacity of zeolite Y with a large Si/Al mole ratio and modified-zeolite Y, for removal of 2,4-dichlorophenoxyacetic acid (2,4-D) and 1,1′-dimethyl-4,4′-bipyridinium ion (paraquat ion; PQ2+) from aqueous solution was investigated. The surfaces of HY/NaY zeolites were modified using hexadecyltrimethylammonium (HDTMA) chloride and sodium dodecyl sulfated (SDS), and their physical characteristics were determined by X-ray diffractometry (XRD), FTIR, CHN/S analyzer, WD-XRF, TG-DTG, N2-adsorption-desorption isotherm, and NH3-TPD to confirm successful modification. Arrangement of surfactant in the admicelles was key for enhancing adsorption capacity of the zeolite. In the adsorption study, the concentration of surfactant and the pH were monitored and optimized. It was found that the adsorption capacity of PQ2+ increased with increasing SDS concentration. Conversely, high HDTMA density resulted in decreased adsorption capacity. For 2,4-D adsorption, adsorbents are more effective at greater HDTMA and SDS concentrations. The greatest adsorption values for 2,4-D and PQ2+ occurred at pH 3 and pH 11, respectively. Additionally, the water content of SDS-modified zeolite played an important role in the removal of pesticide. The equilibrium adsorption data can be fitted well using the Langmuir isotherm model and the adsorption kinetics follows a pseudo-second order model.
      Graphical abstract image

      PubDate: 2017-09-25T19:49:14Z
      DOI: 10.1016/j.micromeso.2017.08.035
      Issue No: Vol. 258 (2017)
       
  • Using Molecular Dynamics simulations for elucidation of molecular traffic
           in ordered crystalline microporous materials
    • Authors: Rajamani Krishna; Jasper M. van Baten
      Pages: 151 - 169
      Abstract: Publication date: 1 March 2018
      Source:Microporous and Mesoporous Materials, Volume 258
      Author(s): Rajamani Krishna, Jasper M. van Baten
      Robust models to describe mixture diffusion in ordered crystalline microporous materials such as zeolites, metal-organic frameworks (MOFs), and zeolitic imidazolate frameworks (ZIFs) are essential for the development of separation and reaction technologies. The development of appropriate models requires insights into a wide variety of factors that influence the mobilities of guest molecules in the microporous hosts. Such factors include: molecular size, shape, and configuration, degree of confinement, pore topology and connectivity, strength of adsorption on pore walls, molar loadings of guest constituents, and correlations in the molecular jumps between partner molecules. Experimental data, on their own, do not provide sufficient information to set up the requisite models to describe mixture diffusion. The primary objective of this article is to demonstrate the potency of Molecular Dynamics (MD) simulations to offer insights that assist in the interpretation of experimental observations and development of descriptive models. Computational snapshots and video animations are used to provide a visual appreciation of phenomena such as traffic junction, slowing-down, and hindering effects in diffusion.
      Graphical abstract image

      PubDate: 2017-09-25T19:49:14Z
      DOI: 10.1016/j.micromeso.2017.09.014
      Issue No: Vol. 258 (2017)
       
  • Recyclable ammonia uptake of a MIL series of metal-organic frameworks with
           high structural stability
    • Authors: Yang Chen; Feifei Zhang; Yong Wang; Chengyin Yang; Jiangfeng Yang; Jinping Li
      Pages: 170 - 177
      Abstract: Publication date: 1 March 2018
      Source:Microporous and Mesoporous Materials, Volume 258
      Author(s): Yang Chen, Feifei Zhang, Yong Wang, Chengyin Yang, Jiangfeng Yang, Jinping Li
      Metal-organic frameworks (MOFs) have been rapidly developed in the fields of gas adsorption and storage, but are unsatisfactory in NH3 adsorption due to their unstable structures. Considering NH3 is both a toxic gas and the only carbon-free chemical energy carrier, MOFs exhibit great prospects for the adsorption and storage of NH3 due to their advantages of structural diversity, modifiable structures and high surface area. In this work, we have researched, in detail, the structural characteristics, stability and NH3 adsorption properties of MIL-53, NH2-MIL-53, MIL-100 and MIL-101. In addition, the NH3 adsorption sites have been investigated using Grand canonical Monte Carlo simulations. The results showed that MIL-100 and MIL-101 have a large NH3 uptake of 8 mmol/g and 10 mmol/g, respectively, and that the modified amino functional groups improve the NH3 adsorption capacity in NH2-MIL-53. More importantly, the four MIL materials have reusable NH3 uptake and excellent NH3 (and NH3/H2O) stability, and are promising materials for NH3 adsorption.
      Graphical abstract image

      PubDate: 2017-09-25T19:49:14Z
      DOI: 10.1016/j.micromeso.2017.09.013
      Issue No: Vol. 258 (2017)
       
  • Creating intraparticle mesopores inside ZSM-5 nanocrystals under OSDA-free
           conditions and achievement of high activity in LDPE degradation
    • Authors: Lei Shi; Niping Li; Ling Wang; Ruiyun Liu; Sen Lin; Jing Liu; Runwei Wang; Yi Li
      Pages: 178 - 188
      Abstract: Publication date: 1 March 2018
      Source:Microporous and Mesoporous Materials, Volume 258
      Author(s): Lei Shi, Niping Li, Ling Wang, Ruiyun Liu, Sen Lin, Jing Liu, Runwei Wang, Yi Li
      This work presents a simple method for creating intraparticle mesopores inside ZSM-5 nanocrystals using a polymer/seed co-assisted approach under OSDA (organic structural directing agent)-free conditions. The effects of anionic polyacrylamide (PAM), and some derived synthesis parameters, including PAM concentration, seed concentration, sodium hydroxide concentration, and crystallization temperature on the textural properties of the final product, and especially on the intraparticle mesopore formation mechanism were systematically investigated by XRD, N2-adsorption, UV-Raman, SEM, TEM, solid state 27Al MAS NMR, and 29Si MAS NMR analyses. The proposed mechanism includes (1) Introducing a seed solution to guarantee sufficient nucleation; (2) PAM acceleration of phase separation by “immobilizing” the generated ultrafine MFI structure building units, and so playing the role of a flocculating agent in the induction period; (3) Creation of intraparticle and interparticle mesopores after removal of PAM species by calcination, which can be pre-designed by simply optimizing the synthesis parameters. The synthesis involves severe conditions and as a consequence the resulting nano-sized ZSM-5 zeolite simultaneously possesses very high crystallinity and considerable intraparticle mesoporosity. Because of the existence of intraparticle mesopores, the produced ZSM-5 nanocrystal agglomerates exhibit excellent catalytic performance in the LDPE degradation reaction. The temperature ascribed to the maximum degradation rate was found to be 22 K lower than that measured for the production of common nano-sized ZSM-5 aggregates that do not exhibit intraparticle mesoporosity.
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      PubDate: 2017-09-25T19:49:14Z
      DOI: 10.1016/j.micromeso.2017.09.019
      Issue No: Vol. 258 (2017)
       
  • Fabrication of morphology predictable nanomaterials by leveraging
           mesoporous silica as fabrication reactors
    • Authors: Yingli Zhu; Yujun Liang; Shiqi Liu; Kai Li; Wen Lei
      Pages: 189 - 196
      Abstract: Publication date: 1 March 2018
      Source:Microporous and Mesoporous Materials, Volume 258
      Author(s): Yingli Zhu, Yujun Liang, Shiqi Liu, Kai Li, Wen Lei
      In this study, we propose and demonstrate a novel methodology to fabricate nanomaterials with predictable morphologies and physical/chemical properties. This new fabrication methodology typically comprise the following steps: (i) precursors with specific morphology are coated with mesoporous silica; (ii) the precursors are converted into the target products chemically through the channels of mesoporous silica; (iii) the silica coating shells are removed by NaOH solution or other solutions, leading to the final product. The morphology of the final product is insensitive to external experimental conditions, and only determined by the morphology of the precursors. As a test vehicle, uniform Bi0.96Eu0.04PO4 nanospheres with high light emission efficiency have been successfully fabricated by using Bi0.96Eu0.04 nanospheres as the precursors. This novel fabrication methodology can also be extended to design and fabricate nanomaterials with controlled morphology in other material systems.
      Graphical abstract image

      PubDate: 2017-09-25T19:49:14Z
      DOI: 10.1016/j.micromeso.2017.09.020
      Issue No: Vol. 258 (2017)
       
  • Analyzing microporosity with vapor thermogravimetry and gas pycnometry
    • Authors: A. Petra Dral; Johan E. ten Elshof
      Pages: 197 - 204
      Abstract: Publication date: 1 March 2018
      Source:Microporous and Mesoporous Materials, Volume 258
      Author(s): A. Petra Dral, Johan E. ten Elshof
      The complementary use of thermogravimetry and pycnometry is demonstrated to expand the toolbox for experimental micropore analysis <1 nm. Thermogravimetry is employed to assess the uptake of water, methanol, ethanol, 1-propanol and cyclohexane vapors in microporous structures at room temperature and derive quantitative micropore volumes and minimum pore entrance sizes together with qualitative information on surface chemistries. Pycnometry is employed to measure the uptake and adsorption of helium, argon and nitrogen gas in microporous structures at room temperature and derive semi-quantitative surface-to-volume ratios, surface areas and micropore cavity sizes and qualitative information on the surface chemistries. The method is validated and calibrated by applying it to a series of zeolites with known micropore structures. The results are compared with data from conventional N2 adsorption at −196 °C and CO2 adsorption at 0 °C. Main advantages of the demonstrated method are that diffusion limitations due to cryogenic temperatures are eliminated, adsorption is studied with non-polar gases, micropore cavity sizes are probed separate from micropore entrances and data can be interpreted in a straightforward fashion without requiring theoretical models on molecular behavior. Micropores <1 nm can thus be analyzed with increased accuracy as compared to conventional adsorption isotherm analysis.
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      PubDate: 2017-09-25T19:49:14Z
      DOI: 10.1016/j.micromeso.2017.09.015
      Issue No: Vol. 258 (2017)
       
  • Tailoring the size and microporosity of Stöber silica particles
    • Authors: Dmitry A. Kurdyukov; Daniil A. Eurov; Demid A. Kirilenko; Vasily V. Sokolov; Valery G. Golubev
      Pages: 205 - 210
      Abstract: Publication date: 1 March 2018
      Source:Microporous and Mesoporous Materials, Volume 258
      Author(s): Dmitry A. Kurdyukov, Daniil A. Eurov, Demid A. Kirilenko, Vasily V. Sokolov, Valery G. Golubev
      The influence exerted by addition of [3-(methacryloyloxy) propyl]trimethoxysilane (MPTMOS) on the porosity and size of silica particles synthesized in a water-ethanol-ammonia-tetraethoxysilane (TEOS) mixture by the Stöber-Fink-Bohn method with the subsequent calcination in oxygen at 400 °C was studied. A set of particles was synthesized at the same relative amounts of the starting reagents and at the same temperature of the reaction mixture. It was shown that as the amount of MPTMOS in the TEOS + MPTMOS precursor is raised from 0 to 12.5 mol%, the final size of the resulting SiO2 particles decreases from ∼400 to ∼10 nm, which is presumably due to the increase in the number of nucleation centers by several orders of magnitude. It was found that the particles have micropores, which are presumably formed upon removal of methacryloyloxypropyl groups by calcination. As the MPTMOS:TEOS molar ratio is raised, the micropore volume and the apparent specific surface area of the particles first grow and reach values of 0.15 ≿m3 g−1 (350 m2 g−1), and then decrease to 0.05 ≿m3 g−1 (100 m2 g−1) because the particle size (∼10 nm) becomes comparable with the pore size (1–2 nm). Upon addition of one more porogen, cetyltrimethylammonium bromide (CTAB), to the reaction mixture, the micropore volume and the apparent specific surface area of the particles substantially increase to become 0.25 cm3 g−1 and 600 m2 g−1, correspondingly, and the particle size rises to 50 nm. Probably, mesopores formed upon oxidation of CTAB micelles and micropores are mutually connected and form a common network within the particles. The total pore volume and the specific surface area of the particles determined by BET reach values of 1.05 cm3 g−1 and 1200 m2 g−1, respectively.
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      PubDate: 2017-09-25T19:49:14Z
      DOI: 10.1016/j.micromeso.2017.09.017
      Issue No: Vol. 258 (2017)
       
  • A reconsideration on the definition of the term aerogel based on current
           drying trends
    • Authors: João P. Vareda; Alyne Lamy-Mendes; Luisa Durães
      Pages: 211 - 216
      Abstract: Publication date: 1 March 2018
      Source:Microporous and Mesoporous Materials, Volume 258
      Author(s): João P. Vareda, Alyne Lamy-Mendes, Luisa Durães
      Kistler, in his original definition, stated that aerogels are obtained from gels in which the pore liquid is replaced by air with moderate shrinkage of the matrix. However, aerogels have been commonly seen as materials that are obtained at supercritical drying (SCD) condition, as this is typically the only one generating minimal impact on the porous structure. Other approaches to dry the gels have been introduced long ago, though their employment meant that the gel would suffer substantial changes during drying. Current developments in drying procedures have allowed to dry monolithic gels with a much more moderate impact on the porous matrix without SCD. In this article, several works where monolithic materials dried with non-supercritical conditions are presented and some of their properties are compared against typical properties of aerogels. It is found that many of these feature aerogel-like properties. Based on these findings, a critical reflection on the definitions of aerogels is presented and the suitability of the terms aerogel, xerogel and cryogel is discussed. Aerogels should designate materials derived from gels that are dried with a confirmed moderate impact on the solid network, regardless of the drying approach used. As such, Kistler's definition is the most suited even today. Instead of using a qualitative view of the impact that the solid network suffers during drying, the relevant structural and performance properties of the material must be determined, as well as those of the SCD-dried counterpart, for comparative validation regarding the type of material.
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      PubDate: 2017-09-25T19:49:14Z
      DOI: 10.1016/j.micromeso.2017.09.016
      Issue No: Vol. 258 (2017)
       
  • Use of microwave irradiation for modification of mesoporous silica
           nanoparticles by thioglycolic acid for removal of cadmium and mercury
    • Authors: I.M.M. Kenawy; Y.G. Abou El-Reash; M.M. Hassanien; N.R. Alnagar; W.I. Mortada
      Pages: 217 - 227
      Abstract: Publication date: 1 March 2018
      Source:Microporous and Mesoporous Materials, Volume 258
      Author(s): I.M.M. Kenawy, Y.G. Abou El-Reash, M.M. Hassanien, N.R. Alnagar, W.I. Mortada
      Herein, we report the organized investigation on adsorption of Cd(II) and Hg(II) by thioglycolic acid modified mesoporous silica nanoparticles prepared by the sol-gel procedure. The modification process is enhanced by microwave irradiation. The morphological behavior of the prepared sorbent (MCM-41-TgA) was identified by SEM and TEM imaging as well as BET surface area analysis. The proposed chemical properties were confirmed by elemental analysis, FT-IR, XRD, and zeta potential. EDX and FT-IR spectra were used to confirm the adsorption process. Both ions could be quantitatively recovered from aqueous samples at pH 6 after shaking for 30 min at room temperature. The solid phase has relatively high adsorption capacity 91.3 and 42.8 mg g−1 for Cd(II) and Hg(II), respectively. Langmuir isotherm model fitted well with the experimental data confirming the formation of a mono layer with homogeneous adsorption sites. The thermodynamic studies concluded spontaneity and exothermic behavior of the adsorption process. MCM-41-TgA could be regenerated using 0.5 mol L-11 thiourea or EDTA for at least 10 adsorption/desorption cycles, and it was applied to preconcentrate Cd(II) and Hg(II) from real samples before their determination using ICP-OES.
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      PubDate: 2017-10-04T07:48:59Z
      DOI: 10.1016/j.micromeso.2017.09.021
      Issue No: Vol. 258 (2017)
       
  • Synthesis and structure of analcime and analcime-zirconia composite
           derived from coal fly ash cenospheres
    • Authors: Tatiana A. Vereshchagina; Ekaterina A. Kutikhina; Leonid A. Solovyov; Sergei N. Vereshchagin; Elena V. Mazurova; Yana Yu. Chernykh; Alexander G. Anshits
      Pages: 228 - 235
      Abstract: Publication date: 1 March 2018
      Source:Microporous and Mesoporous Materials, Volume 258
      Author(s): Tatiana A. Vereshchagina, Ekaterina A. Kutikhina, Leonid A. Solovyov, Sergei N. Vereshchagin, Elena V. Mazurova, Yana Yu. Chernykh, Alexander G. Anshits
      Cubic analcime and analcime-zirconia composite with the Si/Al ratio of 2.04 and 2.16, respectively, was synthesized by hydrothermal treatment of coal fly ash cenospheres (Si/Al = 2.7) at 150 °C. The scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), synchronous thermal analysis (STA) methods were used to study the morphology, composition and structure of the products. Two main types of analcime bearing particles were obtained, such as hollow microspheres with attached analcime icositetrahedra of 5–50 μm in size and individual analcime crystals of a narrow particle size distribution (Dm = 41 μm) with incorporated zirconia (4.8 wt% Zr). The high quality of the crystalline fractions allowed an accurate full-profile PXRD analysis of complete analcime crystal structure and composition including anisotropic displacement parameters of all atoms and H-positions of water molecules.
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      PubDate: 2017-10-04T07:48:59Z
      DOI: 10.1016/j.micromeso.2017.09.011
      Issue No: Vol. 258 (2017)
       
  • Tailoring structural and physical properties of polymethylsilsesquioxane
           aerogels by adjusting NH3·H2O concentration
    • Authors: Chaoshuai Lei; Zijun Hu; Yue Zhang; Hailong Yang; Junning Li; Shengbo Hu
      Pages: 236 - 243
      Abstract: Publication date: 1 March 2018
      Source:Microporous and Mesoporous Materials, Volume 258
      Author(s): Chaoshuai Lei, Zijun Hu, Yue Zhang, Hailong Yang, Junning Li, Shengbo Hu
      The polymethylsilsesquioxane (PMSQ) aerogels obtained from the precursor of methyltrimethoxysilane (MTMS) have been a kind of high-performance thermal insulating materials due to its ultra-low thermal conductivity and improved mechanical property. In this paper, a facile way was introduced to control the microstructure of the PMSQ aerogels using a sol-gel system with supercritical ethanol drying. It was found that the skeleton structures changed from the tenuous branched chains to a stronger network of particle aggregates with the increase of NH3·H2O concentration. The pore sizes in the aerogels were controllable and gradually changing from concentrating at ∼10 nm to 40 nm. The effect of different assembly structures on the physical properties were explored in detail. The aerogels with smaller particles and pore sizes are transparent and have the specific surface area as high as 615.0 m2/g, while the particle aggregates and larger pore sizes make the skeleton sturdier, which endow the aerogels with improved resilience ability of 80%. All the aerogels show low thermal conductivity in the range of 20.7–21.4 mW/m·K and hydrophobic property with a contact angle higher than 140°. More importantly, with high ammonia concentration, aerogels obtained by ambient pressure drying have a resilience of 98% and exhibit low thermal conductivity of 22.3 mW/m·K. This extends the range of practical applications for the PMSQ aerogels.
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      PubDate: 2017-10-04T07:48:59Z
      DOI: 10.1016/j.micromeso.2017.05.009
      Issue No: Vol. 258 (2017)
       
  • Nitrogen-containing ordered mesoporous carbon grafted by alkyl bromide:
           Simple synthesis and its catalytic application in solvent-free
           cycloaddition of CO2
    • Authors: Dan Ma; Huan Zheng; Hui-Min Wan; Ye Chen; Jie Xu; Bing Xue
      Pages: 244 - 250
      Abstract: Publication date: 1 March 2018
      Source:Microporous and Mesoporous Materials, Volume 258
      Author(s): Dan Ma, Huan Zheng, Hui-Min Wan, Ye Chen, Jie Xu, Bing Xue
      Nitrogen-containing ordered mesoporous carbon (NOMC) materials were prepared through a soft-templating method and then utilized as supports to immobilize alkyl bromide. The physicochemical properties of the synthesized materials (prop-Br/NOMCs) were characterized by several techniques including N2 adsorption–desorption, small-angle XRD, TEM, XPS, and elemental analysis. As heterogeneous catalysts, the prop-Br/NOMC samples exhibited good catalytic activity and high selectivity in solvent-free cycloaddition of CO2 with propylene oxide (PO). The maximum PO conversion reached ca. 83% at 150 °C. Based on the characterization results, it is speculated that the catalytic active sites are quaternary amines and bromide anions which came from the reaction between heterocyclic nitrogen of NOMC and alkyl bromide.
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      PubDate: 2017-10-04T07:48:59Z
      DOI: 10.1016/j.micromeso.2017.09.022
      Issue No: Vol. 258 (2017)
       
  • A simple and innovative route to remarkably enhance the photocatalytic
           performance of TiO2: Using micro-meso porous silica nanofibers as carrier
           to support highly-dispersed TiO2 nanoparticles
    • Authors: Xuekun Tang; Qiming Feng; Kun Liu; Xianping Luo; Jing Huang; Zishun Li
      Pages: 251 - 261
      Abstract: Publication date: 1 March 2018
      Source:Microporous and Mesoporous Materials, Volume 258
      Author(s): Xuekun Tang, Qiming Feng, Kun Liu, Xianping Luo, Jing Huang, Zishun Li
      TiO2 nanoparticles/micro-meso porous silica nanofibers hybrid photocatalyst (TiO2/MMPSNF) was successfully synthesized by a simple and innovative sol-adhesion method. The composition, crystalline phase, microstructure and surface property of the as-prepared composite material were characterized. The results show that the TiO2/MMPSNF is composed of TiO2 and SiO2 with weight ratio of about 1:1.7. Micro-meso porous silica nanofibers (MMPSNF) is combined with TiO2 nanoparticles through Ti-O-Si bond, which effectively hinders the anatase-to-rutile phase transition and restrains the crystalline growth of TiO2. The microstructure of the TiO2/MMPSNF shows that the highly dispersed TiO2 nanoparticles are uniformly distributed on the surface of the MMPSNF to form a monolayer dispersion structure. The photocatalytic performances of as-prepared samples were evaluated through a series of kinetic tests on degradation of Rhodamine B (RhB). The results show that the TiO2/MMPSNF has much higher adsorption capacity and photocatalytic activity than that of the reference materials of unsupported sol-gel TiO2 and P25 TiO2 nanoparticles. According to the investigation, it is proposed that the MMPSNF can effectively enhance the photocatalytic activity of the hybrid photocatalyst by providing synergistic effect of a highly absorptive substrate and a nano-scaled supporter.
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      PubDate: 2017-10-04T07:48:59Z
      DOI: 10.1016/j.micromeso.2017.09.024
      Issue No: Vol. 258 (2017)
       
  • Hierarchical trimodal macro-mesoporous silica monoliths with co-continuous
           macrostructures and isotropic skeletons constructed by randomly oriented
           SBA-15-type primary particles
    • Authors: Wei Wang; Haibo Long; Tao Li; Yiran Wang; Shaohong Liu; Hongqiang Ru
      Pages: 262 - 268
      Abstract: Publication date: 1 March 2018
      Source:Microporous and Mesoporous Materials, Volume 258
      Author(s): Wei Wang, Haibo Long, Tao Li, Yiran Wang, Shaohong Liu, Hongqiang Ru
      In this work, it is demonstrated that hierarchical mesoporous silica monoliths (HMSMs) with trimodal porosities can be facilely prepared using P123 as structure-directing agent and tetraethoxysilane as precursor. In such HMSMs, classic co-continuous macrostructures with interconnected macropores and smooth isotropic skeletons can be obtained in a tunable way, depending on the synthesis variables, including the amounts of P123 and 1,3,5-trimethylbenzene and acid concentrations. Skeletons feature randomly oriented SBA-15-type primary particles with 2D hexagonally ordered mesochannels largely accessible from bimodal macropores. Co-continuous macropore size of a typical HMSM (P1.2) is 19.6 μm, intra-skeleton macropore of 1.9 μm and mesopore size of 9.9 nm. The BET surface area by N2 sorption and total pore volume by Archimedes principle reach 590 m2 g-1 and 3.56 cm3 g-1, respectively. Based on systematic study on the relationship between synthetic compositions and porous structures, the ternary diagram and formation mechanism of these HMSMs were analyzed.
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      PubDate: 2017-10-04T07:48:59Z
      DOI: 10.1016/j.micromeso.2017.09.023
      Issue No: Vol. 258 (2017)
       
  • Influence of the synthesis conditions on the incorporation of B and the
           acidity in B-MCM-41 materials
    • Authors: Eliana G. Vaschetto; Gina A. Pecchi; Sandra G. Casuscelli; Griselda A. Eimer
      Pages: 269 - 276
      Abstract: Publication date: 1 March 2018
      Source:Microporous and Mesoporous Materials, Volume 258
      Author(s): Eliana G. Vaschetto, Gina A. Pecchi, Sandra G. Casuscelli, Griselda A. Eimer
      B-MCM-41 type nano-structured materials were prepared by direct hydrothermal synthesis. The time of hydrothermal treatment, the Si/B initial molar ratio and the nature of the hydroxide source in the synthesis process were analyzed. All the materials were characterized by XRD, N2 adsorption, TEM, SEM, ICP-OES, FT-IR and adsorption of pyridine coupled to FT-IR spectroscopy. The role of hydroxide source is essential to achieve the incorporation of boron in the mesoporous structure. The relationship between the Boron content in the synthesis gel, the degree of introduction of tetra-coordinated B into the framework, the formation of nest silanols and the relative density of the acidic sites have been discussed. We could corroborate that hydroxyl groups present in silanol nests are the direct responsible of the moderate Brønsted acidity of our materials. The enhancement in the density of acidic nest silanols was reached by increasing the B content in the mesoporous structure. Finally, the use of NH4OH, as hydroxide source, Si/B initial molar ratio of 10 and 20 and a hydrothermal treatment of 6 days resulted the optimum synthesis conditions to obtain the highest framework B incorporation and more abundant moderate Brønsted sites (silanol nests), thus improving the potential catalytic properties of these materials.
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      PubDate: 2017-10-04T07:48:59Z
      DOI: 10.1016/j.micromeso.2016.06.039
      Issue No: Vol. 258 (2017)
       
  • Heteroatom-doped porous carbons with enhanced carbon dioxide uptake and
           excellent methylene blue adsorption capacities
    • Authors: Binling Chen; Zhuxian Yang; Guiping Ma; Dali Kong; Wei Xiong; Jinbo Wang; Yanqiu Zhu; Yongde Xia
      Pages: 1 - 8
      Abstract: Publication date: February 2018
      Source:Microporous and Mesoporous Materials, Volume 257
      Author(s): Binling Chen, Zhuxian Yang, Guiping Ma, Dali Kong, Wei Xiong, Jinbo Wang, Yanqiu Zhu, Yongde Xia
      Heteroatom nitrogen and oxygen-doped porous carbon materials were for the first time generated via a one-pot carbonization of metal-organic framework under argon saturated water steam at an elevated temperature. The water steam carbonization of metal-organic frameworks is a novel approach to generate carbon materials with large pore volumes, high surface areas, abundant nitrogen content and enhanced oxygen-containing functional groups. The resulting porous carbon materials exhibited excellent performance in both the carbon dioxide uptake and methylene blue removal from wastewater. A carbon dioxide uptake capacity of 4.00 mmol g−1 at room temperature and a methylene blue adsorption capacity of 98.5% can be achieved. This report offers an alternative strategy to develop metal-organic-frameworks-derived porous carbon materials with new functionalities to meet the specific needs in various adsorption applications.
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      PubDate: 2017-09-02T10:45:50Z
      DOI: 10.1016/j.micromeso.2017.08.026
      Issue No: Vol. 257 (2017)
       
  • Mesoporous/microporous silica materials: Preparation from natural sands
           
    • Authors: Liping Sheng; Yun Zhang; Fujuan Tang; Shiquan Liu
      Pages: 9 - 18
      Abstract: Publication date: February 2018
      Source:Microporous and Mesoporous Materials, Volume 257
      Author(s): Liping Sheng, Yun Zhang, Fujuan Tang, Shiquan Liu
      The chemical and mineral compositions, particle size, hydrothermal dissolubility of four silica sands with different origins, including two sands from crushed quartz stones, one from a desert and one from a sea bed deposit, and their availability to synthesize nanoporous silica have been carefully analyzed and compared. The results indicate that irrespective of the chemical composition and crystallinity, the four sands show similar dissolution trends in alkaline solutions under hydrothermal conditions, that is, the dissolubilities of the sands increase with treatment temperature, time and the alkaline concentration. The main difference in the dissolubilities of the four sands is correlated with the differences in the sand particle size. The larger the size, the smaller the dissolubility. The dissolved silica solutions were successfully used as silica source to prepare mesoporous/microporous silicas without significant difference. The yield of the synthesized silicas decreases sharply when the pH of the dissolved silica sand solution was adjusted to be higher than 9.5. The meso- and micro-silicas prepared at pH of 9.5 and 11 using the cheaper sand from a desert were evaluated in the fixed-bed adsorption of methylene blue (MB) from aqueous solution. It is found that both silicas have good fixed-bed performance toward MB. And the adsorption well fits the Thomas model. The column packed with the microporous silica has longer breakthrough and exhaustion times than with the mesoporous one.
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      PubDate: 2017-09-02T10:45:50Z
      DOI: 10.1016/j.micromeso.2017.08.023
      Issue No: Vol. 257 (2017)
       
  • Ultra-microporous N-doped carbon from polycondensed framework precursor
           for CO2 adsorption
    • Authors: Zhihong Tian; Jiajia Huang; Xin Zhang; Gonglei Shao; Qiuyun He; Shaokui Cao; Siguo Yuan
      Pages: 19 - 26
      Abstract: Publication date: February 2018
      Source:Microporous and Mesoporous Materials, Volume 257
      Author(s): Zhihong Tian, Jiajia Huang, Xin Zhang, Gonglei Shao, Qiuyun He, Shaokui Cao, Siguo Yuan
      High adsorption capacity and selectivity of microprous carbon are critical for exceptional post-combustion CO2 capture ability. Herein we report a novel strategy to prepare N-doped microprous carbon with high surface area (2363 m2 g−1 for CPTHB-7), narrow pore size distribution and high ultramicropore ratio (<0.7 nm, 68% for CPTHB-6) via a simple chemical activation of a rigid polymer porous framework (PTHB) synthesized via polycondensation reaction of 1,3,5-THB and aniline. The as-prepared microprous carbon exhibit high CO2 adsorption capacities of 5.6–6.3 mmol g−1 (273 K and 1 bar) and sufficient CO2/N2 selectivity of 12–22 for a 0.15/0.85 CO2/N2 mixture at 298 K and 1 bar (conditions of CO2 capture application). The effect of microporosity and N content for our materials on the CO2 adsorption performance had also been investigated. Microporous volume below critical size contributed to the adsorption capacity for CO2, while the N content and nitrogen species play a role in the CO2/N2 selectivity.
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      PubDate: 2017-09-02T10:45:50Z
      DOI: 10.1016/j.micromeso.2017.08.012
      Issue No: Vol. 257 (2017)
       
  • Ni-Biurea complex anchored onto MCM-41: As an efficient and recyclable
           nanocatalyst for the synthesis of 2,3-dihydroquinazolin-4(1H)-ones
    • Authors: Hana Batmani; Nader Noroozi Pesyan; Forugh Havasi
      Pages: 27 - 34
      Abstract: Publication date: February 2018
      Source:Microporous and Mesoporous Materials, Volume 257
      Author(s): Hana Batmani, Nader Noroozi Pesyan, Forugh Havasi
      Ni-Biurea complex supported on functionalized MCM-41 was prepared by a post-grafting method and used as an efficient, recoverable and thermally stable nanocatalyst for the one-pot synthesis of 2,3-dihydroquinazolin-4(1H)-ones from 2-aminobenzamide and aromatic aldehydes in PEG. This nanocatalyst was characterized using FT-IR, XRD, SEM, TGA, EDS, ICP and BET techniques. The heterogeneous catalyst showed good recyclability and can be reused for five consecutive cycles without significant loss of its catalytic activity.
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      PubDate: 2017-09-02T10:45:50Z
      DOI: 10.1016/j.micromeso.2017.08.024
      Issue No: Vol. 257 (2017)
       
  • Hierarchical zeolite Y as hosts for encapsulation of Fe-Schiff base
           complexes
    • Authors: Yanpeng Zhao; Wenmiao Lv; Ningyue Lu; Xiufeng Shi; Binbin Fan; Ruifeng Li
      Pages: 35 - 41
      Abstract: Publication date: February 2018
      Source:Microporous and Mesoporous Materials, Volume 257
      Author(s): Yanpeng Zhao, Wenmiao Lv, Ningyue Lu, Xiufeng Shi, Binbin Fan, Ruifeng Li
      A series of hierarchical zeolite Y samples with different hierarchical qualities, were used as hosts for encapsulation of metal complexes, and their host effects were investigated by XRD, N2 adsorption/desorption, TGA, DR UV-vis, ICP, elemental analysis as well as catalytic reaction. Hierarchical zeolite Y, due to the presence of mesopores, greatly facilitated the transport of Salcn (H2salicyhexen) ligand in zeolite Y crystals, thus the Fe ions exchanged in the cavities of zeolite Y could fully coordinate with ligands, resulting in the prepared hybrids with less un-complexed Fe ions. FeSalcn complexes encapsulated in the hierarchical zeolite Y showed higher catalytic activities than those in the conventional microporous zeolite Y in various cycloalkane oxidation reactions. This can be ascribed to the reduced diffusion constraint imposed by the micropore of zeolite Y and the increased accessibility of encapsulated FeSalcn active sites. Furthermore, the metal complexes encapsulated in the hierarchical zeolite Y exhibited well reusability as those in the conventional zeolite Y. This work gives insights into the host effects of hierarchical zeolite Y on the preparation and catalytic performance of zeolite-encapsulated complexes.
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      PubDate: 2017-09-02T10:45:50Z
      DOI: 10.1016/j.micromeso.2017.08.021
      Issue No: Vol. 257 (2017)
       
  • Scaling-up of mesoporous silica films via an eco-efficient UV processing
           method. Part 1: Photoinduced mesostructuration
    • Authors: Mathilde Sibeaud; H. De Paz-Simon; C. Croutxé-Barghorn; S. Rigolet; L. Michelin; B. Lebeau; L. Vidal; P.-A. Albouy; A. Chemtob
      Pages: 42 - 50
      Abstract: Publication date: February 2018
      Source:Microporous and Mesoporous Materials, Volume 257
      Author(s): Mathilde Sibeaud, H. De Paz-Simon, C. Croutxé-Barghorn, S. Rigolet, L. Michelin, B. Lebeau, L. Vidal, P.-A. Albouy, A. Chemtob
      Designing sustainable and industrially viable processing methods to synthesize ordered mesoporous films is a necessary condition to tap their full potential of applications. In order to respond to this challenge, well-established photoacid-catalyzed sol-gel photopolymerization has been harnessed to prepare large (>100 cm2) and micrometer-thick porous silica films possessing a 2D hexagonal mesostructure. Our UV irradiation system consists of two inexpensive and low radiant power fluorescent UV tubes (3 mW cm−2, 280–380 nm) enclosed in a hygrometric chamber. Precise conditions to promote copolymer/silica hybrid film mesostructuration have been determined as regards relative humidity, film thickness and templating agent concentration. The mesostructured films have been analyzed using an extensive range of techniques including electron microscopy, grazing-incidence small-angle X-ray scattering (GISAXS), and N2 sorption measurements, and solid-state NMR spectroscopy. Mesoporous silica films with a specific surface area up to 314 m2 g−1 have been achieved with a very low level of microporosity. Coupling of X–ray diffraction (XRD) and FTIR spectroscopy has enabled to shed light into the photoinduced self-assembly mechanism.
      Graphical abstract image

      PubDate: 2017-09-02T10:45:50Z
      DOI: 10.1016/j.micromeso.2017.08.017
      Issue No: Vol. 257 (2017)
       
  • β-galactosidase covalent immobilization over large-pore mesoporous silica
           supports for the production of high galacto-oligosaccharides (GOS)
    • Authors: Isabel González-Delgado; Yolanda Segura; Antonio Martín; María-José López-Muñoz; Gabriel Morales
      Pages: 51 - 61
      Abstract: Publication date: February 2018
      Source:Microporous and Mesoporous Materials, Volume 257
      Author(s): Isabel González-Delgado, Yolanda Segura, Antonio Martín, María-José López-Muñoz, Gabriel Morales
      Large-pore mesoporous silica supports with different structure and pore sizes distribution have been tested for glyoxyl multipoint covalent immobilization of Pectinex Ultra SP-L, a commercial preparation including the enzyme β-galactosidase from Aspergillus aculeatus. The prepared biocatalysts have been assayed in the production of galacto-oligosaccharides (GOS) from lactose as prebiotic functional food, aiming to optimize the yield to the GOS having the highest presumed prebiotic effect, tri- and tetra- GOS (high-GOS). Immobilization of β-galactosidase over glyoxyl-modified silica supports, with pores, large enough to accommodate the enzyme within their structure, led to an enhancement of the enzyme activity in terms of high-GOS production relative to the free enzyme under the same reaction conditions. Remarkably, such an improvement was achieved without previous purification of β-galactosidase from the commercial source. An enhancement of the transgalactosylation activity over the hydrolytic activity, due to the relatively hydrophobic nature of organically modified silica surface of the supports, led to an increase in the selectivity to high-GOS. The best biocatalyst in the series was that based in hexagonal ultra-large-pore SBA-15 (ULP-SBA-15), which presents the most adequate balance between confinement effect within its pore framework and transgalactosylation activity leading to a remarkable yield to high-GOS of 20.2% vs. 11.2% for the enzyme in free conditions. Furthermore, reusability of these silica-based biocatalysts in three consecutive 24 h reaction-cycles has been successfully performed at 50 °C, temperature that minimizes the thermal deactivation of the enzyme.
      Graphical abstract image

      PubDate: 2017-09-02T10:45:50Z
      DOI: 10.1016/j.micromeso.2017.08.020
      Issue No: Vol. 257 (2017)
       
  • Stochastic models of disordered mesoporous materials for small-angle
           scattering analysis and more
    • Authors: Cedric J. Gommes
      Pages: 62 - 78
      Abstract: Publication date: February 2018
      Source:Microporous and Mesoporous Materials, Volume 257
      Author(s): Cedric J. Gommes
      Small-angle scattering of either x-rays (SAXS) or neutrons (SANS) is one of the few experimental techniques that can be used to study the structure of porous materials on the entire range from 1 to 100 nm, which makes it particularly suited for mesoporous materials. Because the information in scattering patterns is a correlation function, models are generally needed to convert data into structurally meaningful information. In this paper, we discuss five stochastic models that capture qualitatively different disordered structures, notably concerning the connectivity and the tortuosity of the phases. The models are two variants of the Boolean model, a dead leaves model, as well as two clipped Gaussian field models. The paper is illustrated with the SAXS analysis of a polymer xerogel, of a fumed silica as well as of a mesoporous alumina, and the fitted models are compared with pore size distributions derived from nitrogen adsorption. In the case of the xerogel and silica it is possible to pinpoint a single model that describes the structure best. In the case of the alumina, however, the scattering cannot discriminate the models. Even so, the models are useful because they enable one to quantitate the structural ambiguity of the SAXS data.
      Graphical abstract image

      PubDate: 2017-09-02T10:45:50Z
      DOI: 10.1016/j.micromeso.2017.08.009
      Issue No: Vol. 257 (2017)
       
  • Seed-assisted synthesis of FER/MOR composite zeolite and its specific
           catalytic application in carbonylation reaction
    • Authors: Xiujie Li; Xiaofang Chen; Zhiqiang Yang; Xiangxue Zhu; Shutao Xu; Sujuan Xie; Shenglin Liu; Xuebin Liu; Longya Xu
      Pages: 79 - 84
      Abstract: Publication date: February 2018
      Source:Microporous and Mesoporous Materials, Volume 257
      Author(s): Xiujie Li, Xiaofang Chen, Zhiqiang Yang, Xiangxue Zhu, Shutao Xu, Sujuan Xie, Shenglin Liu, Xuebin Liu, Longya Xu
      A series of FER/MOR composite zeolites were synthesized through seed-assisted organic template free route. And the FER/MOR composite zeolites exhibited specific catalytic performance in the dimethyl ether carbonylation to methyl acetate reaction. SEM images revealed that the FER circle plates grew along the surface of MOR bundle aggregates. Good pore connectivity and high adsorption capacity were observed on FER/MOR on basis of the hyperpolarized (HP) 129Xe NMR spectra and propane adsorption results, which was different from its corresponding mechanical mixture. Quantitative analysis of 1H MAS NMR spectra using pyridine as probe revealed that the total Brϕnsted acid density in FER/MOR, especially that in 8 MR channel, was higher than that of single zeolites. High Brϕnsted acid density and good pore connectivity guaranteed the superior performance of FER/MOR in DME carbonylation reaction.
      Graphical abstract image

      PubDate: 2017-09-02T10:45:50Z
      DOI: 10.1016/j.micromeso.2017.07.058
      Issue No: Vol. 257 (2017)
       
  • Polyaniline-derived hierarchically porous nitrogen-doped carbons as gas
           adsorbents for carbon dioxide uptake
    • Authors: Xin Li; Zhu-Yin Sui; Ya-Nan Sun; Pei-Wen Xiao; Xu-Yun Wang; Bao-Hang Han
      Pages: 85 - 91
      Abstract: Publication date: February 2018
      Source:Microporous and Mesoporous Materials, Volume 257
      Author(s): Xin Li, Zhu-Yin Sui, Ya-Nan Sun, Pei-Wen Xiao, Xu-Yun Wang, Bao-Hang Han
      In this work, hierarchically porous nitrogen-doped carbon materials (PNCs) are prepared through a physical activation process by using carbon dioxide as an activating agent and polyaniline as a precursor. The morphology, porous property, and chemical attribute of PNCs are investigated through different technical methods, such as scanning electron microscopy, nitrogen adsorption–desorption measurement, and X-ray photoelectron spectroscopy. The textural property of PNCs can be tuned by varying the activation time. PNCs display high specific surface areas (1030–2900 m2 g−1) and large pore volumes (0.66–1.87 cm3 g−1). When taken as adsorbents for gas capture, PNCs exhibit high carbon dioxide capture capacities (17.2–21.5 wt% at 273 K and 1.0 bar) and good selective adsorption of carbon dioxide over nitrogen or methane. The superior performance can be ascribed to the high porosity, suitable pore size, and the presence of nitrogen functional groups.
      Graphical abstract image

      PubDate: 2017-09-02T10:45:50Z
      DOI: 10.1016/j.micromeso.2017.08.027
      Issue No: Vol. 257 (2017)
       
  • Synthesis and characterization of novel Ti doped hexagonal mesoporous
           silica catalyst for nonenzymatic hydrogen peroxide oxidation
    • Authors: Derya Düzenli; Özlem Sahin; Hilal Çelik Kazıcı; Nahit Aktaş; Hilal Kivrak
      Pages: 92 - 98
      Abstract: Publication date: February 2018
      Source:Microporous and Mesoporous Materials, Volume 257
      Author(s): Derya Düzenli, Özlem Sahin, Hilal Çelik Kazıcı, Nahit Aktaş, Hilal Kivrak
      A new electrocatalyst, Ti-HMS was successfully synthesized by sol-gel method employing Ti source tetrabutyl orthotitanate (TBOT) and silica source tetraethyl orthosilicate (TEOS, 99% purity). Ti-HMS catalysts were prepared at varying Ti:Si ratios by employing sol-gel method. Physicochemical properties of these nanoparticles were characterized and confirmed by BET, TG-DTA, XPS, and XRD. Electrochemical properties of Ti-HMS catalysts prepared at varying Ti:Si ratios were examined by cyclic voltammetry (CV) and chronoamperometry (CA) for determination of the oxidation and reduction activity of H2O2. It was observed that the Ti-HMS (Ti:Si = 0.02) electrode exhibits significant oxidation and reduction of H2O2 at applied potentials of 0.65 V and −0.30 V with the addition of H2O2, respectively. The excellent electrocatalytic response to H2O2 is mainly attributed to varying electronic properties with the incorporation of Ti to HMS.
      Graphical abstract image

      PubDate: 2017-09-02T10:45:50Z
      DOI: 10.1016/j.micromeso.2017.08.030
      Issue No: Vol. 257 (2017)
       
  • Influence of network modifiers in an acetate based sol-gel bioactive glass
           system
    • Authors: Delihta Fernando; Nina Attik; Mark Cresswell; Ilham Mokbel; Nelly Pradelle-Plasse; Phil Jackson; Brigitte Grosgogeat; Pierre Colon
      Pages: 99 - 109
      Abstract: Publication date: February 2018
      Source:Microporous and Mesoporous Materials, Volume 257
      Author(s): Delihta Fernando, Nina Attik, Mark Cresswell, Ilham Mokbel, Nelly Pradelle-Plasse, Phil Jackson, Brigitte Grosgogeat, Pierre Colon
      The aim of this study was to assess the influence of CaO/Na2O ratio on the structural and textural properties of mesoporous bioactive glasses generated from an acetic acid catalysed acetate based sol-gel system. The glass network formers (SiO2 and P2O5) were fixed and the network modifiers were varied [75SiO2:XCaO:(15-X)Na2O:10P2O5 where X = 5, 10, 15, in mole percent] such that increasing alkaline earth oxide is compensated by decreasing alkali oxide. The glass properties were assessed using techniques such as XRF, XRD, FTIR, BET/BJH, SEM, TEM and ICP. The rapid gelling of the sol resulted in the deposition of the calcium and sodium acetate precursors on the particle surface which required thermal treatment to facilitate their entry into the glass network. The results of our study demonstrated that the porosity was clearly driven by CaO in the composition possibly due to its inferior fluxing effect in comparison to Na2O. The sample with highest CaO content reached a high surface area and pore volume (535 m2 g−1 and 0.33 cm3 g−1) even in a non-surfactant based preparation suggesting that acetic acid catalysed acetate system favours improved textural properties. In vitro SBF tests confirmed the potential of the sample with highest CaO for earlier apatite formation.
      Graphical abstract image

      PubDate: 2017-09-02T10:45:50Z
      DOI: 10.1016/j.micromeso.2017.08.029
      Issue No: Vol. 257 (2017)
       
  • Preparation of mesoporous palladium nanoclusters supported over hematite
           (α-Fe2O3) for selective catalytic hydrogenation of α,β-unsaturated
           aldehydes
    • Authors: Mostafa Farrag
      Pages: 110 - 117
      Abstract: Publication date: February 2018
      Source:Microporous and Mesoporous Materials, Volume 257
      Author(s): Mostafa Farrag
      Atomically precise monodisperse palladium nanoclusters protected by N-acetyl-l-cysteine (Pdn(NALC)m) ligand were synthesized. Protected nanoclusters block the mesoporous pores of supports and decrease their specific surface area after loading with 1 wt % as found in our previous work. The new synthesized palladium clusters with special crystal structure did not block the mesoporous pores of iron oxide support (α-Fe2O3). Moreover, the pore volume and pore diameter of the support was increased by synthesizing palladium clusters with 1 wt % dopant. The doped catalyst was irradiated by microwave synthesis labstation 1 h at 80 °C and 500 W to gently remove of the protected N-acetyl-l-cysteine ligands and produce bare palladium clusters supported on iron oxide. The particles size of the synthesized palladium clusters was investigated by high resolution transmission electron microscope (HRTEM). The spectroscopic properties and chemical composition of Pdn(NALC)m clusters were studied by UV-vis spectroscopy and thermogravimetric analysis (TGA), elemental analysis and atomic absorption spectroscopy. FTIR was used for the free ligand (NALC) and the protected palladium cluster, where the disappearance of the S–H vibrational band at 2535–2570 cm−1 in the palladium clusters spectrum confirmed the ligand is anchored to the cluster surface through the sulfur atom. The crystallinity of the bare iron oxide and the doped palladium clusters (1%Pdn(NALC)m/α-Fe2O3) and the microwave treated catalyst (1% Pdn/α-Fe2O3) were determined by powder X-ray diffraction analysis. BET surface area, pore volume and average pore diameter were investigated via nitrogen adsorption at −196 °C. The catalytic properties of atomically precise palladium nanoclusters supported on iron oxide were investigated for reduction of cinnamaldehyde as example for α,β-unsaturated aldehydes. The catalytic activity of synthesized catalysts increased in this order 1% Pdn/α-Fe2O3 > 1% Pdn(NALC)m/α-Fe2O3 > Pdn(NALC)m. The catalytic reduction reaction in toluene was performed at temperature 20–80 °C. The aforementioned synthesized catalysts showed 100% chemoselectivity in the reduction of cinnamaldehyde at room temperature.
      Graphical abstract image

      PubDate: 2017-09-02T10:45:50Z
      DOI: 10.1016/j.micromeso.2017.08.022
      Issue No: Vol. 257 (2017)
       
  • A ternary balance of chemical-anchoring/self-assembly/crystallization: The
           key to the construction of intracrystalline mesopores
    • Authors: Junsu Jin; Fan Hu; Honghai Liu; Jia Zhao; Xionghou Gao; Qingting Meng; Xiaotong Mi; Hongtao Liu; Chunyan Xu; Jingchang Zhang
      Pages: 118 - 127
      Abstract: Publication date: February 2018
      Source:Microporous and Mesoporous Materials, Volume 257
      Author(s): Junsu Jin, Fan Hu, Honghai Liu, Jia Zhao, Xionghou Gao, Qingting Meng, Xiaotong Mi, Hongtao Liu, Chunyan Xu, Jingchang Zhang
      Zeolite Y with intracrystalline mesopores has been synthesized by controlling a ternary balance (chemical anchoring of the template on zeolite framework, mesoporous self-assembly around the template, and crystallization of zeolite Y). The rapid hydrolysis of (CH3O)3Si- to -Si-OH and the subsequent linkage to zeolite framework were crucial for the formation of intracrystalline mesopores. The high concentration of OH- in the initial systems favors the self-assembly of well-ordered mesophases due to the high stability of Dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (TPOACl) micelles. The well-ordered mesopores transfer to wormlike because the solubility of TPOACl increase with the decreased alkalinity by prolonging crystallization of zeolite Y. The materials with relatively well crystallized zeolite Y and high mesopores surface area showed better catalytic properties than the conventional Y and alone well-ordered mesoporous materials. The obtained sample exhibited improved catalytic performance in heavy oil cracking. The yield of the light fraction (gasoline + diesel) of the Cat-2 catalysts is 63.4 wt%, much higher than that of Cat-1 (49.9 wt%) and the Coke yield of Cat-2 is 12.1%, much lower than that of Cat-3 (15.2%).
      Graphical abstract image

      PubDate: 2017-09-02T10:45:50Z
      DOI: 10.1016/j.micromeso.2017.08.028
      Issue No: Vol. 257 (2017)
       
  • Alkane/alkene mixture diffusion in silicalite-1 studied by MAS PFG NMR
    • Authors: Nina Dvoyashkina; Dieter Freude; Alexander G. Stepanov; Winfried Böhlmann; Rajamani Krishna; Jörg Kärger; Jürgen Haase
      Pages: 128 - 134
      Abstract: Publication date: February 2018
      Source:Microporous and Mesoporous Materials, Volume 257
      Author(s): Nina Dvoyashkina, Dieter Freude, Alexander G. Stepanov, Winfried Böhlmann, Rajamani Krishna, Jörg Kärger, Jürgen Haase
      The diffusivity of n-alkanes and n-alkenes (C2 to C6) and their mixtures in silicalite-1 was studied by magic-angle spinning pulsed field-gradient nuclear magnetic resonance (MAS PFG NMR) at the temperatures of 273 K, 313 K and 373 K. It could be proved that there is no significant difference between the diffusivities of alkanes, alkenes and their mixtures for equal carbon numbers and equal total loading. The diffusivities of the alkanes, alkenes and their mixtures are found to monotonically decrease with increasing carbon number, in agreement with the results obtained in MD simulations with n-alkanes in silicalite-1.
      Graphical abstract image

      PubDate: 2017-09-02T10:45:50Z
      DOI: 10.1016/j.micromeso.2017.08.015
      Issue No: Vol. 257 (2017)
       
  • Synergic effect of Zn and Cu oxides dispersed on activated carbon during
           reactive adsorption of H2S at room temperature
    • Authors: Giacomo de Falco; Fabio Montagnaro; Marco Balsamo; Alessandro Erto; Fabio Alessandro Deorsola; Luciana Lisi; Stefano Cimino
      Pages: 135 - 146
      Abstract: Publication date: February 2018
      Source:Microporous and Mesoporous Materials, Volume 257
      Author(s): Giacomo de Falco, Fabio Montagnaro, Marco Balsamo, Alessandro Erto, Fabio Alessandro Deorsola, Luciana Lisi, Stefano Cimino
      The origin of the synergic effect of zinc and copper oxides (ZnO-CuO) supported onto activated carbon on the removal of hydrogen sulphide (H2S) from gaseous streams at low temperature is investigated in this work. Sorbents with a fixed total metal content and variable Zn:Cu ratios were prepared by impregnation of a commercial activated carbon. H2S (100–3000 ppmv in N2) removal tests were run under dynamic conditions at 30 °C and compared through analysis of their breakthrough curves, adsorption rates and values of adsorption capacity. Fresh and spent sorbents were characterized by BET and pore size distribution via N2-adsorption, SEM-EDX and XPS. TPD/TPO experiments from partially and completely saturated sorbents allowed the speciation of adsorbed sulphur species, testifying the complexity of the surface reactions which strongly depended on the Zn:Cu ratio, on the interactions of metal oxides with activated carbon and on the textural properties of the sorbent.
      Graphical abstract image

      PubDate: 2017-09-02T10:45:50Z
      DOI: 10.1016/j.micromeso.2017.08.025
      Issue No: Vol. 257 (2017)
       
  • Synthesis of 3-Acyloxylindolines under mild conditions using
           tripolyphosphate-grafted KCC-1-NH2
    • Authors: Seyed Mohsen Sadeghzadeh; Rahele Zhiani; Mehdi Khoobi; Shokufe Emrani
      Pages: 147 - 153
      Abstract: Publication date: February 2018
      Source:Microporous and Mesoporous Materials, Volume 257
      Author(s): Seyed Mohsen Sadeghzadeh, Rahele Zhiani, Mehdi Khoobi, Shokufe Emrani
      The aim of this investigation is recycling, reusability and stability of the KCC-1 as a suport's catalyst. KCC-1 and its functionalized derivatives of aminopropyltriethoxysilane and tripolyphosphate (ATPP) have been synthesized, and applied to one-pot synthesis of 3-Acyloxylindolines for first time from 2-aminostyrene with carboxylic acid.
      Graphical abstract image

      PubDate: 2017-09-02T10:45:50Z
      DOI: 10.1016/j.micromeso.2017.08.037
      Issue No: Vol. 257 (2017)
       
  • Synergy effect between hierarchical structured and Sn-modified H[Sn,
           Al]ZSM-5 zeolites on the catalysts for glycerol aromatization
    • Authors: Xinghui Yang; Fei Wang; Ruiping Wei; Shuai Li; Yuanfeng Wu; Pengxin Shen; Huazheng Wang; Lijing Gao; Guomin Xiao
      Pages: 154 - 161
      Abstract: Publication date: February 2018
      Source:Microporous and Mesoporous Materials, Volume 257
      Author(s): Xinghui Yang, Fei Wang, Ruiping Wei, Shuai Li, Yuanfeng Wu, Pengxin Shen, Huazheng Wang, Lijing Gao, Guomin Xiao
      Hierarchical H[Sn, Al]ZSM-5 zeolites were successfully prepared by hydrothermal method with directly incorporating Sn species into framework of HZSM-5 zeolites followed by alkali treatment. The prepared samples were characterized by XRD, BET, SEM-EDX, TEM, NH3-TPD, FT-IR and Py-IR. The results indicate that Sn species were successfully incorporated into HZSM-5 zeolites. The catalytic performances of all prepared zeolites were evaluated by glycerol aromatization. The highest catalytic performance of GTA synthesis was observed with H[Sn, Al]ZSM-5 treated with 0.3 M NaOH (32.1% carbon yield of BTX aromatics and 13 h catalyst lifetime), which was prior to the pure HZSM-5 (17.8% carbon yield of BTX aromatics and 3 h catalyst lifetime). The remarkably improved performance in catalytic activity and stability of H[Sn, Al]ZSM-5/0.3AT zeolitize could be attributed to synergy effect between Sn species doped into HZSM-5 zeolite and the generated micro-mesoporous structure by alkali treatment.
      Graphical abstract image

      PubDate: 2017-09-02T10:45:50Z
      DOI: 10.1016/j.micromeso.2017.08.039
      Issue No: Vol. 257 (2017)
       
  • Direct synthesis of homogeneous Zr-doped SBA-15 mesoporous silica via
           masking zirconium sulfate
    • Authors: Taotao Qiang; Jing Zhao; Ji Li
      Pages: 162 - 174
      Abstract: Publication date: February 2018
      Source:Microporous and Mesoporous Materials, Volume 257
      Author(s): Taotao Qiang, Jing Zhao, Ji Li
      Incorporating zirconium is one of the most widely applied method to functionalize the inert mesoporous silica. However, the conventional zirconium precursors are are costly and poisonous, and zirconium distributes unevenly in Zr-SBA-15. Herein, a homogeneous Zr-doped SBA-15 material (Zr-SBA-15) has been synthesized by employing the low-cost and nontoxic zirconium sulfate as metal precursor. Furthermore, different coordinating ligands including cholamine, diethanol amine, triethanolamine, pentaerythritol, lactic acid and oxalic acid were used as masking agent to mask zirconium sulfate. The masking effects of coordinating ligands on zirconium sulfate were investigated in the synthesis of Zr-SBA-15. It was found that the introduction of coordinating ligands has a remarkable masking effects on preventing the rapid hydrolysis of zirconium sulfate. The obtained Zr-SBA-15 shows an uniform zirconium dispersion (EDS mapping results) with outstanding texture property (SBET of 806 m2 g−1, DBJH of 6.6 nm and VBJH of 0.99 cm3 g−1). Computational simulations was performed for qualitative comparison of masking ability, and the validity of experimental results was theoretically confirmed as well.
      Graphical abstract image

      PubDate: 2017-09-02T10:45:50Z
      DOI: 10.1016/j.micromeso.2017.08.041
      Issue No: Vol. 257 (2017)
       
  • Mesoporous metal - silica materials: Synthesis, catalytic and thermal
           properties
    • Authors: Khachatur V. Manukyan; Armenuhi V. Yeghishyan; Christopher E. Shuck; Dmitry O. Moskovskikh; Sergei Rouvimov; Eduardo E. Wolf; Alexander S. Mukasyan
      Pages: 175 - 184
      Abstract: Publication date: February 2018
      Source:Microporous and Mesoporous Materials, Volume 257
      Author(s): Khachatur V. Manukyan, Armenuhi V. Yeghishyan, Christopher E. Shuck, Dmitry O. Moskovskikh, Sergei Rouvimov, Eduardo E. Wolf, Alexander S. Mukasyan
      Here, we report a simple and scalable synthesis strategy of metal (Ni or Cu) nanoparticles uniformly distributed inside a mesoporous silica matrix. This method involves incorporation of metal nitrates and citric acid in a stable silica gel through controlled hydrolysis of tetraethyl orthosilicate. Combustion of dried gels with ammonium nitrate in an inert gas atmosphere enables preparation of highly porous Ni/SiO2 and Cu/SiO2 nanomaterials with tunable metal content (∼5–30 wt.%). This approach also allows for independent tuning of the metal nanoparticle size (from 2 to 50 nm) and textural parameters, such as surface area (50–600 m2/g), average pore size (3–8 nm), and pore volume (0.05–0.6 cm3/g) of the materials during the one-step combustion. This new approach also enables uniform incorporation of metal nanoparticles within a porous silica matrix. This feature allows for synthesis of encapsulated stable ultra-small metallic nanoparticles with unusual properties. We tested Ni/SiO2 nanoscale materials with different textural parameters as catalysts in the ethanol decomposition reaction. The catalysts exhibited high activity toward hydrogen generation for ∼100 h. The relevant links between the textural parameters and stability of the catalysts are revealed. Characterization of the spent catalysts showed no structural changes, indicating superior stability over long periods of time. We also used spark plasma sintering (SPS) of Ni/SiO2 and Cu/SiO2 nanoscale materials to fabricate porous (70–80%) compact samples. These materials exhibited significantly low thermal diffusivity, which makes them attractive for thermal management applications. We also showed that the simple preparation method allows for production of large batches of final product, such as 10–50 g, in laboratory conditions.
      Graphical abstract image

      PubDate: 2017-09-02T10:45:50Z
      DOI: 10.1016/j.micromeso.2017.08.044
      Issue No: Vol. 257 (2017)
       
  • Synthesis of MCM-48 granules with bimodal pore systems via pseudomorphic
           transformation of porous glass
    • Authors: Hans Uhlig; Tom Muenster; Gert Kloess; Stefan G. Ebbinghaus; Wolf-Dietrich Einicke; Roger Gläser; Dirk Enke
      Pages: 185 - 192
      Abstract: Publication date: February 2018
      Source:Microporous and Mesoporous Materials, Volume 257
      Author(s): Hans Uhlig, Tom Muenster, Gert Kloess, Stefan G. Ebbinghaus, Wolf-Dietrich Einicke, Roger Gläser, Dirk Enke
      It was shown in previous publications that porous glasses can be transformed into MCM-41 materials with monomodal or bimodal (hierarchical) pore systems. In this study we describe the synthesis of MCM-48 granules with a bimodal pore structure via pseudomorphic transformation of porous glasses. Due to the cubic network of the MCM-48 structure, such materials are characterized by an improved mass transfer inside the pores compared to the 2 dimensional MCM-41 pore system. This represents an advantage for applications as catalyst support. Porous glass granules (100–200 μm particle size) with a pore diameter of 150 nm and a pore volume of 1.44 cm3/g were used as starting materials. The transformation process was controlled via different concentrations of cetyltrimethylammoniumhydroxide (CTAOH). The products were characterized by nitrogen adsorption, mercury intrusion, x-ray diffraction, scanning electron microscopy and light microscopy. The results confirmed the successful synthesis of MCM-48 particles with a hierarchical pore structure. The starting pore system with 150 nm diameter disintegrated during the transformation process because of the formation of MCM-48 clusters. A new pore system with approximately 3000 nm in diameter was formed among these clusters. A cavitation effect was observed during nitrogen adsorption/desorption measurements. This indicates that some parts of the starting pore system were entrapped by MCM-48 clusters. This can be explained with the higher concentration of the surfactant solution during transformation of the starting glass into the MCM-48 phase, which leads to a higher solubility and mobility of the silica source. Furthermore, the dependence of the quality of synthesized MCM-48 concerning geometry and structure of the starting materials was investigated by transformation of AEROSIL® 200. Due to the particulate and non-porous character of this starting material just a minor cavitation effect was observed during the physisorption measurements.
      Graphical abstract image

      PubDate: 2017-09-02T10:45:50Z
      DOI: 10.1016/j.micromeso.2017.08.033
      Issue No: Vol. 257 (2017)
       
 
 
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